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Protecting Our Water Environment

Metropolitan Water Reclamation District of Greater Chicago

IEPA ATTACHMENT NO.

BOARD OF

COMMISSIONERS

Terrence J. O'Brien

President

Kathleen Therese Meany

Wce President

Gloria Alto MaJewski

Chairman Of Finance

CHICAGO, ILLINOIS 60611-3154

312-751.5600

Harry "Bus* Yourell

John C. Farnan, P.E.

General Superintendent

Division of Water Pollution Control

Bureau of Water

Illinois Environmental Protection Agency

1021 North Grand Avenue East

P.O. Box 19276

Springfield, Illinois 62794-9278

Dear Mr. Frevert:

Subject: Evaluation of Management Alternatives for the Chicago

Area Waterways: (a) Investigation of Alternative

Technologies for Effluent Disinfection and (b) Estimation

of the Cost of Effluent Disinfection

The Metropolitan Water Reclamation District of Greater Chicago

submitted a report entitled "Technical Memorandum 1WQ:

Protection Agency on August 31, 2005.

The report included

conceptual level cost estimates for the design, construction,

operation,?

and maintenance of the recommended effluent

disinfection technology(ies), ozonation and ultraviolet

radiation (UV). Tables 1.26 and 1.27 summarize the opinion of

probable costs for UV and ozone disinfection, with and without

filtration. This letter addresses the changes that need to be

made to these tables since our submittal, dated August 31, 2005.

Change No. 1 will address the possibility of potential future

electrical rate changes. Change No. 2 will address a table

labeling correction and a missing line item.

The details of

these changes are presented below:

CHANGE NO. 1

1. Since the conceptual level cost estimates as presented in

the report were based on current electrical rates, the cost

estimates may change significantly should the electrical

C. Farnan

General Superintendent

Mr. Toby Frevert

? 2?

November 8, 2005

rates increase in the future. Therefore, Tables 1.26 and

1.27 (Pages 79 and 80, respectively) were revised, with an

additional footnote describing the possible cost impacts

based on electrical rates. Added footnote is as follows:

"* Total Annual O&M Cost is based on current electrical

rate at $0.075 per kilowatt-hour. This cost may change

significantly should the electrical rates increase in

the future."

CHANGE NO. 2

2a.

A line item was missing in Table 1.26. A new line item

"Total Annual O&M Cost" was inserted below "D. Disinfection

System". Note that this change does not affect the Total

Present Worth.

2b.

The line item "Total Present Worth O&M Cost" in Table 1.27

should have been "Total Annual O&M Cost". A new line item

"Total Present Worth O&M Cost" was inserted below the

revised "Total Annual O&M Cost". Note that these changes

do not affect the Total Present Worth.

Attached are the revised pages. Please replace Page 79 and 80 of

the report with the attached.

If you have any questions, please contact Mr. Richard Lanyon at

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8/26/05

TABLE 1.27

OPINION OF PROBABLE COSTS OF UV AND OZONE DISINFECTION FOR

NORTH SIDE WRP, STICKNEY WRP, AND CALUMET WRP

(WITHOUT FILTRATION)

NORTH SIDE WRP

STICKNEY WRP

CALUMET WRP

Capital Cost Estimates, in

B. Low Lift Pump Station

$ 54

$174

$59

C. Disinfection System

Operation and Maintenance Cost

Estimates, in millions

A. General Site Work

$ 0

B. Low Lift Pump Station

$ 1.1

$4.1

$1.7

C. Disinfection System

Total Annual O&M Cost*

Total Present Worth O&M Cost

Total Present Worth,

Annual Debt Services Cost, in

($14)

($30)

($42)

($9)

($15)

Total Annual O&M Cost is based on current electrical rate at $0.075 per kilowatt-hour. This cost may change significantly

should the electrical rates increase in the future.

** Based on interest rate of 5.5% for 20 years.

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SUMMARY OF OPINIONS OF PROBABLE COST

As discussed previously, disinfection cost opinions for North Side, Stickney, and Calumet WRP

were developed based on a low-lift pump station, a filtration facility, and a disinfection system.

Filtration was included for both disinfection alternatives because of the uncertain effects of TSS

on disinfection efficiency. Table 1.26 presents a summary table of the opinion of probable costs

for both UV and Ozone disinfection facilities for the three WRPs, including filtration.

TABLE 1.26

OPINION OF PROBABLE COSTS OF UV AND OZONE DISINFECTION FOR

NORTH SIDE

WRP, STICKNEY WRP, AND CALUMET WRP

(WITH FILTRATION)

NORTH SIDE WRP

STICKNEY WRP

CALUMET WRP

Capital Cost Estimates, in

B. Low Lift Pump Station

$ 54

$174

$59

C. Tertiary Filtration

$ 168

$642

$208

D. Disinfection System

Operation and Maintenance Cost

Estimates, in millions

A. General Site Work

$ 0

B. Low Lift Pump Station

C. Tertiary Filtration

$ 2.3

$4.2

$2.3

D. Disinfection System

Total Annual O&M Cost*

Total Present Worth O&M Cost

Total Present

Worth, in

millions

Annual Debt

21)

28)

($84)

($95)

($26)

($33)

* Total Annual O&M Cost is based on current electrical rate at $0.075 per kilowatt-hour. This cost may change significantly

should the electrical rates increase in the future.

** Based on interest rate of 5.5% for 20 years.

As shown from Table 126, filtration facilities contribute more than half of the probable

construction costs for all three WRPs. Since it is uncertain if filtration will be needed prior to

either one of the disinfection alternatives, Table 1.27 presents a summary of the opinion of

probable costs for both disinfection alternatives

without

filtration.

Metropolitan Water Reclamation District of Greater Chicago

BOARD OF COMMISSIONERS

Terrence J. O'Brien

President

Kathleen Therese Meany

Vice President

Gloria Alitto Ma}ewski

Chairman Of Finance

CHICAGO, ILLINOIS 60611-3154

Genera! Superintendent

312 •751 .

7900 FAX 312 •751-5681

August 31, 2005

Mr. Toby Frevert

Division of Water Pollution Control

Bureau of Water

Illinois Environmental Protection Agency

1021 North Grand Avenue East

P.O. Box 19276

Springfield, Illinois 62794-9278

Dear Mr. Frevert:

Subject: Evaluation of Management Alternatives for the Chicago

Area Waterways:

a. Investigation of Alternative Technologies for

Effluent Disinfection

Estimation of the Cost of Effluent Disinfection

The Metropolitan Water Reclamation District of Greater Chicago

(MWRDGC), at the request of the Illinois Environmental

Protection Agency (IEPA), hereby submits the enclosed reported

entitled "Technical Memorandum 1WQ: Disinfection Evaluation".

The MWRDGC foLmed a committee

of experts from

academia to

investigate possible effluent disinfection technologies and

recommend a technology or technologies appropriate for the

MWRDGC's Calumet, North Side and Stickney Water Reclamation

Plants (WRPs). Further, the MWRDGC had conceptual level cost

estimates prepared for the design, construction, operation and

maintenance of the selected effluent disinfection technologies.

Using the services of Consoer Townsend Envirodyne Engineers,

Inc. (CTE), this committee of experts reviewed and evaluated

effluent disinfection alternatives for the Calumet, North Side

and Stickney WRPs. Based upon the findings of these experts,

the MWRDGC selected ozone and ultraviolet radiation as the

General Superintendent

Mr. Toby Frevert?

-2-?

August 31, 2005

investigation and selection process was presented to a meeting

of the Chicago Area Waterways (CAWs) Use Attainability Analysis

(UAA) Study Stakeholders Advisory Committee (SAC) on June 22, 2005.

Subsequently, cost estimates for each selected disinfection

technology were prepared for each WRP by the three engineering

consulting firms developing master plans for these WRPs.

On October 18, 2005, another meeting of the UAA Study SAC is

scheduled and CTE will give a power point presentation

summarizing the cost estimating portion of the enclosed report.

The MWRDGC believes that this report will be useful in the

development of appropriate and cost-effective water quality

management strategies for the CAWs.

If you have any questions, please contact Mr. Richard Lanyon at

METROPOLITAN WATER RECLAMATION DISTRICT

OF GREATER CHICAGO

MASTER PLAN

NORTH SIDE WATER RECLAMATION PLANT

Submitted by:

CTE

AECOM

MWRDGC Project No. 04-014-2P

CTE Project No. 40779

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8/26/05

TABLE OF CONTENTS

LONG LIST OF DISINFECTION TECHNOLOGIES

Introduction?

Potential Disinfection Alternatives

Chlorination ?

Ozone ?

Ultraviolet Disinfection

Chlorination-Dechlorination

Chlorine Dioxide

Bromine Compounds

Emerging Wastewater Disinfection Technologies

EVALUATION OF LONG LIST OF DISINFECTION ALTERNATIVES

MEDIUM LIST OF ALTERNATIVES

SCORING OF QUALITATIVE ECONOMIC AND NON ECONOMIC

CRITERIA MATRIX

Desirable Performance Requirements

Qualitative Economic Requirements

Indirect Environmental Health Impacts

Public Perception Issues

SELECTION OF RECOMMENDED ALTERNATIVE(S)

OPINION OF PROBABLE COSTS FOR RECOMMENDED ALTERNATIVES

Introduction

Assumptions and Unit Costs

North Side WRP

Ultraviolet Disinfection

Ultraviolet Disinfection

- Background

Location on Site (Site Plan)

Site Specific Issues

Cost Summary

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Ultraviolet Disinfection

Site Specific Issues ?

Cost Summary

SUMMARY OF OPINIONS OF PROBABLE COST

APPENDIX

A Detailed Costs Breakdown for North Side, Stickney, and Calumet WRP

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LIST OF TABLES

Table 1.1 – Ozone

Table 1.2 – Ultraviolet (UV) Irradiation

Table 1.3 – Gas Chlorination/Sulfur Dioxide Gas Dechlorination

Table 1.4 – Liquid and Dry Chemical Chlorination/Liquid Dechlorination

Table 1.5 – Chlorine Dioxide

Table 1.6 – Bromine Compounds

Table 1.7 – Sequential Disinfection Processes

Table 1.8 – Membrane Processes

Table 1.9 – Summary of Disinfection Technologies Issues

Table 1.10 – Scoring of Qualitative Economic and Non-Economic Criteria Matrix.... 36-37

Table 1.11 – NSWRP – UV Disinfection System Sizing Data

Table 1.12 – NSWRP – Tertiary Filtration System Sizing Data

Table 1.13 – NSWRP – Opinion of Probable Costs for UV Disinfection Facilities

Table 1.14 – NSWRP – Ozone Disinfection System Sizing Data

Table 1.15 –NSWRP – Opinion of Probable Costs for Ozone Disinfection Facilities

Table 1.16 – SWRP – UV Disinfection System Sizing Data

Table 1.17 – SWRP – Tertiary Filtration System Sizing Data

Table 1.18 – SWRP – Opinion of Probable Costs for UV Disinfection Facilities

Table 1.19 – SWRP – Ozone Disinfection System Sizing Data

Table 1.20 – SWRP – Opinion of Probable Costs for Ozone Disinfection Facilities

Table 1.21 – Calumet WRP – UV Disinfection System Sizing Data

Table 1.22 – Calumet WRP – Tertiary Filtration System Sizing Data

Table 1.23 – Calumet WRP – Opinion of Probable Costs for UV Disinfection Facilities..73

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Table 1.24 — Calumet WRP — Ozone Disinfection System Sizing Data

Table 1.25 — Calumet WRP — Opinion of Probable Costs for Ozone

Disinfection Facilities

Table 1.26 — Opinion of Probable Costs of UV and Ozone Disinfection for

North Side WRP Stickney WRP, and Calumet WRP (with Filtration)

Table 1.27 — Opinion of Probable Costs of UV and Ozone Disinfection for

North Side WRP Stickney WRP, and Calumet WRP (without Filtration)

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LIST OF FIGURES

Figure 1.1 Chlorination Disinfection System

Figure 1.2 Ozone Disinfection Process Schematic

Figure 1.3 Ozone Disinfection System

Figure 1.4 Medium Pressure UV Disinfection Process

Figure 1.5 Chloride Dioxide Disinfection Process Schematic

Figure 1.6 Overall Site Plan For UV Disinfection North Side WRP

Figure 1.7 Partial Site Plan for UV Disinfection North Side WRP

Figure 1.8 Overall Site Plan for Ozone Disinfection North Side WRP

Figure 1.9 Partial Site Plan for Ozone Disinfection North Side WRP

Figure 1.10 Site Plan — UV Disinfection Stickney WRP

Figure 1.11 Partial Site Plan — UV Disinfection Stickney WRP

Figure 1.12 Site Plan — Ozone Disinfection Stickney WRP

Figure 1.13 Partial Site Plan — Ozone Disinfection Stickney WRP

Figure 1.14 Overall Site Plan for UV Disinfection Calumet WRP

Figure 1.15 Partial Site Plan for UV Disinfection Calumet WRP

Figure 1.16 Overall Site Plan for Ozone Disinfection Calumet WRP

Figure 1.17 Partial Site Plan for Ozone Disinfection Calumet WRP

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INTRODUCTION

Background

Consoer Townsend Envirodyne Engineers, Inc. (CTE) was retained in 2004 by the Metropolitan

Water Reclamation District of Greater Chicago (District) to provide engineering services to

prepare a comprehensive Infrastructure and Process Needs Feasibility Study (Feasibility Study)

for the North Side Water Reclamation Plant (WRP) and a Water Quality (WQ) Strategy for

affected Chicago Area Waterways.

The WQ strategy includes determining the potential technologies, costs and impacts associated

End of Pipe Treatment of Combined Sewer Overflow (CSOs)

•

Supplemental Aeration of Chicago Area Waterways

•

Flow Augmentation for the Upper North Shore Channel and Bubbly Creek

Scope of Study

This report documents the results of a CTE study of effluent disinfection alternatives for the

District's North Side, Calumet and Stickney WRPs.

CTE assembled a task force of national experts to review technologies for wastewater

disinfection and prepare a recommendation for the technologies most suitable for cost

estimating purposes at the District's three largest WRPs.

The task force of experts includes:

Dr. Charles Haas

Department of Civil, Architectural and Environmental Engineering

Drexel University

Philadelphia, PA

Dr. Benito Marinas

Dept of Civil and Environmental Engineering

University of Illinois

Urbana, IL

Dr. Kellogg Schwab

Johns Hopkins Bloomberg School of Public Health

Department of Environmental Health Sciences

Division of Environmental Health Engineering

Baltimore, MD

The task force reviewed different effluent disinfection technologies and their range of pathogen

destruction efficiency, disinfection byproducts and impacts upon aquatic life and human health.

Their investigation also included an examination of the environmental and human health

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impacts of the energy required to operate the facility and for the processing and production of

process chemicals.

Ultimately the task force recommended a disinfection technology(s) for possible implementation

at the North Side, Stickney and Calumet WRPs.

The scope of work for the disinfection study included the following subtasks:

Subtask?

Description

Description and Summary of Disinfection Technologies

Evaluation of Alternatives

Workshop on Recommended Disinfection Technologies

Prepare Final Technical Memorandum

This report contains the Final Technical Memorandum (TM-1WQ) document for the CTE study

of effluent disinfection for the MWRDGC.

Study Objective

•

Provide a final recommendation for one or more disinfection technologies which is the

best fit for the District's North Side, Stickney and Calumet WRPs.

•

Prepare capital and operation and maintenance (O&M) cost estimates for the

construction of the recommended technology or technologies for the North Side,

Stickney and Calumet WRPs. The cost estimates for the Stickney and Calumet WRPs

will be provided by Black & Veatch and Metcalf & Eddy, respectively. CTE will prepare

the cost estimate for the North Side WRP.

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LONG LIST OF DISINFECTION TECHNOLOGIES

Introduction

There are a number of effluent disinfection alternative technologies that should be considered

for potential implementation by the District at its major treatment plants. To properly evaluate

and select disinfection alternatives, two levels of review will be used. This section of the report

will describe the first level of review. Based upon this first review, a number of alternatives will

be eliminated and the remaining acceptable alternatives will be evaluated in a second, more

detailed level of review.

Potential Disinfection Alternatives

Based upon the experience of the Task Force, the scientific literature textbooks, and manuals of

practice, the following disinfection alternatives were selected for the long list evaluation.

Sodium Hypochlorite (commercial grade)

1.3?

Sodium Hypochlorite (on-site generation)

Ozone generated from air

2.2?

Ozone generated from oxygen

Ultraviolet (UV) Radiation

Chlorination-Dechlorination

4.1?

Calcium Hypochlorite + Sodium Bisulfite

4.2?

Calcium Hypochlorite + Sulfur Dioxide

4.3

Sodium Hypochlorite + Sodium Bisulfite

4.4

Sodium Hypochlorite + Sulfur Dioxide

4.5

Sodium Hypochlorite (on-site) + Sodium Bisulfite

4.6?

Sodium Hypochlorite (on-site) + Sulfur Dioxide

4.7?

Chlorine Gas + Sodium Bisulfite

4.8?

Chlorine Gas + Sulfur Dioxide

Chlorine Dioxide

Bromine Compounds

Sequential Disinfection Processes

Membrane Processes

Chlorination

Today chlorine (in its many forms) is the most widely used disinfectant at both water and

wastewater treatment plants in the U.S. Chlorine reacts rapidly with water and can inactivate a

range of pathogens present.

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The inactivation mechanism appears to be damage to nucleic acids in the cell. Chlorine reacts

rapidly with ammonia and certain organic compounds to form chloramines and chlorinated

organic compounds. The combined chloramines are lower in germicidal value compared to free

chlorine.

The use of chlorine disinfection of wastewater can result in several adverse environmental

impacts, due to total chlorine residual in the receiving water and the formation of toxic

chlorinated organic compounds.

Chlorine Gas

Elemental chlorine gas has a density greater than air at room temperature and pressure. When

compressed, chlorine gas condenses into a liquid with the release of heat and a reduction of

volume of approximately 450 fold. Hence, commercial shipments of chlorine gas are made in

pressurized tanks to reduce shipment volume. Chlorine gas is an extremely volatile and

hazardous chemical and proper safety precautions must be exercised during all phases of

chlorine shipment, storage and use.

Federal air pollution regulations require that wastewater treatment plants using chlorine gas

comply with strict requirements to prevent accidental release including stringent record keeping

and emergency response measures. These federal accidental release requirements have

caused many municipal wastewater treatment plants to abandon chlorine gas as a disinfectant.

Most have chosen to use liquid sodium hypochlorite which is exempt from the accidental

release requirements.

Hypochlorite (Sodium Hypochlorite and Calcium Hypochlorite)

Chlorine can also be added to wastewater effluents using hypochlorite as the disinfecting agent.

The active compounds are the same as gaseous chlorine. The mechanism for bacterial kill is

also the same. Adverse environmental impacts are the same as gaseous chlorine.

Sodium hypochlorite is available commercially in solution form in solution strengths up to 16%

by weight. Typically solution strength is 12 to 15%. It is not practical to provide higher solution

strength since chemical stability rapidly diminishes with strengths above 16%. At ambient

temperatures, the half-life of sodium hypochlorite solution varies between 60 to 170 days for

solutions of 18 and 3 percent respectively. Sodium hypochlorite solution can be generated by

continuous electrolysis of brine solutions. The basic principle is the use of a direct current

electrical field to affect the oxidation of chlorine ion with the reduction of water to gaseous

hydrogen. The electrolysis operation consumes large amounts of electrical energy usually

about 1.5 kilowatt-hours are required to produce one kilogram of chlorine.

Calcium hypochlorite, sometimes referred to as powdered bleach, is a dry material typically

consisting of 65% chlorine. Often called high test hypochlorite (HTH), 1 kg of calcium

hypochlorite is equivalent to 0.65 kg of elemental chlorine. This solid is a white, hydroscopic

material that emits a strong, chlorine odor.

Advantages and Disadvantages of Chlorination

Whatever the form of chlorine, chlorination systems are reliable and flexible and the equipment

is not complex. It is relatively easy to apply and control chlorine in wastewater treatment. Even

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when dechlorination required, it is normally the lowest cost disinfection alternative in most

cases.

Worker safety is a real issue with gaseous chlorine but the hypochlorites are relatively safe.

The chlorination process for wastewater produces excellent reduction for many, but not all

pathogen and can negatively impact aquatic life unless dechlorination is practiced. Even with

dechlorination, there is a potential for discharge of toxic organic compounds which could

negatively affect aquatic and human health.

Figure 1.1 shows a picture of a chlorination disinfection system.

Later in this report, there is a section on chlorination-dechlorination. This later section

summarizes (Table 1.3 and 1.4) the advantages and disadvantages of the chlorination process.

Ozone

Ozone (03)

is an unstable gas that is produced when oxygen molecules are disassociated into

atomic oxygen (0) and subsequently collide with an oxygen (0

molecule. For commercial

production of ozone, an electrical discharge in a gas containing oxygen (air or pure oxygen) is

used to create the atomic oxygen.

At ordinary temperatures, ozone is a blue colored gas which has a distinctive odor. The gas is

commonly detected by individuals in close proximity to electrical equipment that produce a

spark discharge.

Ozone is a very strong oxidizing agent and will react with many organic and inorganic

compounds in the wastewater. These reactions are typically called "ozone demand". This

demand is important because the reacted ozone is no longer available for disinfection.

Wastewaters which have significant concentrations of organics or inorganics may require very

high levels of ozone to achieve disinfection.

The inorganic compounds in wastewater that can react with ozone include sulfite, nitrite, ferrous

iron, manganese and ammonia. The organic compounds that react with ozone include aromatic

aliphatic compounds, humic acids and pesticides.

Ozone Process

Figure 1.2 shows a simplified process diagram for an ozone disinfection system. Transfer of

ozone into the wastewater is the first step in meeting the disinfection objective, since ozone

must be transferred from the gas to the liquid before effective disinfection can begin. Once

transferred, the residual ozone must make contact with the pathogens in order for disinfection to

occur. Figure 1.3 shows a picture of an Ozone disinfection system.

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Figure 1.1 - Chlorination Disinfection System

Chlorine Contact Tanks

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Figure 1.2 — Ozone disinfection process schematic

"'Air Treatment System

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Figure 1.3 - Ozone Disinfection System

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Contact time is usually about 10 to 15 minutes and ozone dosages of about 6.0 to 8.0 mg/I are

usually sufficient to achieve effluent target bacterial levels.

Ozone is generated from either commercially pure oxygen or ambient air.

The estimated power for pure oxygen ozone generation is 9.0 kilowatt hours per pound of ozone

produced. Ozone generated from air requires about 11.0 kilowatt hours per pound of ozone

produced. Additional power is required for the gas preparation and drying system (air feed) or

for the oxygen generation system.

No matter what the source of the feed gas, the quality of the feed is critically important. The

feed gas must be oil-free, particle-free and dry. To achieve this, the feed gas must be pretreated

to remove moisture, particles and oil (if present). For oxygen feed systems, it is usually

necessary to pretreat for particles only since oil and moisture are usually not present in

significant quantities.

Cooling is a major aspect of ozone generation since the electrical discharge produces

considerable heat. Cooling is accomplished with either water, oil or Freon. For water cooling,

about 1.0 gallon of water is required for every gram of ozone produced. Typically, potable

water in a closed loop system is used which is in turn cooled by plant non-potable water. The

closed loop system is often treated to obtain "boiler water" quality water.

Ozone destruction is used to remove excess ozone in the contact basin off-gases prior to

venting. Safety is a major issue for such ozone destruction equipment since explosive

conditions can occur. The primary methods for ozone destruction are thermal destruction and

catalyst destruction.

Advantages and Disadvantages of Ozone

Table 1.1 contains a summary of the advantages and disadvantages of ozone.

Ozone equipment is complex to maintain and operate. Process control is difficult compared to

chlorination since changes in ozone demand cannot be monitored on a real time basis.

Ozone disinfection does add dissolved oxygen to a wastewater effluent but this may not be an

advantage if the effluent is already high in dissolved oxygen. Ozone has been shown in certain

instances to produce toxic and/or carcinogenic compounds but little is known about these

compounds.

Ozone is an excellent viral disinfection agent but since current disinfection standards are based

upon bacterial measurements, this advantage may not be of significant regulatory benefit.

Ozone gas can be toxic to humans, plants and animals if inhaled in sufficient quantities. Care

must be taken in the handling of the gas to prevent accidental release.

Ozone disinfection is relatively expensive with the cost of the ozone generation system being

the main cost item. Operating costs are very high due to the power demand since ozone is a

power intensive process.

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TABLE 1.1

OZONE

ADVANTAGES

Adds dissolved oxygen

Excellent virus kills

Short contact time (5 to 15 minutes)

No residual control required

No significant regrowth

No chemical storage required

Reacts with endocrine disruptors (reduction to some degree)

No increase of truck traffic

DISADVANTAGES

High capital costs

Equipment is complex to operate and maintain

- Reduced

Cryptosporidium

inactivation at low effluent temperatures

Little is known about ozone disinfection-by-products (only 8% of ozone by-products have

been identified.)

Ozone can increase formation of biodegradable organic compounds such as aldehydes

and keto-acids or bromate (if bromine is present)

Ozone gas is toxic to humans, animals, and plants

Ozone systems must have IEPA air permit

- High electrical power costs

Least used wastewater disinfection method in U.S.

Corrosion resistant materials required

Ozone destruction unit required

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Ultraviolet Disinfection

Although chlorination has been the disinfection method of choice in the U.S. for over 100 years,

ultraviolet (UV) irradiation has become the next most common alternative for effluent

disinfection. The emergence of UV irradiation may be attributed to the drawbacks of

chlorination and improvements in UV equipment.

Due to the problems with chlorination, UV disinfection has increased in U.S. For example, only

50 wastewater plants used UV in 1986 but by 1990 over 500 plants used the process. In 1998,

more than 1,000 treatment plants in the U.S. used UV disinfection.

Ultraviolet irradiation is a physical disinfection process. UV irradiation achieves disinfection by

inducing photo-biochemical changes within pathogens. Approximately 85% of the germicidal

output from UV lamps have a wavelength of about 254nm. The visible blue light emitted by the

lamps has a wavelength of 400 nm but this wavelength has no germicidal power. It is believed

that the disinfection power of UV irradiation is caused by damage to nucleic acids in the cell.

Lamp output

Lamp UV output changes with time. In general, output falls off quickly after about 1,000 to

2,000 hours of operation followed by a gradual decline. Most municipalities replace their UV

lamps after 5,000 to 10,000 hours of operation.

Fouling

The ability to deliver radiation from the source to the target is critical to the performance of UV

systems. Accumulation of insoluble materials on the surface of the UV tubes limits the UV

radiation dose. Control of lamp fouling is usually accomplished using a combination of physical

and chemical methods. Physical methods include mechanical wipers or brushes – as integral

components of individual manufacturer's devices. Chemical cleaners include acids and

detergents. The solutions can be applied by either wiping individual lamps or physical

immersion in tanks containing the cleaners. Some manufacturers have in-situ cleaning systems

which do not require removal of the lamps from the effluent flow.

Current System Designs

Original systems offered by manufacturers in the 1980's consisted of enclosed chambers using

either a submerged lamp system or a non-contact system. The technology has now evolved

into a modular, submerged lamp system installed in an open channel which has significantly

improved maintenance and afforded better hydraulics. Lamps are usually either low intensity,

low pressure mercury systems or high intensity, medium pressure systems.

Low pressure mercury lamp systems are the most common bulb system used in wastewater

treatment plants. However, the output UV intensity is low. These systems require relatively

large numbers of lamps in a fairly dense bank spacing (2 to 5 inch spacing). But these lamps

are widely available at relatively low cost with an effective lamp life about 10,000 hours.

The UV output of high intensity, medium pressure lamps is 8 to 16 times greater than low-

pressure bulbs. Therefore, lamp spacing is significantly greater with the need for fewer lamps so

that capital costs are lower. However lamp life is shorter (less than 8,000 hours) and the

electrical energy requirements are higher.

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Figure 1.4 – High Intensity-Medium Pressure UV Disinfection Process

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Advantages and Disadvantages of UV Disinfection

Table 1.2 contains a summary of the advantages and disadvantages of UV.

The UV process is relatively simple. The hardware is simple and maintenance does not require

high skill levels. The hazards to the process are low and only relate to electrical shock hazards.

The major advantage is the absence of a residual in the wastewater and no known impact upon

aquatic or human health.

The process is difficult to monitor since there is no residual germicide concentration. Electrical

energy requirements are high. Fouling can be a significant problem. Also, high suspended

solids, color, turbidity and soluble organic matter in the water can react with or absorb the UV

and affect effluent quality. Some facilities have experienced difficulties in meeting target effluent

bacterial levels due to the periodic presence of UV blockers from industrial wastes. UV blockers

are water soluble compounds which absorb UV spectrum light. Design of systems to deal with

these discharges can be difficult without pilot plant studies.

Chlorination – Dechlorination

In a previous section, the various forms of chlorine used to disinfect wastewater effluents were

discussed. Chlorination results in a significant residual chlorine concentration usually 1 to 3

mg/l. Because the level of residual is toxic to some aquatic species, most state agencies

require the chlorine residual to be reduced to about 0.05 mg/I before effluent discharge.

Dechlorination is the chemical removal of most traces of residual chlorine remaining after

chlorination. This is typically accomplished with sulfur dioxide (S02-gas)

or sodium bisulfite

(NaHS03-liquid).

In addition to the equipment and facilities required for chlorination, dechlorination requires the

following equipment and facilities:

•

Storage tanks (Liquid or Gas)

•

Pumps and other equipment for dosing

•

Rapid mixing for effective dispersal in the liquid

•

Analyzers and controllers for dose control

The reaction of the dechlorination chemical is very rapid and no contact tank is required. The

contact time between the dosing point and the point of effluent discharge is usually sufficient.

Sulfur Dioxide

Sulfur dioxide is the most popular method for dechlorination. Sulfur dioxide is a colorless gas

with a characteristic biting odor. The gas is stored as a liquid in a pressurized container.

Sulfur dioxide is not flammable or explosive. In the presence of moisture, SO

is extremely

corrosive. It is therefore necessary to use corrosive resistant materials for storage and dosing

equipment.

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TABLE 1.2

ULTRAVIOLET (UV) IRRADIATION

ADVANTAGES

–

No significant by-product discharge to receiving stream

Relatively simple equipment

Second most widely used disinfection process

No chemical storage required: worker safety is excellent

Low potential for neighborhood impact

No significant increase in truck traffic

Can inactivate

Cryptosporidium, Giardia

Inactivation efficiency unaffected by temperature

DISADVANTAGES

High capital costs

High operating costs for electricity

No germicidal residual – operational control can be difficult

Does not react well to change in transmittance or flow

Fouling is a significant issue and causes maintenance and performance problems

Intermittent presence of UV blockers can cause permit violations

Certain viruses are poorly inactivated

- Need reliable power sources

Labor and cost intensive for lamp replacement and disposal

Possible permit issues (hazardous waste)

- No impact on endocrine disruptors

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The chemical reaction of SO

results in the conversion of the chlorine and chloramines ions to

chloride ions. A small amount of sulfuric and hydrochloric acid is formed from the reaction but

the pH of the wastewater is rarely affected. If some organics are present, an excess of sulfur

dioxide may be needed, but excess dosages are to be avoided because it may cause a

dissolved oxygen reduction and a drop in pH.

The chemical reaction of sulfur dioxide and chlorine is 1:1. That is, one mg/I of sulfur dioxide

will remove a chlorine residual of one mg/I.

Exposure Hazard to SO2

Sulfur dioxide is extremely hazardous and must be handled with caution. If you inhale sufficient

sulfur dioxide gas, it will cause significant damage to mucous membranes and the lungs.

Exposure to high levels of sulfur dioxide gas can cause death. The gas is heavier than air and

can concentrate in low areas.

Method of SO Control

Residual sulfur dioxide in plant effluent should be measured to ensure that over dosing does not

occur. A residual sulfur dioxide level of 0.5 mg/I is sufficient to reduce residual chlorine

concentrations to near zero.

Sulfur Dioxide Equipment

Sulfur dioxide containers and handling facilities are nearly the same as those for gaseous

chlorine. However, the materials should be carefully selected due to the aggressive corrosive

action of sulfur dioxide.

Municipal wastewater treatment facilities with sulfur dioxide storage facilities are subject to

stringent federal accidental release regulations. These regulations have caused many facilities

using sulfur dioxide to convert to the use of liquid sodium bisulfite.

Sodium Bisulfite

Sodium bisulfite is also used for dechlorination. Upon dissolution in water, this salt produces

sulfite (SO3)

ion which is the active dechlorinating agent. The salt is available as a dry powder

or liquid. However, municipal wastewater treatment plants typically utilize the liquid form of the

salt.

The sodium bisulfite salt is typically more expensive per pound of active dechlorination agent

than SO2

. But often the safety and handling of the liquid outweigh the cost in comparison to

sulfur dioxide.

Advantages/Disadvantages of Chlorination/Dechlorination

The choice of SO2

versus sodium bisulfite is dictated by similar considerations to those that

govern the selection of gaseous chlorine versus the hypochlorites. If sulfur dioxide is used, the

same types of issues (safety, accidental release) associated with gaseous chlorine apply.

Because of the safety and accidental release issues, it is often decided to use liquid sodium

bisulfite for dechlorination.

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Both SO2

and sodium bisulfite produce the same active agent, the sulfite ion. Thus both have

the same environmental impacts and decisions between these alternatives are based almost

solely upon safety, accidental release risk and cost. The storage and dosing of SO

is also

more complex to maintain and operate than sodium bisulfite equipment, therefore this may

influence the decision as well.

Table 1.3 and 1.4 contain summaries of the advantages and disadvantages of Gas

Chlorination/Gas Dechlorination (Table 1.3) and Liquid and Dry Chemical Chlorination/Liquid

Dechlorination (Table 1.4).

Chlorine Dioxide

Chlorine dioxide (CIO2)

has been used on a full-scale at drinking water plants. It is especially

useful for waters containing phenols or other taste and odor producing compounds. It is a

proven disinfectant equal to or greater than chlorine.

The environmental impacts of chlorine dioxide are not well established. There is a belief that it

produces lower amounts of toxic chlorinated organic compounds but further research is needed

to confirm this.

Production of Chlorine Dioxide

Chlorine dioxide is an extremely unstable and explosive gas. Therefore, it cannot be transported

and must be generated on-site.

The most commonly used on-site production process for chlorine dioxide is shown in Figure 5.

Gaseous chlorine is reacted with sodium chlorite to produce gaseous chlorine dioxide which is

then dissolved in water and applied to the wastewater.

Sodium chlorite is very combustible with organic compounds. Skin should not come in contact

with this chemical to avoid bums.

Chlorine dioxide has not received a great deal of attention as a wastewater disinfectant due to

the on-site generation requirement and the high chemical costs. The overall system is complex

to operate and maintain even compared to gaseous chlorination. Safety hazards include

handling two dangerous chemicals (gaseous chlorine and sodium chlorite). There is no known

full-scale use of this process at municipal wastewater treatment plants.

Advantages/Disadvantages of Chlorine Dioxide

Table 1.5 contains a summary of the advantages and disadvantages of chlorine dioxide.

Bromine Compounds

Bromine will form monobromamines and dibromamines when added to wastewater.

Bromamines have been found to be very effective as a disinfectant with shorter lived residuals

than chloramines. Because bromamines are stronger disinfectants than chloramines, shorter

contact times are needed compared to chlorine. Environmental impacts associated with

bromine are believed to be less adverse than those associated with chlorine since lower

amounts of bromine compounds are formed. However, more research is needed to determine

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TABLE 1.3

GAS

CHLORINATION/SULFUR DIOXIDE

GAS

DECHLORINATION

ADVANTAGES

—

Chlorination/Dechlorination is most widely used wastewater disinfection method

Operational control is excellent

—

Maintenance requirements are low

—

Very reliable systems

—

Reacts well to changes in effluent quality

—

Produces some viral inactivation if adequate contact time and dose are achieved

—

Chlorine gas is low cost form of chlorine

—

Sulfur dioxide gas is low cost dechlorination chemical

DISADVANTAGES

—

Gaseous chlorine and sulfur dioxide gas present regulatory and security issues

(accidental release)

—

Gaseous chlorine and sulfur dioxide gas present significant worker and neighbor safety

and other protozoa and no inactivation of

Cryptosporidium

—

Chlorine byproducts toxic to aquatic community and humans

—

Inactivation efficiency decreases with decreasing temperature and increasing pH

—

Combined chlorine, formed during occurrence of high ammonia nitrogen, is a weaker

disinfectant compared to free chlorine

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TABLE 1.4

LIQUID AND DRY CHEMICAL CHLORINATION/LIQUID DECHLORINATION

ADVANTAGES

–

Many plants have switched to liquid-dry chlorination/liquid dechlorination because of

accidental release regulations

–

Operational control is excellent

–

Maintenance requirements are low

–

Liquid and dry forms of chlorine and liquid dechlorination pose little hazard to workers

and neighbors

–

Very reliable systems

–

Reacts well to changes in effluent quality

–

Produces some viral inactivation if adequate contact time and dose are achieved

DISADVANTAGES

–

Significant liquid chemical storage required

–

Liquid/dry chlorination/liquid dechlorination is typically higher in cost than gas

chlorination/gas dechlorination

–

Dry chlorine form presents operational issues (dissolution in water)

– Low inactivation of

Giardia

and other protozoa and no inactivation of

Cryptosporidium

–

Chlorine byproducts toxic to aquatic community and humans

–

Inactivation efficiency decreases with decreasing temperature (below 10 – 12°C) and

increasing pH (above pH 7.6)

–

Combined chlorine, formed during occurrence of high ammonia nitrogen, is a weaker

disinfectant compared to free chlorine

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TABLE 1.5

CHLORINE DIOXIDE

ADVANTAGES

Higher oxidation potential than chlorine

Removes phenols and other organics better than chlorine

–

More effective viricide than chlorine

–

Does not react with ammonia

DISADVANTAGES

Complex on-site generation process

On-site generation requires gaseous chlorine use

No known full-scale use in wastewater plants

By-product formation is relatively unknown

Inactivation efficiency decreases with decreasing temperature

Has the same neighbor and worker safety disadvantages as gas chlorination

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Figure 1.5 – Chloride Dioxide Disinfection Process Schematic

SODIUM CHLORITE

SOLUTION TANK

NaCIO2

Source: U.S. Environmental Protection Agency, EPA – 600/8-78-018, October 1978.

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if these bromine compounds may be toxic at high concentrations. If bioaccumulation occurs,

these compounds could have toxic/carcinogenic effects.

The uses of bromine compounds (such as sodium bromide) have been studied at the research

and pilot level for wastewater disinfection. Brominated organics such as bromoform and

mixtures of chlorinated and brominated organics are formed when bromine compounds are

used as a disinfectant.

Advantages/Disadvantages of Bromine Compounds

Table 1.6 contains a summary of the advantages and disadvantages of bromine compounds.

There is no full-scale experience with the use of bromide compounds for wastewater

disinfection. Mr. G.C. White in his latest (1999) edition of the "Handbook of Chlorination and

Alternative Disinfectants" states: "there is insufficient field experience for proper evaluation."

Emerging Wastewater Disinfection Technologies

The disinfection technologies evaluated in the preceding sections were selected based on

current regulatory requirements for wastewater effluent discharge regarding indicator

organisms. However, more advanced technologies might be required in the event that specific

pathogens become regulated in the future. Although this is not of concern now, a brief review of

emerging sequential disinfection and membrane technologies that could be used in the future

for the control of emerging pathogens in wastewater are presented in this section for the

purpose of completeness.

Sequential Disinfection Processes

Although many specific viral, bacterial, and protozoan pathogens would be controlled

adequately with the technologies described in previous sections, they will not be generally

effective for controlling all potentially emerging pathogens. For example, UV disinfection might

be the only technology capable of inactivating protozoan cysts in wastewater effluents. Chlorine

is practically ineffective to control

Cryptosporidium parvum

cysts, and achieving the required

control in the case of ozone and chlorine dioxide might be generally difficult and unreliable due

to the occurrence of a relatively high disinfectant demand. In contrast, specific enteric viruses

such as adenoviruses have relatively high resistance to inactivation by UV light, but they are

controlled adequately with chemical disinfectants with the exception of combined chlorine.

Consequently, controlling all pathogens of interest might require the use of sequential

disinfection processes.

The use of sequential disinfection processes such as UV light followed by free chlorine, and

ozone followed by free or combined chlorine might provide adequate protection against a wide

range of viral, bacterial and protozoan pathogens. Such sequential disinfection approaches

might be the focus of greater attention if specific pathogens become the target of future

regulatory efforts. However, these concepts have not operated tested or operated on a full-

scale.

Table 1.7 contains a summary of advantages and disadvantages of sequential disinfection

processes.

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TABLE 1.6

BROMINE COMPOUNDS

ADVANTAGES

Shorter contact times compared to chlorine

Because of shorter lived residuals than chlorine by-products, should have lower toxicity

than chlorine

Physical equipment similar to chlorination

Maintenance and operation issues similar to chlorination

DISADVANTAGES

Environmental effects of by-products is relatively unknown (bromine not acceptable for

drinking water treatment)

No full-scale experience in wastewater plants

Expensive chemical

Usually used in conjunction with chlorine to reduce cost

Inactivation efficiency decreases with decreasing temperature

Careful handling is required by workers

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TABLE 1.7

SEQUENTIAL DISINFECTION PROCESSES

ADVANTAGES

Can control wide range of pathogens:

DISADVANTAGES

Current disinfection targets are bacteria only

Not tested on full-scale

No full-scale operating experience

Increased complexity, maintenance, and possibly costs due to multiple processes

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Membrane Processes

Membranes are currently being used in wastewater treatment applications for the tertiary

removal of dissolved salts, organic compounds, phosphorus, colloidal and suspended solids,

and pathogens. Membrane technologies for wastewater treatment include the use of membrane

bioreactors as a replacement for secondary clarifiers, low-pressure membranes to provide a

higher degree of solids removal following secondary clarification, or high-pressure membranes

for treatment and production of high-quality product water suitable for indirect potable reuse and

high-purity industrial process water.

The biggest single technical challenge with the use of membranes for wastewater treatment is

the high level of unavoidable fouling. Membrane fouling is mainly due to colloids, dissolved

organic material, and bacteria that are present in secondary effluent with resultant decreases in

product water flux at constant feed pressure (or increases in feed pressure at constant product

water flux) and frequency of membrane cleaning, dramatically reducing membrane operational

life . The nature of this fouling is poorly understood and stands as a key impediment to

developing improved methods for membrane cleaning. Other technical barriers include the

difficulty and expense of managing the concentrate from high pressure membranes, and the

undefined ability of low pressure membranes to effectively remove all chemical contaminants

and pathogens of concern that are found in municipal secondary effluent. Although substantial

current research is directed toward producing the ideal membrane system, little effort has been

made for standardization, which is needed to increase interchangeability among membranes

and membrane systems produced by different manufacturers. Sensitivity analyses on design

and operating parameters for membrane systems suggests that costs are also quite sensitive to

product water flux. Accurate estimates of flux are necessary to compare membrane application

cost with the cost of other technologies. Presently, site-specific fluxes can only be obtained

through pilot studies.

Treating wastewater with membranes is a viable option when considering urban, agricultural, or

industrial reuse, groundwater recharge, salinity removal, or to meet very low effluent water

quality limits for nutrients. However, there has been no full-scale use of the technology as a

method for effluent disinfection.

Table 1.8 contains a listing of the advantages and disadvantages of membrane process.

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TABLE 1.8

MEMBRANE PROCESSES

ADVANTAGES

–

Removes pathogens, salts organics, phosphorus, suspended and colloidal matter

DISADVANTAGES

–

Typically used for industrial waste and reclaimed water treatment

–

Fouling may be significant and is a poorly understood phenomena

–

Membranes are expensive

–

Management of concentrate is an issue

–

No full-scale experience for wastewater disinfection

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EVALUATION OF LONG LIST DISINFECTION ALTERNATIVES

An evaluation of the long list of disinfection alternatives was conducted with the objective of

constructing a medium list of alternatives for a further detailed evaluation. The task force and

the District reviewed the long list and eliminated those alternatives which would have no

practical application to the District's major WRPs.

In an effort to summarize the relevant issues associated with the various long list technologies

and assist in the evaluation of the long list alternatives, Table 1.9 was constructed.

The North Side and Calumet Plants rank among the largest WRPs in the U.S. while the

Stickney WRP is the largest in North America. Thus, because of a lack of large-scale

wastewater treatment plant effluent disinfection experience, the task force eliminated the

following long list technologies from further consideration:

Chlorine Dioxide

Bromine Compounds

Sequential Disinfection Processes

Membrane Processes

Because of District concerns with the potential hazards to humans and the environment due to

accidents or terrorism, either at the plant or during transportation, gas chlorination/gas

dechlorination options were also eliminated from the long list. Because the task force believes

that chlorination alone will not meet forecasted future water quality standards for chlorine

residual, chlorination alone was also eliminated from the long list.

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TABLE 1.9 – SUMMARY OF DISINFECTION TECHNOLOGY ISSUES

Technology

Pathogen Destruction

Efficiency

Byproducts and

impact on aquatic life

and human health and

safety

Energy required

to operate the

facility

Energy required for

processing and

production of chemicals

Relative Impacts of

Energy Production on

the Environment

Chlorination

Reacts rapidly with water

Can result in adverse

Energy required

On-site generation

Medium impact

and can inactivate many

environmental impacts

for chlorination at

requires 1.5 kwh per kg of

pathogens. Will kill some

due to formation of toxic

the treatment

chlorine. Off-site

viruses depending upon

chlorinated organic

plant is low if

commercial chlorine

operating conditions.

chemicals. As a gas, it is

extremely volatile and

similar energy demands.

Ozone

Will kill many pathogens.

Little information known

High demand for

Ozone is generated on-

Medium impact

Produces excellent virus

kills.

about byproducts.

Ozone gas is toxic to

Kills pathogens by damage

No known significant

Electrical energy

UV light is produced on-

High impact

to nucleic acids. Can

inactivate some parasites.

byproducts. UV

disinfection is relatively

Comments same as above

Same as chlorination.

Somewhat higher

Commercially available

dechlorination chemicals

require high electrical

energy for production.

Chlorine

More effective viricide than

Byproduct formation is

Generated on-

Commercial chlorine gas

High impact

Dioxide

chlorine.

relatively unknown. An

unstable and potentially

disinfectant and requires

less contact time than

chlorine.

relatively unknown.

Similar safety issues as

Potential approach to

Byproduct toxicity and

Depends upon

Depends upon processes

Depends upon

Disinfection

achieving a wide range of

safety issues depend

processes being

being used.

processes being used.

Could be used for removal

No byproducts formed.

of most human pathogens.

No significant safety

issues.

at the plant is

high.

does not require large

electrical energy.

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MEDIUM LIST OF ALTERNATIVES

Based upon the evaluation of the long list by the task force, the following technologies constitute

Generated from oxygen

Ultraviolet Disinfection

- Low Intensity

- High Intensity

Calcium hypochlorite plus sodium bisulfite

Sodium hypochlorite plus sodium bisulfite

Sodium hypochlorite (on-site) plus sodium bisulfite

These alternatives were evaluated using a matrix with the following criteria and weights:

Criteria

Weight

Group Total

Weight

Item Total

1.?

Desirable Performance Requirements

1.1. Safety

1.1.1. Low Risk to Operators from Accidental Releases and Waste

Products

1.1.2. Low Hazard Potential to Neighbors

1.1.3. Low Level of Onsite Chemical Storage

1.1.4. Low Potential for Malicious Adverse Occurrences

1.1.5. Low Hazard Potential for Transportation Spills and Releases

1.2.?

Operational Flexibility

1.2.1. Can Be Readily Adjusted for Variation in Flow

1.2.2. Can Be Readily Adjusted for Variation in Quality (Upstream

Operational Upsets)

1.2.3. Demand Easily Measured

1.3. Operational Reliability

1.3.1. Predictability of Performance

1.3.2. Reliability of Operations (Low Down Time)

1.4. Byproducts (DBP's)

1.4.1. Low Potential for Byproduct Formation

1.4.2. Low Ecotoxicity of Byproducts

1.4.3 Low Human Toxicity

1.5. Modification for Future Concerns

1.5.1. Can Be Adjusted to Achieve High Level Pathogen Reduction

1.5.2. Compatible with Possible Further Needs for Byproduct

Minimization

2.?

Qualitative Economic Requirements

2.1. Existence of Multiple Vendors for Equipment

2.2. Can Be Operated by Operators with Normal Training Levels

2.3. Low Sensitivity to Cost of Electricity

3. Indirect Environmental and Health Impacts

3.1 Environmental and Human Health Impacts of Energy Required to

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Operate the Facility

3.2 Environmental and Human Health Impacts of the Energy Required for

Processing and Production of Process Chemicals (Including

Byproducts)

3.3 Indirect Environmental and Health Impact of the Conversion and

Degradation of Process Chemicals

4.?

Public Perception Issues

4.1. Low Negative Perception by Environmental Organizations and Public

OVERALL TOTAL

100

Each alternative was scored for each of the above criteria according to the following scale:

Good – 3

Average – 2

Poor – 1

Each alternative was then evaluated relative to the weighting factor for each criteria. For each

alternative, the score for each alternative is multiplied by the criteria's weight to arrive at a total

score for that criteria. For example if an alternative receives a score of 3 for a criteria with a

weight of 10, the total score for that criteria is 3x10 = 30.

The evaluation criteria were a consensus decision of the District and the task force. It should be

noted that the evaluation criteria do not include estimated capital nor estimated operation and

maintenance costs. It was a consensus decision by the task force and the District that the

alternatives should be evaluated using qualitative economic and non-economic criteria without

regard to the numerical costs associated with the alternatives.

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SCORING OF QUALITATIVE ECONOMIC AND NON-ECONOMIC CRITERIA MATRIX

The criteria and weights discussed above were placed into a spreadsheet and scores were

assigned by the task force.

Below is an explanation of the scoring shown in Table 1.10.

1.?

Desirable Performance Requirements

1.1 Safety

1.1.1 - Low Risk to Operators From Accidental Releases and Waste Products

Liquid chlorine reacts with aluminum, tin, mercury, arsenic and gold at ordinary

temperatures. Hence chlorine in the liquid form can have an adverse effect on its

surroundings. Technologies involving the solid and on-site generated liquid forms of

chlorine with sulfite dechlorination were assigned the score of 2 because although they

present a lesser hazard than the gaseous form of chlorine there are still safety concerns

associated with these highly concentrated strong oxidizing agents, such as metal

corrosion and the associated risk of spills. Purchased liquid hypochlorite was assigned

a score of 1 since there is an increased chance of spills due to the transportation of this

chemical. Ozone was also assigned the intermediate score of 2 because although it is a

gas, it is produced in relatively low concentrations (less than 10 percent by weight) which

probably would not present a high hazard to workers. Finally, UV based technologies

are assigned a score of 2 in the case of low-intensity UV and the highest score of 3 in

the case of high-intensity UV. A higher score of 3 was assigned to the high-intensity

technology because the risk of releasing mercury is minimized by having to handle a

much lesser number of lamps as well as working with more secure and smaller reactors.

1.1.2 – Low Hazard Potential to Neighbors

The scores assigned to the various candidate technologies based on this criteria were

similar to those in section 1.1.1 except that the scores for UV low-intensity and dry

calcium hypochlorite were increased to 3 because UV is produced on site and thus does

not require transport through neighbor areas while the dangers from transport of the dry

form of chlorine is minimal.

1.1.3 - Low Level of Onsite Chemical Storage

Dry and wet forms of purchased chlorine would require a similarly significant greater

level of chemical storage capacity compared to on-site generation of chlorine or ozone,

or UV. Accordingly, the score of 1 was assigned to these candidate technologies. On-

site generation of chlorine would require some storage of chemicals from which chlorine

is generated and thus was assigned a score of 2. Ozone and UV technologies, not

requiring chemical storage, were assigned the maximum score of 3.

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TABLE 1.10 - SCORING OF QUALITATIVE ECONOMIC AND NON-ECONOMIC CRITERIA MATRIX

Group

Total

Item

Total

Ozone-

Air

Ozone -

Oxygen

UV-Low

Intensity-

Low

Pressure

UV-High

Intensity

-Medium

Pressure

CaOCI

Sodium

Bisulfite

NaOCI

Sodium

Bisulfite

Onsite

Generation

Sodium

Bisulfite

1.?

Desirable performance requirements

1.1.?Safety

1.1.1. Low risk to operators from accidental releases

and waste products

3222321

1.1.2.?

Low hazard potential to neighbors

1.1.3.?

Low level of onsite chemical storage

1.1.4. Low potential for malicious adverse

occurrences

3323222

1.1.5. Low hazard potential for transportation spills

and releases

333221

1.2.?

Operational flexibility

1.2.1. Can readily be adjusted for variation in flow

1.2.2. Can readily be adjusted for variation in quality

(upstream operational upsets)

221133

1.2.3. "demand" easily measured

223333

1.3.?Operational Reliability

1.3.1. Predictability of performance

1.3.2.?

Reliability of operations (low down time)

23223

1.4.?Byproducts (DBP's)

1.4.1. Low potential for byproduct formation

1.4.2. Low ecotoxicity of byproducts

1.4.3 Low human toxicity

3?1?1?

1.5.

Modification for future concerns

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Group

Total

Item

Total

Ozone-

Air

Ozone -

Oxygen

UV-Low

Intensity-

Low

Pressure

UV-High

Intensity

-Medium

Pressure

Ca0C1+

Sodium

Bisulfite

NaOCI

Sodium

Bisulfite

Onsite

Generation

Sodium

Bisulfite

1.5.1..

Can be adjusted to achieve high level pathogen

reduction

333231

1.5.2. Compatible with possible further needs for

byproduct minimization

Qualitative economic requirements

2.1. Existence of multiple vendors for equipment

322331

2.2. Can be operated by operators with normal

training levels

5222233

2.3.?

Low sensitivity to cost of electricity

Indirect Environmental and Health Impacts

3.1 Environmental and human health impacts of

energy required to operate the facility

5221

3.2 Environmental and human health impacts of the

energy required for processing and production of

process chemicals (including byproducts)

4331

3.3 Indirect environmental and health impact of the

conversion and degradation of process chemicals

4.?

Public Perception issues

4.1. Low negative perception by environmental

organizations and public

Economic Impacts

5.1 Low Estimated Capital Cost

5.2 Low Estimated Annual O&M Costs

OVERALL TOTAL

100

216

213

221

224

204

205

180

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1.1.4 - Low Potential for Malicious Adverse Occurrence

All options were given a score of either 2 or 3 because none of the technologies offer

significant opportunities for malicious occurrences. Ozone using high purity oxygen was

given a lower score then ozone using air since oxygen offers an opportunity for creating

an explosive condition. Since storage of the liquid and dry forms of purchased chlorine

is necessary, purchased chlorine was given a lower score than chlorine generated on-

site. High-intensity UV was given a lower score than low-intensity UV since the smaller

number of lamps may be more readily secured from those wishing to misuse them.

1.1.5 - Low Hazard Potential for Transportation Spills and Releases

The higher risk associated with the transport of chlorine liquids and solids was the basis

for assigning a score of 1 to these alternatives. On-site generated chlorine was given a

higher score of 2 since the chlorine produced is not transported. Ozone was considered

less hazardous than UV since ozone release would be less hazardous then mercury

release from broken bulbs. Ozone was given a score of 3 and UV was given a score of

1.2 Operational Flexibility

1.2.1 - Can Be Readily Adiusted for Variation in Flow.

UV cannot be readily adjusted for flow and was given a score of 1. UV lamps are either

on or off so it is usual practice to design a UV system in modules which can be added or

take in out of service when flow variations occur.

When flow variations occur in ozone systems, it is necessary to adjust the ozone output

both in terms of gas concentrations and gas flow rate. Operation and control of ozone

dosing systems is much more difficult compared to chlorine systems. Ozone was

assigned a score of 2, while purchased chlorine was assigned a score of 3. On-site

liquid chlorine systems were assigned a score of 2 because of the need to adjust

chlorine production to flow.

1.2.2 - Can Be Readily Adiusted for Variations in Quality.

UV lamp systems are either on or off and it is necessary to take modules off or on-line to

adjust for changes in effluent quality. UV was given a score of 1.

Ozone systems are less difficult to control than UV systems since ozone exit gas

concentrations can be used as a control variable. Purchased liquid and dry forms of

chlorine can be easily adjusted for changes to quality and were given a. score of 3. On-

site generated liquid chlorine requires adjustment of chlorine production to match

changes in effluent quality and was given a score of 2.

1.2.3 - Demand Easily Measured

All alternatives were given a score of 3 except for ozone. Ozone was given a score of 2

since equipment to measure ozone residuals in solution, particularly in the wastewater

matrix, is less developed than for chlorine UV.

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1.3 Operational Reliability

1.3.1 – Predictability of Performance

All options offer predictable performance if operated properly. But no option is better or

worse than another. A score of 2 was assigned to all options.

1.3.2 - Reliability of Operations

All options were given a score of 2 except for UV low intensity and purchased

hypochlorite. UV low intensity bulbs have been known to deteriorate rapidly with time

while hypochlorite solutions decrease in strength during storage.

1.4 Byproducts (DBPs)

1.4.1 - Low potential for Byproduct Formation

Chlorination produces the most known toxic disinfection byproducts thus all chlorination

processes were given a score of 1.

UV adds no significant toxic byproducts to effluents so it was given a score of 3.

Ozone has the potential to produce byproducts but it is believed that these are

potentially less toxic than chlorine byproducts. Ozone was given a score of 2.

1.4.2 - Low Ecotoxicity of Byproducts

The scoring for this criteria was the same as for criteria 1.4.1 because ecotoxicity is

directly related to the amounts and types of byproducts formed by the disinfection

alternatives.

1.4.3 - Low Human Toxicity

Research studies show that chlorination produces known human toxic compounds.

Thus chlorination alternatives are given the lowest score.

Scores for UV were the highest since this alternative does not produce toxic byproducts.

Ozone has reduced human toxic byproduct formation compared to chlorine but the

byproducts levels are not zero. Thus ozone was given a score of 2.

1.5 Modification for Future Concerns

1.5.1 - Can Be Adjusted to Achieve High Level Pathogen Reduction

None of the technologies can achieve reduction in all the potential pathogens present in

sewage. There are simply too many pathogens in sewage that are resistant to certain

disinfection alternatives and no single technology can reduce all pathogens to low levels.

Both ozone and high intensity UV treatment provide disinfection for a relatively wider

range of pathogens compared to all the chlorination options. Thus, high intensity UV and

ozone were given a score of 3 while all chlorination options were given a score of 1. UV

low intensity was given an intermediate score of 2.

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1.5.2 - Compatible with Possible Further Needs for Byproduct Minimization

All the chlorination options produce more known toxic amounts of byproducts than ozone

or UV. Thus all chlorination options were given a score of 1. UV forms no significant

byproducts while ozone does. Thus UV was given a score of 3 while ozone was given a

score of 2.

Qualitative Economic Requirements

2.1 - Existence of Multiple Equipment Vendors

Although multiple equipment vendors are available for all technologies evaluated (scores of 2 or

3), the highest score of 3 was given to technologies more commonly in use in municipal

wastewater treatment plants of similar capacities. Purchased forms of chlorine and low-intensity

UV were given a score of 3 since these are the most commonly used effluent disinfection

technologies.

2.2 – Can Be Operated by Operators with Normal Training Levels

Because of the relative simplicity and degree of automation of chlorine-based technologies, they

were all assigned the highest score of 3 in this category.

In contrast, because ozone and UV technologies require somewhat more complex operation

skills, these technologies were assigned an intermediate score of 2.

2.3 - Low Sensitivity to Cost of Electricity

Except for on-site generation, chlorine based technologies require the lowest level of energy

and thus were assigned the highest score of 3. Chlorine based technology with on-site

generation and ozone have intermediate energy requirements and thus were assigned the

intermediate score of 2. UV requires the highest level of energy and thus this process was

assigned the lowest score of 1 in this category.

Indirect Environmental and Health Impacts

3.1 – Environmental and Human Health Impacts of Energy Required to Operate the Facility

Actual energy requirements for each proposed disinfectant are complex and difficult to directly

compare. Based on the fact that wastewater plants usually purchase chlorine compounds used

for disinfection from outside vendors, the energy consumption for production of these

disinfectants is not part of the plant energy balance but energy used during production, handling

and shipping can be substantial. However, during wastewater treatment, energy uses for

chlorine based technologies produced off-site, require the lowest energy requirements and were

assigned the highest score of 3. On-site generation of chlorine requires additional energy and

thus was assigned a score of 2. UV processes were the most energy intensive and were

assigned the lowest score of 1. Ozone has a lower energy requirement than UV and was given

a score of 2.

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3.2 – Environmental and Human Health Impacts of the Energy Required for Processing and

Production of Chemicals (Including Byproducts)

The use of chlorine based treatment requires substantial chemical use with resulting high

production and transportation costs. The chlorine processes that use chemicals that are

transported to the facility, were all given the lowest score of 1. On-site generation of chlorine

reduced the energy for shipping and thus was given a score of 2. Ozonation does not require

the use of commercial chemicals and was given the highest score of 3. The production of high

intensity UV bulbs requires less energy then that for low intensity bulb production. Thus UV

high intensity was given a score of 2 and low intensity was given score of 1.

3.3 – Indirect Environmental Health Impacts of the Conversion and Degradation of Process

Chemicals

Chlorine based disinfection systems all produce the highest level of known toxic byproducts and

were given a score of 1. Ozone produces some known toxic byproducts but less than chlorine

and was given a score of 2. UV produces no significant byproducts but high-intensity UV has

the potential to produce potential changes in the constituents in wastewater while low-intensity

UV does not. Thus high-intensity UV was given a score of 2 while low-intensity UV was given a

score of 3.

4.?

Public Perception Issues

4.1 - Low Negative Perception by Environmental Organization and the Public

The use of chlorine based treatment requires substantial chemical use with resulting

transportation and safety concerns. Chlorination processes that use chemicals that are

transported to the facility were all given the score of 2. On-site generation of chlorine increased

the potential for neighbor negative reaction and thus was given a score of 1. Ozone and UV do

not require the use of chemicals but ozone has the potential for a toxic gas release and was

give a score of 2. High-intensity UV has a smaller footprint than low-intensity UV and was given

a score of 3 while low-intensity UV was given a score of 3.

As can be seen in Table 1.10, the UV-High Intensity disinfection alternative received the highest

scores.

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SELECTION OF RECOMMENDED ALTERNATIVE(S)

After a careful consideration of matrix scores, it was a consensus decision on the part of the

task force and the District that both UV (High Intensity-Medium Pressure) and Ozone (Oxygen)

disinfection alternatives will be carried forward by the three master plan consultants for

detailed cost estimation.

Although scores for both UV (High Intensity-Medium Pressure) and UV (Low Intensity-Low

Pressure) alternatives are close, the decision was made to consider UV (High Intensity-

Medium Pressure) only for detailed cost estimation. This is due to the concern of handling the

large numbers of low intensity UV lamps as compared to the numbers of high intensity UV

lamps. Similarly, although scores for Ozone (Air) is slightly higher than Ozone (Oxygen), the

capital and O&M costs for Ozone (Air) systems are approximately three to four times higher

than the Ozone (Oxygen) systems. Therefore, the decision was made to consider Ozone

(Oxygen) only for detailed cost estimation. Additionally, it is believed that there is no full-scale

Ozone (Air) system operating at a size similar to those being considered by the District.

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OPINION OF PROBABLE COSTS FOR RECOMMENDED ALTERNATIVES

In order to evaluate the impacts associated with disinfection at the North Side, Stickney, and

Calumet WRP's, this section presents assumptions, unit costs, and cost opinions for the three

WRPs. The District asked each of the engineering firms who are currently developing master

plans for these plants to prepare cost opinions for UV (High Intensity-Medium Pressure) and

Ozone (Oxygen). Below is a list of these firms and the WRP master plans which they are

currently developing.

Black & Veatch/Greeley and Hansen

Stickney

Metcalf & Eddy?

Calumet

Introduction

In addition to the technical evaluation of disinfection technology alternatives discussed

previously, the costs of constructing and operating the facilities required for disinfection is

another important factor in selecting a disinfection alternative. To provide an economic basis

of comparison for the two short-listed altematives, opinions of cost were developed based on a

standard set of design criteria among the North Side, Stickney, and Calumet WRP. This

section discusses how the cost opinions were developed for the three WRPs. Each WRP will

be discussed separately, considering both disinfection alternatives and the associated

disinfection-related issues at each plant. Note that cost opinions and the associated section

for each WRP were completed by the corresponding engineering firm. A cost summary table

for all three WRPs is presented at the end of this Technical Memorandum (TM). Detailed

costs breakdown are included in Appendix A.

Assumptions and Unit Costs

Two disinfection technologies, oxygen-generated ozonation and high intensity-medium

pressure UV irradiation, were selected to assess the cost impacts for implementation. Details

of technology descriptions and evaluation were discussed in previous sections.

In an effort to generate consistent cost opinions among the three WRPs, the District and the

engineering firms conducted a series of meetings to establish a common set of assumptions to

govern development of the costs at each plant. These meetings also established unit costs for

specific items that would be incorporated into all three cost opinions. The list below

summarizes the assumptions made and unit costs used to develop the cost opinions:

•

Design Criteria:

Design Flow: Maximum design flow was used. The specific flow rate chosen

for each plant will be discussed separately.

Proposed Effective Disinfection Limit (E. Coll, cfu/100 ml):

■

1,030 monthly geo-mean for North Side and Calumet

■

2,740 monthly geo-mean for Stickney

These disinfection limits assume that the proposed Use Attainability Analysis

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(UAA) bacteria water quality standards for the receiving streams will be

achieved at end-of-pipe at each WRP.

UV Disinfection:

UV Transmission: 65% minimum per IEPA standard

Ozone Disinfection:

o Ozone dosage: 8 mg/I

Ozone contact time: 10 minutes

•

The cost for a low-lift pump station and filtration facility was included in both

disinfection alternatives as separate items. Filtration design criteria shall follow the

Illinois Recommended Standards for Sewage Works (IRSSW) design standard with

filtration flow rates not to exceed 5 gallons per minute per square-foot (gpm/sf) with

one unit out of service under peak hourly condition.

•

Each plant will disinfect effluent from March through November. However, operation

for the low-lift pump stations and filtration facilities was assumed to be all year round.

•

Filters will be enclosed in a Filter Building.

•

Cost opinions were divided into the following categories:

o Site Work

Low Lift Pump Station

Filtration

o Ozone/UV facilities

•

Costs for major equipment at each plant (filters and ancillary filter equipment, oxygen

generation equipment, ozone generation equipment, UV equipment) were obtained

from one vendor for all three plants:

Technology/Process

Vendor

UV Irradiation?

Trojan Technologies, Inc.

Ozonation

Fuji Electric Systems Co., Ltd.

On-site Oxygen Generation

Praxair Inc.

Filtration?

US Filter (Zimpro Products)

•

An all inclusive capital unit cost of $60,000 per MGD was used for the low lift pump

station.

•

A cost of $200 per square foot was used for buildings other than the low lift pump

station. This unit cost includes slab on grade, architectural, mechanical, and building

electrical equipment. Major substructures such as tanks below grade were estimated

separately.

•

UV channels were enclosed in a UV building.

•

Poured-in-place concrete costs were as follows:

o Base slabs - $400 per cubic yard

o Walls - $650 per cubic yard

Elevated slabs - $700 per cubic yard

•

A present worth factor of 19.42 was used for all present worth calculations, based on a

3% interest rate for 20 years with a 3% inflation factor.

•

A power cost of $0.075/kW-hr was used for all three WRPs for consistency.

•

Labor costs and staffing were provided by the District.

•

Annual UV lamp replacement and disposal costs were based on service contracts with

the UV manufacturer.

• Redundancy

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o Contact chambers

■

Ozone – multiple channels were used in a single tank to meet peak flow.

No redundant tank necessary.

■

UV – multiple channels were used to meet the effluent limit at peak flow

with one channel out of service.

o Equipment

■

All major equipment was designed to meet peak capacity with the

largest unit out of service.

Filtration

The effluent disinfection cost estimates for each of the three District WRPs includes sand

filtration. This is included as a potential unit process for effluent pretreatment prior to

disinfection. However, in the opinion of the task force, it is not possible to reach a conclusion

regarding whether filtration should be part of the final design of a UV or ozonation disinfection

system for the three WRPs until additional laboratory and/or pilot plant testing is conducted.

Removal of additional total suspended solids (TSS) from the effluent of the District's three

major WRPs plants by filtration could have the following possible benefits for the UV and

ozone disinfection processes:

Removal of pathogenic microorganisms associated with suspended solids which would

be more resistant to inactivation by ozone and would not be inactivated by UV light

radiation;

Reduction of maintenance and operation costs; and

Reduction in the required UV and ozone dosage and thus reduction in the capital and

operating costs for the disinfection system.

The task force believes that properly designed and operated ozonation and UV effluent

disinfection systems for the District's three major WRPs can meet the proposed UAA bacteria

water quality standards without filtration. However there may be capital and operating cost

benefits for filtration. These benefits can be determined through laboratory and/or pilot plant

testing. Therefore, laboratory and pilot plant tests are recommended by the task force to

determine whether filtration is a cost-effective addition to the disinfection alternatives.

Since it is unclear whether filtration should be included as part of the UV and ozone

disinfection systems, the associated costs for the filtration facilities have been presented as

separate line items. Table 1.26 shows the probable cost opinions with filtration. Table 1.27

shows the probable cost opinions without filtration.

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Low Lift Pump Station

A low lift pump station is included for all three facilities to enable flow through the disinfection

and filter systems. It is assumed that low lift pumps will also be required even if filters are not

provided in order to accommodate high levels in the receiving streams.

North Side WRP

Ultraviolet Disinfection

Background

The North Side WRP (NSWRP) is rated at a capacity of 333 MGD design average flow and

450 MGD of design maximum flow. Flows above 450 mgd are diverted to the Tunnel and

Reservoir Plan system (TARP). Therefore 450 mgd is the design flow for sizing the UV

disinfection facilities. As presented in TM-5, the NSWRP permit limit for TSS is 12 mg/I under

monthly average conditions. These two parameters, along with the 65% UV transmittance as

stated previously, were used as the basis for sizing the UV disinfection facilities and obtaining

price quotes from equipment vendors. Table 1.11 presents the UV disinfection system sizing

for NSWRP.

TABLE 1.11

NSWRP – UV DISINFECTION SYSTEM SIZING DATA

Data

4 (3 operating, 1 standby)

UV Reactors Per Channel

UV Lamps Per Reactor

288

Total Number of Lamps

1,152

UV Channel Liquid Level Control

Motorized weir gate

Channel Dimensions

40.5' L x 8.1' W x 14.3' D

Total Power Requirement

2,764.8 kW

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As discussed earlier, a filtration facility has been included prior to the disinfection system.

Table 1.12 presents the filtration system sizing.

TABLE 1.12

NSWRP – TERTIARY FILTRATION SYSTEM SIZING DATA

Item

Data

Design Flow

450 MGD

Filter Loading at Peak Hourly, with

one filter unit (2 filter cells) out of

service

4.24* gpm/sq. ft.

Number of Filter Trains

Number of Filter Cells Per Train

Total Number of Filter Cells

Filter Area (each cell)

2,304 Sq.Ft.

Total Filter Area

92,160 Sq.Ft.

IRSSW recommends filter loading rates not to exceed 5 gpm/sf with one unit out of service under

peak hourly condition. Due to module design of filter cells, actual loading rates deviate from the

recommended loading rates.

Location on site

The NSWRP has very limited area for new facilities. Based on the location where the final

effluent discharges into the North Shore Channel, the disinfection facilities will be located in

the northeast corner of the plant. Combined final effluent from Battery A, B, C, and D will be

diverted into a wet well of a low-lift pump station just north of the proposed Filter Building.

From the pump station, final effluent will be pumped through the filters, and the filtered effluent

will then pass through the proposed UV channels by gravity. Motorized weir gates will be used

in the UV channels for level controls. A UV building will be provided for the UV channels and

for housing all electrical equipment such as power distribution centers and system control

centers. Disinfected effluent will be re-connected to the existing final effluent conduit for North

Shore Channel discharge. Figures 1.6 and 1.7 present an overall site plan and a partial site

plan for disinfection facilities based on UV disinfection. As shown from the figures, the

facilities will occupy most of the area available in the northeast part of the plant.

Site specific issues

Due to the space required for the filtration facility, available land east of the existing plant

fence (east of old railroad track where four radio towers are currently located) will be needed.

Construction of the UV disinfection facilities will create little interference with existing facilities

and operations. The only significant disruption to normal plant operation will occur during the

tie-in of the existing and the new effluent conduits to and from the disinfection facilities. This

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Figure 1.6

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Figure 1.7

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work will require by-pass pumping. Existing plant fence and the gas cylinder storage just north

of the Service Building will need to be relocated. Other construction will have minimal impacts

on the operation of the existing plant.

Cost Summary

Table 1.13 presents the opinion of probable costs for the UV disinfection facilities.

TABLE 1.13

NSWRP-OPINION OF PROBABLE COSTS FOR

UV DISINFECTION FACILITIES

Capital Cost Estimates

A. General Site Work

$ 4,000,000

B. Low Lift Pump Station

$ 54,000,000

C. Tertiary Filtration

$ 168,000,000

D. Disinfection System

$ 25,000,000

Total Capital Cost

$ 251,000,000

Operation and Maintenance Cost Estimates

A. General Site Work

$ 0

B. Low Lift Pump Station

$ 1,100,000

C. Tertiary Filtration

$ 2,300,000

D. Disinfection System

$ 3,200,000

Total Annual O&M Cost

$ 6,600,000

Total Present Worth O&M Cost

$ 128,000,000

Total Present Worth

$ 379,000,000

Annual Debt Services Cost

to UV disinfection, a peak flow of 450 mgd was used for sizing the ozone disinfection

facilities. Due to safety issues in transporting and difficulties in supplying such large amount of

liquid oxygen required for ozonation, the decision was made to use

On-site oxygen generation

for ozone disinfection. Table 1.14 presents system sizing for the ozone disinfection facilities

for NSWRP.

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TABLE 1.14

NSWRP – OZONE DISINFECTION SYSTEM SIZING DATA

Data

Number of Ozone Generators

8 (7 Operating, 1 Standby)

Ozone Capacity Per Generator

4,289 lbs/day

Oxygen Flow Rate Per Generator

448 SCFM

Total Oxygen Consumption

428,900 lbs/day

Total Power Requirement

6,272 kW

Cooling Water

830 GPM

On-site Oxygen Generation

Number of Vacuum Pressure Swing

Adsorption (VPSA) Units

Capacity Per VPSA Unit

100 tons/day

Contactor Tank Size

3.125 million gallons

Location on Site

Similar to the proposed location of UV disinfection facilities, the ozonation facilities will be

located in the northeast corner of the NSWRP where the final effluent conduit is located.

Combined final effluent from Battery A, B, C, and D will be diverted into a wet well of a low-lift

pump station just north of the proposed Filter Building. From the pump station, final effluent

will be pumped through the filters, and the filtered effluent will then pass through the proposed

ozone contactors by gravity.

The ozone disinfection system consists of an on-site oxygen generation system, ozone

generators, power supply units, and ozone destruction system. Vacuum Pressure Swing

Adsorption (VPSA) will be used for on-site oxygen generation. Ozone generators, power

supply units, ozone destruction units, and the associated electrical equipment such as local

control panels will be housed in the proposed Ozone Generation Building. The ozone

contactors will be constructed with all concrete. Similar to UV disinfection, disinfected effluent

from the ozone contactors will be re-connected to the existing final effluent conduit for North

Shore Channel discharge. Figures 1.8 and 1.9 present an overall site plan and a partial site

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Figure 1.8

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Figure 1.9

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plans for the ozone disinfection facilities. As shown from the figures, the facilities will occupy

almost all of the vacant area in the northeast corner of the plant.

Site Specific Issues

Oxygen generation presents several new challenges at the NSWRP. Oxygen is flammable

and a very strong oxidizer. The chemical processing industry has developed procedures for

designing safe plants and ensuring safe operation of oxygen generation facilities, but the on-

site generation of oxygen still presents new challenges to plant staff. For such a large on-site

oxygen generation plan, extensive training will likely be required for the District staff to develop

familiarity with the procedures for operating and maintaining the oxygen generation equipment

and to become accustomed to the necessary safety procedures.

Disruption to normal plant operation will occur during the tie-in of the existing and the new

effluent conduits to and from the disinfection facilities. This work will require by-pass pumping.

Existing plant fence and the gas cylinder storage just north of the Service Building will need to

be relocated. Other construction will have minimal impacts on the operation of the existing

plant.

An estimated 10 to 12 MVA of transformer capacity is required to provide electric service for

the ozone disinfection facilities. As the existing substation transformers do not have sufficient

excess capacity for this additional load, new transformers will be required and were included in

the cost estimate.

Cost Summary

Table 1.15 presents the opinion of probable costs for the ozone disinfection facilities.

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TABLE 1.15

NSWRP-OPINION OF PROBABLE COSTS FOR

OZONE DISINFECTION FACILITIES

Capital Cost Estimates

OZONE

A. General Site Work

$ 8,000,000

B. Low Lift Pump Station

$ 54,000,000

C. Tertiary Filtration

$ 168,000,000

D. Disinfection System

$ 100,000,000

Total Capital Cost

$ 330,000,000

Operation and Maintenance Cost Estimates

A. General Site Work

$ 0

B. Low Lift Pump Station

$ 1,100,000

C. Tertiary Filtration

$ 2,300,000

D. Disinfection System

$ 6,400,000

Total Annual O&M Cost

$ 9.800,000

Total Present Worth O&M Cost

$ 190,000,000

Total Present Worth

$ 520,000,000

Debt Services Cost

($ 28,000,000)

Stickney WRP

Ultraviolet Disinfection

Background

Ultraviolet (UV) light can be utilized for effluent disinfection with or without upstream filtration,

depending on effluent turbidity and extent of disinfection required to meet the assigned effluent

limitation. For UV equipment sizing and costing purposes, it was assumed that filtration was

not in place. The basis of design for the UV facilities is summarized in Table 1.16. The

Stickney WRP permit limit of 12 mg/I of TSS under monthly average condition has also been

considered for UV sizing. The UV facilities must be sized for the peak hydraulic flow rate,

whereas operation and maintenance costs are based on the average flow rate and hours/year

that the disinfection facilities will be operated. The Stickney WRP is significantly impacted by

the pumpback from the TARP and, once the McCook Reservoir is on-line, the plant will

operate at or near capacity for extended periods. For costing purposes, a future annual

average flow of 1,000 mgd was assumed.

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TABLE 1.16

SWRP – UV DISINFECTION SYSTEM SIZING DATA

Data

UV Reactors Per Channel

UV Lamps Per Reactor

240

Total Number of Lamps

2,880

UV Channel Liquid Level Control

Motorized weir gate

Channel Dimensions

40.5' L x 9.0' W x 14.3' D

Total Power Requirement

9,216 kW

For the purposes of costing, the UV equipment and facility layouts are based on the

experience of reputable manufacturers and installations elsewhere of similar scope, although

no other facility is of similar size to the Stickney WRP. To achieve the required capacity for

Stickney, multiple process trains would be required.

For the Stickney WRP, the UV facility would likely consist of a single structure, housing all of

the required ancillary equipment along with the channels where the flow passes between the

UV lamps. The channels are planned to be constructed of concrete, with influent and effluent

channels at the ends. Sluice gates will be used to control flow into each channel, with weirs

controlling the flow out of each channel. Major pieces of equipment include the electrical

power supply and distribution system and the UV lamps. Flow splitting would be required to

evenly distribute the flow between the multiple channels, along with flow meters or other flow

measuring devices. It was assumed that all of the channels and equipment would be located

indoors to facilitate maintenance and replacement of the UV lamps, which must be performed

on an annual basis. The structure would be a single-story building overlying the UV channels,

with architectural features to match the existing facades of nearby buildings.

The UV equipment is quite power intensive, and would require a new electrical substation,

drawing power from the Main Switch Gear Building nearby. New feeders and step-down

transformers would be required to power the new UV facility. In general, all of the channels

would be in operation most of the time; however, the lamp intensity would be modulated to

meet the flow conditions, thereby reducing overall power consumption.

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Location on Site

Due to the limited space available near the existing plant outfall and the large space

requirements for the new disinfection and related facilities, the UV disinfection facility would

have to be located to south of the planned Southwest primary clarifiers and west of the Main

Switch Gear Building, in the extreme southwest comer of the plant site, as shown on Figures

1-10 and 1-11. Except for several large interceptor sewers, this portion of the plant site is

mostly unused at this time.

Site Specific Issues

Preliminary hydraulic calculations indicate that, even without filtration, pumping would be

required to ensure that plant effluent could discharge to the Sanitary and Ship Canal under all

flow conditions. Therefore, effluent would be diverted just upstream of the existing outfall and

routed through a new effluent conduit to a low lift pumping station. After pumping, the effluent

would flow by gravity through the filters and UV disinfection facility, before being discharged to

the Sanitary and Ship Canal via a new outfall.

A new junction chamber would be constructed around the existing outfall conduit, with flow

control gates to divert the flow into the new conduit. The effluent conduit would be routed

under the rail lines to a location north and west of the Main Switch Gear Building, using an

inverted siphon under-crossing of the Northwest Interceptor Sewer, and connecting directly to

the new low lift pumping station.

The low lift pumping station would act in a similar role as the current West Side and Southwest

side influent pumping stations–that is a relatively low lift, high capacity application. For

purposes of preliminary costing, a smaller footprint facility with vertical turbine/propeller pumps

was assumed. This pumping station capacity would meet the flows indicated in the table

above.

Effluent filtration may be required at some point in the future if a high degree of disinfection

and/or nutrient removal is necessary. For facility sizing and costing purposes, shallow-depth

sand media filters with conventional loading rates were assumed. The basis of design for the

filtration facilities is summarized in Table 1.17. Hydraulic and space needs were considered in

laying out the facilities. Filtration may not be required initially. Therefore, the low lift pumping

station would be designed such that future hydraulic conditions could be met by changing the

pump impellers and, possibly, the pump motors. This would reduce the current required head

on the pumps, significantly reducing the electrical power consumption.

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Figure 1.10

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Figure 1.11

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TABLE 1.17

SWRP – TERTIARY FILTRATION SYSTEM SIZING DATA

Item

Data

Design Flow

1,440 MGD

Filter Loading at Peak Hourly, with

one filter unit (2 filter cells) out of

service

4.34* gpm/sq. ft.

Number of Filter Trains

Number of Filter Cells Per Train

Total Number of Filter Cells

120

Filter Area (each cell)

2,304 Sq.Ft.

Total Filter Area

276,480 Sq.Ft.

IRSSW recommends filter loading rates not to exceed 5 gpm/sf with one unit out of service under

peak hourly condition. Due to module design of filter cells, actual loading rates deviate from the

recommended loading rates.

Disinfection would follow filtration, and would be the final unit process prior to discharge from

the plant. Because the disinfection facilities are located on the far southwest corner of the

plant, continued use of the existing outletl would be impractical. Therefore, a new outfall was

assumed. This new outfall would be west of the existing Northwest Interceptor outfall to avoid

a second under-crossing of this older sewer. Alternatively, to avoid constructing an additional

outfall, the NW Interceptor outletl could possibly be modified or reconstructed to act as the

new plant outfall.

The new disinfection and related facilities would be located close to the existing Main Switch

Gear Building, the source for all power at the Stickney WRP site. An extension of the existing

high voltage switch gear will be required to meet the substantially increased power load

associated with these new facilities. New high voltage cable in conduit would be needed to

feed the new step-down transformers near the new facilities, along with a new switch gear

building.

Cost Summary

The opinion of probable construction cost for the UV disinfection alternative is presented in

Table 1.18. This opinion was prepared based on the concepts presented above and as shown

on the figures herein. A detailed breakdown of the opinion of probable construction cost is

included in the Appendix. The Operation and Maintenance Cost Estimates are also presented

in Table 1.18.

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TABLE 1.18

SWRP-OPINION OF PROBABLE COSTS FOR

UV DISINFECTION FACILITIES

Capital Cost Estimates

A. General Sitework

$93,000,000

B. Low Lift Pumping Station

$174,000,000

C. Tertiary Filtration

$642,000,000

D. Disinfection System

$91,000,000

Total Capital Cost

$1,000,000,000

Operation

Maintenance Cost Estimates

A. General Sitework

B. Low Lift Pumping Station

$4,100,000

C. Tertiary Filtration

$4,200,000

D. Disinfection System

$8,500,000

Total Annual O&M Cost

$16,800,000

Total Present Worth O&M Cost

$326,000,000

Total Present Worth

$1,326,000,000

Annual Debt Service Cost

($84,000,000)

Ozone Disinfection

Background

The bases of design for the ozone disinfection facilities are summarized in Table 1.19. The

ozone facilities must be sized for the peak hydraulic flow rate, whereas operation and

maintenance costs are based on the average flow rate and the hours/days per year that the

disinfection facilities will be operated. The Stickney WRP is significantly impacted by the

pumpback from TARP and, once the McCook Reservoir is on-line, the plant will operate at or

near capacity for extended periods. For costing purposes, a future annual average flow of

1,000 mgd was assumed.

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TABLE 1.19

SWRP – OZONE DISINFECTION SYSTEM SIZING DATA

Data

Number of Ozone Generators

24 (20 Operating, 4 Standby)

Ozone Capacity Per Generator

4,003 lbs/day

Oxygen Flow Rate Per Generator

437 SCFM

Total Oxygen Consumption

960,770 lbs/day

Total Power Requirement

27,216 kW

Cooling Water

908 GPM

On-site Oxygen Generation

Number of Vacuum Pressure Swing

Adsorption (VPSA) Units

Capacity Per VPSA Unit

150 tons/day

Contactor Tank Size

10 million gallons

For the purposes of costing, the ozone equipment and facility layouts are based on the

experience of reputable manufacturers and installations elsewhere of similar scope, although

no other facility is of similar size to the Stickney WRP. To achieve the required capacity for

Stickney, multiple process trains would be required.

For the Stickney WRP, the ozone disinfection facilities would likely consist of two separate

buildings. The Ozone Generator Building would house the ozone generating equipment and

the ozone destruct units, and would probably be constructed above the ozone contactors. A

separate Oxygen Generation Facility building would house the vacuum pressure swing

adsorption (VPSA) equipment to convert air to a high concentration oxygen stream, which

would be fed to the nearby ozone generating equipment. The high concentration ozone

stream would be dissolved in the effluent using diffusers located on the floor of the concrete

ozone contactor tanks. Unused ozone in the off gases would be collected and sent to an

ozone destruct catalyst in order to prevent free ozone from discharging into the atmosphere.

Other major pieces of equipment include the electrical power supply and distribution system.

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Flow splitting would be required to evenly distribute the flow between the multiple contact

tanks, along with flow meters or other flow measuring devices. It was assumed all of the

equipment would be located indoors, to provide easy maintenance. The Ozone Generator

Building would be a one story building mostly overlying the ozone contactor tanks below, with

architectural features to match the existing facades of nearby buildings. The Oxygen

Generation Facilities would typically be a vendor supplied facility, including the building and all

required equipment.

As the ozone equipment is very power intensive, a new electrical substation would be

required, drawing power from the Main Switch Gear Building nearby. New feeders and step

down transformers would be required to power the new ozone facilities. In general, all of the

ozone contactors would be in operation most of the time; however, the ozone flow could be

modulated to meet the required concentration, thereby reducing overall power consumption.

Location on Site

Due to the limited space available near the existing plant outfall and the large space

requirements for the new disinfection and related facilities, the ozone disinfection facilities

would have to be located to south of the planned Southwest primary clarifiers and west of the

Main Switch Gear Building, in the extreme southwest comer of the plant site, as shown on

Figures 1-12 and 1-13. Except for several large interceptor sewers, this portion of the plant

site is mostly unused at this time.

Site Specific Issues

The site specific issues associated with the ozone disinfection facilities would be similar to

those described for the UV disinfection facilities above. The low lift pumping station would be

required regardless of whether filtration is constructed.

Cost Summary

The opinion of probable construction cost for the ozone disinfection alternative is presented in

Table 1.20. This opinion was prepared based on the concepts presented above and as shown

on the figures herein. A detailed breakdown of the opinion of probable construction cost is

included in the Appendix. The Operation and Maintenance Cost Estimates are also presented

in Table 1.20.

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Figure 1.12

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Figure 1.13

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TABLE 1.20

SWRP-OPINION OF PROBABLE COSTS FOR

OZONE DISINFECTION FACILITIES

Capital Cost Estimates

OZONE

A. General Sitework

$97,000,000

B. Low Lift Pumping Station

$174,000,000

C. Tertiary Filtration

$642,000,000

D. Disinfection System

$226,000,000

Total Capital Cost

$1,139,000,000

Operation

Maintenance Cost Estimates

A. General Sitework

B. Low Lift Pumping Station

$4,100,000

C. Tertiary Filtration

$4,200,000

D. Disinfection System

$14,900,000

Total Annual O&M Cost

$23,200,000

Total Present Worth O&M Cost

$451,000,000

Total Present Worth

$1,590,000,000

Annual Debt Service Cost

($95,000,000)

Calumet WRP

Ultraviolet Disinfection

Background

The main components of the ultraviolet disinfection facilities for the Calumet WRP include the

UV disinfection building (containing UV reactors in channels), tertiary filtration system, and low

lift pump station. Critical plant flow rates used as a basis for sizing components and for the

development of capital costs and annual O&M costs are:

•

Average day flow – 305 mgd

•

Maximum day flow – 480 mgd

Disinfection at the Calumet WRP has been based on the need to meet an anticipated effluent

limit of 1,030 e.coli/100m1. The Calumet permit limit for TSS is 15 mg/I (monthly average).

This limit along with the 65% UV transmittance was used to size the UV disinfection system.

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System sizing data for the UV disinfection system is as shown in Table 1.21.

TABLE 1.21

CALUMET WRP — UV DISINFECTION SYSTEM SIZING DATA

Data

4 (3 operating, 1 standby)

UV Reactors Per Channel

UV Lamps Per Reactor

308

Total Number of Lamps

1,232

UV Channel Liquid Level Control

Motorized weir gate

Channel Dimensions

39.5' L x 8.83' W x 13.8' D

Total Power Requirement

3181 kW

The UV channels are planned to be constructed of concrete within an influent and effluent

channel on either end of the UV channels. Sluice gates at the head end of the UV channels

will be used to control flow to the channels. The UV channels are proposed to be housed

within a building enclosure, with additional building space provided for mechanical building

systems equipment and electrical equipment associated with the disinfection system. The

anticipated land area requirement for the UV system is 80 feet by 100 feet.

Sizing data for the proposed tertiary filtration system is included in Table 1.22.

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TABLE 1.22

CALUMET WRP — TERTIARY FILTRATION SYSTEM SIZING DATA

Item

Data

Design Flow

480 MGD

Filter Loading at Peak Hourly, with

one filter unit (2 fitter cells) out of

service

4.52* gpm/sq.ft.

Number of Filter Trains

Number of Filter Cells Per Train

Total Number of Filter Cells

Filter Area (each cell)

2,304 Sq.Ft.

Total Filter Area

92,160 Sq.Ft.

* IRSSW recommends filter loading rates not to exceed 5 gpm/sf with one unit out of service under

peak hourly condition. Due to module design of filter cells, actual loading rates deviate from the

recommended loading rates.

The resulting filter facility is anticipated to occupy an area of approximately 280 feet by 550

feet. Building space within the filter enclosure to house associated mechanical and electrical

equipment has been allowed. To accommodate the filter backwash, a dedicated conduit was

included to return the backwash flow to the Calumet WRP influent pump station as an internal

plant recycle flow. To provide gravity flow to the filters within the plant's existing hydraulic

grade line the filters are being proposed to be constructed mostly below existing plant grade.

The low lift pump station will be utilized to lift the filtered effluent to the disinfection system.

The pumping capacity would be sufficient to pump the maximum day flow of 480 mgd. The

pump station is estimated to occupy a space of approximately 100 feet by 160 feet. New

pressure conduits have been included to convey the filtered effluent to the disinfection system.

Electrical energy costs for the station have been based on the average day flow and an

anticipated static lift of approximately 25 feet.

Location on Site

At the Calumet WRP, secondary effluent flows from the five secondary treatment and

nitrification batteries, referred to as Batteries A, B, C, El and E2, to the southwest corner of

the plant site and through an outfall conduit to the Little Calumet River. Secondary effluent

from Batteries A, B, and C is collected in a conduit system and conveyed to Control Structure

No. 5 which is located at the southwest corner of the plant site. From Control Structure No. 5,

Battery A, B and C secondary effluent can be routed to the plant outfall or to the existing

chlorine contact chambers. Secondary effluent from Batteries El and E2 is routed through a

conduit system to the existing 12' x12' conduit between Control Structure No. 5 and the

chlorine contact chambers, from where it can be routed either to the contact tank structure or

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through Control Structure No. 5 to the plant outfall with secondary effluent from the other three

batteries. While the chlorine contact chambers are not currently used for disinfection

purposes, secondary effluent is typically routed through the tank and on to the outfall conduit.

Alternatively, existing gate structures at the chlorine contact chambers can be closed and all of

the plant effluent flow can be routed directly to the plant outfall through Control Structure No.

5, bypassing the contact tank.

For planning purposes it has been assumed that the area currently occupied by the chlorine

contact chambers and the unused open area on the south side of the main plant road would

be utilized for the proposed ultraviolet disinfection system and associated filtration system and

low lift pump station. Figure 1.14 and Figure 1.15 are site plans which illustrate the proposed

location of these facilities.

The existing chlorine contact chambers would be demolished while the inlet structure to the

chlorine chambers would be maintained to allow for flow control during construction and then

ultimately to route flow to the new facilities. A new conduit would be installed to convey the

secondary effluent flow from the chlorine chambers inlet structure to the tertiary filtration

system. Flow through the filters would be by gravity. The filtered effluent would then be

pumped by a new low lift pump station to the UV disinfection system, allowing gravity flow

through the disinfection system and a new conduit conveying the disinfected effluent back to

the existing plant outfall conduit.

Site Specific Issues

Site specific issues associated with the potential implementation of a UV disinfection facilities

at the Calumet WRP are outlined below:

•

Demolition of the existing chlorine contact chambers would be required.

•

Existing chlorine contact chambers influent and effluent control structures would be

salvaged and utilized for bypassing of the chlorine chambers during its demolition.

•

Conduit tie-ins to the existing chlorine chambers influent structure and to the existing

outfall conduit would need to be constructed.

•

Plant perimeter security fencing would be extended to enclose the new facilities.

•

Screening of the proposed new facilities from 130

Street may be determined to be

necessary by the District.

•

Electrical power is delivered to the Calumet WRP from the local utility through the two

existing transformers and the 13.2 KVA switchgear located in the existing switchgear

building at the northwest corner of the plant site. Two new circuit breakers will be

required to be installed in the existing switchgear. A large electrical ductbank would

need to be extended from the substation approximately 2,500 feet south to the

proposed facilities. Ductbank routing issues, such as conflicts with existing utilities

may result.

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Figure 1.14

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Figure 1.15

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•

The substantial power requirements of the disinfection facilities will likely consume the

remaining available capacity of the existing transformers. In addition a cooling fan

package my be required to increase the capacity of the transformers.

•

The start-up of large motors at the Calumet WRP reportedly results in a voltage drop of

approximately 10%. The equipment manufacturers have indicated that such voltage

swings can be accommodated.

•

Periodic, high flow rate recycle flows will result from backwashing of tertiary filters

requiring a dedicated conduit to convey the recycle flow to the head end of the Calumet

WRP. Although the Harvey Interceptor sewer is located near the proposed filtration

system, it does not appear that this sewer has the reserve capacity to accept this

recycle flow rate.

•

The currently unused open area at the southwest corner of the plant site that is

identified for use for possible construction of disinfection facilities may contain wetland

areas. A determination regarding the presence of wetlands and actions required if

wetlands are proposed to be disturbed, needs to be addressed by the District. At this

time no cost associated with this issue have been included in the capital cost estimate.

Cost Summary

Table 1.23 presents an opinion of probable capital costs itemized for general sitework, the low

lift pump station, tertiary filtration, and the UV disinfection system. In addition, estimated

annual operation and maintenance costs are shown for each component and as a total annual

cost. Present worth of the total annual O&M costs, total present worth, and the annual debt

service cost are also reflected in Table 1.23.

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TABLE 1.23

CALUMET WRP — OPINION OF PROBABLE COSTS

FOR UV DISINFECTION FACILITIES

Capital Cost Estimates

A. General Site Work

$14,000,000

B. Low Lift Pump Station

$ 59,000,000

C. Tertiary Filtration

$ 208,000,000

D. Disinfection System

$ 31,000,000

Total Capital Cost

$ 310,000,000

Operation and Maintenance Cost Estimates

A. General Site Work

$ 0

B. Low Lift Pump Station

$ 1,700,000

C. Tertiary Filtration

$ 2,300,000

D. Disinfection System

$ 3,100,000

Total Annual O&M Cost

$ 7,100,000

Total Present Worth O&M Cost

$ 138,000,000

Total Present Worth

$ 448,000,000

Annual Debt Services Cost

($ 26,000,000)

Ozone Disinfection

Background

The main components of the ozone disinfection facilities would include the ozone generator

building, oxygen generation plant (vacuum pressure swing adsorption, VPSA), ozone

contactor, tertiary filtration system, and low lift pump station. Critical plant flow rates used as a

basis for sizing components and for the development of capital costs and annual O&M costs

are:

•

Average day flow — 305 mgd

•

Maximum day flow — 480 mgd

Disinfection at the Calumet WRP has been based on the need to meet an anticipated effluent

limit of 1,030 e.coli/100m1.

System sizing data for the ozone system is as shown in Table 1.24.

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TABLE 1.24

CALUMET WRP – OZONE DISINFECTION SYSTEM SIZING DATA

Data

Number of Ozone Generators

Ozone Capacity Per Generator

4,792 lbs/day

Oxygen Flow Rate Per Generator

500 CFM

Total Oxygen Consumption

468,055 lbs/day

Total Power Requirement

6,985 kW

Cooling Water

906 GPM

On-Site Oxygen Generation

Number of Vacuum Pressure Swing

(VPSA) Units

Capacity Per VPSA Unit

100 tons/day

Contactor Tank Size

4.8 million gallons

The facilities associated with the ozone system are proposed to be located in the area of the

existing chlorine contact chambers. The three main structures needed for the ozone system

and their approximate overall dimensions are the contact tank (100 feet by 230 feet), ozone

building to house the ozone generators and associated electrical and mechanical (building

services) equipment (100 feet by 140 feet), and the oxygen generation plant (150 feet by 150

feet).

The tertiary filters and low lift pump station associated with the ozone disinfection system

would be the same as required for UV disinfection and have been previously described in the

UV disinfection section. The flow routing between facilities would follow the same pattern as in

the UV disinfection facilities, filtration, low lift pump station, and disinfection.

Location on Site

For planning purposes it has been assumed that the area currently occupied by the existing

chlorine contact chambers and the unused open area on the south side of the main plant road

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would be utilized for the proposed ozone disinfection system and associated filtration system

and low lift pump station. Refer to Figures 1.16 and 1.17 which illustrate the proposed location

of these facilities.

The collection of secondary effluent at the Calumet WRP and routing of the secondary effluent

to the plant outfall conduit is described in the UV disinfection section. A new conduit would be

constructed to convey the secondary effluent flow from the chlorine chambers inlet structure to

the tertiary filtration system. Flow through the filters would be by gravity. The filtered effluent

would then be pumped by a new low lift pump station to the ozone contactor, allowing gravity

flow through the contactor and a new conduit conveying the disinfected effluent back to the

existing plant outfall.

Site Specific Issues

Site specific issues associated with the ozone disinfection facilities would be the same as

those outlined in the UV disinfection section with additional considerations listed below:

•

Sound attenuation provisions may be necessary to control noise from the VPSA

oxygen plant and the resulting noise level at plant property line.

•

The electrical distribution system for the ozone facilities would require a new 13.2 KVA

double ended switchgear located locally at the new facilities.

•

An oxygen gas pipeline owned by Praxair exists along 130th

Street in front of the

Calumet WRP with an available service lateral to the plant. Preliminary discussions

with Praxair have indicated that the pipeline could support the needs of the Calumet

plant for ozone disinfection. Supply of oxygen gas from the pipeline versus

construction of an on-site oxygen generation system may be an option that the District

can pursue with Praxair if ozone disinfection is to be implemented at Calumet. It is

possible that this may be a more cost-effective means of oxygen supply.

Cost Summary

Table 1.25 presents an opinion of probable capital costs itemized for general sitework, the low

lift pump station, tertiary filtration, and the ozone disinfection system. In addition, estimated

annual operation and maintenance costs are shown for each component and as a total annual

cost. Present worth of the total annual O&M costs, total present worth, and the annual debt

service cost are also reflected in Table 1.25.

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Figure 1.16

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Figure 1.17

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TABLE 1.25

CALUMET WRP — OPINION OF PROBABLE COSTS

FOR OZONE DISINFECTION FACILITIES

Capital Cost Estimates

A. General Site Work

$14,000,000

B. Low Lift Pump Station

$ 59,000,000

C. Tertiary Filtration

$ 208,000,000

D. Disinfection System

$ 110,000,000

Total Capital Cost

$ 390,000,000

Operation and Maintenance Cost Estimates

A. General Site Work

$ 0

B. Low Lift Pump Station

$ 1,700,000

C. Tertiary Filtration

$ 2,300,000

D. Disinfection System

$ 6,400,000

Total Annual O&M Cost

$ 10,400,000

Total Present Worth O&M Cost

$ 202,000,000

Total Present Worth

$ 592,000,000

Annual Debt Services Cost

($ 33,000,000)

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SUMMARY OF OPINIONS OF PROBABLE COST

As discussed previously, disinfection cost opinions for North Side, Stickney, and Calumet

WRP were developed based on a low-lift pump station, a filtration facility, and a disinfection

system. Filtration was included for both disinfection alternatives because of the uncertain

effects of TSS on disinfection efficiency. Table 1.26 presents a summary table of the opinion

of probable costs for both UV and Ozone disinfection facilities for the three WRPs, including

filtration.

TABLE 1.26

OPINION OF PROBABLE COSTS OF UV AND OZONE DISINFECTION FOR

NORTH SIDE WRP, STICKNEY WRP, AND CALUMET WRP

(WITH FILTRATION)

NORTH SIDE WRP

STICKNEY WRP

CALUMET WRP

Capital Cost Estimates, in

B. Low Lift Pump Station

$ 54

$174

$59

C. Tertiary Filtration

$ 168

$642

$208

D. Disinfection System

Operation and Maintenance Cost

Estimates, in millions

A. General Site Work

$ 0

B. Low Lift Pump Station

$ 1.1

$4.1

$1.7

C. Tertiary Filtration

$ 2.3

$4.2

$2.3

D. Disinfection System

Total Annual O&M Cost*

Present Worth O&M Cost

Total Present Worth, in millions

Annual Debt Services Cost, in

millions**

21)

28)

($84)

($95)

($26)

($33)

TotalAnnual?

Cost is basedon current electricity rate at 0.075 per kilowatt-hour. This cost will change

accordingly should the electricity rate increase in the future

*" Based on interest rate of 5.5% for 20 years.

As shown from Table 1.26, filtration facilities contribute more than half of the probable

construction costs for all three WRPs. Since it is uncertain if filtration will be needed prior to

either one of the disinfection alternatives, Table 1.27 presents a summary of the opinion of

probable costs for both disinfection alternatives

without

filtration.

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TABLE 1.27

OPINION OF PROBABLE COSTS OF UV AND OZONE DISINFECTION FOR

NORTH SIDE WRP, STICKNEY WRP, AND CALUMET WRP

(WITHOUT FILTRATION)

NORTH SIDE WRP

STICKNEY WRP

CALUMET WRP

Capital Cost Estimates, in

B. Low Lift Pump Station

$ 54

$174

$59

C. Disinfection System

Operation and Maintenance Cost

Estimates, in millions

A. General Site Work

$ 0

B. Low Lift Pump Station

$ 1.1

$4.1

$1.7

C. Disinfection System

Total Annual O&M Cost*

Total Present Worth O&M Cost

Total Present Worth, in millions

Annual Debt Services Cost, in

millions

($ 7)

14)

($30)

($42)

($9)

($15)

TotalAnnual?

Cost?

based on current electricity rate at $0.075 per kilowatt-hour. This cost will change

accordingly should the electricity rate increase in the future

** Based on interest rate of 5.5% for 20 years.