Rg~~JVED
CLERK’S OFFICE
BEFORE THE ILLINOIS POLLUTION CONTROL BOARD
APR 112002
IN THE MATTER OF:
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Pollution
STATE OF
Control
IWNOIS
Board
WATER QUALITY TRIENNIAL REVIEW
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R02-1 I
AMENDMENTS TO 35 ILL. ADM. CODE
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(Rulemaking-Water)
302.208(c)-(g), 302.504(a),
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302.575(d), 303.444, 309.141(h);
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AND PROPOSED 35 ILL. ADM. CODE
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301.267, 301.313, 301.413,
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304.120 AND 309.157
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COMMENTS OF THE THORN CREEK BASIN SANITARY DISTRICT
The Thorn Creek Basin Sanitary District submits the following comments in support of the
proposed amendment to 35 ILL. Adm. Code 304.120.
The Illinois Environmental Protection Agency (“Agency”) is proposing to amend 35 ILL. Adm. Code
304. 120 of the Board regulations by adding a Paragraph (g) which specifies that compliance with the 5-
day biochemical oxygen demand (BOD5) numerical standards in Section 304.120 be determined by
analysis of 5-day carbonaceous biochemical oxygen demand (CBOD5).
The District supports the proposed amendment to Section 304.120. The BOD5 test was
developed to measure the biodegradable organic matter in wastewater, since there was no easy way to
directly measure biodegradable organic matter.
There are other materials that will interfere with the BOD5 test. The ammonia-nitrogen exerts a
so-called nitrogenous demand (NOD) when it is biologically converted to nitrate-nitrogenthrough bacterial
action Before 1970, treatment plants were not required to nutnfy When the BOD5 test was run on
secondary treatment effluents, only a minor amount of NOD would have been measured in the BOD5 test.
The current BOD5 limits were developed using pre 1970 data and assuming BOO5 test results were free
of NOD. Once treatment plants began to nitrify, the amount of NOD measured in the BOO5 test increased
significantly. The NOD interference produced BOD5 results that indicated the presence of much higher
amounts of biodegradable organic matter than was actually present. The CBOD5 test removes the NOD
interference and restores the measurement to the Board’s original intention.
By formally recognizing the use of the CBOD5 test for measuring deoxygenating wastes under
Section 304.120, the Board will be making the regulation scientifically correctwith-regard-to-its method for
assessing the removal of organic matter in the secondary treatment process.
Any concerns which the Board may have regarding the removal of toxicity due to ammonia-
nitrogen from municipal wastewaterare handled adequately under Sections 304.105 and 304.122 of the
Boards regulations.
Thorn Creek Basin Sanitary District
By:_________
Jftes L Daughert~ant ager
April 10, 2002
I
Thorn Creek Basin Sanitary District
700 West End Ave.
Chicago Heights, IL 60411
708-754-0525