Report - Metropolitan Water Reclamation District of Greater Chicago

nitrogenous oxygen-demanding substances, and the volume of CSOs collected by the T ARP
systems.
Calculating pollution removal gives an indication of how well T ARP is serving its
function, since the pollutants diverted to T ARP would have otherwise been discharged into the
area waterways. The results of the calculations will be sent to M&O and also published in the
2010 EM&RD annual report in 2011.
Estimation of Emission of Hazardous Air Pollutants from Metropolitan Water
Reclamation District of Greater Chicago Water Reclamation Plants. Under Section 112 of Title
I of the Clean Air Act, a publicly owned treatment works (POTW) is considered a major source
of HAPs if it emits or has the potential to emit 10 tons per year or more of any HAP or 25 tons
per year or more of any combination of HAPs. As part of the NPDES permits and regulations
under the Clean Air Act, emission of HAPs from the wastewater treatment processes for each
WRP was estimated.
Estimation of the emissions of these HAPs from the wastewater treatment process units is
made using the Bay Area Sewage Toxics Emissions (BASTE) computer model developed by
CH2M Hill. According to the output from the BASTE model, all of the individual HAP
emissions were less than the 10 ton/year criterion at any District WRP. Toluene and
acetaldehyde were the predominant compounds emitted from the wastewater treatment processes
at the Stickney WRP. Carbon disulfide was the predominant compound emitted from the
Calumet WRP liquid stream. The total measured HAP emissions were substantially less than the
25 ton/year threshold at each of the three large WRPs. The wastewater treatment process units at
the District's WRPs are not a major source of HAPs.
Conducting Applied Research on Process Optimization and Evaluation of New
Technologies. The WTPR Section conducted the following applied research projects in 2010.
Characterization of Recycle Streams at the Stickney and Calumet Water Reclamation
Plants. In July 2008, the WTPR Section began sampling the recycle streams at the Stickney and
Calumet WRPs in order to evaluate the nutrient loads to the headwork contributed by these
recycle streams. The District does not routinely monitor flow of recycle streams or nutrient
contents in the recycle streams at either plant. However, grab samples are collected from certain
recycle streams for total and suspended solids analyses for process control information. The
parameters analyzed in this study have been chosen such that a range of nutrient treatment
strategies may be considered to address stricter nutrient regulations for TN and TP. Thus, the
characterization of nutrient loads in recycle streams will provide important information for
formulating the nutrient reduction strategies for both WRPs. Sampling for this project continued
through August 2009. The findings of the study were presented at the November 2010 M&R
seminar, which included the details of sampling plan, data, and a set of recommended
technologies for nutrient treatment and recovery based on the data collected. A final report
detailing this study will be completed in 2011.
22