What Now!: Emissions Monitoring and Control in Collection Systems

It takes a thorough understanding of the inlet odorous characteristics from a complex wastewater collecting system interceptor network of a very large city like Los Angeles to determine the type of technology necessary to comply with hydrogen sulfide (H2S) and total volatile organic compounds (VOCs) permit discharge limits. The City of Los Angeles (City) has an extensive collection system that is over 6,000 miles (9700km) in length and consists of shallow and deep pipes, drop structures and inverted siphons across eight major interceptors. Owners, like the City, are experienced and comfortable with vapor phase H2S control systems for extracted collection system odorous air streams, but complying with total VOCs, total non-methane hydrocarbon (TNMHC) limits provides a wrinkle that represents unchartered territory for most agencies. The first challenge is in understanding the analytical approaches to quantifying total VOCs/TNMHCs and making sure the results from those procedures are consistent with the applicable discharge permit requirements. In this case earlier testing suggested they were not, and so separate independent speciated procedures were required. The second challenge was evaluating and identifying proven technologies that could consistently remove H2S and total VOCs/TNMHCs to levels that would comply with permit limits.