Recent California legislation required the City of Los Angeles to prepare air toxics emissions inventories at its four wastewater treatment plants. This paper presents the results of these inventories, including descriptions of available estimation methods, rationale for method selection, intercomparisons of available methods, and comparisons of emissions by treatment plants. Results of required health risk assessments are also discussed. Observations on the emission inventory process at wastewater treatment plants are offered.zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA Water Environ. Res., 66, 140(1994).

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This research study was undertaken to enhance the efficiency and economy of carbon scrubbers in controlling odors and volatile organic compounds (VOCs) at the wastewater collection and treatment facilities of the Bureau of Sanitation, City of Los Angeles. The butane activity and hydrogen sulfide breakthrough capacity of activated carbon were assessed. Air streams were measured for odorous gases and VOCs and removal efficiency (RE) determined. Carbon towers showed average to excellent removal of odorous compounds, VOCs, and siloxanes; whereas, wet scrubbers demonstrated good removal of odorous compounds but low to negative removal of VOCs. It was observed that the relative humidity and empty bed contact time are one of the most important operating parameters of carbon towers impacting the pollutant RE. Regular monitoring of activated carbon and VOCs has resulted in useful information on carbon change‐out frequency, packing recommendations, and means to improve performance of carbon towers.

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The goal of this research study is to enhance the efficiency and economy of carbon scrubbers in controlling odors and VOCs at the wastewater collection and treatment facilities of Bureau of Sanitation, City of Los Angeles. The objectives are: 1) to use carbon life expectancy and breakthrough methods for monitoring carbon towers; 2) to reduce harmful impacts of pollutants on public health and the environment; 3) and to recommend efficient active carbon application.The butane activity and hydrogen sulfide breakthrough capacity of activated carbon were assessed. Air streams were measured for odorous gases and VOCs. Single-stage wet scrubbers at some wastewater treatment processes, while removing moderate levels of reduced sulfur compounds, showed low to negative removal of VOCs when compared to carbon towers alone or in series. Regular monitoring of activated carbon has resulted in useful information on carbon change-out frequency and packing recommendations to enhance odor-and VOC-removal capacity.Angeles-Glendale Reclamation Plants process 66 mgd of wastewater to provide 16 mgd of tertiary treated reclaimed water that is used by a number of contract users.Odors and volatile organic compounds (VOCs) emitted from wastewater collection and treatment facilities of the BOS are not only environmental hazards and cause odor nuisances, but also threaten public health if emissions are not controlled.Due to the effective source control measures implemented by the municipalities, especially by the BOS, mass emissions contributed by the industrial and commercial users have decreased significantly over time. However, about 80% of the sewage treated at the largest facility is of domestic nature comprised of biological, pharmaceutical, and household chemical sources; therefore, the control of such emissions remains a formidable task. Hence, efficient control, sustained monitoring, and proper characterization of odorous emissions and VOCs at the wastewater collection and treatment plant systems are of utmost importance for not only reducing harmful impacts of pollutant emissions to the public, but also for the proper operation, maintenance, and sustainable management of such wastewater systems.WEFTEC 2010x Proactively monitor the operating conditions and the packing materials used in the scrubbers for reducing public exposure to odors and VOCs, andx Evaluate chemical and carbon scrubbers at liquid and solid processes based on the past odor complaints and suspected high VOC emissions and make cost-effective recommendations.WEFTEC 2010