Emissions of Volatile and Potentially Toxic Organic Compounds from Wastewater Treatment Plants and Collection Systems (Phase 2). Volume 4. Modeling Volatile Organic Compound Emissions during Preliminary and Primary Treatment

摘要

The purpose of this phase of the study was to develop models of VOC emissions that can be used to determine the importance of individual stages in the preliminary and primary operations sequence. Included in the study was selection of candidate operations for design or operational modification to minimize emission rates. Overall emissions predicted during preliminary and primary treatment were approximately 25% of influent VOC load and varied from 0.02 to 0.03 g-VOCs/cu m of wastewater treated, depending on the method of plant operation selected. Major losses occurred in aerated grit chambers and at the weirs. Losses from non-aerated tanks and conveyance channels were negligible relative to other units. Emissions predicted for headworks steps were small, but not negligible. Options to covering treatment units and collection of off-gases are clearly available in many cases. Submerged weirs, launder depth controls, and elimination of aeration are examples of modifications that can be used to effectively decrease VOC emissions.