WASTEWATER COLLECTION SYSTEM HYDROGEN SULFIDE AND VOC FATE MODEL

摘要

Odors from several municipal wastewater collection systems force mains and gravityrninterceptors are currently impacting residents and neighbors located near them. Also,rnhigh odor generation inside the interceptor is an excellent indicator of high corrosionrnareas. Recently, the U.S. Environmental Protection Agency (EPA) has beenrnrequesting information on hazardous air pollutants (HAPs) and volatile organicrncompounds (VOCs) emissions from collection systems. In addition, many publiclyrnowned treatment works (POTWs) will need to factor regulatory drivers, corrosionrnprevention, and/or odor controls into their strategies for collections systems that arernbeing built, rehabilitated, or updated to handle existing and future wastewater flows forrnthe next twenty years.rnSeveral POTWs assisted CH2M HILL to develop a predictive odor, HAPs, and VOCsrninterceptor system model to assess pollutant and corrosion impacts. This innovativernmodel (Interceptor Model) can estimate the concentrations of over 300 compoundsrnincluding hydrogen sulfide, ammonia, HAPs, and VOCs both in the sewer headspacernand in the liquid phase. The model determines air emissions by accounting for sulfiderngeneration or the compound抯 specific characteristic, oxidation, mass transfer acrossrnthe air/water interface, and liquid-phase bulk transfer.rnThis paper presents the Interceptor Model results for the collection systems for fourrnPOTWs. Odors and corrosion potentials were determined for each POTWs.rnRecommendations for controlling odors and corrosions are presented. HAPs andrnVOCs emissions modeling approaches are presented, but actual modeling and controlrnrecommendations are not included, pending further study and evaluation by thernPOTWs. This paper shows a very strong relationship between moderate to highrnhydrogen sulfide emissions and areas with high corrosion in the collection system.rnThese "hot spots" are areas that HAPs and VOCs could be emitted. Also, with as fewrnas 10 liquid-phase samples collected along any interceptor, the Interceptor Model canrnbe calibrated. In one case, the calibrated model was compared to a detailed interceptorrnodor/corrosion field sampling study that had collected over 2,000 liquid samples. Thernmodel抯 results were within 10 percent of the field study for hydrogen sulfide andrncorrosion.