Designing a biofilter odor removal system for a sewage lifting station

BACKGROUND AND OBJECTIVESBiofiltration is an air pollution control technology that uses microorganisms to biodegrade odors and other volatile pollutants in waste air streams. Microorganisms exist on the surface and in the thin layer of water that surrounds the surface of the biofilter material. During the biofiltration process, polluted air slowly passes through the biofilter bed. Pollutants are absorbed on the surface of the substrate and penetrate into the water layer. Simultaneously, microorganisms consume it and produce energy, biomass and metabolic end products, mainly CO۲ and H۲O. Biological air filtration is performed in special bioreactors, i.e., biofilters (BF), bio-trickling filter (BTF), bio-scrubbers (BS), which can remove a wide range of gaseous pollutants present in low concentrations in large amounts of air.MATERIALS AND METHODSIn this study, a biofilter system was designed to remove emitted odors (H۲S) from a sewage lifting station with a flow rate of ۶۵۰ m۳/h. This system includes ۲ tanks each with a capacity of ۱۰ m۳. The loading rate was ۱۰۰ m۲/m۳.h and the hydraulic retention time was ۸۳ seconds.The system is equipped with lignocellulosic media surface moistening system.RESULTS AND DISCUSSIONThe biofilter reactor inoculated with Thiobacillus spp. microbial fertilizer, activated sludge, working biofilter effluent and chicken manure are used. To increase the growth of sulfur-oxidizing microorganisms and biofilm formation, water containing mineral nutrients was used for several weeks. Under stable operating conditions, the concentration of H۲S was reduced from ۱۶ mg/L to less than ۱ mg/L (more than ۹۳% removal) .CONCLUSIONToday, biofiltration is considered a half-century old technology that emerged in industry and is used in waste gas management and odour removal. In general, the presence of any type of chemical pollutant, even if their concentration is variable, biofiltration can guarantee the removal of more than ۵۰% of it. The lifetime of lignocellulosic media in biofilters is usually up to ۵ years.

کلیدواژه ها:

Biofilteration ، Odor removal ، Sewage lifting station ، Thiobacillus spp.