MTBE and BTEX biodegradation in a porous pot and a fluidized bed reactor.

摘要

Methyl tert-butyl ether (MTBE) is a gasoline additive used to improve air quality by reducing emissions. Unfortunately, MTBE has leaked from underground storage tanks into the groundwater and threatens drinking water supplies. The feasibility of biologically degrading methyl tert-butyl ether (MTBE) contaminated groundwater is dependent on the ability to degrade MTBE and its by-products in the presence of other gasoline contaminants. Benzene, toluene, ethylbenzene, and p-xylene (BTEX) is a combination of gasoline components often found in MTBE contaminated aquifers.; This study investigates the degradation of MTBE and BTEX by a porous pot reactor and a fluidized bed reactor (FBR). A mixed culture degraded both MTBE and BTEX in a continuous flow reactor with a biomass retention system (porous pot) at varying hydraulic retention times (HTRs). MTBE was degraded from 75 mg/L to less than 0.001 mg/L and each BTEX compound was degraded from 17 mg/L to less than 0.001 mg/L.; A culture in an aerobic FBR with granular activated carbon (GAC) as a biological attachment medium also degraded MTBE and BTEX. The FBR was run at varying empty bed contact times (EBCTs). At an empty bed contact time (EBCT) of one-hour, the MTBE effluent concentration averaged 0.0215 mg/L and each BTEX compound was at an effluent concentration below 0.003 mg/L. FBR performance decreased at shortened EBCTs but continued to degrade greater than 99% of all contaminants.; Batch experiments were conducted with the culture from the porous pot reactor and the culture attached to the GAC in the FBR to analyze the degradation kinetics of MTBE and BTEX.; Denaturing Gradient Gel Electrophoresis (DGGE) analysis monitored the culture in the porous pot and attached to the GAC at various stages of operation. Flavobacteria-Bacteriodes-Cytophaga, which are floc forming organisms, were observed in both the porous pot reactor and the FBR and appeared to adhere well to the GAC. Beta Proteobacteria were also observed, specifically organisms with a high similarity to PM-1, a known MTBE degrader.