Treatment of Cercla (Comprehensive Environmental Response, Compensation, and Liability Act) Leachates by Carbon-Assisted Anaerobic Fluidized Beds

Two anaerobic granular activated carbon (GAC) expanded-bed bioreactors were tested as pretreatment units for the decontamination of hazardous leachates containing volatile and semivolatile synthetic organic chemicals (SOCs). The different characteristics of the two leachate feed streams resulted in one reactor operating in a sulfate-reducing mode and the second in a strictly methanogenic environment. Both reactors were operated with a 6-hr unexpanded empty-bed contact time and achieved SOC removal acceptable for pretreatment units. In both reactors, the majority of the SOCs were removed by biological activity, with GAC adsorption providing stability to each system by buffering against load fluctuations.