Treatment of a high-strength sulphate-rich alkaline leachate using an anaerobic filter

摘要

The research looks at the feasibility of treating an alkaline sulphate-rich leachate arising from the co-disposal of municipal solid waste with cement kiln dust by means of an anaerobic filter (AF). This type of leachate with a high sulphate concentration is commonly prohibited for discharge to sewer and requires an on-site treatment solution. The AF used had a working volume of 41 and contained reticulated polyurethane foam as the biomass support material. The filters were operated over a 152 day experimental period during which the COD loading onto the filter was increased from 0.76 to 7.63 kg COD m~(-3) d~(-1). In the early stages of operation at low loading, soluble sulphides accumulated that inhibited methanogenic activity. This was restored by dosing FeCl_3 to the reactor. The continued dosing allowed efficient COD removal of between 75 percent and 90 percent until the nominal retention time in the reactor was 3 days, at which point reactor performance declined significantly. The main mechanism for COD removal was by sulphate-reducing bacteria, which also resulted in up to 88 percent sulphate removal from the leachate. The average methane generation rate was 0.101 g~(-1) COD removed. The results indicate the potential for using this approach as a pre-treatment that could significantly reduce the COD load to a second stage treatment process, but problems associated with the implementation of the technology at a larger scale have been identified.