Treatment of four industrial wastewaters by sequencing batch reactors: evaluation of COD, TKN and TP removal

This study investigated the ability of a sequencing batch reactor (SBR) system to treat four industrial wastewaters, namely, textile, landfill leachate, seafood and slaughterhouse effluents. The system employed three identical SBRs (10 l volume each) operating in parallel and each waste was treated one at a time. The operational variables examined included the length of the non-aerated period and the solids retention time (SRT). All four wastewaters experienced chemical oxyfen demand (COD) and total kjeldhal nitrogen (TKN) removals greater than 81%, while the TP removals were lower, ranging from 57 to 94%. The length of the non-aerated period appeared to have minimal effect on the SBR performance; however, increases in SRT reduced the percent TP removal for the textile and leachate wastes only. In addition, to investigate organic loading limits to the seafood SBR system, the COD was increased by three increments of 250 mg l(-1) starting from a baseline concentration of 1100 mg l(-1). This resulted in a reduction in both the TKN and TP removal at the higher concentrations. Finally, for the slaughterhouse wastewater, the COD:TKN ratio was tested at levels of 6:1, 8:1 and 9:1 with the result that only the TP removal was affected at the lowest ratio.