A SLUDGE CHARACTERIZATION ASSAY FOR AEROBIC AND DENITRIFYING PHOSPHORUS REMOVING SLUDGE

It was recently recognized that denitrifying bacteria, as well as aero bic bacteria, contribute to the biological phosphorus removal process. For evaluation of the phosphorus removal process it is necessary to h ave tests enabling a proper characterization of the microbial populati on in the activated sludge. In this study we evaluated the possibility of anoxic phosphorus release or aerobic/anoxic phosphorus uptake test s for sludge characterization. Hereto we employed sludge mixtures of e nrichment cultures from laboratory sequencing batch reactor (SBR) syst ems operated under aanaerobic-aerobic (A/O) or anaerobic-anoxic (A2)co nditions. It is shown that interpretation of phosphorus release tests, with or without nitrate present, is difficult. On the other hand a co mparison of phosphorus uptake under aerobic and anoxic conditions lead s to a straightforward characterization of the microbial population in the phosphorus removing organisms, with respect to their phosphorus r emoval activity under aerobic and anoxic conditions. (C) 1997 Elsevier Science Ltd.