Evaluation of extracellular biopolymer and its impact on bioflocculation in activated sludge bioreactors

摘要

The influence and dynamics of bacterial extracellular polysaccharide (EPS) polymer productionnand its impact on bioflocculation in activated sludge (AS) bench-scale reactors were investigated.nThe impact of food to microorganism ratio (F/M), reactor configuration and easily biodegradablencarbohydrates in influent streams on biological processes that support or weaken good flocnformation and the link with EPS quantity was studied. Bioreactors were run as either sequencingnbatch or continuous systems using wastewater media with glucose or acetate as C source inndifferent F/M ratios. EPS levels were quantified using mid-infrared spectroscopy which providedna rapid technique for monitoring biological processes within AS WWTP. The analysis revealed anninterdependent link between EPS production, sludge settling characteristics and mode of reactornoperation. An inverse relationship between F/M ratios and EPS quantities was seen but a positivenlink between EPS levels and aggregation indices, a measure of the efficiency of inter cellnattachment and which indicates good settling properties, was also seen. This indicates thatnduring high F/M conditions in lab-scale AS reactors, low levels of EPS may be produced whichncould have a negative impact on settling of the biomass. Floc architecture was examinednunder the microscope. Transient growth of filamentous bacteria was seen in the reactors.