Study On Effect Of Extracellular Polymer Substances On Adsorption-regeneration And Bio-flocculation Of Activated Sludge

Effect of extracellular polymer substances in activated sludge on adsorption-regeneration and bio-flocculation was studied in this paper. The main conclusions wereas follows:1) The effect of EPS on adsorption and regeneration of activated sludge was studied.The experiment results indicated: EPS were remarkably correlative with adsorptivecapacity, and with loading rate Ns reducing, EPS increased, so did adsorptive capacity ofsludge; the organics variety affected markedly adsorptive capacity of sludge, andadsorption mechanism was bio-flocculation function. Besides, regeneration processcould increase sludge adsorptive capacity in middle loading rate (Ns=0.3~0.5kgBOD5/kgMLSS.d), and could not do that in high loading rate (Ns=3.0~5.0kgBOD5/kgMLSS.d). The cause was that regeneration process could compelsludge in middle loading rate (Ns=0.3~0.5kgBOD5/kgMLSS.d) to enter intoendogenesis metabolizability phase, which induced flocculation substances EPS toincrease, and so flocculation activity of sludge increased and absorption capabilityimproved. But regeneration process could not change EPS content of sludge in highloading rate (Ns =3.0~5.0kgBOD5/kgMLSS.d). At one time, the regeneration processmade dehydrogenase and OUR of activated sludge reduce, which resulted inmetabolizability activity reducing. The regeneration of high loading rate sludge wasinvalid.2) The quantitative effect of EPS, Ca2+ and pH on bio-flocculation was studied bymeans of simulating the forming of bio-flocs. The experiment results indicated: WhenpH was more than7.5, concentration of EPS and Ca2+ was respectively more than 70mg/L and 300 mg/L, flocs could form easily. At the same time, the regression equationwas deduced in orthogonal experiment of EPS Ca2+, and pH: ηtuide=-901.70+97.35pH+1.96Ca2++9.08EPS-0.11pH·Ca2+ -0.91pH·EPS-0.02Ca2+·EPS+0.0021pH·Ca2+·EPS Regression analysis showed: pH was the first remarkable factor, EPS was secondand Ca2+ was third.3) These factors including loading rate Ns, dissolved oxygen DO, watewatertemperature, concentration of Ca2+, pH and Wastewater quality which affected EPSwere studied by means of parallel experiments. The experiment results indicatedThe III英文摘要effect of loading rate Ns on EPS was highly remarkable, DO was commonly remarkableand watewater temperature was not remarkale; the influence mode was concluded: EPS=26.44-2.80Ns+1.26DO and EPS=22.25-2.18Ns+0.20T; with concentration of Ca2+increasing, EPS, dehydrogenase and OUR increased, which resulted in the increase ofactivity of flocculation and metabolizability. pH affected EPS remarkably, and when PHwas 7~8, sludge had good flocculation and metabolizability activity. Wastewater qualityaffected the content and component of EPS, dehydrogenase and OUR remarkably,which made sludge flocculate and metabolize differently.4) The organics removal kinetics of bio-flocculation was studied by means of therelation between EPS and bio-flocculation. The mode of organics removal kinetics andkinetics constant in A-step of AB process were deduced.The study on mechanisms of adsorption-regeneration and bio-flocculation willbenefit to develop low power-wasting and high efficient bioreactor.