The Experimental Study On Domestic Wastewater Treatment By Bioflocculation

In activated sludge process, the removal of organic pollutants mostly depended on solid/liquid separation, to which bioflocculation is critical. Good bioflocculation contributed to improve settling and dewatering properties of activated sludge. With wastewater being treated by bioflocculation, not only good effluent quality was obtained, but also subsequent sludge disposal costs were reduced. So biofloccucation caused extensive attention. The research of bioflocculation on wastewater treatment was investigated by micro-scale, semi-full-scale and bench experiments.The study results showed that the sludge of bioflocculation matured in a week by simultaneous cultivation and domestication. Then good flocculation was obtained. And the optimum parameters were that aeration flux, recycle ratio, aeration time, flocculating time and SRT were 100L/h, 30%, 2h, 30min, 6d, respectively.Good bioflocculation was obtained after three weeks' steady operation of semi-full-scale experiment. The removal efficiency of COD, SCOD, NH3-N, PO43--P were about 70%, 40%, 15% and 45% respectively.Adsorptive kinetics and equilibrium models were investigated by experiment of both aerobic and anaerobic sludge adsorption. The results showed that sludge concentration and influent COD were in positive proportion to adsorptive capability of both aerobic and anaerobic sludge. But temperature was in inverse proportion to adsorptive capability of both aerobic and anaerobic sludge. Adsorptive equilibrium was reached within 15 min. Under the same experimental condition, adsorptive capability of aerobic sludge was greater than that of anaerobic sludge. Although the adsorption of both aerobic and anaerobic sludge was governed by intraparticle diffusion process, it was not main rate determining step through the adsorption. Both anaerobic and aerobic sludge adsorption process followed the pseudo second order model rather than the first order model or the second order model. The equilibrium data fitted well to both the Freundlich and Langmuir adsorption models.