Enhanced Treatment Of Disperse Dye-production Wastewater By Self-assembled Organobentonite In A One-step Process With PAC

Disperse dye-production wastewater have the nature of heavy color, serious toxicity, and low biodegradability. Combinations of physicochemical pre-treatments and biological systems have appeared as common and conventional options for the wastewater. One-step process of organobentonite has the advantages of simple operation, high decoloration efficiency and effective improvement on the biodegradability of wastewater, which is suitable for the pre-treatment of highly concentrated refractory organic wastewaters. In this thesis, the combined one-step process with PAC coagulation was performed as a two-step treatment whereby sorption was followed by coagulation. The removal efficiency of the one-step process for toxic organic pollutants and its effect on the biodegradability of wastewater were investigated. The effects of PAC on the precipitating and dewatering performance of sorbed organobentonite were evaluated, which might provide technical support for the control of dye industrial wastewater. The main findings of this thesis are summarized below:(1) PAC coagulation could enhance the removal of toxic organic pollutants by oeganobentonite and thus improve the biodegradability of wastewater. When the the dose of CTMAB, bentonite and PAC was 60% CEC, 0.5 g/L and 0.5 g/L, respectively, the removal rate was 64.4% for anlines and 76.9% for nitrobenzenes, which was 22.2% and 33.4% higher than the one-step process. And the BOD5/CODCr of treated effluents was increased by 0.165.(2) The precipitating performance of sorbed organobentonite was obviously improved by PAC coagulation, and thus achieved a rapid separation by settlement. PAC could break the stability of organobentonite suspension by charge neutralization. Meanwhile,oeganobentonite could act as coagulation crystal nucleus, which would accelerate the solid-liquid separation by one order of magnitude and shorten the precipitating time by two-third. With PAC coagulation, the water content of sludge decreased from 98.1% to 97.4%,and the sludge volume reduced by 26.3%, which was beneficial to the reclamation and utilization of organobentonite.