Application Of Coagulation Precipitation-sand Filter-ion-exchange In Pretreatment Of Butyl Acrylate Wastewater

Major pollutants in butyl acrylate wastewater were acrylate sodium and toluenesulfonic acid sodium of high concentrations. The cost and difficult of the subsequentwastewater treatment would be dcreased. Turbidity matter and multivalent cations inthe wastewater can lead to membrane fouling of electrodialysis unit. Therefore, it isrequired to develop techniques for the removal of turbidity substances and multivalentcations. This study investigated the turbidity matter and multivalent cations removalefficiency of coagulating sedimentation, sand filtration, ion exchange and theircombination, and obtained optimized process parameters.Coagulating sedimentation can remove97%of the turbidity matter in butylacrylate wastewater. Optimized dose of coagulant and coagulant aid is poly aluminumchloride (PAC) of200-250mg/L and polyacrylamide (PAM) of15-20mg/L. Theoptimized hydraulic conditions is60L/h of feed water flow and agitator rotational speedsof500r/min,250r/min and200r/min for the three units.When pH of the wastewater increased, turbidity removal efficiency of coagulatingsedimentation and sand filtration decreased, while the multivalent cations removalefficiency increased. Sand filtration removed50%of the turbidity matter in theeffluent of the coagulating precipitation to1.0NTU, when pH of the wastewater was about5.5.When pH of the wastewater is7.5, turbidity of the effluent of coagulatingsedimentation-sand filtration was below2.0NTU, and met the requirement of the influentof following ion exchange. Removal efficiency of divalent cations by C-900resin wasinvestigated with pilot scale test. Waste water temperature increased from25℃to35℃,breakthrough volume of resin incraesed from27BV to165BV. When the operatingvelocity increased from15SV to45SV, breakthrough volume of resin decreased from226BV to95BV. Suitable conditions of ion exchange are35℃~45℃of watertemperature and operating velocity of below30SV.Combination process of coagulating sedimentation, sand filtration and ionexchange could remove the turbidity and divalent cations in the wastewater efficientlywith a stable effluent.