Research On The Removal Of Bactericidal Components In Wastewater Pretreatment For Latex Paint Production By Flocculation Precipitation And Electrocoagulation

Latex paint wastewater contains chemical substances such as emulsion,emulsifier,auxiliaries,pigments and fillers,and also contains fungicides and fungicides.The existence of fungicides makes the latex paint wastewater with poor biochemical property more unfavorable for subsequent biodegradation.At present,the main treatment methods of emulsion paint production wastewater are the combination of coagulation sedimentation,adsorption and biochemical methods,but the simple coagulation sedimentation and adsorption methods are not ideal for the removal of mold and bactericide in the wastewater,which are not conducive to the subsequent biochemical treatment to varying degrees.Scheme 1: three different flocculants,PAC,PAS and PFS,were used to flocculate and precipitate the simulated emulsion paint wastewater.According to the order of adjusting parameters: flocculant dosage → p H value → coagulant aid PAM dosage,the effects of different conditions on wastewater treatment were observed.Then,COD and organic antimicrobial content(MIT,CMIT,bit,etc.)of the supernatant were measured.According to the results,the above parameters,treatment temperature and the dosage of reducing agent were adjusted twice,the results showed that the content of total fungicides decreased from 33.68 mg/L to 9.18 mg/L with PAC as flocculant and 85.61% as PAS,34.64 mg/L to 9.53 mg/L,with a total reduction rate of 85.06%.When PFS was used as flocculant,the content of total fungicides decreased from 36.39 mg/L to 9.96 mg/L,with a total reduction rate of 84.38%.Scheme 2: the simulated emulsion paint production wastewater is treated by electric flocculation.The parameters such as the appropriate concentration volume ratio → current density → plate spacing → reaction time are measured by experiments in the self-made electric flocculation experimental device.The content of organic bactericide is detected by changing the temperature of the reaction tank and at the same step in the reaction process,and the effect on the removal rate of COD and bactericide is observed The optimal experimental parameters are obtained.The COD reduction rate increased from 87.70% to 89.33%,the turbidity reduction rate increased from 96.58 to 96.63,and the reduction rate of target isothiazolinone fungicides was increased from 69.18% to 92.10%.