Study On Advanced Treatment Process Of ABS Resin Wastewater By Biological Aerated Filter

ABS resin is one of the five large-volume synthetic resins,is a very wide range of thermoplastic engineering plastics.in recent years,it has been in a wide range of production and application.The resin is composed of acrylonitrile,butadiene and styrene terpolymers,the production process will produce a typical toxic organic wastewater.Because of its high solid powder and gelatinous curd high proportion,including organic nitriles and other difficult to degrade toxic organic compounds,including high nitrogen,phosphorus organic and other characteristics,resulting in difficult to deal with waste water,complex processes and other issues.Therefore,in order to reduce the harm to the environment,China promulgated the newly-issued Synthetic Resin Industrial Pollutant Discharge Standards(GB 31572-2015).At present,a single process can not achieve the desired effect,the widespread use of coagulation flotation-biochemical combination process.The secondary treatment process can remove the latex powder and most of the dissolved pollutants in the wastewater.The effluent can reach the secondary discharge standard of GB8978-1996 "Integrated Wastewater Discharge Standard",but can not meet the industry emission standard,so it needs further processing,A set of three-stage combination process.Due to the high cost of the wastewater treatment technology and the lack of process,the BAF treatment of air blending coagulation-biochemical combined process effluent was carried out.The effects of gas and water ratio,hydraulic retention time and ferric chloride dosage on pollutant removal Effect of the effect,optimize the process parameters so that wastewater discharge standards.The main conclusions was as follows.(1)BAF for advanced treatment of ABS resin wastewater could be started successfully in 21 days using sludge discharge method with the volcanic rock as the filter materials.In order to solve the problem of low concentration of organic matter in AO biochemical effluent,the reactor was used to start the water distribution with AO effluent 1: 1 mixed with water,and the proportion of AO effluent was gradually increased.During this process,removal efficiency of suspended solids(SS)and chemical oxygen demand(COD)reached first,and then that of ammonia.(2)BAF could remove SS,COD,ammonia and total phosphorous(TP)effectively from biological treatment effluent of ABS resin wastewater.SS was removed mainly through filtration and retention effects.COD was removed mainly through filtrations,retention and biological degradation effects.Ammonia was removed mainly through biological degradation effect.TP was removed mainly through filtrations,retention and biological adsorption effects.(3)Due to rely on the reactor's own biological phosphorus removal effect,TP removal of only about 2mg / L,can not meet the water standard,Dosage of FeCl3 could facilitate TP removal by BAF.When the dosage was up to 100 mg/L,TP in BAF effluent could decreased to below 0.5mg/L.(4)Under optimized process conditions(100mg/L FeCl3,gas-water-ratio 2:1,hydraulic load 0.13m3/(m~2·h)).COD was below 50 mg/L,both ammonia and TP were below 0.5mg/L in BAF effluent,which met the newly-issued standards.(5)Along with the operation of BAF,biological mass would accumulate in BAF and periodically backwashing was required.The backwashing cycle was usually 7-8days.Gas-water combind backwashing with air 10.6 L/(m~2·s)and water 3.5 L/(m~2·s)could be used first for 2min,and then backwashing with water 3.5 L/(m~2·s)alone was followed for 8 min.The removal rate of COD and ammonia nitrogen was detected within 8 hours after backwashing.The effect of backwashing on ammonia removal rate was less than that on COD removal.After 8 h,the removal ability of pollutants could be restored to its original level.