Study On Biological Technology For Simultaneous Removal Of Carbon And Nitrogen From ABS Resin Wastewater

ABS resin is the copolymerization of acrylonitrile, butadiene and styrene, is one of fivegenerally used resin.ABS resin has good heat resistance, easy processing, corrosion resistance,good electrical properties and molding surface, and it has a high toughness, poor temperatureperformance,at the same time it retains the salient features of polyacrylonitrile (PAN),polystyrene and poly-butadiene (PB). It is widely used in Automobiles, family appliances,communication accessories, daily necessities etc. industries. In recent years, ABS resin indomestic demand showed a rapid growth trend, China has become one of the world’s largestproducing and consuming countries of ABS resin, while domestic ABS resin productionplants cannot meet the strong market demand. Driven by the strong market demand, theproduction of ABS resin continues to increase, ABS resin wastewater treatment problemshave become increasingly prominent.ABS resin wastewater has a high organic content, it also contains a lot of organic nitrilesand aromatic toxic compounds, and which is mixed with latex or latex resin powder and othersolid material, it is one kind of typically high organic nitrogen toxic organic industrialwastewater. At present, the widely used ABS resin wastewater treatment technology isflotation-biological treatment processes: wastewater comes from the flotation to removelatex and powder, to ensure stable operation of the subsequent biological treatment systems;then it goes through biological methods, to remove the pollutants dissolved in the wastewater.The biological treatmentof ABS resin wastewater has problems of too many processing unitsand has a long HRT. As the organic matter in ABS resin wastewater can be mostly degradedby activated sludge which is domesticated, it has feasibility to use biochemical process to thetreatment of ABS resin wastewater. Therefore, it is intended for ABS resin wastewatercharacteristics, to find a simple process, stable biological treatment techniques and to studythe effects of various process conditions and process optimization.It studies ABS resin wastewater after the treatment of coagulation and flotation. Afterstudying the variation of the composition of the wastewater pollutants, A cycling integratedbioreactor with gas-lift and microporrus-aeration is used for the treatment of ABS resinwastewater. Upon the sludge acclimation of the reactor, it studies influent alkalinity to theremoval of organic matter and nitrogen in the wastewater, to find an efficient method ofsimultaneous removal of carbon and nitrogen from ABS resin wastewater. With a gradualreduction of HRT to increase the processing load of the reactor, It investigates the removal oforganic matter and nitrogen in the wastewater under different HRT, to get a fit HRT for thetreatment with a high loading of simultaneous removal of carbon and nitrogen from ABS resinwastewater. Mainly by controlling the amount of aeration, increasing an anoxic area, reducingcirculation flow rate in the reactor, adding carbon and other ways to strengthen the effect ofdenitrification of the reactor.It also evaluates different measures to the effects of simultaneous removal of carbon and nitrogen from ABS resin wastewater find an enhanceddenitrification technical approach. It also researches microorganisms phase and spatialdistribution of the activated sludge in the reactor with the scanning electron microscopy andfluorescence in situ hybridization methods. It investigates operating conditions of the reactorto the effect of microbial population structure, to provide the basis for further optimization ofthe reactor. It draws the following main conclusions:ABS resin wastewater after the treatment of coagulation and flotation is a typical highnitrogen organic wastewater. It uses the cycling integrated bioreactor with gas-lift andmicroporrus-aeration for the treatment of the waste water. When the hydraulic retention timeof the reactor was24h and the influent COD was800-1000mg/L，COD removal efficiencywas more than88%and organic nitrogen removal efficiency was more than99%by the singlereactor. the effluent COD was less than80mg/L,it can reach the second standard ofthe“Integrated Wastewater Discharge Standard”(GB8978-1996). GC-MS and fluorescenceexcitation-emission matrix spectrum analyses indicated that organic nitrile and aromaticorganics could be efficiently removed from the wastewater. The effluent water quality isstable, and it has strong impact resistance, the treatment process is simpler than that of thetraditional processHRT of the reactor and influent alkalinity have a significant impact on the NH3-Nremoval process. When the influent alkalinity was300-450mg/L (CaCO3), pH of the mixedliquid in the reactor remained at6.7-7.5, the HRT of the reactor is longer than24h, the DO is1~5mg/L, the effluent NH3-N is less than5mg/L. It reaches the first standard of “IntegratedWastewater Discharge Standard”.DO concentration has a decisive influence on nitrogen removal effect. Setting up aanoxic zone and reducing DO concentration in the oxic zone can significantly enhancedenitrification in the reactor and improve TN removal efficiency. When the DO in the reactoris controlled better (DO in oxic area is0.4-0.7mg/L, DO in anoxic area is0.06-0.2mg/L), TNremoval rate can be more than60%, significantly higher than the removal rate29%～40%when the reacter is operating in oxic conditions.SEM analysis shows that the activated sludge has closer microorganisms in the reactor.The activated sludge floc is relatively dense, It has less filamentous bacteria, andmicroorganisms and cocci bacteria has a large proportion. FISH analysis shows thatmicroorganisms in the activated sludge the is mainly bacteria, ammonia-oxidizing bacteriaand nitrite-oxidizing bacteria accounts for a higher proportion.When DO in the reactor is low,the effluent NH3-N concentration is high, but FISH analysis shows that the reactor is not lackof ammonia-oxidizing bacteria under these conditions, but DO concentration in the reactorconditions not suitable for the reaction of ammoxidation.