A Pilot Scale Study On Biological Contact Oxydation-Biological Aerated Filter Combined Process In Synthetic Detergent Wastewater Treatment

Industrial wastewater is a main pollution source of the environment pollution. It ishigh COD and high LAS concentration in synthetic detergent industry wastewater. Itcan cause severe environmental damage when was discharged without treatment.Therefore, it is necessary to develop a high efficient, economical process in syntheticdetergent industry wastewater treatment.Through comprehensive analysis,"biological contact oxidation-biological aeratedfilter" combined process was adopted in synthetic detergent industry wastewatertreatment, when the wastewater was pretreated by coagulation sedimentation andhydrolytic acidification. Base on engineering application, the treatment efficiencies ofboth combined carrier and MBBR carrier were compared. And also, the treatmenteffect of "biological contact oxidation-biological aerated filter" combined processwas regarded.Under similar operation condition, the biofilm formation and start up time ofcombined carrier reactor was13days, while MBBR carrier’s was25days. Whenbiofilm formed well, plenty of protozoa and metazoan was observed on both kinds ofcarriers, which indicates a good bio-phase.the biological phase of the biofilm on both kind of the carriers were good, plenty ofprotozoa and metazoan was observed.In continuous operation, the COD and LAS removal rate and removal efficiency ofboth combined carrier reactor and MBBR carrier reactor was examed. Combinedcarrier reactor performed the83.5%best COD removal rate when DO of the mixedliquid is4.0mg/L, while MBBR carrier reactor performed the85.1%best CODremoval rate when the DO of mixed liquid is3.0mg/L. In organic load respect,combined carrier reactor can maintain a83%or above COD removal rate when wentthrough0.80-1.50kg COD/m3.d organic load; MBBR carrier reactor can maintain a82%or above COD removal rate when goes through1.00-2.25kg COD/m3.d organic load. In terms of LAS removal, combined carrier perform the best LAS removal effectwhen DO=3mg/L, while MBBR’s DO=2mg/L, the removal rate of the2carriers is88.5%and89.5%.In the sludge concentration respect, the MLSS and MLVSS of combined carrierreactor is6.9g/L and3.1g/L, the MLSS and MLVSS of MBBR carrier reactor is6.6g/L and3.9g/L. In terms of mixed liquid sludge settling performance, the SVI ofcombined carrier reactor and MBBR carrier reactor are255and133.As the result of carrier comparison, it takes longer for MBBR carrier to get biofilmformed. When compared to combined carrier, MBBR carrier performs better insynthetic detergent industry wastewater treatment, it can maintain a good COD, LASremoval effect in lower DO, and bear higher organic load. What’s more, MBBRcarrier carries more organic sludge, which has better settling characteristic.Combined process treatment effect was examed, MBBR carrier is adopted inbiological contact oxidation, ceramisite filter media is adopted in biological aeratedfilter. Optimal HRT is obtained by experiment: biological contact oxidation20h,biological aerated filter1.2h. When operated in optimal HRT, COD and LAS removalrates of combined process are89.6%and96.3%. Through continuous operation,combined process perform a organic load stage split phenomenon, excellent organicshock load resistance and pollutants removal effect is performed.