Design And Pilot-Scale Study Of A/MBBR Treatment Process For Domestic Sewage In A Scenic Spot In Shaanxi Province

Based on the investigation of the water quality situation domestic sewage from Tianliushan scenic spot in Shaanxi Province,the treatment process,the process flow and the dimensions of each structure were designed,and an integrated domestic sewage treatment equipment was built.The operation performance of this process was determined in this paper.The effluent met the first-class B standard of GB18918-2002,and finally could be reused for forest irrigation.The main contents and conclusions are as follows:(1)A/MBBR(AO+MBBR)process was selected as the core process,and a new type of high-efficiency suspended carrier PPC was selected for the MBBR.The treated water volume was set to be 30 m3/d,on which basis,the structure and additional equipment in A/MBBR process were designed and calculated.The CAD drawings were drawn according to the design dimensions,and the equipment was built.(2)The A/MBBR process was started up,and the average effluent concentration of each index reached and stabilized at low concentration in the later stage of start-up.The removal rates of COD,BOD5,NH3-N,TN,TP and SS were 80%,92%,75%,55%,80%and85%,respectively.After start-up,the equipment debugging was carried out,and the reflux ratio and DO single factor experiment were carried out.The optimum operating parameters were determined as DO=2.0 mg/L-2.5 mg/L,and the reflux ratio was 130%.The average removal rates of COD,BOD5,NH3-N,TN,TP and SS were 81%,93%,72%,52%,78%and88%,respectively.(3)After stable operation of A/MBBR process for 34 days,the average effluent concentrations of COD,BOD5,NH3-N,TN,TP and SS were 41 mg/L,8 mg/L,7 mg/L,16mg/L,0.4 mg/L and 9 mg/L respectively,and the average removal rates were 83%,93%,79%,53%,81% and 83% respectively.(4)According to the observation by biological microscopy,the microbial population of PPC filler was abundant after operation,and the Vorticella,Rotifer,Colepidae,Epistylis and Aspidisca etc.were observed.According to SEM analysis,the internal pore of PPC carriers before operation were well developed,the pores were numerous and dense.The structure of large pore woven reticulate wall became blurred after operation,and the microorganisms and organic matters were observed to be attached onto the wall.ThroughSEM-EDS analysis,the amount of C,O and N elements decreased and the specific gravity of PPC filler decreased after operation,indicating that the anaerobic and aerobic reactions took place simultaneouslyin the carriers.There are 70 figures,10 tables and 84 references.