The Experimental Study Of Urban Wastewater Advanced Treatment By MBBR Method A~2/O Integrated Process

Yellow River Basin is one of the most serious for the shortage of water resources inChina. Because of pollution and serious waste of Lanzhou section of Yellow River, it isextremely urgent to seek cost-effective water-saving is imminent. According to the actualinspection, it is known that the effluent of sewage treatment plant in Lanzhou is oftendischarged directly into the Yellow River. To some extent, it not only makes the Yellow Riverwater to be contaminated again, but also causes a serious waste of water resources. Waterquality and stability of wastewater from Sewage treatment plant effluent is the mosteconomical and environmentally friendly way for treatment reclamation and reusing.Considering the character of high ammonia nitrogen and total nitrogen, low organiccarbon from a sewage treatment plant secondary effluent in Lanzhou, of which advancedtreatment study through MBBR method A²/O and micro-flocculation filtration/slowbiofiltration. Through different fillers on the indicators removal effect and different fillersbiomass,biological activity determination to choice economic applicable MBBR methodfiller;The reactor is launched by combining aerobic precoating and organic load descendingmethod after that, the evolution process of microorganism through the removal of ammonianitrogen and COD in this project and we have a Nitrogen analysis.The effect of differentcoagulant and dosage on coagulation effect was studied to choose the best mixed coagulant,contrast analysis the removal effect of each index, the technical characteristics ofMicro-flocculation filtration and slow biofiltration.The results show that:（1） Filler contrast reactor started by the method of combination of pre-start decreasinghanging aerobic membrane in advance and with decreasing organic loading method,. where1#（filler is a multi-faceted hollow ball）,2#（high density microbial-modified polyurethanecationic sponge）reactor hangs biofilm successfully in about30days when successful biofilm,while removal efficiency of3#（modified biological suspended filler WD-F10-4）reactor in40days is still not stable in40days. For ammonia, the removal rate of COD1#reactor couldremovereach80%NH3-N, and40%COD, the removal rate of2#and3#reached could reach90%,30%,%respectively and55%for3#,18%, respectively. It is shown that1#,2#reactor,the COD removal rate of NH3-N and COD ammonia nitrogen was obviously higher than thatof3#. The biomass and bioactivity in different packing reactor were determined, which isknown that the biomass in1#and2#is equal （3.1×10⁹and2.7×10⁹E·coli respectively）, whilethat of3#（1.5×10⁹个E·coli）is half less than1#and2#. the rate of oxygen consumption ofmicro-organisms packed in2#reactor is faster than1#,3#reactor. The microbial activity isbetter in2#reactor. In view of the2#sponge stick together easily in the process of packing instreams, fillers in2#can be installed in the1#hollow, forming a new combined packing. Atthe same time.view of the2#sponge packing in the fluidization process easy to stick together, 2#can be packed in1#polyhedral hollow ball, form a kind of new-style combined filler.（2） MBBR method A²/O process is started using by combination of pre-hunging theaerobic membrane and the descending organic load descending combination. The reactor hasgone through three stages: the microbial adaptation phase, microbial activity improvementstage and stable stage of microbial activity. In the condition that tank low-carbon anddegradation-resistant effluent from secondary sedimentation of municipal wastewatertreatment plant was used as raw water, refractory treatment was successfully started after50days. When influent ammoniathe concentration of NH3-N,COD in influent ranged from was10to20,30to70mg/L, the ammonia nitrogen removal average rate reached85%,37%,inwhich the average concentration is1.6,24.9mg/L. When the turbidity of influent is1⁶NTUthe value of effluent turbidity was4.18⁷.64NTU,the effluent turbidity higher than enterwater;.Removal average rate of NO₂-N,NO₃-N,TN were68.9%,58.1%and69.9%.（3） The results according to the different coagulant and dosage of static experimentshows:PAC can removal COD and turbidity better the PAFC and FeCl3. The best dosage ofPAC is5mg/L. After Micro-flocculation filter NH3-N,COD,turbidity and TP can be remove15%、37%、83%and68.15%respectively, The average concentration of NH3-N、CODturbidity and TP in effluent are1.5mg/L、14.70mg/L、0.83NTU and0.17mg/L respectively.（4） NH3-N,COD,turbidity and TP can be removed85%、47%、80%and9%in Bio-slowsand filtration, the average concentration of NH3-N,COD and TP in effluent are0.25,11.58,0.42mg/L, turbidity is less than1NTU.Compared to the removal of the indicatorsand the technical and economic analysis between micro-flocculation filtration and biologicalslow sand filtration device, it can be concluded that these two processes have their ownadvantages and disadvantages. According to the actual situation and the target water qualityrequirements, we can select the appropriate process.Secondary effluent from wastewater treatment plant was treated through MBBR methodA²/O-Pretreatment in this experiment.The treatment could effectively remove ammonia andtotal nitrogen, while organic matter was broken down. That micro-flocculation filtration isadded after the pre-treatment process was compared with biological slow sand filtration.Besides, effluent water quality would be further improved and more stable, so as to reachhigh-quality standard of reclaimed water quality.It can make the double contradiction of theLanzhou section of the Yellow River water pollution and water shortages ease. Energyconservation provides good environmental and social benefits.