Study On Characteristics Of Super Shallow Airfloatation+A/O Technique+Flocculation And Sedimentation Tank+Biological Aerated Filter(BAF) To Deal With Methanol Wastewater

In this paper, it took methanol production wastewater of Xinxiang Zhongxin Chemical company as study object, to remove COD> SS and ammonia respectively away from the wastewater under the assistance of "Super shallow airfloatation+A/O technique+Flocculation and sedimentation tank+biological aerated filter(BAF)".This topic researched the choice of each processing parameters of each treatment flowsheet,studied the effect of operation、the attention operation characteristic、 correlative influencing factor、the optimal reaction conditions and treatment efficiency of each installation.The handing capacity of this project is3600m3/d,the outlet water mainly contained high ammonia nitrogen waste water、cyanide containing wastewater and domestic wastewater,firstly the former two should to be pretreated,than they were drained into adjusting tank mixed with the domestic wastewater,after that all of them uniformly got into sweage processing system.In the initial stage,the COD was about700mg/L,NH3-N was about120mg/L in the adjusting tank,by means of the sewage station’teratment and stable operation,finally the COD was below30mg/L, NH3-N was below5mg/L, simultaneously,others’quota met the discharge standards.The conclusion of the discussion could be drawn that:In the cyanide breaking system, water-permeability amount was106m3/h,firstly32%NaOH solution was adopted to keep pH value of10～11,secondly30%HCl solution was adopted to keep pH value of8～8.5,simultaneously10%NaCIO was additived to remove CN-.The CN-maximum density of the effluent was1.17mg/L, average was0.76mg/L, removal rate was stable and higher than95%,that was a good result.In the ammonia stripping system,firstly,32%NaOH solution was adopted to keep pH value of10～11,the average removal rate was90.94%,The NH3-N of the effluent was value of100～130mg/L, it conformed to the standards of requires of the next step.Then30%HCl solution was adopted to keep pH value of8～9, ammonia of the system had drained was absorbed by tail gas absorption tower with40%sulphuric acid solution, to avoid secondary pollution.In the super efficiency shallow air flotation,0.3%PAM solution and1.6%PAC solution were added,their rate of flow were0.5m3/h and2.7m3/h,with the best ratio、 the cheapest running costs、the best treatment effect.In the start-up phase of A/O system,with the addition of the water-permeability amount,the amount of strain in O tank had increased,the removal capacity of COD and NH3-N had also enhanced.After40days of hardening culture,the strain community had builded and matyred, the denitrification strain of A tank had builded and matyred alone with it.In the trial operation phase of A/O system,the related parameters were:in the anoxic tank the pH was6.0-8.0,the DO was0.1-0.3mg/L; in the anaerobic tank the pH was6.8-7.8,the DO was2-3mg/L;the mixed liquid reflux ratio and sludge reflux ratio were200%and100%,under this condition,the removal rate of COD and NH3-N was steady and good.The effluent concentration were58.44mg/L and21.30mg/L,their average removal rate were89.56%and84.10%.In the flocculation and sedimentation tank,0.3%PAM solution and1.6%PAC solution were added,their rate of flow were0.15m3/h and0.27m3/h,with the best ratio、the cheapest running costs、the best treatment effect.this project has4Biological Aeration Filtration,the water supply system was adopted exclusive filter cloth, blowing machine blew the single-hole film air diffusers for aeration, The water was discharged in the surrounding,the sludge was discharged by. backwashing,the designed retention time was2.1h,air purge time was4min,the combined time of air and water was6min, clean water rinse time was lOmin, backwash cycle was48h The effluent concentration of COD、NH3-N and SS were21.46mg/L、2.59mg/L and33.15mg/L,their average removal rate were18.5%、86.86%and38.53%,reached drainage standard.