Treatment Of Rural Domestic Sewage By Micro-aerobic Hydrolysis/SBBR Processes

In recent years,with the rapid improvement of the living standard of rural residents in China,the discharge of rural sewage is also increasing.Most villages lack a complete sewage collection and sewage treatment system,and the random discharge of domestic sewage has caused serious pollution to the ecological environment of rural areas,which not only seriously threatens the safety of groundwater quality,but also causes the eutrophication of nitrogen and phosphorus in lakes,and may even lead to the production of black and smelly water bodies.Accordingly,strengthen rural life sewage to treat appear extremely urgent.Although there are many researches on rural domestic sewage treatment at present,most of them have problems such as large infrastructure investment,high operation and management cost and low treatment efficiency,which result in the idling of many rural sewage treatment facilities.Therefore,it is necessary to combine the actual situation of rural areas to develop a set of sewage treatment technology suitable for the actual situation of rural areas with high efficiency,low investment cost and convenient management.Taking rural domestic sewage as the research object,this paper studied the effect of micro-oxygen hydrolysis and acidification/aerobic SBBR combined process on the removal of pollutants in rural domestic sewage and the optimization of process parameters.Firstly,the effects of hydraulic residence time,aeration quantity and temperature on the pretreatment of rural domestic sewage by micro-oxygen hydrolysis and acidification were investigated,and the optimal operating parameters of micro-oxygen hydrolysis and acidification process were determined.Secondly,the effect of microbial immobilization carrier,hydraulic residence time,dissolved oxygen and temperature on the deconsolidation effect of aerobic SBBR process was studied,and the optimal operating parameters of aerobic SBBR process were determined.Finally,the study on the stable operation of the combined process was carried out to investigate the removal effect of COD,NH3-N,TN and TP in rural domestic sewage during the stable operation of the combined process,and the removal rate of pollutants in each reaction stage was analyzed.At the same time,a comparative study was carried out on the treatment of rural domestic sewage by combined process and aerobic SBBR process alone.The main conclusions are as follows:?1?The optimal hydraulic retention time of anaerobic hydrolysis and acidification is 1d,at which time the average removal rate of COD can reach 66.3%,NH3-N and TP can not be removed,TN can be removed weakly,and SS can be removed well.The effluent biodegradability is greatly improved,and B/C value can increase from 0.46 to 0.64.?2?Anaerobic hydrolysis acidification can strengthen hydrolysis acidification on pollutants removal,anaerobic hydrolysis acidification of the best air is 0.2 L/h,the system of COD and NH₃-N,the removal rate of TN,TP and SS were 72.53%,33.67,37.58%,11.63%and 74.32%,and the corresponding water COD and NH₃-N,TN,TP and SS average concentration of 256.86 mg/L,32.34 mg/L,45.68 mg/L,4.56 mg/L and 156.38 mg/L,respectively.The average effluent concentrations of COD,NH₃-N,TN,TP and SS were70.56mg/L,21.45mg/L,28.52mg/L,4.03mg/L and 35.27mg/L,respectively.In addition,the removal of NH₃-N,TN and TP by the system increases with the increase of aeration capacity;the effluent of COD by the system increases first and then decreases with the increase of aeration capacity;the removal of SS by the system decreases with the increase of aeration capacity and finally tends to be stable.?3?The optimal temperature of micro-oxygen hydrolysis and acidification was 25?,and the average removal rates of COD,NH₃-N,TN and TP in the system were 68.97%,33.37%,33.37%and 33.37%,respectively.?4?Aerobic SBBR with"sponge iron+polyurethane foam"as filler has better removal effect on pollutants than that with"polyurethane foam"as filler;System for COD and NH₃-N and TP removal rate increases with the increase of HRT,but system of TN removal rate after the first increases with the increase of HRT decreases,and the system best HRT for 4 h,the system of COD and NH₃-N,the average removal rate of TN and TP were 46.15%,92.90%,50.57%and 92.11%respectively,the water concentration have reached the GB18918-2002"urban sewage treatment plant pollutant discharge standard"in the level of A standard.?5?The optimal dissolved oxygen concentration of aerobic SBBR process is 2⁴mg/L,and the removal rate of COD and NH3-N by the system increases with the increase of dissolved oxygen concentration,but the removal rate of TN and TP by the system increases first and then decreases with the increase of dissolved oxygen concentration.The removal of COD,NH3-N,TN and TP by the system increases with the rise of temperature,while the removal of nh3-n and TP by the system increases first and then decreases with the rise of temperature.?6?When rural domestic sewage is treated by aerobic SBBR alone,when the hydraulic residence time of the aerobic SBBR reactor is 12h,the effluent of the system can reach the standard of grade A?GB18918-2002?;When the combined process is in stable operation,the system has a good deconditioning effect on rural domestic sewage.At this time,the operating parameters of the combined process are:HRT of micro-oxygen hydrolysis and acidification is1d,aeration of micro-oxygen hydrolysis and acidification is 0.2 L/h,HRT of aerobic SBBR process is 4h,dissolved oxygen is 2-4 mg/L,and the temperature is 25?.In addition,compared with the separate aerobic SBBR process,the combined process can save 8 hours of aeration time and greatly save the operation power consumption.