Ceramic Membrane Bioreactor For Advanced Treatement Of Rural Domestic Sewage

China embraces more than 600 million rural residents.Due to the backward economy in rural areas and the lack of appropriate sewage treatment equipment,huge amounts of rural domestic sewage in high nitrogen and phosphorus concentration are discharged directly into natural water body without necessary treatment,resulting in extensive water contamination.In this study,ceramic membrane bioreactor was used to treat rural domestic sewage,and its efficiency of contamination removal was investigated.Experiments were firstly conducted under regular running condition to see the system's pollutant removal capabilities.Secondly,the parameters of running condition were optimized in order to improve the quality of outflow.Then,in order to intensify the nitrogen and phosphorus removal efficiency,other parameters were further optimized.This study can provide a useful reference for the rural sewage treatment.The study shows that:1)During the regular operation:1.While the concentrations of inflow were??chemical oxygen demand COD?=461.00⁵61.00 mg/L,??total nitrogen TN?=33.97⁵4.00mg/L,??ammonium nitrogen NH₄⁺-N?=18.70-29.67 mg/L,??total phosphorus TP?=4.78-5.77 mg/L,the removal rates of COD,TN,NH₄⁺-N and TP were 86.87%,47.64%,95.00%and 12.32%,respectively,and the outflow concentrations were 67.48,22.59,1.13 and 4.57 mg/L,respectively.The interception effects of ceramic membrane on COD,TN,NH₄⁺-N and TP were 79.94%,18.92%,6.20%and 2.80%,respectively.In order to improve the quality of outflow,it is necessary to optimize the important parameters of ceramic membrane bioreactor.2.The concentration of total E.coli in the inflow was8.70×10⁵¹.50×10⁶ MPN/100mL.Under the UV dose of 35 mJ/cm²,the average concentration of E.coli in the outflow didn't exceed 35MPN/100mL,which met the 1A discharge standard?1000 MPN/L?.3.12 minutes of suction filtration and 3 minutes of back washing could delay the fouling of ceramic membrane.Using sodium hypochlorite solution at the concentration of 1000 mg/L could effectively remove the pollutants adhering to the membrane and restore the initial membrane flux.2)In order to improve the pollutants removal efficiency,operation parameters were optimized:1.While the membrane pore size was 50 nm and membrane flux was20 L/?m²·h?,the interception rate of organic pollutants by ceramic membrane reached 92.86%.It also had the best performance in delaying membrane fouling and the cleaning cycle of membrane could be 37 days.2.When the sludge load was 0.35-0.60 kg COD/?kg sludge·d?,the removal rates of COD and NH₄⁺-N reached 95.33%and 95.15%,respectively,and the average outflow concentrations were 24.01 and 1.87mg/L,which met the 1A discharge standard.However,the removal efficiency of TN and TP was rather low.Therefore,the reinforcement of nitrogen and phosphorus removal is needed.3)In order to intensify the nitrogen and phosphorus removal efficiency,other parameters were optimized:1.While the process reflux ratio was 200%,the dissolved oxygen?DO?was 2.00 mg/L,the hydraulic retention time?HRT?of anaerobic pond was3.00 h and the HRT of anaerobic pond was 2.00 h,the system reached the best removal efficiency.The average removal rate of TN was 69.64%,and the average concentration of TN of outflow was 11.73 mg/L,which met the1A discharge standard.Meanwhile,the water quality of outflow was stable with less energy consumption.2.The phosphorus removal efficiency of ceramic membrane bioreactor could be effectively improved by using carrier absorption.Under the optimum hydraulic loading of 1.40 m³/?m³·d?,the TP average removal rate reached 93.17%,and the TP concentration of outflow was 0.31 mg/L,which met the 1A discharge standard.It was simpler and cheaper to maintain compared with chemical phosphorus removal methods.Ceramic membrane bioreactor is one of the new water treatment processes and has great application potential in rural domestic sewage treatment.This study constructed a complete treatment process of ceramic membrane bioreactor for rural domestic sewage.It provides an important reference for rural domestic sewage treatment.