Study On Treatment Of The High Concentrated Cattle Wastewater By Membrane Technologies

Because of the increasing discharge of manure from livestock and poultry farming annually,livestock and poultry waste has become the third major source of pollution in China,after industrial pollution and domestic pollution.And it also become a major problem in rural environmental management.These untreated wastewater causes serious environmental pollution and threatens human health.It's necessary to have an efficient treatment for livestock and poultry aquaculture wastewater.This study explored the optimal operating conditions of membrane system?chemical flocculation-ultrafiltration-reverse osmosis?for the cattle wastewater treatment.And the main contents and conclusions are as follows:Chemical flocculation pretreatment:It focused on the high concentration of cattle wastewater.Polyaluminium Chloride?PAC?and Polymeric Ferric Sulfate?PFS?were selected as flocculants,and Polyacrylamide?PAM?was selected as coagulant aid.This study observed the effect of flocculation on the cattle wastewater with different types and dosages of flocculants and coagulant aid,different mixing speeds and mixing times.Finally,it determined that the optimal conditions were:1.2%PFS was added into the high concentration of cattle wastewater,300 r/min rapid mixing for 30s,150 r/min medium speed mixing for 5 min,then 40 mg/L CPAM with molecular weight of 12 million was added,150 r/min mixing for 30 s,50 r/min mixing for 5 min,finally the sample was standed for 1 h.Following by centrifugation and sieving,the turbidity of the effluent was 3.62 NTU and COD was 285 mg/L.The removal rate of the turbidity and COD were 99.92%and 94.51%,respectively.The effect of this method using both PFS as flocculant and CPAM as coagulant aid for pretreatment of cattle wastewater was significant.It provided the beneficial conditions for the subsequent membrane process.Therefore,this method was used to pretreat the high concentration cattle wastewater.Ultrafiltration:This work studied the performance of multichannel ceramic membranes for cattle wastewater treatment at different operating conditions:membrane pore size,transmembrane pressure?TMP?,cross-flow velocity?CFV?,operating temperature and pH of feed.According the results,the optimal operating conditions were:membrane with pore size of 50 nm,TMP of 0.2 MPa,CFV of 4 m/s,operating temperature of 40?and pH 6.Under these conditions,the concentration experiments for cattle wastewater treatment were investigated.Results showed that this membrane could operate up to a concentration factor of 5 with high removal rate of suspended solid?SS?,turbidity,and total phosphorous?TP?,which were 100%,99.20%and 80.21%,respectively.In addition,the performance of membrane also kept a stable state in 5 independent cycles.These findings provided an efficient ceramic membrane treatment for cattle wastewater.Reverse osmosis:This work studied the performance of reverse osmosis membranes in the first stage for cattle wastewater treatment at different operating conditions:transmembrane pressure,influent flow rate,operating temperature and feed pH.According to the results,the optimal operating conditions were:operating pressure of 0.8 MPa,flow rate of 200 L/h,operating temperature of 35?and feed pH 6.Under these conditions,the concentration experiments for cattle wastewater treatment were investigated.Results showed that the effluent kept a good quality until the volume of permeate was 20%of the influent volume.Next,the effluent of the first-stage reverse osmosis was subjected to advanced treatment of secondary reverse osmosis under the optimal conditions as above.The results showed that the concentration of the substance in the permeate increased as the increasing volume of permeate.But all of them could meet the secondary standard in“Discharge standard of pollutants for municipal wastewater treatment plant”.This work based on physical and chemical method,and designed the method of“ultrafiltration and reverse osmosis”for the cattle wastewater treatment.The removal rate of EC,NH₃-N,TN,COD,SS,turbidity and TP could reach 87.49%,98.88%,98.90%,100%,100%and 99.96%,respectively.It not only solved the problem of environmental pollution of cattle wastewater,but also overcome the shortcoming of traditional treatment,such as large area and enviornmental factors.This study provided new ideas and laid research foundation for treatment of livestock and poultry wastewater,as well as gave theoretical guidance for its practical application.