Stduy On Application Of Magnetic Separation And Biological Coupling In Wastewater Treatment

In view of the high concentration of pollutants in piggery sewage,this paper proposes magnetic separation and biological coupling technology to treat piggery sewage.This technology has realized the complementary between the magnetic separation technology and the microbial degradation method,and has the advantages of good treatment effect,short operation cycle,small footprint and low cost.The relevant research results can provide certain technical reference for the treatment of piggery sewage.In this paper,piggery sewage was used as the experimental water sample,which was first treated by magnetic separation system,and the removal rates of turbidity,chemical oxygen demand(COD)and total phosphorus(TP)were taken as indicators.Firstly,through the single factor experiment,the optimal parameters of each main factor are obtained.When the p H value is 7.0±0.3,the dosage of polyaluminum chloride(PAC,4% mass percentage concentration)is 15.0±1.0ml/L,the dosage of polyacrylamide(PAM,0.2% mass percentage concentration)is 40.0±1.0ml/L,the dosage of magnetic seed is 300.0±1.0mg/L,and the settling time is 20±1.0min,these are the optimal conditions obtained by single factor experiment.Then the interaction among the main factors was analyzed and studied by using design-expert software and response surface method.According to the response surface analysis,the optimal process conditions for turbidity,COD and TP removal were obtained.In order to facilitate the actual operation,the parameters were adjusted as follows: 15.5ml/L for PAC,6.8 for p H,300mg/L for magnetic species,and 39.5ml/L for PAM.Under this condition,the removal rate of turbidity was 79.53±0.10%.The removal rate of COD was 58.50±0.2%.The removal rate of TP was 90.90±0.18%.At the same time,the velocity of magnetic flocs settling in the magnetic field was 450±0.2cm/min,and the volume of the generated magnetic flocs was only 0.8±0.1ml.From different environments,a strain LZ77 capable of highly efficient COD degradation was isolated and screened,which was identified as Bacillus sp.Through testing,the screened strain LZ77 had the highest removal rates of COD and Suspended Solids(SS)of 80.90% and 82.00%.The removal rates of ammonia nitrogen and total nitrogen(TN)of Zhi77 strain reached 96.08% and 94.5% respectively.Then,the heterotrophic nitrifying bacteria Zhi77 and LZ77 that have been screened out in the laboratory will work together to treat the treated sewage after magnetic separation.Through the detection of magnetic separation and biological coupling technology treated piggery sewage,the removal rate of turbidity in the effluent was 79.53%;the removal rate of COD is 95.05%;the removal rate of ammonia nitrogen was 96.08%;the removal rate of TN was 94.5%;the removal rate of TP was 93.28%;the removal rate of SS was 82.7%.Therefore,magnetic separation and biological coupling technology can effectively treat piggery sewage.