Study On Mechanism In Rural Domestic Sewage By Biological Purification Tank

China,one of the largest agricultural countries in the world,is facing the threat of environmental and hygienic deterioration due to the fact that the domestic sewage was discharged directly,which is the consequence of the huge number of citizen crowded in the rural districts.The construction of municipal equipment appeared much lager compared with the construction of new countryside.It was often seen that the untreated sewage were discharged into the nearby river directly.The environmental awareness was thin and lacked among peasants.The applications of treatment technologies of rural sewage in Shanghai suburb not only have poor performance for the lack of effective management mechanism.Above these the main reasons which lead to the river pollution in Shanghai suburb.According to this subject,the new craftworks "BPT-EEFR" was studied by DongHua University which are supported by shanghai science committee,combining foreign advanced technical.This system has a good effect which is piloted in Qianwei village Chongming Shanghai.Water sample,which was collected from BPT,was concentrated and separated after cultivated in broth bouillon and N/P obligate media.Three kinds of strains were sieved from the vessels.After separating the bacterium,the re-screening strains A-1,F-1,B-5,C-2 were separated by electron microscope and some basic nutrient source experiments,and their optimal condition which was studied by grads setting is A-1,F-1 of 30℃for temperature,7.0 for pH;B-5 of 30℃for temperature,7.7 for pH,20%for inoculation amount;C-2 of 35℃for temperature,6.5-7 for pH,5d for best cultivated time.Under the optimum conditions,the removal efficiency of the bacteria strains is:TN of 36.4%,NO₃-N of 80.2%,and TP of 35.2%by A-1,F-1;NO₃-N 90.1%by B-5,TP of 20.3%by C-2,respectively.Three kinds of strains were studied on compound optimum in the lab.The orthogonal test was carried out to optimize degradation conditions in logarithmic growth phase,considering the affection of temperature,PH,inoculation amount and N/P.The optimum conditions of the degradation of N,P were obtained by counting degradation rates.The results showed that the optimum degradation conditions of the compound bacteria D-X as follows:30-33℃for temperature,110r/min for shaker rotating speed,pH of 7.2,inoculation amount of 20%,N/P concentration ratio of 6:1.Under the optimum conditions,the efficiency of the bacteria strains is: 97%for Total Nitrogen(TN),63%for Total Phosphor(TP),85%for CODcr,respectively,after 14-day degradation.By means of microbe separation and identification,the taxonomic status of functional bacterial strains were secured from the aspect of bacteria shape,biochemical criterion and 16S rDNA.Then it was confirmed to be Proteus mirabilis,Pseudomonas Medocina,Bacillus subtilis by gene sequencingThe mechanism of degradation,which was used chromatography of ions and standard detecting method,were SND,consolidation biological dephosphorization and so on.The primary application research on these strains was carried out in lab condition,and the affection of photoperiods and environmental conditions on the degradation of N and P were also considered. The result showed that the degradation rate was high when there was photoperiod and the t conditions of three tanks were hypoxia-anaerobic-hypoxia.While the simulated waste water, closer to true wastewater quality,was treated with the strains,the degradation effect was excellent, the removal rate of COD could reach 85%,and the quality of the water was evidently changed.