The Research On The Treatment Of City Sewage By Complex Three-dimensional Electrode Coupled Biological Aerated Filter

With the development of economy and the improvement of people environmental protection consciousness, the new type of trace pollutants pharmaceutical and personal care products(PPCPs) have been found frequently in urban sewage which was treated after the secondary biochemical treatment process. These organisms which has the characteristics of persistent, enrichment and hard biodegradation not only caused the pollution to the river,and has a certain influence on human health,so we must to improve the innovation on the traditional process.In this paper, building the complex three-dimensional electrode polarity coupled biological aerated filter reactor according to the operation features of complex three-dimensional electrode polarity and aeration biological filter, the treatment efficiency of simulation city secondary sewage which contains the typical PPCPs has been discussed and carry on further research from two main aspects of the filter operation and microbial diversity.Gamma alumina was selected as the carrier of particle electrode, the oxide state of transition metal Mn, Fe, Sn as the catalyst active component. Through the pretreatment of the carrier,dipping, drying and roasting process, one-component and different metal oxide ratio of load type particle electrode were prepared. In the process of study on the removal effect to the phenol concentration of 200mg/L,we found that best experiment condition of Mn: Sn = 2:1 particle electrode to remove phenol is: the plate electrode spacing 5 cm, 0.1 mol/LNa2SO4 electrolyte, pH5.16, removal efficiency as high as 80%.The complex three-dimensional electrode polarity coupling aeration biological filter reactor is constituted of the complex three-dimensional electrode polarity which is filled the successful preparation particle electrode and the lower aeration biological filter with zeolite.In addition, introduce the domesticated activated sludge for hanging membrane, compared with ordinary aeration filter at the same time. The experiment shows that the removal rate of ammonia nitrogen and CODcr by the complex three-dimensional electrode polarity more than 80% and more stable after 20 days. but the removal of ammonia nitrogen and CODcr by ordinary biological aerated filter has a greater fluctuation.Under the action of electric current, the membrane permeability of microbial cell in the electric biological coupling filter was enhanced and accelerated the absorption and utilization of nutrients,promoted the growth of microorganisms,so the complex three-dimensional electrode polarity coupling aeration biological filter shows the better hang membrane start-up speed and stability.In the stable operation phase of the filters stage, the influence of current intensity, hydraulic retention time, target PPCPs organic matter concentration for the complex three-dimensional electrode polarity coupled biological aerated filter reactor was studied.The study shows that when current intensity was 0.5A, the electrical catalysis promoted the reaction rate and degree of catalytic reaction, the average removal rate of CODcr,ammonia nitrogen and TOC in the complex three-dimensional electrode polarity coupled biological aerated filter is 92.3%,91.1% and 85.8%,significantly higher than the ordinary biological aerated filter.The removal rate of conventional index by two groups of filters is higher when the typical target PPCPs organic matter concentration is 0.1 mg/L,but the catalytic oxidation of three dimensional electrode of complex three-dimensional electrode polarity coupled biological aerated filter has the higher removal of CODcr, ammonia nitrogen and TOC than ordinary biological aerated filter.Keep the hydraulic retention time of 3.5h,the contact time of sewage water in filter and the microbial was increased, and the catalytic degradation of pollutants by three-dimensional electrode polarity were more fully,the best average removal rate of CODcr, ammonia nitrogen and TOC of complex three-dimensional electrode polarity coupled biological aerated filter are 95.1%, 91.9% and 86.8%,respectively.Under the optimum condition of stable operational stage, because of ibuprofen and bezafibrate is easy biodegradate than carbamazepine, so the two sets of filter on the removal rate of ibuprofen and bezafibrate were slightly higher, the difference is small, the average removal rate of carbamazepine are 38.8% and 17.6% respectively.In order to investigate the temporal variation characteristics of filter, the change of ammonia nitrogen and CODcr of two groups of filters are studied.Experiment shows that the removal of ammonia nitrogen and CODcr by the two groups of filter have a rising trend along the flow direction filter, the rate of rise of complex three-dimensional electrode polarity coupled biological aerated filter is faster than the ordinary biological aerated filter. After the filter backwash removal rate of ammonia nitrogen, CODcr and TOC by two groups of filters are reduced to some extent, the recovery time of complex three-dimensional electrode polarity coupled biological aerated filter is shorter.Through high-throughput sequencing to illustrate the diversity of microorganisms in filter. Found that community structure in the complex three-dimensional electrode polarity coupled biological aerated filter is different from ordinary biological aerated filter.Biofilm of anode area in three-dimensional electrode exist deformation of bacteria of the genus and Ferruginibacter door, and nitration spiral bacteria door Nitrospira, Ferruginibacter genus, utricle Nannocystis bacteria have the function of the degradation of organic matter. Due to the influence of three dimensional electrode type bacteria we found that the lower of the electricity biological coupling filter strict advantage bacterium group of rotting spirochete Saprospiraceae,yellow bacillus genus Flavobacterium and Zoogloea bacteria micelles which can oxidate the organic matter.The three dimensional electrode of the complex three-dimensional electrode polarity coupled biological aerated filter has the lower similarity in different microbial flora species abundance and flora, lower part of the complex three-dimensional electrode polarity coupled biological aerated filter presents contrary state, the different environment between the top and bottom in the complex three-dimensional electrode polarity coupled biological aerated filter caused the higher difference in similarity level, different from ordinary biological aerated filter.