The Study On A Novel Artifical Ecological Biofilm Reactor For Uncentralized Wastewater In Rural Areas

In recent years,with the rapid development of China’s economic level,facilities of urban sewage treatment have been greatly improved and the efficiency of water resources use have basically fulfilled the requirements of modernization.However,in the vast rural areas,especially in poor areas,due to the dispersion of population living,the difficult of drainage network construction and the high-cost,the drainage infrastructure construction is relatively lagging.The decentralized wastewater in rural areas are usually directly discharges instead of entering the pipe network.This kind of situation causing serious pollution to the local and downstream ecological environment.Our research group is concerned with the largest problems of “difficulty in wastewater collection,difficult maintenance of equipment,high treatment cost”,and a novel Artificial Ecological Biofilm reactor Reactor was designed to treating decentralized waste water.This reactor is suitable for rural areas of China for its low-cost and easy-maintenance,and it can be used for treating waste waters of different qualities and volumes.The chemical oxygen demand(COD),nitrogen removal efficiency,and the microbial community structure were evaluated in different stages of the Artificial Ecological Biofilm reactor Reactor for 50 days.The results obtained for each stage were compared to those of other stages.The COD and ammonium nitrogen(NH3-N)removal efficiency remained at approximately 80% after 20 days and three stages played different roles in removal of specific pollutant.High-throughput sequencing was used to investigate the composition of the microbial community in the treatment system.The microbial richness of stage 1 was higher than that of stage 2 and it indicated that the raw waste water had a higher biodegradability after stage 1.The microbial diversity in the stage 1 and stage 2 were similar to each other;but were much higher than that in stage 3.The major classes present of three stages Artificial Ecological Biofilm reactor Reactor were Alphaproteobacteria(average abundance of 21.7%),Betaproteobacteria(20.8%),Gammaproteobacteria(12.2%),Sphingobacteriia(9.5%),Cytophagia(8.0%),Acidobacteria_Gp4(6.3%),Acidobacteria_Gp3(6.0%),Flavobacteriia(2.9%),Deltaproteobacteria(2.6%),ML635J-21(2.1%),Saprospirae(1.8%),and Bacteroidia(1.2%).Their distribution is significantly different in each stage,and this difference leads to their functional differences.Through comprehensive query of other biofilm reactor and contact oxidation method,combined with the characteristics of Artificial Ecological Biofilm reactor Reactor,a variety of composite fillers are used to improve the reactor,achieving efficient,small and portable design goals.The operating efficiency is increased by 18 times,the COD removal efficiency is increased to 90%;the effluent is as low as 50 mg/L to reach the national first-class A emission standard;the ammonia nitrogen removal efficiency is 100%;and the effluent contains almost no ammonia nitrogen.The size of reactor is reduced to half a person scale and it can be installed by on adult in one hour.This kind of characteristic is especially suitable for practical applications in rural areas.Light and dark conditions have little effect on the efficiency of the improved reactor operation.In other words,the reactor can perform high-efficiency in both light and dark conditions.However by scanning electron microscopy,high-throughput sequencing and FAPROTAX functional sequencing studies show that light and dark conditions have great differences in the way of pollutant removal.The suspended padding in the dark condition is the main place of nitrification reaction,and the soft carrier under the light condition is the main place for denitrification,while non-woven fabrics mainly adsorb ammonia nitrogen,nitrate and nitrite.