Study On Treatment Of Rural Domestic Sewage By Algal-bacterial Biofilm

With the rapid development of China's rural areas and the continuous improvement of residents'living standards,the discharge of rural domestic sewage has gradually increased the problem of rural water pollution.The integrated purification tank technology suitable for the treatment of domestic sewage in rural areas of China is developing rapidly,but in practical applications there are problems such as excessive installation and operation costs,difficulty in operation and maintenance,and standards and standards to be improved.In this paper,BC bio-filler was used as carrier to carry out algal-bacterial biofilm hanging film experiment,and the efficacy of algal-bacterial biofilm treatment to simulate rural domestic sewage and anaerobic+algal-bacterial biofilm treatment of actual rural domestic sewage were studied,providing basis for the development of a new integrated domestic sewage purification tank based on algal-bacterial biofilm technology.The main conclusions are as follows:?1?Using chlorella and aerobic denitrifying bacteria as the microorganisms used in the experiment,the effects of suspended algae,bacteria alone and algal-bacterial symbionts to simulate rural domestic sewage were compared.The results showed that the COD,ammonia nitrogen?NH₄⁺-N?and total nitrogen?TN?in algal-bacterial symbionts system were lower than that of algal or bacteria alone system in simulating rural domestic sewage.The removal rate of COD,NH₄⁺-N and TN in algal-bacterial symbionts system were 84.40%,67.07%and 49.94%respectively.But the phosphorus?TP?in algal-bacterial symbionts system was slightly higher than that of algal alone system in simulating rural domestic sewage.The removal rate of TP in algal-bacterial symbionts system were 64.46%.?2?The BC-type bio-filler was used as a carrier to carry out the film-hanging experiment.The effect of adding sequence,light intensity and aeration time for system treatment on simulating rural domestic sewage were investigated.The removal rate of COD,nitrogen,phosphorus were considered.Best experimental conditions are as follows:adding algae and bacterial at the same time,hanging light with 4000 lux of light intensity,adding aeration 1 hour a day.Under the best reaction conditions,when the system simulates rural domestic sewage,the removal rate of COD,NH₄⁺-N,TN and TP were 84.40%,67.07%,49.94%and 54.46%respectively.?3?When the anaerobic+algal-bacterial biofilm system are used to treat actual rural domestic sewage,the effluent water quality can reach the first-class B standard of the Emission Standard for Pollutants in Urban Sewage Treatment Plants?GB18918-2002?,and some indicators can reach the first-class A standard.The highest removal rates of COD,NH₄⁺-N,TN and TP were 91.18%,89.85%,81.34%and 54.46%,respectively.Taking anaerobic+algal-bacterial biofilm as the main reaction unit,the integrated domestic sewage purification device is designed according to the quality of rural domestic sewage water,water quantity and treatment experience.The process flow is:influent?filter tank?anaerobic filter bed tank?algae-bacterial reaction tank?sedimentation tank?disinfection tank?effluent,and can be implemented after technical feasibility analysis.