Advanced Treatment Of Secondary Effluent

The secondary biological treatment for municipal sewage is limited,so biodegradable organic matter is still in secondary effluent.Although secondary effluent reached the national emission standards in a certain extent,it will break the water quality of natural water if directly discharged into natural water.In this paper,based on the lateral biological aerated filter,a wastewater treatment device called sand wall was put forward.Based on the shortage of sand wall,a novel biological sand filter was put forward for the advanced treatment of secondary effluent.This paper mainly studied the characteristics of the forming film,optimization of operating conditions,the characteristics of treatment for wastewater and microbial diversity in sand wall.It was concluded that the way of forming film was sludge inoculation,the cycle was 27days;the optimum aeration was 5.4 L/h,the hydraulic load was 9.9×10^-3 m³/?m²·h?,the chemical oxygen demand of secondary effluent from wastewater plant was reduced from 14.1mg/L to 10.1 mg/L;analysis of microbial diversity showed that the main phylums were Proteobacteria,Bacteroidetes and Firmicutes,Chlorobi,main genus was Chlorobium.This paper mainly studied the characteristics of start-up membrane,the optimization of the operating conditions,characteristics of backwash,the efficiency of treating for the secondary effluent,the culturable microorganisms and microbial diversity in novel biological sand filter.The way of forming film was sludge inoculation,the cycle was 43 days;the best aeration,influent load,height of packing were 48 L/h,0.43 m³/?m²·d?,120 cm respectively;backwash mode was automatic washing,cycle of backwash was 6 months,the best flow of washing sand was 17.10 L/h;for self-made secondary effluent,secondary effluent from wastewater treatment device and actual wastewater plant,COD was reduced from 85 mg/L?76 mg/L?12mg/L to 13 mg/L,18 mg/L,8.9 mg/L respectively,ammonia nitrogen was reduced from 5.2mg/L?10.6 mg/L?0.9 mg/L to 3.7 mg/L,0.2 mg/L,0.2 mg/L respectively,which was far below 50 mg/L for COD and 5 mg/L for ammonia nitrogen in national standard;cultured microbes were Klebsiella pneumoniae,Bacillus cereus,Bacillus toyonensis,Bacillus anthracis,Bacillus thuringiensis,Bacillus lysine.Analysis of microbial diversity showed that the main phylums were Proteobacteria and Bacteroidetes,the main genus was Denitratisoma.