Research And Development Of Household Integrated Sewage Treatment Equipment And Optimization Of Its Operation

As of 2020,only 34.87%of China’s villages have treated domestic sewage,and the treatment rate still has great room for improvement.To further increase the rate of sewage treatment in rural areas,the main focus should be on decentralised treatment.However,most of the current decentralised treatment still uses low-cost,simple treatment technology,which makes it difficult to achieve stable effluent standards.Integrated wastewater treatment equipment is the main development direction for future decentralised treatment.To promote the widespread use of integrated equipment,more research is also needed to reduce investment,operating costs and operational and maintenance difficulties.In this study,a simplified anaerobic biofilter,anoxic biofilter and biological contact oxidation tank are combined according to the inverted A~2/O process to develop a household integrated domestic wastewater treatment equipment.The filler in the anaerobic biofilter and anoxic biofilter was identified through comparative tests as SPR-1 suspension filler.Biofilm is the main form of microorganism in the system,which is conducive to the growth of nitrifying bacteria and is effective in nitrogen removal.There is also a small amount of suspended sludge,so it also has a good phosphorus removal effect.The optimum operating parameters for this equipment were determined through a series of single-factor tests.The equipment was then operated continuously and automatically for 15 days under the conditions of 5.3 mg/L dissolved oxygen in aerobic pool 1,4.3 mg/L dissolved oxygen in aerobic pool 2,400%reflux ratio of nitrification solution,13.3 h hydraulic retention time,20-22°C water temperature and 6.5-8.0 p H value.The average concentrations of COD,ammonia nitrogen,total nitrogen and total phosphorus in the influent water for these 15 days were 244.05 mg/L,40.16 mg/L,42.23 mg/L and 1.76 mg/L respectively,with average removal rates of 90.71%,96.10%,74.44%and 88.87%respectively.The effluent quality can stably achieve the grade I Class A standard of Discharge Standard of Pollutants for Municipal Wastewater Treatment Plan(GB18918-2002).The operation of the pilot equipment in rural households has shown that the equipment has the advantage of high automation and simple operation and maintenance.The equipment is suitable for single-family domestic wastewater treatment as it can stably remove COD,nitrogen and phosphorus without professional staff on duty and has good removal rates.