Study On Biological Treatment Process For Black And Grey Water Separated From Dispersed Rural Domestic Sewage

Aiming at the scattered distribution of rural domestic sewage and the large changes in water quality and quantity,biological ecological combination process with the principle of high efficiency,low consumption and resource utilization is proposed to treat black water and grey water separated from decentralized rural domestic sewage,based on the concept of separation,sewage separating treatment and resource utilization of domestic sewage sources.Black water with high concentration of organic matter separated from rural domestic sewage enters the high efficiency Anaerobic Baffled Reactor for high efficiency anaerobic reaction.Anaerobic black water effluent mixed with grey water separated from rural domestic sewage enters the Anoxic Reactor and then enters the Waterwheel Rotating Biological Contactor for aerobic treatment.The aerobic unit returns part of the nitrifying liquid to the Anoxic Reactor to realize the function of nitrogen removal by denitrification.Focusing on operational parameters optimization and pollutants removal efficiency in biological treatment process system composed of high efficiency Anaerobic Baffled Reactor—Anoxic Reactor—Waterwheel Rotating Biological Contactor,the conclusions of the experiment are as follows:(1)The Hydraulic Retention Time and anaerobic reaction temperature of the high efficiency Anaerobic Baffled Reactor have significant effects on the removal of organic matter.The removal efficiency of COD in high efficiency Anaerobic Baffled Reactor increases with the extension of Hydraulic Retention Time and the increase of anaerobic reaction temperature.When HRT is extended from 72 h to 96 h,the increase in COD removal rate is not significant.High efficiency Anaerobic Baffled Reactor has a low effect on TN and ammonia nitrogen removal,and almost no removal of TP.(2)The COD removal rate of the Waterwheel Rotating Biological Contactor is increased firstly and decreased secondly with the extension of the Hydraulic Retention Time,and decreases with the increase of the Reflux Ratio of the nitrifying solution,and increases with the increase of temperature within a certain temperature range.The removal rate of ammonia nitrogen increases first and then decreases with the extension of the Hydraulic Retention Time.The nitrification liquid reflux ratio affects the denitrification of the anoxic unit.The COD removal by Waterwheel Rotating Biological Contactor mainly occurs in the primary and secondary Rotating Biological Contactors.The secondary Rotating Biological Contactor has the best effect on the removal of ammonia nitrogen,which is better than the removal of ammonia nitrogen by the first and third Rotating Biological Contactors.(3)The optimal operating parameters of the biological treatment process are recommended: the anaerobic reaction temperature is 33℃~35℃ and the Hydraulic Retention Time is 72 h of the high efficiency Anaerobic Baffled Reactor.Hydraulic Retention Time of Anoxic Reactor is 6.4 h.The Waterwheel Rotating Biological Contactor rotates at 4 r/min.The aerobic nitrifying liquid reflux ratio is 100% and the aerobic Hydraulic Retention Time is 3 h of Waterwheel Rotating Biological Contactor.(4)The removal rate of COD by anaerobic biological unit is 76.74% when biological treatment process is operated under the recommended optimal operating parameters.The COD value of the effluent of the whole biological treatment process is less than 50 mg/L and the effluent meets the Grade A standard of the COD project in GB18918-2002.(5)Biological treatment process runs under the recommended optimal operating parameters.The removal rate of ammonia nitrogen by aerobic biological unit is 87.47%,which is much higher than that of anaerobic and anoxic ammonia removal.The entire biological treatment process has a very poor removal effect on TN and TP.The ammonia nitrogen,TN and TP in effluent can not meet the first-class A standard of "Emission Standards for Pollutants in Urban Sewage Treatment Plants" without being processed by the subsequent constructed wetland.