Aerobic Granular Sludge Application In A Company Demestic Wastewater Treatment Research

Aerobic granular sludge with good sedimentation performance,high biomass,impact resistance and other advantages has become a research hotspot.Most of the research and application of aerobic granular sludge technology are sequential batch reactors,and the research of continuous flow aerobic particles in sewage biological treatment is getting more and more attention.At present,there are no reports on the application of continuous flow aerobic granular sludge technology.In this study,a pre-anoxic-anoxic-anoxic-aerobic double-sedimentation tank process was used to treat the domestic sewage of a certain enterprise with low temperature.Aerobic granular sludge was successfully cultured from dewatering sludge of sewage treatment plant through air stripping reflux and double-sedimentation tank.The average COD_Cr,ammonia nitrogen（NH₄⁺-N）and TP of raw sewage water was170mg/L,12.9mg/L and 2.6mg/L respectively.Running 140 days,the water temperature below 15℃is 120 days,the lowest temperature is 5℃.The average particle size of granular sludge in the reaction tank was 92.74±2.5μm,and the particles above 200μm accounted for about 40%.MLSS reached 3945mg/L,and SVI₃₀ was 65.9mL/g.The removal rates of COD_Cr,NH₄⁺-N,TN and TP in the system were 80%,90%,70%and90%respectively,and the main pollutants in effluent met the first-level A emission standard of"pollutant discharge standard for urban sewage treatment plant".Inoculation of dehydrated sludge can achieve more"crystal nucleus"production as soon as possible,which is conducive to the formation of aerobic granular sludge.The use of air stripping reflux can avoid the crushing of sludge agglomeration,and pre-hypoxia consumes dissolved oxygen of air stripping reflux,which is beneficial to the removal of phosphorus.The double-sedimentation tank can effectively separate the sludge of aerobic tank into heavy sludge and light sludge,and wash out the light sludge to realize the"selective pressure"mechanism of aerobic granular sludge formation.The treatment scale of this device can reach 12-24 tons/day,the total construction investment is 11,193 thousand yuan,the installed capacity is 6.2 kilowatts,the operation cost of treating tons of water is 1.089 yuan/ton,which is technically and economically feasible.The results show that the process can form aerobic granular sludge to a certain extent,and the operation is stable,and the effect of nitrogen and phosphorus removal is good.