Study Of The High Inorganic Suspended Solids On The Efficiency Of Aeration Tank In The Pilot-scale Experiment

With the acceleration of urbanization,the inorganic suspended solids content of wastewater treatment plant in urban areas is relatively high,resulting in MLSS of biochemical systems being generally higher than the theoretical design value.MLVSS/MLSS values are between 0.28 and 0.5,much lower than the theoretical value of 0.7.Especially cancelled primary sedimentation tank of sewage treatment plant,this phenomenon is more pronounced.When the domestic wastewater with high influent inorganic suspended solid?ISS?enters the biochemical system,the inorganic content will increase and accumulate in the system.The inorganic suspended solids effective on sewage biochemical system which few relative studies have been done.The polit was decided to be carried out in a sewage plant in Changchun New Area which to study the high ISS/COD influent effect on the sludge characteristics t and operation energy consumption and cost analysis during the winer and summer.This problem can not be ignored.The main research is as follows:In the Changchun New District WWTP,the suspended solid in winter is relatively less with the average concentration of 1188mg/L,the suspended solid in summer concentration of 2656 mg/L,because of the increase of summer rainfall and the increase of residential water consumption lead to this phenomenon.Winter ISS/COD average 0.7,significantly lower than the summer average of 2.7.The MLSS/MLVSS fluctuated in the range of 0.44-0.55,which was below 0.75theoretical value.The SVI value fluctuated between 100¹25m L/g.During the summer when a large amount of high-inorganic suspended solids entered,the 50%particle size distribution was found to be in the range of 70-150?m.The ISS/COD of the influent water fluctuated greatly and the MLSS of the system increased sharply from 6000mg/L to 10000mg/L,the value of MLSS/MLVSS dropped to 0.28,the impact of inorganic suspended solids and floc density increased,leading to a sharp drop of SVI to 30 m L/g,the particle size of 30?m was smaller than the normal size of 80?m.The effect of large amount of inorganic suspended matter in summer on reactor sludge activity is obviously greater than that in winter.In winter,the suspended inorganic matter enters into the reactor,and the influent COD,TN and TP will increase,which will help the system to improve the removal efficiency of COD and TP.TN is affected by low temperature in winter.The removal efficiencies of COD,TN and TP in summer system were significantly increased,while the removal efficiency of NH₄⁺-N was not obvious.COD,TP,NH₄⁺-N effluent quality meet the requirements of the national class V water body index.And no follow-up depth of the structure,reducing operating costs.MLVSS/MLSS is reduced for high inorganic influent conditions,and the system ensures that effluent quality requirements the emission standards by increasing the sludge concentration.The oxygen mass transfer inside the reactor showed a downward trend,DO significantly decreased,a decrease of 70%.Inorganic density,small specific surface area,in the biochemical pool to maintain the same state of suspension,the need for greater mixing rate,a small experiment shows that adding fine inorganic matter to maintain the same suspension,which need to increase of 20%the stirring power.Reactor with nitrification liquid reflux device and biological treatment device,lower operating costs.At the same time the reactor only rely on biological phosphorus removal,there is no chemical phosphorus removal measures.Can provide guidance for the actual sewage treatment plant energy saving.