Study On The Treatment Efficacy Of Potato Starch Wastewater By Aerobic Granular Sludge

Compared with the traditional activated sludge technology,AGS has the advantages of good sedimentation performance,strong anti impact load capacity and high sludge concentration.It has been gradually put into the wastewater treatment in practical engineering from theoretical research.But there are some problems in aerobic granular sludge technology,such as long culture period,high requirements for water conservancy conditions,high requirements for nutrients in the inflow and poor stability.Potato starch wastewater is a kind of wastewater produced in potato processing industry.Most of the wastewater from potato starch production is concentrated in two months of each year,with short discharge time,high pollution load and large discharge.These characteristics greatly strengthen the difficulty of potato starch wastewater treatment.At present,the treatment of potato wastewater at home and abroad is mainly through anaerobic,coagulation and sedimentation,adsorption and other ways,and aerobic biological treatment technology is rarely used.This paper studies the treatment efficiency of aerobic granular sludge to potato starch wastewater,including three stages:cultivation,domestication and operation efficiency of aerobic granular sludge.Different sludge start-up reactors were used in the culture stage to investigate whether the pre-adding aerobic granular sludge could promote the granulation process.After the granulation of the sludge,the aerobic granular sludge was domesticated with potato starch wastewater.After the acclimation stage,the experiment was carried out.During the operation,artificial water distribution of simulated potato starch wastewater was used as the water inflow,and the treatment efficiency of potato starch wastewater was analyzed under different COD concentration and different C/N ratio.In the culture stage of aerobic granular sludge,RN1 formed aerobic granular sludge with an average particle size of more than 0.2mm when the reactor was running for 20 days,while the time for the formation of aerobic granular sludge in RN2 was 5days ahead of time;With the continuous operation of the reactor,the average particle size of aerobic granular sludge continued to increase,and the average particle size was0.48mm and 0.51mm when the culture reached 40 days;It is concluded that adding aerobic granular sludge in seed sludge will shorten the culture time of granulation,but with the experiment,the advantages of RN2 reactor are less and more obvious,which is basically the same as RN1;Both groups of reactors formed aerobic granular sludge with good settling performance in a short time.After 40 days of domestication,aerobic granular sludge successfully adapted to high concentration potato starch wastewater.After the acclimation stage,the sludge concentration of the system was 8764mg/l and SVI₅was 34.54ml/g,and the removal efficiency of COD,TN and NH₄⁺was 87.7%,63.5%and 93.2%respectively.When the ratio of c/n of the influent is controlled,the removal rate of COD is over 90%when the concentration of the water is changed.The removal rate of TN is 60%to 75%,and the removal rate of COD is 1600mg/L and TN is 50mg/L.the reactor has the best removal effect.The removal rate of COD is 92.9%and TN removal rate is 72.0%.When the influent cod is controlled,the removal of COD is less affected by the C/N ratio when the c/n ratio is changed,and the removal rate can still be kept at about 90%under the condition of 2100mg/L water;The removal rate of TN is limited by denitrifying bacteria.When the C/N ratio is low,denitrification can not be performed completely,which leads to the accumulation of nitrogenous nitrogen and nitrous nitrogen in the system,and the removal effect of TN is not good.The removal rate was 73.5%.Through the analysis of the biological community structure in aerobic granular sludge culture,the alpha diversity of the system is in a downward trend during the formation of aerobic granular sludge.The species diversity and abundance of flocculent activated sludge and aerobic granular sludge system are different.With the process of sludge granulation,the microbial species richness of granular sludge decreases,Community diversity also decreased;Acinetobacter,Amaricoccus,Candidatus?Microthrix,Paracoccus and delftia gradually became dominant bacteria in aerobic granular sludge culture,mainly with the bacteria related to EPS secretion and denitrification.