Anaerobic Treatment Process Of Potato Starch Wastewater In A Complete Mixed Sequential Batch Reactor

Potato starch wastewater(PS W)is produced during the processing of potato starch,which has the characteristics of high concentration and heavy pollution,Direct discharge of PSW into waterbodies will cause serious damage to the ecological environment.Therefore,it is essential to dispose PSW properly.The anaerobic biological method has many advantages in the treatment of PSW:(1)Removing most of the organic pollutants with a high removal efficiency and low energy consumption;(2)Producing biogas,which is a clean energy source.In this study,the anaerobic treatment of PSW was studied in a complete mixed sequential batch reactor.The treatment performance of ASBR to PSW under different temperature conditions was studied.Simultaneously,the effects of different exogenous additives on the anaerobic treatment of organic matters were studied by parallel comparison experiments.The main conclusions of this study are as follows:1.Effects of varying temperarture on ASBR operation(1)At room temperature,the reaction temperature was easily to change,and OLR that the reactor can withstand was 1 kg/(m3·d),which cannot exceed 2 kg/(m3·d).When influent COD was about 15000 mg/L,effluent SCOD and TCOD were 1300 mg/L and 2800 mg/L respectively,and corresponding removal efficiencies reached 90%and 85%,respectively.At 30 ?,OLR was up to 7 kg/(m3·d),effluent SCOD and TCOD basically stabled at around 700 mg/L and 1500 mg/L,the corresponding removal efficiencies reached 95%and 90%respectively.At 22 ?,the OLR that reactor could afford was more than 3 kg/(m3·d),effluent SCOD and TCOD stabled at 1400 mg/L and 3000 mg/L,the corresponding removal efficiencies were 92%and 82%,respectively.Temperature fluctuation was the main reason that the reactor cannot withstand a load of 2 kg/(m3·d)at room temperature.Controlling the temperature at a constant value was crucial for anaerobic treatment of PSW.(2)The addition of buffer was beneficial to control the pH value of the reactor.Since the biogas production is affected by the reaction temperature and the concentration of organic matter in the reactor.And under of a moderate temperature condition of 30?,with stable opreation of the reactor,there is a function relationship between the biogas production(Y)and OLR(X)as:Y=2019.7+59.6 X.Therefore,the operation performance of the reactor can be roughly obtained by comparing the actual measured biogas amount and calculated value.Ammonia nitrogen concentration in the effluent was 600-1300 mg/L,which didn't have inhibitory effect on anaerobic reaction.The increase of TSS in the effluent was mainly due to low temperature.And excess sludge loss should be avoided to maintain the stable operation of ASBR.2.Effects of exogenous additives on the treatment of organic matters(1)The results of parallel comparison experiments showed that,the effluent SCOD of the blank control group decreased from 1300 mg/L to less than 500 mg/L over time,indicating that the reactor's ability to remove pollutants was continuously enhanced.After adding activated carbon,the effluent SCOD was reduced to about 350 mg/L.The addition of activated carbon in appropriate amount was beneficial to the stability of anaerobic treatment and the reduction of effluent SCOD.Fe3+ in the influent had a little effect on the removal of organic matters at the dosages of 3.5 mg/L and 10.4 mg/L,and the increase of Fe3+ concentration was beneficial to the organic matters removal.The addition of Ca2+ at the concentrations of 3.6 mg/L and 10.8 mg/L had no significant effect on the reduction of SCOD and the removal of organic matters.(2)The complete mixed sequential batch reactor had an excellent pH buffering capability.The concentration of ammonia nitrogen in the effluent was mainly affected by the concentration of nitrogen-containing organic matters in the influent.Activated carbon had an adsorption effect on ammonia nitrogen,while adding FeCl3 and CaCl2 decreased the ammonia concentration of the effluent.After the addition of activated carbon,there was no significant increase in biogas production,which confirmed that activated carbon mainly played the role of adsorption.The biogas production under an addition of Fe3+ at 10.4 mg/L was slightly higher than that of 3.6 mg/L,indicating that increasing the concentration of Fe3+ can indeed improve the anaerobic treatment efficiency.Different additives had a positive effect on reducing the turbidity of effluent.The most effective addition is activated carbon,followed by Fe3+ and Ca2+.The surface of activated carbon tended to adhere to microorganisms,which was conducive to the formation of granular sludge.Fe3+ and Ca2+ had no significant effect on improving the sedimentation performance of sludge.