Effect of pH and Alkalinity on Operation of Anaerobic Baffled Reactor

A 4-compartment anaerobic baffled reactor(ABR) with an effective volume of 28 L was used to treat soybean processing wastewater.The influence of pH and alkalinity on the operation of ABR was investigated.The operation results for 72 d indicated that the reactor attained good operation effect in the early stage of start-up by adding alkaline to the influent.pH and alkalinity were controlled at 6.0 to 7.0 and 1 000 to 1 300 mg/L,respectively.After 45 d of startup without adding alkalinity to control pH of the influent,the reactor could also run well.However,slow increase of propionic acid in the start-up stage was observed.In continuous operation stage of ABR,the pH of each compartment was 4.5 to 6.0,5.5 to 6.8,6.8 to 7.2,and 7.1 to 7.3,and the alkalinity was 1 000 mg/L to 1 400 mg/L.The fermentation product in the effluent was less than 100 mg/L(acetic acid was more than 90%),and the removal rate of COD was above 90%.