The Influence Of Alkalinity Change On Organic Wastewater Treatment Using A Hybrid Anaerobic Membrane Bioreactor

The lack of water resources and serious water pollution make the quest for aneconomical and efficient water treatment process or sewage recycle technology becamea research hotspot of scholars in many countries as well as an issue that urgent need tostudy and solve.This paper is the first to combine an attached growth anaerobic reactor (AGAR)with a mounted cylinder type anaerobic membrane bioreactor (AnMBR), developed anovel anaerobic process. The sponge packing in AGAR as a medium of microbialadhesion effectively prevent the loss of activated sludge. The AnMBR, which be used toreplace subsequent aerobic tank and clarifier in the traditional process, shorten theprocess line and save the space.There are many factors that can influence the operation of the anaerobic process,such as organic loading rate (OLR), hydraulic retention time (HRT), temperature,alkalinity, etc. This paper is mainly to explore the influence of alkalinity on theoperation of the process.The seeding sludge of the AGAR.from the facultative tank of a coking wastewatertreatment plant. Using organic wastewater COD value increased from800mg/L to1500mg/L to domesticate step by step.81days after the start-up and the COD value ofinfluent is about1500mg/L, the COD removal rate of AGAR as high as80.5%, reachedthe goal of start-up.After start-up AGAR successfully, combined AGAR with a mounted cylinderAnMBR. The process was operated under the condition: the temperature was301℃,the COD value of influent was about1500mg/L, the HRT of AGAR was24h and theHRT of AnMBR was3h.After the novel process running smoothly and under the condition of four differentalkalinity (810,452,260and88mg/L), there was0.078～0.090g alkalinity (measured inCaCO3) produced as1g COD was consumed in AGAR. When the alkalinity gradient becomes lower from810mg/L to88mg/L, the pH lowered, the gas production rate andthe concentration of volatile fatty acid (VFA) increased slightly, the new process stableoperation in overall and basically was not affected by the change of alkalinity. When thealkalinity from810mg/L plunged to88mg/L, the system acidification and unable toadapt as well as recovery, While after the alkalinity, back to810mg/L, the systemrestored to the original status after23days.As the Alk0/COD0of influent were0.06～0.56, the removal rate of organics by thenovel anaerobic process could reach94%～96%, the VFA concentration in effluent was≤50mg/L. Thus Alk0/COD0=0.06was the most economical and efficient operationcondition.