Influence Of Oxidation-reduction Potential On Distrubition And Variation Of End Products In The Process Of Starch Hydrolysis And Acidification

Nowadays, hydrolysis and acidification process has been widely applied in wastewater treatment field. However, mechanism of this process is still so far unclear due to the diverse bacteria and complex bioprocess in this process. Up to now, efficient operation of this process can not be realized as lack of appropriate control parameter. Therefore, feasibility and advantage of ORP, under microaerobic environment, as a control parameter was studied via introducing mixed gas, composed of oxygen and nitrogen, into system. Meanwhile, this research investigated the specific dehydrogenase activity of microorganism and distribution of end products in the process of starch hydrolysis and acidification at different ORP levels.Comparing with DO, under microaerobic environment, ORP can reflect redox state change more sensitive, precise and timely. Meanwhile, the trend of profile on ORP can indicate the end point of acidification process as acidification process had been ended while ORP fell off to a small range.The fastest rate of hydrolysis reached at ORP=-100mV with rate constant0.0952min-1. Under this environment, activity of microorganism was highest. Daily average sludge growth rate and specific dehydrogenase activity were0.383g·d-1·L-1and433.7mgINTF/gMLSS·h respectively, which indicated that the optimum ORP level for acid-producing bacteria, in this research, is at ORP=-100mV.Acetate decreased greatly from1514.7mg/L to471.1mg/L when ORP increased from-250mV to-50mV. Meanwhile, propinate increased from718.7mg/Lto993.5mg/L beacuse of the improvement of propionate production capacity. In the process of regulation, carbon recovery rate dropt from80.3%to68.6%. According to carbon metabolic pathway analysis, it was found that the activation of TCA cycle incurred the variation of end products concentration in the process of acidification at high ORP levels.