Effect of Pre-acidification on UASB Treatment of Low-strength Starch Wastewater: Performance and Surface Properties of Granular Sludge

摘要

Starch is one of the most common substances in the waste stream from the food manufacturing industry. In this study, a comparison with single-stage up-flow anaerobic sludge blanket reactor (UASB) and two-stage (pre-acidification+UASB) system in lab scale was conducted by feeding with the starch as a sole organic source. The anaerobic treatment performance and differences in surface characteristics on granular sludge from the two systems starch anaerobic treatment in low-strength were determined. The organic loading rate (OLR) was in a range of 1.0 to 8.0g-Chemical Oxygen Demand (COD)/L/d. As a result, the COD removal efficiencies were higher than 80% in both of the two systems when the OLR lower than 4g-COD/L/d. Significant foaming with the sludge floating-up was observed in the single-stage UASB when further raised the OLR to 6.0g-COD/L/d. The observation by scanning electron microscopy revealed that fibrous membrane structure formed on the granular sludge in the single-stage UASB. The granular sludge in the two-stage process had a relatively clear outline and good settle abilities in each of OLR conditions.