Deciphering the Biodegradation Mechanisms of Starch Wastewater and Microbial Community Evolution in an Upflow Anaerobic Sludge Blanket (UASB) Reactor in the Presence of Sulfidogenesis Process

摘要

A lab-scale upflow anaerobic sludge blanket (UASB) reactor was carried out to investigate the influence of sulfidogenesis process on the degradation of starch wastewater (1000 mg COD L~(-1)) and bioenergy conversion. Biochemical properties of granules are of vital importance to UASB performance. This study characterized the granules cultivated at different COD/SO_4~(2-) ratios to elucidate the influence of sulfidogenesis on starch wastewater biodegradation kinetics and process stability. Suitable sulfate addition enriched granular microecosystems and stimulated the secretion of extracellular substances, facilitating cells cohesion and sludge aggregation. The percentage of granules larger than 2.8 mm increased from < 10.0% to 58.8-69.4% with decreasing COD/SO_4~(2-) ratio from 10 to 2. Starch-fed granules tended to grow flagella-like filaments on the surface. The filaments overwhelmed by hydrophilic biopolymers had high affinity for biogas-bubbles and water-molecules aggravating granule floatation and washout. 16s rRNA gene analysis revealed that decreasing COD/SO_4~(2-) ratio shifted Syntrophobacterales to Desulfovibrio, which co-worked with Methanosaeta while suppressing Methanobacterium thereby altering starch bioconversion routes. Decrease in Syntrophobacterales caused propionate accumulation and slight process upset.