Rapid Enrichment of Polyhy droxyalkanoates-Accumulating Bacteria from Activated Sludge by Aerobic Dynamic Discharge Process

摘要

The transformation of wastewater organics into polyhydroxyalkanoates (PHA), which are bacteria-derived bioplastic materials, in waste activated sludge has been attracted as a promising approach to promote the resource and energy recovery in municipal wastewater treatment plants (WWTPs). However, because PHA-accumulating ability of activated sludge is generally low, the enrichment of PHA-accumulating bacteria is required for practical applications of PHA production in WWTPs. Recent study proposed that aerobic dynamic discharge (ADD) process, which imposes ecological selective pressure by consecutive shifts of external carbon source accessibility (feast) and unavailability (famine) and physical selective pressure by short-time settling and withdrawal, can effectively enrich PHA-accumulating bacteria in a short period. Therefore, this study aimed to establish a rapid enrichment method within 2 days by ADD process. To optimize the nutrient feeding conditions, enrichments of PHA-accumulating bacteria were conducted by ADD process with the nutrient feeding ratios (%) of 0/100, 25/75, 50/50, and 75/25 at the beginning of feast/famine phases. The results indicated that the nutrient feeding condition during enrichment largely affects the PHA-accumulation ability of resultant enrichment culture, and that a nutrient feeding ratio of 0/100 is the most suitable for rapid enrichment of superior PHA-accumulating bacteria by ADD process.