Potential of waste activated sludge to accumulate polyhydroxyalkanoates and glycogen using industrial wastewater/liquid wastes as substrates

Recovery of the organics in industrial wastewaters/liquid wastes as polyhydroxyalkanoate (PHA) and/or glycogen (GLG) in waste activated sludge is a useful strategy to not only improve the resource value of waste activated sludge but also reduce the energy and cost of waste disposal and wastewater treatment. This study aimed to evaluate the potential of activated sludge to accumulate PHA and GLG using complex substrates (actual and simulated industrial wastewaters/liquid wastes) in addition to various simple organic substrates (organic acids, saccharides, and glycerol). The 24 h PHA and GLG accumulation experiments resulted in the accumulation of up to 25.5%, 6.0% and 14.1% of polyhydroxybutyrate (PHB), polyhydroxyvalerate (PHV) and GLG, respectively, from simple substrates, and up to 9.8%, 0.1% and 14.6%, respectively, from complex substrates. The results indicated that activated sludge can accumulate PHA and GLG even from complex wastewater substrates, although the accumulated PHA and GLG levels were not sufficiently high. The results also indicated that the PHA and GLG accumulation abilities of activated sludge from complex substrates can be drastically enhanced by a short-term acclimation to the corresponding substrate. This study will present the practical implications for value-added resource production through the combined use of waste activated sludge and industrial wastewaters.