The Poly(3-Hydroxybutyrate) Production From the Mixed Culture With the Leachate Obtained From Wastewater Sludge Pretreated by the Electrochemical Process

Polyhydroxyalkanoates (PHAs) are biodegradable plastics with great environmental and application value, yet high production costs, mainly from carbon sources, hinder their large-scale use. In sludge dewatering by electrochemical treatment followed by press filtration, leachate with rich organic matter is produced and considered a cheap carbon source. This study converted the leachate to volatile fatty acids (VFAs) under anaerobic fermentation at 35°C and pH 5.5. The PHA was produced from a PHA-producing mixed culture acclimated from wastewater sludge. The VFAs were fed to the mixed culture. The highest PHA content was 42% (g/g VSS). The PHA contains 55% of polyhydroxybutyrate (PHB) and 45% of polyhydroxyvalerate (PHV). When the VFAs were generated from the leachate of the sludge treated with the electrochemical process, the PHA content dropped to 17%. With the treatment of the VFAs or leachate, the PHA content was increased. The highest PHA content was up to 35% (g/g VSS). In addition, co-fermentation of VFAs and acetic acid for PHA production has also shown improvement in PHA accumulation. The study provides an alternative method for PHA production and managing the leachate produced from the electrochemical process for sludge dewatering.