Production of Polyhydroxyalkanoate During Treatment of Tomato Cannery Wastewater

Abstract

Polyhydroxyalkanoate (PHA) production was achieved using tomato cannery waste coupled with a mixed microbial culture during wastewater treatment. The two‐stage PHA production process comprised a sequencing batch reactor (SBR), operating under a periodic feast–famine regime, to accomplish simultaneously wastewater treatment and selection of PHA‐accumulating microbes, followed by a batch reactor for the production of PHA‐rich biomass. The SBRs were efficient at removing soluble carbon (84%), ammonia (100%), and phosphorus (76%). Meanwhile, PHA‐accumulating microbes were enriched under the SBR operating conditions, and PHA content on a cell‐weight basis was within the range 7 to 11% in nonfiltered wastewater and 2 to 8% in filtered wastewater. Subsequently, batch studies were implemented with varying loading rates, ranging from 0.4 to 3.2 food‐to‐microorganism ratios. A maximum 20% PHA content on a cell‐weight basis was obtained. Based on the experimental results, a PHA biosynthesis‐degradation kinetic model was developed to (1) aid in the design of a pilot‐ or full‐scale PHA production process coupled with wastewater treatment and (2) determine optimal conditions for harvest of PHA‐rich biomass.