Chapter 18 - Transformation of organic contamination from wastewater into bioplastics (polyhydroxyalkanoate) by microorganisms

Abstract

Biopolymers like polyhydroxyalkanoates (PHA) are potential candidates to substitute conventional plastics produced from petroleum. PHA are polymers with plastic properties and produced from mixed microbial cultures and renewable sources, like wastewater. Thus, they are biobased and biodegradable and named as bioplastics. In general, wastewater containing biodegradable organic matter is suitable to be used for PHA production. Wastewater from different industries (mainly from the agrofood sector) has been evaluated as substrate to produce PHA. Results indicate that between 6% and 65% of the organic matter contained in the wastewater is transformed into PHA. Different bacterial populations present in the activated sludge have the ability to accumulate these PHA in transient conditions, for example, of the presence-absence of organic matter or the so-called aerobic dynamic feeding (ADF). Although the use of wastewater and microbial mixed cultures to produce PHA is increasing in interest due to the substantial reduction of costs associated to the use of a waste and the required nonsterile conditions, several challenges have to be faced before the process scale up. The increase of volume productivity and the reduction of costs during the PHA extraction step are among them.