Production of PHAs with enhanced properties from sugar-based wastewater in a two stage process

The experimental design of the study was based on two different microbial processes, i.e. anaerobic fermentation of a sugar-based wastewater via mixed acidogenic cultures and aerobic polymerization of the produced acids and alcohols for poly-hydroxy-alkanoates (PHAs) production, via enriched cultures. For the first stage of the combined process, a continuous up-flow column reactor (UFCR) and a continuous stirred tank reactor (CSTR) were developed. For the optimization of the performance of both reactors, the effect of main parameters influencing the distribution of the produced acids were investigated. The liquid effluent of the reactors, containing fatty acids and ethanol were forwarded to the second stage of the combined process. A sequential batch reactor (SBR) was used for the second, aerobic stage of PHAs production. The inoculum used for the start up of SBR was an enriched culture that was developed by thermally pretreated soil, subjected to nutrient limitation.