Enrichment of Plasticicumulans acidivorans at pilot-scale for PHA production on industrial wastewater

•The maximum PHA content reached was 0.76gPHA/gVSS (in accumulation experiments on wastewater).•It appeared that ethanol in the fermented wastewater had a negative influence on the PHA production and that ethanol consumption lead to the production of another storage compound.•The difference between pilot-scale results from this study (around 70% PHA) and lab-scale results from previous studies (around 90% PHA) could be explained by the presence of solids in the substrate, the presence of a side population, and the formation of non-PHA storage from ethanol. A PHA producing microbial culture dominated by Plasticicumulans acidivorans was enriched in a pilot plant using fermented wastewater from the Mars candy bar factory. The pilot plant comprised (1) anaerobic fermentation, (2) enrichment of a PHA-producing microbial community and (3) accumulation for maximization of the cellular PHA content. After anaerobic fermentation, the wastewater contained mainly VFAs (0.64±0.15gCOD/gCOD) and ethanol (0.22±0.13gCOD/gCOD). In the enrichment reactor (cycle 12h, SRT 24h) a feast-famine pattern was established with a feast phase of around 35±5min. The culture was able to accumulate 0.70±0.05gPHA/gVSS. The difference with previous lab-scale results from P. acidivorans, in which a PHA content of 0.90gPHA/gVSS was achieved, could be attributed to the presence of solids in the influent, the growth of a side population and the accumulation of non-PHA storage compounds that appeared to be related to ethanol consumption.