No abstract

Pilot and prototyping scale investigations were undertaken in order to evaluate the technical feasibility of producing value-added biopolymers (polyhydroxyalkanoates (PHAs)) as a by-product to essential services of wastewater treatment and environmental protection. A commonly asked question concerns PHA quality that may be expected from surplus biomass produced during biological treatment for water quality improvement. This paper summarizes the findings from a collection of investigations. Alongside the summarized technical efforts, attention has been paid to the social and economic networks. Such networks are needed in order to nurture circular economies that would drive value chains in renewable resource processing from contaminated water amelioration into renewable value-added bioplastic products and services. We find commercial promise in the polymer quality and in the process technical feasibility. The next challenge ahead does not reside so much any more in fundamental research and development of the technology but, rather, in social-economic steps that will be necessary to realize first demonstration scale polymer production activities. It is a material supply that will stimulate niche business opportunities that can grow and stimulate technology pull with benefit of real life material product market combinations.

The uniformity of PHA composition and content across groups of organisms in mixed cultures was considered. An activated sludge microbial community, with an average PHA content of 20wt%, was fractioned by Percoll assisted buoyant density separation. The microbial community in the two principal fractions was characterised using amplicon pyrosequencing. While organisms were common to both fractions, the relative abundances of species were found to be different between the two fractions. The average PHA content in one of the fractions was found to be higher (24wt%) than the other (16wt%); separation was considered to be in part driven by the density difference associated with PHA content, but also by other factors such as cell dimension and cellular morphology. But while differences in PHA content were observed, the PHA composition in both fractions was found to be approximately the same (43-44mol% HV), which shows that distinct groups of microbial populations within mixed cultures may generate PHA with similar average copolymer composition.

No abstract