The new generation of wastewater treatment facilities should include the recovery of resources as value added products. In this sense, this theme proposes the production of biopolymers in parallel to the treatment of wastewater by biological means. One of the most promising biodegradable materials to emerge in recent times is the family of polyhydroxyalkanoate (PHA) polymers produced by almost all bacteria. PHAs are synthesized and accumulated as intracellular granules that serve as an energy and carbon reserve when bacteria becomes limited for an essential nutrient but, are exposed to an excess of carbon. Among PHAs, extracellular polymeric substances (EPSs), other type of microbial biopolymers, are produced and used by microorganisms as protecting agents against desiccation and predation and as building material in biofilm formation.
The prevailing technology for PHA/EPS production is through the use of pure bacterial cultures requiring asepsis and using pure concentrated substrates. Although currently being produced commercially, the product is more expensive than available fossil-fuel based polymers and therefore, is still mostly regarded as a fine rather than a commodity polymer. Mixed bacterial culture production has recently started to attract a lot of attention. It has the potential to produce large amounts of EPS/PHAs at lower costs due to almost no need of sterility, simple equipment and control requirements and the ability of utilise a wide range of cheap substrates, including industrial and agricultural wastes.
In this sense, our research group aims to study the design and optimal dynamic operation (i. e. nutrient conditions, aeration mode, carbon source concentration and type, temperature and pH) of a mixed culture process for the efficient production of EPS/PHA with tailor-made molecular properties. Also we are interested in optimising the biopolymers extration.