Mixed-culture biotechnological processes for lipid-rich effluents valorization

Abstract

Lipid-rich effluents have great potential to be transformed into precursors for the obtainment of bioenergy and biomaterials, mainly triacylglycerides (TAGs) and polyhydroxyalkanoates (PHAs), using different biotechnologies. However, current valorization processes cannot compete with conventional petroleum-based ones and more research is needed in this field. The development of cost-effective methods requires the use of residual substrates and simplified engineering designs based on the use of mixed microbial cultures (MMCs) that do not require sterile conditions. In this thesis, it was explored the simplification of the typical valorization train used for residual effluents bioconversion into TAGs and/or PHAs. Firstly, it was reduced from three to two units avoiding substrate pretreatment, and later, it was evaluated the feasibility of performing the whole process in a sole bioreactor. Also, it was tended to define the most suitable selective pressures to engineer the ecosystem in order to maintain a specific culture functionality (TAGs and/of PHAs) production. Moreover, it was evaluated the feasibility of implementing the process in saline environments such as fish-canneries, where wastewater streams containing high fat, oil and grease concentrations are generated.