No abstract

Polyhydroxyalkanoates (PHA) are biodegradable plastics, synthesized by microorganisms. These plastics have similar properties to some of those petroleum-based plastics, so bioplastics are an attractive alternative from the ecological point of view. However, one of the limitations for bioplastics production is their production cost. Currently, the studies are oriented to the reduction of such costs, focusing on the search of cheaper substrates, using in some cases wastes such as industrial or municipal wastewaters or agricultural wastes, among others. In this work polyhydroxyalkanoates production, specifically polyhydroxybutyrate (PHB) was carried out using a secondary activated sludge mixed culture of the wastewater treatment plant "Cerro de la Estrella" and as a substrate using organic wastes leachates, which in addition to being highly polluting due to its high COD concentration, are rich in VFA as well. PHB production was conducted in 2 stages, in the first one an enrichment of PHB producing biomass in a reactor sequencing batch (SBR) with concentrations of 1.8 to 8.35 g TCOD/L was carried out. In the second stage a continuous reactor of 1 L at pH of 7-7.5, environmental temperature, 220 rpm shaking, TRH of 1 day, airflow of 1.7 L/min, was used and PHB production was carried out at 5.6 to 9.09 g TCOD/L. During the enrichment stage and from day 29 of operation the presence of PHB producing bacteria was detected with a maximum PHB accumulation of 56.2% at 6.1 g CODT/L. However during the production stage a destabilization was observed and production decreased to 10%. To recover PHB production levels, reactor operation was returned to sequential mode. Under these conditions there was a recovery in PHB production of 17.