Bioconversion of Organic Pollutants in Fish-Canning Wastewater into Volatile Fatty Acids and Polyhydroxyalkanoate

Abstract

The wastewater from the cookers of a tuna-canning plant was used as feedstock for the process. It was acidified in a continuous stirred tank reactor (CSTR) of 1.5 L to produce a mixture of volatile fatty acids (VFAs). The effluent contained 28.3 ± 8.7 g CODS/L and 25.0 ± 4.6 g CODVFA/L, 4.4 ± 1.6 g NH4+/L, and 10.9 ± 4.0 g Na+/L, which corresponds to about 28 g NaCl/L approximately. This was used to feed a PHA production system. The enriched MMC presented a capacity to accumulate PHAs from the fermented tuna wastewater. The maximum PHA content of the biomass in the fed-batch (8.35 wt% PHA) seemed very low, possibly due to the variable salinity (from 2.2 up to 12.3 g NaCl/L) and the presence of ammonium (which promoted the biomass growth). The batch assay showed a PHA accumulation of 5.70 wt% PHA, but this is a much better result if the productivity of the reactor is taken into account. The fed-batch reactor had a productivity of 10.3 mg PHA/(L h), while the batch value was about five times higher (55.4 mg PHA/(L h)). At the sight of the results, it can be seen that the acidification of fish-canning wastewater is possible even at high saline concentrations (27.7 g NaCl/L). On the other hand, the enrichment and accumulation results show us promising news and which direction has to be followed: PHAs can be obtained from challenging substrates, and the feeding mode during the accumulation stage has an important role to play when it comes to inhibition.

Diversidad Microbiana Presente en Agua Residual Proveniente De Industria Atunera

“…Más allá de la generación de empleo y el crecimiento económico relacionado con las industrias de conservas de pescado y marinas, este sector produce grandes cantidades de desechos que necesitan un mayor tratamiento. Estos efluentes se caracterizan principalmente por flujos abundantes con altas cargas orgánicas además de altas concentraciones salinas (Palmeiro-s & Campos, 2021), siendo difícil gestionar los efluentes de las conservas de pescado, ya que son estacionales con una alta fluctuación de materia orgánica.…”