Turning fish canning wastewater into resources: Effluents and operational conditions selection for volatile fatty acids production

The potential of three fish canning wastewaters to produce volatile fatty acids (VFA) was evaluated using a stepwise procedure at laboratory scale. Batch tests (0.5 L), at different food to microorganism ratios (F/M), presented tuna and mussel cooking wastewaters as the highest yield substrates (60 % and 80 %, respectively). F/ M ratios tested did not significantly influence the yield or the VFA spectrum. Continuous reactors (5 L) were operated with these two wastewaters at different hydraulic retention times (HRT). The shortest HRT studied (2 d) favoured the yield and the production of longer-chain VFA (butyric and valeric acids) in tuna wastewater. However, for mussel wastewater, the yield decreased 2-fold and the production of short-chain VFA (acetic acid) was favoured. This study offers an overview of the best fish canning wastewater, from a point of view of maximum VFA yield, and its optimal operational conditions for VFA production.