Seafood processing wastewater contains elevated concentrations of protein-enriched biomass, which is frequently lost by discharging or landfilling process sludge. Recovery of organics by coagulation and dissolved air flotation entails use of non-food grade flocculants, rendering the resulting sludge unusable as a food component. The inclusion of seaweed-derived alginate and carrageenan as food-grade flocculants in this process was demonstrated to efficiently recover proteins from shrimp boiling and peeling wastewater.

The modified flocculation-dissolved air flotation scheme reduced the protein content of influent shrimp boiling The process recovers waste nutrients from shrimp processing water. Source: jekjob/Shutterstock.comThe process recovers waste nutrients from shrimp processing water. Source: jekjob/Shutterstock.comwastewater, initially 12.4 g/l, and shrimp peeling wastewater, initially 1.4 g/l, by up to 76% and 85%, respectively. Proteins in boiling and peeling wastewaters were concentrated up to seven and 29 times, respectively, yielding a protein-enriched biomass.

Spray-dried and recovered biomass contained up to 61% proteins; up to 47% of the amino acid constituents were identified as essential. The flocculation-dissolved air flotation scheme developed by researchers from Chalmers University of Technology (Sweden), Technical University of Denmark, Räkor & Laxgrossisten AB (Sweden) and Bio-Aqua A/S (Denmark) can be applied to nutrient recovery from seafood processing wastes.

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