An economic assessment of protein recovery from fish meal wastewaters by ultrafiltration

Abstract

The main objective of this work was to evaluate technically and economically the recovery of proteins from fish meal wastewaters using crossflow membrane technology, namely ultrafiltration (UF) and nanof itration (NF). Mackerel processing effluents were pre-treated by microfiltration (MF cartridge battery of 80, 20 and 5 μm) followed by UF (membrane Carbosep M2, 15 kDa MWCO) or NF (membrane Kerasep NanoN01A, 1 kDa MWCO). A suitable membrane treatment for fish meal wastewaters comprised MF pre-treatment followed by UF operating at 4 bar, 4 m/s, natural pH and ambient temperature. Both membranes fully recovered their original permeability through an acidic/basic washing cycle. Ultrafiltration yielded an average permeation flux of 28 L/(M2×h), and 62% protein rejection for a volume reduction factor of 2.3. Economic feasibility of protein recovery from fish meal effluents by UF was evaluated for a production of 544 ton/y of fish meal (66% protein content), yielding a net present worth of US$160×103, internal rate of return of 17% and payback time of 8 years.