In the production of marinated herring, nearly one ton of acidic saline marinade is produced per 1.5 tons herring fillet. This spent marinade contains highly valuable compounds such as proteins and amino acids. Membranes are suited to recover these substances. In this work, six membrane stages are employed: microfiltration (MF) (0.2 mu m), ultrafiltration (UP) (50, 20, 10 and 1 kDa) and nanofiltration (NF). The most promising stages are 50 kDa UP and NF based on SDS-PAGE analyses and total amino acid concentration. The 50 kDa stage produces a protein concentrate (>17 kDa). NF produces a retentate containing sugars, amino acids and smaller peptides and a NF permeate containing salt and acetic acid ready for reuse. 42% of the spent marinade is recovered to substitute fresh water and chemicals. The waste water amount is reduced 62.5%. Proteins are concentrated 30 times, while amino acids and smaller peptides are concentrated 11 times. (C) 2015 Elsevier Ltd. All rights reserved.