Solvent extraction of salt from wastewater generated at a fish processing industry was investigated and successfully carried out. 33% of salt was precipitated at the optimal operating conditions of 0 °C, 100% (v/v) ethanol added to the wastewater and at a settling time of 30 min. Amount of salt precipitated could be increased by several extraction stages, each followed by ethanol distillation. Salt contained in the supernatant allows avoiding the azeotrope formed by water and ethanol, making the recovery of pure ethanol feasible which could be recycled in the next precipitation stage. It can be concluded that salt precipitation from the wastewater by ethanol allows the recovery of the organic load – valuable proteins, peptides and amino acids – and salt dissolved in that residual water. Ethanol can be considered the driving factor for salt precipitation while the low temperature helps avoiding protein denaturation and precipitation. Changes in pH did not exert any effect on salt precipitation.
Results obtained by our research allowed assessing the feasibility of codfish salting processing wastewater upgrading by amino acids and proteins recovery after salt removing. Valorisation of that liquid waste could contribute to codfish salting industry sustainability, through reduction of costly disposal treatments and creation of economical value from a costless feed.