Zygmunt Usydus and Piotr J. Bykowski
Sea Fisheries Institute, Kołłątaja 1, 81-332 Gdynia, Poland

Key words: water consumption, chemical characteristics of wastewater, fish.

Abstract.
The quality of wastewater produced by the fish processing industry depends largely on the water management conducted by individual production plants. The results of studies for the past 25 years indicate that there has been a decrease in water consumption per 1 ton of final product, and at the same time, an increase in the values of contamination parameters of wastewater produced. Contamination loads in wastewater remain unchanged. Wastewater with the highest levels of contamination parameters is generated by the plants producing fish meal, fish oils and marinated fish products. During the manufacturing of these products, large amounts of proteins and fats end up in wastewater, and contribute to the level of oxygen demand. The main aim of wastewater treatment in the fish processing industry is to maximize the removal of contaminants and to use the removed substances for fodder, fertilizers or other technical purposes.