BIODEGRADABILITY AND TOXICITY IN THE ANAEROBIC TREATMENT OF FISH CANNING WASTEWATERS

Sea fish canning industries produce effluents with a high load of organic matter. High concentrations of salts and possible production of H2S and NH4+ from the degradation of sulphates and proteins respectively, can cause toxicity/inhibition problems during the treatment of these effluents by anaerobic digestion. Biodegradability, toxicity/inhibition, operational temperatures, and the options of treating several effluents separately or jointly were studied. Anaerobic biodegradability reached up to 90% of soluble COD. Despite the high levels of sodium, ammonia and sulphide present, the results obtained allow us to predict a successful operation when adequate conditions are established. In order to gather more information as to the design of an industrial plant, complementary studies of pretreatment of effluents from fish meal factories and the use of high rate anaerobic digesters are proposed.