ACHIEVING CLEAN TECHNOLOGY IN THE FISH-MEAL INDUSTRY BY ADDITION OF ANEW PROCESS STEP

Fish-meal processing plants use large volumes of seawater to unload th e fish from ships. Water to fish ratios range from 5 to 10 (m(3) tonne (-1)), producing an effluent high in chemical oxygen demand (GOD) load , which is discharged to the sea. Alternative treatments were studied from economic and environmental aspects. The selected treatment involv ed two sequential steps: recycling of water during unloading and salva ging of reusable organic matter by chemical coagulation of soluble pro teins with FeCl3 followed by centrifugal separation. The recovered slu dge was incorporated into the fish-meal process. Technical feasibility and cost implementation at industrial-scale were assessed. Results ob tained at one plant demonstrated overall COD removal efficiencies of 9 3% for the clarified effluent (91% for proteins and 93% for fats and o il). Incorporation of the precipitated organic matter into the process increased productivity by approximately 7%.