Clean technology in fish processing industries

Abstract

The effects of fish-meal manufacturing on the seawater has reached troublesome levels in Chile, particularly in the VIIIth Region where most of the fish-meal industries are located. The scope of this work was to study the process, classify the pollutant streams, and pinpoint those steps that could be improved in order to reduce their contaminant effect, while salvaging reusable organic matter. As a result, we propose the introduction of a new step in the fish reduction process that involves recirculation of the pumping water used to unload the fish, screening of coarse organic matter, flocculation of soluble proteins in the recirculate and its separation by centrifugation, and the incorporation of both coarse and flocculated material to the reduction process. This reduces by 91.6% the estimated chemical oxygen demand (COD) value of a ton of processed fish and increases by 7% the industries' productivity. Reduction of the remnant organic load can be achieved by in-series anaerobic and aerobic degradation. The effect of the latter treatment reduces by an additional 5.6% the COD value. Marginal profits are higher than the treatment cost for high technology plants, as shown by a return on investment of 52.89% after a 5 year period.