Composting of fish wastes in a full‐scale in‐vessel system using different amendments

Abstract

This study examined the effects of two bulking agents (alder and fir), and two amendments (peat moss and vermiculite) on the in‐vessel composting process. The rise in temperature which occurred as composting progressed was accompanied by an increase in ammonia and volatile fatty acid production in the composting bay. This overall pattern was observed in all mixes. All of the compost mixes satisfied the temperature requirements for the destruction of pathogens. In all cases, the concentrations of ammonia and volatile fatty acids increased rapidly and then declined gradually over the monitoring period. The changes in their concentrations over time proved to be a reliable indicator of the progress of an “active”; stage of composting. The disappearance of volatile fatty acids and phenol proved to be a useful indicator of the maturity of fish compost. The fir was a very good bulking agent; its compost became stable earlier than the others. It was shown that nitrogen could be conserved in a compost by additions of a suitable bulking agent, and/or an amendment. In terms of ammonia management, peat moss was found to be a good bulking agent and vermiculite a good amendment.

Key words:

• Fish wastes
• composting
• bulking agents
• amendments
• volatile fatty acids
• ammonia