44D-1 |
Studies on the biodegradation of fisheries wastes by a vermicomposting process |
A. M. MARTIN, Dept. of Biochemistry, Memorial Univ. of Newfoundland, St. John's, NF A1B 3X9, Canada, S. Decker, Environmental Science Program, Memorial Univ. of Newfoundland, St. John's, NF A1B 3X9, Canada, and R. J. Helleur, Dept. of Chemistry, Memorial Univ. of Newfoundland, St. John's, NF A1B 3X9, Canada. JUSTIFICATION: Food processing wastes are characterized by high organic matter content and values of oxygen demand. Composting is one of the biological waste treatment alternatives to disposal of these byproducts. In wastes from animal origin, nitrogen is the main nutrient contributed to the compost mixture, however proteins and derived nitrogenous compounds decompose to nitrate, nitrite, and finally to ammonia, which will tend to escape as a gas from the process. Therefore, one way to reduce nitrogen loss from the compost mixture is to add a co-substrate with ammonia adsorption characteristics. Another possibility for enhancing composting is by using earthworms (vermicomposting). This process has been applied mostly to the biodegradation of agricultural food wastes, and few studies have been conducted on the use of earthworms in the composting of wastes of animal origin. OBJECTIVES: The main objectives were to study the vermicomposting of fisheries wastes biomass and to evaluate if this process is effective in the biodegradation of proteinaceous compounds of animal origin. METHODS: Composting of fish offal was conducted in 500 mL plastic containers. The temperature and moisture content were controlled at 25 ± 2°C and approximately 80%, respectively. The total duration of the experiments were twelve weeks. The progress of the processes was evaluated by chemical analyses of the composting biomass. To prevent the loss of ammonia from the composting mixture, the fish offal was mixed with peat, which was previously found to be among the best adsorbents for the retention of ammonia. Standard analytical procedures were employed to determine the chemical composition of the mixture. All experiments were conducted in triplicate, and the results were analyzed statistically. RESULTS: High concentrations of ammonia, a product of protein degradation, exerted inhibitory effects on earthworm viability. The presence of an ammonia adsorbent in the compost contributed to reducing this problem, resulting in a product with a nitrogen content of approximately 2% (dry weight). It was found that the non-proteinaceous co-substrate for the composting process should account for at least 85% of the total dry weight of the mixture for an appropriate operation of the process. SIGNIFICANCE: The results show that vermicomposting has potential for use in the biodegradation of food processing wastes of animal origin.
Session 44D, International
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