PRODUCTION OF COMPOSTING AND SILAGE AS A SUSTAINABLE MANAGEMENT OF FISH WASTE

Abstract

The incorrect disposal of fish waste can cause major environmental, health and economic disorders. In this context, the production of compost and silage of these residues can transform them into organic fertilizer and food of high biological value. Therefore, the present study aimed to evaluate and characterize the production of organic compost and acid silage from fish waste collected at the Modern Manaus fair, Manaus, AM. To evaluate the composting production, a completely randomized design with three treatments and three replications was adopted. The treatments were: composting of fish waste and wood shavings; composting fish waste and grass clippings and composting fish waste and tree trimming. The composting production process was monitored for 40 days, until temperature stability. The evaluated parameters were: temperature, humidity, hydrogenion potential (pH), ash, total organic matter, total organic carbon, total nitrogen, C/N ratio and mineralization index. For the preparation of silages, the residues were submitted to a cleaning process, which consisted of cooking at a temperature of 100 ºC, for a period of 45 minutes. Three silages were prepared, in triplicate; silage formulated with 6% glacial acetic acid; silage formulated with 5% citric acid and 1% glacial acetic acid and silage formulated with 5% fumaric acid and 1% glacial acetic acid. The ensiling process was carried out at room temperature and the hydrolysis period was monitored with daily measurements of pH and temperature until parameters stabilized. The physical-chemical composition of the composts and silages were submitted to analysis of homogeneity and normality to verify if the averages presented normal distribution and later the analysis of variance (ANOVA) and the Turkey test were applied at a significance level of 5% (p < 0.05). The results of the physical-chemical parameters evaluated at the end of the composting process serve to evaluate the effectiveness of the process. Thus, noting that the composting method is a viable alternative for the use of fish waste, even though the results of the present study have shown values for moisture and C/N ratio higher than those recommended by Brazilian legislation for the use of organic fertilizers for both compounds, thus, suggesting the use of a higher nitrogen source for the elaboration of organic compounds in the experimental conditions of the present study. The elaboration of acid silage from fish residues proved to be a viable alternative to add value to fish residues discarded at fairs and fishmongers, as well as to contribute to the reduction of the emission of pollutants to the environment. In addition, serve as a subsidy in the production of low-cost feed for aquaculture.