Effects of inoculation with halotolerant bacteria on composting of saline fish sludge

Abstract

The extensive use of salt in the food industry, especially in sea fishing, generates saline waste, such as sludge from salted fish effluent stations. Improper waste disposal contributes to significant environmental problems, such as inhibiting the natural microbiota and affecting the biogeochemical cycle. The study suggests using composting, with the addition of halotolerant bacteria, to address the issues related to the treatment of sludge from saltwater aquaculture to make the process more efficient and viable. The study's objectives included the application of halotolerant bacteria in the treatment of saline waste via controlled composting, its feasibility for treating this waste, and the compost quality after the composting process. The results indicated a reduction in electrical conductivity, maintenance of pH within legal standards, an insignificant decrease in carbon content, and adequate humidity in the treatments with the inoculums. Despite the drop in nitrogen levels due to denitrification caused by bacteria, mineral matter increased due to microbial action. The saline fish sludge obtained better results with the addition of inoculants, indicating improvements such as the introduction of nitrogen-rich waste, modifications to the volume/structuring material, and a more extended composting period. It is important to note that the results met the standards of Brazilian legislation despite the observations made.