Composting sludge from seafood processing wastewater treatment system with different bulking agents

Abstract

This study composted sludge from the seafood processing wastewater treatment system mixed with straw and rice husks. Waste sludge with high moisture content, low C/N ratio and porosity, was mixed with straw and rice husks to create a moisture mixture of 63-65 %, C/N ratio of 29-30, and porosity suitable for aerobic composting. Three composting experiments with different mixing ratios by mass of the ingredients, BR (Sludge: straw = 1: 0.3), BV (Sludge: rice husks = 1: 0.32) and BH (Sludge: straw: rice husks = 1: 0.18: 0.15), were carried out at the scale of composting bins (volume 0.11 m³), with mechanical aeration and periodic turning. Process parameters such as temperature, humidity, C/N ratio, pH, and organic matter content were monitored. The compost product was evaluated by measuring the germination ability of seeds. The two treatments BR and BV reached a maximum temperature below 55^oC. The BH treatment reached the thermophilic phase on the 6th day of the process, the highest maximum temperature (57^oC) and the maintenance period above 55^oC was 3 days. The organic matter content decreased by 54.1%, the germination coefficient GI: 84.7%; showing that this treatment was the best organic matter decomposition process. The study showed that through the selection of materials and mixing ratio, the quality of the compost product can be controlled.