Co-Compost Production from Sewage Sludge Mixed with Vegetable Wastes and Scum

Abstract

The objectives of the study were to determine the physical and chemical characteristics of co-composts and their quality. The co-composts were produced from residue wastes (sewage sludge from domestic wastewater treatment plant, vegetable waste and scum) as an alternative for recycling and reducing solid wastes. The study was consisted of 3 experiments: experiment 1) sewage sludge : vegetable waste, 2) sewage sludge : scum, and 3) sewage sludge : vegetable waste : scum. The total weight of all experiment was 14 kg. The result showed that after composting composts (56 days) had the residual weight of experiment 1, 2, and 3 reduced to 2.47 kg, 11.09 kg, and 3.07 kg, the pH 8.71, 5.44, and 6.91, total organic carbon 26.16 %, 49.40  and 31.84 %, C:N ratio 16.56:1, 88.22:1, and 20.91:1,  respectively. In addition, the highest degradation rate was found in the experiment 1 followed by experiment 3 and 2. The major nutrient and heavy metals (Cu, Cd, and Pb) of the finished compost were observed to meet the compost standard of Land Development Department. The percentage of N, P and K in experiment 1, 2, and 3 were 1.58 - 2.32 - 2.19, 0.56 - 0.98 - 0.50 and 1.52 - 1.96 - 2.00, respectively. The findings suggested that the compost of experiment 1 and 3 might be suitable for soil amendments.