Effect of Composting on Physico-Chemical Properties of Semi-Finished Tannery Sludge

Abstract

Leather processing is one of the hazardous red listed industry which produce large quantity of effluent with high organic load and bulk quantity of solid wastes. The wastes generated from the tannery industry are most concerned and management of this waste should be in ecofriendly manner. Composting is a method of biological decomposition of organic wastes by microorganisms under controlled conditions. In order to optimize the process parameters a windrow method of composting was carried out along with other organic wastes such as poultry waste and coirpith. The results show that electrical conductivity (EC) of the compost was 2.28 dSm-1, pH 7.31 and C/N ratio of 16.97. Concentration of Chromium in the compost was decreased and it was complied with the standards of the Indian limits thus the compost made from the tannery sludge suitable for in Agriculture. The maturity of the composted semi-finished tannery sludge (SFTS) was confirmed through maturity tests such as humification index and qualitative tests including starch iodine and sulphide tests. The germination index for radish seed was 86%, which indicates the absence of toxic compounds in the tannery sludge compost.