Composting treatment of fur waste originating from tannery

Abstract

The tanning industry generates effluents with a high contaminant load represented in a considerable amount of liquid, solid, and gaseous waste. Solid waste, such as residual hair, fat, and meat, are dumped directly in landfills, triggering serious environmental problems. The objective of this research was to compost this waste, previously desulfurized, in a mixture with remnants from pruning as a bulking agent. This low-cost strategy may reduce the total amount of waste. A composting pile was created using residual hair and pruning remnants in a proportion of 3:1 (w/w) and then an inoculum was added. The waste degrading process ran for 141 days, followed by a maturation period of 64 days. Throughout the process, the temperature, moisture, pH, and electrical conductivity (EC) were monitored. The highest temperature reached was 69.7°C, which secured good disinfection. The EC was 0.27 dS/cm, having lower values than Spanish regulations, possibly due to the salt removal over the irrigation periods. The organic matter content decreased continuously, to reach an endpoint of 42%; this result agrees with the high organic matter content of the tannery waste and the pruning remnants. Germination index was 43.55%, which indicates the presence of phytotoxic substances. As compared to the initial value (10.73%) there was partial degrading of these substances. The challenge is to improve this parameter by identifying new mixtures and adding efficient microorganisms that help to degrade phytotoxic substances.