Compost detoxification of vegetable tannery sludge

The disposal problem represented by vegetable-tannery sludge is of great and ever-increasing concern in Italy. Such sludge is of a highly polluting nature and therefore, requires a reliable and safe treatment to make it harmless before release into the environment. Vegetable-tannery sludge contains some very toxic compounds, mainly polyphenols (i.e. tannins) and sulphides, that are hazardous to biological systems. This paper deals with experiments evaluating the feasibility of vegetable-tannery sludge management and recycling by an integrated composting process. Static windrow technique with forced air and temperature feedback has been adopted for composting a mixture of vegetable-tannery sludge and organic biodegradable fraction of municipal solid waste (MSW) as bulking agent. Physico-chemical, microbiological and phytotoxicological aspects of this compost production from vegetable-tannery sludge are here emphasized along with some technological details.