Use of tannery sludge ash as filler in waterproofing membranes

Tannery effluent treatment plant sludge is a by-product of leather-making industry in which chrome compounds are the most common used materials. The aim of this work was to investigate the effects and feasibility in the use of tannery sludge ash as a partial or totally replacement of usual mineral filler such as CaCO3 in manufacture of waterproofing membranes. The effects of sludge ash on the morphology and mechanical properties of membranes were investigated. Leaching tests were carried out in order to guarantee that the fulfillment of "filler function" was done in respect with environmental criteria. The results in terms of performances and leaching tests indicate that tannery sludge ash could be used as total replacement of CaCO3 for waterproofing membranes. This work has to be intended as the first step of a study whose final goal is to find an effective, industrially applicable, way to improve recycling capabilities of tannery effluent treatment plant sludge in systems like roofing and waterproofing membranes thus solving an economical and environmental problem.