The reuse of spent bleaching earth for the stabilisation / solidification of mixed waste streams

A low-cost adsorbent prepared from an existing solid industrial waste is proposed for the pre-adsorption of organic components in mixed waste streams prior to treatment by cement-based stabilisation / solidification. A feasibility study compares the performance of activated spent bleaching earth with commercial powdered activated carbon in cement / waste / adsorbent blends. The waste clay, added as 10% w/w of the total mix, was found to reduce leachable TOC from four synthetic mixed wastes by up to 37% w/w and increase 28 day strengths by 240 - 1300 % as a result of pozzolanic activity. Application of the adsorbent for the treatment of such wastes could offer significant cost benefits over the use of conventional industrial adsorbents and provide a novel waste minimisation opportunity for a material which currently presents considerable disposal problems.