Reuse of Wastewater Sludge in Manufacturing Non-Conventional Construction Materals - An Innovative Approach to Ultimate Sludge Disposal

Abstract

The increased requirements for the treatment of wastewater, coupled with industrial growth, have created a need to treat and dispose of an over-proportional sludge volume. At the same time increasingly stringent regulations have resulted in limitations on the ultimate sludge disposal options. In highly urbanized municipalities, scarcity of landfill sites and increasing environmental awareness pose major public concern on the disposal of sludge. This situation has prompted the interest in recycling and reuse of sludge into building and construction materials as means of alleviating sludge disposal problems. This paper presents the results of the use of wastewater sludge to produce lightweight aggregates and cementitious binder as non-conventional construction materials. Lightweight coarse aggregates were produced from the incineration of sludge-clay mixture. Test results of porosity, specific gravity, bulk density, ten percent fines, water absorption and concrete strength, indicate that clay-blended sludge could be used to produce lightweight aggregates. The feasibility of using dried sludge mixed with lime as a cementitious binder after incineration was also studied. Evaluation of the mortar cube strengths shows that it is possible to produce masonry binder from sludge that will satisfy the strength requirements in the ASTM standard for masonry cement.