May 2013. Vol. 3, No. 3 ISSN2305-8269 International Journal of Engineering and Applied Sciences © 2012 EAAS & ARF. All rights reserved www.eaas-journal.org 69 CHARACTERISATION AND PERFORMANCE EVALUATION OF WATER WORKS SLUDGE AS BRICKS MATERIAL Anyakora Nkolika Victoria Chemical Engineering Department, Ahmadu Bello University, Zaria, Nigeria. (Email: vicanyakora@yahoo.com) ABSTRACT Sludge collected from Lower Usuma Dam Water Treatment Plant (LUDWTP), Abuja, Nigeria was investigated for use as brick material. The reuse of sludge as brick material is a long-term approach to sludge disposal for economic and environmental sustainability. Characterisation and laboratory trials demonstrated that LUDWTP sludge could be used as a colorant and clay supplement in brick making. Five different mixing ratios of sludge at 0, 5, 10, 15 and 20 per cent of the total weight of sludge-clay mixtures were studied. Each batch of hand-mould produced green bricks was fired in a heat controlled furnace at elevated temperatures of 850 o C, 900 o C, 950 o C, 1000 o C, and 1050 o C respectively. The physical, mechanical and chemical properties of the produced sludge-clay burnt bricks (SCBB) were determined and evaluated according to Nigerian Standard Specifications (NIS 74:1976) and British Standard specifications (BS 3921: 1985) while various Indian Standard Code of Specification for burnt clay bricks were used for the performance evaluation as engineering materials. The results showed that LUDWTP sludge can be used to produce good quality brick for various engineering applications in construction and building. Also, the results of tests indicated that the firing temperature and the sludge proportion were the two key factors that determine the quality of bricks. Increasing the sludge content results in decreased compressive strength, decreased density and increased water absorption. The result also showed that increasing the sludge content improved workability and physical appearance (colour) of sludge –clay burnt bricks. Toxicity Characteristic Leaching Procedure (TCLP) tests of the sludge-brick showed that the metal leaching level is within the acceptable limits of Nigerian Environmental Standards and Regulations Enforcement Agency (NESREA) and US Environmental protection Agency (USEPA) limits. Keywords: Characterisation; performance; water works sludge; evaluation; building material. 1. INTRODUCTION Potable water treatment facilities remove impurities from raw water sources using various water treatment chemicals. The by-product from the purification process is called water treatment sludge. The composition and properties of water treatment sludge depends on the quality of raw water and the type of treatment chemical used in the treatment processes. Water treatment plants produce large quantities of sludge as a result of treatment processes of raw water such as coagulation, flocculation and filtration. Ultimate disposal of this sludge include land application, disposal in a sanitary sewer, disposal in surface waters and deep well injection of brine (Syed, 2000). The handling and disposal of sludge is one of the most significant challenges in water works management. In many countries, sludge is a serious problem due to its high treatment costs and the risks to environment and human health. The sludge presents increasingly difficult problem to cities of all sizes because of the scarcity of suitable disposal sites, increasing labor costs, and environmental concerns. Some researchers have linked aluminium‟s contributory influence to occurrence of Alzheimer‟s, children mental retardation, and the common effects of heavy metals accumulation (Mohammed et al, 2008). Presently in Nigeria, most water works dispose sludge by returning it to water course or stock- pile in or around the treatment plants without further treatment which is against the local and International good practices for environmental sustainability.