Constructive approaches towards water treatment works sludge management : an international review of beneficial re-uses

Till date, virtually all known drinking water processing systems generate an enormous amount of residual sludge, and what else to do with this rapidly increasing 'waste' stream in an economic and environmentally sustainable manner remains a significant environmental issue. Perhaps, the realization of this fact has led to series of concerted efforts aimed at beneficial re-uses in an effort to close the loop between efficient water treatment and sustainable sludge management. This paper therefore presents a comprehensive review of available literature on attempts at beneficial reuses of water treatment plant sludge, in an effort to provide a compendium of recent and past developments, and update our current state of knowledge. Four broad categories of uses, which included over eleven possible ways in which waterworks sludges can be reused were identified and examined. Obvious advantages of such reuse options were highlighted and knowledge gaps identified. Future issues that will assist in the development of sustainable waterworks sludge management options with a multi-prong approach were equally discussed.