Waterworks Sludge: An Underrated Material for Beneficial Reuse in Water and Environmental Engineering: review

Abstract : Waterworks sludge refers to the inevitable suspended and dissolved solids produced during the water purification process when producing tap water where Al-salt and/or Fe-salt are used as coagulant worldwide. Waterworks sludge is dewatered and the resultant cakes have been treated as “waste” for landfill as their major final disposal solution for a long time in practice. As waterworks sludge is the residual of potable water treatment process, it is not harmful and without toxic elements such as heavy metals in most cases in comparison to sewage sludges for instance. Actually, waterworks sludge is an underrated material with huge potential for beneficial reuse as raw material in water and environmental engineering. However, little was significantly progressed on this topic until the last two decades. Research and development (R&D) with special interest and focus on waterworks sludge reuse was conducted in our group in the last 15 years and this paper reports and discusses the main work and its novel application profile. Overall, it is believed that the R&D of waterworks sludge is useful and will help to develop national strategy of the entire waterworks sludge management, allowing its transformation from a “waste” into value-added products, and thus contribute to sustainable development.