Potential and Weaknesses of Incorporating Water Treatment Plant Sludge Into Concrete

Objective: The aim of this study was to identify the potential and weaknesses of incorporating sludge from water treatment plants, wet or calcined, in the manufacture of conventional or structural concrete, based on a systematic review of the literature. Theoretical Reference: The process of potabilizing water for human supply generates waste called water treatment plant sludge (WTS), which is currently still disposed of inappropriately, but which, due to its characteristics, is viable for use as a material for civil construction. Method: The Prisma methodology was used to develop this systematic review. Searches were carried out in the Scopus and Web of Science databases using the keywords: sludge, cement composite, concrete, drinking water and water treatment. The categorization of the results included elements about the waste, the technologies adopted for its beneficial use and the potential of incorporating LETA into concrete. Results and Discussion: LETA is an advantageous alternative for partially replacing fine aggregate in concrete production, due to its specific properties. It is important that the characterization of LETAs for use in concrete includes parameters such as pH, humidity, organic matter content and the particle size of the waste. There is evidence that LETAs can replace up to 10% of fine aggregate in concrete production, but with a loss of mechanical strength. Research implications: It was possible to verify the technical feasibility of incorporating LETA into concrete production to replace fine aggregate. However, there is still a research gap regarding the environmental and economic evaluation of this beneficial use and these aspects are crucial for the effective use of concrete with LETA to meet market demands. Originality/Value: The beneficial use of LETAs makes it possible to incorporate the principles of the circular economy into water purification plants. This unprecedented systematic review of the literature on the incorporation of LETA in the manufacture of concrete highlights the paths already taken and the need for further studies on the subject.