Alternatives for the environmentally appropriate disposal of sludge from water treatment plants with an emphasis on the Brazilian reality (Atena Editora)

Abstract

The management and disposal of sludge generated in water treatment plants in Brazil is still a major problem for water utilities. In many cases, sludge is discarded in natura in water bodies, causing several environmental impacts, in addition to not meeting the demands of current legislation. The present study aims to carry out a bibliographic review on sludge from water treatment plants (WTP), including aspects related to the negative consequences of its improper disposal. On the other hand, in addition to presenting environmentally appropriate alternatives for this final destination, it discusses possible ways of using LETA with a focus on the circular economy, that is, as an input for other activities. The evaluated publications were segregated by sludge utilization typology, identifying the strengths and weaknesses (critical points) for each typology. After compiling the collected data, one can infer the feasibility of using or incorporating LETA for different uses, as long as it is inserted in small amounts. In the cement and concrete manufacturing process, for example, additions greater than 5% must be avoided, as the workability and some mechanical properties are impaired to the point of making the final product unfeasible. Its use in agriculture can be done in conjunction with sewage treatment plant sludge (LETE). In the vast majority of studies surveyed, it is indicated that the addition of WTP sludge as an input reduces the consumption and exploitation of natural raw materials, mitigating the various negative environmental impacts arising from improper disposal. However, whatever the type of reuse, more specific studies are required to establish a reuse methodology with the necessary reliability for the process. In addition, potential risks to human health due to frequent handling must be analyzed.