Environmentally friendly characterization and disposal of sludge generated by water treatment plants

Abstract

Sludge generated by water treatment plants is the waste formed during the process of transforming raw water into drinking water through coagulation, flocculation, decantation and filtration processes. This waste with toxic characteristics, therefore, has its destination compatible with the guidelines of PNRS - Law 12.305 / 2010, prioritizing the possibility of reduction, reuse and recycling. Thus, this paper aims to review the sludge generated by water treatment plants, and to suggest alternatives for reusing this waste in an environmentally sound manner. This work was built through bibliographic reviews, aiming to describe the problem of sludge and ETA and to suggest environmentally correct means for disposal of this waste. Among the alternatives, we can highlight the use of sludge in agricultural soils, whose improvements are structural soil; pH adjustment; addition of trace minerals; increased water retention capacity and improved soil aeration conditions. In seedling production, it can contribute to the supply of nutrients and organic matter to the plant. Other destinations may still be adopted, such as production of ceramics released into the domestic sewage system or landfill. In view of the restrictions in the legislation for the disposal of waste water from ETAs into bodies of water, the volume of water lost and the environmental impacts associated with this practice, there is a growing need to provide appropriate disposal or productive use of such waste, also minimizing the amount of byproduct generated. Thus, it is necessary to study the proper final disposal of this waste in order to contribute to the minimization of environmental impacts by preventing sludge from being released in natura to water bodies.