Potencial de reciclagem de lodo de estação de tratamento de água (ETA).

Abstract

The need for drinking water resulting from the population and economic growth of urban centers, increases the production of water treatment plants (WTP) and, consequently, increases the generation of WTP sludge, which is a solid Class II A waste. Brazilian legislation is strict, the incorrect disposal of this waste in the environment is a common practice, which causes major environmental impacts. Aiming to provide recycling alternatives for the sludge from WTP Santa Bárbara, in the city of Pelotas/RS, physical-chemical characterizations were carried out, such as solids, humidity, granulometry, apparent density, Atterberg limits, permeability coefficient, chemical elements, organic matter, loss on ignition, pH and cation exchange capacity of the residue. The generation of the waste was estimated, and its recycling potentials were evaluated, such as its application in soils and incorporation in the manufacture of materials for civil construction. From the characterizations, the possibility of using the WTP sludge in degraded soils, as a heavy metal adsorbent, in agricultural soils, as a fertilizer, and as a covering layer or waterproofing layer in landfills was evaluated. Regarding the manufacture of materials for civil construction, the possibilities of incorporating the residue in cementitious materials, soil-cement bricks and in ceramic materials were analyzed. It can be concluded that the WTP sludge has a cationic exchange capacity and can be used for adsorption of heavy metals in degraded soils and considering that it has several micronutrients necessary for plants, it can be used as a fertilizer for agricultural soils, being necessary practical analysis to make applications feasible. WTP sludge has the potential to replace, in part, fine aggregate, Portland cement, soil and clay in the production of materials for construction, due to their physical and chemical characteristics. However, while recycling of waste with a high impact of contamination is provided, the extraction of non-renewable natural resources is reduced, contributing to the reduction of the environmental impact caused by WTPs.