AVALIAÇÃO DE SISTEMA SUBSTRATO-PLANTA CONTENDO LODO DE ESTAÇÃO DE TRATAMENTO DE EFLUENTES PROVENIENTE DE INDÚSTRIA DE TINTA

The latex paint industry uses drinkable water on a large scale in its process. After used, it goes to effluent treatment plants (ETP), generating a sludge as a by-product. Currently, this residual sludge is disposed in co-processing furnaces, which creates a problem due to the high costs associated with this process This study aims to evaluate the viability of using the ETP sludge from a local latex paint industry as a substrate in the farming of Lobularia maritime. In total, five treatments composed by different amounts of sludge and substrate were performed, one being the control, containing 0% of sludge, and the others in the proportions of 10%, 20%, 30%, 40% (substitution in volume of substrate for sludge). The sludge samples and the five treatments were characterized by pH, electrical conductivity (EC), total content of soluble salts (TCSS), bulk and dry density, moisture content and particle size distribution analyses.  In addition to the previous mentioned analyses, for the sludge samples, X-ray fluorescence analyses (XRF), thermo-gravimetric analysis (TGA/DTG) and specific mass determination were also performed, and for the treatments studied, analyses of porosity, water retention capacity and plant growth were carried out. In all treatments evaluated, the results of EC and pH were within the parameters established by the literature. The chemical analysis showed that the sludge is composed mainly of calcium (Ca), titanium (Ti), silicon (Si), aluminum (Al) and iron (Fe). As for the physical characterization, it was found that the incorporation of the residue results in an increase in density and a decrease in moisture content and in the average diameter of the system particles, negatively affecting the water retention capacity, total porosity and, possibly, the amount of micropores. All treatments showed plantular development, concluding that, when used in low proportions (up to 10% v:v), the sludge has potential use as a partial substitute material for substrate to produce seedlings.