Comparação do lodo do tratamento de água gerado pelo uso de coagulante orgânico e inorgânico

Abstract

In the water treatment process, the Water Treatment Plants (WTP) generate a byproduct - the sludge. This solid waste is generated mainly in the decantation units and, to a lesser extent, in the water filtration stage. It is generally discharged into the environment without prior treatment, especially into bodies of water, and can cause pollution of water sources. Aiming to minimize the impact caused by the disposal of this waste into the environment, natural coagulants have been a viable alternative to replace chemical coagulants, especially aluminum sulfate, because besides being biodegradable, the natural coagulant produces less sludge and with lower metal content. The objective of this study was to compare the sludge resulting from the treatment of the water collected from the Poxim WTP with the use of a chemical coagulant based on aluminum sulfate and a natural coagulant from Moringa oleifera seed. The experiments were performed from five collections of water from the Poxim river. The sludge was analyzed and compared for the solid parameters: total solids, total suspended solids and settleable solids. For the raw water, the quantification of total and total suspended solids was performed, besides the analysis of physical-chemical parameters such as: temperature, pH, apparent and true color, turbidity and conductivity. The analysis of the physicochemical parameters of the raw water, as well as the determination of total and total suspended solids were developed based on American Public Health Association (APHA). The methodological reference used for the quantification of settleable solids was the Norma Técnica Interna SABESP NTS 013, through the use of Imhoff cone. As results, the study showed that there were statistically significant differences between the concentrations of total and total suspended solids of the sludge produced with the use of aluminum sulfate and the sludge generated with the use of Moringa oleifera seeds as coagulant. However, with regard to settleable solids, the sludge presented statistically equal concentrations at the 95% significance level. The sludge generated by the use of moringa, besides being biodegradable and non-toxic, showed lower total solids content, showing itself to be a viable alternative to replace or reduce the use of aluminum sulfate.