Evaluation of coagulation/flocculation process in the landfill leachate treatment at the Municipal Wastewater Treatment Plant

The combined treatment of leachate from urban solid waste landfills in a Municipal Wastewater Treatment Plant (MWTP) minimizes the implementation and operation costs of a landfill. This work investigated the combined treatment of the leachate from Morro do Céu Landfill in Niterói, RJ and sewage samples from Icaraí MWTP with different proportions (0, 0.5, 2.0 and 5.0 %). This MWTP features a physical chemical treatment followed by expulsion through a submarine emissary, and so the physical chemical treatment was simulated. The coagulants used were ferric chloride, aluminum sulfate, Tanfloc SG, Tanfloc SL and PanflocTM Hiper Plus in different concentrations (20, 40 and 60 mg L-1). During testing, polyelectrolytes in concentrations of 0.5 and 1.0 mg L-1 were added in some samples to stimulate flocculation. The statistical analysis of COD removals showed that Tanfloc SG achieved better results than the other coagulants in all conditions studied, without requiring the addition of polyelectrolytes. Toxicity tests were performed on the raw sewage with a mixture of 5.0 % of landfill leachate and in the mixture treated with Tanfloc SG. The results indicated that the toxicity of the samples is lower than the limit established by current Rio de Janeiro State legislation (NT-213, INEA).