Análise da toxicidade do lixiviado gerado em uma célula do aterro sanitário em Campina Grande-PB.

Abstract

Sanitary landfilling is the most widely used final disposal technique for municipal solid waste in the world. However, due to the complexity of the biological degradation process inside the waste mass, the leachate liquid are generated. The leachate requires special attention, because it is a toxic, heterogeneous effluent with a very varied and complex composition; can cause promote toxicity to health public and the environment. In this context, this work aimed to analyze the toxic potential of leachate generated in a landfill cell in Campina Grande – State of Paraiba, Brazil. The experiment consisted of collecting samples of fresh leachate (biweekly from June to November of 2016) in a well that received all the liquid generated by the landfill cell studied, from the landfill of Campina Grande. After collection, the leachate was characterized by physical-chemical (pH, total alkalinity, volatile fatty acids, chlorides, chemical oxygen demand, total ammonia nitrogen and heavy metals) and toxicological (phytotoxicity) analyses. In addition, the correlations between these parameters were verified. The results registered that in acidic conditions of pH, the leachate presented high concentrations of volatile fatty acids, biochemical demand of oxygen and metals (especially iron, manganese and chromium). These were the main factors causing phytotoxicity of tomato (Solanum lycopersicum) and cabbage (Brassica oleraceae) seeds. However, when the pH of the leachate tended to be between neutral and basic, the concentrations of the analyzed metals decreased, reducing the toxicity potential of the leachate in relation to the metals. Even so, during this period, the highest levels of total ammoniacal nitrogen were obtained. Because nitrogen in the form of ammonium ion prevailed in the leachate, this component probably did not infer toxicity to plant seeds. It can be concluded that the leachate presents a higher phytotoxic potential in the acid degradation phase. With the evolution of the biodegradation process of the residues deposited in cell studied, despite the high levels of ammoniacal nitrogen measured, the phytotoxicity tests evidenced a leachate with a lower toxic load.