Sludge generated in a water treatment plant: Preliminary assessment of toxicity in corn plants

Abstract

Sludge is the main waste generated in the water treatment plants (WTP), is from the water potabilization process, has a high concentration of solids and chemical elements such as aluminum and iron. For this reason, it cannot be discarded in water sources, requiring environmentally safe alternatives for proper disposal. The objective of this research was to evaluate the toxicity of the sludge generated in WTP associated with sugarcane bagasse and vinasse in the germination and initial growth of Zea mays L. The composting of the sludge was carried out for 60 days, with a mixture of bagasse and vinasse inoculated with Pleurotus sajor-caju. The compost was incorporated in the soil at doses of 0; 1; 10 and 100 compost/soil (g kg^-1). Ten seeds of Z. mays hybrid 2B433Hx from Dow Agrosciences were sown. After seven days, thinning was carried out, leaving five seedlings in each pot. The experimental design used was completely randomized with four replications. After 21 days of cultivation, the following were evaluated: percentage of emergency; emergency speed index; length and dry mass of roots and shoots. The dose of 100 g kg^-1 promoted reductions in the length of the aerial part and symptoms of nutritional deficiency caused by excess aluminum, iron and sodium in the sludge. For safe use, we recommend the dose of 10 g kg^-1 of the ETA sludge compound.