Avaliação da toxicidade de efluente de aterro sanitário utilizando semente de alface Lactuca sativa

Abstract

Given the concern about the negative impacts that landfill percolades can cause on the environment, the objective of this work was to evaluate the effluent toxicity of a landfill at several stages of treatment using lactuca sativa as bioindicators tests were performed, using petri dishes coated with qualitative filter paper, adding 20 seeds in each plate, each plate being humidified with 0.3 mL of diluted sample (100%, 50%, 25%, 12.5%, 6.25% and 3.125%). After seven days in germination greenhouse, the seeds germinated were counted and the lengths of the roots were verified. With the effluent of the maturation pond, tests were performed in a coagulation/flocculation laboratory using three types of coagulants, aluminum polychloride (PAC), Tanfloc SG and Moringa + KCl, at dosages of 1250 mg L-1, 1000 mg L-1 and 5000 mg L-1 respectively. Toxicity tests showed different effects on seedling germination and growth for the different treatment ponds, i.e., the higher the dilution of the sample, the higher the seedling growth. Coagulation/flocculation was efficient in reducing toxicity due to lactuca sativa presenting high germination rates and root growth at a concentration of 100% (treated gross effluent). It was found that lettuce seed is a great bioindicator, showing that even using the pond system, the effluent is still toxic, requiring coagulation/flocculation treatment.