USE OF COAGULANT FROM PLANT ORIGIN AS AN ALTERNATIVE IN THE TREATMENT OF EFFLUENTS FROM SANITATION INDUSTRY

Resumo

The use of aluminum sulphate-based coagulants, associated with flocculants, is frequent in the treatment of effluents. However, as a by-product, chemical sludge is produced, containing aluminum salts, which pollute the environment. The present work aimed to evaluate the performance of a vegetable coagulant based on tannin in the treatment of effluent from a sanitizing industry. Three experiments were carried out, using 1.0 % w/v of aluminum sulfate and vegetable coagulant, and using 0.25 % w/v of the vegetable coagulant. According to the tests, the vegetable coagulant at 0.25 % m/v reduced 60.4 % of turbidity, 71.0 % of total phosphorus, 98.0 % of anionic surfactants and completely removed animal and vegetable oils and greases and total suspended solids, generating an aluminum-free sludge. The vegetable coagulant acted simultaneously as a coagulant and flocculant and did not require adjustment of effluent pH, not requiring the use of flocculants and alkaline agents, in addition to being effective at lower dosages in relation to the coagulant based on aluminum sulfate. Therefore, the use of vegetable coagulant is technically feasible due to its biodegradability, sludge application potential, and because it does not require special investments or major changes to the existing effluent treatment infrastructure.