Avaliação do uso do permanganato de potássio em substituição ao cloro na pré-oxidação de água com cor moderada

Abstract

Chlorine is widely used in ETAs due to its high disinfectant and oxidizing power, low cost and easy handling and operation. Chlorine pre-oxidation of waters containing organic material of natural origin (MON) results in the formation of by-products that are harmful to human health, including trihalomethanes, which can cause diseases in humans, including cancer. Due to the potential of chlorine by-product generation, several alternative agents are being tested and used in ETAs. This work aims to evaluate the use of potassium permanganate as an alternative to chlorine in the pre-oxidation of water from a spring with moderate color as a strategy to reduce the formation of disinfection by-products (SPDs). For this, jar tests were performed (without pre-oxidation, with pre-oxidation using chlorine, with pre-oxidation using potassium permanganate), simulating the treatment configuration of the Jiqui WTP: direct in-line descending filtration. In the trials without pre-oxidation, PAC 12% proved effective, especially at a dose of 20 mg/L. For the trials with pre-oxidation associated with PAC 12%, chlorine (dose of 3 mg/L) reduced the true color and ABS-254 without affecting turbidity, while potassium permanganate (dose of 1 mg/L) reduced the true color and ABS-254 in filtered water, but resulted in increased turbidity. The tests were performed only in the dry season, it is recommended that the use of potassium permanganate as a pre-oxidant be performed also in the rainy season.