Avaliação da eficiência do clorador por difusão na desinfecção de águas sintéticas de cor e turbidez moderadas

Abstract

ABSTRACT The precariousness of sanitation in Brazil, as confirmed by the latest research carried out, mainly by the IBGE, indicates that a significant portion of the population lacks a supply of drinking water and some type of domestic sewage treatment system, and this is particularly true for the population living in small or rural communities. In view of this problem, this study, carried out on a pilot scale in a laboratory, evaluated the performance of the diffusion chlorinator, which is a low-cost disinfection device, especially designed for groundwater, applicable to the conditions of numerous small Brazilian communities. The work was carried out in the Practical Classes Laboratory of the Department of Sanitary and Environmental Engineering, of the School of Engineering of the Federal University of Minas Gerais, where the functioning of three simulated shallow wells was evaluated, into which bacteriological contamination with different microorganisms was introduced. Disinfection results were obtained after the introduction of the diffusion chlorinator, with the variation of three study parameters: the active chlorine content (calcium hypochlorite and chlorinated lime), the sand/disinfectant ratio and the flow rate variation, applied to synthetic waters with true color and turbidity levels above those recommended by Ordinance 36/90. The experimental apparatus, consisting of two 500-liter reservoirs for the study waters, a 50-liter distribution box and three 100-liter drums, with different daily flow rates circulating in each of them, simulated the operation of shallow wells subject to these conditions. The chlorinators were installed in the simulated wells and the disinfection efficiency was evaluated over a period of 7 to 26 days. During the runs carried out with calcium hypochlorite, the performance of the device, with respect to the disinfectant effect, was considered good; Due to the chlorine residual peaks, it has a wide range of uses at flow rates above 2.000 l/d. The runs carried out with chlorinated lime showed irregular performance from the disinfection point of view. It is worth mentioning that, for both disinfectants, complete inactivation of E. coli was observed whenever the residual chlorine was above 0,10 mg/l Cl2. Regarding the variation in the proposed sand/disinfectant ratio, no significant difference was recorded in the conditions applied in the experiment.