VARIAÇÃO DA CONCENTRAÇÃO DE BACTÉRIAS INDICADORAS DE CONTAMINAÇÃO FECAL NAS DIVERSAS FASES DO PROCESSO DE TRATAMENTO DE ÁGUA DE ABASTECIMENTO PÚBLICO DA CIDADE DE ARARAQUARA - SÃO PAULO

Abstract

The quantity and quality of the water supply has an fundamental importance for health of the population. In order to guarantee the water quality is necessary to control the whole treatment process. The bacteriological potability is determined through verification of the presence of coliform group bacteria (total and fecal), indicative of fecal pollution, the main responsible for the transmission of infectious diseases to the population. The objective of this research was to verify the effectiveness of the treatment processes performed at the Water Treatment Stations in Arararaquara and to determine the concentrations of total and fecal coliform bacteria in each stage of the treatment process - raw water, after floculation/decantation, filtration and chlorination - related with the turbidity and, at last, evaluate whether the water is in accordance with the Ministry of Health and State of São Paulo patterns. The most probable number (MPN/100mL) of total coliform bacteria and fecal coliforms was determined by the fermentation in multiple tubes technique, presuntive and confirmative tests. The analyses were performed monthly during a period of twelve months. In all the collections, it was verified that the rude water had a great amount of coliforme ( MPN/100mL), hence the desinfection phase that has a fundamental importance for the water that serves the population and the quality patterns. The conclusion is that a MPN/100mL reduction of total and fecal coliform bacteria occurred together with the water turbidity in the different stages of the treatment process and that the water produced by ETAs is in accordance with the determined patterns for the studied variables.