Aplicação de técnicas alternativas no tratamento de água subterrânea para comunidades rurais

Abstract

In Brazil, although thousands of people still do not have access to a quality water supply, they resort to individual solutions, such as the use of underground water, which is sometimes of lower quality than recommended by legislation. There are several alternatives that can mitigate the situation, such as the use of slow filters with casual and non-occasional filtering media or the use of natural coagulants/flocculants, making it possible to reduce social problems adverse to water supply, especially for the rural population, which they live in more isolated places without a quality water supply. Therefore, this study's main objective was to verify the efficiency of water filter treatments using conventional and non-conventional slow, and using natural coagulant/flocculant from cactus, in the treatment of groundwater. Thereby, in slow filtration, three downward flow filters were used, these being a filter with sand (FA), a filter with sand and activated carbon (FACA) and a filter with sand and biochar from cactus (FABC). For the treatment of water with coagulation/flocculation, the best result was evaluated with the use of coagulant/flocculant from cactus in the treatment of groundwater, for subsequent analysis of the efficiency of the aforementioned treatment in comparison with FABC. Thus, according to statistical tests, the results indicated similar performance between conventional and non-conventional filters for the parameters apparent color, turbidity, electrical conductivity and total iron, with significant differences between raw and filtered water. Besides, the hardness and electrical conductivity parameters had similar behavior with the use of filters, having moderately higher values with FABC only until the end of the first filtration career. In coagulation/flocculation, 100% of the true color, turbidity and chemical oxygen demand were removed, in addition to 97% of the total iron. Furthermore, both treatments did not show significant changes in relation to temperature and pH. When comparing the treatments (coagulation/flocculation and slow filtration), they showed statistically significant differences (except for the total iron parameter), demonstrating that, although both methodologies present significant removals in the evaluated water quality parameters, they have behavior of different treatments. Therefore, the results indicated that both alternative solutions significantly improved water quality, making them viable for reducing inequalities regarding the availability of quality water between rural and urban areas.