Diretrizes para plano de segurança da água para soluções alternativas de abastecimento em comunidades rurais dispersas.

Abstract

The use of alternative water supply solutions for human consumption is an option to try to mitigate the problem of access to water in rural areas for dispersed populations. The great challenge for managers of these solutions is maintaining water safety, since they are multi-entry systems, which are difficult to predict hazards. The management model recommended for supply systems, collective alternative water supply solutions for human consumption (SAC) and individual alternative water supply solutions for human consumption (SAI), by the World Health Organization (WHO) and subsequently by Ordinance GM/MS No. 888 of 2021, is the Water Security Plan (PSA), a robust and reliable tool, which is therefore difficult to implement by these solutions. Previous studies have found the need to simplify the PSA, while maintaining the benefits for the population with its implementation of this instrument, which is based on the principle of multiple barriers, which can be seen as a series of good practices to ensure the safety of the quality of water available for human consumption. One of the tools used by the PSA is risk analysis. This tool is essential for identifying hazards in water supply. It allows us to recognize the main risks and, based on this information, develop control measures to mitigate the problems identified. Thus, the study aimed to propose guidelines for a water safety plan for alternative supply solutions in rural communities, in a simplified way, enabling its application in dispersed locations. The study evaluated five alternative supply solutions, namely: rainwater harvesting, shallow or tubular wells, supply with conventional network, direct collection from surface sources (rivers, springs and reservoirs) and supply by transport vehicle (regulated or autonomous tanker trucks). To this end, process risk analysis was used with the Hazard and Operability Study (HAZOP) methodology to identify the main deviations, their consequences and the necessary measures for each supply source and Failure Mode and Effect Analysis (FMEA) of product to prioritize the hazards in the water supply. The HAZOP identified sediment accumulation, maintenance failures and interruptions in water supply as the main operational deviations, which compromise the sanitary safety of the water. The FMEA identified the presence of Escherichia coli and total coliforms as the main risks to the product, followed by indicators of low free residual chlorine (FRC) concentration and high turbidity. Based on these analyses, action protocols and practical recommendations for alternative solutions were developed, as well as a checklist of sanitary safety procedures for alternative supply solutions and the actions of the PSA audit process. At the same time, a compact and easy-to-operate ozonation disinfection system was developed, aiming to be an alternative as a measure for adequacy and control of the PSA, helping to maintain the microbial quality of the water. The system obtained good results in the inactivation of total coliforms and Escherichia coli in 100% of the analyses of water from cisterns and wells in the sample universe of n = 30. However, it had a lower efficiency in water coming from direct capture of reservoirs, obtaining an efficiency of 86.66% in the removal of total coliforms and 90% of Escherichia coli.