Instrumentação óptica aplicada à análise de qualidade e tratamento de água e esgoto: soluções de baixo custo para estações de pequeno porte

Abstract

In this work, the use of image processing techniques for monitoring important attributes in drinking water and wastewater treatment processes is proposed, so that the glimpsed measuring instruments can provide information for automatic dosing systems of chemical products without overpricing them. The purpose is to stimulate the use of automation systems in treatment plants, especially in compact ones, for which the reduction of costs with these systems and with the operational workforce is more impacting and, in some cases, can be a decisive factor for deployments in isolated communities, farms, small industries, universities and other localities. At first, an automatic dosing system for coagulant product was developed in three steps: in the first one, a technique to measure water turbidity from images captured by a common webcam was proposed, and reliable results were obtained. In the second step, a new algorithm for the implementation of fuzzy systems in compact digital controllers was proposed, contributing for the use of this kind of hardware in the desired automation systems. Integrating the previous steps, a prototype of the image processing based turbidity meter and a pilot plant were builded, demonstrating the coherence of the implemented dosing system and its suitability to be installed on a real drinking water treatment plant. In another effort, a work sequence similar to the previous one was initiated with the development of a method to monitor the disinfection of wastewaters subjected to chlorination processes. Based on evaluations of the biological activity detected in samples collected at a wastewater treatment plant, the proposed technique was able to establish if the disinfections were accomplished or not, allowing the creation of a low cost instrument to feedback automatic chlorine dosing systems.