Desenvolvimento, aplicação e avaliação de sistema de indicadores de desempenho de estações de tratamento de água

Abstract

The overall objective of this research was to develop, implement and evaluate a system of performance indicators (PI) for water treatment plants (WTP) under the perspective of a regulatory agency. The methodology used consisted of four main steps: (i) survey of PI systems, (ii) selection of elements of PI system, (iii) application of the system developed and (iv) evaluation the proposed system. The survey covered ten major national and international organizations related to research, management and/or regulation, resulting in 423 PI. There was a small proportion of ID specific for WTP (9 %). In water supply systems, the evaluation themes which have most importance were infrastructure (36% of ID) and economy (25%), while for WTP was the theme public health (57%). At first it was proposed a PI system starting from themes, criteria and indicators which selection was based on recommendations presented in literature. The set was discussed with the regulatory agency and the service provider, resulting in a system with three subjects, four criteria and 19 PI, followed by the respective reference values and performance targets. For application of the developed system, monitored water quality data (daily averages) was used, average monthly flows and personnel, chemicals and electric costs of six WTP, with project flow rates between 36 L s-1 and 5.500 L s-1 during the period from 2002 to 2011. By dynamic analysis, it was found that the PI of economy and infrastructure themes showed no significant seasonal variation (Kruskal-Wallis test). On the other hand the PI theme linked to public health proved to be the most impacted by the seasonal variation. Significant trends were observed in 29 of 100 cases analyzed (Mann-Kendall test). The comparative analysis between WTP was performed by cluster analysis the Kruskal-Wallis test followed by multiple comparisons tests. By the end, it was conducted a factor analysis/principal components in order to identify inter-related groups of PI, point out the main PI in each evaluation criterion and investigate the possibility to reduce the number of PI. It is believed that methods employed for selection of system elements, data processing and interpretation of results, as well as discussions about the limits and profile acting, aspects of water treatment and methods of performance measurement, may contribute to the development and improvement of indirect supervision and regulation.