Contabilidade ambiental e econômica da redução no consumo de água potável e do uso de água de chuva na Subprefeitura Capela do Socorro – São Paulo

Resumo (EN)

The availability of drinking water in large metropolitan areas is a critical problem, whose main causes are: increased population density, deforestation and its not rational use due to lack of environmental education. It is within this context that falls the concern with an appropriate use of water in their different quality levels and the attainment of a better efficiency in its treatment and use. The State of São Paulo State as well as the Municipality of São Paulo has passed laws involving rational use of water, whose goal is the 20% reduction in potable water consumption. The Municipality under contract with the Basic Sanitation Sanitation Company of the State of São Paulo (SABESP), is implementing the Program for the Rational Use of Water (PURA). The aim of this work is to evaluate economically and environmentally, through the emergy accounting theory developed by H.T. Odum, 1996, the rationalization of water use in two scenarios at the Capela do Socorro Municipal building. The first scenario comprises the PURA program implementation. The second scenario involves rainwater use. While the emergetic environmental accounting considers also the natural services needed to produce a good, the economical point of view only considers the market value. Emergy accounting, by using a common metric, quantifies in “sej” - solar energy joule, the renewable, non renewable and purchased resources ( corresponding to nature work, labour and money involved in goods and services) that enter the system. Each input is multiplied by the emergy/unit value, considered as a transformation factor, and calculated according to Odum theory. The time frame considered is one year. The first scenario shows a decrease of 31.8 % in potable water consumption, and the second one a reduction of 21.2%, when compared to values of 2012, before interventions. The annual net environmental benefit in the first scenario is 1.37E+16 sej and the economical benefit is R$10,984.00, with an environmental payback of 9 months and an economical of 66 months. The cost/benefit ratio shows that there is a return of 40 sej for each sej invested, and a return of R$5.40 for each R$. The scenario of water rain use shows an annual net environmental and economical benefit of 7.06E+15 sej and de R$ 7,258.00, respectively. The environmental payback is 125 months while de economic one is 94 months. Cost/benefit ratios shows that for each invested sej there is a return of 6.8 sej and for each R$ a return of R$5.00.