Diante das frequentes crises hídricas registradas no Brasil, o reuso industrial de água e de efluente tratado é um importante instrumento na gestão dos recursos hídricos, sobretudo nas grandes cidades. O objetivo do trabalho foi analisar a oportunidade de redução do consumo de água potável em indústria de fabricação de estruturas em concreto, considerando requisitos quantitativos, qualitativos e econômico-financeiros. A metodologia utilizada baseou-se em: coletas de campo para determinar a oferta e a demanda de água de reuso no empreendimento estudado; levantamento da qualidade da água de reuso requerida; proposta de tratamento e avaliação do investimento necessário. Os resultados mostraram um potencial de redução de 61% da demanda mensal de água potável do empreendimento analisado, com um baixo investimento (cerca de R$ 3.000,00). Concluiu-se que o reuso de água pode ser considerado uma alternativa estratégica para a empresa, sobretudo em um cenário de cobrança pelo uso da água e de restrição em caso de escassez.

This paper analyzes the impact of methane emissions taxation on the recovery of the investments required for implementing technologies that use biogas energy in small wastewater treatment plants (WWTPs) in Brazil. It is based on the hypothesis that the adoption of a national methane emission tax policy would encourage small WWTPs to become sustainable power plants. The procedure involved 173 anaerobic plants to analyze: (a) methane production; (b) available useful energy; (c) investments and avoided costs for implementing STHIL system (thermal drying sludge) and motor generator (electricity generation); (d) financial impact for two scenarios (C1: no emissions tax; C2: with tax). Positive environmental and financial results were observed for WWTPs, varying according to the period of time analyzed for both technologies. Investments must be made in cogeneration in anaerobic WWTPs for achieving satisfactory results. Taxation must not be viewed simply as a punitive instrument; on the contrary, it should be seen as a tool to encourage continuous process improvement. The circular economy may support the enlargement of the wastewater collection and treatment system, guaranteeing widespread sanitation conditions in urban areas. However, the actual implementation of a methane emission tax in Brazil still requires many rounds of discussion among sanitation companies, government, and civil society, to establish emission limits, and unit taxes, as well as to consolidate a carbon trade to follow through with this decision in the sanitation sector.