Alternative mechanisms of charging for use of water resources in wastewater assimilation

Abstract

Nowadays in most hydrological basins in Brazil, the charging mechanism of water use for effluents assimilation in inland surface water bodies is based on the emitted organic load parameter quantified in terms of Biochemical Oxygen Demand (BOD). This method is insufficient given the broad variety and compositions of discharges. Therefore, the objectives of the study are to propose alternative charging mechanisms for the qualitative use of water resources, aiming to insert, beside BOD, other parameters as calculation criteria; and to evaluate the charging potential for the Doce River hydrological basin. Two methods were proposed: the Limiting Population Equivalent (LPE) and the Compromised/Committed Volume (CV). Five water quality parameters were established: Biochemical Oxygen Demand, Chemical Oxygen Demand, Total Suspended Solids, Ammonia Nitrogen, and Phosphorus. The proposed mechanisms contemplated, from a broader perspective, the real problem concerning water quality in the Doce River basin. Simulations showed that phosphorus was a problem of concern for managing water resources in the specific basin. The method of Limiting Population Equivalent was considered of easiest application and understanding by its users.Keywords: Charging mechanism; Compromised/Committed volume; Population equivalent. RESUMOAtualmente, a cobrança pelo uso da água para fins de assimilação de efluentes é, na maioria das bacias hidrográficas brasileiras, baseada no cálculo da carga orgânica emitida, quantificada em termos da Demanda Bioquímica de Oxigênio (DBO). Trata-se de um método pouco abrangente considerando-se a variedade e composição dos efluentes comumente lançados. Assim, objetivou-se propor mecanismos alternativos de cobrança pelo uso qualitativo dos recursos hídricos, procurando-se a inserção de novos parâmetros, além da DBO, como critério de cálculo; e avaliar o potencial de arrecadação tomando-se como estudo de caso a bacia hidrográfica do rio Doce. Foram duas as propostas apresentadas: a do Equivalente Populacional Limitante (EPL) e a do Volume Comprometido (VC); estabelecendo-se a aplicação de 5 parâmetros de qualidade de água: Demanda Bioquímica de Oxigênio, Demanda Química de Oxigênio, Sólidos Suspensos Totais, Nitrogênio Amoniacal e Fósforo. Os mecanismos propostos contemplaram, de forma mais ampla, o real problema da qualidade das águas na bacia do Doce; e as simulações evidenciaram o fósforo como um problema preocupante para a gestão dos recursos hídricos na referida bacia. A proposta do Equivalente Populacional Limitante foi considerada a de mais fácil aplicação e entendimento pelos usuários.

Concentration of water use permit and volume-based fees in Ceará, Brazil

“…Adding or changing of components in existing or proposed charging models can certainly increase the amount to be charged to use sectors. Oliveira et al (2017) simulated an impact of 64% to almost 500% on the sanitation sector in the Rio Doce Basin (Minas Gerais and Espírito Santo), by increasing the charging model in force with effluent release parameters. Aquino et al (2013) simulated the application of fees for investment recovering in water infrastructure in water charge in Ceará, with impacts varying from 6% to 17% (industry), from 86% to 226% (supply), and from 770% to 2,465% (irrigation).…”

“…First, that different use sectors must have different levels of concentration of access (permitting) to water (Cullis & van Koppen, 2007;Liu et al, 2019). Second, that increases in charging due to the incorporation of a new fee (in the case of this research, the permit fee) have different economic impacts to users (Aquino et al, 2013;Oliveira et al, 2017). Third, that more vulnerable sectors, such as irrigation, are more sensitive to increases in the cost of water (Frija et al, 2011).…”