Wastewater treatment systems selection inside watersheds by using multiobjective analysis

Abstract

In order to determine required wastewater treatment plants (WWTP's) efficiencies, several methodologies have been proposed to assist the sewage treatment systems process selection, usually aiming to achieve economic objectives. However, in water resources problems solving, search involves multiple and conflicting objectives. This work used, for Pardo's river basin (Espírito Santo State, Brazil), water quality simulation model, optimization technique and multiobjective analysis for selecting sewage treatment systems, taking into account Brazilian environmental effluents Biochemical Oxygen Demand standards, imposed by CONAMA Resolution 430/2011. After proposing an optimization model that allowed the estimation of minimum organic matter removal efficiencies, a multiobjective analysis was applied by using the ELECTRE III method, which selected sewage treatment systems for localities responsible for domestic wastewater disposal in Pardo's river basin. The results indicated that keeping the effluents standards can produce treatment plants overestimation and inadequate allocated financial resources distribution for sewage treatment plants implementation. Treatment systems such as Submerged Aerated Biofilters (with Nitrification), Wetlands and Facultative Ponds were the most selected, considering different contexts appreciated in this work.

Prospects for reducing the contribution of organic load in a water basin with significant urban occupation

“…Organic loads and removal percentages per water quality simulation scenario of the Poti River -results associated with the use of Optimization Model 2.treatment efforts to remove organic loads were reduced. A similar behavior was observed byBringer, Reis and Mendonça (2018),Rocha et al (2021),Sá et al (2019) andValory, Reis and Mendonça (2016) when evaluating the final disposal of domestic effluents in the Pardo and Santa Maria da…”

“…Sewage treatment is generally the main way to control pollution and improve water quality in water bodies. In this scenario, cost is usually the most important factor in choosing treatment plants (ALMEIDA et al, 2022), and the water bodies' self-purification capacities help to reduce costs and implement pollution control measures since they complement the processes that occur in sewage treatment systems (BRINGER, REIS and MENDONÇA, 2018).…”

“…Examples of works that use the association between water quality modeling and optimization techniques are Aghasian et al (2019), Almeida et al (2022, Bringer, Reis and Mendonça (2018), Fantin, Reis and Mendonça (2017), Rocha et al (2021, Sá et al (2019) and Santoro, Reis and Mendonça (2016). The optimization models suggested by these authors were built through the combination of different objective functions and sets of constraints.…”