Management challenges for a more decentralized treatment and reuse of domestic wastewater in metropolitan areas

Abstract

In a case study located in suburban sectors of the metropolitan area of the Lerma Valley (Valle de Lerma), in the province of Salta (Argentina), 24 informal decentralized wastewater treatment systems (DWWTS) were evaluated. The analyzed systems had three general configurations: A, septic tank; B, septic tank combined with upflow anaerobic sludge blanket (UASB) reactor; C, septic tank combined with UASB and a final filtration step. Statistically significant differences (p < 0.05) were observed in effluent quality, measured as total coliforms, thermotolerant coliforms, and chemical oxygen demand (COD). Treatment A was the most inefficient, and was statistically different from B and C; there were no significant differences between the latter two. Thermotolerant coliform concentrations were high in all analyzed systems and did not comply with local discharge standards in soakaway pits or in the ground. The lack of a final disinfection step in these systems is thus a weakness that needs to be addressed. The formal inclusion of DWWTS in urban planning could reduce overall investment costs, as long as the best technologies are selected for each case. Incorporation of DWWTS in formal urban planning requires an open debate in which the social perspectives of all relevant users need to be considered.

Key criteria for considering decentralization in municipal wastewater management

“…In the implementation of decentralized treatment systems in developing countries, it is necessary to align land use plans with water resource planning, taking into account the land uses, economic activities, spatial distribution, and geographical features of the cities to determine the level of centralization and evaluate the reuse potential in each sector. However, this implies reforms at the administrative and legal levels to promote decentralization as a solution not only for deficiencies in basic sanitation coverage but also as an alternative for economic return or added value through a resource-based sanitation approach ( Capodaglio, 2017 ; Hama et al., 2019 ; Iribarnegaray et al., 2018 ; Leigh and Lee, 2019 ; Xu et al., 2019 ).…”

Feasibility Evaluation of Wastewater Treatment Plant System: A Case Study of Domestic Wastewater System in Sleman Regency, Yogyakarta, Indonesia

“…Structure and pattern of urban green space has a significant role for the landscape ecology, especially in a compact city with a limited space (Liang et al, 2017). Iribarnegaray et al (2018) revealed that inclusion of DWWTS (Decentralized Wastewater Treatment Systems) in urban planning could reduce overall investment costs and the correct use of DWWTS could also allow a more secure scenario for effluent reuse. Cost effective innovative technology such as DMR (Domestic Multi-Recycler) is needed to restore poor water pollution that poses serious health threat to people in developing countries and to improve the soundness of water and wastewater recycling system (Uzuh et al, 2019).…”

The Future of Water: A Collection of Essays on “Disruptive” Technologies that may Transform the Water Sector in the Next 10 Years

“…They can lead to high nutrient loadings to groundwater, unless the density is rather low. Nitrogen control for septic systems has also been explored and several solutions have been identified, but have met with a variety of reliability challenges in real world applications (Oakley et al, 2010) (Iribarnegaray, Rodriguez-Alvarez, Moraña, Tejerina, & Seghezzo, 2018). Newer decentralized systems consider constructed wetlands (Machado, Beretta, Fragoso, & Duarte, 2017) as well as membrane bioreactors and miniaturized versions of centralized wastewater systems.…”