Light or Dark Greywater for Water Reuse? Economic Assessment of On-Site Greywater Treatment Systems in Rural Areas

Abstract

Water scarcity is causing a great impact on the population. Rural areas are most affected by often lacking a stable water supply, being more susceptible to the impact of drought events, and with greater risk of contamination due to the lack of appropriate water treatment systems. Decentralized greywater treatment systems for water reuse in rural areas can be a powerful alternative to alleviate these impacts. However, the economic feasibility of these systems must be thoroughly evaluated. This study reports an economic analysis carried out on the viability of greywater reuse considering scenarios with light greywater or dark greywater to be treated. For this, data obtained from the assembly and monitoring of greywater treatment systems located in the north-central zone of Chile, supplemented with data obtained from the literature were used. The results showed that both scenarios are not economically viable, since the investment and operating costs are not amortized by the savings in water. In both evaluated cases (public schools), the economic indicators were less negative when treating light greywater compared with the sum of light greywater and dark greywater as the inlet water to be treated. The investment and operating costs restrict the implementation of these water reuse systems, since in the evaluation period (20 years) a return on the initial investment is not achieved. Even so, our results suggest that the best alternative to reuse greywater in small-scale decentralized systems is to treat light greywater, but it is necessary to consider a state subsidy that not only supports capital costs but also reduces operating and maintenance costs. These findings support the idea that the type of water to be treated is a factor to consider in the implementation of decentralized greywater treatment systems for the reuse of water in rural areas and can help decision-making on the design and configuration of these systems.

Water Context in Latin America and the Caribbean: Distribution, Regulations and Prospects for Water Reuse and Reclamation

“…In addition, the lack of legislation or regulatory framework can contribute to the bad practice of greywater reuse, which could have bad effects on health. In addition, some studies show the need for incentives or government subsidies for the implementation of treatment systems [124,135].…”

Economic Incentives in Stormwater Management: A Study of Practice Gaps in Poland

“…According to the ratio calculated in this way, the investment is financially profitable for the investor if the B/C is higher than zero. The B/C ratio is expressed by the formula [72,73]:…”

Assessment of Greywater Reuse in a University Building in a Hyper-Arid Region: Quantity, Quality, and Social Acceptance

“…Greywater is one of those alternatives, especially for reuse in activities that do not require high-quality water, such as toilet flushing, construction, car washing, garden watering, and others [1,13,14]. It is abundant and sustainable because its availability does not rely on precipitation, and its treatment requires less energy than mixed wastewater [2,15,16]. Regarding households, light greywater is the wastewater produced by bathing, handwashing, and showers, whereas dark greywater includes kitchen basins and laundry [15,17].…”

“…It is abundant and sustainable because its availability does not rely on precipitation, and its treatment requires less energy than mixed wastewater [2,15,16]. Regarding households, light greywater is the wastewater produced by bathing, handwashing, and showers, whereas dark greywater includes kitchen basins and laundry [15,17]. In general, greywater is wastewater that does not consider any blackwater discharge, such as toilet effluents [1].…”