Optimal Implementation of Wastewater Reuse in Existing Sewerage Systems to Improve Resilience and Sustainability in Water Supply Systems

A transition from conventional centralized to hybrid decentralized systems has been increasingly advised recently due to their capability to enhance the resilience and sustainability of urban water supply systems. Reusing treated wastewater for non-potable purposes is a promising opportunity toward the aforementioned resolutions. In this study, we present two optimization models for integrating reusing systems into existing sewerage systems to bridge the supply–demand gap in an existing water supply system. In Model-1, the supply–demand gap is bridged by introducing on-site graywater treatment and reuse, and in Model-2, the gap is bridged by decentralized wastewater treatment and reuse. The applicability of the proposed models is evaluated using two test cases: one a proof-of-concept hypothetical network and the other a near realistic network based on the sewerage network in Chennai, India. The results show that the proposed models outperform the existing approaches by achieving more than a 20% reduction in the cost of procuring water and more than a 36% reduction in the demand for freshwater through the implementation of local on-site graywater reuse for both test cases. These numbers are about 12% and 34% respectively for the implementation of decentralized wastewater treatment and reuse.

Graywater Reuse: The Effects on Income and Agricultural Production Sustainability of Family Farming Systems in the Semiarid Region of Ceará, Brazil

The semi-arid region of Ceará is a Brazilian area that is exposed to long and frequent periods of drought. Water scarcity is a threat to the population’s well-being and agricultural activities. We evaluated the effects of graywater reuse for agriculture on income and sustainability of agricultural production in the municipality of Iguatu, located in the semiarid region of the state of Ceará. It is an important research because it deals with a strategy that aims to reduce farmers’ vulnerability to the lack of water. There are no studies that assess the impacts of water reuse in the region. The propensity score matching technique was applied, and primary data were obtained by interviewing beneficiaries (treated group) and non-beneficiaries (control group). The results showed that the program has effects on sustainable agricultural production of small farmers because of the use of non-aggressive agricultural practices. In the group of beneficiaries, the income is 21.9% higher than of that in the group of non-beneficiaries. In addition, families that adopt water reuse have 26.8% higher levels of sustainability than those that do not adopt this strategy of living with drought.

Comparative study on decentralized treatment technologies for sewage and graywater reuse – a review

Currently, reservoirs, lakes, rivers etc. are being overloaded by the demand for fresh water, due to rapid industrialization and population explosion, and also the effluents from industries and domestic wastewater are continuously polluting these resources. To address this issue, several decentralized wastewater treatment system (DWTS) have been installed all over the globe to reuse and recycle wastewater/graywater for non-potable uses such as fire protection, toilet-flushing, and landscape irrigation. In this review, a comparison between different DWTS was carried out to evaluate their performance, merits and limitations. Hybrid technologies like the electrically enhanced biomass concentrator reactor and integration of physical/ biological methods with bio-electrochemical systems such as microbial fuel cells were found to be the most promising methods for near complete removal of pollutants from wastewater and also the issue of membrane fouling was reduced to a good extent.

Are Green Infrastructure Strategies Suitable in Arid Climates? A Design Feasibility Study from Jeddah City, Saudi Arabia

This paper describes the feasibility and probable benefits associated with greening the Tahliah Channel, a concrete drainage channel that was originally built to relieve urban flooding in Jeddah City, Saudi Arabia. It includes an estimation of irrigation needs for channel greening based on a standardized planting specification. The study also demonstrates alternative strategies for meeting the required irrigation demand, including water harvesting and graywater reuse on a residential scale. The study shows that greening Tahliah Channel is possible relying mainly on graywater reuse from the surrounding buildings. Also, the study shows that rainwater harvesting is not a reliable source for irrigation. Rather, it can cover only part of the irrigation needs (6%) and so can be used as a secondary supporting source. The positive results of this case study will be of interest to those in arid countries who are looking to upgrade and replace traditional, single function drainage infrastructure with more sustainable, green infrastructure systems. More specifically, the objectives of the study are consistent with the goals of the Saudi government’s ongoing initiative that advocates for more resilient and sustainable cities. (Vision 2030 year).