A multi-criteria analysis of building level graywater reuse for personal hygiene

Jörgen Wallin,Jesper Knutsson,Timos Karpouzoglou

doi:10.1016/j.rcradv.2021.200054

Abstract

Globally an increasing number of people are facing water scarcity. To address the challenge, measures to reduce water demand are investigated in the world. In the present paper, a novel approach to reuse bathroom graywater for shower and bathroom sink hot water is investigated. The investigation focuses on water and energy savings, water treatment, economic benefit and investigates the main actors and institutions that are involved.The main results are that there is significant potential for water and energy savings with a positive economic benefit. Water savings of domestic hot water up to 91 % and energy savings up to 55 % were observed. The investigated treatment plant produces recycled graywater with a quality close to drinking water standards.The investigation also presents that the reason for the positive economic benefit will depend on the utility tariffs. Therefore, two locations with different utility rate structures were investigated, Gothenburg, Sweden and Settle, USA. In Gothenburg, the utility cost for energy was the driver of economic benefit and in Seattle it was the water and wastewater cost that was the driver. The return of investment for the system and installation was shown to be 3.7 years in Gothenburg and 2.4 years in Seattle.

Highlights

An increasing number of people are living under conditions of water scarcity
The aim of this paper is to provide a multi-criteria analysis with a holistic view on the potential, challenges, and possibilities for onsite graywater reuse systems for personal hygiene purposes
The fact that average total organic carbon (TOC) values for the EDI reject was 9.73 mg/l while chemical oxygen de mand (COD) was 0 mg/l is attributed to residual citric acid in the effluent, which is detected by the TOC analysis but not with the COD analysis

Summary

Introduction

An increasing number of people are living under conditions of water scarcity. Due to increasing demand and anticipated climate changes, 4.8–5.7 billion people could be living in areas with potential water scarcity at least one month per year by 2050 A (Burek et al, 2016). Water reuse schemes have been gaining increased attention as an alternative approach to provide water to support human activities (Oteng-Peprah et al, 2018). Graywater reuse for various applications have been previously demonstrated and there is a significant number of papers describing graywater reuse for non-contact purposes. There is a lack of both regulatory and public support for potable reuse of recycled gray water which is a significant obstacle to novel in-building reuse appli cations (Oteng-Peprah et al, 2018; Vuppaladadiyam et al, 2019)

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Conclusion