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A multi-criteria analysis of building level graywater reuse for personal hygiene – new article co-authored by Timos Karpouzoglou

Timos Karpouzoglou has been with the Division since 2018, and is working closely with the KTH WaterCentre, where he previously was a research coordinator. His current research is focused on urban water infrastructure and is informed by social sciences and the humanities. In a new article, together with Jörgen Wallin (KTH) and Jesper Knutsson (Chalmers), Timos investigates how water demand globally exceeds over available water supply, and takes a closer look at the reuse of bathroom graywater for shower and bathroom sink hot water. The investigation focuses on water and energy savings, water treatment, economic benefit and investigates the main actors and institutions that are involved. “A multi-criteria analysis of building level graywater reuse for personal hygiene” was published in the 2021 December issue of Resources, Conservation & Recycling Advances.
Water Infrastructure. Photo: iStock

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.

Keywords

Graywater recovery, Graywater reuse, Heat recovery in graywater, Energy conservation, Water saving, Water reuse, Recycled water

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