UT Professor’ research results published in Elsevier Journal of Cleaner Production

30 November 2022 | 11:06 Code : 31657 News

visits:125

Volume 382, 1 January 2023, 135299

Life cycle assessment of reverse osmosis for high-salinity seawater desalination process: Potable and industrial water production

Author links open overlay panel Samaneh Fayyaz^aeSiavash Khadem Masjedi^bAli Kazemi^cEshaghKhaki^dMazaher Moeinaddini^eStigIrving Olsen^b

https://doi.org/10.1016/j.jclepro.2022.135299 Get rights and content

Abstract

Seawater desalination is applied worldwide as a solution to water supply, especially for countries with limited water resources. The industry sector is the primary water user in varying qualities for different purposes. Desalination of seawater is increasingly implemented in the Persian Gulf region, but the environmental impacts have not been adequately assessed. This study assessed the life cycle environmental impacts of potable and industrial grade water with the most detailed inventory, including the impact of the brine rejected to the sea and solid wastes using SimaPro software. The 18 ReCiPe midpoint H impact categories, three endpoint damage categories, and the single score have also been specified. The seawater reverse osmosis powered by fossil fuels was studied to produce potable and industrial water. Electricity has the highest contribution to most of the studied impact categories. The sensitivity analysis showed that a 10% decrease in electricity consumption could reduce fossil resource scarcity and global warming by about 5% for potable and industrial water. The single total score for Sea water reverse osmosis (SWRO) potable and industrial water production are 98.83 and 168.54 mPt, respectively, mainly related to the human health damage category. The cumulative energy demand assessment showed that non-renewable biomass and renewable (wind, solar and geothermal) have the least energy intensity, respectively. To the best of our knowledge, the life cycle assessment of SWRO industrial water production has not been performed before. The current study would be a baseline for further comparisons. The potable water production results agree with the other studies despite having a much more detailed inventory.

Graphical abstract

Introduction

Because of economic growth, water consumption is increasing worldwide, specifically in developing countries, over the coming decades. Increasing water demand and decreasing water supply will intensify water stress in the future (Edwards et al., 2019). Seawater desalination, a non-conventional inexhaustible water supply, is a viable solution worldwide to the water scarcity problem. In Gulf Cooperation Council (GCC) countries with rare water supplies, desalination is the only possible source of water (Darwish and Mohtar, 2013). The most commonly used technology for desalination and the cheapest process is reverse osmosis (RO) due to higher energy efficiency than other technologies. It is estimated that brine production will increase from 40 km³ in 2012 to 240 km³ in 2050 (Gude and Fthenakis, 2020). In 2018, almost 20,000 desalination plants produced 97.4 million m³/d of water worldwide, and 59% of desalination capacity is used for seawater desalination (Gude and Fthenakis, 2020; IDA, 2019).

The Persian Gulf is a shallow sea connected to the Gulf of Oman with an average of 50 m in depth. The arid climate caused a high evaporation rate (about 1.84 m³/yr) compared to the freshwater supply of approximately 0.28 m³/yr. The high rate of evaporation in comparison to the freshwater recharge rate has made it hyper-salinated. The countries around the Persian Gulf share 50% of global seawater desalination (Jones et al., 2019; Lattemann and Höpner, 2008). Of the top 20 desalination plants in the world, 12 sites are situated around the Persian Gulf (Gleick, 2018). Approximately 5 km³ of fresh water is taken from (Gleick, 2018), and 12 km³ of brine is discharged into the Persian Gulf annually (Jones et al., 2019). The salt discharge volume is estimated at 2.75E+05 m³ per day. The overall salinity is not sensitive to the release, but the regional sensitivity is high in varying degrees and may lead to severe consequences for the biological environment. Dumping of brine impacts the marine ecosystem and dynamic and thermodynamic processes (Ahmed and Anwar, 2012; Gleick, 2018; Khan and Al-Ghouti, 2021; Panagopoulos and Haralambous, 2020); desalination has been implemented in the Middle East and North African countries (MENA) for years, but its environmental impact of it has not been adequately assessed (Mannan et al., 2019). In the SWRO process, elements such as chlorine, copper sulfate, sodium bisulfate, ferric chloride, sulfuric acid, etc., are added to the water and rejected to sea as brine (Ahmed and Anwar, 2012; Lattemann and Höpner, 2008b; Panagopoulos and Haralambous, 2020). The industry sector consumes about 62% of desalinated water, and the rest, 38%, is dedicated to domestic use (Gude, 2016).

In industries, water is used in various applications like cooling towers, boilers, production, firefighting, and drinking. Cooling towers and boilers consume the highest share. The previous studies primarily focus on drinking water quality desalination (Venzke et al., 2017). Tarpani et al. (2021) compared and evaluated life cycle assessment (LCA) of three alternative techniques for increasing potable water supply in cities in the Global South including; SWRO, an up-flow anaerobic sludge blanket reactor (UASB) followed by ozonation and rainwater harvesting (RWH) (Tarpani et al., 2021). Another study compared two potable water production techniques, a proposed SWRO plant, and a mine-affected water membrane treatment. Electricity causes most environmental impacts (Goga et al., 2019). A comparative study assessed how the future water demand of Iran can be secured through SWRO desalination plants powered by 100% renewable energy systems (RES) and estimated the cost of energy supply scenarios per m³ of drinking water in Iran. The authors suggested a combination of solar photovoltaics (PV) fixed-tilted, PV single-axis tracking, Wind, Battery, and Power-to-Gas (PtG) plants with a convincing price compared to the current fossil fuel-powered plants. The Levelized cost of water (LCOW) lies between 1.0 €/m³ and 3.5 €/m³, depending on available RES sources and transportation costs (Caldera et al., 2019). Also, other studies and assessments showed the impact of seawater desalination on Persian Gulf salinity in the present and future. The first inspected the stability of the current state to salinity agitation using a coupled Gulf-Atmosphere numerical climate. Continuous salinity perturbation showed that the equilibrium state, considered by approximate annual mean basin-average salinity of 40.5 g/kg, is stable, and the Gulf salinity under the present climate is resilient to the current rate of brine discharge. However, a changing climate and expansion of desalination capacity will likely affect the current stability in the future (Lee and Kaihatu, 2018; Sharifinia et al., 2019). LCA and mixed-integer linear programming were implemented to choose the optimum Intake type and compare centralized or decentralized RO plants for metropolitan water supply (Caldera et al., 2019; Shahabi et al., 2017).

In pervious study review, to assess the life cycle environmental impact of the SWRO technology to produce demineralized industrial water and the emission to water due to brine rejection have not been included in the inventory of other studies that have been found. Given that the Persian Gulf is the hotspot of brine discharge and accounts for almost 50% of 51.7 m³/yr of global brine rejection (Jones et al., 2019), the abovementioned concerns seem crucial to include the impacts of brine rejection in SWRO LCA studies. This study encompasses all input chemicals in detail, generated solid wastes, and brine rejection in the inventory.

This study aims to assess the life cycle environmental impact of SWRO desalination for potable and industrial water production. This objective can provide a baseline for decision-makers to evaluate the environmental impacts and hotspots and determine the improvement potential for future developments. This study is based on actual industrial data and could be compared with further studies or different methods of industrial water production. Given that the Persian Gulf is hyper-salinated and the inventory data are very detailed and comprehensive, different results are expected compared to routine seawater desalination units.

Section snippets

Methods

This LCA study comprises four phases, according to ISO 14040:2006 (ISO 2004). The first phase includes goal and scope definition. The second phase involved data collection and inventory analysis. In the third phase, the life cycle impact of the two products was assessed. In the fourth phase, the results are interpreted, including a sensitivity analysis, and discussed.

Life cycle environmental impacts

Outputs are analyzed based on the ReCiPe long-term hierarchical perspective (Huijbregts et al., 2017). The impacts of the defined hotspots could be minimized by implementing proper system management. The results of 18 impact categories for potable and industrial water are shown in Table 3. The impacts of industrial water are almost double the potable water in most categories.

Fig. 4 (a, b) demonstrates the contribution of inputs in 18 impact categories. Electricity and chemical consumption are

Conclusion

Life cycle assessment is implemented in SWRO as an increasingly growing water supply method in the Persian Gulf. Brine rejection is included in the inventory for the first time considering its consequences to the marine ecosystem. A comprehensive and detailed inventory covering brine rejection and all chemicals and wastes is prepared. LCA of demineralized industrial SWRO is implemented for the first time, which would be a baseline for future studies concerning the high amount of industrial

CRediT authorship contribution statement

Samaneh Fayyaz: Formal analysis, interpreted the results, Writing – original draft, and, designed the figures, All authors discussed the results and commented on the manuscript, All authors provided critical feedback and helped shape the research, analysis, and manuscript. Siavash Khadem Masjedi: Data curation, and, clarification of technical details, Writing – original draft, and, designed the figures, All authors discussed the results and commented on the manuscript, All authors provided

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgments

The authors greatly acknowledge the information regarding the SWRO system of an industrial plant provided in the south of Iran.

References (34)