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Engineering    2016, Vol. 2 Issue (4) : 460 -469
Research |
Sustainable Application of a Novel Water Cycle Using Seawater for Toilet Flushing
Xiaoming Liu1,2,3,Ji Dai1,2,3,Di Wu1,2,3,Feng Jiang4,Guanghao Chen1,2,3,Ho-Kwong Chui1,3,Mark C. M. van Loosdrecht5,()
1. Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Hong Kong, China
2. Water Technology Center, The Hong Kong University of Science and Technology, Hong Kong, China
3. Chinese National Engineering Research Center for Control and Treatment of Heavy Metal Pollution (Hong Kong Branch), The Hong Kong University of Science and Technology, Hong Kong, China
4. School of Chemistry and Environment, South China Normal University, Guangzhou 510006, China
5. Department of Biotechnology, Delft University of Technology, Delft 2629 HZ, the Netherlands

Global water security is a severe issue that threatens human health and well-being. Finding sustainable alternative water resources has become a matter of great urgency. For coastal urban areas, desalinated seawater could serve as a freshwater supply. However, since 20%–30% of the water supply is used for flushing waste from the city, seawater with simple treatment could also partly replace the use of freshwater. In this work, the freshwater saving potential and environmental impacts of the urban water system (water-wastewater closed loop) adopting seawater desalination, seawater for toilet flushing (SWTF), or reclaimed water for toilet flushing (RWTF) are compared with those of a conventional freshwater system, through a life-cycle assessment and sensitivity analysis. The potential applications of these processes are also assessed. The results support the environmental sustainability of the SWTF approach, but its potential application depends on the coastal distance and effective population density of a city. Developed coastal cities with an effective population density exceeding 3000 persons·km–2 and located less than 30?km from the seashore (for the main pipe supplying seawater to the city) would benefit from applying SWTF, regardless of other impact parameters. By further applying the sulfate reduction, autotrophic denitrification, and nitrification integrated (SANI) process for wastewater treatment, the maximum distance from the seashore can be extended to 60?km. Considering that most modern urbanized cities fulfill these criteria, the next generation of water supply systems could consist of a freshwater supply coupled with a seawater supply for sustainable urban development.

Keywords Alternative water resources      Seawater toilet flushing      SANI      Urban water system      Life-cycle assessment     
Corresponding Authors: Mark C. M. van Loosdrecht   
Just Accepted Date: 21 December 2016   Online First Date: 23 December 2016    Issue Date: 28 December 2016
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Xiaoming Liu
Ji Dai
Di Wu
Feng Jiang
Guanghao Chen
Ho-Kwong Chui
Mark C. M. van Loosdrecht
Cite this article:   
Xiaoming Liu,Ji Dai,Di Wu, et al. Sustainable Application of a Novel Water Cycle Using Seawater for Toilet Flushing[J]. Engineering, 2016, 2(4): 460 -469 .
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1   Postel SL. Entering an era of water scarcity: the challenges ahead. Ecol Appl 2000;10(4): 941–8
doi: 10.1890/1051-0761(2000)010[0941:EAEOWS]2.0.CO;2
2   Vörösmarty CJ, McIntyre PB, Gessner MO, Dudgeon D, Prusevich A, Green P, Global threats to human water security and river biodiversity. Nature 2010;467(7315):555–61
doi: 10.1038/nature09440
3   Hoekstra AY, Mekonnen MM, Chapagain AK, Mathews RE, Richter BD. Global monthly water scarcity: blue water footprints versus blue water availability. PLoS One 2012;7(2):e32688
doi: 10.1371/journal.pone.0032688
4   Grant SB, Saphores JD, Feldman DL, Hamilton AJ, Fletcher TD, Cook PL, Taking the “waste” out of “wastewater” for human water security and ecosystem sustainability. Science 2012;337(6095):681–6
doi: 10.1126/science.1216852
5   Shannon MA, Bohn PW, Elimelech M, Georgiadis JG, Mariñas BJ, Mayes AM. Science and technology for water purification in the coming decades. Nature 2008;452(7185):301–10
doi: 10.1038/nature06599
6   Tal A. Seeking sustainability: Israel’s evolving water management strategy. Science 2006;313(5790):1081–4
doi: 10.1126/science.1126011
7   Hinrichsen D. Coastal waters of the world: trends, threats, and strategie. Washington, DC: Island Press; 1998.
8   Chen G, Chui HK, Wong CL, Tang TW, Lu H, Jiang F, An innovative triple water supply system and a novel SANI® process to alleviate water shortage and pollution problem for water-scarce coastal areas in China. J Water Sustain 2012;2(2):121–9.
9   Leung RW, Li DC, Yu WK, Chui HK, Lee TO, van Loosdrecht MC, Integration of seawater and grey water reuse to maximize alternative water resource for coastal areas: the case of the Hong Kong International Airport. Water Sci Technol 2012;65(3):410–7
doi: 10.2166/wst.2012.768
10   Wang J, Shi M, Lu H, Wu D, Shao MF, Zhang T, Microbial community of sulfate-reducing up-flow sludge bed in the SANI® process for saline sewage treatment. Appl Microbiol Biotechnol 2011;90(6):2015–25
doi: 10.1007/s00253-011-3217-3
11   Lu H, Ekama GA, Wu D, Feng J, van Loosdrecht MC, Chen GH. SANI® process realizes sustainable saline sewage treatment: steady state model-based evaluation of the pilot-scale trial of the process. Water Res 2012;46(2):475–90
doi: 10.1016/j.watres.2011.11.031
12   Lu H, Wu D, Jiang F, Ekama GA, van Loosdrecht MC, Chen GH. The demonstration of a novel sulfur cycle-based wastewater treatment process: sulfate reduction, autotrophic denitrification, and nitrification integrated (SANI®) biological nitrogen removal process. Biotechnol Bioeng 2012;109(11):2778–89
doi: 10.1002/bit.24540
13   Wang J, Lu H, Chen GH, Lau GN, Tsang WL, van Loosdrecht MC. A novel sulfate reduction, autotrophic denitrification, nitrification integrated (SANI) process for saline wastewater treatment. Water Res 2009;43(9):2363–72
doi: 10.1016/j.watres.2009.02.037
14   Lu H, Wang J, Li S, Chen GH, van Loosdrecht MC, Ekama GA. Steady-state model-based evaluation of sulfate reduction, autotrophic denitrification and nitrification integrated (SANI) process. Water Res 2009;43(14):3613–21
doi: 10.1016/j.watres.2009.05.013
15   Lu H, Wu D, Tang DT, Chen GH, van Loosdrecht MC, Ekama G. Pilot scale evaluation of SANI process for sludge minimization and greenhouse gas reduction in saline sewage treatment. Water Sci Technol 2011;63(10):2149–54
doi: 10.2166/wst.2011.342
16   Wu D, Ekama GA, Chui H-K, Wang B, Cui Y-X, Hao T-W, Large-scale demonstration of the sulfate reduction autotrophic denitrification nitrification integrated (SANI®) process in saline sewage treatment. Water Res 2016;100:496–507
doi: 10.1016/j.watres.2016.05.052
17   Finnveden G, Hauschild MZ, Ekvall T, Guinée J, Heijungs R, Hellweg S, Recent developments in Life Cycle Assessment. J Environ Manage 2009;91(1):1–21
doi: 10.1016/j.jenvman.2009.06.018
18   International Organization for Standardization.ISO 14040:2006 Environmental management─life cycle assessment─principles and framework. 2nd ed. Geneva: International Standards Organisation; 2006.
19   Chanan A, Woods P. Introducing total water cycle management in Sydney: a Kogarah Council initiative. Desalination 2006;187(1–3):11–6
doi: 10.1016/j.desal.2005.04.063
20   Renzoni R, Germain A. Life cycle assessment of water: from the pumping station to the wastewater treatment plant. Int J Life Cycle Assess 2007;12(2): 118–26
doi: 10.1065/lca2005.12.243
21   Amores MJ, Meneses M, Pasqualino J, Antón A, Castells F. Environmental assessment of urban water cycle on Mediterranean conditions by LCA approach. J Cleaner Prod 2013;43:84–92
doi: 10.1016/j.jclepro.2012.12.033
22   Muñoz I, Fernández-Alba AR. Reducing the environmental impacts of reverse osmosis desalination by using brackish groundwater resources. Water Res 2008;42(3):801–11
doi: 10.1016/j.watres.2007.08.021
23   Li Y, Xiong W, Zhang W, Wang C, Wang P. Life cycle assessment of water supply alternatives in water-receiving areas of the South-to-North Water Diversion Project in China. Water Res 2016;89:9–19
doi: 10.1016/j.watres.2015.11.030
24   Barjoveanu G, Comandaru IM, Rodriguez-Garcia G, Hospido A, Teodosiu C. Evaluation of water services system through LCA. A case study for Iasi City, Romania. Int J Life Cycle Assess 2014;19(2):449–62
doi: 10.1007/s11367-013-0635-8
25   Raluy RG, Serra L, Uche J, Valero A. Life cycle assessment of water production technologies─part 2: reverse osmosis desalination versus the Ebro River water transfer. Int J Life Cycle Assess 2005;10(5):346–54
doi: 10.1065/lca2004.09.179.2
26   Hospido A, Moreira T, Martín M, Rigola M, Feijoo G. Environmental evaluation of different treatment processes for sludge from urban wastewater treatments: anaerobic digestion versus thermal processes. Int J Life Cycle Assess 2005;10(5):336–45
doi: 10.1065/lca2005.05.210
27   Lloyd SM, Ries R. Characterizing, propagating, and analyzing uncertainty in life-cycle assessment: a survey of quantitative approaches. J Ind Ecol 2007;11(1):161–79
doi: 10.1162/jiec.2007.1136
28   Loubet P, Roux P, Loiseau E, Bellon-Maurel V. Life cycle assessments of urban water systems: a comparative analysis of selected peer-reviewed literature. Water Res 2014;67:187–202
doi: 10.1016/j.watres.2014.08.048
29   Friedrich E, Pillay S, Buckley CA. Environmental life cycle assessments for water treatment processes─a South African case study of an urban water cycle. Water SA 2009;35(1):73–84.
30   Seto KC, Güneralp B, Hutyra LR. Global forecasts of urban expansion to 2030 and direct impacts on biodiversity and carbon pools. Proc Natl Acad Sci USA 2012;109(40):16083–8
doi: 10.1073/pnas.1211658109
31   Lemos D, Dias AC, Gabarrell X, Arroja L. Environmental assessment of an urban water system. J Cleaner Prod 2013;54:157–65
doi: 10.1016/j.jclepro.2013.04.029
32   Godskesen B, Hauschild M, Rygaard M, Zambrano K, Albrechtsen HJ. Life-cycle and freshwater withdrawal impact assessment of water supply technologies. Water Res 2013;47(7):2363–74
doi: 10.1016/j.watres.2013.02.005
33   Schoen ME, Xue X, Hawkins TR, Ashbolt NJ. Comparative human health risk analysis of coastal community water and waste service options. Environ Sci Technol 2014;48(16):9728–36
doi: 10.1021/es501262p
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