title: Impact of elevated Ca(2+)/Mg(2+) concentrations of reverse osmosis membrane desalinated seawater on the stability of water pipe materials.
abstract: Hardness and alkalinity are known factors influencing the chemical stability of desalinated water. This study was carried out to investigate the effect of Ca(2+) and Mg(2+) on corrosion and/or scale formation on the surface of different water distribution pipe materials under tropical conditions. The corrosion rates of ductile iron, cast iron and cement-lined ductile iron coupons were examined in reverse osmosis (RO) membrane desalinated seawater which was remineralised using different concentrations of Ca(2+) and Mg(2+). The changes in water characteristics and the coupon corrosion rates were studied before and after the post-treatment. The corrosion mechanisms and corrosion products were examined using scanning electron microscope and X-ray diffraction, respectively. We found that the combination of Ca(2+) and Mg(2+) (60/40 mg/L as CaCO3) resulted in lower corrosion rates than all other treatments for the three types of pipe materials, suggesting that Ca(2+)/Mg(2+) combination improves the chemical stability of desalinated seawater rather than Ca(2+) only.
authors.affiliation: National University of Singapore, NUS Environment Research Institute, 5A Engineering Drive 1, T-Lab Building #02-01, Singapore 117411, Singapore.
authors.forename: Juan
authors.initials: J
authors.lastname: Liang
authors.affiliation: National University of Singapore, NUS Environment Research Institute, 5A Engineering Drive 1, T-Lab Building #02-01, Singapore 117411, Singapore.
authors.forename: Anqi
authors.initials: A
authors.lastname: Deng
authors.affiliation: Technology Department, the Public Utilities Board, 80/82 Toh Guan Road East, #C4-03, Singapore 60857, Singapore E-mail: xie_rongjing@pub.gov.sg.
authors.forename: Rongjing
authors.initials: R
authors.lastname: Xie
authors.affiliation: Technology Department, the Public Utilities Board, 80/82 Toh Guan Road East, #C4-03, Singapore 60857, Singapore E-mail: xie_rongjing@pub.gov.sg.
authors.forename: Mylene
authors.initials: M
authors.lastname: Gomez
authors.affiliation: National University of Singapore, NUS Environment Research Institute, 5A Engineering Drive 1, T-Lab Building #02-01, Singapore 117411, Singapore.
authors.forename: Jiangyong
authors.initials: J
authors.lastname: Hu
authors.affiliation: National University of Singapore, NUS Environment Research Institute, 5A Engineering Drive 1, T-Lab Building #02-01, Singapore 117411, Singapore.
authors.forename: Jufang
authors.initials: J
authors.lastname: Zhang
authors.affiliation: National University of Singapore, NUS Environment Research Institute, 5A Engineering Drive 1, T-Lab Building #02-01, Singapore 117411, Singapore.
authors.forename: Choon Nam
authors.initials: CN
authors.lastname: Ong
authors.affiliation: Department of Soil and Water Sciences, Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot 76100, Israel.
authors.forename: Avner
authors.initials: A
authors.lastname: Adin
mesh_terms: D002118:Calcium / Q000737:chemistry*; D003343:Corrosion; D005374:Filtration / Q000295:instrumentation; D007501:Iron / Q000737:chemistry*; D008274:Magnesium / Q000737:chemistry*; D008567:Membranes, Artificial; D008855:Microscopy, Electron, Scanning; D009995:Osmosis; D012623:Seawater / Q000737:chemistry*; D013499:Surface Properties; D018508:Water Purification / Q000379:methods*
chemical_list: D008567:Membranes, Artificial; D007501:Iron; D008274:Magnesium; D002118:Calcium