Role of phosphate and humic substances in controlling calcium carbonate scaling in a groundwater reverse osmosis system
AuthorsMangal, M. Nasir
Salinas-Rodriguez, Sergio G.
Yangali-Quintanilla, Victor A.
Schippers, Jan C.
Van Der Meer, Walter G.J.
Kennedy, Maria D.
KAUST DepartmentBiological and Environmental Science and Engineering (BESE) Division
Water Desalination and Reuse Research Center (WDRC)
Online Publication Date2021-05-14
Print Publication Date2021-08
Permanent link to this recordhttp://hdl.handle.net/10754/669409
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AbstractThe role of phosphate and humic substances (HS) in preventing calcium carbonate scaling and their impact on antiscalant dose was investigated for a reverse osmosis (RO) system treating anaerobic groundwater (GW) (containing 2.1 mg/L orthophosphate and 6-8 mg/L HS). Experiments were conducted with the RO unit (treating anaerobic GW), and with a once-through lab-scale RO system (operating with artificial feedwater). Additionally, (batch) induction time (IT) measurements were performed with, i) real RO concentrate, and ii) artificial RO concentrates in the presence and absence of phosphate and HS. It was found that at 80% recovery (Langelier saturation index (LSI) 1.7), calcium carbonate scaling did not occur in the RO unit when the antiscalant dose was lowered from 2.2 mg/L (supplier's recommended dose) to 0 mg/L. The IT of the real RO concentrate, without antiscalant, was longer than 168 h, while, at the same supersaturation level, the IT of the artificial concentrate was approximately 1 h. The IT of the artificial concentrate increased to 168 h with the addition of 10 mg/L of phosphate, humic acid (HA), and fulvic acid (FA). Furthermore, in the lab-scale RO tests, the normalized permeability (Kw) of the membrane decreased by 20% in 2 h period when fed with artificial concentrate of 80% recovery containing no phosphate, whereas, with phosphate, no decrease in Kw was observed in 10 h period. These results indicate that phosphate and HS present in the GW prevented calcium carbonate scaling in the RO unit and reduced the use of commercial (synthetic) antiscalants.
CitationMangal, M. N., Salinas-Rodriguez, S. G., Blankert, B., Yangali-Quintanilla, V. A., Schippers, J. C., van der Meer, W. G. J., & Kennedy, M. D. (2021). Role of phosphate and humic substances in controlling calcium carbonate scaling in a groundwater reverse osmosis system. Journal of Environmental Chemical Engineering, 9(4), 105651. doi:10.1016/j.jece.2021.105651
SponsorsThis study was funded by Oasen Drinkwater (based in the Netherlands) and Grundfos Holding A/S (based in Denmark).
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