کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
150965 456460 2011 8 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Selective separation of seawater Mg2+ ions for use in downstream water treatment processes
موضوعات مرتبط
مهندسی و علوم پایه مهندسی شیمی مهندسی شیمی (عمومی)
پیش نمایش صفحه اول مقاله
Selective separation of seawater Mg2+ ions for use in downstream water treatment processes
چکیده انگلیسی

A nanofiltration-based method is presented for selectively separating soluble Mg(II) species from seawater, with the aim of using the Mg-loaded brine for either enriching desalinated water with magnesium ions or for enhancing precipitation of struvite from wastewater steams. Two 2.4″ commercial NF membranes were tested under varying operational conditions. The membrane that was chosen for further investigation (DS-5 DL, Osmonics) showed lower Cl:Mg and Na:Mg concentration ratios in the brine, and improved performance (with respect to the investigated process) at high recovery values. Since the addition of antiscalants was perceived detrimental to the downstream uses of the brine, the aquatic chemistry program PHREEQC was used to simulate the critical (highest) recovery values at which no CaSO4 would precipitate, assuming two concentration polarization factors. To prevent CaCO3 precipitation at the critical recovery values a theoretical calculation was performed (PHREEQC) to determine the required strong acid dosages to the raw seawater. Using the DS-5 DL membrane at 64% recovery, the attained Mg(II) concentration in the brine was 3500 mg/l. Therefore, for attaining 12.15 mg Mg/l of desalinated water the brine should be dosed to the water at a 1:288 ratio, resulting in additional concentrations of 32.5 mg SO4−2/l, 89.3 mg Cl−/l, 39.4 mg Na+/l, 3.3 mg Ca+2/l, and 0.01 mg B/l. The overall cost of the proposed process was estimated at 0.00098 $/m3 product water, i.e. approximately five times lower than two assessed alternative processes and more than one order of magnitude cheaper than implementing direct dissolution of chemicals, using either MgCl2 or MgSO4.


► We present a nanofiltration-based method for selective Mg2+separation from seawater.
► Nanofiltration brine can supply cheap Mg2+ to desalination plants product water.
► Nanofiltration brine can supply cheap Mg2+ for struvite recovery from wastewater.
► Cost of Mg2+ supply using the method is ∼20% of cost of closest alternative.
► 1 meqMg/l supplied to desalinated water adds ∼90 mgCl−/l, and ∼40 mgNa+/l.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Chemical Engineering Journal - Volume 175, 15 November 2011, Pages 136–143
نویسندگان
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