Intensification and energy minimization of seawater reverse osmosis desalination through high-pH operation: Temperature dependency and second pass implications

TY - JOUR

T1 - Intensification and energy minimization of seawater reverse osmosis desalination through high-pH operation

T2 - Temperature dependency and second pass implications

AU - Segal, Hadas

AU - Birnhack, Liat

AU - Nir, Oded

AU - Lahav, Ori

N1 - Publisher Copyright: © 2018 Elsevier B.V.

PY - 2018/9

Y1 - 2018/9

N2 - Operation of seawater reverse-osmosis (RO) desalination using high flux membranes at pH > 9 was shown to be an energy-efficient approach for single-pass boron removal. This operational approach was previously studied only at 25 °C, however since RO desalination is highly temperature-dependent, the current work tested the high-pH approach throughout the typical temperature range of the Mediterranean Sea. Since total dissolved solids (TDS) removal in a high-flux-membranes single-pass is limited, the effect of applying a 2nd RO pass was also examined. Finally, the process cost was assessed at varying operational conditions. Results showed 1st pass permeate TDS to be ∼440, 290 and 200 mg/l at 54% recovery-ratio and 31, 25 and 15 °C, respectively. Boron removal was adequate (i.e. <0.4 mgB/l in permeate) at pH 9.5 throughout the temperature range. However, at 31 °C antiscalant had to be added to prevent Mg(OH)2 scaling. TDS and boron concentrations in the 2nd-pass permeate met the threshold limit (30 mg/l and 0.5 mgB/l) at 90% recovery ratio. The cost of applying the single-pass alternative process was lower by about $0.03/m3 permeate than the conventional alternative, for temperatures lower than 28 °C. The addition of a second pass increased the operational cost merely by a ∼$0.03/m3, making the described two-pass process competitive.

AB - Operation of seawater reverse-osmosis (RO) desalination using high flux membranes at pH > 9 was shown to be an energy-efficient approach for single-pass boron removal. This operational approach was previously studied only at 25 °C, however since RO desalination is highly temperature-dependent, the current work tested the high-pH approach throughout the typical temperature range of the Mediterranean Sea. Since total dissolved solids (TDS) removal in a high-flux-membranes single-pass is limited, the effect of applying a 2nd RO pass was also examined. Finally, the process cost was assessed at varying operational conditions. Results showed 1st pass permeate TDS to be ∼440, 290 and 200 mg/l at 54% recovery-ratio and 31, 25 and 15 °C, respectively. Boron removal was adequate (i.e. <0.4 mgB/l in permeate) at pH 9.5 throughout the temperature range. However, at 31 °C antiscalant had to be added to prevent Mg(OH)2 scaling. TDS and boron concentrations in the 2nd-pass permeate met the threshold limit (30 mg/l and 0.5 mgB/l) at 90% recovery ratio. The cost of applying the single-pass alternative process was lower by about $0.03/m3 permeate than the conventional alternative, for temperatures lower than 28 °C. The addition of a second pass increased the operational cost merely by a ∼$0.03/m3, making the described two-pass process competitive.

KW - Boron removal

KW - Low SEC

KW - Reverse osmosis

KW - Seawater desalination

KW - high-pH 1st pass

UR - http://www.scopus.com/inward/record.url?scp=85050231678&partnerID=8YFLogxK

U2 - 10.1016/j.cep.2018.07.009

DO - 10.1016/j.cep.2018.07.009

M3 - 文章

AN - SCOPUS:85050231678

VL - 131

SP - 84

EP - 91

JO - Chemical Engineering and Processing: Process Intensification

JF - Chemical Engineering and Processing: Process Intensification

SN - 0255-2701

ER -