Improving Desalination Recovery Using Zero Discharge Desalination (ZDD): A Process Model for Evaluating Technical Feasibility

Abstract

Zero Discharge Desalination (ZDD) is a very-high-recovery hybrid desalination system, typically comprised of a primary desalter (such as reverse osmosis (RO) or nanofiltration (NF)) and electrodialysis metathesis (EDM). The EDM acts as a “kidney” by removing troublesome salts from the concentrate of the primary desalter, which allows for additional recovery of potable water. A mathematical model was developed to simulate ZDD system performance using mass balance, desalination design equations, and experimental data. Model results confirm that ZDD can achieve >97% system recovery for brackish water with (a) a feed total dissolved solids (TDS) concentration of <3 g/L; (b) relatively high fractions of multivalent ions (e.g., calcium and sulfate mass concentrations of >60% of the TDS); and (c) a silica content of <40 mg/L. Furthermore, model results indicate that the required ZDD specific energy consumption (a) increases by 0.77 kWh per 1 g/L of feed TDS; (b) increases with lower permeate TDS, especially below 500 mg/L; and (c) generally decreases with higher recovery on the primary desalter (e.g., RO or NF). ZDD system recovery generally decreases by ∼1% per 1 g/L of feed TDS. Higher TDS feedwater (e.g., 3.5 to 5 g/L) limits ZDD system recoveries to 94% to 90%, respectively.

Evaluation of Electrodialysis Desalination Performance of Novel Bioinspired and Conventional Ion Exchange Membranes with Sodium Chloride Feed Solutions

“…LCD and areal resistance results were not achieved for feed solution concentration of 35 and 100 g/L, because the maximum working capacity of the power supply (30 V, 5 A) was reached before observing LCD (thus, results are not shown for 35 and 100 g/L feed solution in Figure 3 ). The LCD ranged from 50 to 600 A/m 2 , increasing with salinity and increasing with superficial velocity ( Figure 3 a,c), which is consistent with other studies [ 39 , 40 , 41 ]. The voltage application required to achieve LCD ranged from 0.9 to 1.4 Volts per cell pair, the corresponding areal resistance per cell pair at LCD ranged from 22 to 183 Ω cm 2 ( Figure 3 b,d), and the limiting polarization parameter value ranged from 0.66 to 5.28 A/m 2 per meq/L ( Figure 3 e).…”

“…LCD was determined using the voltage and current data that were recorded during the experiments. Theoretically, there are different approaches employed to determine and compare the LCD [ 41 ]; firstly, the “Shoulder” method was used, which involves plotting stack voltage on the abscissa and current density ( i ) on the ordinate ( Figure 2 a), and secondly, the “Cowan–Brown” method was used, which involves plotting inverse of stack’s current density (1/ i ) on the abscissa and stack’s areal electrical resistance per cell-pair on the ordinate ( Figure 2 b) [ 39 , 40 , 41 ]. As shown in Figure 2 a,b, the LCD was the point where two lines (blue and red) intersected in both methods [ 41 ].…”

Electrodialysis Applications in Wastewater Treatment for Environmental Protection and Resources Recovery: A Systematic Review on Progress and Perspectives

“…The complete salt production scheme (SWRO-ED-crystallizer) was competitive with the SWRO desalination only in some Middle-East countries, where the salt price is higher than 104.5 $/ton. EDM of BWRO [507] or SWRO [41] brine was proposed. The complete conceptual scheme of SWRO-EDM is depicted in Figure 28.…”

“…EDM of BWRO [ 507 ] or SWRO [ 41 ] brine was proposed. The complete conceptual scheme of SWRO-EDM is depicted in Figure 28 .…”

Electrodialysis Metathesis (EDM) Desalination for the Effective Removal of Chloride and Nitrate from Tobacco Extract: The Effect of Membrane Type

“…Therefore, ED-based technologies must be designed to stimulate the separation and pre-concentration of typical brine-containing scaling components. Electrodialysis metathesis (EDM) systems represent a novel reactor based on ED processes, with the remarkable ability to recombine and concentrate ions simultaneously [ 31 ]. An EDM stack is structurally composed of two pairs of ion exchange membranes and two pairs of spacers with four plane channels; such systems can also transform sparingly soluble salts into highly soluble liquid salts.…”