Abbas Ghassemi

Characterization of reverse osmosis and nanofiltration membranes: effects of operating conditions and specific ion rejection

AbstractReverse osmosis (RO) and nanofiltration (NF) are two of the most commonly used technologies for desalinating brackish and saline waters to provide potable water. However, there is still lack of a thorough comparison between these two methods providing the better option in different conditions. Therefore, in this paper, salt rejection and the effects of operation conditions on the performance of RO and NF systems are compared. Inlet water conductivity, inlet pH, permeate flow rate, temperature, and recovery rate are used as variable operating conditions, and permeate conductivity is considered as the target of comparison as it reflects the level of salts in product water. Five combinations of inland brackish water, drawn from wells located at the experimental site, were applied as different feed waters and five distinct types of membranes, three RO and two NF, were studied using pilot-scale equipment. To allow meaningful comparison among RO and NF membrane performances, identical hydrodynamic opera...

Effects of operating conditions on ion removal from brackish water using a pilot-scale electrodialysis reversal system

AbstractUnderstanding the effects of operating factors on ion removal in the electrodialysis/electrodialysis reversal (ED/EDR) process can significantly benefit industrial applications, enabling process optimization through different combinations of operational factors. Several studies have shown the effects of specific operating factors on ion removal, and it has been established that superficial velocity influences ion removal. However, previous studies have yielded mixed results on whether increases in superficial velocity increase or decrease ion removal; also, since previous studies are based on laboratory-scale ED systems, the results may not be fully applicable to full-scale desalination due to differences in system characteristics such as membrane area, flow path, and degree of superficial velocity’s effect on ion removal. Therefore, this experimental study employs a pilot-scale EDR system that is very similar to a full-scale system in order to explore the effects of applied voltage, superficial v...

High-recovery electrodialysis reversal for the desalination of inland brackish waters

AbstractSince the inland disposal of large volumes of desalination concentrate is environmentally and financially impractical, a high-recovery desalination design is required to reduce concentrate volume. In practical applications, recovery is limited by scale formation from minimally soluble salts, which acids and antiscalant compounds can inhibit only temporarily. Therefore, the risk of scale formation, which is governed by the system’s electrochemical behavior, determines the high-recovery potential of desalination technologies. In this research, high recovery was investigated using a pilot-scale electrodialysis reversal (EDR) system and natural feedwaters from a deep aquifer at the Brackish Groundwater National Desalination Research Facility in Alamogordo, NM. Experiments were performed to identify the maximum permissible CaSO4 saturation levels during long-term, continuous operation with antiscalant dosing. The results indicated that EDR has enormous potential for treating CaSO4-rich inland brackish ...

A prediction model of mass transfer through an electrodialysis cell

AbstractThe purpose of this work is to develop a mass transfer model that incorporates all relevant factors—migration, diffusion, and convection—to predict ion transfer in electrodialysis cells more completely than conventional models, which neglect convection. As a demonstration of this approach, the study develops a three-dimensional model that incorporates the factor of convection to predict NaCl mass transport through a rectangular electrodialysis cell. The equations used in the model—the complete Navier–Stokes, continuity, and steady-state Nernst–Planck equations—are solved by the finite difference numerical method in the particular control volumes. The equations in the dilute chamber are numerically solved using techniques from computational fluid dynamics (CFD). In order to evaluate the reliability and accuracy of the model, the results are compared with theory as calculated by the Nernst–Planck equation. We discovered that the developed model is capable of predicting the velocity distribution, sep...

Complete sustainability in electrodialysis reversal desalination: reusing tertiary-treated municipal wastewater as feed in the concentrate stream and electrodes rinsing water

abstract Electrodialysis reversal (EDR) has been innovative based on unplanned indirect potable water reuse to replace the same amount of raw water withdrawn from brackish (sea) water source and conserving 15–20% of freshwater by reusing tertiary-treated municipal wastewater (TTMWW) as feed in the concentrate and electrode stream while brackish groundwater (sea water) remains feed into dilute stream. By substituting TTMWW, our analysis shows the resulting total dissolved solid (TDS) concentration in the waste stream lower than that in the original source of brackish groundwater (sea water) which fed into dilute stream. The waste from EDR system with TTMWW as feed in concentrate and electrode streams can be recharged back into groundwater (sea water) source which do not add the TDS concentration. In fact, it reduces the TDS concentration by dilution. New significant findings are: (1) 17,500 m3/d of freshwater could be saved with the data from 1990; the saving would be increased in 2011 and much more in fut...

Electrodialysis reversal desalination: monographs for the design parameters

Abstract Electrodialysis reversal (EDR) is known for its excellence to desalt Ca2+ and dominated brackish groundwater with a higher water recovery rate, an elevated silt density index (SDI 6-12), potential for biofouling, hard-to-treat, high hardness, and lower salinity feed waters with the ranges of 200–5000 mg/L TDS. The power index is the only currently available design and evaluating parameter for the EDR process; however, power index is only valid for the same total dissolved solid (TDS) concentrations of feed and product water. Since, ED/EDR is capable of treating a variable source of water quality while producing a consistent finished water quality, comprehensive design and evaluating parameters are required, identified and proposed in this study. The quantities of the design parameters were developed from 52 sets of literature experimental data that have 10 different types of feed water characteristics. Another one set of literature experimental data was used to validate the values of developed pa...

Energy usage and carbon dioxide emission saving in desalination by using desalination concentrate and wastes in microalgae production

AbstractEnergy usage and CO2 emission between traditional electrodialysis reversal (EDR) and innovative EDR desalinations were compared. The difference between traditional and innovative EDR desalination depended on which concentrate treatment was employed. Traditional EDR desalination consists of electrodialysis as concentrate treatment, while innovative EDR desalination consists of Dunaliella salina production as concentrate treatment. Microalgae species D. salina and Arthrospira (Spirulina) platensis were cultured in used bottles (3.7 L) as reactors and using desalination concentrate and supernatant from anaerobic digested sludge (SADS) as growth medium and nutrients. D. salina was grown in reactors D1, D2, D3, and D4. Spirulina platensis was in S1, S2, S3, and S4. SADS was supplied to reactors D1, D2, S1, and S2 as nutrient. Bold’s Basal Medium was supplied to reactors D3 and D4 while F2 was supplied to reactors S3 and S4 as nutrient. Conductivity of desalination concentrates used in reactors D1 and D...

A generic stoichiometric equation for microalgae-microorganism nexus by using clarified domestic wastewater as growth medium

AbstractStoichiometric equations for microalgae–microorganism nexus culture were established by using 18 sets of experimental data from the literature where clarified domestic wastewater (CDWW) was used as a growth media. The best correlations between observed and calculated coefficients in the equations were 0.908, 0.878, 0.838, and 0.849 for reactors R1, R2, R3, and the sum of three reactors, respectively. Then, each stoichiometric equation was generalized to quantitatively describe the reactions in each set of data for 18 different experimental conditions. By analysis, the most and second most sensitive limiting parameters were identified from the 18 stoichiometric equations. The formulas and equations were further upgraded to a generic form for a general organic growth medium (CaHbOcNdPf). Microalgae–microorganism nexus was established by using the developed coefficients to depict the limited and balanced reactions. The study showed that nitrogen and phosphorus are required as additives in CDWW in ord...

Brackish water desalination using electrodialysis: predictive mass transfer and concentration distribution model along the electrodialyzer

This study employs theory and experimental data from a laboratory-scale electrodialyzer to predict sodium chloride (NaCl) mass transport and concentration distribution along the electrodialyzer as a function of feed concentration, feed flow rate, applied voltage, and pressure. Moreover, a model was developed to predict the ion removal as a function of driving forces through solving the complete Navier-Stokes, continuity, and steady state Nernst-Planck equations by the finite difference numerical method. The findings of the experiments confirmed that concentration distributions are nonlinear along both the dilute and concentrate compartments. The results also demonstrated that increases in pressure and feed flow rate have a negative effect on salt removal, linear and nonlinear for pressure and flow rate, respectively. In the investigated ranges, higher voltage increased salt removal at a constant feed concentration.

The hysteretic behavior in adsorption isotherm of microporous adsorbents: A case study on Zn(NH3)(CO3)

E extraction (EME) is a sample preparation technique in pharmaceutical, chemical, clinical and environmental analysis. This technique uses electro-migration across artificial liquid membranes for selective extraction of analytes and sample enrichment from complex matrices. This method has many advantages such as simplicity, rapid, low-cost, low LOD, high pre-concentration factor and high recovery. In the present work, simultaneous pre-concentration and determination of two basic drugs namely metoclopramide (MCP) and ondansetron (OSN) were studied using EME as a suitable extraction method, followed with capillary electrophoresis (CE) using ultraviolet (UV) detection as separation technique. The drugs were extracted from 4 ml sample solutions, through a supported liquid membrane (SLM) consisting 2-nitrophenyloctylether (NPOE) impregnated in the walls of a polypropylene hollow fiber, and into a 20 mL acidic aqueous acceptor solution resent inside the lumen of the hollow fiber with a potential difference applied over the SLM. The variables of interest, such as chemical composition of the organic liquid membrane, stirring speed, extraction time and voltage, pH of donor and acceptor phases and salt effect in the EME process were investigated and optimized. Under optimal conditions NPOE as SLM, stirring rate of 1000 rpm, 200 V potential differences, 20 min as the extraction time, acceptor phase HCl (pH 1.0) and donor phase HCl (pH 1.5). After the microextraction process, the extracts were analyzed by CE with optimum conditions phosphate running buffer (pH 2.0), applied voltage of 20 kV and 25°C. Under the optimum conditions, limits of detection (LOD) and quantification (LOQ) for MCP and OSN were 2.31-2.68 and 7.72-8.91 ng mL-1 respectively. Pre-concentration factor and RSD for five replicates of each drug were calculated to be 200 and 4.06-3.93 respectively. Finally, the applicability of this method was studied by the extraction and determination of these drugs in urine samples with recovery percentages of 87–92%.The modern theory of phase transitions cannot explain the results of many experiments of interphase mass transfer. One reason for this is the assumption that during crystallization the solution is in the metastable state. The decomposition of the solution occurs by binodal scenario in this case. Crystallization nuclei form and grow in solution. The purpose of this study to show that in many cases the solution during crystallization is in an unstable state. The unstable condition leads to decomposition the solution by spinodal scenario