Bipolar Membrane Electrodialysis Research Articles

Case Study of Continuous Itaconic Acid Fermentation by Aspergillus Terreus in a Bench-Scale Bioreactor

Itaconic acid (IA) is a highly important bioproduct. The traditional biotechnological production of organic acids generates large quantities of biomass and water streams as waste. Bipolar membrane electrodialysis is a suitable technique for directly recovering IA from clarified fermentation broth whereby itaconic acid is separated without chemical loading. As a result, the remaining diluate stream can be reintroduced into the fermentation process. This membrane operation can be integrated into a continuous fermentation process in order to carry out the process using a high glucose concentration in the effluent, opening up new possibilities for the implementation of continuous itaconic acid fermentation. In this study, a possible highly successful implementation of this technique is presented. The applied gentle stirring technique as well as the low dilution rate of 0.007 s-1 is necessary to be complemented by highly efficient oxygenation, thereby promoting itaconic acid generation. With an inlet supplying pure oxygen gas, the acid accumulated and an average of 30.1 g·L-1 titer of IA was achieved in the effluent. The volumetric oxygen uptake rate was monitored during the fermentation which fluctuated from 40-88% so further investigation of this may be worthwhile in the future.

Bipolar membrane electrodialysis integration into the biotechnological production of itaconic acid: A proof-of-concept study

Itaconic acid is a promising biobased organic acid that can be industrially produced in an eco-friendly way by aerobic fungal fermentation. It has many applications, e.g. in biopolymers, and has the potential to help replace or facilitate the green production of other similar but fossil-based chemicals. Nowadays, its production costs are still relatively high, partly due to the multistep product recovery process from the fermentation broth. In this study, a reduced number of downstream processes were evaluated to recover itaconic acid from model and real fermentation effluents. To the best of our knowledge, this is the first time the whole procedure is presented from the substrates to the solid and pure product, including fermentation, electrodialysis with bipolar membrane, evaporation and optimized crystallization. Based on the fermentation temperature and elevated pH, a synergistic effect was observed that intensified certain mass transfer mechanisms. Consequently, a significant amount of water (400 cm3) and itaconic acid (15 g) was transported into the alkaline concentrate. Moreover, novel outcomes about the condition, decolorization and process enhancements of the membrane (product recovery: 65–80 %, current efficiency: 42–76 %, product purity: 99 %) were recorded. Based on the results, our group is one step closer to the final concept of a continuously operated fermentation-electrodialysis integrated system.

Ion Transport Behavior in Bipolar Membrane Electrodialysis: Role of Anions

Ion Transport Behavior in Bipolar Membrane Electrodialysis: Role of Anions

Bipolar membrane electrodialysis for sustainable utilization of inorganic salts from the reverse osmosis concentration of real landfill leachate

Developing an effective resource utilization method for landfill leachate reverse osmosis concentrate (LLRC) remains a challenge because of the high concentrations of inorganic salts and refractory organic compounds. This study applied a bipolar membrane electrodialysis (BMED) to separate inorganic salts from real LLRC while simultaneously reclaiming inorganic acids and bases. The performance of BMED was affected by operating parameters, such as operating voltage, membrane surface flow velocity, and initial acid-base concentration. With optimized operating parameters, the reclaimed acid-base concentrations, desalination rate, and current efficiency were higher with less energy consumption. Ultimately, 0.41 mol/L acids and 0.40 mol/L bases were reclaimed from LLRC. The reclaimed acids contained 88 wt% HCl and 12 wt% HNO3. The reclaimed bases were 52 wt% NaOH and 45 wt% KOH. Furthermore, the concentrations of arsenic and heavy metals were low enough to safely utilize reclaimed products. The electromigration of organic compounds was controlled by protonation. After excluding the fixed costs, the net profit of 1 m3 LLRC treatment by BMED was $27.630, which showed remarkable economic feasibility. Our research offers a new strategy to realize sustainable utilization of inorganic salts from LLRC.

Separation of lithium chloride from ammonium chloride by an electrodialysis-based integrated process

Li+ and NH4+ have the same charge, valence, and similar ionic hydration radii. Hence, it is challenging to separate them through individual electrodialysis. Herein, an electrodialysis (ED)-based integrated process is proposed to separate Li+ from the mixed solution of LiCl and NH4Cl and simultaneously generate a concentrated LiOH solution. First, bipolar membrane electrodialysis (BMED) converts the mixed solution into the alkali solution of LiOH and NH3·H2O. The BMED performance was investigated by varying the operating parameters. The results show that the BMED membrane stack with the BP-A-C configuration performs better than the one with the BP-C configuration. A solution of 2.16 mmol/L LiOH and 0.05 mol/L NH3·H2O, selected as the initial alkali solution for the alkali tank, can reduce the energy consumption from 88.51 to 83.45 kW·h/kg, and improve the current efficiency from 53.45% to 56.69% slightly. Reducing the initial volume ratio of the alkali solution to the feed can concentrate the generated alkali solution and increase the LiOH conversion ratio simultaneously. Furthermore, reducing the initial feed concentration can efficiently improve the BMED performance. A maximum LiOH conversion ratio of 97.10% can be achieved in the BMED process. Second, ammonia removal with direct air stripping (AR-DAS) process is performed on the mixed alkali solution of LiOH and NH3·H2O to remove the ammonia and obtain the pure LiOH solution. The results show an ammonia removal ratio of more than 99%. Third, conventional electrodialysis (CED) concentrates the LiOH solution. Effects of the applied voltages and initial LiOH solution concentrations on the CED performance were investigated. The results show that a higher applied voltage increases energy consumption, while a higher initial LiOH solution concentration improves the LiOH concentration ratio. A maximum LiOH concentration ratio of 2.19 can be achieved in the CED process. Moreover, through analysis, the final solid products, generated by evaporation and crystallization, are LiOH·H2O crystals with the purity of 94.3 ± 3.56%. This work suggests that the ED-based integrated process is a highly effective approach to separating the mixed salt solutions of Li+ and NH4+.

Ionic resource recovery for carbon neutral papermaking wastewater reclamation by a chemical self-sufficiency zero liquid discharge system

Papermaking industry discharges large quantities of wastewater and waste gas, whose treatment is limited by extra chemicals requirements, insufficient resource recovery and high energy consumption. Herein, a chemical self-sufficiency zero liquid discharge (ZLD) system, which integrates nanofiltration, bipolar membrane electrodialysis and membrane contactor (NF-BMED-MC), is designed for the resource recovery from wastewater and waste gas. The key features of this system include: 1) recovery of NaCl from pretreated papermaking wastewater by NF, 2) HCl/NaOH generation and fresh water recovery by BMED, and 3) CO2 capture and NaOH/Na2CO3 generation by MC. This integrated system shows great synergy. By precipitating hardness ions in papermaking wastewater and NF concentrate with NaOH/Na2CO3, the inorganic scaling on NF membrane is mitigated. Moreover, the NF-BMED-MC system with high stability can simultaneously achieve efficient CO2 removal and sustainable recovery of fresh water and high-purity resources (NaCl, Na2SO4, NaOH and HCl) from wastewater and waste gas without introducing any extra chemicals. The environmental evaluation indicates the carbon-neutral papermaking wastewater reclamation can be achieved through the application of NF-BMED-MC system. This study establishes the promising of NF-BMED-MC as a sustainable alternative to current membrane methods for ZLD of papermaking industry discharges treatment.

Recovery of nickel, phosphorus and nitrogen from electroless nickel-plating wastewater using bipolar membrane electrodialysis

Electroless nickel-plating (ENP) wastewater is challenging to treat because of its complex composition. This study used bipolar membrane electrodialysis (BMED) to remove and recover Ni2+, NH4+, total phosphorus (TP) and NO3− from ENP wastewater. The results show that current density significantly affects ion removal and recovery, current efficiency, specific energy consumption and ion migration velocity. When the current density was 20 mA/cm2, the removal ratios of Ni2+, NH4+, TP and NO3− were 100%, 98.6%, 99.3% and 100% after 14 h, respectively, and their recovery ratios were 92.6%, 75.5%, 94.5% and 90.6%, respectively. The removal kinetics analysis showed that the removal of Ni2+, NH4+, TP and NO3− was consistent with the zero-order kinetics process. The current efficiency variated from 42.5% to 39.0% and 37.7%, and the specific energy consumption decreased from 1.67 to 1.38 and 1.32 kW h/mol with the equipped wastewater compartments increased from one to two and three in a BMED system. Post treatment, Ni2+ was recovered as Ni(OH)2, with a purity of 82.6% (commercial Ni(OH)2 purity = 90%). TP was recovered as struvite with a purity of 95.3%, and the physicochemical properties of the obtained struvite were similar to commercial struvite. NH4+ was recovered as (NH4)2SO4 and NH3•H2O. Therefore, BMED is an effective method to recover Ni2+, TP and NH4+ from ENP wastewater.

Acidic hydrolyzed xylo-oligosaccharides bioactivity on the antioxidant and immune activities of macrophage

Xylo-oligosaccharides (XOS) prepared by the acetic acid hydrolysis of corncob were adulterated with many impurities including pigments, salts, and monosaccharides. Monosaccharides, acids, and most of the pigment were removed by a combination of decolorization, bipolar membrane electrodialysis and catalysis by Gluconobacter oxydans. These steps retain 90% of XOS in the acidolysis slurry. In this study, the effects of purified-XOS (PXOS) and crude XOS (CXOS) on the antioxidant and immune activities of macrophage were compared to verify the bioactivity of acidic hydrolyzed XOS, mainly focusing on the benefits of the purification process. PXOS was more effective in increasing superoxide dismutase activity and reducing malondialdehyde content, and thus had more potent antioxidant activity. In addition, PXOS could more efficiently promote the secretion of tumor necrosis factor-α, interleukin-6, nitric oxide, and interleukin-1β by macrophage. All these data, suggest that the purification process contributed to improve the immunomodulatory activity of XOS from acidolysis slurry.

Asymmetric bipolar membrane electrodialysis for acid and base production

AbstractBipolar membrane electrodialysis (BMED) is a promising technique for upgrading traditional manufacturing procedures and achieving a circular economy. However, the industrial applications of BMED technology have been restricted by the large consumption of expensive bipolar membranes and the unmatching behavior between water splitting and ion migration. Herein, we proposed a novel asymmetric bipolar membrane electrodialysis (ABMED) to regulate the water splitting in the bipolar membrane and orientational ion migration in the electrodialysis (ED). It was found that the ABMED exhibited comparable performances to BMED for acid/base production when the area of the bipolar membrane was reduced to 50% of the monopolar membrane. The total process cost of ABMED was 0.78 $/kg NaOH, which is 21% lower than the BMED process. The asymmetric membrane design was capable to boost the water splitting in the bipolar membrane and to eliminate the concentration polarization in the ED process.

Separation and Concentration of Nitrogen and Phosphorus in a Bipolar Membrane Electrodialysis System.

Struvite crystallization is a successful technique for simultaneously recovering PO43- and NH4+ from wastewater. However, recovering PO43- and NH4+ from low-concentration solutions is challenging. In this study, PO43-, NH4+, and NO3- were separated and concentrated from wastewater using bipolar membrane electrodialysis, PO43- and NH4+ can then be recovered as struvite. The separation and concentration of PO43- and NH4+ are clearly impacted by current density, according to experimental findings. The extent of separation and migration rate increased with increasing current density. The chemical oxygen demand of the feedwater has no discernible impact on the separation and recovery of ions. The migration of PO43-, NH4+, and NO3- fits zero-order migration kinetics. The concentrated concentration of NH4+ and PO43- reached 805 mg/L and 339 mg/L, respectively, which demonstrates that BMED is capable of effectively concentrating and separating PO43- and NH4+. Therefore, BMED can be considered as a pretreatment method for recovering PO43- and NH4+ in the form of struvite from wastewater.

Electrodialysis Desalination with Simultaneous pH Adjustment Using Bilayer and Bipolar Membranes, Modeling and Experiment.

A kinetic model of the bipolar electrodialysis process with a two-chamber unit cell formed by a bilayer (bipolar or asymmetric bipolar) and cation-exchange membrane is proposed. The model allows describing various processes: pH adjustment of strong electrolyte solutions, the conversion of a salt of a weak acid, pH adjustment of a mixture of strong and weak electrolytes. The model considers the non-ideal selectivity of the bilayer membrane, as well as the competitive transfer of cations (hydrogen and sodium ions) through the cation-exchange membrane. Analytical expressions are obtained that describe the kinetic dependences of pH and concentration of ionic components in the desalination (acidification) compartment for various cases. Comparison of experimental data with calculations results show a good qualitative and, in some cases, quantitative agreement between experimental and calculated data. The model can be used to predict the performance of small bipolar membrane electrodialysis modules designed for pH adjustment processes.

Recovery of Acid and Alkaline from Industrial Saline Wastewater by Bipolar Membrane Electrodialysis under High-Chemical Oxygen Demand Concentration

Actual high saline wastewater containing concentrated organics and sodium chloride is a bioenergy and renewable resource. This study compared two different bipolar membrane electrodialysis membranes from two companies' stacks to recover HCl and NaOH from sodium chloride solution and actual chemical wastewater. The results demonstrated that the electrolysis rates were around 1.5 kg/m2h, the HCl and NaOH production rates were about 0.9 kg/m2h, energy consumption was in the range of 1.05-1.27 kWh/kg, and the economic benefits were above 1 yuan/h in BMED systems. From analyzing the performance of seven different BMED membrane stacks, the B2 stack was chosen for electrolyzing actual high salt wastewater to observe the effect of chemical oxygen demand on BMED systems, where electrolytic salt performance, HCl-NaOH alkali production rates, and energy consumption show linear dependence on time for 5000 mg/L chemical oxygen demand wastewater. It illustrated chemical oxygen demand can enhance energy consumption and reduce electrolytic salt performance and the acid and alkali production rates, due to improving the membrane area resistance. In this study, the effect of high COD saline wastewater on the performance of a BMED membrane stack was clarified and the mechanism was analyzed for its practical application in treating chemical high salt wastewater.

Treatment of 2-Mercapto-5-methyl-1,3,4-thiadiazole (MMTD) wastewater by bipolar membrane electrodialysis: MMTD migration, process factors and implications

2-Mercapto-5-methyl-1,3,4-thiadiazole (MMTD), an important intermediate of widely used cefazolin and cefazedone antibiotics, was hardly decyclized during conventional wastewater treatment, raising a great risk to the environment. In this study, a new strategy for treating MMTD wastewater at the source by bipolar membrane electrodialysis (BMED) was proposed, realizing a material closed loop in the processes of MMTD production. Meanwhile, a laboratory-scale BMED system was set up for exploring MMTD migration, process factors, and technology implications. The results revealed that MMTD in the feed compartment may migrate into the acid/base compartment by electromigration and diffusion, the electromigration process of MMTD microspecies was controlled by its ionization, and the diffusion process of MMTD microspecies was influenced by its chemical potential on both sides of the membranes and the types of membranes. The analysis of the BMED process factors showed that these factors such as the initial pH of the feed solution, current density, flow velocity, and initial acid/base concentration affected the acid/base concentration, MMTD leakage, current efficiency, energy consumption, electric field intensity, ion flux, electrical resistance, head loss, and proton leakage. Based on these effects of the BMED process factors, some new strategies were proposed to optimize BMED process. Besides, the implications of BMED technology were affirmed by surveying the feasibility of BMED product recycling. Furthermore, this type of new strategy could be applied to the treatment of other similar wastewater at the source, realizing a closed loop in its production.

Sustainable ammonia recovery from low strength wastewater by the integrated ion exchange and bipolar membrane electrodialysis with membrane contactor system

An energy-efficient and reagent-free system consisting of ion exchange, bipolar membrane electrodialysis and membrane contactor (IE-BMED-MC) was developed for recovering ammonia from low NH4+-N strength wastewater. In this system, NH4+ in the wastewater was firstly removed by ion exchange and then enriched in the acidic regenerant produced by bipolar membrane electrodialysis cell, eventually purified and recovered in membrane contactor without the addition of acid and base. A removal efficiency of over 97 % and recovery efficiency of 9 %-74 % with the energy consumption of 8.12–11.9 kWh·kg−1-N were achieved at current density of 0.5–2.5 mA·cm−2, and the nitrogen flux across the cation exchange membrane (174 g-N·m−2·d-1) was much higher than other ammonia recovery processes with low NH4+-N strength wastewater (<50 g-N·m−2·d-1) owing to the resin enrichment effect. Over six cycles, NH4+-N removal efficiency remained at about 90 % with energy consumption as low as 6 kWh·kg−1-N, where the spent regenerant was utilized as the base stream for next cycle to avoid discharge. Generally, this system realized high-efficiency ammonia recovery from low strength wastewater without chemical input and the cost of $0.425 per kg-N was lower than Haber-Bosch process.

Controllable recovery and recycling of carboxylic acid-polyalcohol deep eutectic solvent for biomass pretreatment with electronically-controlled chemical methodology

Pretreatment of lignocellulosic biomass using deep eutectic solvent (DES) has been demonstrated environmental and valid. Co-existing of donor and acceptor of hydrogen bond makes DES composition more complicated than traditional solvents, which limits their further scale-up utilization. Advances in biomass pretreatment using green solvent DES should excogitate efficient methodology for DES recycling. Electronically-controlled chemical methodology was first put forward to resolve recovery and recycling issue of DES lactic acid-ethylene glycol after biomass pretreatment. The methodology worked based on selectively migrating of lactate Lac- and reserving of ethylene glycol using BP-A-BP bipolar membrane electrodialysis (BMED). Impact of primary factors on DES recovery was carefully studied. Lowest energy consumption for specific DES recovery reached 10.4 kw·h/kg and highest DES recovery rate approached 97.6 %. Cognition acquired from this research indicated a promising and efficient strategy for carboxylic acid-polyalcohol DES recovery with novel electronically-controlled chemical methodology.

Recovery of nickel in the form of Ni(OH)2 from plating wastewater containing Ni-EDTA using bipolar membrane electrodialysis

Ni is often present in plating wastewater as a complexing state. It is difficult to remove this Ni using traditional chemical precipitation technology. In this study, a bipolar membrane electrodialysis system was used to recover Ni in the form of Ni(OH)2 from plating wastewater containing Ni–ethylenediaminetetraacetic acid (Ni-EDTA) without adding chemical reagents. The stable structure of Ni-EDTA can be destroyed by H+ produced by the bipolar membrane to obtain free Ni2+, which can combine with OH− produced by the bipolar membrane to form Ni(OH)2. When the electrolyte Na2SO4 concentration, current density and initial Ni-EDTA concentration were 0.2 mol/L, 16 mA/cm2 and 1000 mg/L, respectively, 99.0% of Ni-EDTA was removed after 32 h. When the system was used to treat actual plating wastewater, 92.1% of Ni-EDTA was removed and 88.7% was recovered. When the number of wastewater compartments in the system was increased from one to three, the current efficiency increased from 1.7% to 5.8%, and the specific energy consumption decreased from 0.39 to 0.19 kW h/g. The results of an X-ray diffraction study indicate that the Ni(OH)2 obtained in this study is similar to commercial Ni(OH)2. Moreover, the recovery mechanism of Ni-EDTA was analysed. Thus, bipolar membrane electrodialysis can be regarded as an effective method to recover Ni from wastewater containing Ni-EDTA.

Impact of Phenol on Membranes during Bipolar Membrane Electrodialysis for High Salinity Pesticide Wastewater Treatment

To achieve a cleaner production, pesticide wastewater with concentrated NaCl can be treated by using a bipolar membrane electrodialysis (BMED) and converted to NaOH and HCl, which minimizes acid and alkali consumption in a pesticide production process. However, ion-exchange membranes (IEMs) are vulnerable to fouling by phenolic substances present in the concentrated NaCl solutions. This work aimed to understand the performance and fouling mechanism of BMED from phenol during the desalination of NaCl and explore an effective cleaning method. The results firstly showed that for the NaCl solutions with higher phenol concentrations, the selectivity of the IEMs was reduced after processing six successive batches of BMED, which led to reverse migration of ions, organics leakage, and an obvious increase in the energy consumption and the concentration of generated acid and alkali. Secondly, IEMs characterization analysis detected that the structure of the IEMs was deformed, while phenol fouling deposits were observed on the surface and interior of the IEMs, especially for the anion exchange membranes (AEMs). Then, the results of soaking tests proved that the phenol could bring about swelling-like degradation to the AEMs and 0.1 wt.% NaOH solution was studied to be the optimized cleaning agent since the performance of the fouled IEMs in the short-running process could be recovered after 5 h of in situ cleaning that removed the phenol fouling deposits efficiently. Finally, the results of a long-running BMED operation treating NaCl solution containing 10 g/L phenol concentration showed that the IEMs were severely fouled, and the fouling was firstly due to the swelling-like mechanism during the initial 12 successive batches, and then should belong to the blockage-like mechanism during the following 20 successive batches. The seriously fouled IEMs could no longer be recovered even after a deep in situ cleaning. This research proves that under appropriate pretreatment or operating conditions, the BMED process is an alternative way of treating wastewater with high salinity and the presence of phenol molecules.

Application of Bipolar Membrane Electrodialysis in Environmental Protection and Resource Recovery: A Review.

Bipolar membrane electrodialysis (BMED) is a new membrane separation technology composed of electrodialysis (ED) through a bipolar membrane (BPM). Under the action of an electric field, H2O can be dissociated to H+ and OH−, and the anions and cations in the solution can be recovered as acids and bases, respectively, without adding chemical reagents, which reduces the application cost and carbon footprint, and leads to simple operation and high efficiency. Its application is becoming more widespread and promising, and it has become a research hotspot. This review mainly introduces the application of BMED to recovering salts in the form of acids and bases, CO2 capture, ammonia nitrogen recovery, and ion removal and recovery from wastewater. Finally, BMED is summarized, and future prospects are discussed.

High-efficiency recovery and regeneration of choline-polyol deep eutectic solvent for biorefinery via bipolar membrane electrodialysis and ultrafiltration

Deep eutectic solvents (DES) have been widely studied for interesting solvent properties in resources utilization and green conversion of energy. Complex composition of DES and lack of recovery techniques restricts their further scale-up application. Exploring efficient recovery and regeneration methodology of DES in biorefinery could be beneficial for low-carbon circular bioeconomy. Recovery and regeneration of choline-polyol DES (choline chloride-ethylene glycol, ChCl-EG) after biomass pretreatment was studied using bipolar membrane electrodialysis (BMED) with ultrafiltration (UF). UF-BMED treatment worked based on the interception of macromolecular degradation products in pretreatment liquor and regional recovery of Ch+, Cl− with EG. Influence of major parameters on DES recovery performance was studied with emphasis. Maximum recovery ratio of DES reached 97.4% and minimum specific energy consumption of DES recovery approached 6.0 kW·h/kg. Cognition gained from this research revealed an efficient technique for DES recycling after biorefinery.

Modeling, Optimization, and Techno-Economic Analysis of Bipolar Membrane Electrodialysis for Direct Air Capture Processes

Bipolar membrane electrodialysis (BPMED) could allow for the complete electrification of direct air capture (DAC) technologies. In this work, we have modeled and optimized two DAC processes based on different electrodialysis cell designs. The technical assessment has been complemented by a detailed economic analysis, showing the advantages but also the current shortcomings of this technology and pathways for advancement. A minimum energy demand of 24 MJ kgCO2–1 has been estimated for the base-case scenario, a result comparable to what has been reported for other liquid-scrubbing DAC technologies. Several solutions to further abate power consumption have been reviewed, with the most promising case providing a 29% reduction. Membrane cost and performance are currently the main limiting factors. In a scenario where cheaper membranes with better performance are assumed to be available, total costs below $250 tonCO2–1 may be feasible, making BPMED a viable fully electrified alternative to other technologies requiring natural gas.