Membranes in wastewater treatment: Integrated crystallization is essential

Saline wastewater, often containing inorganic as well as organic material, is produced in various contexts and is very difficult to treat, particularly with the additional challenge of a low/high pH and the presence of heavy metals. In this context the developed world (industrial) meets the developing world (mining) and growth countries like China (mining and industry). The aim of this presentation is to propose a feasible integrated system to reclaim water from saline wastewater or wastewater containing metals for water reuse, to regenerate acid/base from wastewater and to recover metals or salts as precipitates. At first, the feasibility of a hybrid system consisting of a fluidized pellet reactor and an electrodialysis (ED) unit will be discussed to treat simulated and real wastewaters, mainly in view of recovery of the phosphate fraction. A fluidized pellet reactor can be used to remove the scaling potential before ED treatment; or directly to precipitate phosphates or heavy metals. This requires a profound knowledge of the water chemistry in terms of supersaturation of minerals, which can be studied using geochemical equilibrium software. The potential for such hybrid systems will be outlined

Impact of Formulation of Photocurable Precursor Mixtures on the Performance and Dimensional Stability of Hierarchical Cation Exchange Membranes

This work presents a systematic approach to formulating UV curable ionomer coatings that can be used as ion-exchange membranes when they are applied on porous substrates. Ion-exchange membranes fabricated in this way can be a cost-effective alternative to perfluorosulfonic acid membranes, such as Nafion and similar thin ionomer film membranes. Hierarchically structured coated membranes find applications for energy storage and conversion (organic redox flow batteries and artificial photosynthesis cells) and separation processes (electrodialysis). Designing the ionomer precursor for membrane formulation requires the introduction of compounds with drastically different properties into a liquid mixture. Hansen solubility theory was used to find the solvents to compatibilize main formulation components: acrylic sulfone salt (3-sulfopropyl methacrylate potassium salt) and hexafunctional polyester acrylate cross-linker (Ebecryl 830), otherwise nonmiscible or mutely soluble. Among the identified suitable solvents, acrylic acid and acetic acid allowed for optimal mixing of the components and reaching the highest levels of sulfonic group content, providing the desired ion-exchange capacity. Interestingly, they represented a case of a reactive and nonreactive solvent since acrylic acid was built into the ionomer during the UV curing step. Properties of the two membrane variants were compared. Samples fabricated with acetic acid exhibit improved handleability compared with the case of acrylic acid. Acetic acid yielded a lower area-specific resistance (6.4 ± 0.17 Ohm·cm2) compared to acrylic acid (12.1 ± 0.16 Ohm·cm2 in 0.5 M NaCl). This was achieved without severely suppressing the selectivity of the membrane, which was standing at 93.4 and 96.4% for preparation with acetic and acrylic acid, respectively.Research carried out under HYSOLCHEM: This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement no. 101017928

Comparison between hydrophilic and hydrophobic metal nanoparticles on the phase separation phenomena during formation of asymmetric polyethersulphone membranes

Inorganic nanoparticles have been applied as additive in membrane synthesis for improving different properties from the base polymer such as hydrophilicity, fouling resistance or permselectivity. To investigate the changes caused by the presence of the inorganic nanoparticles in the formation of the membrane structure, two different metallic compounds with opposite hydrophilicity were used as additives: hydrophilic zinc oxide (ZnO) and hydrophobic tungsten disulphide (WS2). For this purpose, the effect of these metal nanoparticles at ultra-low concentrations (0.05 and 0.25 wt% metal nanoparticles/polymer ratio) in the preparation of flat-sheet membranes based on polyethersulphone (PES) by immersion-precipitation method was investigated. N-methyl-2-pyrrolidone (NMP) was used as solvent. The influence of both metal nanoparticles on the characteristics and permselective properties of PES membranes was studied with microscopic observations, contact angle measurements, and filtration experiments. Although the incorporation of metal nanoparticles could turn the system into thermodynamically unstable, the demixing process during formation of membranes was slightly delayed, suppressing the macrovoid formation (remarkably using WS2). Regardless the nature of the metal nanoparticles, results showed an overall improvement in membrane hydrophilicity and permselectivity by adding metal nanoparticles compared to the control PES membrane, demonstrating that the behaviour of both metal nanoparticles at ultra-low concentrations was very similar.García Ivars, J.; Iborra Clar, MI.; Alcaina Miranda, MI.; Van Der Bruggen, B. (2015). Comparison between hydrophilic and hydrophobic metal nanoparticles on the phase separation phenomena during formation of asymmetric polyethersulphone membranes. Journal of Membrane Science. 493:709-722. doi:10.1016/j.memsci.2015.07.009S70972249

Current status of textile wastewater management practices and effluent characteristics in Tanzania

This research article published by IWA Publishing, 2021Textile wastewater from wet processing units is a major environmental problem. Most chemicals, including dyes, are only partly consumed, resulting in highly colored wastewater containing a variety of chemicals released into the environment. This paper gives information on the current management of textile wastewater in Tanzania. A semiquantitative analysis was done to identify the main types of chemicals used in wet processing units, wastewater characteristics and existing wastewater treatment methods in the textile industry. The performance evaluation of the existing wastewater treatment plants is also discussed. The advantages of integrating constructed wetlands with the existing treatment facilities for textile wastewater are explained. It has been observed that pretreatment and dying/printing of the fabrics are the main two processes that produce wastewater in many textile companies. Main pollutants are chemicals used from pretreatment and materials removed from de-sizing, bleaching and scouring processes. Dyes, printing pigments and dye auxiliaries are the main pollutants from the dyeing/printing process. Most of the textile companies in Tanzania are equipped with effluent treatment plants. Wastewater treatment plants have basically similar units, which are coagulation-flocculation, sedimentation through clarifiers and aerobic reactor. However, their effluents do not meet discharge limits stipulated by the Tanzania Bureau of Standards (TBS)

Deposition of toxic metal particles on rough nanofiltration membranes

Two nanofiltration (NF90 and Nano-Pro-3012) membranes were investigated for their capacity to remove metal ions. This study presents the effect of membrane roughness on the removal of toxic metal ions during dead end membrane filtration. Atomic force microscopy, scanning electron microscopy, WSXM software and ImageJ were used to characterize the roughness of the membranes. Gradual decrease in filtration permeate flux was observed as foulants accumulated at the interface of the membranes; filtration permeate flux varied from 20 L/m2/h to 14 L/m2/h and 11 L/ m2/h to 6 L/m2/h for NF90 and Nano-Pro-3012, respectively. NF90 membrane was more prone to fouling than the Nano- Pro-3012 membrane: the percentage flux reduction was higher for NF90 (3.6%) than Nano-Pro-3012 (0.98%). The bearing ratio of the fouled NF90 exhibited a high peak of 7.09 nm than the fouled Nano-Pro-3012 with the peak of 6.8 n

TCR Gene Transfer: MAGE-C2/HLA-A2 and MAGE-A3/HLA-DP4 Epitopes as Melanoma-Specific Immune Targets

Adoptive therapy with TCR gene-engineered T cells provides an attractive and feasible treatment option for cancer patients. Further development of TCR gene therapy requires the implementation of T-cell target epitopes that prevent “on-target” reactivity towards healthy tissues and at the same time direct a clinically effective response towards tumor tissues. Candidate epitopes that meet these criteria are MAGE-C2336-344/HLA-A2 (MC2/A2) and MAGE-A3243-258/HLA-DP4 (MA3/DP4). We molecularly characterized TCRαβ genes of an MC2/A2-specific CD8 and MA3/DP4-specific CD4 T-cell clone derived from melanoma patients who responded clinically to MAGE vaccination. We identified MC2/A2 and MA3/DP4-specific TCR-Vα3/Vβ28 and TCR-Vα38/Vβ2 chains and validated these TCRs in vitro upon gene transfer into primary human T cells. The MC2 and MA3 TCR were surface-expressed and mediated CD8 T-cell functions towards melanoma cell lines and CD4 T-cell functions towards dendritic cells, respectively. We intend to start testing these MAGE-specific TCRs in phase I clinical trial

A new process for the recovery of ammonia from ammoniated high-salinity brine

This paper describes a new method for the recovery of high-concentration ammonia from water in the form of ammonium chloride, ammonium hydroxide and ammonium carbonate. The method was applied to the Solvay process, in which sodium bicarbonate is produced through the reaction of ammoniated brine and CO2 gas. The Solvay effluent contains ammonia in the form of soluble ammonium chloride. The proposed method is based on the recovery of ammonia using a high-alkalinity reactant, calcium oxide (CaO), in a closed electrocoagulation cell operating at a specific current density. The recovered ammonia is collected as a gas within a closed cell containing deionized (DI) water at room temperature. Afterwards, the collected solution (DI water-NH3 gas) is concentrated through a separate process, and is then reused in the Solvay process and other applications. The electrocoagulation process is applied to the treatment cell using aluminum electrodes and a current density of 5-15 mA/cm2 . After 7 h of treatment using the electrocoagulation cell, a high reduction of the ammonia concentration-99%-was realized after ~9 h of the electrochemical treatment. The initial ammonia concentration in a Solvay effluent of 13,700 mg/L N was decreased to 190 mg/L N. Furthermore, an ammonia recovery of 77.1% in the form of ammonium hydroxide was achieved. Generally, this process, which starts at room temperature, can result in an energy reduction of 80%-from 7.8 to 2.3 kWh/kg NH3-compared to conventional processes, which entail heating the Solvay effluents to 160?C. The proposed system and method were found to be suitable for the recovery of ammonia from ammoniated water, and can be utilized for the treatment of landfill leachate, and municipal and industrial wastewater.Funding: This research was funded by United Arab Emirates University, grant number G00002622.Scopu

Sorption of pesticide endosulfan by electrodialysis membranes

Endosulfan (ES) is a micropollutant found in reverse osmosis concentrates from water reuse applications. Electrodialysis (ED) can remove and recover charged solutes from such concentrates. While polar compounds cannot normally be removed, their fate in ED is important as they can contribute to membrane fouling/poisoning and be released during cleaning. High adsorption of ES to ED membranes was observed. Consequently, the influence of solution pH and presence of humic acid (HA) on sorption mechanisms of ES to ion-exchange membranes during batch sorption isotherm and ED experiments were investigated systematically. ES-membrane partition coefficients (log KAEM/CEM) quantified through sorption isotherm experiments suggested that ES sorption was resultant of membrane catalysed ES degradation, hydrogen bonding and cation– interactions between ES and membrane functional groups. ES sorption at pH 7 (550 μg/cm3) was greater than sorption at pH 11 (306 μg/cm3) due to alkaline hydrolysed ES and resultant decrease in bonding capacity with the membranes at high pH. The presence of HA reduced sorption at pH 7 (471 μg/cm3) and 11 (307 μg/cm3) due to HA competitive sorption. Partial membrane desorption was noted in isotherm (<20%) desorption experiments and was dependent on the initial mass sorbed, solvent pH and resultant membrane interactions