Recovery Of Acid Research Articles

Energy and nutrient recovery from municipal and industrial waste and wastewater - a perspective.

This publication highlights the latest advancements in the field of energy and nutrient recovery from organics rich municipal and industrial waste and wastewater. Energy and carbon rich waste streams are multifaceted, including municipal solid waste, industrial waste, agricultural by-products and residues, beached or residual seaweed biomass from post-harvest processing, and food waste and are valuable resources to overcome current limitations with sustainable feedstock supply chains for biorefining approaches. The emphasis will be on the most recent scientific progress in the area, including the development of new and innovative technologies, such as microbial processes and the role of biofilms for the degradation of organic pollutants in wastewater, as well as the production of biofuels and value-added products from organic waste and wastewater streams. The carboxylate platform, which employs microbiomes to produce mixed carboxylic acids through methane-arrested anaerobic digestion, is the focus as a new conversion technology. Nutrient recycling from conventional waste streams such as wastewater and digestate, and the energetic valorization of such streams will also be discussed. The selected technologies significantly contribute to advanced waste and wastewater treatment and support the recovery and utilization of carboxylic acids as the basis to produce many useful and valuable products, including food and feed preservatives, human and animal health supplements, solvents, plasticizers, lubricants, and even biofuels such as sustainable aviation fuel.

Engineering the by-products pathway in Aureobasidium pullulans for highly purified polymalic acid fermentation with concurrent recovery of l-malic acid

The fermentation of polymalic acid (PMA) by Aureobasidium pullulans, followed by acid hydrolysis to release the monomer l-malic acid (l-MA), has emerged as a promising process for the bio-based production of l-MA. However, the presence of specific by-products significantly affects the quality of the final products. In this study, chassis strains harboring an overexpressed endogenous malate dehydrogenase gene (ApMDH2) were engineered to delete key genes involved in the pullulan, melanin, and liamocin biosynthetic pathways. Furthermore, to enhance PMA synthesis productivity and prevent intracellular NADPH accumulation, an irreversible trans-hydrogenase transformation system was designed to efficiently convert NADPH to NADH. In fed-batch fermentation, the engineered strain produced the highest PMA titer (194.3 ± 1.1 g/L) and l-MA yield (0.89 ± 0.01 g/g) with an increased productivity (1.45 ± 0.06 g/L∙h). Moreover, a total of 86.19 % l-MA, with a purity of 99.7 %, was successfully extracted from fermentation broth.

Flow-electrode capacitive separation of organic acid products and recovery of alkali cations after acidic CO2 electrolysis

Acidic CO2 electrolysis, enhanced by the introduction of alkali cations, presents a strategic approach for improving carbon efficiency compared to processes conducted in neutral and alkaline environments. However, a significant challenge arises from the dissolution of both organic acids and alkali cations in a strongly acidic feed stream, resulting in a considerable energy penalty for downstream separation. In this study, we investigate the feasibility of using flow-electrode capacitive deionization (FCDI) technology to separate organic acids and recover alkali cations from a strongly acidic feed stream (pH ~ 1). We show that organic acids, such as formic acid and acetic acid, are retained in molecular form in the separation chamber, achieving a rejection rate of over 90% under all conditions. Alkali cations, such as K+ and Cs+, migrate to the cathode chamber in ionic form, with their removal and recovery significantly influenced by their concentration and the pH of the feed stream, but responding differently to the types and concentrations of organic acids. The energy consumption for the removal and recovery of K+ is 4 to 8 times higher than for Cs+, and the charge efficiency is significantly influenced by the types of organic acid products and alkali cations. We conduct a series of electrochemical measurements and analyze the impedance spectroscopy, identifying that hindered mass transfer governed the electrode process. Our findings underscore the potential of FCDI as an advanced downstream separation technology for acidic electrocatalysis processes.

A-317 Development of a patient-focused volumetric absorptive microsampling strategy to assess urinary amino acid excretion

Abstract Background Biochemical determinations of urinary amino acid excretion patterns can diagnose specific inborn errors of metabolism (IEM). Clinical management of these genetic metabolic patients may require frequent urine amino acid tests. A simplified process for transporting home collected urine specimens would benefit the IEM community. Volumetric absorptive microsampling (VAMS) is an emergent alternative sampling technique for the collection of dried biological specimens. We describe the development and preliminary validation results of a VAMS strategy for the analysis of creatinine and amino acids (N=22) from microsampled dried urine. Methods Urine creatinine and amino acids were respectively measured in a clinical laboratory setting using established assays on a CobasPro (Roche) and a MassTrak ultra-performance liquid chromatography (UPLC) amino acid analysis (AAA) solution (Waters). Two 30 µL VAMS tips from a Mitra device (Neoteryx) were used to sample each random urine specimen. An ultrasonication-based solvent extraction procedure was optimized to extract the amino acids and creatinine from the VAMS tips. Solvent extracts were subsequently dried by centrifugal evaporation. Extract from one tip was re-dissolved in water and tested for creatinine using an enzymatic method. The other extract was re-dissolved in 0.02 N sodium hydroxide and tested according to the MassTrak AAA procedure, which deploys pre-column AccQTag derivatization with reversed-phase UPLC on a C18 column (2.1 × 150 mm; 1.7 µm) and UV detection at 260 nm. Accuracy, within-batch precision and short-term stability of the optimized VAMS protocol were determined. Results Extraction solvent with a 60:40 (v/v) water:methanol mixture provided the highest average amino acid recovery. This extraction solvent produced higher average amino acid recoveries at pH 11 (89±13%), than pH 3 (82±10%) or pH 7 (72±11%). Creatinine measured from the VAMS tips (N=44) had a consistent negative bias of 20% relative to neat urine (R=0.9905, slope=0.802, intercept=0.02). The creatinine corrected urine amino acid results from the Mitra device were corrected for this observed concentration bias. The accuracy of the amino acid results derived from the VAMS tip vs neat urine was 104 ± 14%. The average within-batch precision (CV%) of the amino acids was 9.8% (range=6.7% (cystine) to 17.6% (arginine)) and 6.2% for creatinine. The average 1 week storage stability at ambient temperature was 91% (range=73% (ornithine) to 107% (glycine)) for the amino acids and 107% for creatinine. The devised VAMS strategy was applied to the analysis of microsampled dried urine from a patient with cystinuria (OMIM no. 220100). Marked elevations in arginine, cystine, lysine and ornithine were respectively observed and are consistent with the biochemical diagnosis of the patient. Conclusions Creatinine corrected amino acid results from the devised VAMS strategy exhibit good precision and accuracy when compared to tradition analyses of neat urine. The potential use of microsampled dried urine for the diagnosis and monitoring of selected IEM has been demonstrated. The analytical and clinical performance of this VAMS protocol must be further validated, including the use of microsampled dried urine from home specimen collections.

Recovery and fractionation of volatile fatty acids from fermented solutions by electrodialysis: electrochemical characterization of anion-exchange membranes

Electrodialysis can be used to recover charged precursors, such as volatile fatty acids (VFAs), of the biopolymers polyhydroxyalkanoates (PHAs). In general, all VFAs are recovered in a receiver solution, despite their advantageous partial fractionation. Herein, the separation of acetic, propionic, butyric, and valeric acids by electrodialysis was evaluated using three anion-exchange membranes (namely, Ralex AMH-PES, Fumasep FAS-PET-130 and PC200D) applying cell voltages from 0V to 2.88V. The mass transfer mechanisms were evaluated by linear sweep voltammetry and chronopotentiometry. Fumasep showed a slightly greater VFAs fractionation capacity than Ralex, while it was much greater for PC200D due to the presence of tertiary amines in its fixed functional groups. Overall, increasing the operating voltage and/or time reduced the degree of VFAs fractionation with all membranes. The higher percent extraction values and greater VFAs fractionation degrees obtained with the PC200D membrane could enhance PHAs storage efficiency.

Benzoic Acid Serves as Precursor of Catalytic HAT Reagent in a Two-Molecule Photoredox System.

The photoinduced regioselective HAT reactions of acetals, ethers, and alcohols using benzoic acids in a two-molecule photoredox system led to the formation of new C-C bonds with alkenes under mild conditions. Aryl carboxy radicals generated from benzoic acids in a two-molecule photoredox system can function as catalytic HAT reagents, even though an excess amount of a hydrogen donor substrate is required. Various acetals, ethers, alcohols, and alkenes can be employed in the photoreaction to provide both high yields of adducts and high recoveries of benzoic acids.

A deep treatment process for chemical polishing wastewater towards resource recovery: Optimization and performance

The chemical polishing industry generates abundant wastewater that contains high concentrations of phosphoric acid and metal ions. In light of the rapid growth of the economy and the stringent demands for sustainability, developing cost-effective and energy-efficient technologies for wastewater treatment is crucial. Herein, an EPRC-ICT-ANT process integrating electrodialysis, iron contact, and alkali neutralization, was proposed to deeply treat chemical polishing wastewater and achieve optimal recovery of acid, phosphorus, and aluminum. The results indicated that with the electrochemical phosphoric acid recovery cell (EPRC), the maximum recovery efficiency and final phosphoric acid concentration were 34.6 % and 25.2 g/L. Following the iron contact tank and alkali neutralization tank (ICT-ANT) treatment, a remarkable 99.17 % removal of Al3+ and 49.5 kg/t wastewater yield of AlPO4 were achieved. Simultaneously, the released Fe2+ and remaining PO43- triggered the rapid formation of vivianite with a yield of 120.7 kg/t wastewater. This comprehensive treatment strategy led to the near-complete removal of Al3+ and PO43- (∼100 %) with an impressive recovery of Al3+ (∼100 %) and PO43- (75.7 %), emphasizing its immense potential for chemical polishing wastewater treatment.

Understanding the Flexibility Challenges of a Plant for Microbial CO2 Electroreduction with Hexanoic Acid Recovery

Understanding the Flexibility Challenges of a Plant for Microbial CO₂ Electroreduction with Hexanoic Acid Recovery

Efficient Generation of Protein Pockets with PocketGen.

Designing small-molecule-binding proteins, such as enzymes and biosensors, is crucial in protein biology and bioengineering. Generating high-fidelity protein pockets areas where proteins interact with ligand molecules, is challenging due to complex interactions between ligand molecules and proteins, flexibility of ligand molecules and amino acid side chains, and complex sequence-structure dependencies. Here, we introduce PocketGen, a deep generative method for generating the residue sequence and the full-atom structure within the protein pocket region that leverages sequence structure consistency. PocketGen consists of a bilevel graph transformer for structural encoding and a sequence refinement module that uses a protein language model (pLM) for sequence prediction. The bilevel graph transformer captures interactions at multiple granularities (atom-level and residue/ligand-level) and aspects (intra-protein and protein-ligand) with bilevel attention mechanisms. For sequence refinement, a structural adapter using cross-attention is integrated into a pLM to ensure structure-sequence consistency. During training, only the adapter is fine-tuned, while the other layers of the pLM remain unchanged. Experiments show that PocketGen can efficiently generate protein pockets with higher binding affinity and validity than state-of-the-art methods. PocketGen is ten times faster than physics-based methods and achieves a 95% success rate (percentage of generated pockets with higher binding affinity than reference pockets) with over 64% amino acid recovery rate.

Mechanism underlying anion-sieving in poly(ionic liquid)-based membrane: Effective acid recovery from engineering waste

Anion exchange membranes (AEMs) are promising for recovering acid from different engineering effluent due to their lower energy consumption, positive environmental impact, and potential for providing clean water resources. Utilizing the diffusion dialysis (DD) process, AEMs effectively retain metal ions while selectively allowing fast proton permeation. Achieving high hydrophilicity, proton conductivity, and ion exchange capacity through exact control of polymeric structure and chemical composition is crucial for enhancing the efficiency of the acid recovery process. This study presents the findings on the impact of novel Poly(ionic liquid) on cellulose acetate-based AEMs for acid recovery through DD application. In this study, interconnected nanochannel AEMs with high acid permeability are engineered using a straightforward blending technique. Poly(3-butyl-1-vinylimidazolium bromide-co-methyl methacrylate-co-styrene) (poly([BVIM]-[Br]–co–MMA-co-Styrene, PIL) is blended with cellulose acetate to achieve ionic crosslinking, resulting in a mechanically stable membrane. The dosage of PIL within the membrane matrix plays a vital role in determining the prepared membranes' physicochemical properties and ion exchange capabilities, which exhibit excellent thermal stability. Remarkably, the optimal AEM (7.5 % PILM) exhibits a high acid dialysis coefficient (UH+) of 1.05 m/h and a separation factor (S) of 802, outperforming previously reported state-of-the-art AEMs and commercial membranes. These findings indicate that the prepared AEMs are highly effective for acid recovery through DD. Notably, our work stands out by introducing new AEMs with superior acid dialysis performance and selectivity.

Optimization of PET depolymerization for enhanced terephthalic acid recovery from commercial PET and post consumer PET-bottles via low-temperature alkaline hydrolysis

The increasing demand for plastic has resulted in a surge in plastic waste production. Polyethylene terephthalate (PET), commonly used in beverage bottle manufacturing, is only partially recycled, with an estimated recycling rate of just 28.4% in 2019. This accumulation of plastic waste is harmful to the environment and living organisms, necessitating effective recycling methods for PET waste. One promising method is alkaline hydrolysis using NaOH, which can break down PET into its monomer components, terephthalic acid (TPA) and ethylene glycol (EG). This process not only recycles PET efficiently but also manages contaminants effectively, producing high-quality TPA, supporting the development of a circular economy. This study looks into PET depolymerization via alkaline hydrolysis at low temperature by investigating effects of various factors: pH levels, water to ethanol ratio, NaOH concentration, NaOH to PET ratio, reaction time, PET size, reusability of unreacted PET, air plasma pretreatment of PET, and different kinds of PET. Promisingly, PET conversion rates of over 90% and a TPA purity of 99.6% were achieved in this study highlighting the efficacy of alkaline hydrolysis in depolymerizing post-consumer PET waste. Ultimately, this research advances sustainable plastic waste management and supports the integration of PET into a circular economy framework.

Facile recovery of terephthalic acid from PET bottles via acid hydrolysis with nitric acid and applications in synthesis of cobalt MOFs

Facile recovery of terephthalic acid from PET bottles via acid hydrolysis with nitric acid and applications in synthesis of cobalt MOFs

Charge mediated nano-filtration for recovering sinapic acid from a mustard bran hydrolysate

The recovery of valuable chemicals, such as sinapic acid, from enzymatic hydrolysates is essential to enabling a sustainable biorefinery. In this study, we designed a system to recover sinapic acid produced chemo-enzymatically from waste mustard bran. The process involves sequential separation, beginning with size partitioning using ultrafiltration for enzyme removal and recovery, followed by charge-mediated size partitioning via nanofiltration to isolate sinapic acid from other extracts. Four polyethersulfone (PES) ultrafiltration membranes with molecular weight cut-offs (MWCOs) of 5000 and 10 000 Da and maximum allowable working pressures (MAWPs) of 3 and 10 bar were screened for their effectiveness in removing Bovine Serum Albumin (BSA) as a model compound. Subsequently, these membranes were applied to recover the feruloyl esterase enzyme. The membrane with an MWCO of 5000 Da and an MAWP of 10 bar achieved 97.93 % enzyme recovery with a permeate flow rate of 31.4 L/h/m2 at 6 bar. Next, we evaluated the effects of zeta potential interactions on the preferential rejection of sinapic acid using various nanofiltration membranes with potentially charged surfaces, including polyimide, silicon-based thin film composite, and polypiperazine amide membranes with MWCOs ranging from 150 to 600 Da. The polypiperazine amide membrane demonstrated the highest recovery of sinapic acid, achieving 86 % recovery from a model solution and 64 % recovery from mustard bran hydrolysate. Compositional analysis of the permeate confirmed that the rejection rate (R) is influenced primarily by the pKa rather than molecular size, following the trend: sinapic acid (pKa = 4.58; 224.2 Da; R = 64.0 %), acetic acid (pKa = 4.76; 60.1 Da; R = 23.8 %), xylose (pKa = 12.15; 150.1 Da; R = 13.7 %), glucose (pKa = 12.28; 180.2 Da; R = 8.7 %), and arabinose (pKa = 12.34; 150.1 Da; R = 8.5 %). The zeta potential interactions across nanofiltration membranes enhanced sinapic acid recovery from the mustard bran hydrolysate, hence, charge mediation significantly influenced the membrane separation of these complex mixtures with varying pKa values.

Purification and Kinetics of Chlorogenic Acid from Eucommia ulmoides Oliver Leaves by Macroporous Resins Combined with First-Principles Calculation

Background: A simple and effective method to separate chlorogenic acid from Eucommia ulmoides leaves with macroporous resin was studied in this paper. Methods: In order to optimize the separation process of chlorogenic acid from Eucommia ulmoides leaves, dynamic adsorption and desorption experiments were carried out on a glass column filled with XDA-8 resin. Based on the First-principles calculation, the possible adsorption models were simulated. Results: Among the six macroporous resins, XDA-8 showed good adsorption/desorption capacity and a high adsorption/desorption ratio for chlorogenic acid. After being treated with XDA-8 resin once, the content of chlorogenic acid from the extraction increased by 525%, and the recovery of chlorogenic acid reached 85.36%. Conclusion: At 25°C, the adsorption behavior of chlorogenic acid on XDA-8 resin was consistent with the Langmuir isotherm model and pseudo-second-order kinetic model. Furthermore, by calculating the charge changes of the O atom at each position in the chlorogenic acid molecule and the H atom at the adsorption site in polystyrene molecule with resin skeleton, and combining with the electron cloud density distribution diagram of chlorogenic acid and resin skeleton, the adsorption of chlorogenic acid by XDA-8 resin is mainly due to the charge transfer, which causes the electron cloud to overlap.

Recovery of carboxylic acids from actual effluent by using sequential cationic-anionic adsorption steps at semi pilot scale

This work presents for the first time an exhaustive experimental assessment at semi-pilot scale for the sequential use of cationic-anionic adsorption columns for recovering carboxylic acids (CAs) from a real fermentation broth. The consecutive steps were dedicated to i) remove cations limiting the CAs interaction with the functional group of the anionic resin, and ii) adsorb CAs onto the anionic resin, respectively. The experimental broth was obtained from anaerobic co-fermentation of urban biowaste (UBW-broth). Breakthrough (BT) tests were firstly performed with the cationic column containing the strong-acid resin Lewatit® S2568H. This allowed both to assess the single process and to prepare 60 L of decationised UBW-broth to be used in the BT-tests with the anionic column (containing the weak-basic resin Lewatit® A365). Both columns were assessed (at 25°C) under packed and expanded bed modes, by feeding at different rates the actual UBW-broth or synthetic solutions. Main study innovative outputs were: 1) 100 % of the CAs occurring in UBW-broth were recovered with the proposed system; 2) best performances were obtained under expanded bed mode of operation, allowing to use 100 % of the installed capacity; 3) the affinity of other organic matter else than CAs resulted weaker than Na+/NH4+ and CAs/PO4x-/Cl- in both cationic and anionic columns, respectively (i.e. low adsorption performances generally reported are due to inorganic cations/anions presence); 4) a very preliminary economic analysis carried out on the basis of the obtained data indicates overall costs ranging 0.58–1.49 EUR/kg of CAs (depending on the process configuration).

Leveraging an innovative process integration using highly acid-immune blend membranes for enhanced acid recovery and selective salt separation

We investigate the efficiency and advantage of the integrated diffusion dialysis-electrodialysis (DD-ED) system over the DD process for acid recovery with highly acidic wastewater. The investigation uses various acid (HCl/H2SO4) /salt mixtures encompassing iron, copper and aluminium salts (FeCl2, CuCl2, AlCl3, and FeSO4) as simulated feed. The membrane is prepared using blend mixture of polyvinylidene fluoride (PVDF) and polymethyl methacrylate-co-poly chloromethyl styrene copolymer (PMMA-co-PCMSt) solution by non-solvent induced phase inversion on a nonwoven fabric followed by treatment with different tertiary amines. Representative AEM-Q3 membrane prepared by the post modification of blend membrane with a mixture of N, N, N’, N’- tetramethyl diamino hexane (TMDAH) and trimethyl amine (TMA) (1: 1 w/w %) exhibited the best-balanced performance. The membrane recovered a 84.2% AR (%) of acid with 96.28% purity (%) at a flux (JH+) of 7.08 × 10-4 mol cm-2 h-1 from 3 M HCl and 0.2M FeCl2 mixture making it suitable for further studies. A comprehensive comparative study drawn between the DD and integrated DD-ED showed that there was a 2.3 fold increment in acid recovery for the integrated process over the DD process (for the HCl-FeCl2 system). The membranes have also shown good monovalent (Cl-) and bivalent (SO42-) anion selectivity of 7.8. However, the selectivity was further improved to 12.28 by modification of AEM-Q3 membrane, which is double side cast (referred as AEM-Q3/b). The synthetic strategy of the membrane is easy and scalable and has potential for both acid recovery and selective salt separation by ED process.

Longitudinal associations of plasma amino acid levels with recovery from malarial coma

BackgroundDisordered amino acid metabolism is observed in cerebral malaria (CM). This study sought to determine whether abnormal amino acid concentrations were associated with level of consciousness in children recovering from coma. Twenty-one amino acids and coma scores were quantified longitudinally and the data were analysed for associations.MethodsIn a prospective observational study, 42 children with CM were enrolled. Amino acid levels were measured at entry and at frequent intervals thereafter and consciousness was assessed by Blantyre Coma Scores (BCS). Thirty-six healthy children served as controls for in-country normal amino acid ranges. Logistic regression was employed using a generalized linear mixed-effects model to assess associations between out-of-range amino acid levels and BCS.ResultsAt entry 16/21 amino acid levels were out-of-range. Longitudinal analysis revealed 10/21 out-of-range amino acids were significantly associated with BCS. Elevated phenylalanine levels showed the highest association with low BCS. This finding held when out-of-normal-range data were analysed at each sampling time.ConclusionLongitudinal data is provided for associations between abnormal amino acid levels and recovery from CM. Of 10 amino acids significantly associated with BCS, elevated phenylalanine may be a surrogate for impaired clearance of ether lipid mediators of inflammation and may contribute to CM pathogenesis.

(Invited) Engendering Non-Noble Metal Catalysts for Electrolyzers: From Fundamentals to Devices

In memory of Prof. Sri Narayanan, this presentation will showcase the electrocatalysis of hydrogen evolution reaction (HER) and oxygen reduction in the context of oxygen depolarization cathode (ODC) for electrolyzer applications. Fundamentals of HER/HOR in alkaline pH will be presented in the context of various theories proposed to rationalize pH, cations, and structure effects. It will be shown that none of them can effectively explain all observations. In this presentation, four schools of thought for HER/HOR will be discussed, focusing on the strengths and shortcomings of each hypothesis and highlighting the magnitude of electrochemical interface structure in hydrogen electrocatalysis. Translation of these fundamental concepts into a durable electrocatalyst will be presented as a functionalized mono-metallic Ni catalyst concept. Durability results will be presented from both steady-state operation and uncontrolled shutdown conditions. These will be presented in conjunction with anion exchange membranes such as VersogenÒ, OrionÒ. Another cathodic process in the context of electrolysis is the oxygen-depolarized cathode, typically paired with anodic processes, such as chlorine generation. ODC cathode using coordinated Fe-N-C catalysts will be presented in the context of hydrochloric acid recovery, where activity and durability in the context of both fundamentals of oxygen reduction reaction mechanism and effects of uncontrolled shutdown will be presented.

Semi-Interpenetrating Polymer Network Anion Exchange Membranes Based on Quaternized Polybenzoxazine and Poly(Vinyl Alcohol-Co-Ethylene) for Acid Recovery by Diffusion Dialysis.

Acid recovery from acidic waste is a pressing issue in current times. Chemical methods for recovery are not economically feasible and require significant energy input to save the environment. This study reported a semi-interpenetrating polymer network (semi-IPN) anion exchange membranes (AEMs) for acid recovery by diffusion dialysis with excellent dimensional stability, high oxidation stability, good acid dialysis coefficient (UH +) and high separation factor (S). Semi-IPN AEMs are prepared by ring-open cross-linked quaternized polybenzoxazine (AQBZ) with poly(vinyl alcohol-co-ethylene), where AQBZ is obtained by Mannich reaction and Menshutkin reaction. All four proportions of semi-IPNs exhibit clear micro-phase separation, which is conducive to ion transport. The water uptake (WU) of the four semi-IPNs ranges from 14.2 % to 19.2 %, while the swelling ratio (SR) remains between 8.7 % and 11.3 %. These results indicate that the cross-linked structure in the designed semi-IPNs effectively control swelling and ensure dimensional stability. The thermal degradation temperature (Td5) of semi-IPN4:6 to semi-IPN7:3 varies from 309 °C to 289 °C, with an oxidation stability weight loss rate (WOX) ranging from 91.5 % to 93.5 %, demonstrating excellent thermal stability and oxidation stability. The semi-IPNs also show good UH + values ranging from 11.9-16.3*10-3 m/h and high S values between 38.6 and 45.9, indicating the promising potential of the semi-IPNs.

Recovery of both volatile fatty acids and ammonium from simulated wastewater: Performance of membrane contactor and understanding the effects of osmotic distillation

Membrane Contractor (MC) is a separation method that has had growing interest because of its recovery performance and comparably lower energy consumption. Herein, a two-stage recovery MC system was investigated to recover volatile fatty acids (VFAs) and ammonium from simulated wastewater. The MC achieved the total VFA recovery of 77 % ± 3 %, 82 % ± 5 %, and 74 % ± 8 %, with 0.1, 0.3, and 0.5 M NaOH permeate solutions, respectively. The 0 M NaOH permeate recovered only 38 % ± 2 % of the VFAs due to the osmotic distillation occurring in the opposite direction (permeate to feed) of the VFA transport. Despite the initial pH of the feed solution, osmotic distillation was similar when the permeate was maintained at 0.5 M NaOH. The vapor pressure changes at each sampling period showed high correlation with the water transported (R2=0.958). Ammonium recovery was not significantly different when the pH was maintained while increasing the molarity of the H2SO4 permeate, likely due to the high vapor pressure of ammonia gas. Multi-criteria decision analysis was used to determine the optimal operation conditions for MC operation. The results of this study would encourage further exploration of MC technologies for efficiency recovery of VFA and ammonium from wastewater.