Batch Tests Research Articles

A new process related impurity identification, characterization, development of analytical method by HPLC and method validation for Voriconazole API

AbstractDuring the testing of laboratory Voriconazole API batches, one unidentified impurity (IMP-5.312) was detected employing the Pharmeuropa HPLC technique at a level in excess of 0.10%. This IMP-5.312 was synthesized and then characterized as 6-(3-(2,4-difluorophenyl)-3-hydroxy-4-(1H-1,2,4-triazol-1-yl) butan-2-yl)-5-fluoropyrimidin-4-ol by the corresponding spectral information (MS, 1H-NMR, 13C-NMR, and IR). The IMP-5.312 impurity was effectively quantified using an enhanced HPLC based-technique that was developed as well as validated. The approach made use of a Novapak C18 column with an inner diameter of 3.9 mm and a length of 150 mm (4.0 µm) for chromatographic separation. The analysis of IMP-5.312 was made at 45 °C, with a flow rate (isocratic) of 1.0 mL min−1 and a 256 nm detection wavelength. Acetonitrile, methanol, and 0.1% aqueous trifluoro acetate buffer (pH 4.0) were mixed at a ratio of 15:30:55 (v/v/v) to create the mobile phase for a 20 μL sample injection. The linearity range of 0.25281–1.51690 μg mL−1 had a correlation coefficient more than 0.99942, and the accuracy ranged from 89.3 to 100.3%. It was noted that the established HPLC based-technique was sensitive, specific, and precise. The technique was executed on the current batches of VRC API for IMP-5.312 analysis, and the outcomes were good. For quality control purposes during the manufacturing procedure of VRC, the identification as well as analysis of IMP-5.312 should be helpful. The in silico approach was applied to predict the IMP-5.312 toxicity. The reports indicated that IMP-5.312 in non-mutagenic and categorized as ICH M7 class-5 impurity.

Projektowanie zakładu uzdatniania wody przy wsparciu modeli laboratoryjnych

The subject of the research focused on the possibilities of supporting the design of surface water treatment plants using laboratory models. Within the pilot study, the possibilities of using different water treatment processes in the treatment of water from the water reservoir Nové Mlýny in the Czech Republic were assessed. The planned treatment plant is to supply a future recreational site from a shallow reservoir with significant eutrophication and chemical industry in the drainage basin. Coagulation, sedimentation, dissolved air flotation, membrane filtration processes and adsorption on granular activated carbon were investigated. These processes were identified by the preliminary study as applicable to water treatment and it was necessary to determine which could be applied given the site conditions. Laboratory models for the individual processes were used during the laboratory testing. During the research, problems encountered were debugged and the models were modified and some extensions were added to the original models. The coagulation and sedimentation processes were investigated using conventional jar tests. The dissolved air flotation process was simulated using a modified jar test and a lab scale model. Different types and doses of coagulants, mixing parameters and residence times were investigated in the tests. Turbidity value was used as an optimization parameter due to its rapidity of determination and low cost. For some tests, potassium permanganate oxidizability (also known as the permanganate index) was also used as an evaluation parameter so that different evaluation parameters could be compared. In addition, for the dissolved air flotation process, the parameters of the produced sludge - its quantity, suspended solids content and chemical oxygen demand - were monitored. These parameters are crucial for discharge of waste water into the sewer and its costs. The adsorption tests on granular activated carbon were performed as batch tests. The evaluation parameter was the manganese index. Another possible variant of activated carbon tests is a continuous flow-through column. These columns also allow monitoring of the process of fouling and the evolution of the effluent over time. The pilot project then used the results of the laboratory tests to create a design for a treatment plant in the area of interest and selected parts of the project documentation. The pilot project demonstrated the usefulness of laboratory testing as a tool to support the design of drinking water treatment plants. At the same time, these tests allow for a faster and more certain identification of the appropriate water treatment technology and thus reduce the extent of semi-operational testing at the site, leading to a more efficient use of funds by investors.

Macrophyte assisted phytoremediation and toxicological profiling of metal(loid)s polluted water is influenced by hydraulic retention time.

The present study reports findings related to the treatment of polluted groundwater using macrophyte-assisted phytoremediation. The potential of three macrophyte species (Phragmites australis, Scirpus holoschoenus, and Typha angustifolia) to tolerate exposure to multi-metal(loid) polluted groundwater was first evaluated in mesocosms for 7- and 14-day batch testing. In the 7-day batch test, the polluted water was completely replacedand renewed after 7days, while for14days exposure, the same polluted water, added in the first week, was maintained. The initial biochemical screeningresults of macrophytes indicated that the selected plants were more tolerant to the provided conditions with 14days of exposure. Based on these findings, the plants were exposed to HRT regimes of 15 and 30days. The results showed that P. australis and S. holoschoenus performed better than T. angustifolia, in terms of metal(loid) accumulation and removal, biomass production, and toxicity reduction. In addition, the translocation and compartmentalization of metal(loid)s were dose-dependent. At the 30-day loading rate (higher HRT), below-ground phytostabilization was greater than phytoaccumulation, whereas at the 15-day loading rate (lower HRT), below- and above-ground phytoaccumulation was the dominant metal(loid) removal mechanism. However, higher levels of toxicity were noted in the water at the 15-day loading rate. Overall, thisstudy provides valuable insights for macrophyte-assisted phytoremediation of polluted (ground)water streams that can help to improve the design and implementation of phytoremediation systems.

Characterization and Performance of Peanut Shells in Caffeine and Triclosan Removal in Batch and Fixed-Bed Column Tests.

Peanut shells' adsorption performance in caffeine and triclosan removal was studied. Peanut shells were analyzed for their chemical composition, morphology, and surface functional groups. Batch adsorption and fixed-bed column experiments were carried out with solutions containing 30 mg/L of caffeine and triclosan. The parameters examined included peanut shell particle size (120-150, 300-600, and 800-2000 µm), adsorbent dose (0.02-60 g/L), contact time (up to 180 min), bed height (4-8 cm), and hydraulic loading rate (2.0 and 4.0 m3/m2-day). After determining the optimal adsorption conditions, kinetics, isotherm, and breakthrough curve models were applied to analyze the experimental data. Peanut shells showed an irregular surface and consisted mainly of polysaccharides (around 70% lignin, cellulose, and hemicellulose), with a specific surface area of 1.7 m2/g and a pore volume of 0.005 cm3/g. The highest removal efficiencies for caffeine (85.6 ± 1.4%) and triclosan (89.3 ± 1.5%) were achieved using the smallest particles and 10.0 and 0.1 g/L doses over 180 and 45 min, respectively. Triclosan showed easier removal compared to caffeine due to its higher lipophilic character. The pseudo-second-order kinetics model provided the best fit with the experimental data, suggesting a chemisorption process between caffeine/triclosan and the adsorbent. Equilibrium data were well-described by the Sips model, with maximum adsorption capacities of 3.3 mg/g and 289.3 mg/g for caffeine and triclosan, respectively. In fixed-bed column adsorption tests, particle size significantly influenced efficiency and hydraulic behavior, with 120-150 µm particles exhibiting the highest adsorption capacity for caffeine (0.72 mg/g) and triclosan (143.44 mg/g), albeit with clogging issues. The experimental data also showed good agreement with the Bohart-Adams, Thomas, and Yoon-Nelson models. Therefore, the findings of this study highlight not only the effective capability of peanut shells to remove caffeine and triclosan but also their versatility as a promising option for water treatment and sanitation applications in different contexts.

Anaerobic Two-Phase Co-Digestion for Renewable Energy Production: Estimating the Effect of Substrate Pretreatment, Hydraulic Retention Time and Participating Microbial Consortia

Green and sustainable economies have recently become a key issue in long-term growth and well-being. Co-digestion of various waste materials in an eco-friendly way through biogas production has become the preferred method for their utilization and valorization. The possibility of hydrogen and methane yield maximization depends on the most suitable alkali reagent for pretreatment of waste lignocellulosic material, which was revealed in batch tests to determine the hydrogen production potential. The mixture for digestion consisted of pretreated wheat straw mixed with waste algal biomass in a ratio of 80:20 (w/w). The maximum hydrogen yield was achieved after applying sodium hydroxide thermoalkaline pretreatment, with a two-fold higher yield than the untreated control. Hydrogen production was stable and methane was not present in the resultant gas. The influence of the hydraulic retention time (HRT) on the maintenance of cascade installation was studied. The maximum daily concentration of hydrogen was achieved at an HRT of 2 days—42.5% H2—and the maximum concentration of methane was 56.1% at an HRT of 6 days. Accumulation of volatile fatty acids was registered in the first step and their depletion was noted in the second one. The obtained values of the cellulose content demonstrated that it was utilized by up to 2.75% in the methanogenic bioreactor at the end of the process. Metagenomics analyses revealed the bacteria Thermocaproicibacter melissae (44.9%) and Clostridium cellulosi (41.9%) participated in the consortium, accomplishing substrate hydrolysis and acidogenesis in the first stage. Less in abundance were Thermoanaerobacterium butyriciformans, Calorimonas adulescens, Pseudomonas aeruginosa and Anaerocolumna chitinilytica. Methanogenesis was performed by an archaeon closely related to Bathyarchaeota (99.5%) and Methanobacterium formicicum. The most abundant bacterial strains in the methanogenic fermenter were Abyssalbus ytuae (30%), Proteiniphilum acetatigenes (26%) and Ruficoccus amylovorans (13%).

Assessment of the properties of mortars made of sorel cement

The purpose of laboratory tests was to determine the effect of sodium silicate and selected hydrophobic agents on the basic physical parameters and freeze-thaw durability of mortars made with Sorel cement in variable proportions. In order to determine the mortars’ parameters, samples of the dimensions of 4x4x16 cm and boards of the diameters of 1x4x16 cm were prepared. Parameters such as water absorption, capillary absorption, compressive and flexural strength and frost resistance were tested. Mortar supplemented with sodium silicate in the quantity of 2.6% of all components demonstrated the best properties. None of the other hydrophobic agents that were used to mitigate the negative effects of water on Sorel cement mortars demonstrated such positive properties. Flexural strength tests of all mortar batches, performed on cuboid samples and boards of the thickness of 1 cm, demonstrated a similar improvement in strength. The lowest value of compressive strength was recorded for the reference batch at 46.6 MPa, whereas the highest value was recorded for the second batch containing sodium silicate, at 49.8 MPa. During the testing of frost resistance, the lowest reduction of compressive and flexural strength was recorded for the reference mortar and for mortar with sodium silicate. All mortars were varied in the MgO/MgCl2 ratio and the total amount of water, the observed effects may be caused by other variables. However it is possible to notice the positive effect of selected hydrophobic agents.

Removal of Lead Using Novel Composite Synthesized from Rice Husk and Used Tea Leaves Extract

Untreated industrial effluents, particularly from tanneries and heavy industries, are the main source of heavy metal pollution, which poses serious environmental risks. Lead is one of the most toxic heavy metals, adversely affects human functioning and accumulates in the environment. This study presents ACUTLaqE (Activated Carbon-Used Tea Leaves Aqueous Extract) as an effective adsorbent for Pb2+ ion removal from their aqueous solution. The composite was synthesized by blending activated carbon from rice husks with a tea extract solution and characterized using SEM, XRD, and FTIR spectroscopy. Batch tests demonstrated that ACUTLaqE is highly efficient, removing about 99% of Pb2+ ions at an adsorbent dose of 2 g/L within 30 minutes. The adsorption data conformed well to the Langmuir isotherm model, suggesting a homogeneous monolayer formation on the composite surface. The qm was 38.61 mg/g, with an RL value close to 0, indicating highly favourable adsorption. Thermodynamic parameters showed negative Gibbs free energy (ΔG⁰) values, reflecting a spontaneous adsorption process. The enthalpy (ΔH⁰) and entropy (ΔS⁰) changes were 66.86 KJmol-1 and 257.12 JK-1mol-1, respectively. The adsorption mechanism involved electrostatic interactions and surface complexation with the composite's hydroxyl and carboxyl groups. These findings suggest that ACUTLaqE is a promising adsorbent material for Pb2+ and potentially other heavy metals removal from industrial effluents.

Competitive Adsorption of Aqueous Cd(II) and Pb(II) Solutions onto Silicas Synthesized with Saponin as Template Agent

The aim of the research was to prepare silica adsorbents using an environmentally friendly pathway, a template synthesis with saponin biosurfactant as a structure-directing agent. The adsorbents prepared in this way exhibit improved adsorption properties while maintaining environmental innocuousness. For the preparation of porous silica, the biosurfactant template sol–gel method was used with tetraethoxysilane as a silica precursor. The silica adsorbents were analyzed by FTIR spectroscopy, nitrogen adsorption–desorption and SEM/EDX microscopy, TEM/HRTEM microscopy, and thermogravimetric analyses. Batch tests were carried out to remediate Pb(II)/Cd(II) ions in single/binary aqueous solutions, and the effect of the surfactant on the adsorption properties was assessed. The optimal adsorption parameters (pH, contact time, initial concentration of metal ions) have been determined. The adsorption was fitted using Langmuir and Freundlich adsorption isotherms and kinetic models. Mathematical modeling of the retention process of Pb(II) and Cd(II) ions from binary solutions indicated a competitive effect of each of the two adsorbed metal ions. The experimental results demonstrated that saponin has the effect of modifying the silica structure through the formation of pores, which are involved in the retention of metal ions from aqueous solutions and wastewater.

Nitrite-driven anaerobic ethane oxidation

Ethane, the second most abundant gaseous hydrocarbon in vast anoxic environments, is an overlooked greenhouse gas. Microbial anaerobic oxidation of ethane can be driven by available electron acceptors such as sulfate and nitrate. However, despite nitrite being a more thermodynamically feasible electron acceptor than sulfate or nitrate, little is known about nitrite-driven anaerobic ethane oxidation. In this study, a microbial culture capable of nitrite-driven anaerobic ethane oxidation was enriched through the long-term operation of a nitrite-and-ethane-fed bioreactor. During continuous operation, the nitrite removal rate and the theoretical ethane oxidation rate remained stable at approximately 25.0 mg NO2–N L−1 d−1 and 11.48 mg C2H6 L−1 d−1, respectively. Batch tests demonstrated that ethane is essential for nitrite removal in this microbial culture. Metabolic function analysis revealed that a species affiliated with a novel genus within the family Rhodocyclaceae, designated as 'Candidatus Alkanivoras nitrosoreducens', may perform the nitrite-driven anaerobic ethane oxidation. In the proposed metabolic model, despite the absence of known genes for ethane conversion to ethyl-succinate and succinate-CoA ligase, 'Ca. A. nitrosoreducens' encodes a prospective fumarate addition pathway for anaerobic ethane oxidation and a complete denitrification pathway for nitrite reduction to nitrogen. These findings advance our understanding of nitrite-driven anaerobic ethane oxidation, highlighting the previously overlooked impact of anaerobic ethane oxidation in natural ecosystems.

Enhanced Biological Nitrate Removal from Groundwater in Humid Tropical Regions Using Corn Cob-Based Permeable Reactive Barriers: A Case Study from Panama

Nitrate contamination in groundwater is a global concern due to its widespread presence and consequential social, environmental, and economic ramifications. This study investigates the efficacy of biological denitrification in a humid tropical setting, utilizing corn cob in batch and column tests to assess nitrate removal under varying conditions. Batch tests demonstrated the nitrate removal efficiencies of 93.14%, 91.58%, 90.77%, and 98.74% for initial concentrations of 22.18 ± 2.82 mg/L, 27.3 mg/L, 69.1 ± 1.2 mg/L and 115.08 ± 1.88 mg/L, respectively. In the column test, the removal efficiency was 99.86%, 87.13%, and 74%, and the denitrification rate was 32.82, 53.43, and 83.53 mg NO3−-N/L d, for a hydraulic retention time (HRT) of 24 h, 16 h, and 7 h, respectively. Predominantly, nitrate removal occurred via biological denitrification, particularly favoring a 24 h HRT. The corn cob effectively removed high nitrate concentrations of up to 115 mg NO3−-N/L. Scanning electron microscopy and Fourier transform infrared spectroscopy revealed surface characteristic changes of the carbon source pre- and post-denitrification. This research sheds light on the potential of biological denitrification using corn cob in humid tropical environments, offering a promising avenue for addressing nitrate contamination challenges in groundwater systems.

A difficult coexistence: Resolving the iron-induced nitrification delay in groundwater filters

Rapid sand filters (RSF) are an established and widely applied technology for the removal of dissolved iron (Fe2+) and ammonium (NH4+) among other contaminants in groundwater treatment. Most often, biological NH4+oxidation is spatially delayed and starts only upon complete Fe2+ depletion. However, the mechanism(s) responsible for the inhibition of NH4+oxidation by Fe2+ or its oxidation (by)products remains elusive, hindering further process control and optimization. We used batch assays, lab-scale columns, and full-scale filter characterizations to resolve the individual impact of the main Fe2+ oxidizing mechanisms and the resulting products on biological NH4+ oxidation. modeling of the obtained datasets allowed to quantitatively assess the hydraulic implications of Fe2+ oxidation. Dissolved Fe2+ and the reactive oxygen species formed as byproducts during Fe2+ oxidation had no direct effect on ammonia oxidation. The Fe3+ oxides on the sand grain coating, commonly assumed to be the main cause for inhibited ammonia oxidation, seemed instead to enhance it. modeling allowed to exclude mass transfer limitations induced by accumulation of iron flocs and consequent filter clogging as the cause for delayed ammonia oxidation. We unequivocally identify the inhibition of NH4+oxidizing organisms by the Fe3+ flocs generated during Fe2+ oxidation as the main cause for the commonly observed spatial delay in ammonia oxidation. The addition of Fe3+ flocs inhibited NH4+oxidation both in batch and column tests, and the removal of Fe3+ flocs by backwashing completely re-established the NH4+removal capacity, suggesting that the inhibition is reversible. In conclusion, our findings not only identify the iron form that causes the inhibition, albeit the biological mechanism remains to be identified, but also highlight the ecological importance of iron cycling in nitrifying environments.

Comparison of perfluoroalkyl substance adsorption performance by inorganic and organic silicon modified activated carbon

Owing to the persistence and increasingly stringent regulations of perfluoroalkyl substances (PFAS), it is necessary to improve their adsorption capacities using activated carbon (AC). However, their adsorption capacities are suppressed by dissolved organic matter (DOM). In this study, two ACs modified with organic silicon (C-OS) and inorganic silicon (C-IS) were synthesized and used for the adsorption of PFAS in raw water (RW). The results showed that the PFAS adsorption capacity of C-IS was much less influenced by DOM than that of the original AC (C-virgin). In RW, perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) adsorption capacities on C-IS were 15.08 and 3.65 times higher than those on C-virgin, respectively. DOM had less influence on the PFOA and PFOS adsorption kinetics of C-IS than C-OS and C-virgin. Under multi-PFAS condition, C-IS also exhibited slower desorption of short-chain PFAS and breakthrough in batch and column tests, respectively. Characterization of the ACs before and after adsorption and independent gradient modelling indicated that hydrogen bond interactions between the O-Si of C-IS and the –COOH or –CSO3H groups of PFAS contributed to PFAS adsorption. Density functional theory calculations demonstrated that the adsorption energy of C-IS was much lower than that of C-OS and C-virgin. The arrangement of PFAS molecules on C-OS was chaotic owing to the hydrophobic siloxane chain, whereas the arrangement of PFAS on C-IS was orderly in multi-layer or semi-micelle status and more favorable to PFAS adsorption. This study provides a new strategy for avoiding adverse effects of DOM on PFAS adsorption.

Investigation of Phosphate Removal from Aqueous Solutions Using Zinc Extraction Waste

It is important for waste management to economically evaluate the solid leach residues released in zinc production facilities and classified as hazardous waste due to the metals they contain, without harming the environment and human health. Although the disposal of these residues often requires special technologies, hazardous wastes are left to the environment or landfills due to the expense of these technologies and the inadequacy of legal sanctions in some cases. For this reason, it is important from an economic and environmental perspective to evaluate these residues and bring them into the industry. In this study, lead cake formed during zinc extraction production, brought from Kayseri Çinkur enterprises, was used. Since this waste contains high amounts of lead as well as zinc and iron, the conditions for removing phosphate from aqueous solutions were investigated. Phosphate removal adsorption isotherms were obtained using the obtained batch test results. Additionally, some thermodynamic quantities regarding phosphate removal were calculated. As a result of the experiment, it was determined that the P removal efficiency from aqueous solutions significantly depends on the solution pH and the dose of waste lead cake. It was also determined that phosphate removal from aqueous solutions obeyed the Langmuir and Freundlich isotherm. Additionally, it was observed that phosphate adsorption equilibrium was established after a period of 120 min. By mixing 100 mg/L phosphate solution with pH 7.69 with 20 g/L lead cake without any addition and contacting for 120 minutes, approximately 74% of the phosphate can be effectively removed by adsorption.

Anaerobic digestion of herbal waste: a waste to energy option.

Herbal waste produced during the manufacturing of herbal products is a potential feedstock for anaerobic digestion due to high amount of organic matter that can be transformed into biogas as an energy resource. Therefore, the present study was undertaken to convert herbal waste produced during the manufacturing of common of Ayurveda products into biogas through anaerobic digestion process using batch test study under controlled mesophilic temperature conditions of 35°C with food to inoculum ratio of 0.75. The maximum biomethane potential (BMP) of 0.90 (gCH4COD/g CODfed) and sludge activity of 0.70 (gCH4-CD/gVSS) was exhibited by WS herbal waste owing to its high chemical oxygen demand (COD) of 4g/g and better solubilization potential of the organic matter showing change in volatile suspended solids (ΔVSS) of 79%. On the other hand, the waste derived from the TA herb, exhibited the least biogas yield of 0.55 (gCH4COD/g CODfed) and sludge activity of 0.40 (gCH4-CD/gVSS), albeit with higher organic matter present. This was due to the possible hindrance of waste solubilization by the presence of lignin. The waste derived from VVL and PE showed intermediate BMP and sludge activity. The methane generation rate constant (k), a key indicator of the biodegradation potential, was also evaluated. The k values showed similar trend as of BMP values ranging from 0.081 to 0.15 d-1 thus indicating the influence of presence of lignin and the change in ΔVSS. The present study proves anaerobic digestion to be an alternative treatment method to be a milestone for management of herbal wastes and can be successfully implemented on real-scale systems.

Determination of trace elements in superalloys by inductively coupled plasma mass spectrometry with micro-reaction pretreatment

Due to complex pretreatment processes and the consumption of large amounts of high-purity chemical reagents, traditional analytical methods for determining trace element concentrations in superalloys face severe challenges. In this paper, a micro-reaction pretreatment method was developed by using a micro-reaction sealed digestion vessel under micro-pressure. The mass of the samples and the volume of acid used to dissolve the superalloys were significantly reduced. The appropriate amount of digestive acid for micro-reaction and three generalized pretreatment methods were studied. The quantitative dilution process was optimized to minimize errors through meticulous weighing procedures using a high-precision balance, and the homogeneity of the samples was verified by using Ni-based superalloy standards and general samples. Sc, Rh, and Re were selected for internal standard correction, and the matrix effect was corrected by the matrix matching method. Moreover, the mass spectral interference caused by polyatomic ions was eliminated by He collision mode. The linear correlation coefficients of the calibration curves were above 0.9995, with linear coefficients ranging from 0.2 to 100 ng/g. The detection limits for the method ranged from 0.0042 to 0.13 μg/g, and the quantification limits ranged from 0.014 to 0.41 μg/g. The results showed the precision and reliability of the newly established green micro-reaction pretreatment scheme for the determination of Ga, As, In, Sn, Sb, Tl, Pb, and Bi in nickel-based superalloys together with inductively coupled plasma mass spectrometry. The micro-reaction test results of the various groups were consistent with those of the traditional methods, and the relative standard deviation (RSD, n = 11) was less than 10 %. In addition to reducing acid consumption and increasing the test solution utilization rate by ten times, the micro-reaction method was much more accessible from cross-contamination and intensive manual work, so it has shown great potential for application in intelligent and automatic batch testing of trace elements in superalloys.

Biogenic Palladium Improved Perchlorate Reduction during Nitrate Co-Reduction by Diverting Electron Flow in a Hydrogenotrophic Biofilm.

Microbial reduction of perchlorate (ClO4-) is emerging as a cost-effective strategy for groundwater remediation. However, the effectiveness of perchlorate reduction can be suppressed by the common co-contamination of nitrate (NO3-). We propose a means to overcome the limitation of ClO4- reduction: depositing palladium nanoparticles (Pd0NPs) within the matrix of a hydrogenotrophic biofilm. Two H2-based membrane biofilm reactors (MBfRs) were operated in parallel in long-term continuous and batch modes: one system had only a biofilm (bio-MBfR), while the other incorporated biogenic Pd0NPs in the biofilm matrix (bioPd-MBfR). For long-term co-reduction, bioPd-MBfR had a distinct advantage of oxyanion reduction fluxes, and it particularly alleviated the competitive advantage of NO3- reduction over ClO4- reduction. Batch tests also demonstrated that bioPd-MBfR gave more rapid reduction rates for ClO4- and ClO3- compared to those of bio-MBfR. Both biofilm communities were dominated by bacteria known to be perchlorate and nitrate reducers. Functional-gene abundances reflecting the intracellular electron flow from H2 to NADH to the reductases were supplanted by extracellular electron flow with the addition of Pd0NPs.

Integrating diffusion dialysis for sustainable acid recovery from ion exchange regeneration stages: Characterization of metal and non-metal ions migration

Seawater mining presents a potential option for recovering the European Union’s Critical Raw Materials (CRMs), but direct extraction from seawater is challenging due to their low concentrations, as most of them are Trace Elements (TEs) (at levels of mg/L or µg/L). Saltworks bitterns (ultraconcentrated brines resulting from the sea salt production process) offer an alternative solution, naturally concentrated up to 40 times more than seawater. These bitterns can be further processed with chelating Ion Exchange (IX) sorbents to selectively extract TEs. However, this process requires an acidic elution stage with strong acids, followed by neutralization, to recover TEs through precipitation, demanding extensive chemicals consumption. Diffusion Dialysis (DD) could be used to recover the excess acid without external reagents, using an acid-resistant Anion Exchange Membrane (AEM). This study evaluates DD through batch and once-through tests for acid recovery from simulated IX eluate generated in the elution stage of TEs (B, Ga, Ge, Co, Sr) recovery from saltworks bitterns.Batch tests achieved high recoveries for HCl (45–50 %) and H2SO4 (30–37 %), being the theoretical maximum attainable recovery equal to 50 %. B and Ge only partially permeated through the membrane (82 % rejection) by a diffusion mechanism in their neutral form (H3BO3(aq), H4GeO4(aq)). Ga, Co and Sr, in cationic form, were highly rejected (>96 %). Permeability followed the order Ga < Sr < Co ≪ Ge < B, due to the relevant charge and size. HCl permeability correlated linearly with concentration, while H2SO4 was inversely proportional. Once-through tests showed higher acid (74 % HCl, 62 % H2SO4) and oxoacid (66 % H3BO3(aq), 52 % H4GeO4(aq)) recovery at a low specific flow rate, or apparent flux, (0.38 L/(m2membrane·h)) due to increased residence time. Water to acid flow rate ratios did not affect species transport when an excess of water was guaranteed. Conversely, an influence was observed when the ratio was below 1, with a minimum at 0.18, where a very low passage of species was observed due to the reduced dilution volume of the dialysate solution (water). A 1D transport model, incorporating the solutes permeabilities determined experimentally, effectively described the system performance, especially for HCl and B, albeit slightly overestimating the other TEs’ transport.

Assessing nitrous oxide emissions from algal-bacterial photobioreactors devoted to biogas upgrading and digestate treatment

Nitrous oxide (N2O) emissions in High Rate Algal Ponds (HRAP) can negatively affect the sustainability of algal-bacterial processes. N2O emissions from a pilot HRAP devoted to biogas upgrading and digestate treatment were herein monitored for 73 days. The influence of the pH (7.5, 8.5, and 9.5), nitrogen sources (100 mg L−1 of N–NO2-, N–NO3-, and N–NH4+) and illumination on N2O emissions from the algal-bacterial biomass of the HRAP was also assessed in batch tests. Significantly higher N2O gas concentrations of 311.8 ± 101.1 ppmv were recorded in the dark compared to the illuminated period (236.9 ± 82.6 ppmv) in the HRAP. The batch tests revealed that the highest N2O emission rates (49.4 mmol g−1 TSS·h−1) occurred at pH 8.5 in the presence of 100 mg N–NO2-/L under dark conditions. This study revealed significant N2O emissions in HRAPs during darkness.

Complementary Field and Laboratory Batch Studies to Quantify Generation Rates of Perfluoroalkyl Acids in a Contaminated Agricultural Topsoil with Unknown Precursors

AbstractSoil microbiome changes and generation rates of per‐ and polyfluoroalkyl substances (PFAS) precursors were studied in a contaminated agricultural field using a combination of field and laboratory batch microcosm studies. 16S rRNA gene amplicon sequencing was used to track how microbial community composition changed over time, while perfluoroalkyl acids (PFAA) generation rates were quantified using a combination of field and batch incubations combined with the direct total oxidizable precursor (dTOP) assay. The study site in Brilon‐Scharfenberg, North Rhine‐Westphalia, Germany, has PFAS contamination in the topsoil (0 to 30 cm) originating from compost. Generation rate constants of these short‐chain PFAA estimated from batch incubations (0.12 to 0.75 1/year) were higher but similar to rate constants from the fields (0.05 to 0.22 1/year). Long‐term field mass discharge data (2009 to 2023) suggest that at least 60 years are needed to remove 99.99% of short‐chain PFAA and their precursors. 16S rRNA gene amplicon sequencing data revealed a major impact of PFAA on the biodiversity of soil microorganisms, with batch‐incubated contaminated soils showing higher richness and diversity indexes than field control soils. However, most of these impacts occurred at lower taxonomical ranks and did not seem to have a prominent impact on the overall structure of the autochtonous microbial communities of the soils where PFAA were produced and accumulated. Overall, our findings demonstrate that well‐controlled aerobic batch test combined with the results of dTOP assay are a suitable approach for estimating short‐chain PFAA generation rates. Additionally, our research suggests that the complete removal of PFAA precursors from topsoil will take decades.

Potential of electrospun fibrous membranes involving tri-n-octylphosphine oxide for selective clearance of uremic toxin p-cresol over urea and creatinine

In this study, various electrospun and electrosprayed fibrous membranes from polyethersulfone (PES) and polyvinylpyrrolidone (PVP) were fabricated, to which a common solvating extractant tri-n-octylphosphine oxide (TOPO) was incorporated. Such TOPO-involved PES membranes were attempted to selectively clear p-cresol, one of trace amounts of small uremic toxins, from simulated serum via hydrogen bonding. Morphological and physicochemical properties of the as-synthesized fibrous membranes were first studied. Batch tests displayed that the equilibrium of p-cresol adsorption on all fibrous membranes were attained within 2 h. Analysis of adsorption isotherms of p-cresol by the Langmuir equation revealed that the adsorption was improved in the presence of TOPO; moreover, the distribution state of TOPO powders along the fibers played an important role in membrane performance. Among the six as-prepared TOPO-incorporated membranes, the highest adsorption capacity of p-cresol in simulated serum at 37oC and pH 7.4 reached to be 21.7 mmol per gram of TOPO. The operational stability of as-prepared fibrous membranes was evaluated by checking their adsorption ability, membrane weight, water contact angle, structural changes by SEM imaging, and PVP dissolution using UV–Vis spectroscopy, both before and after exposure to PBS solution. Crossflow permeation-adsorption of a multicomponent mixture (0.46 mmol/L of p-cresol, 1.33 mmol/L of creatinine, and 38.3 mmol/L of urea) for 4 h indicated that the prepared membranes yielded a high selectivity toward p-cresol against creatinine and urea of 21.2–43.0 and 10.8–18.5, respectively. Hemolysis tests and viability measurements of both human umbilical vein endothelial cells and THP 1 monocytic leukemia cells demonstrated that the proposed configurations of the TOPO-incorporated fibrous membranes were hemo- and bio-compatible. Our results on the composition and systematic design of these fibrous membranes suggested that they can serve as an advanced hemoperfusion unit, maintaining high p-cresol removal and bio-compatibility. These well-designed membrane-based devices could be connected in series with the conventional hemodialysis devices to further improve the overall removal of small uremic toxins.