Soluble Products Research Articles

The characteristics and flocculation mechanisms of SMP and B-EPS from a bioflocculant-producing bacterium Pseudomonas sp. XD-3 and the application for sludge dewatering

In this study, a novel bacterium Pseudomonas sp. XD-3 with bioflocculant-producing capability was identified and characterized. Strain XD-3 produced two kinds of flocculating active substances, soluble microbial products (SMP) and bound extracellular polymers substances (B-EPS). The flocculation efficiency of SMP was about 79.3% and that of B-EPS was 79.9%. Charge neutralization, ion bridging and hydrogen bonding played important roles in the flocculation of SMP, while ion bridging and hydrophobic force dominated the flocculation in B-EPS. Spectral analysis revealed that –OH and –COO- in SMP and B-EPS provided abundant binding sites for ion bridging. The presence of CNH3+ in SMP participated in charge neutralization. The hydrophobic groups of C-(C/H) and OC contributed to the hydrophobic force of B-EPS. In addition, both SMP and B-EPS contained proteins secondary structures that were beneficial for bioflocculation, such as α-helix, three-turn helices, β-sheet and aggregated strands. B-EPS exhibited satisfied sludge dewatering effect, with a water content reduction from 93.66% to 83.9% and a specific resistance to filtration (SRF) reduction from 13.48 × 1012 m/kg to 7.74 × 1012 m/kg. The composite flocculant of B-EPS and Al2(SO4)3 further reduced the SRF to 1.54 × 1012 m/kg at pH 4, CaCl2 dosage 23.3 g/kg, B-EPS 0.93 g/kg and Al2(SO4)3 150 g/kg.

High–level production of a novel alginate lyase (FsAly7) from Flammeovirga sp. for efficient production of low viscosity soluble dietary fiber from sodium alginate

Sodium alginate is one of the most abundant sustainable gum source for dietary fiber production. However, the preparation efficiencies of low viscosity soluble dietary fiber from sodium alginate remain low. Here, a novel alginate lyase gene (FsAly7) from Flammeovirga sp. was identified and high–level expressed in Pichia pastoris for low viscosity soluble dietary fiber production. The highest enzyme production of 3050 U mL−1 was achieved, which is by far the highest yield ever reported. FsAly7 was used for low viscosity soluble dietary fiber production from sodium alginate, and the highest degradation rate of 85.5 % was achieved under a high substrate content of 20 % (w/v). The molecular weight of obtained soluble dietary fiber converged to 10.75 kDa. FsAly7 catalyzed the cleavage of glycosidic bonds in alginate chains with formation of unsaturated non-reducing ends simultaneously in the degradation process, thus altered the chemical structures of hydrolysates. The soluble dietary fiber exhibited excellent properties, including low viscosity, high oil adsorption capacity activity (2.20 ± 0.03 g g−1) and high emulsifying activity (60.05 ± 2.96 mL/100 mL). This investigation may provide a novel alginate lyase catalyst as well as a solution for the efficient production of low viscosity soluble dietary fiber from sodium alginate.

Bio-inoculation with Serratia CP-13 enhances Cd detoxification via modulation of phytohormone, gas exchange attributes and nutrient acquisition in maize cultivars cultivated in Cd-stressed soil

Heavy metals contamination of soil is increasing rapidly due to prompt in urbanization and industrialization. Recently, cadmium (Cd) pollution has emerged as a severe menace to plant and human health, while the use of plant growth promoting rhizobacteria (PGPR) has appeared as an economical approach for bioremediation of Cd toxicity in crop plants. In this study, the effect of Serratia sp. CP-13 inoculation on two maize cultivars in pre-Cd (0, 5, 12, 18, 26, 30 µM) spiked soil was evaluated. The combined effect of soil Cd and CP-13 application was assessed through the analysis of seed germination, plant biomass, phytohormones, gas exchange attributes, antioxidant production, plant Cd, and nutrient uptake in two (Sahiwal-2002, MMRI-Yellow) maize cultivars. Our outcomes exposed that single treatment of Cd-spiked soil significantly downregulates seed germination, plant biomass, plant nutrients, photosynthetic pigments, indole acetic acid (IAA), total protein, proline, total soluble sugar (TSS), stomatal conductance, transpiration rate, net photosynthesis, and antioxidant production, together with upregulating malondialdehyde (MDA), relative membrane permeability (RMP), abscisic acid (ABA), and Cd uptake in maize cultivars. However, this response of the maize crop against Cd-spiked soil was found to be maximal in Sahiwal-2002 at 30 µM Cd. Furthermore, the inoculation of Cd-resistant CP-13 significantly upregulates the plant accumulation of biomass, seed germination, antioxidants, IAA, gas exchange attributes, photosynthetic pigments, plant physiology, and nutrient uptake and downregulates the MDA, RMP, ABA, and root/shoot Cd accretion in two cultivars of maize. Moreover, this CP-13 based upregulation of plant growth was found to be cultivar (Sahiwal-2002) and Cd treatment (30 µM) specific by controlling the accumulation of lipid peroxidation, phytohormone content, and Cd detoxification. Further, our results indicate that the CP-13 might be a promising and cost effective future biofertilizer for bioremediation of soil Cd.

Nontargeted identification of disinfection by-product precursors from soluble microbial products in municipal secondary effluent

As soluble microbial products (SMPs) can serve as precursors for disinfection by-products (DBPs), the release of SMPs from municipal secondary effluent has the potential to increase the health hazards associated with reused water. Nontargeted identification of DBPs precursors from SMPs in municipal secondary effluent was explored in the present research. The hydrophobic (HPO) fraction that constituted the major portion of the SMPs was 48.0%, and the majority of organic SMPs were composed of low molecular weight (LMW) compounds. The results showed that the HPO fraction with MW < 1 kDa component has the highest disinfection by-product formation potentials (DBPFPs). X-ray photoelectron spectroscopy (XPS) results showed that the HPO fraction with MW < 1 kDa component was mainly composed of OC–OH (40.2%) and amide/peptide N (46.7%) functional groups. This finding was in line with the results showing the highest yields of DBPFPs in terms of HAAs (haloacetic acids) and trichloroacetamide (TCAcAm). Ultra-performance liquid chromatography coupled with tandem quadrupole-time-of-flight mass spectrometry (UPLC-Q-ToF-MS) data revealed that phospholipids, fatty acids, fatty acyls-fatty amides, phosphatidylcholine, glycosides, fatty acid esters, glycolipid, and steroids were the main chemical classes in SMPs. Among these chemical classes, phospholipids containing amino acids structures and fatty acids containing carboxyl functional groups with the maximum abundance could promote the formation of HAAs. This research offers a thorough characterization of SMPs derived from municipal secondary effluent. These results enable the implementation of targeted methods to decrease the formation of DBPs by identifying potential precursors of DBPs.

High-Voltage Instability of Vinylene Carbonate (VC): Impact of Formed Poly-VC on Interphases and Toxicity.

Full exhaustion in specific energy/energy density of state-of-the-art LiNix Coy Mnz O2 (NCM)-based Li-ion batteries (LIB) is currently limited for reasons of NCM stability by upper cut-off voltages (UCV) below 4.3 V. At higher UCV, structural decomposition triggers electrode crosstalk in the course of enhanced transition metal dissolution and leads to severe specific capacity/energy fade; in the worst case to a sudden death phenomenon (roll-over failure). The additive lithium difluorophosphate (LiDFP) is known to suppress this by scavenging dissolved metals, but at the cost of enhanced toxicity due to the formation of organofluorophosphates (OFPs). Addition of film-forming electrolyte additives like vinylene carbonate (VC) can intrinsically decrease OFP formation in thermally aged LiDFP-containing electrolytes, though the benefit of this dual-additive approach can be questioned at higher UCVs. In this work, VC is shown to decrease the formation of potentially toxic OFPs within the electrolyte during cycling at conventional UCVs but triggers OFP formation at higher UCVs. The electrolyte contains soluble VC-polymerization products. These products are formed at the cathode during VC oxidation (and are found within the cathode electrolyte interphase (CEI), suggesting an OFP electrode crosstalk of VC decomposition species, as the OFP-precursor molecules are shown to be formed at the anode.

LAG-3 expression in microglia regulated by IFN-γ/STAT1 pathway and metalloproteases.

Microglia are resident innate immune cells in the central nervous system (CNS) and play important roles in the development of CNS homeostasis. Excessive activation and neurotoxicity of microglia are observed in several CNS disorders, but the mechanisms regulating their activation remain unclear. Immune checkpoint molecules are expressed on activated immune cells and regulate their activation in peripheral immunity. However, the expression mechanism of immune checkpoint molecules in activated microglia is still unknown. Here, we analyzed the expression of immune checkpoint molecules in activated microglia using the mouse microglial cell line BV2 and primary cultured microglia. The expression of lymphocyte activation gene-3 (LAG-3), a type of immune checkpoint molecule, was increased in microglia activated by IFN-γ. IFN-γ-induced LAG-3 expression in microglia was suppressed by transfection of siRNA targeting STAT1. LAG-3 has two forms, membrane and soluble, and both forms were upregulated in microglia activated by IFN-γ. The production of soluble LAG-3 was suppressed by treatment with inhibitors of metalloproteinases such as ADAM10 and ADAM17. IFN-γ administration into cisterna magna of mice increased LAG-3 expression in spinal microglia. Furthermore, LAG-3 knockdown in microglia promoted nitric oxide production by IFN-γ. Our results demonstrate that LAG-3 expression in microglia is induced by the IFN-γ-STAT1 pathway and soluble LAG-3 production is regulated via cleavage of membranous LAG-3 by metalloproteinases including ADAM10 and ADAM17.

Assessment of denitrification efficiency and membrane fouling potential in a sulfur-driven membrane bioreactor treating effluent from biological treatment

In this study, any remaining nitrate not eliminated during a biological treatment process with a low C/N ratio was effectively removed using sulfur powder in an autotrophic denitrification membrane bioreactor. Moreover, particular attention was given to investigating the potential for membrane fouling in a sulfur-based denitrification reactor, with a comparative analysis to conventional activated sludge in an aerobic membrane bioreactor. At an influent nitrate concentration of 320 mg/L, the removal efficiency reached 94–98 % within a 4-hour hydraulic retention time and at a reactor temperature of 30 °C. The sulfur-based denitrification reactor exhibited soluble microbial products concentration and specific cake resistance values of 38.3 mg/L and 1.4 × 1013 m/kg, respectively, which were 5.47 and 2.26 times higher than those of conventional activated sludge. Furthermore, it was observed that the supernatant from the sulfur-based denitrification reactor resulted in more significant fouling within the membrane surface.

Effect of external acetate added in aquaculture wastewater on mixotrophic cultivation of microalgae, nutrient removal, and membrane contamination in a membrane photobioreactor

The mixotrophic cultivation of microalgae in wastewater has attracted extensive attention due to its many advantages. In this study, acetate, which can be prepared by hydrolysis of aquaculture waste, was used as exogenous organic matter to promote the growth of Chlorella pyrenoidosa cultured in aquaculture wastewater. Microalgae cultivation was carried out in a membrane photobioreactor (MPBR) with continuous inflow and outflow mode. The results showed that exogenous acetate greatly promoted the mixotrophic growth of C. pyrenoidosa. When the dosage of acetate reached 1.0 g L−1, the relative growth rate of microalgae in the logarithmic stage reached 0.31 d−1, which was 4.4 times that of the control. As a result, exogenous acetate also promoted the removal of nutrients from aquaculture wastewater. During the stable operation stage of the MPBR with acetate added in the influent, an average of 87.41%–93.93% nitrogen and 76.34%–88.55% phosphorus was removed from the aquaculture wastewater containing 19.41 mg L−1 total inorganic nitrogen and 1.31 mg L−1 total inorganic phosphorus. However, it was worth noting that adding exogenous acetate also led to an increase in the membrane resistance of the membrane module in the MPBR. Membrane resistance was mainly composed of internal resistance (Ri) and cake resistance (Rc), and with the increase of acetate content in the influent, their proportion in the total resistance gradually increased. Ri contributed the major membrane resistance and was most affected by acetate dosage. Ri reached 32.04 × 1012 m−1 with 1 g L−1 acetate, which accounted for 69.49% of total resistance. Moreover, with the increase of influent acetate concentration of the MPBRs, both the number of insoluble contaminants and dissolved organic contaminants in the membrane modules increased. In addition, the composition of proteins, polysaccharides, and humus in dissolved organic contaminants was close to that in extracellular polymeric substances and soluble microbial products secreted by microalgae. These results suggested that the membrane fouling of membrane modules was closely related to the algal biomass content in the MPBRs. The above results provided a theoretical basis for reducing membrane fouling of MPBR.

A Mechanistic Model for Hydrogen Production in an AnMBR Treating High Strength Wastewater.

In the global race to produce green hydrogen, wastewater-to-H2 is a sustainable alternative that remains unexploited. Efficient technologies for wastewater-to-H2 are still in their developmental stages, and urgent process intensification is required. In our study, a mechanistic model was developed to characterize hydrogen production in an AnMBR treating high-strength wastewater (COD > 1000 mg/L). Two aspects differentiate our model from existing literature: First, the model input is a multi-substrate wastewater that includes fractions of proteins, carbohydrates, and lipids. Second, the model integrates the ADM1 model with physical/biochemical processes that affect membrane performance (e.g., membrane fouling). The model includes mass balances of 27 variables in a transient state, where metabolites, extracellular polymeric substances, soluble microbial products, and surface membrane density were included. Model results showed the hydrogen production rate was higher when treating amino acids and sugar-rich influents, which is strongly related to higher EPS generation during the digestion of these metabolites. The highest H2 production rate for amino acid-rich influents was 6.1 LH2/L-d; for sugar-rich influents was 5.9 LH2/L-d; and for lipid-rich influents was 0.7 LH2/L-d. Modeled membrane fouling and backwashing cycles showed extreme behaviors for amino- and fatty-acid-rich substrates. Our model helps to identify operational constraints for H2 production in AnMBRs, providing a valuable tool for the design of fermentative/anaerobic MBR systems toward energy recovery.

Modularity impacts cellulose surface oxidation by a lytic polysaccharide monooxygenase from Streptomyces coelicolor

AbstractLytic polysaccharide monooxygenases (LPMOs) catalyze the oxidation of β-(1,4)-linked polysaccharides, such as cellulose, in a reaction that requires an electron donor and H2O2 as co-substrate. Several LPMOs include a carbohydrate-binding module (CBM), which promotes action on insoluble substrates. Herein, a fluorescent labeling technique was used to track LPMO action on microcrystalline cellulose and evaluate the impact of CBMs on the distribution of LPMO activity across the fiber surface. Confocal microscopic images revealed that the distribution of oxidized positions on the cellulose surface was CBM-dependent: fluorescent spots were concentrated in reactions with a CBM-containing LPMO whereas they were more dispersed for a CBM-deficient LPMO variant. The more dispersed oxidation pattern for the CBM-free LPMO coincided with the release of fewer soluble reaction products.

Inhibitory Activity of Natural cis-Khellactone on Soluble Epoxide Hydrolase and Proinflammatory Cytokine Production in Lipopolysaccharides-Stimulated RAW264.7 Cells.

The pursuit of anti-inflammatory agents has led to intensive research on the inhibition of soluble epoxide hydrolase (sEH) and cytokine production using medicinal plants. In this study, we evaluated the efficacy of cis-khellactone, a compound isolated for the first time from the roots of Peucedanum japonicum. The compound was found to be a competitive inhibitor of sEH, exhibiting an IC50 value of 3.1 ± 2.5 µM and ki value of 3.5 µM. Molecular docking and dynamics simulations illustrated the binding pose of (-)cis-khellactone within the active site of sEH. The results suggest that binding of the inhibitor to the enzyme is largely dependent on the Trp336-Gln384 loop within the active site. Further, cis-khellactone was found to inhibit pro-inflammatory cytokines, including NO, iNOS, IL-1β, and IL-4. These findings affirm that cis-khellactone could serve as a natural therapeutic candidate for the treatment of inflammation.

Potential of thermophilic bacteria isolated from cow dung-grass compost for bioethanol production using floral waste

In recent years, various efforts have been invested in producing bioethanol from lignocellulosic biomass (LCB) using thermophilic bacteria. Twelve thermophilic ethanologenic bacteria were isolated from cow dung-grass compost using an enrichment technique, and the isolate, CSD6, which produced the highest bioethanol, was studied further. CSD6 utilized both pentose and hexose sugars producing ethanol, lactic acid and acetic acid as major soluble products and was identified through 16S rRNA gene sequencing as a strain of Geobacillus stearothermophilus. The highest ethanol production was found to be 25.05 mM from 5 g/L glucose, equivalent to 55% of the theoretical ethanol yield at 55 °C and initial pH 7.5. The isolate showed average tolerance to ethanol and acetic acid concentration and initial substrate loading. The bioethanol potential of CSD6 was also studied using autoclave-treated mixed floral waste (FW) as a no-cost substrate. CSD6 produced a maximum of 8.9 mM of bioethanol with a 75.47% decrease in reducing sugars using 20 g/L FW as substrate without any enzymatic pretreatment, indicating the ability of CSD6 to produce bioethanol from easily available substrates.

Performance of a recirculated biogas-sparging anaerobic membrane bioreactor system for treating synthetic swine wastewater containing sulfadiazine antibiotic

Anaerobic Membrane Bioreactor (AnMBR) is an efficient system for treating synthetic swine wastewater (SW). However, the presence of antibiotics in SW discourages the activity of microorganisms, resulting in less pollutants removal and biogas production. In this paper, a recirculated biogas-sparging anaerobic membrane bioreactor system was used to treat swine wastewater containing sulfadiazine (SDZ). The effects of different concentrations of SDZ on the AnMBR system’s performance were explored, in terms of pollutant removal, biogas production, membrane fouling and microbial community. Results indicated that the larger concentration of SDZ triggered a strong suppression in the system’s performance. When treating 1.0 mg/L SDZ, the biogas-sparging AnMBR system achieved about 77 % COD removal and 0.23 L/g CODremoved biogas production, which without SDZ fell to 21 % COD being removed and dropped biogas production by 30 %. As well, the presence of SDZ (1.0 mg L) increased by about half the amount of soluble microbial product (SMP) and extracellular polymeric substances (EPS) with lower protein/polysaccharide ratio and reduced sludge particle size by 49 %. Meanwhile, microbial community analysis revealed that the abundance of Firmicutes increased while Chloroflexi diminished. These jointly contributed to a shorter membrane fouling cycle declining from the initial 23 d to 7 d. Furthermore, the shift from acetoclastic methanogens to hydrogenotrophic methanogens resulted in less methane production due to the presence of SDZ, while the hydrogenotrophic methanogen Methanobacterium promoted the degradation of SDZ. The work showed AnMBR can effectively treat swine wastewater containing antibiotics and provides basis for practical application.

Effect of lysozyme combined with hydrothermal pretreatment on excess sludge and anaerobic digestion

Anaerobic digestion (AD) is widely employed for sludge stabilization and waste reduction. However, the slow hydrolysis process hinders methane production and leads to prolonged sludge issues. In this study, an efficient and eco-friendly lysozyme pre-treatment method was utilized to address these challenges. By optimizing lysozyme dosage, hydrolysis and cell lysis were maximized. Furthermore, lysozyme combined with hydrothermal pretreatment enhanced overall efficiency. Results indicate that: (1) When lysozyme dosage reached 90 mg/g TS after 240 min of pretreatment, SCOD, soluble polysaccharides, and protein content reached their maxima at 855.00, 44.09, and 204.86 mg/L, respectively. This represented an increase of 85.87%, 365.58%, and 259.21% compared to the untreated sludge. Three-dimensional fluorescence spectroscopy revealed the highest fluorescence intensity in the IV region (soluble microbial product), promoting microbial metabolic activity. (2) Lysozyme combined with hydrothermal pretreatment significantly increased SCOD, soluble proteins, and polysaccharide release from sludge, reducing SCOD release time. Orthogonal experiments identified Group 3 as the most effective for SCOD and soluble polysaccharide release, while Group 9 released the most soluble proteins. The significance order of factors influencing SCOD, soluble proteins, and polysaccharide release is hydrothermal temperature > hydrothermal time > enzymatic digestion time.(3) The lysozyme-assisted hydrothermal pretreatment group exhibited the fastest release and the highest SCOD concentration of 8,135.00 mg/L during anaerobic digestion. Maximum SCOD consumption and cumulative gas production increased by 95.89% and 130.58%, respectively, compared to the control group, allowing gas production to conclude 3 days earlier.

Towards a heat‐ and mass‐balanced kinetic model of TATB decomposition

AbstractTATB (1,3,5‐triamino‐2,4,6‐trinitrobenzene) was thermally degraded by two small‐scale analytical methods – simultaneous differential scanning calorimetry and thermogravimetric analysis (SDT) and a hot‐stage microscope with Fourier Transform Infrared (FTIR) analysis capabilities. SDT used ramped heating, isothermal soaking, and thermal pretreatment at various conditions. The heat flow and mass loss were monitored during various treatment conditions to derive chemical decomposition kinetics and Arrhenius parameters. FTIR experiments used isothermal heating, and changes were monitored spectroscopically. Solid samples generated at specific conditions were collected from both methods and were analyzed by DMSO extraction followed by chemical speciation by optical and mass spectrometric methods. Characterization provided the following reaction insights:1. TATB decreases in a sigmoidal pattern in isothermally heated samples. Other soluble products gradually increase in concentration and then abruptly decline in concentration during the second exotherm, such as diamino‐dinitro‐benzofurazan and amino‐nitro‐benzodifurazan.2. FTIR showed gradual changes in the amino and nitro functionality, shifting positions and decreasing intensity for the first 40 min. Then the solid gradually appeared more like an amorphous C with N incorporated, similar to previous studies on thermally degraded TATB‐type materials.3. Extracted residues (DMSO‐soluble components removed) examined by FTIR showed an abrupt change in chemical composition between 40‐ and 45‐min isothermal treatment, indicating early forming solids are different than later forming residues.4. A reliable mass‐ and energy‐balanced global reaction network must include at least two autocatalytic reactions, either in parallel or series, and at least one must have an explicit initiation reaction having a low activation energy.

Interface Engineering Regulation by Improving Self‐Decomposition of Lithium Salt‐Type Additive using Ultrasound

AbstractLithium salt‐type additives have triggered widespread concern because of their excellent film‐forming properties to construct a solid electrolyte interphase (SEI) with high stability and low impedance. However, little attention has been paid to enhancing the utilization efficiency of the expensive lithium salt‐type additives. Herein, the main factor limiting the decomposition of lithium difluoro bis(oxalate) phosphate (LiDFBOP) during the initial SEI formation is clarified. Combining the electrochemical analysis results and quantum chemistry calculations, it is inferred that LiDFBOP preferentially decomposes and generates soluble products accumulating on the graphite surface due to diffusion control kinetics. The excessive aggregation of these products on the electrode inhibits the subsequent continuous decomposition of LiDFBOP. An ultrasound auxiliary method is developed to accelerate the soluble product diffusion and promote the reduction decomposition of LiDFBOP increasing the inorganics content of Li2C2O4 and LiF in the formed SEI. Accordingly, the cell performance is greatly improved compared with that without ultrasound: Li/graphite cells with ultrasound can retain 60.60% of initial capacity after 500 cycles at 1C. This work not only pioneers the study of improving the utilization efficiency of additives contributing to reducing the electrolytes cost but also has direct guiding significance in the targeted regulation of interface properties.

Comparison analysis on biohydrogen production of mesophilic and thermophilic dark fermentation using nickel doped lanthanum-iron oxide nanoparticles as supplementation

In this work, perovskite-structured LaNi0.5Fe0.5O3 nanoparticles (NPs) are successfully synthesized to explore influence of addition amounts on biohydrogen yield. The great potential advantages to improve the biohydrogen production under mesophilic and thermophilic dark fermentation are systematically investigated by a series of experiments. The characterization of physicochemical properties of LaNi0.5Fe0.5O3 NPs are summarized and analyzed. The highest biohydrogen yield 262.55 mL/g of mesophilic dark fermentation is obtained at 100 mg/L LaNi0.5Fe0.5O3 NPs group while under thermophilic condition, the maximum of biohydrogen production is only 182.13 mL/g with 200 mg/L LaNi0.5Fe0.5O3 supplementation, which are higher 50.7% and 91.0% than that of corresponding control groups, respectively. The analysis of soluble microbial products (SMPs) suggests that LaNi0.5Fe0.5O3 NPs can observably enhance the butyrate-type metabolic pathway, being consistent with the raising abundance of Clostridium butyricum in mesophilic fermentation. The extracellular polymer content is significantly increased with appropriate addition of LaNi0.5Fe0.5O3 NPs. The results reveal that the moderate amount of LaNi0.5Fe0.5O3 NPs can even optimize the microbial community structure by increasing the abundance of Clostridium sensu stricto 1 under mesophilic fermentation and Clostridium sensu stricto 7 as well as Longonea under thermophilic fermentation. Eventually, it can be affirmatively concluded that the application of LaNi0.5Fe0.5O3 NPs to dark fermentation contributes to more biohydrogen yield with moderate amounts under both mesophilic and thermophilic conditions. The innovative work of nickel doped lanthanum-iron oxide nanoparticles provides an effective strategy to take the fully advantage of Fe and Ni element for biohydrogen yield.

Analysis of particle size distribution of organic carbon for landfill leachate—implications for sustainable treatment

AbstractBACKGROUNDLandfill leachate has a complex composition requiring experimental support to formulate a sustainable treatment strategy. This study utilized the particle size distribution (PSD) of the chemical oxygen demand (COD) content to assess the profile of biodegradable and inert COD fractions; it also emphasized the functions and benefits of ultrafiltration and nanofiltration modules coupled to an activated sludge process. The evaluation profited from the field data of a landfill site in Istanbul, where the leachate was actually treated in a membrane bioreactor (MBR) plant.RESULTSCOD and total nitrogen levels fluctuated between 10 100–31 200 mg L−1 and 1150–2800 mg L−1, respectively. PSD analysis for COD, conducted at two extremes, displayed similar results, where the majority of the COD was observed to accumulate at the low extremity of the particle size, 70–72% below 2 nm. Therefore, direct membrane filtration of leachate yielded low COD removals that were limited to 9% with ultrafiltration and to 31–35% with nanofiltration. COD fractionation indicated a ratio of 5% for the inert COD in leachate. The permeate COD of ultrafiltration in the existing plant was 2000 mg L−1, much higher than the inert fraction ratio, which was further reduced to 266 mg L−1 by nanofiltration.CONCLUSIONPSD analysis was an integral complement of respirometry for establishing the size‐biodegradation relationships of different COD fractions. It located the majority of soluble COD fractions below 0.55 nm, thus implying the necessity of a biological process. PSD also identified the generation of soluble residual metabolic products, indicating that residual COD escaping treatment would be equally significant to the removal potential of the biodegradable substrate. © 2023 The Authors. Journal of Chemical Technology and Biotechnology published by John Wiley &amp; Sons Ltd on behalf of Society of Chemical Industry (SCI).

Magnetic biochar derived from peanut shells facilitates antibiotic degradation and fouling control in anaerobic membrane bioreactor for antibiotic pharmaceutical wastewater treatment

Anaerobic membrane bioreactor is an attractive option for antibiotic pharmaceutical wastewater treatment, but the unsatisfied treatment performance and membrane fouling issue hindered its wide application. Herein, magnetic biochar (MBC) derived from peanut shells was added to AnMBR for synthetic pharmaceutical wastewater treatment containing sulfamethoxazole (SMX). The results indicated that the treatment performance was improved with 80 % of COD and over 90 % of SMX removal. This can be explained by the adsorption capacity of MBC and improved microbial activity due to the direct interspecies electron transfer enhancement with MBC addition. Membrane fouling was also alleviated due to the adsorption and magnetic bio-effect of MBC, leading to the reduced soluble microbial product (SMP) (22.2 to 6.3 mg/gVSS) and extracellular polymer substance (EPS) concentration (18.9 to 14.2 mg/gVSS), and enlarged particle size (60.6 to 113.4 μm). Microbial diversity analyses indicated that hydrolysis and acidogenesis bacteria (Bacteroidetes and Choloflexi phyla), methanogenic archaea (Methanobacterium and Methanosaeta), and bacteria related to electron transfers (unclassified_f_Geobacteraceae) were enriched due to the presence of MBC. Additionally, the SMX plausible biotransformation pathway and removal mechanism further validated that MBC addition can improve the SMX biodegradation and biotranformation. Importantly, the MBC addition facilitates antibiotic degradation and fouling alleviation of AnMBR, which makes AnMBR a more attractive choice treating for antibiotic pharmaceutical wastewater.

Carboxylation of sulfated cellulose nanocrystals by family AA9 lytic polysaccharide monooxygenases

Lytic polysaccharide monooxygenases (LPMOs) from the auxiliary activity 9 (AA9) family act on cellulose through an oxidative mechanism that improves cellulose saccharification in concert with other cellulolytic enzymes. Degradation and solubilization of cellulose chains are known to take place when various cellulose hierarchies, fibers, nanofibers, and cellulose nanocrystals (CNCs) are subjected to LPMOs, either alone or in combination with other cellulose acting enzymes. The use of LPMOs to modify and prepare CNCs has been proposed mostly in top-down synthesis from larger hierarchies. Here, we attempted a direct surface modification of CNCs with LPMOs with the aim of investigating the role played by the charged sulfate groups on CNCs. Sulfate half-ester groups are introduced during the preparation of CNCs from cellulose using sulfuric acid. It has been proposed that the charged sulfate groups hinder the binding of enzymes or affinity of charged reactants on the surface and hence reduce enzymatic and chemical reaction efficiency. We demonstrate the modification of commercial sulfated CNCs using a family AA9 LPMO. Conductometric titration and spectrometric characterization of the oxidized particles indicate that carboxylation of up to 10% was possible without degradation of the crystals. Unexpectedly, the carboxyl groups could only be introduced to the crystals containing sulfate groups, while desulfated crystals remained unfunctionalized. This was deemed to be due to that the sulfate groups limit the adsorption of the enzymes and hence modulate the cuts facilitated by the enzymes on the surface. This limits the release of chains from the surface and enables the carboxylation of the insoluble substrate rather than the release of the solubilized chains. This study highlights the importance of analyzing both the solid and soluble reaction products to gain insights into the oxidation mechanism. We demonstrated that 10% functionalization suffices for the use of CNCs in coupling chemistry.