High Initial Concentration Research Articles

Enzymatic hydrolysis for the systematic production of second-generation glucose from the dual polysaccharide reserves of an anti-pollutant plant

In this study, the anti-pollutant macrophyte Typha domingensis is exploited for the production of highly concentrated second-generation glucose. A two-stage starch and cellulose enzymatic hydrolysis process is compared for the first time with a single-stage simultaneous starch and cellulose hydrolysis approach, with the former achieving enhanced glucose production, making it more promising for large-scale deployment. The proposed two-stage process is optimized via the Box-Behnken response surface methodology achieving glucose yield values of 74.4% and 71.7% with respect to the starch and cellulose fraction, respectively. Elevated shaking rates are shown to exert a positive effect on both starch and cellulose enzymatic hydrolysis only under high initial substrate concentrations and high initial enzyme to substrate ratios, indicating the importance of accounting for the synergies between key process variables when aiming to increase glucose production. The findings of the presented experimental framework aspire to support future scale-up studies and techno-economic assessments.

Removal of Hazardous Organic Pollutants Using Fly Ash

This study aims to achieve the highest removal efficiency of direct blue dye using a low-cost adsorbent. The adsorption of direct blue 78 dye (DB78) with commercial name (Tubantin blue GLL 300) from a synthetic wastewater using a raw coal fly ash was studied. The ability of coal fly ash (industrial by product) as cost-effective adsorbent to remove dyes from textile wastewater effluent was investigated in detail. A series of batch experiments were conducted in terms of adsorbent dose, contact time, pH, and initial concentration of dye. The raw coal fly ash was characterized by physico-chemical analysis namely; X-ray diffraction (XRD), X-ray fluorescence (XRF) and Brunauer–Emmett–Teller (BET). It was found that the major phases for coal fly ash are quartz and hematite. Loss of ignition percentage and surface area are 36% and 9.6113 m²g^-1 respectively with average particles size 624 nm. The adsorption tests showed that the removal efficiency increases with increasing adsorbent dosage and contact time. Removal efficiency decreases at high initial concentration of direct blue 78 dye. The maximum capacities for dyes removal reached to 99.1% with initial concentration 10 mg/l and fly ash dose 3 g/l. Dyes removal (98.4%) was obtained using initial concentration 20 mg/l and fly ash dose 4 g/l. At higher initial concentration (30 mg/l) using fly ash dose 5 g/l, lower removal efficiency was obtained with 97.2%. The Langmuir isotherm model was shown to have a higher coefficient of determination R² than the Freundlich isotherm model in representing the fly ash adsorption process.

Effectiveness of Adding Extruded Wheat Straw to Poultry Manure to Increase the Rate of Biogas Yield

The work is aimed at increasing the biogas yield rate at biogas plants by means of codigestion poultry manure in combination with extruded wheat straw. To achieve this goal a series of batch tests were performed to study the yields of biogas and CH4 in anaerobic fermentation of mixtures of manure with extruded wheat straw. The working hypothesis of the study was that the wheat straw addition would allow optimizing carbon to nitrogen ratio reducing thus the inhibitory effect of ammonium nitrogen contained in poultry manure on the digestion process. The most important result of the study consisted in the development of a methodology for determining the efficient ratios of extruded straw to poultry manure, at which the highest rate of methane yield was ensured. The two series of the batch assays at 36°C were performed to study the effect of the straw addition to chicken manure at high and low initial volatile solids concentrations. In each series, three types of mixtures were prepared – with 100%, 65% and 35% of poultry manure by volatile solids content in the combination with wheat straw pellets. The significance of the research results was in the fact that the use of extruded straw together with chicken manure could increase the rate of methane yield by almost two times, compared to the fermentation of only poultry manure. The positive effect of wheat straw addition to poultry manure was found in mixtures with a high initial volatile solids concentration, and hence, a high concentration of nitrogen.

Do initial concentration and activated sludge seasonality affect pharmaceutical biotransformation rate constants?

Pharmaceuticals find their way to the aquatic environment via wastewater treatment plants (WWTPs). Biotransformation plays an important role in mitigating environmental risks; however, a mechanistic understanding of involved processes is limited. The aim of this study was to evaluate potential relationships between first-order biotransformation rate constants (kb) of nine pharmaceuticals and initial concentration of the selected compounds, and sampling season of the used activated sludge inocula. Four-day bottle experiments were performed with activated sludge from WWTP Groesbeek (The Netherlands) of two different seasons, summer and winter, spiked with two environmentally relevant concentrations (3 and 30 nM) of pharmaceuticals. Concentrations of the compounds were measured by LC–MS/MS, microbial community composition was assessed by 16S rRNA gene amplicon sequencing, and kb values were calculated. The biodegradable pharmaceuticals were acetaminophen, metformin, metoprolol, terbutaline, and phenazone (ranked from high to low biotransformation rates). Carbamazepine, diatrizoic acid, diclofenac, and fluoxetine were not converted. Summer and winter inocula did not show significant differences in microbial community composition, but resulted in a slightly different kb for some pharmaceuticals. Likely microbial activity was responsible instead of community composition. In the same inoculum, different kb values were measured, depending on initial concentration. In general, biodegradable compounds had a higher kb when the initial concentration was higher. This demonstrates that Michealis-Menten kinetic theory has shortcomings for some pharmaceuticals at low, environmentally relevant concentrations and that the pharmaceutical concentration should be taken into account when measuring the kb in order to reliably predict the fate of pharmaceuticals in the WWTP.Key points• Biotransformation and sorption of pharmaceuticals were assessed in activated sludge.• Higher initial concentrations resulted in higher biotransformation rate constants for biodegradable pharmaceuticals.• Summer and winter inocula produced slightly different biotransformation rate constants although microbial community composition did not significantly change.Graphical abstract

Clinical features and outcome of acquired myasthenia gravis in 94 dogs.

BackgroundFactors known to be associated with outcome of acquired myasthenia gravis (MG) in dogs are limited.Hypothesis/ObjectivesOf dogs with MG, advancing age and comorbid neoplasia are associated with poor long‐term prognosis and low rates of remission.AnimalsNinety‐four client‐owned dogs with MG diagnosed by acetylcholine receptor antibody (AChR Ab) assay between 2001 and 2019 from a university clinic and 3 private clinics in the United States.MethodsCases were retrospectively evaluated and data were collected to determine clinical signs, treatment, and response to therapy defined by means of a clinical scoring rubric. Immunological remission was defined as a return of the AChR Ab concentration to <0.6 nmol/L. Multivariable binary logistic regression analysis was used to identify clinical criteria predicting remission.ResultsAn anticholinesterase drug was used to treat 90/94 (96%) dogs, which in 63/94 (67%) was the sole treatment; other drugs included immune modulators. Clinical remission (lack of clinical signs ≥4 weeks after treatment cessation) was observed in 29 (31% [95% confidence interval (CI): 22.4‐40.8%]) dogs, clinical response (lack of clinical signs on treatment) in 14 (15% [95% CI: 9.0‐23.6%]) dogs, clinical improvement (on treatment) in 24 (26% [95% CI: 17.8‐35.2%]) dogs, and no clinical improvement in 27 (29% [95% CI: 20.5‐38.6%]) dogs. Immunological remission was observed in 27/46 (59%) dogs, with clinical remission in all 27. Younger age (P = .04) and comorbid endocrine disease (P = .04) were associated with clinical remission. Initial AChR Ab concentration (P = .02) and regurgitation (P = .04) were negatively associated with clinical remission.Conclusions and Clinical ImportanceClinical remission in MG is less likely in older dogs and dogs presenting with regurgitation or high initial AChR Ab concentration, but more likely in younger dogs and dogs with comorbid endocrine disease.

Banana stem based activated carbon as a low-cost adsorbent for methylene blue removal: Isotherm, kinetics, and reusability

A low-cost activated carbon from the banana stem (ACBS) was produced to contribute to environmental preservation in removing methylene blue from wastewater. It is originated from abundant agricultural waste and produced at moderate pyrolysis temperature and short pyrolisis time. In the ACBS production, the banana stem was impregnated with H3PO4 solution as the activating agent and followed by pyrolysis at 400 °C for a rapid time of 15 min. The treatment significantly improved the ACBS surface area to 837.453 m2/g. The influence of the ACBS dose and initial concentration of dye solution at various contact times were investigated in this study. The utilization of ACBS in low doses exhibited high removal efficiency of methylene blue (0.05 to 0.3 g/100 mL). It can remove methylene blue completely in 90 min of adsorption with an initial concentration of 50 g/mL. High removal efficiencies are still also demonstrated at higher initial concentrations with 99.762% removal for the initial concentration of 200 g/mL. Equilibrium adsorption data had the best agreement to the Freundlich isotherm model and pseudo-second-order kinetics model. It is predicted that ACBS has a maximum adsorption capacity of 101.01 mg/g. ACBS is an environmentally benign and favorable adsorbent in methylene blue removal and also effective for repeated usage up to 6 consecutive times with no desorption step.

Morphological Analysis of PSMA/PEI Core-Shell Nanoparticles Synthesized by Soap-Free Emulsion Polymerization.

Emulsion polymerization presents the disadvantage that the physical properties of polymer particles are altered by surfactant adsorption. Therefore, in the soap-free emulsion polymerization method, a hydrophilic initiator is utilized while inducing repulsion among particles on the polymer particle surface, resulting in stable polymer particle production. In this study, we developed a methodology wherein spherical and uniform poly(styrene-co-maleic anhydride) (PSMA)/polyethyleneimine (PEI) core–shell nanoparticles were prepared. Further, their morphology was analyzed. During PSMA polymerization, the addition of up to 30% maleic anhydride (MA) resulted in stable polymerization. In PSMA/PEI nanoparticle fabrication, the number of reactants increased with increased initial monomer feed amounts; consequently, the particle size increased, and as the complete monomer consumption time increased, the particle distribution widened. The styrene (St) copolymer acted as a stabilizer, reducing particle size and narrowing particle distribution. Furthermore, the monomers were more rapidly consumed at high initiator concentrations, irrespective of the initiator used, resulting in increased particle stability and narrowed particle distribution. The shell thickness and particle size were PEI feed ratio dependent, with 0.08 being the optimal PEI-to-MA ratio. The fabricated nanoparticles possess immense potential for application in environmental science and in chemical and health care industries.

Single and ternary competitive adsorption-desorption and degradation of amphenicol antibiotics in three agricultural soils

The widespread usage of veterinary antibiotics results in antibiotic contamination and increases environmental risks. This study was evaluated the single and ternary competitive adsorption-desorption and degradation of three amphenicol antibiotics (AMs): chloramphenicol (CAP), thiamphenicol (TAP), and florfenicol (FF) in three agricultural soils. The adsorption capacity of amphenicol antibiotics in the soil was weak, and the Kf value was in the range of 0.15–3.59 μg1-1/nL1/n kg−1. In the single adsorption-desorption experiment, the ranked order of adsorption capacity was TAP > FF > CAP. However, in the ternary competitive adsorption experiment, the order was changed to be CAP > FF > TAP. The degradation of AMs in soils was performed at various conditions. All AMs were vulnerable to microbial degradation in soils. A higher initial concentration would reduce the degradation rate and enhance the persistence of AMs in soil. The degradation of AMs was positively influenced by changes in soil moisture content and culture temperatures up to 30 °C and decreased at higher temperatures. An equation was used to predict the leachability of AMs in soils and assess their risk to the water environment. The weak adsorption capacity and poor persistence of FF indicated that it may have a strong effect on groundwater based on the equation. It is imperative to further assess the biological impacts of FF at environmentally relevant concentrations given its mobility and extensive use in the livestock industry.

Immobilization of Spathaspora passalidarum NRRL Y-27907 in Calcium Alginate Aiming the Production of Second-Generation Ethanol

The immobilization of S. passalidarum in calcium alginate beads for second-generation ethanol production (2G ethanol) was evaluated in a medium that simulated a hemicellulosic hydrolysate of sugarcane bagasse pretreated with diluted sulfuric acid in terms of sugar composition. Three sets of sequential batch fermentations (SBF) were carried out with free cells or immobilized cells in high (HSC) and moderate (MSC) initial sugar concentration (120 and 70 g/L, respectively). SBF were characterized by five consecutive batches performed in shaker, at 30 °C and 110 rpm. Better results were observed for the SBF with immobilized cells in MSC medium when compared to HSC (Y’P/S of 0.27 ± 0.02 and 0.19 ± 0.03 g/g, respectively), in the second batch cycle. The value for YP/S in MSC was similar to the obtained with free cells (0.30 ± 0.02 to 0.33 ± 0.02 g/g). However, QP was lower for MSC with immobilized cells, reaching 0.81 ± 0.04 g/L.h in the second batch, while for free cells the QP varied from 1.06 ± 0.02 to 1.16 ± 0.22 g/L.h. A technique for determining the concentration of immobilized cells in the alginate beads was applied, which made it possible to determine the specific rates for the SBF performed. According to the results obtained, it was possible to demonstrate that S. passalidarum can be immobilized in calcium alginate and reused through SBF, with performance similar to free cells, which can be a good strategy for fermentation of hemicellulosic hydrolysates.

Optimization of electrochemical activation of persulfate by BDD electrodes for rapid removal of sulfamethazine

Boron-doped diamond electrodes have been employed for the removal of sulfamethazine (SMZ) from water by electrochemical activation of persulfate (EO/BDD-PS). A set of experiments with a central composite design (CCD) was conducted to optimize the operating parameters such as persulfate dose, solution pH, and current density by response surface methodology (RSM). The experimental results indicated a rapid degradation of SMZ even at high initial concentrations. For instance, complete degradation of 50 mg L−1 of SMZ was attained after 15 min at the optimum operating conditions (persulfate loading = 0.40 g L−1, pH = 4, and current density = 21 mA cm−2). The oxidation mechanism of EO/BDD-PS process was studied based on the reactive oxidant species (ROS) revealing that both (OH) and ▪ contributed to the degradation of SMZ in the EO/BDD-PS system. Furthermore, the oxidation pathway has been proposed by the suspect screening and tandem mass spectrometry analysis. The performance of EO/BDD-PS showed faster SMZ degradation than electro-Fenton and anodic oxidation processes using the same BDD electrochemical reactor under the same conditions. Furthermore, we provided a cost estimation study revealing that a full-scale application of the EO/BDD-PS system for the treatment of similar contaminated water costs about $2.23 m-3.

Analysis of Flexural Vibrations of a Piezoelectric Semiconductor Nanoplate Driven by a Time-Harmonic Force.

The performance of devices fabricated from piezoelectric semiconductors, such as sensors and actuators in microelectromechanical systems, is superior; furthermore, plate structures are the core components of these smart devices. It is thus important to analyze the electromechanical coupling properties of piezoelectric semiconductor nanoplates. We established a nanoplate model for the piezoelectric semiconductor plate structure by extending the first-order shear deformation theory. The flexural vibrations of nanoplates subjected to a transversely time-harmonic force were investigated. The vibrational modes and natural frequencies were obtained by using the matrix eigenvalue solver in COMSOL Multiphysics 5.3a, and the convergence analysis was carried out to guarantee accurate results. In numerical cases, the tuning effect of the initial electron concentration on mechanics and electric properties is deeply discussed. The numerical results show that the initial electron concentration greatly affects the natural frequency and electromechanical fields of piezoelectric semiconductors, and a high initial electron concentration can reduce the electromechanical fields and the stiffness of piezoelectric semiconductors due to the electron screening effect. We analyzed the flexural vibration of typical piezoelectric semiconductor plate structures, which provide theoretical guidance for the development of new piezotronic devices.

Upgrading of the aqueous product stream from hydrothermal liquefaction: Simultaneous removal of minerals and phenolic components using waste-derived hydrochar

We investigated the co-adsorption of AAEM and phenolic components onto hydrochar prepared from the organic fraction of MSW. HCl washing of the char removed more AAEM (up to 1 g L−1) than phenols from the hydrochar and improved the oxygen content from 21.31% to 24.9%. A relationship between the number and type of functional groups of phenolic components determined the order of adsorption: guaiacol > phenol > vanillyl alcohol > resorcinol. For AAEM the order of adsorption was Ca2+ (103 mg g−1) > K+ (95.7 mg g−1) > Na+ (8.7 mg g−1) > Mg2+ (3.4 mg g−1). Removal efficiency increased with an increase in initial adsorbate concentration with values of 94, 94, 91 and 91% (base on original mass present) obtained for Ca2+, K+, Mg2+, and Na+, respectively. Hydrochar could remove 100% of guaiacol, phenol and resorcinol present and 61% of vanillyl alcohol in the presence of AAEMs. The Dubinin-Radushkevich isotherm best fitted the multilayer adsorption of phenolic components with a calculated qmax of 68.7 mg g−1 and 50.3 mg g−1 for vanillyl alcohol and resorcinol respectively. Henry's law best described the adsorption of AAEMs. A mass transfer analysis showed that film diffusion controls the adsorption process at low adsorbate concentrations (Bi < 100). At higher initial sorbate concentration, the rate of transport was controlled by intra-particle diffusion.AAEM components were exchanged for phenolic components to form stronger hydrogen bonds, resulting in initial preferential adsorption of phenolics with AAEM only adsorbing at higher initial concentrations.

Stormwater Gravel-Peat Infiltration Filter – An Ecohydrological Technology with Good Urban Design

Urban stormwater flooding and pollution are severe issues due to connected impervious surfaces. Over recent decades, solutions to these issues have been towards stormwater source control measures. We developed an innovative cost-efficient stormwater infiltration filter, made of gravel-peat mixture and geotextile. Laboratory column tests were conducted to compare a range of volumetric ratios of gravel (limestone and silica) to peat regarding their heavy metal removal efficiency (RE). The tested heavy metals were cadmium, lead and zinc. All ratios had a high RE (95.9%-100%), despite very high initial metal concentrations. The 5LG:1P mixture (i.e., volumetric ratio of limestone gravel to peat was 5:1) had the highest RE (99.6%-100%) and is suggested as a good candidate for implementation. If a longer-term use is required, a 5SG:10LG:3P mixture (i.e., volumetric ratio of silica gravel, limestone gravel, and peat of 5:10:3) is recommended as it kept the high heavy metal RE with a lower clogging potential and lower cost than the 5LG:1P mixture. The most convenient but expensive filter material with high RE is limestone gravel alone. Finally, we proposed two field designs for implementing the infiltration filter, which incorporate concepts of “treatment train” and “good urban design”. We also provided some suggestions for the installation of gravel-peat infiltration filters.

Generation of Nano Bubbles Using Cavitation Technique and Monitoring of Strawberry Growth by the Generated Nano Bubbles

In this study, nano bubbles (NBs) of around 100 nm size were generated by using GoodSam-NB generator (made by S company) which utilizes cavitation technique. The generated NBs were directly applied to the strawberry cultivation process to monitor the productivity of strawberry. When the aqueous nutrient solution with NBs was supplied to the strawberry culture medium, it had a slightly higher initial concentration of dissolved oxygen (DO) compared to the nutrient solution prepared with ordinary groundwater at a concentration of about 9 mg/L and did not decrease over time. In other words, NBs helped to supply DO to support the development of roots in the early stage of strawberry's growth, thereby promoting the overall growth of strawberries. After feeding the NBs nutrient solution, the nitrate concentration of the discharged solution was analyzed. The concentration of the nitrate in the effluent was reduced, hence the growth of strawberry was promoted. It can be concluded that the DO contained in aqueous nutrient solution with NBs helped the nitrate to be smoothly taken from the soil.

Central Composite Design: a Response Surface Methodology Approach in Biodegradation of Textile Dye Wastewater

Objectives : This study evaluated and identified the removal of colors and chemocal oxygen demands from thextile dye effluents by Bacillus cereus isolated from the local textile wastewater treatment plant.Methods : Central composite design (CCD) from response surface methodology (RSM) was applied in order to achieve the optimized treatment process condition for the textile dyes wastewater degradation. Two-level of three process parameters with six center points resulted a total of twenty runs of experiments were performed. Bacterial inoculum (-1,+1) (%, v/v), agitation (-1, +1) (rpm), and pH (-1, +1) were tested.Results and Discussion : During the ten days of biodegradation process, highest decolourization achieved was 88.67% with low pH and agitation; and medium level of initial concentration of bacterial inoculum. Highest chemical oxygen demand (COD) removal was achieved with 99.20% from high pH (pH 10), low agitation (100 rpm) and high initial concentration of bacterial inoculum (15%, v/v).Conclusions : The biological treatments was able to remove colour and chemical oxygen demand with application of CCD, giving the optimum settings of the three process parameters studied.

Removal of heavy metal ions form acidic electrolyte for stainless steel electropolishing via adsorption using Polish peats

The use of natural materials for wastewater treatment is a rapidly evolving issue. Natural materials are often low-cost or waste materials, and they are readily available. In the case of industrial wastewater treatment, the use of natural sorbents for the removal of heavy metals has shown positive results for many of the materials tested. However, there are ample reports in the literature of successes based solely on prepared solutions and laboratory trials, which may not actually be as effective when applied under industrial conditions. In the present work, the possibility of using Polish peat from 5 health resorts (Połczyn Zdrój, Goczałkowice Zdrój, Wieniec Zdrój, Kamień Pomorski and Kołobrzeg) as a sorbent for heavy metals in industrial wastewater from the steel electropolishing process is investigated. The materials were characterized and then sorption tests using both laboratory and industrial wastewater solutions were performed. The peat used turned out to be an effective material for both model laboratory and industrial wastewater characterized by high initial concentrations of metals such as iron, chromium, nickel, and copper. Removal rate for initial concentration of 1000 mg/dm3 was 99% for chromium and iron, and 66% for nickel and cooper. The total removal capacity was 30.7 mg/g and indicated the following order Fe(III) > Cr(III) > Cu(II) > Ni(II) in the wide range of industrial electrolyte for stainless steel electropolishing. The method of conducting the research and characteristics of the materials open up new opportunities for removing heavy metal ions in an acidic environment without prior pH correction.

Removal of Phenol from Aqueous Solution by Adsorption onto Baobab Fruit Shell Activated Carbon: Equilibrium and Kinetics Studies

Phenol compounds are considered one of the major problems faced by many countries owing to their release in wastewaters from various industries. These pollutant compounds are harmful to marine life and human beings. Therefore, in the present study, Baobab Fruit Shells (BFS) were used as a precursor for the production of activated carbons for the removal of phenol. The chemical activation of BFS using ZnCl2, H3PO4, and KOH with an impregnation ratio of 1:1 at 500 C for 1 h in Nitrogen (N2) atmosphere was investigated. The effects of these chemicals on the performances of the prepared activated carbons (yield, surface area, adsorption properties) were studied. Fourier transform infrared (FT-IR), scanning electron microscope (SEM), X-ray diffraction (XRD), and N2 adsorption analyses were performed for the characterization of BFS-ACs. SEM results showed that porous structures were formed on the surface of different sizes. FTIR analyses show the presence of different surface groups on the activated carbons. The highest BET surface area and micropore volume were obtained by KOH with 1029.435 m2/g and 0.369 cm3/g, respectively. The developed BFS-ACs were used for the removal of phenol from the aqueous solution. The results indicated KOH in terms of adsorption and efficiency showed better results with a maximum adsorption capacity of 36.90 mg/g at a higher initial concentration (600 mg/L). The adsorption rate of phenol by BFS-ACs was rapid and more than 95.02 % phenol could be absorbed by KOH-AC within the initial 15 min. Phenol adsorption behavior can be described by the Langmuir isotherm model and the pseudo-second-order kinetics. This study provided an effective source that could be used in the production of activated carbon for the treatment of wastewaters as it could be attained at a low cost.

Calculations of the Average Number of Radicals per Particle in Emulsion Polymerization

In emulsion polymerization, the free radicals enter the particles intermittently from the aqueous phase. The number of radicals per particleis given by the Smith-Ewart recursion relation which balances the rate of radical entry into, the rate of radical exit from and the rate of radical termination inside the particle. Models for emulsion polymerisation are based on the 0-1 kinetics or the pseudo-bulk kinetics. Small particles, low initiator concentrations and large number of particles favour the 0–1 kinetics, whereas the large particles, high initiator concentrations and small number of particles will favour pseudo-bulk kinetics. A given polymerization system may exhibit both these kinetic behaviours, initially following the 0-1 kinetics and during the later stages of polymerization following the pseudo-bulk kinetics. The aim of this work is to calculate the time dependent values of the average number of radicals per particle in emulsion polymerization for the pseudo-bulk kinetics.

Modeling the anaerobic digestion of wastewater sludge under sulfate-rich conditions.

Anaerobic digestion (AD) is a biological treatment process to stabilize organic solids and produce biogas. If present, sulfate is reduced to sulfide by anaerobic sulfate-reducing bacteria and the sulfide can be toxic to anaerobic microorganisms. Here, the effect of high initial sulfate concentration on AD of wastewater sludge was investigated using lab-scale batch experiments. Additionally, a systematic mathematical modeling approach was applied for insight into the experimental results. Cumulative biogas and methane production decreased with increasing initial sulfate doses (0-3.300mgSL-1 ). The correlation between the sulfate dose and methane production was consistent with theoretical predictions and model results, indicating no toxic effect of sulfide on methane production. The carbon dioxide content in the biogas decreased linearly with the increasing sulfate dose, which is consistent with the model-predicted behavior of the bicarbonate and hydrogen sulfide buffering system. The examined high sulfate concentrations resulted in no clear negative effects on the COD removal or VSS destruction of the wastewater sludge, indicating negligible inhibition by sulfide toxicity. Even considering the possibility of ferrous sulfide precipitation and the low model estimates of residual sulfide concentration the residual sulfide concentration was higher than reported concentrations that trigger process inhibition. PRACTITIONER POINTS: The effect of sulfate loading on anaerobic digestion of waste activated sludge was characterized. The stoichiometry of sulfate reduction allows accurate prediction of CH4 loss. High sulfate levels (up to 3300mg/L as S) did not affect COD/VSS removal. Sulfide formation increases effluent COD; often misinterpreted as sulfide toxicity. Correcting COD for sulfide's contributions is crucial for results interpretation.

Dysnatremia and 6-Month Functional Outcomes in Critically Ill Patients With Aneurysmal Subarachnoid Hemorrhage: A Prospective Cohort Study.

To investigate the association between plasma sodium concentrations and 6-month neurologic outcome in critically ill patients with aneurysmal subarachnoid hemorrhage. Prospective cohort study. Eleven ICUs in Australia and New Zealand. Three-hundred fifty-six aneurysmal subarachnoid hemorrhage patients admitted to ICU between March 2016 and June 2018. The exposure variable was daily measured plasma sodium. None. Six-month neurologic outcome as measured by the modified Rankin Scale. A poor outcome was defined as a modified Rankin Scale greater than or equal to 4. The mean age was 57 years (± 12.6 yr), 68% were female, and 32% (n = 113) had a poor outcome. In multivariable analysis, including age, illness severity, and process of care measures as covariates, higher mean sodium concentrations (odds ratio, 1.17; 95% CI, 1.05-1.29), and greater overall variability-as measured by the sd (odds ratio, 1.53; 95% CI, 1.17-1.99)-were associated with a greater likelihood of a poor outcome. Multivariable generalized additive modeling demonstrated, specifically, that a high initial sodium concentration, followed by a gradual decline from day 3 onwards, was also associated with a poor outcome. Finally, greater variability in sodium concentrations was associated with a longer ICU and hospital length of stay: mean ICU length of stay ratio (1.13; 95% CI, 1.07-1.20) and mean hospital length of stay ratio (1.08; 95% CI, 1.01-1.15). In critically ill aneurysmal subarachnoid hemorrhage patients, higher mean sodium concentrations and greater variability were associated with worse neurologic outcomes at 6 months, despite adjustment for known confounders. Interventional studies would be required to demonstrate a causal relationship.