Levels Of Initial Concentration Research Articles

Plant-synthesis of co-doped tin dioxide nanocomposite with magnetic activity and its photocatalytic performance assessment on dyes and pesticides

The hydrothermal method was used to introduce different amounts of Praseodymium ion (Pr3+) (1, 3, 5, 7, 9, and 11 at.%) and Yttrium ion (Y3+) (1, 3, 5, 7, 9, and 11 at.%) into existing SnO2 nanoparticles. A novel nanocomposite was created by combining Fe3O4 and SnO2:Pr3+,Y3+ nanoparticles, resulting in a material with magnetic properties, i.e., Fe3O4/SnO2:Pr3+,Y3+, named FPYS. Subsequently, the hydrothermal synthesis approach was utilized to produce nanocomposites of FPYS in the presence of plant extract. The photodecomposition efficiency of as-synthesized nanocomposite was studied with some selected dyes and pesticides under 50W LED light. The present study focused on experimentally optimising the key parameters like the initial concentration, photocatalyst quantity, photocatalyst reuse, and pH level. By employing the Langmuir-Hinshelwood model, we successfully calculated the rate at which RhB, MB, 2,4-DCP, and MB undergo photocatalytic degradation under optimal conditions (pH = 7, pollutant concentration = 8 ppm, volume of pollutants = 20 mL, and photocatalyst amount = 3 mg). The model showed that MB, RhB, 2,4-DCP, and TCAA have k values of 0.061, 0.062, 0.051, and 0.036 min−1, respectively. The breakdown rate for MB dye was 81% and for RhB dye was 78% with nanocomposite made in the presence of 2 mL of Parkia speciosa extract, which was subjected to LED radiation for 150 min at pH 7. The degradation rates of 2,4-DCP and TCAA differed, i.e., the former was degraded by 68% and the latter by 52%. Pr3+ and Y3+ ions co-doped with SnO2 enhanced the photocatalytic degradation of dyes and pesticides.

Self-regenerable oxygen system using microalgae-bacterial consortium for ammonium removal from wastewater

This study investigated self-regenerable oxygen system using microalagae-bacterial consortium for ammonium removal from wastewater and its kinetic modeling based on a combined mechanistic and empirical approach. By mechanistic modeling using a simple microalgal-bacterial Monod model, based on algal growth due to NH4+, NO3− and NO2−, the nitrogen and DO profiles were accurately predicted under different nitrogen conditions (low, medium, and high NH4+ concentrations). The mathematical modeling results showed that sufficient oxygen was available for nitrification at low initial NH4+ ammonium concentration levels, even when dual nitrogen substrate (NH4+–NO2−, NH4+–NO3− or NO2−–NO3−) or all three in combination (NH4+–NO2−–NO3−) were used, compared with high initial ammonium concentration levels. The DO profile was successfully used to monitor N transformation and N uptake in the PSBR based on net O2 uptake rate, O2 production rate, and O2 saturation profile. By empirical modeling of the data obtained, the actual O2 produced by microalgae with the different N species was calculated based on N mass balance and empirical equations. The empirical model further revealed that low NH4+ concentration levels (up to 82.5 mg N/L) favored successful nitrification due to the sufficient production of O2 in the system. However, NH4+ concentration in the range 82.5–132.5 mg N/L affected the nitrification efficiency due to insufficient O2 produced in the system, whereas high ammonium concentration results in nitritation/partial nitrification due to the high demand of O2 by AOB and inhibition in the growth of NOB.

Hydrogeochemical changes with emphasis on trace elements in an artesian well before and after the September 8, 2018 Ms 5.9 Mojiang Earthquake in Yunnan, southwest China

Most groundwater geochemical studies associated with earthquakes have focused on changes in major ions and radon concentration. However, trace elements have also shown a dramatic response to earthquakes and attracted increasing attention. In this study, hydrochemical and water level changes were detected by an artesian well (DZ well) in Yunnan, China, during the 2018 Ms 5.9 Mojiang earthquake. The results show that the major and trace element concentrations changed considerably before and after the earthquake, which were attributed to the mixing of water from different aquifers due to the earthquake-induced alteration of permeability through wavelet analysis of continuous monitoring data and coseismic static strain. In addition, Self-Organizing Map (SOM) and K-means clustering algorithms were used to classify all water samples with 10 trace elements as variables, and the results showed that samples collected in pre- and post-earthquake can be categorized as two groups, showing a significant difference. We argue that the response of trace elements remains unaffected by their initial concentration levels. Notably, both high- and low-concentration trace elements (e.g., Cs, Rb, V, etc.) exhibit discernible changes in response to the Ms 5.9 Mojiang earthquake. These observations corroborate the efficacy of clustering methodologies in delineating seismic-induced concentration shifts and furnish fresh insights into the anomalous behavior of trace elements during the earthquake.

Malachite green and methylene blue dye removal using modified bagasse fly ash: Adsorption optimization studies

Utilizing Bagasse Fly Ash (BFA) as an adsorbent, a byproduct from the sugar industry, proved effective in removing a mixture of Malachite Green and Methylene Blue dyes from aqueous solutions. To enhance its efficacy, the fly ash underwent chemical modification and underwent detailed characterization using FTIR, XRD, SEM, and TGA analyses. Subsequently, adsorption studies were conducted to optimize critical parameters—initial dye concentration, contact time, and pH levels—employing a Mixed-Level Factorial design to pinpoint the most favorable conditions for efficient dye removal. The modified Bagasse Fly Ash (BFA) resulted in a maximum adsorption capacity of 18.75 mg/g (71.5 %) for Malachite Green and 15.5 mg/g (67.2 %) for Methylene Blue at initial dye concentration of 100 mg/L, pH of 9.6, and time of 51.5 min. Analysis of the sorption data involved rigorous application of both Langmuir and Freundlich isotherm models, revealing a strong fit of the linear representation to the data for both dyes. Specifically, R2 values of 0.97 and 0.93 were observed for Malachite Green, while notably higher values of 0.99 and 0.96 were obtained for Methylene Blue, affirming an excellent model-data agreement. Additionally, a kinetic study revealed that the dye adsorption process (MB and MG) followed the pseudo-second-order kinetic model (R2 > 0.99), indicating that chemisorption as dominant adsorption mechanism and providing valuable insights into the dynamic behavior of the process.

Boosted micropollutant removal over urchin-like structured hydroxyapatite-incorporated nickel magnetite catalyst via peroxydisulfate activation

In this work, urchin-like structured hydroxyapatite-incorporated nickel magnetite (NiFe3O4/UHdA) microspheres were developed for the efficient removal of micropollutants (MPs) via peroxydisulfate (PDS) activation. The prepared NiFe3O4/UHdA degraded 99.0 % of sulfamethoxazole (SMX) after 15 min in 2 mM PDS, having a first-order kinetic rate constant of 0.210 min−1. In addition, NiFe3O4/UHdA outperformed its counterparts, i.e., Fe3O4/UHdA and Ni/UHdA, by giving rise to corresponding 3.6-fold and 8.6-fold enhancements in the SMX removal rate. The outstanding catalytic performance can be ascribed to (1) the urchin-like mesoporous structure with a large specific surface area and (2) the remarkable synergistic effect caused by the redox cycle of Ni3+/Ni2+ and Fe2+/Fe3+ that enhances multipath electron transfers on the surface of NiFe3O4/UHdA to produce more reactive oxygen species. Moreover, the effects of several reaction parameters, in this case the initial solution pH, PDS dosage, SMX concentration, catalyst loading, co-existing MPs and humic acid level on the catalytic performance of the NiFe3O4/UHdA + PDS system were systematically investigated and discussed in detail. The plausible catalytic mechanisms in the NiFe3O4/UHdA + PDS system were revealed via scavenging experiments and electron paramagnetic resonance analysis, which indicated a radical (•OH and SO4•−) as the major pathway and a nonradical (1O2) as the minor pathway for SMX degradation. Furthermore, NiFe3O4/UHdA exhibited fantastic magnetically separation and retained good catalytic activity with a low leached ion concentration during the performance of four cycles. Overall, the prepared NiFe3O4/UHdA with outstanding PDS activation could be a promising choice for the degradation of persistent organic pollutants from wastewater.

A retrospective study: analysis of the relationship between lactate dehydrogenase and castration-resistant prostate cancer based on restricted cubic spline model.

Different prostate cancer patients take different amounts of time to progress to castration-resistant prostate cancer (CRPC), and this difference in time determines the patient's ultimate survival time. If the time to progression to CRPC can be estimated for each patient, the treatment can be better individualized. Castration-resistant prostate cancer is a challenge in attacking prostate cancer, the aim of the paper is to analyze the correlation between lactate dehydrogenase (LDH) and CRPC occurrence based on the restricted cubic spline model, and to provide a theoretical basis for LDH as a prognostic biomarker for prostate cancer patients. We retrospectively analyzed clinical and follow-up data of patients diagnosed with prostate cancer and treated with Androgen Deprivation Therapy (ADT) in our hospital from October 2019 to August 2022. Investigate the correlation between LDH and CRPC by COX regression, restricted cubic spline model and survival analysis. The initial tPSA concentration, prostate volume, LDH and alkaline phosphatase levels in patients with prostate cancer with rapid progression are higher than those in patients with prostate cancer with slow progression. Multivariate COX regression showed that initial tPSA level and LDH level are independent risk factors for prostate cancer. Restricted cubic spline model further showed that LDH level is linearly correlated with the risk of CRPC in prostate cancer patients (total P<0.05, nonlinear P>0.05). LDH was associated with the prognosis of prostate cancer and had a dose-response relationship with the risk of CRPC in prostate caner patients.

Comparison of the Bioactive Properties of Human and Bovine Hemoglobin Hydrolysates Obtained by Enzymatic Hydrolysis: Antimicrobial and Antioxidant Potential of the Active Peptide α137-141.

This study focuses on the enzymatic hydrolysis of hemoglobin, the main component of cruor that gives blood its red color in mammals. The antibacterial and antioxidant potentials of human hemoglobin hydrolysates were evaluated in comparison to bovine hemoglobin. The results showed strong antimicrobial activity of the peptide hydrolysates against six bacterial strains, independent of the initial substrate concentration level. The hydrolysates also showed strong antioxidant activity, as measured by four different tests. In addition, the antimicrobial and antioxidant activities of the human and bovine hemoglobin hydrolysates showed little or no significant difference, with only the concentration level being the determining factor in their activity. The results of the mass spectrometry study showed the presence of a number of bioactive peptides, the majority of which have characteristics similar to those mentioned in the literature. New bioactive peptides were also identified in human hemoglobin, such as the antibacterial peptides PTTKTYFPHF (α37-46), FPTTKTYFPH (α36-45), TSKYR (α137-141), and STVLTSKYR (α133-141), as well as the antioxidant TSKYR (α137-141). According to these findings, human hemoglobin represents a promising source of bioactive peptides beneficial to the food or pharmaceutical industries.

Detergent Dissolution Intensification via Energy-Efficient Hydrodynamic Cavitation Reactors.

In this study, we explored the potential of hydrodynamic cavitation (HC) for use in dissolution of liquid and powder detergents. For this, microfluidic and polyether ether ketone (PEEK) tube HC reactors with different configurations were employed, and the results from the reactors were compared with a magnetic stirrer, as well as a tergotometer. According to our results PEEK tube HC reactors present the best performance for dissolution of liquid and powder detergents. In the case of liquid detergent, for the same level of initial concentration and comparable final dissolution, the PEEK tube consumed 16.7 and 70% of the energy and time of a tergotometer and 16.7 and 14.8% of that of a magnetic stirrer, respectively. In the case of powder detergent, the PEEK tube used 12% less power than a tergotometer and 81.2% less power than a magnetic stirrer. Additionally, the time required to dissolve the detergent was reduced significantly from 1200 s in the tergotometer and 1800 s in the magnetic stirrer to just 50 s in the PEEK tube. These results suggest that HC could significantly improve the dissolution rate of liquid and powder detergents and energy consumption in washing machines.

Insights on the isolation, identification, and degradation characteristics of three bacterial strains against mandipropamid and their application potential for polluted soil remediation

Bacteria-induced biodegradation techniques have become an effective approach for removing pesticide residues from polluted soils. However, their effect on chiral fungicides must be systematically evaluated and the efficiency and risk of each chiral enantiomer must be better understood. In this study, we isolated and enriched seven bacterial strains that are able to degrade mandipropamid from contaminated soil samples. Three bacterial strains with high degradation efficiency (63.6%–73.4%) were screened and identified as Pseudomonas sp. (M01), Mycolicibacterium parafortuitum (MW05), and Stenotrophomonas maltophilia (MW09) by morphological and 16S rRNA gene sequencing analyses. The degradation characteristics of three strains (M01, MW05, and MW09) was investigated and it was revealed that pH, temperature, and initial concentration of mandipropamid significantly impacted their degradation efficiency. The optimal conditions for degradation were a nutrient source of mandipropamid and an inoculation amount of 5%. We used a Box-Behnken model experiment and an analysis of variance to determine the most suitable conditions for degrading mandipropamid at various pH, temperature, and initial concentration levels. A response surface methodology analysis showed that the three strains had the highest mandipropamid degradation efficiency (> 96%) under various conditions (pH: 7.15–7.71, temperature: 28.61–30.76 °C, initial concentration: 5.524–5.934 mg/L). Mycelial, intracellular, and extracellular enzymes also had an impact on the degradation of mandipropamid enantiomers by the three strains. In soil remediation trials, the three bacterial strains could effectively enantioselectively degrade rac-mandipropamid residues in polluted sterilized and natural soil samples (R-enantiomer was degraded faster) and influence the activity of urease and β-glucosidase in the soil. The results revealed several candidate bacterial strains for mandipropamid biodegradation and provide information on mandipropamid biological detoxification in soil environments.

Insulin Signaling Pathway Model in Adipocyte Cells.

Worldwide, type 2 diabetes mellitus (T2DM) is one of the most pervasive and fast-growing disorders, bringing long-term adverse effects. T2DM arises from pancreatic β-cells deficiency to produce enough insulin or when the body cannot effectively use the insulin produced by such cells. Accordingly, early diagnosis will decrease the long-term effects and high-healthcare costs of diabetes. The objective is developing an integrated mathematical model of the insulin signaling network based on Brännmark's model, which can simulate the signaling events more comprehensively with the added key components. In this study, a thorough mathematical model of the insulin signaling network was developed by expanding the previously validated model and incorporating the glycogen synthesis module. Parameters (69 parameters) of the integrated model were evaluated by a genetic algorithm by fitting the model predictions to eighty percent of experimental data from the literature. Twenty percent of the experimental data were used to evaluate the final optimized model. The time-response curves indicate that the GS phosphorylation reaches its maximum in response to 10-7 M insulin after 4 min, while the maximum phosphorylated GSK3 is attained within ~50 min. The dose-response curves for the GSP and GSK3 of the insulin signaling intermediaries in response to the increased concentration of insulin, after 10 min, in the input from 0-100 nM exhibits a decreasing trend, whereas an increasing trend was observed for the GS and GSK3P. The GSK and GS phosphorylation sensitivity was enhanced by increasing the initial insulin concentration level from 0.001 to 100 nM. However, the sensitivity of GSK3 to insulin concentration changes (from 0.001 to 100 nM) was 3-fold higher than GS sensitivity. Considerably, the trends of all signaling components simulated by the expanded model shows high compatibility with experimental data (R2 ≥ 0.9), which approves the accuracy of the proposed model. The proposed mathematical model can be used in many biological systems and combined with the whole-body model of the blood glucose regulation system for a better understanding of the causes and potential treatment of type 2 diabetes. Although, this model is not a complete description of insulin signaling, yet it can make profound contributions to improvements regarding other important components and signaling branches such as epidermal growth factor (EGF) signaling, as well as signaling in other cell types in the model structure of future works.

Quantitative microbiological risk assessment of traditional food of animal origin produced in short supply chains in Poland.

Polish raw-milk cheeses produced in short supply chains may pose a threat to consumer safety due to pathogen presence. Listeria monocytogenes is a bacterium of great importance for the food safety of refrigerated RTE foods due to its ability to grow at refrigeration temperatures. During the EU-FORA fellowship, a stochastic risk assessment was designed and executed to estimate the risk for consumers from L. monocytogenes in these products. The aim was to develop a probabilistic QMRA model that would incorporate the variability and uncertainty of the model's inputs such as prevalence, initial concentration levels, product intrinsic factors, domestic storage temperature and consumer behaviour. The project involved data collection and analysis, growth model selection, mathematical modelling and Monte Carlo analysis in R programming language. Microbiological and physicochemical testing were carried out throughout the year on two types of cheeses in combination with a domestic refrigerator temperature survey and accompanying consumption questionnaire. Collected data were fitted to probability distributions using R. The appropriate growth model for the pathogen was selected based on an inoculation study performed on one of the raw-milk cheeses and the chosen mathematical model was written into the R script developed for the QMRA. The dose-response model used the ingested dose calculated from the modelled concentration of L. monocytogenes at the time of consumption and the single serving size from the questionnaire to estimate the probability of illness. The final risk was expressed as probability of listeriosis for Polish consumers per serving of raw-milk cheese.

The effect of substrate consumption on the increasing of biofloculans productivity and activity of cultivation by Alcaligenes latus

The efficient technology cultivation is developed as a respond to the emergence of clean technology trend issue to produce biogically degraded product. This research aims to review the effect of sweet potato hydrolysis concentration on biofloculan cultivation productivity and its effect on flocculation activity. Cultivation starts from cell refreshment to propagation and inoculation into cultivation medium which has been sterilized. Enzymatically, the sweet potato starch hydrolyzate supernatant usage (S) as a cultivation medium is expected can substitute glucose (G) synthetic medium and able to increase bioflocculant activity and bioabsorbent formation, while the Nitrogen substrate usage from CSL (C) and yeast extract (Y) into the medium. Cultivation of Alcaligenes latus can stimulate the formation of acid biopolymers which have large molecular weights. Furthermore, made a notation like SC-10 which is a medium of glucose supernatant factor with Corn steep liquor (CSL) with an initial sugar concentration level of 10 g/l. Control process including the analysis of reduced sugar (RS) and nitrogen, viscosity, pH, measurement of dry cell weight (DC), and flocculation activity (AF) is conducted during cultivation. The research results indicates the usage of sweet potato supernatan hydrolysate is to subsitute the synthetic mediums due to its ability to increase biofloculan activity. The best medium for biofloculan cultivation is SC-10 with kinetic parameter μ, 0,0834 hours-1; Xmax,12,54 g/l; m, 0,641 and n, 0,0105 g product/g biomass/hours; α, 0,409 and β, 0,0006 g biomass/g substrate/ hours; Yp/s, 68%; Yx/s, 97%. There is no significant viscosity changes during cultivation so that it can not be used as a production index. Flocculation Activity resulting from the cultivation of SC-10 medium is the strongest process in forming flok-flok while SC-30 medium is the least.

Adsorption of cadmium (Cd) and lead (Pb) using powdered activated carbon derived from Cocos Nucifera waste: A kinetics and equilibrium study for long-term sustainability

In this research, the activated carbon was prepared using burnt Coconut (Cocos Nucifera) shell and was used as an adsorbent in the removal of toxic heavy metal ions of lead (Pb) and cadmium (Cd) from the aqueous solution using batch adsorption study. Cocos Nucifera was initially collected in the forming shell and then it was crushed in the form of granular. The carbon shell's surface has been modified with an oxidizing agent such as sulphuric acid or nitric acid to increase the shell's adsorption capacity. The effect contact time, pH, temperature, initial concentration, and adsorbent dosage level were analyzed. The result shows that the optimum pH was 6, and the capacity of adsorption was affected by the temperature. The efficiency of the adsorption rises with an increment in temperature. In addition, the characteristics of the adsorbents were studied by making use of SEM, FT-IR, and Energy Dispersive X-ray Analysis (EDX). The adsorption isotherm study was carried out using Langmuir and Freundlich isotherm model, and it shows the charcoal/carbon shell adsorption followed the Langmuir isotherm model. The modeling result of the kinetic model study indicates that the adsorption mechanism of lead (Pb) and cadmium (Cd) process of adsorption were fitted with a pseudo-second-order equation.

Bariatric Surgery Induced Changes in Blood Cholesterol Are Modulated by Vitamin D Status.

The effect of metabolically active bariatric surgery treatment on lipid metabolism is inconclusive. The authors of this study presume that initial vitamin D status may play a regulating role in influencing the beneficial post-effects of bariatric surgery, especially the lipid profile. The biochemical data obtained from 24 patients who had undergone laparoscopic one-anastomosis gastric bypass (OAGB) at baseline, 3 months before the surgery, at the time of surgery, and 6 months later, demonstrate that vitamin D status influenced the postoperative lipid profile. The baseline established the partition line which divided patients into two groups according to the stated calcidiol initial concentration level of 32 ng/mL. The data shows that OAGB induces a decrease in TG and hsCRP while increasing HDL. Conversely, in patients whose 25(OH)D3 was below 32 ng/mL TC significantly increased while those above this concentration remained in the normal physiological range. The changes induced by OAGB in TG, glucose, and hsCRP were similar in both groups. Unexpectedly, the surgery did not affect vitamin D metabolites. In conclusion, the results of the study suggest that a higher concentration of serum 25(OH)D3 may enhance the protective effects of OAGB.

Effectiveness of Non-Thermal Plasma Induced Degradation of Per- and Polyfluoroalkyl Substances from Water

Per- and polyfluoroalkyl substances (PFAS) are omnipresent synthetic chemicals. Due to their industrial importance and widespread use as a key component in various applications and a variety of products, these compounds can be found today in high concentrations (&gt;1 μg/L) in surface and groundwater but also spread throughout the ecosystem, where they represent a serious threat to most living organisms. The removal or degradation of PFAS contaminants from water and soil is becoming a legal obligation in a growing number of countries around the globe. This, however, demands novel techniques for the degradation of PFAS since conventional water treatment techniques are either insufficient or extremely expensive due to the persistent nature of these compounds caused by their extraordinary chemical stability. The goal of this work was therefore to investigate the practical potential of the application-oriented use of atmospheric non-thermal plasma as a powerful advanced oxidation method for the purification of water contaminated with PFAS compounds. Special attention was devoted to the development of the concept that can be scaled up to the capacity level of approximately 100–200 m3 of water per hour, contaminated with PFAS and other contaminants including organic and inorganic material generally present in soil, and surface or groundwater. Our major research interest was to define the minimum required treatment time for optimal purification results, as well as to understand the influence of the initial concentration of PFAS in water and the potential presence of co-contaminants often present in situ on the efficiency of the degradation process. A chemical analysis of the treated samples demonstrated the ability of the atmospheric plasma to reduce more than 50% of the initial PFAS amount in the water samples in less than 300 s of treatment time. PFOA, however, showed more rigidity towards degradation, where a double treatment time was needed to reach similar degradation levels. The obtained results showed that the initial concentration level does not play a major role in the process. However, the PFAS degradation profiles for all tested concentrations show a strongly nonlinear behavior with time, characterized by the fast decrease of the process efficiency in the case of longer treatment times. For prolonged treatment times, a constant increase in the samples’ conductivity was measured, which might be the limiting factor for the degradation rate in the case of prolonged treatment times.

Innovation concentration in knowledge network.

This paper studies the increase in innovation concentration levels of U.S. industries over the last two decades. I present a model of imperfectly competitive patent market with heterogeneous firms that generate endogenous variable markups. Theoretically and empirically, the price of a firm’s newly invented knowledge, the profit and survival rate of the innovating firm depends on the market share of this firm’s knowledge stock and the position of industry in the knowledge network. In the process of innovating, firm pays a random fixed cost in each period which together with market share largely determines its decision on whether to innovate into different sectors. I find that firms with larger market share not only invest more in R&D but also enter into more sectors. Since innovating firms could create blueprints for new varieties and manufacture the products that have been invented, I bridge the gap between the product and the R&D markets to document the similar concentration trends between them. I prove that large firms in the product market would charge higher price on their product so that they can charge higher profit which is a part of the value of their knowledge. Lastly, the increasing trend of concentration could decrease consumers’ welfare in the industries with high initial concentration levels.

Assessment of substrate load and process pH for bioethanol production – Development of a kinetic model

In the present work, four levels of initial substrate concentration (2%, 4%, 7%, and 10% w/v glucose), and six pH values (4.0, 4.5, 5.0, 5.5, 6.0, and 6.5) at 2% substrate load were used to assess their impact on bioethanol production from Saccharomyces cerevisiae, in order to develop a kinetic model. A synthetic medium, containing glucose as the only carbon and energy source was used as the fermentation substrate. An innovative kinetic model was developed to fit the obtained data since several bioethanol production inhibition models reported in literature failed to sufficiently describe the experimental results. To this end, the logistic model was used to express the inhibition of biomass growth and the Monod model to describe the limitation of growth due to substrate depletion. In addition, Smax was imported as the parameter that affects the yield of ethanol production rate to biomass growth rate (Ye/x), as a function of substrate concentration. Two more parameters were used to describe substrate (glucose) consumption for maintenance purposes (Kcm) and simultaneous bioethanol production (Ycm) during the biomass stationary phase, where bioethanol is still being produced. The proposed model showed a high coefficient of correlation, R2 = 0.9694. Both the yeast growth and bioethanol production were not substantially affected by the pH, within the range of pH values tested in this study.

Biodegradation Kinetics of Fragrances, Plasticizers, UV Filters, and PAHs in a Mixture─Changing Test Concentrations over 5 Orders of Magnitude.

Biodegradation of organic chemicals emitted to the environment is carried out by mixed microbial communities growing on multiple natural and xenobiotic substrates at low concentrations. This study aims to (1) perform simulation type biodegradation tests at a wide range of mixture concentrations, (2) determine the concentration effect on the biodegradation kinetics of individual chemicals, and (3) link the mixture concentration and degradation to microbial community dynamics. Two hundred ninety-four parallel test systems were prepared using wastewater treatment plant effluent as inoculum and passive dosing to add a mixture of 19 chemicals at 6 initial concentration levels (ng/L to mg/L). After 1-30 days of incubation at 12 °C, abiotic and biotic test systems were analyzed using arrow solid phase microextraction and GC-MS/MS. Biodegradation kinetics at the highest test concentrations were delayed for several test substances but enhanced for the reference chemical naphthalene. Test concentration thus shifted the order in which chemicals were degraded. 16S rRNA gene amplicon sequencing indicated that the highest test concentration (17 mg C/L added) supported the growth of the genera Acidovorax, Novosphingobium, and Hydrogenophaga, whereas no such effect was observed at lower concentrations. The chemical and microbial results confirm that too high mixture concentrations should be avoided when aiming at determining environmentally relevant biodegradation data.

Photo-oxidation of three major pharmaceuticals in urban wastewater under artificial and solar irradiations

The conditions of wastewater treatment by photo-oxidation are addressed in this work with the aim of highlighting the importance of the matrix, concentration and cocktail effects of pharmaceutical pollutants very present in wastewater treatment plant. The idea is to operate under real conditions, i.e. effluent from the WWTP, representative concentrations and natural irradiation. Photospheres are micrometric glass spheres coated with TiO2 which have the particularity to float and therefore be much easier to separate from treated water during photocatalysis. Three pharmaceutical target molecules were chosen: carbamazepine (CBZ), diclofenac (DCF) and ibuprofen (IBU) to evaluate, in a controlled 2 L artificial UV photoreactor, the individual and coupled effects of three strategic points: i) the matrix effect (tap water vs filtered treated wastewater), ii) the cocktail effect (one molecule vs the three mixed together) and iii) the initial concentration level effect (µg/L vs mg/L). A 300 L solar photoreactor was also designed for this study to evaluate the transferability of performances. Experiments conducted under controlled conditions highlighted that i) the molecule removal was most negatively impacted by the matrix effect, ii) the cocktail effect, even if still negative, appeared to decrease the difference between the degradation rates and iii) initial low concentrations were easier to degrade than higher laboratory concentrations. Transposition to the larger scale solar photoreactor confirmed the order of molecule degradation: DCF > IBU > DCF when alone and DCF > CBZ > IBU when mixed together but also showed that this set up was actually more efficient in the degradation of these molecules than the artificial photoreactor.

Adsorption Features of Loess Calcareous Nodules to Heavy-Metal Ions in Aqueous Solution

This paper explores the use of calcareous tuberculosis as an adsorbent and heavy-metal ions (Cu2+, Zn2+, Cd2+, and Pb2+) as adsorbates, and the influence of varying levels of particle size, adsorption time, pH, adsorbent dosage, and initial concentration of heavy metals is studied through an experiment of single heavy-metal adsorption. In addition, the impact of the temperature and other factors on the adsorption of heavy-metal ions by calcareous nodules is analyzed to identify the optimal conditions for the adsorption of heavy-metal ions by calcareous nodules. As shown by the research findings, the adsorption rates of Cu2+, Zn2+, and Pb2+ gradually declined with the increase in particle size, with no evident effect on Cd2+. In the meantime, with further increases in factors such as the adsorption time, adsorbent dosage, and temperature, the adsorption rates of Cu2+, Zn2+, Cd2+, and Pb2+ experienced gradual increases. The adsorption rates of Cu2+, Zn2+, and Cd2+ gradually declined with the increase in initial concentration of heavy-metal ions, whereas the adsorption rate of Pb2+ experience increased first and then declined. As the pH increased, the adsorption rate of Cd2+ experience increased first and then declined at a slow pace. The adsorption rates of Cu2+, Zn2+, and Pb2+ increased first and then decreased. The adsorption capacity of calcareous nodules toward the four heavy-metal ions was in the order of Pb2+ &gt; Zn2+ &gt; Cu2+ &gt; Cd2+. When the particle size was set to 0.25 mm, the adsorption time was set to 120 min, and the dosage was set to 0.6 g, the calcareous nodules included Pb2+, Zn2+, and Cu2+. Moreover, Cd2+ was able to achieve stronger adsorption capacity, with the adsorption rate able to reach 83.33%, 77.78%, 73.81%, and 81.93% of its maximum level. Therefore, as the particle size of the heavy-metal ions decreased, the adsorption capacity generally became stronger. As the adsorption time increased, the temperature and the amount of adsorbent also increased. The optimal pH value for the adsorption of calcareous nodules toward Pb2+, Zn2+, Cu2+, and Cd2+ was found to be 7, 6, 5, and 8, respectively, and the optimal temperature was 50 °C. In summary, calcareous nodules are a natural, low-cost, and effective adsorbent.