In the context of urban agriculture, where soils are frequently contaminated with metal(loid)s (TM), we studied the influence of vermicompost amendments on symbiotic fungal communities associated with plants grown in two metal-rich soils. Leek (Allium porrum L.) plants were grown with or without vermicompost in two metal-rich soils characterized by either geogenic or anthropogenic TM sources, to assess the influence of pollutant origin on soil-plant transfer. Fungal communities associated with the leek roots were identified by high throughput Illumina MiSeq and TM contents were measured using mass spectrometry. Vermicompost addition led to a dramatic change in the fungal community with a loss of diversity in the two tested soils. This effect could partially explain the changes in metal transfer at the soil-AMF-plant interface. Our results suggest being careful while using composts when growing edibles in contaminated soils. More generally, this study highlights the need for further research in the field of fungal communities to refine practical recommendations to gardeners.
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Silver nanoparticles (Ag NPs) were synthesised by the reduction of Ag+ to Ag0 in the presence of enol form of flavonoids present in plant extract of Tabernaemontana divaricate (T. divaricate). Prepared Ag NPs were characterised using UV–Vis, XRD, HR-TEM with EDX and XPS techniques. XPS spectra exhibited peaks at 366 eV and 373 eV, which specified spin orbits for Ag 3d3/2, and Ag 3d5/2 that confirmed the formation of Ag NPs. Ag NPs were spherical in shape with an average size of 30 nm as revealed by HR-TEM and FE-SEM techniques. EDX studies verified the high purity of Ag NPs with silver 46.96%, carbon 16.35%, oxygen 16.22%, nitrogen 20.25% and sulphur 0.21%. LC–MS analysis of plant extract confirmed the qualitative presence of alkaloids, tannins, flavonoids, phenols, and carbohydrates. Prepared Ag NPs showed good photocatalytic activity towards degradation of 4-Amniopyridine with 61% degradation efficiency at optimum conditions in 2 h of reaction time under visible light. The ten intermediates were found within the mass number of 0–450. Ag NPs synthesised using bio-extract have also shown good inactivation against Escherichia coli (E. coli) and Bacillus subtilis (B. subtilis) bacteria due to the availability of free radicals.
Graphical abstractEchinacea purpurea (L.) Moench was selected as a remediation plant in this study, and different concentrations of graphene oxide (GO) were added to Cd-contaminated soil. Through pot experiments, the effect of E. purpurea on Cd-contaminated soil was determined at 60 days, 120 days, and 150 days. A preliminary study on the remediation mechanism of GO was explored through changes in the forms of Cd in the rhizosphere soil, soil pH, and soil functional groups. Results showed that the optimal concentration of GO was 0.4 g/kg, and under the condition, the accumulation of Cd in the roots of E. purpurea was as high as 113.69 ± 23.86 mg/kg, and the maximum EF reached 5.87 ± 1.34. Compared with those of the control group, accumulated Cd concentration and EF in the roots increased by 60.34% and 2.32, respectively. Correlation analysis showed that the absorption and accumulation of Cd was negatively correlated with the exchangeable Cd content at 120 days, and the exchangeable Cd was negatively correlated with the relative content of functional groups in the soil with 0.4 g/kg GO (E2). The artificial application of GO to the soil can be used as an effective way to improve the effect of E. purpurea in the remediation of Cd soil pollution, and it has great application potential in the stabilization of plants and vegetations and restoration of high-concentration Cd-contaminated soil.
Graphical abstractThe changes in some potentially toxic elements (PTEs) including lead (Pb), cadmium (Cd), arsenic (As), iron (Fe), zinc (Zn), and copper (Cu) during pekmez (grape molasses-like syrup) processing and the utilization of various types of clarifiers (white soil, bentonite, and gelatin) in two levels (1.5 and 3% w/w) were analyzed. The average concentrations of Pb, Cd, As, Fe, Zn, and Cu in grape samples were measured as 0.055?±?0.005, 0.030?±?0.002, 0.044?±?0.002, 2.882?±?0.013, 2.372?±?0.088, and 1.194?±?0.01 μg g?1. During pekmez production, the range of changes in Pb, Cd, As, Fe, Zn, and Cu was ?43.38% to 40.25%, ?55.49% to 0.23%, ?76.15% to 1.80%, ?74.15% to 58.47%, ?40.55% to ?18.12%, and ?83.16% to ?21.39%, respectively. The effect of the clarification process on the PTEs depended on the type and concentration of both PTE and clarifier agent used while the incorporation of gelatin resulted in a significant reduction in all of PT.
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Dissolved humic substances (DHSs) are the major components of organic matter in the aquatic environment. DHSs are well known to considerably affect the speciation, solubility, and toxicity of a wide variety of pollutants in the aquatic environment. In this study, the effects of the toxicity of heavy metals and hydrophobic organic pollutants (HOPs) on Chlamydomonas reinhardtii in the presence of humic acid (HA) were examined by a microscale algal growth inhibition (μ-AGI) test based on spectrophotometric detection. To clarify the relationship between the chemical properties of HAs and the toxicity change of pollutants, eight HAs from different sources were prepared and used. HAs were responsible for mitigating the toxicity of Hg, Cu, pesticides (γ-HCH, 2,4-D, and DDT), and polycyclic aromatic hydrocarbons (PAHs) such as naphthalene (Nap), anthracene (Ant), and benzo[a]pyrene (BaP). In particular, an approximately 100-fold decrease in the toxicity of BaP was observed in the presence of 10 ppm HAs extracted from tropical peat. The results indicated that the carboxylic group content and the HA molecular weight are correlated to the changes in the heavy metal toxicity. For HOPs, the aromaticity and polarity of HAs are crucial for mitigating their toxicity. Furthermore, it was clearly shown that the lake water including a high concentration of DHSs collected from Central Kalimantan, Indonesia, reduced the toxicity of Hg and γ-HCH on Chlamydomonas reinhardtii.
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Acetaminophen (ACT) is one of the most frequently detected pharmaceuticals in aqueous environments, and treatment of ACT were generally carried out by photocatalytic degradations under high energy UV irradiation. In this study, potassium ferricyanide was utilized as a quadruple-elemental dopant in a TiO2 photocatalyst in order to enhance its visible-light activity. Two critical parameters (amounts of dopants and durations of calcination) of the synthesis of the photocatalyst by a sol–gel method were systematically evaluated. Crystal structure of the doping TiO2 was examined by X-ray diffraction while the effects of the two parameters on the photocatalytic activity were elucidated by various characterizations. Increasing the amount of dopant or the duration of calcination red-shifted the UV–vis DRS of the doped TiO2. The estimated band gap energy of the doped TiO2 decreased slightly as the amount of dopant increased, but it increased as the duration of calcination increased. The FT-IR yielded characteristic peaks that revealed the effects of the two parameters, whereas the SEM images revealed the morphological evolutions of each effect. The photocatalyst, synthesized at optimum conditions was able to remove 99.1 % acetaminophen with rate constant of 7.9 × 10−3 min−1, which was 4.88 times greater than virgin TiO2. In general, this study not only optimized synthetic conditions of the new visible-light active photocatalyst for ACT degradation but also presented characterizations conducted by SEM, XRD, UV–vis DRS, and FTIR to elucidate the relationship between modified structure and the photocatalytic activity.
Effects of doping amounts of K3[Fe(CN)6] and calcunation duration on visible light absorbance of TiO2 photocatalysts
The buoyancy of Microcystis colonies determines the occurrence and dominance of bloom on the water surface. Besides the cell density regulation and the formation of larger size aggregates, increases in cell volume per colony (Vcell) and the colony’s compactness (i.e., volume ratio of cells to the colony, VR) may promote Microcystis colony buoyancy. Yet only a few studies have studied the relationship between the internal structure variation of colonies and their buoyancy, and the co-regulatory role of Vcell and VR of Microcystis colonies in the floating velocity (FV) remains largely unexplored. In the present study, we optimized a method for measuring the compactness of Microcystis colonies based on the linear relationship between total Vcell and chlorophyll a. Different relationships between the VRs and FVs were observed with different colony size and Vcell range groups. Both field and laboratory experiments showed that FV/(D50, median diameter)2 had a significant linear relationship with VR, indicating that the cell density and extracellular polysaccharides were unchanged over a short time period and could be estimated via the slope and intercept of a fitted line. We also constructed a functional relationship between FV, VR, and Vcell and found that high VR and Vcell can promote Microcystis buoyancy. This means that increasing cell compactness or Vcell may be an active regulation strategy for Microcystis colonies to promote buoyancy. Therefore, quantifying the internal structure of Microcystis colonies is strongly recommended for the assessment of Microcystis bloom development and their management.
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This study assessed the concentration, bioconcentration, and bioaccumulation of As, Cd, Co, Cr, Cu, Mg, Mn, Ni, Pb, and Zn in juvenile fishes (Acestrorynchus pantaneiro, Brycon orbygnianus, Cyphocharax voga, Megaleporinus obtusidens, Odontesthes bonariensis, Pimelodus maculatus, Prochilodus lineatus, Salminus brasiliensis, and Schizodon borelli) in the Lower Paraná River (Argentina), the most extensive floodplain from the Plata Basin. The floodplain is crucial for the reproduction and growth of various species such as P. lineatus, M. obtusidens, and S. brasiliensis, which complete their life cycle in this environment. In total, 90 individuals were sampled for nitrogen stable isotope, and trace element analysis in muscle tissue, water, and sediment was analyzed. The results show that all the studied species bioaccumulate Cr, Mg, Ni, and Zn. In particular, B. orbygnianus and P. maculatus presented the highest bioaccumulation factor for Cr. A biodilution of Co through the food chain was observed. No positive correlation was found between element concentration and trophic level, but we observed significant differences between trophic guilds (herbivorous, omnivorous, and carnivorous). Our findings suggest that feeding habits determine trace element concentrations. To establish differential behavior between different species within the aquatic web further studies are necessary, particularly in the floodplain of the Paraná, which is a crucial nursery area for most commercially important fishes from the Plata Basin.
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Electrocoagulation (EC) is an excellent and promising technology in wastewater treatment, as it combines the benefits of coagulation, flotation, and electrochemistry. During the last decade, extensive researches have focused on removal of emerging contaminants by using electrocoagualtion, due to its several advantages like compactness, cost-effectiveness, efficiency, low sludge production, and eco-friendness. Emerging contaminants (ECs) are micropollutants found in trace amounts that discharging into conventional wastewater treatment (WWT) plants entering surface waters and imposing a high threat to human and aquatic life. Various studies reveal that about 90% of emerging contaminants are disposed unscientifically into water bodies, creating problems to public health and environment. The studies on removal of emerging contaminants from wastewater are by global researchers are critically reviewed. The core findings proved that still more research required into optimization of parameters, system design, and economic feasibility to explore the potential of EC combined systems. This review has introduced an innovative collection of current knowledge on electro-coagulation for the removal of emerging contaminants.
Graphical abstractIt has been known since the 1970s that differences exist in the profile of element content in wild-growing mushroom species, although knowledge of the role of mushroom species/families as determinants in the accumulation of diverse element remains limited. The aim of this study was to determine the content of 63 mineral elements, divided into six separate groups in the fruit bodies of 17 wild-growing mushroom species. The mushrooms, growing in widely ranging types of soil composition, were collected in Poland in 2018. Lepista nuda and Paralepista gilva contained not only the highest content of essential major (531 and 14,800 mg kg−1, respectively of Ca and P) and trace elements (425 and 66.3 mg kg−1, respectively of Fe and B) but also a high content of trace elements with a detrimental health effect (1.39 and 7.29 mg kg−1, respectively of Tl and Ba). A high content of several elements (Al, B, Ba, Bi, Ca, Er, Fe, Mg, Mo, P, Sc, Ti or V) in L. nuda, Lepista personata, P. gilva and/or Tricholoma equestre fruit bodies belonging to the Tricholomataceae family suggests that such species may be characterised by the most effective accumulation of selected major or trace elements. On the other hand, mushrooms belonging to the Agaricaceae family (Agaricus arvensis, Coprinus comatus and Macrolepiota procera) were characterised by significant differences in the content of all determined elements jointly, which suggests that a higher content of one or several elements is mushroom species-dependent.
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Ecological assessment of freshwater ecosystems based on diatom metrics is an important issue for attaining environmental sustainability. The present study aimed to evaluate differences in the diatom–stressor relationship in relatively least disturbed streams in the Konya closed river basin using multivariate analyses and to bio-assess streams by the application of different ecoregional diatom indices. Cocconeis euglypta, Cymbella excisa, Cocconeis placentula, and Achnanthidium minutissimum are the most contributing species to the dissimilarity of sampling stations between rainy (spring) and dry (summer and fall) seasons and also between altitude (A2 800- < 1600 m and A3 ≥ 1600 m) groups. The first two axes of canonical correspondence analysis revealed a significant (82.8%) relationship between diatom species and stressors. Diatom species displayed distinct responses to environmental variables (electrical conductivity, Ni, Cu, B, and altitude) playing important roles on the distribution of species. Diatom indices indicate different ecological statuses of stations, from bad to high. European diatom indices except Duero Diatom Index (DDI) and Trophic Diatom Index (TDI) showed good responses to the eco-assessment of streams and indicated high ecological status for the least disturbed sampling stations symbolized as S16, S20, S24, S25, S27-29, S37, and S39. These results were also supported by abiotic evaluation. Although TIT was more competitive in the bio-assessment of streams among diatom indices, it is necessary to increase its species list by determining their trophic weights in future studies. Therefore, the use of ecoregion-specific diatom indices is suggested along with increasing the number of used species to correctly interpret the water quality.
Graphical AbstractAtmospheric contamination by heavy metal(loid)–enriched particulate matter (metal-PM) is highly topical these days because of its high persistence, toxic nature, and health risks. Globally, foliar uptake of metal(loid)s occurs for vegetables/crops grown in the vicinity of industrial or urban areas with a metal-PM-contaminated atmosphere. The current study evaluated the foliar uptake of arsenic (As), accumulation of As in different plant organs, its toxicity (in terms of ROS generation, chlorophyll degradation, and lipid peroxidation), and its defensive mechanism (antioxidant enzymes) in spinach (Spinacia oleracea) after foliar application of As in the form of nanoparticles (As-NPs). The As-NPs were prepared using a chemical method. Results indicate that spinach can absorb As via foliar pathways (0.50 to 0.73 mg/kg in leaves) and can translocate it towards root tissues (0.35 to 0.68 mg/kg). However, health risk assessment parameters showed that the As level in the edible parts of spinach was below the critical limit (hazard quotient <?1). Despite low tissue level, As-NP exposure caused phytotoxicity in terms of a decrease in plant dry biomass (up to 84%) and pigment contents (up to 38%). Furthermore, several-fold higher activities of antioxidant enzymes were observed under metal stress than control. However, no significant variation was observed in the level of hydrogen peroxide (H2O2), which can be its possible transformation to other forms of reactive oxygen species (ROS). It is proposed that As can be absorbed by spinach via foliar pathway and then disturbs the plant metabolism. Therefore, air quality needs to be considered and monitored continuously for the human health risk assessment and quality of vegetables cultivated on polluted soils (roadside and industrial vicinity).
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Activated carbon was one of the main adsorptions utilized in elemental mercury (Hg0) removal from coal combustion flue gas. However, the high cost and low physical adsorption efficiency of activated carbon injection (ACI) limited its application. In this study, an ultra-high efficiency (nearly 100%) catalyst sorbent-Sex/Activated carbon (Sex/AC) was synthesized and applied to remove Hg0 in the simulated flue gas, which exhibited 120 times outstanding adsorption performance versus the conventional activated carbon. The Sex/AC reached 17.98 mg/g Hg0 adsorption capacity at 160 °C under the pure nitrogen atmosphere. Moreover, it maintained an excellent mercury adsorption tolerance, reaching the efficiency of Hg0 removal above 85% at the NO and SO2 conditions in a bench-scale fixed-bed reactor. Characterized by the multiple methods, including BET, XRD, XPS, kinetic and thermodynamic analysis, and the DFT calculation, we demonstrated that the ultrahigh mercury removal performance originated from the activated Se species in Sex/AC. Chemical adsorption plays a dominant role in Hg0 removal: Selenium anchored on the surface of AC would capture Hg0 in the flue gas to form an extremely stable substance-HgSe, avoiding subsequent Hg0 released. Additionally, the oxygen-containing functional groups in AC and the higher BET areas promote the conversion of Hg0 to HgO. This work provided a novel and highly efficient carbon-based sorbent -Sex/AC to capture the mercury in coal combustion flue gas.
Selenium-modified porous activated carbon and the interface functional group promotes the synergistic effect of physical adsorption and chemical adsorption to promote the adsorption capacity of Hg0.
Diet is an important exposure route for phthalates, such as di-iso-butyl phthalate (DiBP), dibutyl phthalate (DBP), bis(2-ethylhexyl) phthalate (DEHP), and benzyl butyl phthalate (BBP). In this study, we aimed to estimate phthalate exposure in the diet of pregnant women and assess the health risk. A total of 517 pregnant women in the first trimester were recruited, and food frequency questionnaires were collected. A simple distribution assessment method was used to estimate daily exposure, and the hazard index (HI) method was used to assess cumulative risk. The maximum daily dietary exposure to DEHP, DBP, DiBP, and BBP was 5.25, 3.17, 2.59, and 0.58 μg/kg bw/day, respectively, and did not exceed the safety limit values. Cereals and vegetables were the main sources of the estimated daily intake (EDI) of phthalates in the diet. The cumulative risk assessment, based on the European Food Safety Authority tolerable daily intake (TDI) and the US Environmental Protection Agency reference dose (RfD), did not exceed the threshold of 1. DiBP, DBP, and DEHP had higher hazard quotient (HQ) values for cumulative health risk than BBP. In conclusion, a low health risk was posed by the cumulative dietary exposure to phthalates for pregnant women in Beijing.
Graphical abstractDrinking water reservoirs are threatened globally by anthropogenic nitrogen pollution. Hydrochemistry and isotopes were analyzed to identify spatial and temporal varieties of main nitrate sources in a large drinking water reservoir in East China. The results showed that NO3? was the main nitrogen form in both the dry and wet seasons, but dissolved organic nitrogen (DON) was increased in the wet season. The δ15N-NO3? values (+?1.3‰ to +?11.8‰) and δ18O-NO3? values (+?2.5‰ to +?13.5‰), combined with principal component analysis (PCA), indicated that chemical fertilizer was the main nitrate source during the dry season, while chemical fertilizer, soil N, and sewage/manure were the main nitrate sources during the wet season in the Qiandao Lake area. And, the nitrate isotopes showed the significant nitrification and assimilation in the Qiandao Lake area. A Bayesian isotopic mixing model (Stable Isotope Analysis in R) was applied to the spatial and seasonal trends in the proportional contribution of four NO3? sources (chemical fertilizer (CF), soil nitrogen (SN), sewage and manure (SM), and atmospheric deposition (AD)) in the Qiandao Lake area. It was revealed that CF was the most important nitrate source in the dry season, accounting for 53.4% with 19.2% of SM and 18.9% of SN, while the contribution of SN increased in the wet season, accounting for 31.6%, followed by CF (30.8%) and then SM (24.2%). The main nitrate sources in the urban area, rural area, and central lake area were CF and SN, accounting for 66.1% in the urban area, 71.7% in the rural area, and 68.2% in the central lake area. Measures should be made to improve chemical fertilizer use efficiency and to reduce nitrogen loss in the Qiandao Lake area.
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Agriculture is the main occupation of the majority of people in India. The majority of the population in India is dependent (directly or indirectly) on agriculture as an occupation. The agriculture sector requires more freshwater and power for better yield in the current scenario. Nevertheless, the ever-increasing rate of energy consumption, limited fossil fuels, and rising pollution have made the expansion of renewable resources essential. Due to the suitable solar potential available in India, the deployment of solar energy has been more as compared to other renewable resources. The current study aims to discuss the various technologies, initiatives and policies of solar energy usage in agriculture. This work delivers an assessment of the advancement of solar energy vis-à-vis agricultural applications through the greenhouse concept and photovoltaic approach in India. Various agricultural applications of solar energy, such as solar water desalination system, solar water pumping system, solar crop dryer system for food safety, etc. are discussed as a means to promote solar-based technology. It also highlights the scenario of solar energy in India with important accomplishments, developmental approaches, and future potential. In-depth studies of various policies and government initiatives including those in research and development are also discussed. The current survey on solar technologies will be an aid to agribusiness frameworks to comprehend the statuses, obstructions, and extent of advancement. Finally, some future recommendations for further developments in this approach are discussed. This work sheds light on varied areas of solar energy-assisted agricultural systems as a potentially sustainable and eco-friendly pathway.
Graphical abstractLianhuaqingwen (LH), one traditional Chinese medicine (TCM), has been used to treat the coronavirus disease 2019 (COVID-19), but its ecotoxicity with potential human health security has not been well investigated. To overcome such adverse effects and improve its medication efficacy, an intelligent multi-method integrated dietary scheme, screening, and performance evaluation approach was developed. Thirteen LH compounds were selected, and the main protease (Mpro) was used as the potential drug target. Resulted information showed that the more compounds of LH added, the higher medication efficacy obtained using multi-method integrated screening system, expert consultation method, and molecular dynamics simulation. Pharmacodynamic mechanism analysis showed that low total energy and polar surface area of LH active compound (i.e., β-sitosterol) will contribute to the best therapeutic effect on COVID-19 using quantitative structure-activity relationships (QSAR) and sensitivity models. Additionally, when mild COVID-19 patients take LH with the optimum dietary scheme (i.e., β-lactoglobulin, α-lactalbumin, vitamin A, vitamin B, vitamin C, carotene, and vitamin E), the medication efficacy were significantly improved (23.58%). Pharmacokinetics and toxicokinetics results showed that LH had certain human health risks and ecotoxicity. This study revealed the multi-compound interaction mechanism of LH treatment on COVID-19, and provided theoretical guidance for improving therapeutic effect, evaluating TCM safety, and preventing human health risk.
Graphical abstractThis review summarizes research data on the pharmaceutical drugs used to treat the novel SARS-CoV-2 virus, their characteristics, environmental impacts, and the advanced oxidation processes (AOP) applied to remove them. A literature survey was conducted using the electronic databases Science Direct, Scopus, Taylor & Francis, Google Scholar, PubMed, and Springer. This complete research includes and discusses relevant studies that involve the introduction, pharmaceutical drugs used in the SARS-CoV-2 pandemic: chemical characteristics and environmental impact, advanced oxidation process (AOP), future trends and discussion, and conclusions. The results show a full approach in the versatility of AOPs as a promising solution to minimize the environmental impact associated with these compounds by the fact that they offer different ways for hydroxyl radical production. Moreover, this article focuses on introducing the fundamentals of each AOP, the main parameters involved, and the concomitance with other sources and modifications over the years. Photocatalysis, sonochemical technologies, electro-oxidation, photolysis, Fenton reaction, ozone, and sulfate radical AOP have been used to mineralize SARS-CoV-2 pharmaceutical compounds, and the efficiencies are greater than 65%. According to the results, photocatalysis is the main technology currently applied to remove these pharmaceuticals. This process has garnered attention because solar energy can be directly utilized; however, low photocatalytic efficiencies and high costs in large-scale practical applications limit its use. Furthermore, pharmaceuticals in the environment are diverse and complex. Finally, the review also provides ideas for further research needs and major concerns.
Graphical abstractThe present study validates the oil-based paint bioremediation potential of Bacillus subtilis NAP1 for ecotoxicological assessment using a three-dimensional multi-species bio-testing model. The model included bioassays to determine phytotoxic effect, cytotoxic effect, and antimicrobial effect of oil-based paint. Additionally, the antioxidant activity of pre- and post-bioremediation samples was also detected to confirm its detoxification. Although, the pre-bioremediation samples of oil-based paint displayed significant toxicity against all the life forms. However, post-bioremediation, the cytotoxic effect against Artemia salina revealed substantial detoxification of oil-based paint with LD50 of 121 μl ml?1 (without glucose) and >?400 μl ml?1 (with glucose). Similarly, the reduction in toxicity against Raphanus raphanistrum seeds germination (%FG?=?98 to 100%) was also evident of successful detoxification under experimental conditions. Moreover, the toxicity against test bacterial strains and fungal strains was completely removed after bioremediation. In addition, the post-bioremediation samples showed reduced antioxidant activities (% scavenging?=?23.5?±?0.35 and 28.9?±?2.7) without and with glucose, respectively. Convincingly, the present multi-species bio-testing model in addition to antioxidant studies could be suggested as a validation tool for bioremediation experiments, especially for middle and low-income countries.
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Understanding the interaction between microorganisms and fluid dynamics is important for aquatic ecosystems, though only sporadic attention has been focused on this topic in the past. In this study, particular attention was paid to the phenol-degrading bacterial strains Microbacterium oxydans LY1 and Alcaligenes faecalis LY2 subjected to controlled fluid flow under laboratory conditions. These two strains were found to be able to degrade phenols over a concentration range from 50 to 500 mg/L under different turbulence conditions ranging from 0 to 250 rpm. The time it took to reach total phenol degradation decreased when the turbulence was increased in both strains, with increasing energy dissipation rates ranging from 0.110 to 6.241 W/kg, corresponding to changes in the bacterial diffusive sublayer thickness (δ) and enhanced oxygen uptake. Moreover, the maximum specific growth rates of the two strains also increased with the enhancement of turbulence. A model integrating growth inhibition and fluid motion was proposed based on the self-inhibition Haldane model by introducing a turbulence parameter, α. The resulting modified Haldane model was designed to include fluid motion as a variable in the quantification of the physiological responses of microorganisms. This modified Haldane model could be considered a useful laboratory reference when modeling procedures for water environment bioremediation.
Cell nutrition uptake cartoon schematic diagram for M. oxydans LY1 under different turbulent condition (50 and 200 rpm).