•Five types of biomass from MBBR, IFAS, and MBR were compared for the degradation of OSPW.•MBBR and IFAS-biofilm showed high AEF and classical NAs removal, MBR-flocs showed high COD removal.•NAs ...degradation was highly dependent on the carbon number and NA cyclization number according to UPLC/HRMS analysis.•Denitrifiers were more abundant in suspended phase of activated sludge flocs.
This study compared microbial characteristics and oil sands process-affected water (OSPW) treatment performance of five types of microbial biomass (MBBR-biofilm, IFAS-biofilm, IFAS-floc, MBR-aerobic-floc, and MBR-anoxic-floc) cultivated from three types of bioreactors (MBBR, IFAS, and MBR) in batch experiments. Chemical oxygen demand (COD), ammonium, acid extractable fraction (AEF), and naphthenic acids (NAs) removals efficiencies were distinctly different between suspended and attached bacterial aggregates and between aerobic and anoxic suspended flocs. MBR-aerobic-floc and MBR-anoxic-floc demonstrated COD removal efficiencies higher than microbial aggregates obtained from MBBR and IFAS, MBBR and IFAS biofilm had higher AEF removal efficiencies than those obtained using flocs. MBBR-biofilm demonstrated the most efficient NAs removal from OSPW. NAs degradation efficiency was highly dependent on the carbon number and NA cyclization number according to UPLC/HRMS analysis. Mono- and di-oxidized NAs were the dominant oxy-NA species in OSPW samples. Microbial analysis with quantitative polymerase chain reaction (q-PCR) indicated that the bacterial 16S rRNA gene abundance was significantly higher in the batch bioreactors with suspended flocs than in those with biofilm, the NSR gene abundance in the MBR-anoxic bioreactor was significantly lower than that in aerobic batch bioreactors, and denitrifiers were more abundant in the suspended phase of the activated sludge flocs.
The critical issue in developing mature Oxy-Coal Combustion Steam System technology could be the reactivity of demineralized coal which, is closely related to its chemical structure. The chemical ...structures of Liupanshui raw coal (LPS-R) and Liupanshui demineralized coal (LPS-D) were analyzed by FTIR and solid-state
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C-NMR. The pyrolysis experiments were carried out by TG, and the pyrolysis kinetics was analyzed by three iso-conversional methods. FTIR and
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C-NMR results suggested that the carbon structure of LPS coal was not altered greatly, while demineralization promoted the maturity of coal and the condensation degree of the aromatic ring, making the chemical structure of coal more stable. The oxygen-containing functional groups with low bond energy were reduced, and the ratio of aromatic carbon with high bond energy was increased, decreasing the pyrolysis reactivity. DTG curve-fitting results revealed that the thermal weight loss of LPS coal mainly came from the cleavage of aliphatic covalent bonds. By pyrolysis kinetics analysis of LPS-R and LPS-D, the apparent activation energies were 76 ± 4 to 463 ± 5 kJ/mol and 84 ± 2 to 758 ± 12 kJ/mol, respectively, under different conversion rates. The reactivity of the demineralized coal was inhibited to some extent, as the apparent activation energy of pyrolysis for LPS-D increased by acid treatment.
Geothermal energy is a clean energy source to fulfill the increasing global energy demands. For the first time, several energy extraction strategies are proposed and compared through numerical ...simulations for effective energy recovery from low-permeability geothermal reservoirs. We simulate geothermal energy extraction using either Cyclic Water Injection (CWI) or Water-Assisted Gravity Drainage (WAGD) processes with or without hydraulic fracturing over a 10-year operation. We evaluate the positioning of injector and producer in WAGD process, well spacing, addition of one injector, and the time variation of injection/soaking periods in CWI process. The simulations indicate that the fractured reservoirs generate more energy than those without fracturing; CWI-based processes exhibit higher energy recovery efficiency than WAGD process in terms of Energy-Water-Ratio (EWR). EWR, as a newly proposed parameter in this study, is defined as the energy production specific to per unit volume of water injected, which is useful in evaluating the cost-effectiveness of a geothermal energy extraction process. The gravitational effect proves to be the dominant factor that determines energy generation compared to phase change in WAGD process. In addition, formation and impacts of steam chambers in CWI and WAGD-based processes are discussed. Furthermore, statistical analyses are performed to evaluate the effects of reservoir temperature, pressure, permeability, and their mutual interactions on cumulative energy production. Eventually, two correlation models for predicting cumulative energy production based on these formation properties are proposed. This study provides a new perspective on implementing different innovative exploration strategies and optimization processes for energy extraction from low-permeability geothermal reservoirs.
•9 production scenarios are simulated for a 3D geothermal reservoir model.•CWI and WAGD are proposed and simulated for low-permeability geothermal reservoirs.•CWI-based processes are compared with WAGD-based processes.•EWR is a useful indicator to evaluate geothermal production efficiency.•Formation and effect of steam chambers in CWI and WAGD processes are discussed.
•The definition, classification, and sources of polyphenols are provided.•The properties of polyphenols (reduction and chelation) on iron are presented.•The metal chelation activity of polyphenols is ...related to ortho-dihydroxy groups.•Polyphenols reduce Fe(III) to Fe(II) via a one-electron transfer pathway.•The application of polyphenols in Fenton/Fenton-like reactions is reviewed.
Polyphenols are aromatic substances with one or more hydroxyl groups together with other substituents attached to aromatic rings. Polyphenols can be found in regular foods and drinks, including teas, coffee, vegetables, fruits, etc. Polyphenols have anti-oxidant, pro-oxidant, anti-histamine, anti-bacterial, anti-inflammatory, and anti-viral properties. They present chelation and reduction activities to iron ion and the anti-oxidant properties are mainly induced by the iron chelation effect. The metal chelation activity of polyphenols is primarily related to the presence of ortho-dihydroxy groups. Polyphenols can reduce Fe(III) to Fe(II) via a one-electron transfer pathway and they are oxidized to semiquinones. Due to the chelation and reduction properties, polyphenols are applied by researchers to promote the efficiency of Fenton/Fenton-like reactions for contaminant removal. The application of polyphenols in Fenton/Fenton-like reactions is reviewed in this article for the first time. The polyphenols reviewed include dihydroxybenzenes (such as catechol and hydroquinone), phenolic acids (such as gallic acid, protocatechuic acid, and tannic acid), flavonoids (such as catechin and epigallocatechin-3-gallate), and polyphenol extracts from tea, woods, coffee, etc. As a substance that pervades almost every aspect of human life, polyphenols present promising effect on the waste treatment in the environmental field, which deserves more studies.
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•Real river and lake water with carboxylated PS microplastics were treated via CFS.•Higher alum doses generally benefited the removal of PS microplastics ≤ 90 μm.•Smaller PS ...microplastics were better removed by alum CFS treatment.•Water source affected the removal efficiency of PS microplastics.•PS microplastics did not impact the removal of turbidity, NOM fractions, or metals.
Microplastics are an emerging issue in water systems, and an understanding of their occurrence and behavior is complicated by a high diversity in physical (i.e., size and shape) and chemical characteristics. To date, there have been limited studies on microplastics in drinking water treatment processes. As the coagulation-flocculation-sedimentation (CFS) process is the first step of the particle/colloid removal at many plants, its ability to remove microplastics requires further investigation. By performing alum-CFS bench tests, this study examined the removal of carboxylated polystyrene (PS) microspheres in a wide size range (3, 6, 25, 45, and 90 μm) in two types of real surface waters (Grand River and Lake Erie water) that are sources for full-scale drinking water treatment plants. Based on experiments using water from the Grand River with a variety of alum doses (10, 20, 30, 40, and 50 mg/L), a higher alum dose generally led to better removal of microspheres smaller than 90 μm, while an alum dose > 30 mg/L did not substantially improve the removal of particles between 3 and 25 μm. Further experiments indicated that smaller PS microspheres were more effectively removed in both river (Grand River_Dec 06) and lake water (Lake Erie_Nov 29). For example, with an alum dose of 30 mg/L, 75.6 and 85.2% of the 6-μm PS microspheres were removed from Grand River and Lake Erie water, respectively. Moreover, the water source significantly (p = 0.0021) affected the removal of PS microspheres, which may have been primarily related to the difference in turbidity. No impacts of PS microspheres were observed on the removal efficiency for turbidity, natural organic matter fractions, or major metal elements by alum-CFS treatment.
•The types and properties of polyphenol-containing wastewaters are reviewed.•The treatment of polyphenol-containing wastewaters by Fenton reaction is reviewed.•The properties of several individual ...polyphenols are summarized.•The degradation of individual polyphenols by Fenton reaction is reviewed.•The reaction mechanisms of •OH with polyphenols are discussed.
Polyphenols commonly exist in agro-industrial wastewaters, such as soft drink wastewater, cork wastewater, oil mill wastewater, landfill leachate, pulp mill wastewater, winery wastewater, and tannery wastewater. Polyphenols at high concentration tend to suppress or even eliminate the efficiency of biological wastewater treatment processes. Fenton/Fenton-like reactions as complementary treatments to biological processes have been reviewed in this article for the removal of polyphenols in the above wastewaters. Only a few researchers have taken advantage of the chelating and reducing properties of polyphenols and used polyphenol-containing wastewaters, such as cork wastewater and oil mill wastewater, to enhance the efficiency of Fenton/Fenton-like processes for the treatment of other contaminants. Some other researchers use individual polyphenols such as gallic acid, protocatechuic acid, and catechol as models of polyphenol-containing wastewaters. The treatment of these compounds by Fenton/Fenton-like reactions is also reviewed in this article. In the Fenton/Fenton-like processes, hydroxyl radical (•OH) is considered as the main species for decomposing polyphenols. The possible reaction mechanisms of •OH with polyphenols is discussed, as well as the reaction impact factors, including the number and position of hydroxyl groups in phenolic rings and the properties of other functional groups (electron-donating groups or electron-withdrawing groups). The •OH attack on phenolic compounds (e.g. phenol) in Fenton reaction can generate polyphenols, which, in turn, enhances the efficiency of Fenton process.
Aerobic granular sludge (AGS) is promising for water resource recovery. Despite the mature granulation strategies in sequencing batch reactor (SBR), the application of AGS-SBR in wastewater treatment ...is usually costly as it requires extensive infrastructure conversion (e.g., from continuous-flow reactor to SBR). In contrast, continuous-flow AGS (CAGS) that does not require such infrastructure conversion is a more cost-effective strategy to retrofit existing wastewater treatment plants (WWTPs). Formation of aerobic granules in both batch and continuous-flow mode depends on many factors, including selection pressure, feast/famine conditions, extracellular polymeric substances (EPS), and environmental conditions. Compared with AGS in SBR, creating proper conditions to facilitate granulation in continuous-flow mode is challenging. Researchers have been seeking to tackle this bottleneck by studying the impacts of selection pressure, feast/famine conditions, and operating parameters on granulation and granule stability in CAGS. This review paper summarizes the state-of-the-art knowledge regarding CAGS for wastewater treatment. Firstly, we discuss the CAGS granulation process and effective parameters (i.e., selection pressure, feast/famine conditions, hydrodynamic shear force, reactor configuration, the role of EPS, and other operating factors). Then, we evaluate CAGS performance in removing COD, nitrogen, phosphorus, emerging pollutants, and heavy metals from wastewater. Finally, the applicability of the hybrid CAGS systems is presented. At last, we suggest that integrating CAGS with other treatment methods such as membrane bioreactor (MBR) or advanced oxidation processes (AOP) can benefit the performance and stability of granules. However, future research should address unknowns including the relationship between feast/famine ratio and stability of the granules, the effectiveness of applying particle size-based selection pressure, and the CAGS performance at low temperatures.
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•Treatment efficiency and stability of CAGS is comparable to AGS-SBR.•Selection pressure and feast/famine conditions are critical to CAGS granulation.•Selection pressure can be based on particle size instead of settling velocity.•Hybrid CAGS systems can be advantageous over standalone CAGS.•CAGS is highly effective in the removal of emerging pollutants from wastewater.
•The 2D structure model of Zhundong coal was obtained by a13C-NMR, FTIR, XPS.•The angle, atomic vibration, bond torsion and inversion of the 2D structure was optimized to obtain the 3D energy-minimum ...conformation.•The 2D structure was verified by using 13C-NMR simulation.•The 3D structure was verified by using FTIR simulation.
Understanding the coal molecular structure is of paramount importance for the effective utilization of coal. In this paper, the molecular structure of Zhundong coal (ZD) was characterized by physical detection techniques, such as solid state 13C nuclear magnetic resonance spectroscopy (13C-NMR), fourier transform infrared resonance spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). The occurrence and distribution of aromatic carbocyclic frameworks were analyzed by 13C-NMR. Based on the FTIR and XPS analysis, the existing forms and the length of the aliphatic chain, the substitution forms of aromatic carbocyclic rings, and different types of functional groups were confirmed. The aliphatic chains and functional groups were introduced into these aromatic carbocyclic frameworks, and the 2D molecular structures model of ZD with the molecular chemical formula as C179H124O21N4 were constructed. The simulated 13C-NMR spectra of which were consistent with the experimental spectra, indicating the accuracy of the 2D ZD molecular structure model. Efforts were made to obtain the energy-minimum conformation of the 3D molecular structure by molecular mechanics (MM) and molecular dynamics (MD). The simulated FTIR spectra of the model were in good agreement with the experimental results, which fully verified the accuracy of the ZD molecular structure. The molecular structure provides a deep reference to understand the structural characteristics of ZD coal at the molecular micro-scale, which would be helpful to understand the reactivity of ZD coal.
This paper reviews studies published in 2019, in the area of analytical techniques for determination of pesticides and herbicides. It should be noted that some of the reports summarized in this ...review are not directly related to but could potentially be used for water environment studies. Based on different methods, the literatures are organized into six sections, namely extraction methods, electrochemical techniques, spectrophotometric techniques, chemiluminescence and fluorescence methods, chromatographic and mass spectrometric techniques, and biochemical assays.
Practitioner points
Totally 141 research articles have been summarized.
The review is divided into six parts.
Chromatographic and mass spectrometric techniques are the most widely used methods.
The effect of –COOH and –NH2 functional groups on adsorptive polysaccharide fouling of a membrane surface was investigated at different pH values. Sodium alginate (SA: rich in –COOH) and chitosan ...(CTS: rich in –NH2) were selected as typical polysaccharides adsorbed onto the surface of polyvinylidene fluoride (PVDF) and PVDF modified using graphene oxide (GO-PVDF). The adsorption behavior and structure of the fouling layer were determined using quartz crystal microbalance and dissipation (QCM-D) and atomic force microscopy (AFM). The results showed that in the pH range of 4–6, the adherence of polysaccharide fouling and its reversibility were dependent on functional groups. When the organics were rich in –COOH, increase in the pH reduced their deposition on the membrane surface, and alleviated adsorptive fouling and its irreversibility. For the –NH2 functional group, the increase in pH led to more severe polysaccharide fouling due to the decreased degree of protonation, and the resulting fouling maintained high irreversibility. Modification using GO alleviated the adsorptive fouling of these two polysaccharides on PVDF; however, the extent of alleviation was dependent on the abundance of functional groups on the polysaccharides.
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•Severity of polysaccharide fouling at different pH is functional group dependent.•Fouling of polysaccharide rich in –COOH alleviate as pH increases.•Fouling of polysaccharide rich in –NH2 becomes more severe as pH increases.•GO-PVDF membrane alleviate polysaccharide fouling under investigated pH range.
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