1,720,978 research outputs found
Current status, potential assessment, and future directions of biological treatments of unconventional oil and gas wastewater
No full textUnconventional oil and gas (UOG) extraction techniques typically involve the production of large volumes of so-called flowback and produced water (FPW), a site-specific wastewater stream characterized by complex organic and inorganic composition. Sustainable and cost-effective management of FPW, as well as mitigation of its environmental risks and impacts, represents substantial challenges for governments, industries, and societies worldwide. Among various treatment technologies, biological processes have gained interest due to their low installation and operational costs. However, the interaction of FPW's complex composition with microorganisms poses challenging scientific and engineering questions. This review examines the water quality characteristics and sources of FPW from twelve UOG extraction sites in China and North America, revealing strong spatio-temporal heterogeneity of organic, inorganic, and microbial components across different reservoirs. The complex and variable water quality, large wastewater volumes, and high treatment demands have driven the exploration of biological treatments for FPW. This work systematically reviews and analyzes the operating conditions, treatment efficiency, and technical applicability of suspended sludge reactors, attached sludge reactors, mixed systems, and resource/energy recovery systems. Developing skid-mounted equipment based on suspended sludge reactors to handle variations in wastewater quantity and innovating the form of attached sludge reactors, especially in enriching salt-tolerant microbes for in-situ FPW treatment, are deemed essential. The dominant microorganisms playing a key role in the biological treatment are also discussed, with focus on two different inoculation sources (activated sludge and FPW). Roseovarius from FPW and Pseudomonas from activated sludge have strong adaptability to different reactors. The review further underscores the need to integrate biological treatments with complementary technologies. Finally, it advocates for the establishment of robust and scalable biological treatments through research in three main directions: (i) exploring microbial resources in original FPW; (ii) using omics technologies to elucidate microbial function and species interaction; (iii) pre-designing environmental and operational conditions to optimize treatment efficiency
Efficiency of a combined biological aerated filter and ultrafiltration process for removal of odor compounds in rural drinking water
Full text linkEfficient recovery of lithium from spent lithium-ion battery raffinate by Mn and Al-based adsorbents: pretreatment, adsorption mechanism, and performance comparison
Full text linkAs a strong wave of retired lithium-ion battery approaches, lithium extraction from spent lithium-ion battery
raffinate (SLR) becomes increasingly critical for environmental protection and for sustainable lithium supply. To
understand the factors that affect maximum recovery of lithium from SLR, the organic and inorganic components
of SLR were initially determined. The organic matter content (up to 760.5 mg/L) seriously impacted the recovery
rate of lithium. Therefore, SLR was managed with a series of pretreatment techniques, including coagulation,
biochar aerogel adsorption, and ultrafiltration, achieving more than 84.3% removal of organic substances.
H1.33Mn1.67O4 and Li/Al layered double hydroxides adsorbents were then synthesized by solid state reaction
method and hydrothermal method, respectively, granulated into spheres with a PVC skeleton, and applied to
recycle lithium from pretreated SLR in a fixed bed adsorption column. The results indicated that both Mn and Albased
adsorbents exhibited rapid adsorption kinetics, reaching saturation within 2 h. The Mn-based adsorbent
exhibited superior adsorption selectivity for Li+ and higher Li+/Na+ separation factor (αLNia) compared to Albased
adsorbent, with partition coefficients and αLNia values equal to 6.62 mL/g, 8.79 for the former material,
and 4.92 mL/g, 8.17 for the latter. On the other hand, the Al-based adsorbent displayed better stability with
negligible Al loss, while Mn loss from the related adsorbent was less than 0.2% in every adsorption–desorption
cycle. Notably, both adsorbents demonstrated excellent reusability with their adsorption capacity maintained
after twenty adsorption–desorption cycles
Facile preparation of antifouling nanofiltration membrane by grafting zwitterions for reuse of shale gas wastewater
Full text linkComplex organic matter causes severe fouling when membranes are applied for shale gas wastewater (SGW)
treatment. This study reports the grafting of a zwitterionic polymer brush consisting of poly (sulfobetaine
methacrylate) (PSBMA) onto the surface of a commercial nanofiltration (NF) membrane via electron transferatom
transfer radical polymerization (ARGET-ATRP) to achieve anti-fouling property, especially against
organic foulants. Compared to the pristine NF membranes, the PSBMA-grafted NF membrane showed high
performance when challenged by SGW as a feed stream: (1) The flux stability was significantly improved during
long-term operation, with a 64.28% increase in flux normalization at 50% recovery rate of SGW, while maintaining
a suitable initial flux and near constant ion removal rate; (2) Based on excitation-emission-matrix spectra
integrated in the fluorescence region, the removal of protein-like organic matters and humus-like organic matters
increased by 34% and 16.5%, respectively; (3) The XDLVO theory supports the hypothesis that the hydrophobic
interactions between the membrane surface and organic foulants were reduced by enhancing the Lewis acid-base
interaction energy. The proposed anti-fouling zwitterionic membranes has potential in industrial application for
the on-site reuse of SGW
Secondary amine-activated ferrate(VI) for isoquinoline degradation: Relationship between molecular structure and reactive performance
Full text linkThis study elucidates the electronic structure-activity relationship between secondary amines and ferrate(VI) (Fe(VI)) activation. Comparative experiments demonstrated that pyrrolidine (Py) significantly outperformed diethylamine (Di) in enhancing Fe(VI)’s oxidation capability across various dosage conditions, pollutants, and water matrices. Specifically, for isoquinoline (IQL) degradation, Py-Fe(VI) achieved an approximately 7-fold higher rate constant than Fe(VI) alone, versus a 2-fold improvement observed with Di-Fe(VI). Mechanistic studies combining quenching experiments and EPR characterization corroborated Fe(IV)/Fe(V) as dominant reactive species for IQL degradation, with kinetic modeling revealing that Fe(IV) contributes > 80 % to IQL degradation in all processes. Electrochemical analysis via cyclic voltammetry and electrochemical impedance spectroscopy studies suggested that Fe(VI) activation by Di and Py might involve the formation of iron-secondary amine complexes. Density functional theory calculations highlighted Py's lower energy barrier for Fe(VI) complexation (27.7 vs. Di's 29.1 kcal/mol), accelerating activation. Secondary amines were shown to stabilize Fe(IV) via coordination, extending its reactive lifetime. Systematic evaluation of various secondary amines revealed a significant negative correlation between the highest occupied molecular orbital energy levels of amines and Fe(VI) activation performance. Moderate electron-donating capacity promotes iron complexation and pollutant degradation. This work establishes a molecular design framework for Fe(VI) activators while providing new insights into high-valent iron-mediated oxidation mechanisms, advancing sustainable water treatment strategies
Recent advances in lithium extraction from brine via solar-driven interfacial evaporation: Advanced strategies and challenges
No full text: In the framework of the green transition, the rising demand for electric vehicles and renewable energy technologies has substantially increased the need for efficient lithium extraction methods. Traditional lithium extraction methods from natural or synthetic brine are generally faced with challenges, such as high energy consumption and low efficiency, making it difficult to meet the demands for sustainable resource development. Solar interfacial evaporation technology has demonstrated substantial potential in lithium extraction due to its solar-driven process, efficient localized thermal management, and micro-interface regulation characteristics. In this review, the main methods of extracting lithium from brine and the latest progress and existing problems of lithium extraction by solar interfacial evaporation are reviewed, including coupling mechanisms between photothermal evaporation and lithium ion transport. In particular, design strategies of high-performance photothermal substrate and lithium selective functional layer, as well as the optimization path of anti-pollution and long-term stability are discussed. Furthermore, the advantages of multilayer device configurations and the optimization of three-dimensional evaporators in improving lithium extraction efficiency are analyzed. Finally, opportunities for future developments and challenges in this emerging research field are presented
Efficiency and Mechanisms of Biochar Aerogel-Assisted Biodegradation of Taste and Odor Compounds in a One-Step Membrane Bioreactor for Rural Drinking Water Production
Full text linkIn many rural areas, lakes and reservoirs represent common sources for drinking water, but these water bodies are more likely affected by taste and odor (T&O) problems that cause discomfort to consumers. T&O compounds, especially 2-methylisobornol (2-MIB) and geosmin (GSM), are not easily removed using conventional water treatment processes, and this problem is exacerbated in rural areas where treatment systems are often sparser, modest, and outdated compared to typical urban water sources. Herein, a combined process deploying biochar aerogel-supported biofilms and performed in an ultrafiltration (BAB-UF) reactor was evaluated and investigated to treat rural water polluted with 2-MIB and GSM. During a 40-day experiment, the system performance was analyzed at different values of the empty bed contact time (EBCT), while the microbial communities in different BAB-UF reactors were examined extensively. The process proved to be effective in removing 2-MIB and GSM, predominantly through biodegradation. Specifically, using biochar aerogels as suspended fillers in the reactor and an EBCT of roughly 1 h, the removal rate of 2-MIB/GSM was higher than 95%, and the effluent satisfied the requirements for domestic drinking water. Microorganisms with specific functions were enriched in different BAB-UF reactors and governed the transformation process, highlighting the importance of system tuning for achieving the desired biological function and hence product water quality
Overlooking the effect of alcohol quenchers can mislead mechanistic understanding in ferrate-based advanced oxidation processes
No full textAlcohols serve as effective quenchers and are widely employed to assess the role of reactive species in advanced oxidation processes (AOPs). However, this study reveals that frequently used alcohol quenchers, including tert-butanol (TBA), methanol (MA), ethanol (EA), and furfuryl alcohol (FFA), can substantially affect the ferrate (Fe(VI)) system. Firstly, the presence of alcohols was found to influence the decomposition of Fe(VI). In the pH range of 7–11, various alcohols promoted Fe(VI) decomposition, especially at pH 7–8, namely, the pH conditions often used in Fe(VI)-based advanced oxidation studies. The magnitude of Fe(VI) decomposition influenced by the alcohols was ranked as FFA > EA > MA > TBA. Secondly, alcohols may alter the formation and conversion of high-valent iron active species. Using the phenylmethyl sulfoxide (PMSO) probe, we observed that MA and TBA inhibited the removal of PMSO by Fe(VI), while FFA and EA substantially enhanced it. These results indicate that alcohols may not only influence the decomposition of Fe(VI) itself, but also affect the degradation of pollutants mediated by high-valent iron active species. These phenomena may lead to misconceptions about the mechanisms and efficacy of Fe(VI)-based AOPs. Overall, this work underscores the importance of carefully selecting quenchers in complex oxidation systems involving Fe(VI) to avoid misleading interpretations of Fe(VI) decomposition and oxidation behavior
Ultra-efficient degradation of isoquinoline from shale gas wastewater with the diethylamine-ferrate(VI) system: The key role of Fe(IV)/Fe(V) active species
Full text linkAlthough isoquinoline (IQL) in shale gas wastewater contributes minimally to chemical oxygen demand, its potential high toxicity makes it an environmental risk factor that cannot be overlooked. This study introduces a synergistic diethylamine (Di)/ferrate (Fe(VI)) system for efficient degradation of IQL. Compared with Fe(VI) alone, the Di/Fe(VI) system demonstrated superior performance, achieving degradation efficiency of 80.5 %. The degradation rate constant of the Di/Fe(VI) system was almost 3-fold larger than that measured with Fe(VI) alone in the degradation of IQL. Mechanistic studies, including radical quenching, electron paramagnetic resonance, pre-mixed experiments, Raman spectroscopy, and probe compounds tests suggested that high-valent iron intermediates (Fe(IV/V)) were responsible for IQL degradation in the Di/Fe(VI) system. The presence of Di promoted the generation of Fe(IV)/Fe(V) by donating electrons. Based on the intermediates identified with GC-MS measurements and density functional theory calculations, three reaction pathways for IQL degradation were proposed. ECOSAR prediction and Escherichia coli toxicity tests showed that the toxicity of IQL was significantly reduced after treatment with Di/Fe(VI) system. Optimal IQL degradation occurred at higher Fe(VI)/Di concentrations and lower pH, with minimal interference from common ions or matrix components. The system also effectively degraded other organics (e.g., 2,4-di-tert-butylphenol, 6-methylquinoline, diclofenac, carbamazepine), demonstrating broad applicability for refractory pollutant treatment
-PEGMA Ultrafiltration Membranes
Full text linkPoly(vinylidene fluoride) (PVDF) is a common and inexpensive polymeric material used for membrane fabrication, but the inherent hydrophobicity of this polymer induces severe membranes fouling, which limits its applications and further developments. Herein, we prepared superwettable PVDF membranes by selecting suitable polymer concentration and blending with PVDF-graft-poly(ethylene glycol) methyl ether methacrylate (PVDF-g-PEGMA). This fascinating interfacial phenomenon causes the contact angle of water droplets to drop from the initial value of over 70° to virtually 0° in 0.5 s for the best fabricated membrane. The wetting properties of the membranes were studied by calculating the surface free energy by surface thermodynamic analysis, by evaluating the peak height ratio from Raman spectra, and other surface characterization methods. The superwettability phenomenon is the result of the synergetic effects of high surface free energy, the Wenzel model of wetting, and the crystalline phase of PVDF. Besides superwettability, the PVDF/PVDF-g-PEGMA membranes show great improvements in flux performance, sodium alginate (SA) rejection, and flux recovery upon fouling
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