A state-of-the-art review of quinoline degradation and technical bottlenecks

Two-way role of iron-carbon in biochemical reactions: Microelectrolysis and enhanced activity of aerobic granular sludge for efficient refractory wastewater treatment

Industrial wastewater contained a large amount of refractory organics, and single treatment processes had limitations. This study investigated the mechanism of refractory organics removal using iron-carbon built-in coupled activated sludge (ICAS) and explored the role and function of iron-carbon (IC) within the ICAS system. The aerobic granular sludge (AGS) cultivated with IC exhibited a loose surface and a tight interior structure. Iron in the AGS concentrated near the outer layer to form a crust, which protected the inner microorganisms. IC promoted EPS secretion and regulated the abundance of positive and negative signaling molecules to maintain AGS stability. Experiments using quinoline as a model refractory organic showed that both physical adsorption by IC and biological adsorption by sludge rapidly fixed a large amount of pollutants, providing a buffer capacity for the system. The iron mineral crust on the AGS surface enhanced quinoline adsorption. Hydroxylation was the first step in quinoline degradation, with IC upregulating the genes iorA/B, qorB, and wrbA involved in this process, and the relative abundances of quinoline-degrading bacteria. Both pyridine ring opening and benzene ring cleavage occurred in the single IC system, and the microelectrolysis process produced •OH and [H], which made degradation pathway for quinoline through IC more complex than microbial degradation. Although the IC-mediated pathway accounted for only a small part of overall quinoline removal in the ICAS system, the ICAS system not only preserved the microelectrolysis process but also enhanced microbial metabolic activity. This work provided insights into the synergistic removal of pollutants and maintenance of AGS stability by the ICAS process, ensuring efficient treatment of refractory organic wastewater.

Visible-light-induced synthesis of 2,4-disubstituted quinolines from o-vinylaryl isocyanides and oxime esters

A visible-light-induced radical cyclization reaction of o-vinylaryl isocyanides and oxime esters to access various 2,4-disubstituted quinolines was disclosed. Oxime esters were employed as acyl radical precursors via the carbon-carbon bond cleavage. It provided an effective way for the synthesis of 2-acyl-4-arlysubstituted quinolines under mild conditions and exhibited good functional group tolerance and substrate applicability.

Effective degradation of quinoline by catalytic ozonation with MnCexOy catalysts: performance and mechanism

Quinoline inevitably remains in the effluent of coking wastewater treatment plants due to its bio-refractory nature, which might cause unfavorable effects on human and ecological environments. In this study, MnCexOy was consciously synthesized by α-MnO2 doped with Ce3+ (Ce:Mn = 1:10) and employed as the ozonation catalyst for quinoline degradation. After that, the removal efficiency and mechanism of quinoline were systematically analyzed by characterizing the physicochemical properties of MnCexOy, investigating free radicals and monitoring the solution pH. Results indicated that the removal rate of quinoline was greatly improved by the prepared MnCexOy catalyst. Specifically, the removal efficiencies of quinoline could be 93.73, 62.57 and 43.76%, corresponding to MnCexOy, α-MnO2 and single ozonation systems, respectively. The radical scavenging tests demonstrated that •OH and •O2- were the dominant reactive oxygen species in the MnCexOy ozonation system. Meanwhile, the contribution levels of •OH and •O2- to quinoline degradation were about 42 and 35%, respectively. The abundant surface hydroxyl groups and oxygen vacancies of the MnCexOy catalyst were two important factors for decomposing molecular O3 into more •OH and •O2-. This study could provide scientific support for the application of the MnCexOy/O3 system in degrading quinoline in bio-treated coking wastewater.

Study of the biofilm mechanism of C4-HSL and C6-HSL in the degradation of quinoline

Quinoline is a hard-to-degrade organic compound widely found in coal chemical wastewater, that seriously affects the ecological environment and human health. A number of biochemical methods are already available for quinoline degradation, but the use of microbial community sensing for quinoline degradation has not been studied in depth. Therefore, this paper focuses on the enhanced mechanism of quorum-sensing signaling molecules in the biofilm formation process during quinoline degradation by functional strains of bacteria. In this paper, the effects of the signal molecules C4-HSL and C6-HSL on the adhesion ability, colony diameter, biofilm formation ability and biofilm morphology of functional strains of quinoline degrading bacteria (Ochrobactrum sp., LC-1) were investigated, and the results showed that both signal molecules promoted the biofilm formation process during the degradation of quinoline by exhibiting an efficient biofortification effect. Both signal molecules could enhance the colony diameter of strain LC-1, where C4-HSL could enhance the biomass of strain LC-1 and stimulate the secretion of extracellular polysaccharides; and C6-HSL could induce the enhancement of adhesion performance and the secretion of extracellular proteins from strain LC-1; both molecules together enhanced the biofilm formation process of strain LC-1. This study has practical application in the degradation of quinoline in coal chemical wastewater.

Progression and expansion of quinoline as bioactive moiety: a patent review

Quinoline inhibitors are appealing medicinal products for a range of illnesses and problems. It is bicyclic heterocyclic scaffold has been intensively employed in pharmacological research and is well known for its wide range of biological purposes. Biological activities exhibited by quinoline derivatives, such as anti-inflammatory properties, antioxidant, antimicrobial, anti-tubercular, antidiabetic, anti-malarial and others are covered in detail in this review. The IC50 of patented inhibitors might range from nm to μM range, based on the experiments used. It presents an outline of patents file between 2002 and 2023 concerning to biological activities by quinoline derivatives. As a result, it is critical to develop additional chemical quinoline core alterations for novel chemical compounds and enhanced pharmacological impacts.

Strategic analysis on development of simultaneous adsorption and catalytic biodegradation over advanced bio-carriers for zero-liquid discharge of industrial wastewater

With rapid industrial development, millions of tons of industrial wastewater are produced that contain highly toxic, carcinogenic, mutagenic compounds. These compounds may consist of high concentration of refractory organics with plentiful carbon and nitrogen. To date, a substantial proportion of industrial wastewater is discharged directly to precious water bodies due to the high operational costs associated with selective treatment methods. For example, many existing treatment processes rely on activated sludge-based treatments that only target readily available carbon using conventional microbes, with limited capacity for nitrogen and other nutrient removal. Therefore, an additional set-up is often required in the treatment chain to address residual nitrogen, but even after treatment, refractory organics persist in the effluents due to their low biodegradability. With the advancements in nanotechnology and biotechnology, novel processes such as adsorption and biodegradation have been developed, and one promising approach is integration of adsorption and biodegradation over porous substrates (bio-carriers). Regardless of recent focus in a few applied researches, the process assessment and critical analysis of this approach is still missing, and it highlights the urgency and importance of this review. This review paper discussed the development of the simultaneous adsorption and catalytic biodegradation (SACB) over a bio-carrier for the sustainable treatment of refractory organics. It provides insights into the physico-chemical characteristics of the bio-carrier, the development mechanism of SACB, stabilization techniques, and process optimization strategies. Furthermore, the most efficient treatment chain is proposed, and its technical aspects are critically analysed based on updated research. It is anticipated that this review will contribute to the knowledge of academia and industrialist for sustainable upgradation of existing industrial wastewater treatment plants.

Rhodococcus Strains from the Specialized Collection of Alkanotrophs for Biodegradation of Aromatic Compounds

The ability to degrade aromatic hydrocarbons, including (i) benzene, toluene, o-xylene, naphthalene, anthracene, phenanthrene, benzo[a]anthracene, and benzo[a]pyrene; (ii) polar substituted derivatives of benzene, including phenol and aniline; (iii) N-heterocyclic compounds, including pyridine; 2-, 3-, and 4-picolines; 2- and 6-lutidine; 2- and 4-hydroxypyridines; (iv) derivatives of aromatic acids, including coumarin, of 133 Rhodococcus strains from the Regional Specialized Collection of Alkanotrophic Microorganisms was demonstrated. The minimal inhibitory concentrations of these aromatic compounds for Rhodococcus varied in a wide range from 0.2 up to 50.0 mM. o-Xylene and polycyclic aromatic hydrocarbons (PAHs) were the less-toxic and preferred aromatic growth substrates. Rhodococcus bacteria introduced into the PAH-contaminated model soil resulted in a 43% removal of PAHs at an initial concentration 1 g/kg within 213 days, which was three times higher than that in the control soil. As a result of the analysis of biodegradation genes, metabolic pathways for aromatic hydrocarbons, phenol, and nitrogen-containing aromatic compounds in Rhodococcus, proceeding through the formation of catechol as a key metabolite with its following ortho-cleavage or via the hydrogenation of aromatic rings, were verified.

Heterogeneous electro-Fenton using three-dimension Fe-Co-Bi/kaolin particle electrodes for degradation of quinoline in wastewater

Wastewater containing quinoline has become a common pollutant in water and soil environments, which poses a threat to human health due to its carcinogenicity, teratogenicity, and mutagenicity. Quinoline's stability and toxicity hinders its degradation by conventional physicochemical and biological methods. In this contribution, Fe-Co-Bi/kaolin particle electrodes were prepared for the efficient degradation of quinoline in wastewater, and characterized by using scanning electron microscope, X-ray diffraction, pyridine-IR, Brunauer-Emmett-Teller, X-ray photoelectron spectroscopy, and four-probe resistivity test. Parameters affecting the degradation efficiency were optimized to be the particle electrode dosage of 40 g/L, pH 3.5, H₂O₂ addition of 67.6 mmol/L, electrical conductivity of 12.7 ms/cm, and voltage of 20 V. The constructed three-dimensional catalytic particle electrode system (3D-CPE) achieved 92.1% removal rate of chemical oxygen demand (COD) under the optimal conditions. Hydroxyl radicals (•OH) generated in the 3D-CPE process were identified by radical scavenging tests and electron spin response analysis. To unravel the degradation mechanism, the intermediate products were identified by using high performance liquid chromatography-mass spectrometry. The degradation mechanism was discussed with the help of theoretical calculation.

Biochar and wood ash amended anaerobic digestion of hydrothermally pretreated lignocellulosic biomass for biorefinery applications

This study investigated the effect of biochar and wood ash amendment on the anaerobic digestion of hydrothermally pretreated lignocellulosic biomass. Hydrothermal pretreatment was performed on switchgrass at 200, 250, and 300 °C with 0, 30, and 60 min of retention times. The pretreatment method was optimized using the response surface method for enhanced methane production. At the optimum pretreatment (200 °C/0 min retention time), a specific methane yield of 256.9 mL CH4/g volatile solids (VS), corresponding to an increase of 32.8% with respect to the untreated substrate, was obtained. Hydrothermal pretreatment was beneficial for methane production at temperatures lower than 220 °C and retention times shorter than 20 min. At more severe pretreatment conditions than 220°-20 min, sugars were degraded into other products, causing a decrease in the methane yield. The hydrothermal degradation products, i.e., acetic acid, lactic acid, furfural, and hydroxymethylfurfural concentrations, were also measured and modeled. The addition of biochar and wood ash to BMP assays were tested at 2, 9, 16 g/g VSinoculum ratios and <63, 63-125, 125-250 μm particle sizes. A decline in methane production was observed for all tested doses and particle sizes of both additives. The decline in the methane potential was proportional to the doses and particle sizes. Kinetic modeling of BMP test results also supported that using the additives was not beneficial. Based on the result of this study, it was found that the use of biochar and wood ash in a pretreated lignocellulosic biomass processing biorefinery would not be beneficial.

Biodegradation time series characteristics and metabolic fate of different aromatic compounds in the biochemical treatment process of coal chemical wastewater

In this study, the biochemical treatment system of coal chemical wastewater (CCW) was constructed to degrade aromatic compounds. The biodegradation time series characteristics of 8 benzene series (BTEX), 6 phenols, 10 polycyclic aromatic hydrocarbons (PAHs), and 3 nitrogen heterocyclic compounds (NHCs) were detected. The aim was to clarify the storage characteristics and dynamic transformation in water, EPS, and cells of these aromatic compounds. The results showed that BTEX and NHCs were more easily degraded than PAHs and phenols. Furthermore, aromatic compounds were initially adsorbed into EPS from water by microorganisms. Then, some were degraded, and others were transferred into the cell. Finally, they were completely degraded. The percentage of surplus content with them in EPS and cells were PAHs > phenols > NHCs = BTEX. The study could lay a theoretical foundation for the regulation and harmless treatment of the CCW in the stable operation of the biochemical treatment system.

Biodegradation characteristics and mechanism of quinoline by Ochrobactrum sp. strain C2

A quinoline-degrading strain, C2, which could completely degrade 250 mg/L of quinoline within 24 h, was isolated from coking wastewater. Strain C2 was identified as Ochrobactrum sp. on the basis of 16S rDNA sequence analysis According to 16S rDNA gene sequence analysis, Strain C2 was identified as Ochrobactrum sp. Strain C2 could utilize quinoline as the sole carbon sources and nitrogen sources to grow and degrade quinoline well under acidic conditions. The optimum inoculum concentration, temperature and shaking speed for quinoline degradation were 10%, 30 °C and 150 r/min, respectively. The degradation of quinoline at low concentration by the strain followed the first-order kinetic model. The growth process of strain C2 was more consistent with the Haldane model than the Monod model, and the kinetic parameters were: Vmax = 0.08 h^-1, Ks = 131.5 mg/L, Ki = 183.1 mg/L. Compared with suspended strains, strain C2 immobilized by sodium alginate had better degradation efficiency of quinoline and COD. The metabolic pathway of quinoline by Strain C2 was tentatively proposed, quinoline was firstly converted into 2(1H) quinolone, then the benzene ring was opened with the action of catechol 1,2-dioxygenase and subsequently transformed into benzaldehyde, 2-pentanone, hydroxyphenyl propionic acid and others.

TrendProbe: Time profile analysis of emerging contaminants by LC-HRMS non-target screening and deep learning convolutional neural network

Peak prioritization is one of the key steps in non-target screening of environmental samples to direct the identification efforts to relevant and important features. Occurrence of chemicals is sometimes a function of time and their presence in consecutive days (trend) reveals important aspects such as discharges from agricultural, industrial or domestic activities. This study presents a validated computational framework based on deep learning conventional neural network to classify trends of chemicals over 30 consecutive days of sampling in two sampling sites (upstream and downstream of a river). From trend analysis and factor analysis, the chemicals could be classified into periodic, spill, increasing, decreasing and false trend. The developed method was validated with list of 42 reference standards (target screening) and applied to samples. 25 compounds were selected by the deep learning and identified via non-target screening. Three classes of surfactants were identified for the first time in river water and two of them were never reported in the literature. Overall, 21 new homologous series of the newly identified surfactants were tentatively identified. The aquatic toxicity of the identified compounds was estimated by in silico tools and a few compounds along with their homologous series showed potential risk to aquatic environment.

Biodegradation of Quinoline by a Newly Isolated Salt-Tolerating Bacterium Rhodococcus gordoniae Strain JH145

Quinoline is a typical nitrogen-heterocyclic compound with high toxicity and carcinogenicity which exists ubiquitously in industrial wastewater. In this study, a new quinoline-degrading bacterial strain Rhodococcus sp. JH145 was isolated from oil-contaminated soil. Strain JH145 could grow with quinoline as the sole carbon source. The optimum growth temperature, pH, and salt concentration were 30 °C, 8.0, and 1%, respectively. 100 mg/L quinoline could be completely removed within 28 h. Particularly, strain JH145 showed excellent quinoline biodegradation ability under a high-salt concentration of 7.5%. Two different quinoline degradation pathways, a typical 8-hydroxycoumarin pathway, and a unique anthranilate pathway were proposed based on the intermediates identified by liquid chromatography–time of flight mass spectrometry. Our present results provided new candidates for industrial application in quinoline-contaminated wastewater treatment even under high-salt conditions.