Soluble Organic Matter Research Articles

Highly efficient and secure recycling of neomycin fermentation residue by optimum temperature: Nutrients release, neomycin degradation and safety evaluation

The neomycin fermentation residues (NFR) are a solid waste during neomycin production, possessing high recycling value due to their rich organic content. However, the environmentally friendly use of NFR was hindered by its rigid matrix structure and residual neomycin. In this study, the effect of temperature on the structure and bioresource properties of NFR were investigated. Meanwhile, the effect of temperature on the degradation of residual neomycin, the toxicity of neomycin degradation products, and the safety of NFR were assessed. The results indicated that the content of soluble organic matter was increased by appropriate temperature treatment through the disruption of the rigid matrix structure of the NFR. However, excessively high temperatures led to the mineralization of organic matter. Simultaneously, appropriate temperature facilitated the transformation of organic substances to humic-like acids. The neomycin in NFR was effectively degraded with the increasing temperature, and the degradation efficiency exceeded 99 % under 220 °C for 120 min. In addition, the applicability of using appropriate temperatures to degrade antibiotics in similar other AFR has been demonstrated. Neomycin degradation occurred primarily through the cleavage of the glycosidic bond and ring ether, the detachment of the amino group, and the addition of hydroxyl groups. Meanwhile, the developmental toxicity and acute toxicity of neomycin were effectively mitigated by the appropriate temperature, and a significant reduction in ecotoxicity was observed. As a result, optimum temperature treatment proved to be an efficient method for the secure recycling of NFR.

Selenite improves growth by modulating phytohormone pathways and reprogramming primary and secondary metabolism in tomato plants

Selenium (Se) is an essential micronutrient in organisms that has a significant impact on physiological activity and gene expression in plants, thereby affecting growth and development. Humans and animals acquire Se from plants. Tomato (Solanum lycopersicum L.) is an important vegetable crop worldwide. Improving the Se nutrient level not only is beneficial for growth, development and stress resistance in tomato plants but also contributes to improving human health. However, the molecular basis of Se-mediated tomato plant growth has not been fully elucidated. In this study, using physiological and transcriptomic analyses, we investigated the effects of a low dosage of selenite [Se(Ⅳ)] on tomato seedling growth. Se(IV) enhanced the photosynthetic efficiency and increased the accumulation of soluble sugars, dry matter and organic matter, thereby promoting tomato plant growth. Transcriptome analysis revealed that Se(IV) reprogrammed primary and secondary metabolic pathways, thus modulating plant growth. Se(IV) also increased the concentrations of auxin, jasmonic acid and salicylic acid in leaves and the concentration of cytokinin in roots, thus altering phytohormone signaling pathways and affecting plant growth and stress resistance in tomato plants. Furthermore, exogenous Se(IV) alters the expression of genes involved in flavonoid biosynthesis, thereby modulating plant growth and development in tomato plants. Taken together, these findings provide important insights into the regulatory mechanisms of low-dose Se(IV) on tomato growth and contribute to the breeding of Se-accumulating tomato cultivars.

Photoaging processes and mechanisms of polyolefin microplastics

The photoaging processes of microplastics (MPs) under various conditions, including environmental factors and soluble organic matter, have been extensively investigated. However, a notable gap exists in the literature regarding comparative experiments on the photoaging of polyolefin-type MPs, and research on different light sources is particularly scarce. This research involved exposing representative MPs (polystyrene (PS), polyvinyl chloride (PVC), and polyethylene (PE)) to light with different wavelength ranges (200–2000 nm and 320–780 nm). Results indicated that PS and PVC, with benzene rings and C-Cl chains, exhibited higher susceptibility to photoaging compared to PE, leading to changes in physicochemical properties. In 200–2000 nm, including UVC (200–280 nm) and UVB (280–315 nm), a pronounced PS and PVC photoaging process was observed due to their higher energy, which resulted in noticeable yellowing of the morphology. PE showed less pronounced effects, except for noticeable aging in the 320–780 nm range within 6 h (UV–vis spectrum), with a slow depolymerization rate over 72 h. Furthermore, a limited aging of polyolefins was observed under dark conditions. In summary, this study provides crucial insight into the accelerated photoaging of polyolefin-type MPs under different light source, which offers novel perspectives and references for future research directions.

Anaerobic digestion model number 1 applied to the modeling of anaerobic digestion of residues generated in soluble coffee processing

The Anaerobic Digestion Model No. 1 (ADM1) was applied in this study to simulate the anaerobic digestion (AD) of wastewaters from soluble coffee processing in sequential batch reactors. As these substrates present considerable levels of phenolic compounds, modifications were made to the basic structure of the ADM1. Additionally, the Luong inhibition model replaced the Monod model to describe the consumption of soluble organic matter. On the other hand, the removal of phenolic compounds was carried out using the Haldane model, appropriate when the inhibition by excess substrate is present, taking into account in this case the quantification of phenols and benzoic acid as total phenols. The new ADM1-based model was calibrated with experimental data from the AD of post hydrothermal wastewater (PHWW) of spent coffee grounds (SCG) and validated with experimental data of the AD of effluents produced during the soluble coffee processing. The simulation results demonstrated that the new model moderately described the removal of phenolic compounds ( > 90 %), methane production (2.243 kgCODm−3 in calibration and 6.16 kgCODm−3 in validation), and the production and consumption of organic acids over time. However, in future research new metabolic pathways may be included in the model to improve its quality even more.

Iron sulfide mineral/polylactic acid mixotrophic biofilter for simultaneous nitrate and phosphate removal

Heterotrophic denitrification based on polylactic acid (PLAHD) can remove nitrate effectively, but it is expensive and can't remove phosphate. Autotrophic denitrification based on iron sulfide (ISAD) can simultaneously remove nitrate and phosphate cost-effectively, but its nitrate rate is slow. So, iron sulfide mineral/polylactic acid mixotrophic biofilter (ISPLAB) was constructed to combine advantages of ISAD and PLAHD. ISPLAB achieved nitrogen and phosphorus removal rates of 98.04 % and 94.12 %, respectively, at a hydraulic retention time (HRT) of 24 h. The study also revealed that controlling molecular weight (Mw) of PLA improved the release of soluble organic matter; adding iron sulfide enhanced the hydrolysis of PLA and precipitated PO43− of Fe2+/Fe3+, thereby facilitated simultaneous nitrogen and phosphorus removal. Microbial community analysis resulted that denitrifying bacterias (Phaeodactylibacter and Methylotenera), sulfur-reducing bacterias (Hyphomicrobium), sulfur-oxidizing bacteria (Denitratisoma), iron-reducing bacteria (Romboutsia) and hydrolyzed bacterias (norank_f_norank_o_1–20 and norank_f_Caldilineaceae) coexisted in the ISPLAB system. Organics and iron sulfide drived the denitrification process in ISPLAB.

Co-production and enhancement of biogas and biohydrogen by optimizing NaOH-urera pretreatment conditions for kitchen waste

Kitchen waste (KW) constitutes a major portion of municipal solid waste, posing an imminent environmental challenge. Given its high water and organic content, KW is suitable for Anaerobic Digestion (AD) prior to its disposal, as it reduces Chemical Oxygen Demand (COD) and simultaneously generates biogas. The unique contribution of this study is the investigation of NaOH-urea pretreatment as a method to enhance AD of KW and sludge, ultimately leading to more efficient and environmentally friendly waste disposal. NaOH-urea pretreatment is selected for its ability to improve hydrolysis, increase organic matter solubilization, and enhance nutrient balance, ultimately boosting biogas yield during AD. Response surface methodology (RSM) was used for optimizing pretreatment conditions. AD experiments were performed batch-wise. For optimization, pretreatment time, temperature, and NaOH-urea concentration were selected as independent variables. RSM results indicated that optimum NaOH-urea concentration, time, and temperature conditions were 30 g/L, 30 min, and −5 °C, respectively. At optimum conditions, cumulative biogas was 316 ml, whereas biohydrogen % (v/v) was 36.21 %. Furthermore, the Modified Gompertz Model (MGM) and Logistic Function Model (LFM) were used to observe the efficacy of NaOH-urea pre-treatment of KW., The reaction kinetics were also discussed. Akaike's Information Criterion was employed to determine which model best fits the obtained experimental data. It was found that MGM is better than LFM for this study. Through experimental investigations and numerical modeling, this research provides insights into optimizing biogas and biohydrogen production from KW.

Occurrence and mobility of shale oil in the Jiyang Depression, eastern China

The occurrence of shale oil is important for its mobility and holds great significance in determining the available shale oil resources. Here, shale samples from three representative wells with different shale oil production levels in the Jiyang Depression, eastern China, were collected to evaluate the mobility of shale oil from its occurrence. The samples were subjected to Rock-Eval pyrolysis, X-ray diffraction, soluble organic matter, and N2 adsorption measurements. The results indicate that the shales in the high production well have higher contents of clay or felsic minerals, more apolar oil components, and smaller pore sizes than those in the low production well. In particular, the shale oil occurrence exhibits two stages involving pore surface adsorption followed by pore void filling, which are separated by a total organic carbon (TOC) content of 0.6 wt% OC (equivalent to 7.7 mg/gRock, the lower threshold of shale oil content for mobility). The corresponding threshold of pore diameter is 10 nm. By integrating the shale oil occurrence with the oil properties at the producing intervals, the following indices are proposed to evaluate the shale oil mobility and high production level: shale oil content greater than 0.6 wt% OC or 7.7 mg/gRock, oil saturation index greater than 100 mg/gTOC, apolarity index greater than 1, and pore diameter greater than 10 nm. Our work provides an index regime to evaluate the mobility and high production probability of shale oil, which will benefit the exploration and development of shale oil resources.

Maximizing resource recovery: Anaerobic digestion of residual biomass from essential oil extraction in four aromatic and medicinal plants

The valorization of organic waste through biomethanization presents a sustainable solution for energy production and waste management. In this study, the objective was to investigate the feasibility of anaerobic digestion for recovering extraction residues from essential oil extraction processes of Lavender, Peppermint, Eucalyptus, and Rosemary. Furthermore, the study aimed to evaluate the characteristics of the residual biomass by determining total organic matter and soluble organic matter using standardized protocols. The digestate obtained after anaerobic digestion was characterized for its physicochemical properties and its potential as an organic amendment. Statistical analysis was conducted to evaluate the results. The results demonstrate variations in these characteristics among different plant residues, with eucalyptus exhibiting lower VMO and higher BOD5 compared to other plants. The results of this study suggest promising potential for energy recovery from extraction residues, with an energy yield of up to 300 kWh/ton of waste. However, fermenting mixtures before anaerobic digestion is not recommended. In addition, the physicochemical characterization of the mixture resulting from the two mixtures MRH and MRF (DB digestate) highlights the potential of the digestate as an organic amendment. It also demonstrates the effectiveness of anaerobic digestion in reducing organic matter and enhancing the quality of the digestate. This contributes to sustainable waste management practices and boosts agricultural productivity. Morphological and elemental analyses provide insight into structural and compositional changes during biomethanization. Overall, this research highlights anaerobic digestion as a cost-effective approach to residual waste disposal in essential oil extraction industries. It supports circular economy principles by potentially generating revenue from energy production and organic amendments. This method offers a promising solution for waste recovery strategies in the transformation sector of aromatic and herbaceous plants for energy production.

Deciphering the reduction of antibiotic resistance genes (ARGs) during medium-chain fatty acids production from waste activated sludge: Driven by inhibition of ARGs transmission and shift of microbial community

Medium-chain fatty acids (MCFAs) production from waste activated sludge (WAS) by chain extension (CE) is a promising technology. However, the effects and mechanisms of CE process on the fate of antibiotic resistance genes (ARGs) remain unclear. In this study, the results showed that the removal efficiency of ARGs was 81.15 % in CE process, suggesting its efficacy in reducing environmental risks. Further, the observed decrease in mobile genetic elements (MGEs) indicated that CE process restricted the horizontal gene transfer (HGT). Complementing this, the increase in soluble organic matters and extracellular 16 S rDNA confirmed that MCFAs production caused bacterial damage. Decreased intracellular ARGs and increased extracellular ARGs further revealed that MCFAs production impaired ARGs hosts, thereby limiting the vertical gene transfer (VGT) of ARGs. Shift of microbial community combined with co-occurrence network analysis demonstrated that functional bacteria without host potential for ARGs were enriched, but potential ARGs and MGEs hosts decreased, showing the role of functional bacterial phylogeny and selection pressure of MCFAs in reducing ARGs. Finally, partial least squares path model was used to systematic verify the mechanism of ARGs removal in CE process, which was attributed to the inhibition of ARGs transmission (HGT and VGT) and shift of microbial community.

Evolution law of conductivity value in wet-end system of recycled pulp and its regulation strategy

The closed cycle of white water in the paper-making process is an important way to reduce material loss, water consumption, and wastewater discharge. However, how to improve the quality of white water and increase the efficiency of white water recycling is still a challenge. Faced with the increasing conductivity value of white water in the process of white water circulation, in this study, the factors affecting the conductivity value of white water for recycled pulp and the strategies for regulating the conductivity value were investigated by simulating the white water circulation during the paper-making process. The experimental results indicate the accumulation of inorganic salts is one of the reasons for the increasing conductivity value of white water. When inorganic salts accumulate to dynamic equilibrium, the increase amplitude of conductivity caused by inorganic salts does not exceed 5 % of the initial conductivity. Under the white water circulation, the polyelectrolytes formed by degradated starch are the main factor for the continuous increasing conductivity value of white water. The retention of starch, during the paper-making process, can be improved by adding in-situ generated aluminum hydroxide colloids and the polyelectrolytes from starch degradation in white water can also be adsorbed by aluminum hydroxide precipitates. The effects of soluble organic matter and dissolved inorganic matter on white water conductivity were revealed, and the formation pattern of conductivity value in the wet-end system of recycled pulp was derived. At the same time, methods for removing organic matter and polyelectrolytes were proposed. Both are helpful to improve the quality of white water for paper-making industry and reduce the pollution of the wastewater.

Indicative significance of the interfacial interactions between pore surface and soluble organic matter on the shale oil mobility

The exploration and exploitation of shale oil resources enhance the necessity to characterize the mobility of the occluded oil in shales. Up to now, the understanding of the controlling factors of shale oil mobility has mainly come from molecular dynamics simulation but lacking in-depth research on actual shales. Therefore, in this study, the effects of mineral composition, soluble organic matter (SOM) composition and wettability on the shale oil mobility were studied by X-ray diffraction, N2 adsorption, mercury intrusion, contact angle, chloroform bitumen and group component detection methods, comprehensively. The results show that: (1) The asphaltene contents and (Asphaltenes × Aromatics)/(Saturates × Resins) negatively and positively correlate with clay and carbonate mineral contents, respectively, while the I/S and illite contents present opposite trend with (Asphaltenes × Aromatics)/(Saturates × Resins). These correlations indicate that the SOM that confined in the pores constructed with carbonate minerals and illite present better flow potential. (2) Both δVt and δSSA negatively correlate with asphaltenes and (Asphaltenes × Aromatics)/(Saturates × Resins). That is, less pores and surfaces can be released by extraction for the shales with more asphaltenes. Therefore, it can be concluded that asphaltene is a negative factor for shale oil seepage. Additionally, the larger pores present better flow condition for shale oil, even for asphaltenes. (3) Pore surface wettability also significantly affects the shale oil mobility. The hydrophobicity of the pore wall greatly inhibits the shale oil flow, especially for the mesopores and macropores. The pattern diagram was established to illustrate the effect of the interactions between pore surfaces and shale oil components on the movable potential. Based on our research, mineral composition, group composition and pore surface wettability are efficient parameters for the shale oil mobility evaluation based on the interfacial interaction theory, and the “sweet spots” for shale oil seepage of the Jiyang Depression are the shales with more illite, carbonate, saturates and relatively low lipophilicity.

Nutrient dynamics in wetland systems associated with hydrological and anthropogenic variations in the south of Samborombón Bay, Argentina

Wetlands provide numerous ecosystem services to the environment, such as nutrient removal and storage. The aim of this work is to evaluate the nutrient dynamics in different sectors within wetland systems in the south of the Samborombón Bay (Argentina) based on hydrological and/or anthropogenic variations. For this purpose, the hydrological features of the wetland were defined through the analysis of satellite images, precipitation and tidal data, and field surveys. Three sectors were identified in the wetland: one with tidal influence, another which is dependent on rainfall, and another that receives inputs from rainfall and from a sewage effluent treatment plant. In order to analyze the nutrient dynamics, samples of surface water, groundwater, and sediments were collected from these sectors. Measurements of pH and electrical conductivity were determined in situ in water samples, while the concentration of inorganic forms of phosphorus and nitrogen, soluble reactive silica, and organic carbon were determined through laboratory analysis. Also, bioavailable phosphorus, organic matter, pH, and electrical conductivity were determined in the sediment samples collected. Statistical analysis of the data reveals differences between the sectors and allows the interpretation of the dynamics of the studied components in the wetland. Electrical conductivity distinguishes the intertidal sectors of the wetland while components associated with P and N discriminate the sectors with inputs from the sewage effluent treatment plant. On the other hand, soluble reactive silica, organic carbon, and organic matter do not seem to be influenced by the tide or effluent discharge. This study demonstrates that the studied wetland works as a nutrient retention area, providing ecosystem services to local inhabitants. Although these services can be utilized, they require a continuous monitoring over time to provide an early warning in case the variations in P and N cycles could lead to eutrophication or wetland degradation.

Behavior of organic matter and gold under conditions of folding deformations

He article provides a brief overview of publications on natural organic matter (OM) and its transformation at various stages of the sedimentary rocks conversion. It is demonstrated, that the changes in the composition, structure, and properties of OM were accompanied by changes in the concentration of metals, including gold. The OM and gold behavior under conditions of folding deformations was examined by the authors on the example of the formation of zones of intense folding in large gold-mining regions of Russia (Central Kolyma and Baikal-Patom). Plastic deformations of sedimentary rocks are associated with active migration of gold in the composition of soluble OM components. The squeezing and injection structures that arise during the folding ensured the natural multidirectional movement of OM of the lowest viscosity into the areas of decompaction of sedimentary rocks. This migration resulted in anomalous concentrations of gold and OM in the locking parts of the folds. This process was intensely manifested in the terrigenous-shale rock sequence within the Dekdekan zone of folded dislocations (Central Kolyma region), where gold-bitumen mineralization was identified, represented by a large lens-shaped deposit 500–800 × 2500 m in size. The only metal concentrator here is oil-like bitumen forming very fine dissemination in the rock.

The treatment of petrochemical wastewater via ozone-persulfate coupled catalytic oxidation: mechanism of removal of soluble organic matter.

Petrochemical wastewater contains a variety of organic pollutants. Advanced oxidation processes (AOPs) are used for deep petrochemical wastewater treatment with distinct advantages, including the complete mineralization of organic substances, minimal residual byproducts, and compatibility with biological treatment systems. This work evaluates the effectiveness of three methods, namely, ozone, persulfate, and O3-PMS (ozone-persulfate) processes, which were compared to remove soluble organic matter. The O3-PMS process offered significant advantages in terms of organic matter removal efficiency. This process involves ozone dissolution in an aqueous persulfate solution, producing a more significant amount of hydroxyl radicals in comparison to single AOPs. The production of hydroxyl radicals and the synergistic effect of hydroxyl radicals and persulfate radicals were investigated. In the O3-PMS process, transition metal ions were added to understand the mechanism of the O3-PMS coupled catalytic oxidation system. The results showed that when the ozone concentration was in the range of 5 ~ 25mg/L, the dosage of persulfate was in the range of 0.01 ~ 0.05mol/L, the dosage of metal compounds was in the range of 0:0 ~ 2:1, and the reaction time was in the range of 0 ~ 2h; the optimum chemical oxygen demand (CODCr) and total organic content (TOC) removal effect was achieved under the coupled system with an ozone concentration of 10mg/L, a persulfate dosage of 0.02mol/L, a 1:2 dosage ratio of between Fe2+ and Cu2+ compounds, and a reaction time of 2h. Under optimal reaction conditions, the rates of CODCr and TOC removal reached 70% and 79.3%, respectively. Furthermore, the removal kinetics of the O3-PMS coupled catalytic oxidation system was analyzed to optimize the removal conditions of COD and TOC, and the mechanism regulating the degradation of dissolved organic matter was explored by three-dimensional fluorescence and GC-MS technology. Thus, O3-PMS coupled catalytic oxidation is an effective process for the deep treatment of wastewater. The careful selection of transition metal ions serves as a theoretical foundation for the subsequent preparation of catalysts for the ozone persulfate oxidation system, and this study provides a suitable reference for removing organic matter from petrochemical wastewater.

Retention time and organic loading rate as anaerobic co-digestion key-factors for better digestate valorization practices: C and N dynamics in soils

The growing use of anaerobic co-digestion (AcoD) in processing organic waste has led to a significant digestate production. To effectively recycle digestate back into soils, it is crucial to understand how operational variables in the AcoD process influence the conversion of organic matter (OM). To address this, a combination of biochemical fractionation and various soil incubation tests were employed to assess the stability of OM in digestates generated from anaerobic continuous reactors fed with a food waste-hay mixture and operating at different hydraulic retention times (HRT) and organic loading rates (OLR). This study revealed that digester performance and operating parameters impacted carbon dynamics in soils. A decrease in the carbon mineralization in soils when increasing the HRT was reported (48 ± 4 % for 70 days compared to 59 ± 1 % for 42 days). Specific HRT and OLR values were found to be linked to carbon accessibility and complexity, confirming that longer HRT lead to higher OM removal and increased complexity in soluble OM, despite minor discrepancies in relative carbon distribution. Furthermore, comparable rates of nitrogen mineralization in soils were observed for all digestates, consistent with the accessibility of nitrogen from the particulate OM. Nevertheless, AcoD converted substrates with the potential to immobilize nitrogen in soils into fast-acting fertilizers. In summary, this study underscores the importance of controlling the AcoD performances to evaluate the suitability of digestates for sustainable agricultural practices.

Analysis of the correlation between mechanical and physicochemical properties of particles based on a diesel oxidation catalytic system

The mechanical and physicochemical properties of diesel engine exhaust particles before and after diesel oxidation catalyst (DOC) treatment are analyzed. It is considered important to explore the interrelationships between these attributes in order to understand their relevance. Understanding of these properties provides insights into the deposition characteristics of particles within the system and the evolution of the particles after the DOC treatment, which may help the selection of appropriate aftertreatment strategies. In this paper, particle samples were collected before and after the DOC to explore the variations in the mechanical and physicochemical properties of the particles under different operating conditions. Atomic force microscopy, thermogravimetric analysis, transmission electron microscopy, and Raman spectroscopy were employed to investigate the attraction force, adhesion force, adhesion energy, oxidative reactivity, primary particle size, nanostructure, and graphitization degree of the particles. The results indicated that under post-injection conditions, the attraction force, adhesion force, and adhesion energy of the particles increased significantly. However, when the particles passed through the DOC, these properties decreased to varying degrees. By analyzing the combination of physicochemical properties, it was determined that the attraction force of the particles was primarily influenced by the primary particle size and the particle's graphite structure. The adhesion force was found to be closely related to the content of soluble organic matter. Additionally, the soluble organic matter affected the degree of particle agglomeration by altering the adhesion energy of the particles.

Heavy metal and soluble organic matter removal using natural conglomerate and siltstone soils: Towards soil aquifer treatment for oily wastewater

The present work aims to assess the viability of vadose zone siltstone and conglomerate for oil and gas-produced water (PW) treatment using soil aquifer treatment (SAT). Comprehensive batch adsorption tests were carried out to analyze siltstone and conglomerate removal capacity for dissolved organics (phenol), and heavy metal ions (Ni 2+, and Zn 2+). The results demonstrated that conglomerate displayed a 98% removal capacity for Zn 2+ and 88% for Ni2+ while siltstone showed 82% removal for Zn2+ and 88% removal for Ni 2+. However, both siltstone and conglomerate showed low phenol removal (32% for siltstone, and 9% for conglomerate). The equilibrium adsorption isotherms were fitted by several adsorption models. The Langmuir model exhibited the best fitting for the adsorptions of phenol, Ni 2+ ions, and Zn 2+ ions on the two soils. The kinetics studies have revealed that phenol, Ni 2+ ions, and Zn 2+ ions adsorption on the two soil samples obey a pseudo-second-order kinetic model. Furthermore, Fourier transform infrared spectroscopy studies revealed that the Si-O peak in the soil plays a predominant role in interactions with heavy metal ions and phenol due to its high content in the soils. However, the electrostatic interactions between functional groups (Si-O, CO32-, and CO carbonyl groups) of the soil samples and the Ni2+ ions, Zn2+ ions, and phenol also contributed to the removal capacity. It is revealed that Zn2+ has a greater affinity for carboxyl groups than Ni2+. The obtained data in this study would support the effective design of SAT treatment for PW and help in reducing the risk of contaminating the groundwater aquifer.

Chemical and Geological Properties of Shale Gas: In Situ Desorption of Lower Cambrian Niutitang Shale in the Micangshan Tectonic Zone of South Shaanxi, China.

Shale gas was recently found in the Lower Cambrian Niutitang Formation (LCNF) of the Micangshan tectonic zone of south Shaanxi (MTZSS), but not in commercial quantities. To determine the laws governing the generation, enrichment, and desorption of shale gases in overmatured shale strata in the LCNF of MTZSS, we carried out in situ desorption experiments on nine shale core samples and got 168 desorbed gas samples at different phases of desorption. Also measured were the chemical and carbon isotopic compositions of these desorbed gas samples and the geochemical parameters of the shale core samples. CH4 was the predominant hydrocarbon shale gas identified in the 82.06-98.48% range, suggesting that the gases were mainly dry. The nonhydrocarbon gases found were CO2 and H2. The CH4 content of the desorbed gas samples dropped continuously during desorption, lowering the dryness index to 98.48 and 92.26% of the first and last desorbed shale gas, respectively. The change in the gas ratio during shale gas desorption proved that the adsorbability of the LCNF to the various gases follows the trend H2 > CO2 > C2H6 > CH4 > He. Further, δ13C2H6 and δ13CH4 become heavier during desorption, showing isotopic fractionation arising from the desorption-diffusion coeffect. As the desorption temperature increases, the value of δ13CH4 increases because 12CH4 is more sensitive to temperature than 13CH4, so it is with the ethane. Similar to the LCNF shale gas in other areas of China, the desorbed shale gases are characteristic of carbon isotope reversal (CIR) (δ13CH4 > δ13C2H6). The cracking of the residual soluble organic matter at the high overmaturity stage mixed with the cracking of kerogen at the early stage of maturation, causing CIR. Furthermore, the desorbed gas content was proportionally and inversely related to the CIR degree and final dryness index of the desorbed gas, respectively. Moreover, the carbon isotope fractionation degree of CH4 and δ13C1 of the last desorbed gas correlated positively with the desorbed gas content and the desorbed time of the gas. In conclusion, the four parameters are effective parameters for identifying shale gas sweet spots.

Peroxydisulfate activation and versatility of defective Fe3O4@MOF-808 for enhanced carbon and phosphorus recovery from sludge anaerobic fermentation

Although being viewed as a promising technology for reclamation of carbon and phosphorus from excess sludge, anaerobic fermentation (AF) grapples with issues such as a low yield of volatile fatty acids (VFAs) and high phosphorus recovery costs. In this study, we synthesized Fe3O4@MOF-808 (FeM) with abundant defects and employed it to simultaneously enhance VFAs and phosphorus recovery during sludge anaerobic fermentation. Through pre-oxidization of sludge catalyzed by FeM-induced peroxydisulfate, the soluble organic matter increased by 2.54 times, thus providing ample substrate for VFAs production. Subsequent AF revealed a remarkable 732.73 % increase in VFAs and a 1592.95 % increase in phosphate. Factors contributing to the high VFAs yield include the non-biological catalysis of unsaturated Zr active sites in defective FeM, enhancing protein hydrolysis, and the inhibition of methanogenesis due to electron competition arising from the transformation between Fe(III) and Fe(II) under Zr influence. Remarkably, FeM exhibited an adsorption capacity of up to 92.64 % for dissolved phosphate through ligand exchange and electrostatic attractions. Furthermore, FeM demonstrated magnetic separation capability from the fermentation broth, coupled with excellent stability and reusability in both catalysis and adsorption processes.

Analysis of landfill leachate promoting efficient application of weathered coal anaerobic fermentation

This research aimed to develop a new method for clean utilization and treatment of landfill leachate and solid waste weathered coal. Landfill leachate and weathered coal were adopted for combined anaerobic fermentation for methane production. The characteristics of microbial community, mechanism of biological methane production, and utilization characteristics of fermentation broth and solid residue for co-fermentation were analyzed through metagenomics, soluble organic matter detection and thermogravimetric (TG) analysis. The obtained results revealed that combined anaerobic fermentation increased methane production by 80.1%. Syntrophomonas, Salipiger, Methanosaeta and Methanothrix were highly correlated. Gene abundances of 2-oxoacid ferredoxin oxidoreductase and enolase were increased in methane conversion pathway mainly by acetic acid. Pyruvate-ferroredoxin oxidoreductase, 2-oxoglutarate synthase and succinate dehydrogenase acetate synthase intensified electron transfer pathways among microorganisms. Fulvic acid, tyrosine and tryptophan contents were high in fermentation broth. Volatile decomposition temperature, ignition point and residual char combustion temperature of residual coal were decreased and combustion was more stable. The obtained results showed that the co-fermentation of landfill leachate and weathered coal improved biological methane gas production, degraded weathered coal and improved combustion performance, which provided a new idea for weathered coal clean utilization.