Solar-enhanced lithium extraction with self-sustaining water recycling from salt-lake brines.

Lithium is an emerging strategic resource for modern energy transformation toward electrification and decarbonization. However, current mainstream direct lithium extraction technology via adsorption suffers from sluggish kinetics and intensive water usage, especially in arid/semiarid and cold salt-lake regions (natural land brines). Herein, an efficient proof-of-concept integrated solar microevaporator system is developed to realize synergetic solar-enhanced lithium recovery and water footprint management from hypersaline salt-lake brines. The 98% solar energy harvesting efficiency of the solar microevaporator system, elevating its local temperature, greatly promotes the endothermic Li+ extraction process and solar steam generation. Benefiting from the photothermal effect, enhanced water flux, and enriched local Li+ supply in nanoconfined space, a double-enhanced Li+ recovery capacity was delivered (increase from 12.4 to 28.7 mg g-1) under one sun, and adsorption kinetics rate (saturated within 6 h) also reached twice of that at 280 K (salt-lake temperature). Additionally, the self-assembly rotation feature endows the microevaporator system with distinct self-cleaning desalination ability, achieving near 100% water recovery from hypersaline brines for further self-sufficient Li+ elution. Outdoor comprehensive solar-powered experiment verified the feasibility of basically stable lithium recovery ability (>8 mg g-1) directly from natural hypersaline salt-lake brines with self-sustaining water recycling for Li+ elution (440 m3 water recovery per ton Li2CO3). This work offers an integrated solution for sustainable lithium recovery with near zero water/carbon consumption toward carbon neutrality.

Core-Shell MnFe Nanocatalyst Derived from Prussian Blue Analogs for Peroxymonosulfate Activation: Nonradical Mechanism and Bimetallic Valence Cycle.

Sulfamethazine (SAT) is widely present in sediment, soil, rivers, and groundwater. Unfortunately, traditional water treatment technologies are inefficient at eliminating SAT from contaminated water. Therefore, developing an effective and ecologically friendly treatment procedure to effectively remove SAT is critical. This has raised concerns about its potential impact on the environment and human health. In this study, metal-organic-inorganic composites consisting of graphene-encapsulated Fe-Mn metal catalyst (Mn3Fe1-NC) were synthesized by calcining MnFe Prussian blue analogs (PBA) under a nitrogen atmosphere. The composites were applied to activate peroxymonosulfate (PMS) and facilitate the degradation of SAT in aquatic environments. The Mn3Fe1-NC, dosed with 5 mg, in combination with PMS, dosed with 1.5 mmol L-1, achieved a 91.8% degradation efficiency of SAT. The transformation of the CN skeleton led to the formation of a carbon shell structure, which consequently reduced metal ion leaching from the material. At various pH levels, the iron and manganese ions were observed to leach out at levels lower than 0.1392 and 0.0580 mg L-1, respectively. In contrast, the Mn3Fe1-NC was found to be minimally impacted by pH levels and coexisting ions present in the aqueous environment. Radical burst experiments and electrochemical analysis tests verified that degradation primarily occurs through the nonradical pathway of electron transfer. The active sites responsible for this process were identified as the Mn (IV) and graphitic-N atoms on the material, which facilitate direct electron transfer. Additionally, the presence of Fe atoms promotes the valence cycling of Mn atoms. This study introduces new insights into the reaction mechanism and the constitutive relationship of catalytic centers in nonradical oxidation reactions.

Transport of per-/polyfluoroalkyl substances from leachate to groundwater as affected by dissolved organic matter in landfills.

The transport of per- and polyfluoroalkyl substances (PFAS) from landfill leachate to surrounding soil and groundwater poses a threat to human health via the food chain or drinking water. Studies have shown that the transport process of PFAS from the solid to liquid phase in the environment is significantly affected by dissolved organic matter (DOM) adsorption. However, the mechanism of PFAS release from landfill solids into leachate and its transport to the surrounding groundwater remains unclear. In this study, we identified the composition of PFAS and DOM components and analyzed the association between DOM components, physicochemical factors, and PFAS concentrations in landfill leachate and groundwater. This study demonstrated that the frequency of PFAS detection in the samples was 100%, and the PFAS concentrations in leachate were greater than in the groundwater samples. Physicochemical factors, such as ammonium-nitrogen (NH4+-N), sodium (Na), calcium (Ca), DOM components C4 (macromolecular humic acid), SUVA254 (aromatic component content), and A240-400 (humification degree and molecular weight), were strongly correlated with PFAS concentrations. In conclusion, PFAS environmental risk management should be enhanced in landfills, especially in closed landfills, or landfills that are scheduled to close in the near future.

Synergistic removal of total petroleum hydrocarbons and antibiotic resistance genes in Yellow River Delta wetlands contaminated soil composting regulated by biogas slurry addition.

The interactive effects between the emerging contaminant antibiotic resistance genes (ARGs) and the traditional pollutant total petroleum hydrocarbons (TPHs) in contaminated soils remain unclear. The synergistic removal of TPHs and ARGs from composted contaminated soil, along with the microbial mechanisms driven by the addition of biogas slurry, have not yet been investigated. This study explored the impact of biogas slurry on the synergistic degradation mechanisms and bacterial community dynamics of ARGs and TPHs in compost derived from contaminated soil. The addition of biogas slurry resulted in a reduction of targeted ARGs and mobile genetic elements (MGEs) by 9.96%-95.70% and 13.32%-97.66%, respectively. Biogas slurry changed the succession of bacterial communities during composting, thereby reducing the transmission risk of ARGs. Pseudomonas, Cellvibrio, and Devosia were identified as core microorganisms in the synergistic degradation of ARGs and TPHs. According to the partial least squares path model, temperature and NO3- indirectly influenced the removal of ARGs and TPHs by directly regulating the abundance and composition of host microbes and MGEs. In summary, the results of this study contribute to the high-value utilization of biogas slurry and provide methodological support for the low-cost remediation of contaminated soils.

Contribution of sulfur-containing precursors to release of hydrogen sulfide in sludge composting.

Hydrogen sulfide (H2S) production during composting can impact the environment and human health. Especially during the thermophilic phase, H2S is discharged in large quantities. However, in sludge composting, the contributions of different sulfur-containing precursors to H2S fluxes, key functional microorganisms, and key environmental parameters for reducing H2S flux remain unclear. Analysis of cysteine (Cys), methionine (Met), and sulfate (SO42-) concentrations, multiple stepwise regression analysis, and Kyoto Encyclopedia of Genes and Genomes (KEGG) annotation analysis of metagenomes showed that Cys was the main contributor to the production of H2S and that Met was among the main sources during the first three days of composting, while the SO42- contribution to H2S was negligible. Fifteen functional genera involved in the conversion of precursors to H2S were identified by co-occurrence network analysis. Only Bacillus showed high temperature resistance (>50 °C) and the ability to reduce H2S. Redundancy analysis showed that total carbon (64.0 %) and pH (23.3 %) had significant effects on functional bacteria. H2S had a quadratic relationship with sulfur-containing precursors. All microbial network sulfur-containing precursors metabolism modules showed a highly significant relationship with Cys.

Bioindicator responses to extreme conditions: Insights into pH and bioavailable metals under acidic metal environments.

Acid mine drainage (AMD) caused environmental risks from heavy metal pollution, requiring treatment methods such as chemical precipitation and biological treatment. Monitoring and adapting treatment processes was crucial for success, but cost-effective pollution monitoring methods were lacking. Using bioindicators measured through 16S rRNA was a promising method to assess environmental pollution. This study evaluated the effects of AMD on ecological health using the ecological risk index (RI) and the Risk Assessment Code (RAC) indices. Additionally, we also examined how acidic metal stress affected the diversity of bacteria and fungi, as well as their networks. Bioindicators were identified using linear discriminant analysis effect size (LEfSe), Partial least squares regression (PLS-R), and Spearman analyses. The study found that Cd, Cu, Pb, and As pose potential ecological risks in that order. Fungal diversity decreased by 44.88% in AMD-affected areas, more than the 33.61% decrease in bacterial diversity. Microbial diversity was positively correlated with pH (r = 0.88, p = 0.04) and negatively correlated with bioavailable metal concentrations (r = -0.59, p = 0.05). Similarly, microbial diversity was negatively correlated with bioavailable metal concentrations (bio_Cu, bio_Pb, bio_Cd) (r = 0.79, p = 0.03). Acidiferrobacter and Thermoplasmataceae were prevalent in acidic metal environments, while Puia and Chitinophagaceae were identified as biomarker species in the control area (LDA>4). Acidiferrobacter and Thermoplasmataceae were found to be pH-tolerant bioindicators with high reliability (r = 1, P < 0.05, BW > 0.1) through PLS-R and Spearman analysis. Conversely, Puia and Chitinophagaceae were pH-sensitive bioindicators, while Teratosphaeriaceae was a potential bioindicator for Cu-Zn-Cd metal pollution. This study identified bioindicator species for acid and metal pollution in AMD habitats. This study outlined the focus of biological monitoring in AMD acidic stress environments, including extreme pH, heavy metal pollutants, and indicator species. It also provided essential information for heavy metal bioremediation, such as the role of omics and the effects of organic matter on metal bioavailability.

Upgrade from aerated static pile to agitated bed systems promotes lignocellulose degradation in large-scale composting through enhanced microbial functional diversity.

Composting presents a viable management solution for lignocellulose-rich municipal solid waste. However, our understanding about the microbial metabolic mechanisms involved in the biodegradation of lignocellulose, particularly in industrial-scale composting plants, remains limited. This study employed metaproteomics to compare the impact of upgrading from aerated static pile (ASP) to agitated bed (AB) systems on physicochemical parameters, lignocellulose biodegradation, and microbial metabolic pathways during large-scale biowaste composting process, marking the first investigation of its kind. The degradation rates of lignocellulose including cellulose, hemicellulose, and lignin were significantly higher in AB (8.21%-32.54%, 10.21%-39.41%, and 6.21%-26.78%) than those (5.72%-23.15%, 7.01%-33.26%, and 4.79%-19.76%) in ASP at three thermal stages, respectively. The AB system in comparison to ASP increased the carbohydrate-active enzymes (CAZymes) abundance and production of the three essential enzymes required for lignocellulose decomposition involving a mixture of bacteria and fungi (i.e., Actinobacteria, Bacilli, Sordariomycetes and Eurotiomycetes). Conversely, ASP primarily produced exoglucanase and ß-glucosidase via fungi (i.e., Ascomycota). Moreover, AB effectively mitigated microbial stress caused by acetic acid accumulation by regulating the key enzymes involved in acetate conversion, including acetyl-coenzyme A synthetase and acetate kinase. Overall, the AB upgraded from ASP facilitated the lignocellulose degradation and fostered more diverse functional microbial communities in large-scale composting. Our findings offer a valuable scientific basis to guide the engineering feasibility and environmental sustainability for large-scale industrial composting plants for treating lignocellulose-rich waste. These findings have important implications for establishing green sustainable development models (e.g., a circular economy based on material recovery) and for achieving sustainable development goals.

Linking Redox Characteristics to Dissolved Organic Matter Derived from Different Biowaste Composts: A Theoretical Modeling Approach Based on FT-ICR MS Analysis.

Compost dissolved organic matter (DOM) is a complex mixture of redox-active organic molecules that impact various biogeochemical processes in soil environments. However, the impact of chemical complexity (heterogeneity and chemodiversity) on the electron accepting capacity (EAC) and electron donating capacity (EDC) of DOM molecules remains unclear, which hinders our ability to predict their environmental behavior and redox properties. In this study, the applicability of Vienna Soil Organic Matter Modeler 2 (VSOMM2) to the composting system based on the FT-ICR MS data has been validated. A molecular modeling approach using VSOMM2 and Schrödinger software was developed to quantitatively assess the redox sites and molecular interactions of compost DOM. Compost DOM molecules are categorized into three distinct groups based on their heterogeneous origins. In addition, we have developed 18 molecular models of compost DOM based on the links of molecules to EAC/EDC. Finally, Ar-OH, quinone, Ar-SH, and Ar-NH2 were identified as the redox sites; noncovalent contacts, H bonds, salt bridges, and aromatic-H bonds might be significant electronic transmission channels of compost DOM. Our findings contribute to the development of precise regulatory methods for functional molecules within compost DOM, providing the fine standards for composts matching specific ecosystem service requirements.

Revisiting the biological pathway for methanogenesis in landfill from metagenomic perspective-A case study of county-level sanitary landfill of domestic waste in North China plain.

Landfill is the third highest contributor to anthropogenic methane (CH4) emissions, produced primarily by the anaerobic decomposition of organic matter by microbes. However, how various microbial metabolic processes contribute to CH4 production in domestic waste landfill remains elusive. We addressed this problem by investigating the methanogenic communities, methanogenic functional genes, KEGG modules and KEGG pathways in a county-level MSW sanitary landfill in North China Plain, China. Results showed that Methanomicrobiales, Methanobacteriales, Methanosarcinales, Micrococcales, Corynebacteriales and Bacillales were the dominant methanogens. M00357, M00346, M00567 and M00563 were the four major methane metabolic modules. The most abundant genes were ACSS, ackA and fwd with the relative abundance of 19.26-54.54%, 6.14-25.78% and 6.76-16.51%, respectively. The two essential genes of methanogenesis were detected with the relative abundance of 2.66-9.58% (mtr) and 1.63-9.14% (mcr). These findings indicated that acetotrophic and hydrogenotrophic methanogenesis were the major pathways. Methanomicrobiales, Methanosarcinales and Clostridiales were the key microbes to these pathways identified by co-occurrence network. Analysis of relative contribution of species to function further showed that Micrococcales, Corynebacteriales and Bacillales were special contributors to acetotrophic methanogenesis pathway. Redundancy analysis revealed that above functional genes and microbes were mainly controlled by NH4+ and pH. Our results can help to provide develop the fine management strategies for methane utilization and emission reduction in landfill.

Insight into the fate of metal ions in response to the refined classification and transformation order of dissolved organic matter components during municipal solid waste composting.

The refined classification and subtle transformation order of dissolved organic matter (DOM) components may govern the fate of metal ions (MIs) during composting. However, the classification of DOM components is still rough and the fate of MIs in response to the refined transformation order of DOM during municipal solid waste composting (MSWC) has not been studied. Here, the refined classification and evolution order of DOM components were redefined by two-dimensional correlation spectroscopy (2DCOS) analysis. Eight DOM components were redefined and their evolution order was: tyrosine-like (peak B)>humic acid-like (peak C1>peak C2)>terrestrial humic-like with small molecular size (peak A)>UVA humic-like with medium molecular size (peak D2)>UVC humic-like with medium molecular size (peak D1)>UVA humic-like with large molecular size (peak E2)>UVC humic-like with large molecular size (peak E1). Na and As were releasing in the whole process of DOM transformation. Cu and Al showed strong affinity with humic-like fraction, the anabolism of which leading to storage of Cu and Al in compost. Si, Fe, Mn, Co, Zn, Ni, Sr, Mg and Cr tend to combine with humic-like fraction with small molecular size. These responses were influenced by synergistic effect of key microorganisms (two bacterial groups and three fungal groups), in which the contribution of bacteria was greater than fungus. Finally, partial least-square path models of "environmental factors-key microorganisms-transformation order of DOM-MIs" were constructed. The combination of humic-like fractions continuously produced during MSWC and MIs made compost product with potential environmental risks. It is of great significance to develop abiotic factors regulation approach based on refined classification and transformation of organic components for reducing environmental risks of compost product.

A critical review of the occurrence, fate and treatment of per- and polyfluoroalkyl substances (PFASs) in landfills.

The aim of this critical review is i) to summarize the occurrence of Per- and polyfluoroalkyl substances (PFASs) in landfills; ii) to outline the environmental fate and transport of PFASs in landfills; iii) to compare the treatment technologies of PFASs in landfill leachate and remediation methods of PFASs in surrounding groundwater; iv) to identify the research gaps and suggest future research directions. In recent years, PFASs have been detected in landfills around the world, among which Perfluoroalkyl acids (PFAAs) especially Perfluorooctanoic acid (PFOA) and Perfluorooctane sulfonic acid (PFOS) are mostly studied due to their long-term stability. Short-chain PFASs (<8 carbons) are more common than long-chain PFASs (≧8 carbons) in landfill leachate. PFASs in landfill leachate are eventually transported to the surrounding groundwater, surface water and soil. Some PFASs evaporate from landfills to the ambient air. To avoid the environmental and health risks of PFASs in landfills, new technologies and combined use of existing technologies have been implemented to treat PFASs in landfill leachate. Integrated remediation methods are applied to control the diffusion of PFASs in groundwater surrounding landfills. In future, the mechanisms of PFAAs precursors degradation, the correlation among PFASs in different environmental media around landfills, as well as the environmental behavior and toxic effect of combined pollutants together with PFASs in landfill leachate and surrounding groundwater should be studied.

Insights into relationships between polycyclic aromatic hydrocarbon concentration, bacterial communities and organic matter composition in coal gangue site.

Coal mining usually brought polycyclic aromatic hydrocarbons (PAHs) contamination. Relationships between the concentration of PAHs, bacterial communities and soil environmental factors were important for bioremediation of PAHs in soil. Total 4 kinds of soil samples with different concentrations of PAHs were selected from 7 typical coal gangue（CG） sites in Huainan, Anhui Province. The relationships between microorganisms, dissolved organic matter (DOM) composition and PAHs concentration were systematically analyzed in this work. Total 11 kinds of PAHs were enriched in the soil surface layer. That was attributed to the strong binding of soil organic matter (SOM) to PAHs. PAHs contamination reduced the diversity of soil microbial. The abundance of PAHs-degrading genera such as Arthrobacter decreased with the increasing concentration of PAHs. Mycobacterium increased with the increasing concentration of PAHs in all samples. The microbial activities decreased with increasing concentration of PAHs. The increasing contents of LWM-PAHs and DOM were beneficial to improve the activities of soil microbial. The increasing DOM aromaticity was beneficial to improve the bioavailability of PAHs according to the correlation analysis between PAHs content and DOM structural parameters. The obtained results provide a basis for better understanding the contamination characteristics and microbial communities of coal gangue PAH-contaminated sites.

Specific response of soil properties to microplastics pollution: A review.

The soil environment is a critical component of the global ecosystem and is essential for nutrient cycling and energy flow. Various physical, chemical, and biological processes occur in the soil and are affected by environmental factors. Soil is vulnerable to pollutants, especially emerging pollutants, such as microplastics (MPs). MPs pollution has become a significant environmental problem, and its harm to human health and the environment cannot be underestimated. However, most studies on MPs pollution have focused on marine ecosystems, estuaries, lakes, rivers, and other aquatic environments, whereas few considered the effects and hazards of MPs pollution of the soil, especially the responses of different environmental factors to MPs. In addition, when many MPs pollutants produced by agricultural activities (mulching film, organic fertilizer) and atmospheric sedimentation enter the soil environment, it will cause changes in soil pH, organic matter composition, microbial community, enzyme activity, animals and plants and other environmental factors. However, due to the complex and changeable soil environment, the heterogeneity is very strong. The changes of environmental factors may react on the migration, transformation and degradation of MPs, and there are synergistic or antagonistic interactions among different factors. Therefore, it is very important to analyze the specific effects of MPs pollution on soil properties to clarify the environmental behavior and effects of MPs. This review focuses on the source, formation, and influencing factors of MPs pollution in soil and summarizes its effect and influence degree on various soil environmental factors. The results provide research suggestions and theoretical support for preventing or controlling MPs soil pollution.

Mechanisms and biological effects of organic amendments on mercury speciation in soil-rice systems: A review.

Mercury (Hg) pollution is a well-recognized global environmental and health issue and exhibits distinctive persistence, neurotoxicity, bioaccumulation, and biomagnification effects. As the largest global Hg reservoir, the Hg cumulatively stored in soils has reached as high as 250-1000 Gg. Even more concerning is that global soil-rice systems distributed in many countries have become central to the global Hg cycle because they are both a major food source for more than 3 billion people worldwide and the central bridge linking atmospheric and soil Hg circulation. In this review, we discuss the form distribution, transformation, and bioavailability of Hg in soil-rice systems by focusing on the Hg methylation and demethylation pathways and distribution, uptake, and accumulation in rice plants and the effects of Hg on the community structure and ecological functions of microorganisms in soil-rice systems. In addition, we clarify the mechanisms through which commonly used humus and biochar organic amendments influence Hg and its environmental effects in soil-rice systems. The review also elaborates on the advantages of sulfur-modified biochars and their critical role in controlling Hg migration and bioavailability in soils. Finally, we provide key information about Hg pollution in soil-rice systems, which is of great significance for developing appropriate strategies and mitigation planning to limit Hg bioconcentration in rice crops and achieving key global sustainable development goals, such as the guarantee of food security and the promotion of sustainable agriculture.

The key role of denitrification and dissimilatory nitrate reduction in nitrogen pollution along vertical landfill profiles from metagenomic perspective.

Landfill are persistent sources of nitrogen (N) pollution even in the decades after closure. However, the biological pathways of N-pollution, particularly N2O and NH4+, at different landfill depths have received little attention. In this study, metagenomic analysis was conducted on landfill refuse from vertical reservoir profiles in two closed landfills named XT and MT. NH4+ concentrations were found to be higher in deeper layers of MT, while greater potential for N2O emissions occurred in XT and the shallow layers of MT. Furthermore, the community structure and function of N-metabolizing microbes were more strongly defined by landfill depth than landfill type. Denitrification, involving abundant nirK and norB genes, was identified as the major pathway for N2O production in both XT and MT-shallow, while dissimilatory nitrate reduction with abundant nirBD genes was identified as the major pathway for NH4+ accumulation. Microbes of norB-type and nirBD-type were positively affected by NO3- in XT, whereas negatively affected by contents of organic material and moisture in MT-shallow. The mechanism by which nitrogen fixation, with abundant nifH genes, contributes to NH4+ accumulation in MT-deep should be further elucidated. These findings can provide a theoretical basis for governing scientific N-pollution control strategies throughout the entire landfill process.

Environmental risk of tailings pond leachate pollution: Traceable strategy for leakage channel and influence range of leachate.

Identifying the leakage channel and the influencing range is essential for controlling the environmental risks of leachate from the tailings pond. The investigation of leachate pollution in tailings pond has the defect of focusing only on the scope of tailings pond in recent studies. This study innovatively built a comprehensive investigation and accurate verification system for leachate leakage of tailings pond integrated with the aeromagnetic survey, ground penetrating radar, hydrochemistry and isotope coupling methods. Geophysical exploration found that among the four fault zones, and the F1 was the channel for leachate to recharge the groundwater 2.53 km away from the tailings pond. The fissures inside the tailings pond were connected with the natural fissures outside, forming a leachate migration channel. The hydrochemistry and isotope characteristics showed that the groundwater far away from the tailings pond were polluted by arsenic containing leachate, which verified the geophysical exploration results. The significant correlation between arsenic and SO2-4 concentration indicated that arsenic in leachate originated from the oxidation release of sulfide minerals (i.e., arsenopyrite). This study sheds light on the comprehensive investigation of leachate leakage in the tailings pond. This development method also provides guidance for environmental risk identification of other contaminated sites.

Long-term application of nitrogen fertilizer alters the properties of dissolved soil organic matter and increases the accumulation of polycyclic aromatic hydrocarbons.

Soil is a key component of terrestrial ecosystems, as it provides nutrients and energy for all terrestrial organisms and is the site of various physical, chemical, and biological processes. Soil organic matter is particularly important for the role that it plays in element cycling, as well as the adsorption and degradation of soil pollutants. Nitrogen (N) fertilizer is an important nutrient element in the soil microenvironment. Applications of N fertilizer can improve soil quality, but the long-term excessive application of N fertilizer can lead to the deterioration of the soil environment, alter the properties of organic matter, and affect the adsorption and accumulation of soil pollutants. In recent years, several pollutants, especially polycyclic aromatic hydrocarbons (PAHs), have accumulated in farmland soil due to long-term sewage irrigation. However, few studies have examined the response of soil PAHs accumulation to long-term N application, as well as the relationship between this response and changes in soil microenvironmental indicators caused by N application. Here, we conducted field experiments to study changes in soil pH, total organic carbon, and dissolved organic matter (DOM) under long-term N application, as well as their effects on PAHs accumulation. The application of N fertilizer resulted in the aromatization and humification of soil DOM, enhanced the accumulation response ratio (-0.05-0.32) and the amount of PAHs accumulated in soil (more than 30%), and exacerbated the environmental risks of PAHs. Our findings provide new insights that could aid the management and control of PAHs pollution of soil in sewage-irrigated areas.

A novel process for food waste recycling: A hydrophobic liquid mulching film preparation.

Appropriate and effective recycling of food waste (FW) has become increasingly significant with the promotion of garbage classification in China. In this study, a novel and green process was developed to recycle FW to prepare a biodegradable composite liquid mulching film (LMF) through crosslinking with sodium alginate (SA). The solid phase of FW was obtained as the raw material after hydrothermal pretreatment to remove pathogens and salts, and to improve the reactivity of active components at a moderate temperature. The prepared LMF had a hydrophobic surface and compact structure due to the lipid in FW and the acetalization reaction and hydrogen bonds among SA, glutaraldehyde and multi-active components of FW, resulting in enhanced water vapor barrier properties. The minimum water vapor permeability of the prepared LMF reached (8.23 ± 0.05) ✕ 10-12 g cm/(cm2·s·Pa) with 1.82 wt % of plasticizer, 0.74 wt% of crosslinker and a mass ratio of HTP-FW to SA of 3.56:1. The prepared LMF showed good mechanical properties and could maintain its integrity after spraying it on the soil surface for 31 days. In addition, it could effectively prevent the loss of soil moisture and heat, promote the seed germination of Chinese cabbage and achieve 89.14% of weight loss after burying in the soil for 27 days. This study provides a high value-added route to convert the FW to a hydrophobic LMF with superior properties, which addresses not only the problem of food waste but also the pollution of plastic mulching film.

Responses of bacterial taxonomic attributes to mercury species in rhizosphere paddy soil under natural sulphur-rich biochar amendment.

Biochar and sulphur (S) are important factors regulating the level, speciation and transformation of mercury (Hg), leading to alterations in the assemblage of the soil microbial community. However, variations in the taxonomic attributes of the rhizosphere soil bacterial community arising from the Hg speciation in paddy soil, amended with natural S-rich biochar (NSBC) derived from the pyrolysis of S-rich oilseed rape straw, remain unclear. Herein, a rice pot experiment was conducted. Hg-polluted paddy soils were amended with NSBC and low-S biochar (LSBC) to evaluate the role of Hg chemical form affected by NSBC in regulating the taxonomic attributes of rhizosphere soil, including microbial abundance, composition, and ecological clusters within the co-occurrence network of microbial communities. Results showed that microbial abundance was higher in soils with lower Hg levels, and mean increases of 149 observed operational taxonomic units (OTUs) and 238 predicted OTUs (Chao 1) were observed, with a 1 mg kg-1 decrease in the total Hg (T-Hg) content. Among the 13 predictor variables, the T-Hg content was the strongest and most consistent predictor of the bacterial taxonomic attributes. This finding may be attributed to the fact that the drastic reduction in T-Hg and Hg bioavailability induced by NSBC results in the decrease of Hg stress on the soil microbiome. Moreover, NSBC amendment shifted the ecological clusters toward the amelioration of Hg pollution.

Anaerobic digestion of chicken manure: Sequences of chemical structures in dissolved organic matter and its effect on acetic acid production.

The use of chicken manure (CM) leads to serious environmental pollution due to the existence of bacteria and insect pests. Anaerobic digestion (AD) is one of the important technologies of CM treatment. However, methane production is limited by the accumulation of short-chain fatty acids (SCFAs) from AD. Therefore, the study explored the possible formation mechanism of acetic acid by understanding the effect of sequences of chemical structure variation in DOM on acetic acid production. The chemical structures of DOM were observed. The tyrosine-like substances (C1, 53.53-29.99%) and humic-like substances (C3, 18.38-5.96%) showed a tendency to decrease. Tryptophan-like substances (C2, 28.09-64.04%) showed the increasing trend. The results indicated that C2 was unwilling to biodegrade. In DOM, the order of biodegradability was C2< C1< C3. AD resulted in the enrichment of N-H in-plane (0-22.75%) and COO- stretch (7.53-18.57%) and the loss of O-H stretch (19.39-13.72%), C-H stretch (4.56%-0), CC stretch (12.04-9.61%) and C-O stretch (10.02-5.03%). Two-dimensional correlation spectroscopy is applied to investigate the sequences of chemical structures in DOM, the order is as follows: CC stretch > COO- stretch > N-H in-plane > C-O stretch. The result confirmed that protein was rapidly decomposed and utilized, which would result in the increase of microorganism metabolism and hydrolysis rate, polysaccharide was hydrolyzed to form phenol and carboxylic acid. Four possible pathways were identified in AD by the structural equation model. C1and hydroxyl can promote propionic and butyric acid formation by the pathway of valeric or iso-butyric acid production and further effected acetic acid production. This study proposed the possible formative mechanisms of acetic acid according to sequences of chemical structures variation in DOM during AD, which can provide the theoretical basis for directional regulating the conversion of different chemical structures of DOM into acetic acid in AD.