Effects of long-term exposure to zinc on performances of anaerobic digesters for swine wastewater treatment under various organic loading rates.

The long-term performance of anaerobic digestion (AD) often decreases substantially when treating swine wastewater contaminated with heavy metals. However, the toxicological characteristics and mechanisms of continuous exposure to heavy metals under different organic loading rates (OLR) are still poorly understood. In these semi-continuous AD experiments, it was found that zinc concentrations of 40 mg/L only deteriorated the reductive environments of AD. In comparison, a concentration of 2.0 mg/L probably facilitated the reproduction of microorganisms in the operating digesters with a constant OLR of 0.51 g COD/(L·d). Nevertheless, when the OLR was increased to 2.30 g COD/(L·d), 2.0 mg/L zinc inhibited various life activities of microorganisms at the molecular level within only 10 days. Hence, even though 2.0 mg/L zinc could promote AD performances from a macroscopic perspective, it had potential inhibitory effects on AD. Therefore, this study deepens the understanding of the inhibitions caused by heavy metals on AD and the metabolic laws of anaerobic microorganisms in swine wastewater treatment. These results could be referred to for enhancing AD in the presence of zinc in practical swine wastewater treatment.

Micro-nanobubble-assisted As(III) removal from water by Ni-doped MOF materials.

Micro-nanobubbles (MNBs) can form reactive oxygen species (ROS) with high oxidizing potential. In this study, nickel-doped metal-organic framework materials (MOFs) capable of activating molecular oxygen were synthesized using trivalent arsenic (As(III)) as a target pollutant and combined with peroxymonosulfate (PMS) to construct a MOF/MNB/PMS system. The results included the rapid oxidation of As(III), the successful absorption of oxidized As(V), and finally the efficient removal of As. The effects of pH, amount of PMS used, and preparation time of MNBs on the As removal performance of the MOF/MNB/PMS system were investigated experimentally. The changes in the properties of the materials before and after the reaction were analyzed by XPS, and it was found that the main active sites on the surface of the MOFs were the metal elements and the pyridine nitrogen near the carbon atom. The regular morphology and elemental composition of the MOFs were determined by TEM scanning and EDS test, which indicated the presence of nickel. XRD tests before and after the reaction showed that the MOFs were structurally stable. The results of the free radical burst experiments show that the single linear oxygen (1O2) is the main active substance in the system, and that the MNBs are key factors by which the system achieves efficient oxidation performance. In addition to providing a sustainable supply of molecular oxygen to the MOFs during the reaction process, coupling the MNBs with PMS was found to improve the oxidation capacity of the system. The results of this study thus provide a new concept for As removal and advanced oxidation in water bodies.

Research on the Mechanism of Metaldehyde on Pomacea canaliculata.

Golden apple snail (Pomacea canaliculata), a major alien invasive organism in China, affects food production and poses a threat to human health. Metaldehyde is a highly effective, commonly used snail killer with low toxicity. Virulence determination, tissue section, iTRAQ and RNA interference were used to systematically study the toxicity of metaldehyde on P. canaliculata. The molluscicidal activity tests showed that metaldehyde exhibits strong toxicity against P. canaliculata. Physiological and biochemical data indicate that metaldehyde can cause damage to the gills, liver, pancreas, and kidneys of snails, also reduce the oxygen consumption rate and ammonia excretion rate of golden apple snails, and cause neurological diseases. The proteome of the gill region of the golden apple snail after exposure to metaldehyde was analyzed by using iTRAQ technology. A total of 360 differential proteins were identified, and four target proteins were screened, namely, alpha-protein kinase 1 (ALPK1), cubilin (CUBN), sodium- and chloride-dependent GABA transporter 2 (GAT2), and acetylcholinesterase (AChE). RNAi was used to target the four proteins. After the ALPK1 and CUBN protein genes were interfered with by metaldehyde treatment, it was found that the mortality rate of the golden apple snail significantly increased. However, interference of GAT2 and AChE protein genes by metaldehyde led to no significant change in the mortality rates of the snails. The histopathological observation of the gill showed that the rate of cilia shedding in the gill decreased after the interference of ALPK1 and CUBN protein genes.

Efficient Proton Transfer and Charge Separation within Covalent Organic Frameworks via Hydrogen-Bonding Network to Boost H2O2 Photosynthesis.

Photocatalytic synthesis based on the oxygen reduction reaction (ORR) has shown great promise for H2O2 production. However, the low activity and selectivity of 2e- ORR result in a fairly low efficiency of H2O2 production. Herein, we propose a strategy to enhance the proton-coupled electron transfer (PCET) process in covalent organic frameworks (COFs), thereby significantly boosting H2O2 photosynthesis. We demonstrated that the construction of a hydrogen-bonding network, achieved by anchoring the H3PO4 molecular network on COF nanochannels, can greatly improve both proton conductivity and photogenerated charge separation efficiency of COFs. Thus, COF@H3PO4 exhibited superior photocatalytic performance in generating H2O2 without sacrificial agents, with a solar-to-chemical conversion efficiency as high as 0.69%. Results indicated that a much more localized spatial distribution of energy band charge density on COF@H3PO4 led to efficient charge separation, and the small energy barrier of the rate-limiting step from *OOH to H2O2 endowed COF@H3PO4 with higher 2e- ORR selectivity.

Molluscicidal effect mechanism study on metaldehyde to Pomacea canaliculate at low temperature.

BACKGROUND: Metaldehyde is a molluscicide commonly used to control Pomacea canaliculate. Its efficacy is significantly impacted by water temperature, although the underlying mechanisms have not been fully explored. RESULTS: In this study, we systematically investigated the temperature effect and molecular mechanisms of metaldehyde on P. canaliculata. The molluscicidal effect at various temperatures indicated that metaldehyde's molluscicidal activity significantly decreases with a drop in temperature. The LC50 value was only 458.8176 mg/L at 10 °C, while it surged to a high of 0.8249 mg/L at 25 °C. The impact of low temperature (10 °C) on metaldehyde's molluscicidal activity was analyzed via transcriptomics. The results revealed that the effect of low temperature primarily influences immunity, lipid synthesis, and oxidative stress. The expression of stress and immune-related genes, such as MANF, HSP70, Cldf7, HSP60, and PclaieFc, significantly increased. Furthermore, we studied the function of five target genes using RNA interference (RNAi) and discovered that Cldf7 and HSP70 could notably affect metaldehyde's molluscicidal effect. The mortality of P. canaliculata increased by 36.17% (72 h) after Cldf7 interference and by 48.90% (72 h) after HSP70 interference. CONCLUSION: Our findings demonstrate that low temperature can induce the extensive expression of the Cldf7 and HSP70 genes, resulting in a substantial reduction in metaldehyde's molluscicidal activity. © 2024 Society of Chemical Industry.

Chemical structure of hydrocarbons significantly affects removal performance and microbial responses in gas biotrickling filters.

The control of emissions of short-chain hydrocarbons with different structures is critical for the petrochemical industry. Herein, three two-carbon-containing (C2) hydrocarbons, ethane, ethylene, and acetylene, were chosen as pollutants to study the effects of chemical structure of hydrocarbons on removal performance and microbial responses in biotrickling filters. Results showed that the removal efficiency (RE) of C2 hydrocarbons followed the sequence of acetylene > ethane > ethylene. When the inlet loading rate was 30 g/(m3·h) and the empty bed residence time was 60 s, the RE of ethane, ethylene, and acetylene was 57 ± 4.0 %, 49 ± 1.0 %, and 84 ± 2.7 %, respectively. The high water solubility resulted in the high removal of C2 hydrocarbons, while a low surface tension enhanced the removal of C2 hydrocarbons. Additionally, the microbial community, enzyme activity, and extracellular properties of microorganisms also contributed to the difference in C2 hydrocarbon removal. These results could be referred for the effective control of light hydrocarbon emissions.

Role of LINC00240 on T-helper 9 differentiation in allergic rhinitis through influencing DNMT1-dependent methylation of PU.1.

BACKGROUND: Allergic rhinitis (AR) is a common allergic disease with increasing prevalence globally. However, the molecular mechanism underlying AR pathogenesis remains largely undefined. METHODS: Peripheral blood and nasal mucosa samples obtained from patients with AR (n = 22), and ovalbumin-induced AR mouse model (n = 8 per group) were prepared for subsequent detection. qRT-PCR and western blot were used to detect the expression of LINC00240, miR-155-5p, PU.1 and other key molecules. ELISA assay and flow cytometry were employed to evaluate the secretion of IL-9 and T-helper 9 (Th9) cell ratio, respectively. Bioinformatics analysis, RNA immunoprecipitation (RIP), chromatin immunoprecipitation (ChIP) and luciferase reporter assays were employed to further elucidate the regulatory network of LINC00240/miR-155-5p/DNMT1. The methylation of PU.1 promoter was assessed by methylation-specific PCR (MSP). This signaling axis was further validated in the mouse model of AR. RESULTS: LINC00240 was downregulated, while miR-155-5p and PU.1 were upregulated in the peripheral blood and nasal mucosa of AR patients, as well as in AR mice. This was accompanied with the increased ratio of Th9 cells and elevated IL-9 secretion. Mechanistically, LINC00240 served as a miR-155-5p sponge, and DNMT1 was a target of miR-155-5p. In addition, DNMT1 mediated the methylation of PU.1 promoter. In vivo studies verified that LINC00240 mitigated AR progression, possibly via miR-155-5p/DNMT1/PU.1-dependent Th9 differentiation. CONCLUSION: The involvement of LINC00240 in AR pathogenesis is closely associated with Th9 differentiation through modulating DNMT1-dependent methylation of PU.1 by sponging miR-155-5p.

Cobalt doping amount determines dominant reactive species in peroxymonosulfate activation via porous carbon catalysts co-doped by cobalt and nitrogen.

Switching the reaction routes in peroxymonosulfate (PMS)-based advanced oxidation processes have attracted much attention but remain challenging. Herein, a series of Co-N/C catalysts with different compositions and structures were prepared by using bimetallic zeolitic imidazolate frameworks based on ZIF-8 and ZIF-67 (xZn/Co-ZIFs). Results show that Co doping amount could mediate the transformation of the activation pathway of PMS over Co-N/C. When Co doping amount was less than 10%, the constructed xCo-N/C/PMS system (x ≤ 10%) was singlet oxygen-dominated reaction; however further increasing Co doping amount would lead to the generation and coexistence of sulfate radicals and high-valent cobalt, besides singlet oxygen. Furthermore, the nitrogen-coordinated Co (Co-NX) sites could serve as main catalytically active sites to generate singlet oxygen. While excess Co doping amount caused the formation of Co nanoparticles from which leached Co ions were responsible for the generation of sulfate radicals and high-valent cobalt. Compared to undoped N/C, Co doping could significantly enhance the catalytic performance. The 0.5% Co-N/C could achieve the optimum degradation (0.488 min-1) and mineralization abilities (78.4%) of sulfamethoxazole among the investigated Co-N/C catalysts, which was superior to most of previously reported catalysts. In addition, the application prospects of the two systems in different environmental scenarios (pH, inorganic anions and natural organic matter) were assessed and showed different degradation behaviors. This study provides a strategy to regulate the reactive species in PMS-based advanced oxidation process.

Electronic Phosphide-Support Interactions in Carbon-Supported Molybdenum Phosphide Catalysts Derived from Metal-Organic Frameworks.

Interfacial interaction in carbon-supported catalysts can offer geometric, electronic, and compositional effects that can be utilized to regulate catalytically active sites, while this is far from being systematically investigated in carbon-supported phosphide catalysts. Here, we proposed a novel concept of electronic phosphide-support interaction (EPSI), which was confirmed by using molybdenum phosphide (MoP) supported on nitrogen-phosphorus codoped carbon (NPC) as a model catalyst (MoP@NPC). Such a strong EPSI could not only stabilize MoP in a low-oxidation state under environmental conditions but also regulate its electronic structure, leading to reduced dissociation energy of the oxygen-containing intermediates and enhancing the catalytic activity for oxidative desulfurization. The removal of dibenzothiophene over the MoP@NPC was as high as 100% with a turnover frequency (TOF) value of 0.0027 s-1, which was 33 times higher than that of MoP without EPSI. This work will open new avenues for the development of high-performance supported phosphide catalysts.

Simultaneous adsorption and biodegradation of oxytetracycline in wastewater by Mycolicibacterium sp. immobilized on magnetic biochar.

Due to the adverse effects of long-term oxytetracycline (OTC) residues in aquatic environments, an effective treatment is urgently needed. Immobilized microbial technology has been widely explored in the treatment of various organic pollutants in aquatic environments with its excellent environmental adaptability. Nevertheless, studies on its application in the removal of antibiotics are relatively scarce and not in sufficient depth. Only a few studies have further investigated the final fate of antibiotics in the immobilized bacteria system. In this study, a novel kind of OTC-degrading bacteria Mycolicibacterium sp. was immobilized on straw biochar and magnetic biochar, respectively. Magnetic biochar was proved to be a more satisfactory immobilization carrier due to its superior property and the advantage of easy recycling. Compared with free bacteria, immobilized bacteria had stronger environmental adaptability under different OTC concentrations, pH, and heavy metal ions. After 5 cycles, immobilized bacteria could still remove 71.8% of OTC, indicating that it had a stable recyclability. Besides, OTC in real swine wastewater was completely removed by immobilized bacteria within 2 days. The results of FTIR showed that bacteria were successfully immobilized on biochar and O-H, N-H, and C-N groups might be involved in the removal of OTC. The fate analysis indicated that OTC was removed by simultaneous adsorption and biodegradation, while biodegradation (92.8%) played a dominant role in the immobilized bacteria system. Meanwhile, the amount of adsorbed OTC (7.20%) was rather small, which could effectively decrease the secondary pollution of OTC. At last, new degradation pathways of OTC were proposed. This study provides an eco-friendly and effective approach to remedy OTC pollution in wastewater.

Causal relationship between Butyricimonas and allergic asthma: a two-sample Mendelian randomization study.

Background: Growing evidence has well documented the close association between the gut microbiome and allergic respiratory disease, which has been notably represented by allergic asthma. However, it is unclear whether this association is a causal link. Therefore, we investigated the potential causal associations between the gut microbiome and allergic asthma or other allergic diseases. Methods: In this study, we performed two-sample Mendelian randomization (MR) analyses by using the publicly available genome-wide association study (GWAS) summary data. Single-nucleotide polymorphisms (SNPs) that significantly correlated were selected as instrumental variables. The inverse variance weighted (IVW) method was used to examine the potential causal gut microbial genera for allergic asthma and other allergic diseases. The robustness of the primary findings of the MR analyses was ensured by using different sensitivity analyses. Results: Combining the findings from multiple analyses, the host genetic-driven increases in Butyricimonas at the genus level were positively correlated with the risk of allergic asthma. In addition, phylum Bacteroidetes and class Bacteroidia were also found to have negative associations with the risk of allergic asthma; genus Slackia was identified as having potential causal effects with allergic asthma. No clear evidence of pleiotropy and heterogeneity was observed in genus Butyricimonas. Butyricimonas was also found to have an association with allergic rhinitis, but not with other allergic diseases. Conclusion: Our findings indicate that there are new gut microbial genera that were causally associated with the risk of allergic asthma and other allergic diseases, and offer novel insights into the pathogenesis of allergic respiratory diseases.

Generation and engineering applications of sulfate radicals in environmental remediation.

Sulfate radical (SO4•-)-based advanced oxidation processes (AOPs) have become promising alternatives in environmental remediation due to the higher redox potential (2.6-3.1 V) and longer half-life period (30-40 µs) of sulfate radicals compared with many other radicals such as hydroxyl radicals (•OH). The generation and mechanisms of SO4•- and the applications of SO4•--AOPs have been examined extensively, while those using sulfite as activation precursor and their comparisons among various activation precursors have rarely reviewed comprehensively. In this article, the latest progresses in SO4•--AOPs were comprehensively reviewed and commented on. First of all, the generation of SO4•- was summarized via the two activation methods using various oxidant precursors, and the generation mechanisms were also presented, which provides a reference for guiding researchers to better select two precursors. Secondly, the reaction mechanisms of SO4•- were reviewed for organic pollutant degradation, and the reactivity was systematically compared between SO4•- and •OH. Thirdly, methods for SO4•- detection were reviewed which include quantitative and qualitative ones, over which current controversies were discussed. Fourthly, the applications of SO4•--AOPs in various environmental remediation were summarized, and the advantages, challenges, and prospects were also commented. At last, future research needs for SO4•--AOPs were also proposed consequently. This review could lead to better understanding and applications of SO4•--AOPs in environmental remediations.

Catalytic activity and reaction mechanisms of single-atom metals anchored on nitrogen-doped carbons for peroxymonosulfate activation.

Single-atom catalysts have attracted tremendous interests in peroxymonosulfate (PMS)-based advanced oxidation processes due to their maximum atom utilization and high reactivity, however the role of nitrogen-coordinated metal (MNx) sites with different metal centers remain blurred. Herein, a series of single-atom metals anchored on nitrogen-doped carbons (denoted as M-N/C, M = Fe, Co, Cu, and Mn) using zeolitic imidazolate frameworks as precursors are constructed for PMS activation. Their catalytic activity order follows Fe > Co > undoped N/C > Cu > Mn, especially the degradation rates of the eight model pollutants for Fe-N/C and Co-N/C are 2.5-22.4 and 1.5-19.5 times higher than those for undoped N/C, respectively. Moreover, the nature of catalytic metal center can govern the degradation behaviors in the coexisting water constituents. Experimental and theoretical results reveal that singlet oxygen (1O2) is the main oxidant responsible for pollutant degradation and its evolution path over FeN4 or CoN4 sites (PMS→OH*→*O→1O2) is elucidated, between which FeN4 with lower energy barrier is more conducive to 1O2 generation. This study can not only provide guidance for the development of highly active atomic M-N/C catalysts, but also lead to a better molecular-level understanding of PMS activation mechanism over MN4 sites.

Effect of composition of volatile fatty acids on yield of polyhydroxyalkanoates and mechanisms of bioconversion from activated sludge.

Polyhydroxyalkanoates (PHA) is green biodegradable natural polymer. Here PHA production from volatile fatty acids (VFAs) was investigated in sequential batch reactors inoculated with activated sludge. Single or mixed VFAs ranging from acetate to valerate were evaluated, and the dominant VFA concentration was 2 times of that of the others in the tests. Results showed that mixed substrates achieved about 1.6 times higher yield of PHA production than single substrate. The butyrate-dominated substrates maximized PHA content at 72.08% of VSS, and the valerate-dominated substrates were followed with PHA content at 61.57%. Metabolic flux analysis showed the presence of valerate in the substrates caused a more robust PHA production. There was at least 20% of 3-hydroxyvalerate in the polymer. Hydrogenophaga and Comamonas were the main PHA producers. As VFAs could be produced in anaerobic digestion of organic wastes, the methods and data here could be referred for efficient green bioconversion of PHA.

Stress of cupric ion and oxytetracycline in Chlorella vulgaris cultured in swine wastewater.

Chlorella culturing has the advantages in treatment of wastewater including swine wastewater from anaerobic digesters due to the product of biolipids and the uptake of carbon dioxide. However, there often exist high concentrations of antibiotics and heavy metals in swine wastewater which could be toxic to chlorella and harmful to the biological systems. This study examined the stress of cupric ion and oxytetracycline (OTC) at various concentrations on the nutrient removal and biomass growth in Chlorella vulgaris culturing in swine wastewater from anaerobic digesters, and its biochemical responses were also studied. Results showed that dynamic hormesis of either OTC concentration or cupric ion one on Chlorella vulgaris were confirmed separately, and the presence of OTC not only did not limit biomass growth and lipids content of Chlorella vulgaris but also could mitigate the toxicity of cupric ion on Chlorella vulgaris in combined stress of Cu2+ and OTC. Extracellular polymeric substances (EPS) of Chlorella vulgaris were used to explain the mechanisms of stress for the first time. The content of proteins and carbohydrates in EPS increased, and the fluorescence spectrum intensity of tightly-bound EPS (TB-EPS) of Chlorella vulgaris decreased with increasing concentration of stress because Cu2+ and OTC may be chelated with proteins of TB-EPS to form non-fluorescent characteristic chelates. The low concentration of Cu2+ (≤1.0 mg/L) could enhance the protein content and promote the activity of superoxide dismutase (SOD) while these parameters were decreased drastically under 2.0 mg/L of Cu2+. The activity of adenosine triphosphatase (ATPase) and glutathione (GSH) enhanced with the increase of OTC concentration under combined stress. This study helps to comprehend the impact mechanisms of stress on Chlorella vulgaris and provides a novel strategy to improve the stability of microalgae systems for wastewater treatment.

Long Non Coding RNA FOXD3­AS1 Alleviates Allergic Rhinitis by Elevating the Th1/Th2 Ratio via the Regulation of Dendritic Cells.

This article aimed to explore whether the regulation of Th1/Th2 immune responses by FOXD3-AS1 is associated with dendritic cells (DCs) in allergic rhinitis (AR). HE staining was performed to assess the pathological changes in the nasal mucosa; ELISA was performed to measure the levels of Th1/Th2-related cytokines; flow cytometry was performed to analyze Th1/Th2 cells and MHC-II-, CD80-, and CD86-positive DCs; and qRT‒PCR and western blotting were performed to measure mRNA and protein expression levels, respectively. Our data revealed that LV-FOXD3-AS1 improved AR and increased the Th1/Th2 cell ratio in AR model mice. LV-FOXD3-AS1 further inhibited DC maturation both in vivo and in vitro. Moreover, the coculture system of DCs and CD4+ T cells demonstrated that LV-FOXD3-AS1 increased the Th1/Th2 cell ratio by inhibiting the maturation of DCs. In addition, LV-FOXD3-AS1 reduced the level of phosphorylated STAT6 in DCs derived from healthy mice, and STAT6 overexpression eliminated the inhibitory effect of LV-FOXD3-AS1 on the maturation of DCs. In summary, LV-FOXD3-AS1 ameliorated AR by increasing the Th1/Th2 cell ratio by inhibiting DC maturation via the inhibition of STAT6 phosphorylation. Our data confirmed the protective effect of FOXD3-AS1 in AR and provided a novel idea for the treatment of this disease.

Sublethal effects of niclosamide on the aquatic snail Pomacea canaliculata.

Pomacea canaliculata is a malignant invasive aquatic snail found worldwide, and niclosamide (NS) is one of the primary agents used for its control. NS applied to water will exist in non-lethal concentrations for some time due to degradation or water exchange, thus resulting in sublethal effects on environmental organisms. To identify sublethal effects of NS on Pomacea canaliculata, we studied the aspects of histopathology, oxygen-nitrogen ratio (RO∶N), enzyme activity determination, and gene expression. After LC30 NS treatment (0.310 g/L), many muscle fibers of the feet degenerated and some acinar vesicles of the hepatopancreas collapsed and dissolved. The oxygen-nitrogen ratio (RO∶N) decreased significantly from 15.0494 to 11.5183, indicating that NS had changed the metabolic mode of Pomacea canaliculata and shifted it primarily to protein catabolism. Transcriptome analysis identified the sublethal effects of LC30 NS on the snails at the transcriptional level. 386, 322, and 583 differentially expressed genes (DEGs) were identified in the hepatopancreas, gills, and feet, respectively. GO (Gene Ontology) functional analysis and KEGG (Kyoto Encyclopedia of Genes and Genomes) pathway annotations showed that DEGs in the hepatopancreas were mainly enriched for sugar metabolism, protein biosynthesis, immune response, and amino acid metabolism functional categories; DEGs in the gills were mainly enriched for ion transport and amino acid metabolism; DEGs in the feet were mainly enriched for transmembrane transport and inositol biosynthesis. In the future, we will perform functional validation of key genes to further explain the molecular mechanism of sublethal effects.

Combined effects of oxytetracycline concentration and organic loading rate on semi-continuous anaerobic digestion of swine wastewater.

High concentrations of antibiotics in swine wastewater raises concerns about the potential adverse effects of anaerobic digestion (AD). Current studies mainly focused on the effects of various antibiotic concentrations. However, these studies didn't take into account the fluctuation of swine wastewater quality and the change of reactor operating conditions in practical engineering applications. In this study, it was found that in the operating systems with COD of 3300 mg/L and hydraulic retention time (HRT) of 4.4 days, the continuous addition of oxytetracycline for 30 days had no effect on the AD performance. Nevertheless, when COD and HRT were changed to 4950 mg/L and 1.5 days respectively, oxytetracycline at 2 and 8 mg/L increased the cumulative methane yield by 27% and 38% at the cost of destroying cell membrane, respectively, while oxytetracycline at 0.3 mg/L improved the performance and stability of AD. These results could be referred for practical engineering applications.

Nitrogen removal of decentralized swine wastewater by pilot-scale source reduction - anaerobic baffled reactor - zoning constructed wetlands at low temperatures.

The study developed a cost-effective integrated technology to treat swine wastewater at the pilot-scale small pigsty. The swine wastewater, which was separated rinse water after flowing through the slatted floor and the innovatively constructed liquid-liquid separate collection device, was subsequently pumped into an anaerobic baffled reactor (ABR) and then through zoning constructed wetlands (CWs) comprised of CW1, CW2, and CW3. The liquid-liquid separate collection device effectively reduced COD, NH4-N, and TN by 57.82%, 52.39%, and 50.95%, respectively. The CW1 and CW2 enhanced TN removal and nitrification, respectively, through rapid adsorption-bioregeneration of zeolite. Moreover, rice straws were used as solid carbon sources in CW3 to successfully promote denitrification at 16.0 g/(m3·d). The integrated technology (slatted floor-liquid liquid separate collection-ABR-CWs) reduced COD, NH4-N, and TN by 98.17%, 87.22%, and 87.88%, respectively, at approximately 10 °C. Microbial analysis results confirmed that the CWs exhibited apparent functional zoning, with denitrifiers dominating in CW3, nitrifiers dominating in the zeolite layers of CW1 and CW2, and denitrifiers dominating in the brick slag layers of CWs. This cost-effective integrated technology demonstrated significant potential for treating swine wastewater at low temperatures.

Aging microplastic aggravates the pollution of heavy metals in rhizosphere biofilms.

Heavy metals (HMs) and microplastics (MPs) are ubiquitous in agricultural soils. Rhizosphere biofilms are important sites for HM adsorption, and biofilms are easily disturbed by soil MPs. However, the adsorption of HMs on rhizosphere biofilms induced by aged MPs is not clear. In this study, the adsorption behavior of Cd(II) on biofilms and pristine/aged polyethylene (PE/APE) was analyzed and quantified. The results showed that the adsorption amount of Cd(II) on APE was greater than that on PE, in which the oxygen-containing functional groups of APE could provide binding sites to increase the adsorption of HMs. Density functional theory (DFT) calculations revealed that the binding energy of Cd(II) onto APE (-6.00 kcal·mol-1) was much stronger than that of PE (7.11 kcal·mol-1) due to hydrogen bonding interactions and oxygen atom-metal interactions. For HM adsorption on MP biofilms, APE increased the adsorption capacity of Cd(II) by 4.7 % relative to PE. The pseudo-second-order kinetic and Langmuir models suitably described the adsorption kinetics and isothermal adsorption of Cd(II), respectively (R2 > 80 %), indicating that monolayer chemisorption dominated. However, the hysteresis indices of Cd(II) in the Cd(II)-Pb(II) system (< 1) were higher than those in the single system (> 1) due to the competitive adsorption of HMs. Overall, this study clarifies the effect of MPs on the adsorption of HMs in rhizosphere biofilms and will help researchers assess the ecological risks of HMs in soils.