Although landfill is suspected to be releasing microplastics to the environment, there is few empirical researches carried out. To clarify suspicions of landfills as potential sources of ...microplastics, twelve leachate samples from four active and two closed municipal solid waste landfills were investigated. Microplastics were found in all the landfill leachate samples. In total, seventeen different types of plastics were identified in the leachate samples with calculated concentration ranging from 0.42 to 24.58 items/L. Polyethylene and polypropylene were the predominant polymer types. 99.36% microplastics were derived from the fragmentation of plastic waste buried in landfills. The size of 77.48% microplastics was between 100 and 1000 μm. The study shows that the generation, accumulation and release of microplastic in landfills is a long-term process. The results of our study provide preliminary evidence and validate that landfill isn't the final sink of plastics, but a potential source of microplastics.
•Municipal solid waste landfills are potential sources of microplastics.•Seventeen types of plastics were found in the landfill leachate.•The concentration of microplastics ranged from 0.42 to 24.58 items/L.•Polyethylene and polypropylene were the predominant polymer types.•99.36%microplastics derived from the fragmentation of plastic waste.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The addition of 0.5–1 mm biostable biochar (10 g/L) to mesophilic anaerobic digesters inoculated with crushed granules (1 g-VS/L) and fed with 4, 6 and 8 g/L glucose shortened the methanogenic lag ...phase by 11.4%, 30.3% and 21.6% and raised the maximum methane production rate by 86.6%, 21.4% and 5.2%, respectively, compared with the controls without biochar. 75 μm biochar further shortened the lag phase by 38.0% and increased the methane production rate by 70.6% at 6 g/L glucose loading. Biochar also simultaneously enhanced the production and degradation of intermediate acids. The fingerprint and sequencing analysis used to examine the spatial distribution and temporal evolution of communities revealed that proportion of Archaea was higher in the biochar-added treatments and in the tightly-bound fractions. Methanosarcina located in the tightly-bound fractions on the biochar surface, and was most abundant in the larger 2–5 mm biochar particles. Methanosaeta was enriched in the loosely-bound fractions by all-size biochar particles and within the tightly-bound fractions by small biochar particles. Because biochar is cost-effective and can remain in digestate for direct use as soil amendment without separation, eco-compatible biochar may serve as a good substrate for highly-loaded digestion by inducing selective colonization of functional microbes.
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•Stratified distribution of microbial community around biochar particle was explored.•Treatment with both biochar and high organics had more tightly bound Methanosarcina.•Bacteria was distinguished into suspended and biochar attached.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
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•Bottom ash from municipal solid waste incinerators was a source of microplastics.•Abundance of microplastics ranged from 1.9–565 n/kg-bottom ash.•Polypropylene was the predominant ...polymer types.•Per metric ton waste will produce 360 to 102,000 MPs in bottom ash.
It is widely accepted that incineration can permanently eliminate plastic waste. However, unburned material still exists in the bottom ash that is a solid residue from incinerators. In this study, microplastics exacted from bottom ash in 12 mass burn incinerators, one bottom ash disposal center and four fluidized bed incinerators were identified by micro-Fourier transform infrared spectroscopy. The results showed that bottom ash was a neglected microplastics source with an abundance of 1.9–565 n/kg, which indicated that per metric ton waste produce 360 to 102,000 microplastic particles after incineration. Nine types of plastics were identified, of which polypropylene and polystyrene were the predominant types. Microplastics sized between 50 μm and 1 mm accounted for 74 %. Granules, fragments, film, and fibers accounted for 43 %, 34 %, 18 %, and 5 % of the microplastics, respectively. The abundance of microplastics differed significantly with whether the local waste was source-separated, the local gross domestic product per capita, and the types of furnace. The global microplastics emission from incineration bottom ash was then estimated. Our observations provide empirical evidence proving that incineration is not the terminator of plastic waste, and bottom ash is a potential source of microplastics released into the environment.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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•Recycled biochar-biofilm consortia demonstrated feasible long-term application in AD.•Biochar < 5 μm more efficiently initiated methanogenesis than biochar > 1 mm.•Biochar < 5 μm ...enriched 20 times more microorganisms than larger biochar.•Methanosarcina dominated in biochar > 1 mm, while SAOB dominated in biochar < 5 μm.
Several single dose studies found that biochar was an effective additive promoting methanogenesis in anaerobic digestion. However, little attention was paid to the continuity of the biofilm formed on biochar and the subsequent evolution of microorganisms. In this study, the continuous performance and changes were quantified when biochar-biofilm consortia were applied as the recyclable inoculant to four cycles of acetate methanogenesis with increasing acetate loading. Biochar-biofilm consortia as the inoculant were found to consistently realize stable methane production, despite the removal of planktonic microorganisms in the reactor, and no extra inoculum and biochar were added. Consortia with biochar particles smaller than 5 μm promoted initiation of methanogenesis more rapidly than those with biochar particles larger than 1 mm, especially when the activity of microorganism was low. Moreover, the microorganisms were enriched throughout the continuous cycles. Biochar < 5 μm was found to accumulate 6.6–7.1 E + 11 16S copies per gram in the 3rd and 4th cycles, which was about 27–51 times that of biochar > 1 mm and also comparable to a fresh sludge inoculum. In addition, specific functional methanogens proliferated during continuous application. Methanosarcina was dominant in biochar > 1 mm, while the syntrophic acetate oxidizing bacteria Thermovirga and Mesotoga accounted for the majority of microorganisms in biochar < 5 μm. Therefore, with the competitive total cell count dominated by functional microorganisms, biochar-biofilm consortia demonstrated feasible recycling and reuse for bioaugmentation purposes or in the economical long-term application of anaerobic digestion for waste or wastewater treatment.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
YTH Domain Containing 1 (YTHDC1) is one of the m
A readers that is essential for oocyte development and tumor progression. The role of YTHDC1 in neuronal survival and ischemic stroke is unknown. ...Here, we found that YTHDC1 was unregulated in the early phase of ischemic stroke. Knockdown of YTHDC1 exacerbated ischemic brain injury and overexpression of YTHDC1 protected rats against brain injury. Mechanistically, YTHDC1 promoted PTEN mRNA degradation to increase Akt phosphorylation, thus facilitating neuronal survival in particular after ischemia. These data identify YTHDC1 as a novel regulator of neuronal survival and modulating m
A reader YTHDC1 may provide a potential therapeutic target for ischemic stroke.
•Biochar accelerated the humification progress of sludge organics.•Biochar increased oxygen uptake rates of sewage sludge during aerobic degradation.•SEM showed the porosity of the sludge surface ...increased with 12–18% biochar amended.
Wood biochar (6%, 12% and 18% of fresh sludge weight) adding to a sludge-and-straw composting system was investigated to assess the potential of biochar as a composting amendment. Organic degradation efficiency, temporal humification profile of the water-extractable organic fraction and solid organic matter, through spectroscopic, microscopic and elementary analysis were monitored. Fluorescent excitation and emission matrix indicated that concentrations of aqueous fulvic-acid-like and humic-acid-like compounds were, respectively, 13–26% and 15–30% higher in the biochar-amended treatments, than those in the control without biochar-amended. On the first day of sludge aerobic incubation, the presence of biochar resulted in increased oxygen uptake rates of 21–37% due to its higher nano-porosity and surface area. SEM indicated that, in the biochar-amended sludge, the dense microstructure on the sludge surface disintegrated into fragments with organic fraction degraded and water lost. Results indicated that 12–18%w/w addition of wood biochar to sludge composting was recommended.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
CO is a promising substrate for producing biochemicals and biofuels through mixed microbial cultures, where carboxydotrophs play a crucial role. The previous investigations of mixed microbial ...cultures focused primarily on overall community structures, but under-characterized taxa and intricate microbial interactions have not yet been precisely explicated. Here, we undertook DNA-SIP based metagenomics to profile the anaerobic CO-driven microbiomes under 95 and 35% CO atmospheres. The time-series analysis of the isotope-labeled amplicon sequencing revealed the essential roles of Firmicutes and Proteobacteria under high and low CO pressure, respectively, and Methanobacterium was the predominant archaeal genus. The functional enrichment analysis based on the isotope-labeled metagenomes suggested that the microbial cultures under high CO pressure had greater potential in expressing carboxylate metabolism and citrate cycle pathway. The genome-centric metagenomics reconstructed 24 discovered and 24 under-characterized metagenome-assembled genomes (MAGs), covering more than 94% of the metagenomic reads. The metabolic reconstruction of the MAGs described their potential functions in the CO-driven microbiomes. Some under-characterized taxa might be versatile in multiple processes; for example, under-characterized Rhodoplanes sp. and Desulfitobacterium_A sp. could encode the complete enzymes in CO oxidation and carboxylate production, improving functional redundancy. Finally, we proposed the putative microbial interactions in the conversion of CO to carboxylates and methane.
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NUK, SBMB, SBNM, UL, UM, UPUK
A novel and efficient protocol for the synthesis of various 2,4-disubstituted, 1,2,4-trisubstituted and 1,2,4,5-tetra-substituted imidazoles via cascade palladium catalyzed C-C coupling followed by ...intramolecular C-N bond formation was developed. Readily accessible boronic acids and N-substituted-2-aminoacetonitriles were firstly reported as starting materials to construct di-, tri-, and tetra-substituted imidazoles in good to excellent yield.
Combined effects of acids and ammonium on functional pathway and microbial structure during organics methanization were investigated by stable isotopic method and quantitative PCR. The results showed ...that the stress from acids and ammonium was synergetic, resulted in different inhibition for acetoclastic and hydrogenotrophic methanogenesis and syntrophic acetate oxidation, leading to pathway shift. Methane production from acetate was affected more by acetate than by ammonium until the ammonium concentration reached 6–7 g-N/L. When the ammonium concentration exceeded 6 g-N/L, ammonium inhibition was strengthened by the increased concentration of acetate. At a low acetate concentration (50 mmol/L), acetoclastic methanogenesis dominated, regardless of ammonium concentration. At higher acetate concentrations (150 and 250 mmol/L) and at low-medium ammonium levels (1–4 g-N/L), acetate was mainly degraded by acetoclastic methanogenesis, while residual acetate was degraded by a combination of acetoclastic methanogenesis and the syntrophic reaction of syntrophic acetate oxidization and hydrogenotrophic methanogenesis with the latter dominating at 250 mmol/L acetate. At high ammonium levels (6–7 g-N/L), the degradation of acetate in the 150 mmol/L treatment was firstly through a combination of acetoclastic methanogenesis and the syntrophic pathway and then gradually shifted to the syntrophic pathway, while the degradation of acetate in the 250 mmol/L treatment was completely by the syntrophic pathway.
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► Methanogenetic pathway shifted at the synergetic stress of acid and ammonium. ► Acetoclastic methanogenesis wasn't inhibited by 1–7 g-N/L ammonium at 0.05 M acids. ► Syntrophic acetate oxidization was inhibited by high levels of 6–7 g-N/L ammonium. ► Methanosarcinaceae shifted methanogenic pathway depending on the combined stress. ► Soluble microbial products accumulated at 0.25 M acids and 6–7 g-N/L ammonium.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
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