Located in the Indo-Eurasian collision zone, the Parlung Tsangpo River is a hot spot for studying tectonic geomorphological responses because of its complex geomorphological environment. The purpose ...of this study was to explore the use of morphological analysis based on digital elevation model to reveal tectonic activities. The Parlung Tsangpo River is used as the study area to probe how hypsometric integrals (HI), longitudinal profiles (LP), and steepness indices (
K
s
) respond to tectonic activity. About 98% of the basin area is in the mature stage of geomorphic development; specifically, 49.7% is in sub-maturation, 48.4% is in late maturation, and 1.9% is in an old stage. The HI value at the river source is smaller than that in the middle reaches of the Parlung Tsangpo River, implying that the fracture activity in the region may remain active and persistent after the formation of the river. After considering all of the extracted LPs, four were determined to be distinct. Each of these four sections is straight and has at least one break point, indicating that most of these tributaries are in a period of intense erosion. A more active tectonic indication in the left upstream and Dongjiuqu regions was revealed based on their greater numbers of knickpoints. In addition, their
K
s
values were larger than in other regions, which was consistent with the LP results. When
K
s
values become larger, this often indicates the existence of a barrier dam in the Parlung Tsangpo River basin.
This study shows that the leaching caprolactam (CPL) in PA6 microplastics significantly enhanced methane production in anaerobic digestion of WAS.
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•PA6 microplastics motivate methane ...production in WAS anaerobic digestion.•PA6 microplastics offer marginal effect on solubilization and hydrolysis.•PA6 microplastics promote acidification and methanogenesis.•PA6 microplastics mainly affect anaerobic digestion by leaching caprolactam.
Polyamide 6 (PA6) as a typical emerging microplastic pollutant has frequently been featured in wastewater treatment plants (WWTPs), yet its associated impact on waste activated sludge (WAS) anaerobic digestion process have not been fully understood. This study identified the key role of PA6 microplastics (5–50 particles/g TS) in methane production during anaerobic digestion through biochemical methane production testing and model-based analysis, and explored the mechanism involved by monitoring the conversion of metabolic intermediates, the activity of key enzymes, and the effects of leachate caprolactam (CPL). Unlike other microplastics that normally inhibit anaerobic digestion, PA6 significantly enhanced methane production due to the effect of CPL. The presence of 10 particles PA6/g TS improved methane production by 39.5% (from 124 ± 6 to 173 ± 8 L CH4/kg VS). Model-based analysis showed that PA6 promoted methane production potential and volatile solids destruction. PA6 offered marginal effect on the solubilization and hydrolysis of WAS, the leaching of CPL improved acidification and methanogenesis due to the promotion of key enzyme activities, which is the main reason why PA6 increased methane production. These findings indicate that PA6 is less toxic to WAS anaerobic digestion than other microplastics, which prompts an understanding of the dual role of microplastics in WWTPs.
Polycarbonate (PC) microplastics are frequently detected in waste activated sludge. However, understanding the potential impact of PC microplastics on biological sludge treatment remains challenging. ...By tracking the changes in methane production under different concentrations of PC microplastics, a dose-dependent effect of PC microplastics on anaerobic digestion of sludge was observed. PC microplastics at 10–60 particles/g total solids (TS) improved methane production by up to 24.7 ± 0.1 % (at 30 particles/g TS), while 200 particles/g TS PC microplastics reduced methane production by 8.09 ± 0.1 %. Bisphenol A (BPA) leached from 30 particles/g TS PC microplastics (1.26 ± 0.18 mg/L) down-regulated intracellular reactive oxygen species (ROS) production, thereby enhancing enzyme activity, biomass viability, and abundance of methanogenic (Methanobacterium sp. and Methanosarcina sp.), ultimately boosting methane production. Conversely, BPA leached from 200 particles/g TS PC microplastics (4.02 ± 0.15 mg/L) stimulated ROS production, resulting in decreased biomass viability and even apoptosis. Modulation of oxidative stress by leaching monomeric BPA is an underappreciated transformative mechanism for improving the mastery of the potential behavior of microplastics in biological sludge treatment.
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•PC microplastics exhibited dose-dependent effects on sludge anaerobic digestion.•PC microplastics at 30 particles/g TS increased methane production by 24.7 ± 0.1 %.•BPA and PhOHs were the major chemicals leached from PC microplastics.•PhOHs had no obvious effect on sludge anaerobic digestion.•BPA induced variability of intracellular reactive oxygen species production.
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•Citric acid (CA) exhibits dose-dependent effects on the SCFAs promotion.•CA is mainly converted to acetic acid in the anaerobic fermentation system.•CA removes multivalent cations ...from extracellular polymeric substances (EPS).•CA facilitates WAS hydrolysis by disrupting EPS and microbial cells.•Microbial functional traits related to SCFAs production are regulated by CA.
Numerous effective chemical strategies have been explored for short-chain fatty acids (SCFAs) production from waste activated sludge (WAS), but many technologies have been questioned due to the chemical residues. This study proposed a citric acid (CA) treatment strategy for improving SCFAs production from WAS. The optimum SCFAs yield reached 384.4 mg COD/g VSS with 0.08 g CA/g TSS addition. Meanwhile, CA biodegradation occurred and its contribution to the yield of total SCFAs, especially acetic acid, cannot be ignored. Intensive exploration indicated the sludge decomposition, the biodegradability of fermentation substrates, as well as the abundance of fermenting microorganisms were definitely enhanced in the existence of CA. The optimization of SCFAs production techniques based on this study deserved further study. This study comprehensively revealed the performance and mechanisms of CA enhancing biotransformation of WAS into SCFAs and the findings promotes the research of carbon resource recovery from sludge.
The production of short-chain fatty acids (SCFAs) from waste activated sludge (WAS) via anaerobic fermentation is typically restricted by poor sludge decomposition capacity and low ...substrate-availability. Therefore, the free ammonia (FA)‑sodium percarbonate (SPC) technology was presented to successfully overcome the limitation while addressing unsatisfactory acidogenic fermentation pretreated with sole FA or SPC. It revealed that FA + SPC co-pretreatment could boost the SCFA concentration to 347.1 mg COD/g VSS at 180 mg/L FA and 0.15 g/g TSS SPC. In-depth studies demonstrated that FA + SPC pretreatment greatly improved sludge disintegration, biodegradability of substrates and acidification of hydrolysis products. Furthermore, FA + SPC co-pretreatment stimulated the activity of hydrolytic and acidogenic enzymes but inhibited methanogenic enzymes while changing the microbial structure and promoting the enrichment of fermentation microorganisms. The synergistic effect of FA and SPC in this work improves the yield of SCFAs from WAS and facilitates the study of WAS carbon resource recovery.
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•CTC promotes volatile fatty acid production from waste activated sludge.•10 mg/kg TSS CTC induces the highest volatile fatty acid accumulation.•CTC stimulates the secretion of ...extracellular polymeric substances.•CTC enhances acidification and inhibits methanation by regulating enzyme activity.
One of the key challenges of wastewater treatment today is to understand the potential effect of residual pollutants on the management of waste activated sludge (WAS). This study aims to clarify the effect of chlortetracycline (CTC) as a residual antibiotic on the anaerobic fermentation of WAS to produce volatile fatty acids (VFAs). The results show that CTC with a concentration of 10 mg/kg total suspended solids enhances the VFA production by 21.1%. Mechanistically, CTC was found to prompt the secretion of extracellular polymeric substances to provide more substrates for anaerobic fermentation. Meanwhile, CTC stimulates acidification by increasing the activity of acetate kinase, and inhibits methanogenesis by reducing F420 activity, thereby increasing the accumulation of VFAs. This article provides new insights into the behavior of CTC in WAS fermentation, which is essential for resource recovery from WAS containing CTC.
Obesity caused by poor eating habits has become a great challenge faced by public health organizations worldwide. Optimizing dietary intake and ingesting special foods containing biologically active ...substances (such as polyphenols, alkaloids, and terpenes) is a safe and effective dietary intervention to prevent the occurrence and development of obesity. Tea contains several active dietary factors, and daily tea consumption has been shown to have various health benefits, especially in regulating human metabolic diseases. Here, we reviewed recent advances in research on tea and its functional components in improving obesity-related metabolic dysfunction, and gut microbiota homeostasis and related clinical research. Furthermore, the potential mechanisms by which the functional components of tea could promote lipid-lowering and weight-loss effects by regulating fat synthesis/metabolism, glucose metabolism, gut microbial homeostasis, and liver function were summarized. The research results showing a "positive effect" or "no effect” objectively evaluates the lipid-lowering and weight-loss effects of the functional components of tea. This review provides a new scientific basis for further research on the functional ingredients of tea for lipid lowering and weight loss and the development of lipid-lowering and weight-loss functional foods and beverages derived from tea.
A variety of variables limit the recovery of resources from anaerobic fermentation of waste activated sludge (WAS), hence pretreatment strategies are necessary to be investigated to increase its ...efficiency. A combination of free nitrous acid (FNA) and calcium hypochlorite Ca(ClO)2 was employed in this investigation to significantly improve sludge fermentation performance. The yields of cumulative hydrogen for the blank and FNA treatment group were 1.09 ± 0.16 and 7.36 ± 0.21 mL/g VSS, respectively, and 6.59 ± 0.24 0.03 g Ca(ClO)2/g TSS, 7.75 ± 0.20 (0.06), and 8.58 ± 0.22 (0.09) mL/g VSS for the Ca(ClO)2 groups. The co-treatment greatly boosted hydrogen generation, ranging from 39.97 ± 2.26 to 76.20 ± 4.78 % as compared to the solo treatment. Mechanism analysis demonstrated that the combined treatment disturbed sludge structure and cell membrane permeability even more, which released more organic substrates and enhanced biodegradability of fermentation broth. This paper describes a unique strategy to sludge pretreatment that expands the use of Ca(ClO)2 and FNA in anaerobic fermentation, with implications for sludge disposal and energy recovery.
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•Effects of co-treatment with FNA and Ca(ClO)2 on hydrogen production in anaerobic fermentation was studied.•FNA + Ca(ClO)2 enhanced lysis and solubilization of sludge and breakage of cells.•FNA + Ca(ClO)2 promoted enrichment of hydrogen producers.•FNA + Ca(ClO)2 inhibited hydrogen consumption and methanogenesis.
Benzethonium chloride (BZC) is viewed as a promising disinfectant and widely applied in daily life. While studies related to its effect on waste activated sludge (WAS) anaerobic fermentation (AF) ...were seldom mentioned before. To understand how BZC affects AF of WAS, production of short chain fatty acids (SCFAs), characteristics of WAS as well as microbial community were evaluated during AF. Results manifested a dose-specific relationship of dosages between BZC and SCFAs and the optimum yield arrived at 2441.01 mg COD/L with the addition of 0.030 g/g TSS BZC. Spectral results and protein secondary structure variation indicated that BZC denatured proteins in the solid phase into smaller proteins or amino acids with unstable structures. It was also found that BZC could stimulate the extracellular polymeric substances secretion and reduce the surface tension of WAS, leading to the enhancement of solubilization. Beside, BZC promoted the hydrolysis stage (increased by 7.09 % to 0.030 g/g TSS BZC), but inhibited acetogenesis and methanogenesis stages (decreased by 6.85 % and 14.75 % to 0.030 g/g TSS BZC). The microbial community was also regulated by BZC to facilitate the enrichment of hydrolytic and acidizing microorganisms (i.e. Firmicutes). All these variations caused by BZC were conducive to the accumulation of SCFAs. The findings contributed to investigating the effect of BZC on AF of WAS and provided a new idea for the future study of AF mechanism.
Swertiamarin (SW), which belongs to iridoid glycosides, is one of the main components of Swertia plants in Gentianaceae family, including Swertia pseudochinensis H. Hara and Swertia mileensis T. N. ...Ho et W. L. Shi. There are mainly used in traditional Chinese medicine for the treatment of hepatic and biliary disease such as jaundice.
This experiment aimed to explore the protective mechanism of SW on cholestasis induced by alpha-naphthylisothiocyanate in rats.
Healthy rats were randomly divided into the control, model (ANIT, 50 mg/kg), ursodeoxycholic acid (UDCA, 80 mg/kg), and low-dose (SW, 80 mg/kg), medium-dose (SW, 100 mg/kg), and high-dose (SW, 150 mg/kg) groups. The hepatic protective effect of SW was preliminarily evaluated by measurement of serum biochemical indicators and liver morphological evaluation. Moreover, metabolomics and proteomics analysis were used to explore the protective mechanism of SW on cholestasis. The expression of related proteins was determined by Western blot and polymerase chain reaction, and the important proteins were verified by cell experiments in vitro.
SW (100 mg/kg) can reduce the serum levels of the model group. The hepatocyte of the medium-dose treatment group was arranged neatly without evident inflammation. SW can partially reverse the changes in cholestasis metabolites, such as taurocholic acid, SM (d18:1/16:0), all-trans-retinoic acid and other products of rats. The main metabolic pathways affected were primary bile acid synthesis, glycerophospholipid metabolism, sphingolipid metabolism and retinol metabolism. SW medium-dose treatment group showed effective reversal of 25 related proteins and it can remarkably reduce the contents of NTCP and CYP27A1 in rat liver and increase the protein expressions of CYP7A1, CYP8B1, bile salt export pump, multidrug resistance-associated protein and FXR.
SW can alleviate ANIT-induced cholestasis, which by activating the farnesoid X receptor and bile acid excretion pathway.
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•Multiomics technology were combined to study cholestasis.•Swertiamarin indeed attenuated ANIT-induced cholestasis.•The protective effect was processed by activating FXR and bile acid excretion pathways.•The involved proteins were verified by WB, RT-qPCR and immunofluorescence analysis.
