•α-MnO2/Pal composite was fabricated via a hydrothermal method.•α-MnO2/Pal effectively activates peroxymonosulfate (PMS) to degrade RhB.•Factors affecting RhB degradation by α-MnO2/Pal activation ...were evaluated.•Radicals of O2− and 1O2 played important role in the RhB degradation.•α-MnO2/Pal composite possessed an excellent reusability.
The discharging of Rhodamine B (RhB) from wastewater has caused huge environment pollution. Peroxymonosulfate (PMS) oxidation is an effective way to remove it from wastewater. However, finding an environmentally friendly metal to activate PMS is a key step for the oxidation process. In this study, nanorod α-MnO2 loaded palygorskite (α-MnO2/Pal) was fabricated by a simple hydrothermal method. The analysis of field emission scanning electron microscope (FE-SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) confirmed the loading of α-MnO2 on the surface of Pal and characterized the surface of the composite. The surface area of α-MnO2/Pal composite was 159.13 m2/g, which was much higher than that of Pal and α-MnO2. The Pal, α-MnO2, Mn2+, and α-MnO2/Pal were used to activate PMS for RhB degradation. Nearly 100% RhB degradation was obtained in α-MnO2/Pal + PMS system in 180 min and in α-MnO2 + PMS system in 300 min, while only 50% degradation was obtained in Pal + PMS system and 71.4% degradation in Mn2+ + PMS system in 300 min. The degradation fitted the pseudo-first-order reaction kinetics well with rate constant of 0.02041 min−1 for α-MnO2/Pal + PMS system, 0.01192 min−1 for α-MnO2 + PMS system, and 0.00435 min−1 for Mn2+ + PMS system, respectively. The factors affecting RhB degradation were further investigated. The RhB degradation efficiency increased with the increase of α-MnO2/Pal dosages, PMS dosages and temperatures. The degradation was inhibited at pH > 5.5, while was favorable at pH < 5.5. The major reactive radicals responsible for RhB degradation classified by radical quenching experiment were O2− and 1O2. The possible mechanism was further proposed based on the results. The α-MnO2/Pal composite showed nearly 50% mineralization ratio in the presence of PMS and an excellent reusability. The results from this study revealed that α-MnO2/Pal composite is an effective catalyst to activate PMS for RhB degradation.
•A superimposed model was developed to simulate two-peak methane production curves.•Methanogenic pathway shifted to hydrogenotrophic methanogenesis in dry AD.•Acetoclastic methanogenesis ...overwhelmingly dominated in wet AD.•High TS content at 20% decreased the specific methane yield.
Dry anaerobic digestion (AD) has advantages over wet AD in treating high-solid organic wastes like livestock and food wastes, but an elevated total solids (TS) content would affect the AD performances. In this study, methane production of digesters co-digesting pig manure (PM) and food waste (FW) at different TS contents (R1, TS 5%; R2, TS 10%; R3, TS 15%; and R4, TS 20%) was assessed. The results showed the specific methane yield had no significant difference with the increase of TS contents from 5% to 15% (278.8–291.7 NmL/g VSadded), while it was reduced at a 20% TS content (259.8 NmL/g VSadded). Two peaks of total volatile fatty acids and daily methane production were observed in the high-solid digesters (R2-R4), while only one peak occurred in wet AD (R1). A new kinetics model was developed to describe the two-peak methane production behavior at high TS contents. The analysis on the microbial community structure clearly showed the different evolutions of methanogenic pathways in low and high solids content systems. In dry AD (R4), there was a general shifting from the acetoclastic pathway, to mixotrophic pathway and hydrogenotrophic pathway, with the dominance of mixotrophic and hydrogenotrophic methanogens.
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•LDH/GO is synthesized to activate peroxymonosulfate (PMS).•LDH/GO + PMS system shows excellent performance for GAT degradation.•Comparing with LDH, heavy metals dissolving is ...controlled well in LDH/GO + PMS system.•LDH/GO can be reused many times and maintain effective catalysis.
Layered double hydroxide (LDH) was a kind of layer materials with multi-metal elements and good catalytic performance, but the metals can be dissolved during catalysis. Graphene oxide (GO) was a two-dimensional structure with abundant anionic groups with the potential of immobilizing metals. However, LDH combined with GO (LDH/GO) was few reported in the treatment of pharmaceuticals and personal care products (PPCPs). In this work, CoFeNi LDH/GO composites were designed and synthesized for activating peroxymonosulfate (PMS). Meanwhile, gatifloxacin (GAT), a typical antibiotic, was used to assess the performance of LDH/GO + PMS system. The characterization of LDH/GO using various measures showed that the adding GO was inserted the layer structure of LDH and the surface functional group of GO was immobilized in LDH well. GAT could be degraded completely after 45 min under the reaction conditions of pH 7.0, 38 mg L−1 GAT, 40 mg L−1 LDH/GO and 400 mg L−1 PMS. The removal of total organic carbon and defluorination reached 55.5% and 78.0% after 5 h reaction, respectively. Quenching tests suggested that the main radicals responsible for GAT degradation and mineralization was sulfate radical (SO4−). The redox cycle made the catalysis of the LDH/GO composites work continuously. Compared with LDH + PMS system, the concentration of dissolved metals decreased 60.6%-74.3% at pH 3.0–11.0 in LDH/GO + PMS system. The reusability test indicates that LDH/GO has stable catalytic performance in removing PPCPs from wastewater.
Diabetes mellitus is a common chronic disease and a severe public health issue. The incidence trends for type 1 diabetes (TIDM) and type 2 diabetes (T2DM) have rarely been studied on a global scale. ...We aimed to determine the temporal and geographical trends of diabetes globally.
Data on diabetes mellitus, including incidence, prevalence from 1990 to 2017 were obtained from the 2017 Global Burden of Disease study. We calculated the estimated annual percentage changes (EAPCs) in age-standardized incidence rate (ASIR) of diabetes mellitus according to sex, region, and disease type.
The worldwide incident cases of diabetes mellitus has increased by 102.9% from 11,303,084 cases in 1990 to 22,935,630 cases in 2017 worldwide, while the ASIR increased from 234 /100,000 persons (95% UI, 219-249) to 285/100,000 persons (95% UI, 262-310) in this period EAPC = 0.87, 95% confidence interval (CI):0.79-0.96. The global ASIRs of T1DM and T2DM both demonstrated significant increase during 1990-2017, with EAPCs of 0.34 (95% CI,0.30-0.39) and 0.89 (95% CI,0.80-0.97), respectively. The ASIR trends also varied considerably by regions and countries. The increase in ASIR was greatest in high sociodemographic index regions (EAPC = 1.05, 95% CI:0.92-1.17) and lowest in low-SDI regions (EAPC = 0.79, 95% CI:0.71-0.88).
Both the number of incident cases and ASIR of diabetes mellitus increased significantly during 1990-2017 worldwide, but the temporal trends varied markedly across regions and countries.
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•Ciprofloxacin (CIP) is quickly degraded in UV/chlorine process.•CIP degradation in UV/chlorine process is affected by many anions and humic acid.•Hydrated electron, Cl, HO, and UV ...photolysis play key role in CIP degradation.•Degradation pathway of CIP in UV/chlorine process is proposed.
Ciprofloxacin (CIP) is a widely used third generation fluoroquinolone antibiotics, and has been often detected in wastewater treatment plants. Finding an effective way to remove them from wastewater is of great concern. Ultraviolet (UV)/chlorine advanced oxidation process (AOP) has many advantages in micropollutant removal. In this study, CIP degradation in UV/chlorine process was investigated. Only 41.2% of CIP was degraded by UV photolysis and 30.5% by dark chlorination in 30 min, while 98.5% of CIP was degraded by UV/chlorine process in 9 min. HCO3− had markedly inhibition, NO3− and SO42- had slight inhibition, and Cl− had a marginal inhibition on CIP degradation in UV/chlorine system. The degradation of CIP in UV/chlorine process was mainly attributed to the attack of reactive species. The relative contributions of hydrated electrons (eaq), hydroxyl radicals (HO), chlorine atoms (Cl), and UV photolysis were investigated. Under neutral condition in aqueous solution, CIP degradation had highest pseudo first-order reaction rate constant, in which eaq had the highest contribution, followed by Cl, HO, and UV photolysis. The intermediates and byproducts were identified and the degradation pathway was proposed. The total organic chlorine (TOCl) and biotoxicity were further assessed. CIP and natural organic matters (NOMs) were removed efficiently in real water. UV/chlorine showed the potential for the wastewater treatment containing CIP.
The record-breaking mei-yu in the Yangtze-Huaihe River valley (YHRV) in 2020 was characterized by an early onset, a delayed retreat, a long duration, a wide meridional rainbelt, abundant ...precipitation, and frequent heavy rainstorm processes. It is noted that the East Asian monsoon circulation system presented a significant quasi-biweekly oscillation (QBWO) during the mei-yu season of 2020 that was associated with the onset and retreat of mei-yu, a northward shift and stagnation of the rainbelt, and the occurrence and persistence of heavy rainstorm processes. Correspondingly, during the mei-yu season, the monsoon circulation subsystems, including the western Pacific subtropical high (WPSH), the upper-level East Asian westerly jet, and the low-level southwesterly jet, experienced periodic oscillations linked with the QBWO. Most notably, the repeated establishment of a large southerly center, with relatively stable latitude, led to moisture convergence and ascent which was observed to develop repeatedly. This was accompanied by a long-term duration of the mei-yu rainfall in the YHRV and frequent occurrences of rainstorm processes. Moreover, two blocking highs were present in the middle to high latitudes over Eurasia, and a trough along the East Asian coast was also active, which allowed cold air intrusions to move southward through the northwestern and/or northeastern paths. The cold air frequently merged with the warm and moist air from the low latitudes resulting in low-level convergence over the YHRV. The persistent warming in the tropical Indian Ocean is found to be an important external contributor to an EAP/PJ-like teleconnection pattern over East Asia along with an intensified and southerly displaced WPSH, which was observed to be favorable for excessive rainfall over YHRV.
Roxarsone, an extensively used organoarsenical feed additive, is often pooled in livestock wastewater. Sulfate exists ubiquitously in livestock wastewater and is capable for arsenic remediation. ...However, little is known about impacts of sulfate on roxarsone biotransformation during anaerobic digestion of livestock wastewater. In this study, the biodegradation of 5.0 mg L−1 roxarsone, and the accumulation and volatilization of the generated arsenical metabolites in a sulfate-spiked upflow anaerobic granular blanket reactor were investigated. Based on the analysis of degradation products, the nitro and arsenate groups of roxarsone were successively reduced to amino and arsenite groups before the C–As bond cleavage. Effluent arsenic concentration was ∼0.75 mg L−1, of which 82.9–98.5% were organoarsenicals. The maximum arsenic volatilization rate reached 32.6 μg-As kg−1-VS d−1. Adding 5.0 mg L−1 sulfate enabled 66.7% and 45.9% decrease in inorganic arsenic concentration and arsenic volatilization rate, respectively. Arsenic content in the anaerobic granular sludge (AGS) was accumulated to 1250 mg kg−1 within 420 days. Based on the results of FESEM-EDS and XPS, sulfate addition induced arsenic precipitation in the AGS through the formation of orpiment. Arsenic in the effluent, biogas and AGS accounted for 52.9%, 0.01% and 47.1% of the influent arsenic when the reactor operated stably. The findings from this study suggest that sulfate has effectively regulatory effects on arsenic immobilization and volatilization during anaerobic digestion of organoarsenic-contaminated livestock wastewater.
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•A degradation pathway of roxarsone into inorganic arsenic (As) was proposed.•SO42− addition enabled a 66.7% decrease in inorganic As concentration.•As content in the sludge increased from ∼5 to 1250 mg kg−1 within 420 days.•SO42− addition triggered a 45.9% decrease in As volatilization rate.•Most of influent As ended up in the effluent and sludge, with 0.01% volatilized.
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•Thiamphenicol degradation in UV/H2O2 and UV/PS processes was compared.•Thiamphenicol degradation followed the pseudo-first-order kinetics pattern well.•Thiamphenicol degradation was ...affected by solution pH, anions and HA.•UV/PS process was more efficient in degrading and mineralizing thiamphenicol.•Degradation pathways were proposed based on the result of LC–TOF-MS analysis.
Thiamphenicol (TAP) has been widely used in aquaculture to prevent bacterial diseases. However, this drug exhibits toxic side effects on the haemopoietic system. The removal of residual TAP in wastewater in advanced oxidation processes (AOPs) was rarely reported before. In this study, degradation of TAP in aqueous solution by UV alone, UV/H2O2 and UV/PS processes was investigated. The results showed that UV/H2O2 and UV/PS significantly enhanced the degradation compared to UV alone. The TAP degradation followed a pseudo-first-order kinetics pattern well. The kobs declined with the increase of the initial TAP concentration, and increased with increasing oxidant dosage. The TAP degradation with UV/H2O2 process was favorable under neutral and acidic conditions, and with UV/PS process was favorable under acidic and alkaline conditions. HCO3− markedly inhibited the degradation with the both processes, NO3− had a slight inhibition on the degradation in UV/H2O2 system, and Cl− significantly enhanced the degradation with UV/PS process. HA markedly inhibited the degradation with the both processes. SO4− played the main role in the TAP degradation by UV/PS process. When TAP was completely degraded, only part of TAP was mineralized with UV/H2O2 process, and was totally mineralized with UV/PS process. The possible degradation pathways were proposed based on the intermediate products obtained by LC-TOF-MS analysis. The electrical energy per order (EE/O) analysis showed that UV/PS process was a less energy consumption process. The results from this study revealed that UV/PS process was a cost-effective process in the degradation of TAP.
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•Riboflavin-derivative as a photosensitizer was more stable than riboflavin.•Degradation of roxarsone to arsenate can reduce the mobility and environmental risk.•Roxarsone was ...photodegraded by riboflavin-derivative.•1O2, O2− and excited riboflavin-derivative played a key role in the degradation.
Roxarsone (ROX) is a typical organoarsenic feed additive, and most of ROX is excreted unchanged in manure and wastewater. The stability and mobility of ROX result in the environmental risk of arsenic contamination spreading. The degradation of ROX to arsenate (As(V)) can reduce the mobility and environmental risk. Riboflavin is a photosensitizer and can catalyze ROX to As(V), but it is not stable in water environment. In this study, riboflavin-derivative 2′,3′,4′,5′-tetraacetylriboflavin (RTA) was used to replace riboflavin as photosensitizer. The possibility of ROX photodegradation using riboflavin-derivative (RTA) as photosensitizer was investigated. The results showed that RTA was more stable than riboflavin in water environment. ROX was degraded to arsenite (As(III)) by RTA in 90 min under simulated sunlight irradiation and 50 min under natural sunlight irradiation, and further to As(V). The degradation was inhibited under acidic or alkaline pH conditions, while was favorable under neutral pH conditions. The mechanisms of ROX degradation by RTA were further explored. 1O2, O2− and excited RTA played important role in the RTA-sensitized ROX photodegradation. The photocatalytic degradation of roxarsone by RTA can reduce mobility of arsenic and the environmental risk caused by organoarsenicals.
The disposal of food waste is a challenge for waste management while denitrification is often limited by the shortage of carbon source in wastewater treatment. Food waste has the potential to be used ...as carbon source for advanced nitrogen removal of secondary effluent. In this study, fermentation liquid production from food waste and the denitrification performance of simulated secondary effluent with fermentation liquid as carbon source in sequencing batch reactors, and the characteristics of the effluent after denitrification were investigated. The results indicated that the total chemical oxygen demand concentration reached 54.5 ± 4.7 g/L in the fermentation liquid with the ratio of total chemical oxygen demand/total nitrogen of 174.0 ± 24.0. Carbohydrate, lactate, volatile fatty acids were the main components. For the denitrification, the total nitrogen removal efficiencies of using fermentation liquid and sodium acetate as carbon source were 87.4 ± 7.2% and 95.0 ± 4.5%, respectively. There was no obvious difference in characteristics of the effluents (such as total chemical oxygen demand, dissolved organic carbon and specific UV absorbance at 254 nm) between the two carbon sources, confirming the feasibility of using fermentation liquid for advanced nitrogen removal.
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•The carbon source concentration reached 54.5 ± 4.7 g/L in the fermentation liquid.•Carbohydrate, lactate, volatile fatty acids were the main components.•Total nitrogen removal efficiency of using fermentation liquid were 87.4 ± 7.2%.•The characteristics of the effluents between the two carbon sources were similar.
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