Biodegradation of erythromycin by Delftia lacustris RJJ-61 and characterization of its erythromycin esterase.

The residual erythromycin in fermentation waste can pollute the environment and threaten human health. However, there are no effective approaches to remedy this issue. In this study, an erythromycin-degrading bacterium named RJJ-61 was isolated and identified as a strain of Delftia lacustris based on morphological and phylogenetic analyses. The degradation ability of this strain was also evaluated; it could degrade 45.18% of erythromycin at 35°C in 120 h. Furthermore, the key degradation gene ereA was cloned from strain RJJ-61 and expressed in Escherichia coli BL21; the molecular weight of the expressed protein was ~45 kDa. The enzyme activity of EreA was 108.0 mU ml-1 at 35°C and pH 7.0. Finally, the EreA protein was used to degrade erythromycin from mycelial dregs and 50% diluted solution, and the removal rates in them were 41.42% and 69.78%, respectively. In summary, D. lacustris RJJ-61 is a novel erythromycin-degrading strain that has great potential to remove erythromycin pollutants from the environment.

Anti-fouling PVDF membranes incorporating photocatalytic biochar-TiO2 composite for lignin recycle.

In this study, a photocatalytic biochar-TiO2 (C-Ti) composite was prepared using lignin as carbon precursor, and blended with PVDF polymer to fabricate PVDF/C-Ti MMMs via non-solvent induced phase inversion. The prepared membrane demonstrates both 1.5 times higher initial and recovered fluxes than the similarly prepared PVDF/TiO2 membrane, suggesting the C-Ti composite can help maintain higher photodegradation efficiency and better anti-fouling performance. In addition, the comparison of PVDF/C-Ti membrane against pristine PVDF membrane show that the reversible fouling and photodegradation reversible fouling of BSA increased from 10.1% to 6.4%-35.1% and 26.6%, respectively. And the FRR of PVDF/C-Ti membrane was 62.12%, 1.8 times that of PVDF membrane. The PVDF/C-Ti membrane was also applied for lignin separation, where the rejection to sodium lignin sulfonate was maintained at about 75%, and the flux recovery ratio after UV irradiation reached 90%. The demonstrated the advantages of PVDF/C-Ti membrane in photocatalytic degradation and antifouling performance.

Magnetized algae catalyst by endogenous N to effectively trigger peroxodisulfate activation for ultrafast degraded sulfathiazole: Radical evolution and electron transfer.

An innovative Fe-N co-coupled catalyst MN-2 was prepared from waste spirulina by co-pyrolysis as a highly active carbon-based catalyst for the activation of peroxydisulfate (PDS) for the degradation of sulfathiazole (ST). The protein-rich raw material Spirulina provided sufficient N during the pyrolysis process, thus achieving N doping without an additional nitrogen source, optimizing the interlayer structure of the biochar material and effectively inhibiting the leaching of the ligand metal Fe. MN-2 showed highly efficient catalytic activity for peroxydisulfate (PDS), with a degradation efficiency of 100% for ST within 30 min and a kinetic constant (kobs) reached 0.306 min-1, benefiting from the excellent adsorption ability of MN-2 forming MN-2-PDS* complexes and the electron transfer process generated by Fe3+ and Fe2+ cycling, oxygen-containing functional groups. The effects of PDS dosage, initial pH and coexisting anions on the oxidation process were also investigated. Free radical quenching, electron paramagnetic resonance and electrochemical measurements were employed to explain the hydroxyl (·OH) and sulfate (SO4·-) as the dominant active species and the electron transfer effect on the removal of ST. MN-2 maintained a ST removal rate of 84% after four recycling experiments, showing a high reusability performance. This work provides a simple way to prepare magnetized N-doped biochar, a novel catalyst (MN-2) for efficient activation of PDS for ST degradation, and a feasible method for removing sulfanilamide antibiotics in water environment.

Environmental factors induced macrolide resistance genes in composts consisting of erythromycin fermentation residue, cattle manure, and maize straw.

With the growing concerns about antibiotic resistance, it is more and more important to prevent the environmental pollution caused by antibiotic fermentation residues. In this study, composted erythromycin fermentation residue (EFR) with the mixture of cattle manure and maize straw at ratios of 0:10 (CK), 1:10 (T1), and 3:10 (T2) explores the effects on physicochemical characteristics, mobile genetic elements (MGEs), and antibiotic resistance genes (ARGs). Results reflected that the addition of EFR reduced the carbon/nitrogen ratio of each compost and improved the piles' temperature, which promoted the composting process. However, the contents of Na+, SO42-, and erythromycin were also significantly increased. After 30 days of composting, the degradation rates of erythromycin in CK, T1, and T2 were 72.7%, 20.3%, and 37.1%, respectively. Meanwhile, the total positive rates for 26 detected ARGs in T1 and T2 were 65.4%, whereas that of CK was only 23.1%. Further analysis revealed that ARGs responsible for ribosomal protection, such as ermF, ermT, and erm(35), dominated the composts of T1 and T2, and most were correlated with IS613, electrical conductivity (EC), nitrogen, and Zn2+. Above all, adding EFR helps to improve the nutritional value of composts, but the risks in soil salinization and ARG enrichment caused by high EC and erythromycin content should be further investigated and eliminated.

Designing Multi-Stage 2 A/O-MBR Processes for a Higher Removal Rate of Pollution in Wastewater.

Multi-stage A/O-MBR processes were designed to improve wastewater treatment efficiency; three different designs were carried out and compared in this study. The 2(A/O)-MBR process, i.e., with two sets of anoxic/oxic tanks in series, showed better effluent quality than A/O-MBR and 3(A/O)-MBR processes. The removal rates of COD, NH4+-N, TP and TN were 95.29%, 89.47%, 83.55% and 78.58%, respectively, complying satisfactorily with China's urban sewage treatment plant pollutant discharge standards. In terms of membrane fouling, the 3(A/O)-MBR process demonstrated the lowest fouling propensity. The microbial community structure in each bioreaction tank was analyzed, the results from which matched with the process efficiency and fouling behavior.

Research Priorities and Trends on Bioenergy: Insights from Bibliometric Analysis.

Replacing fossil fuels with bioenergy is crucial to achieving sustainable development and carbon neutrality. To determine the priorities and developing trends of bioenergy technology, related publications from 2000 to 2020 were analyzed using bibliometric method. Results demonstrated that the number of publications on bioenergy increased rapidly since 2005, and the average growth rate from 2005 to 2011 reached a maximum of 20% per year. In terms of publication quantity, impact, and international collaboration, the USA had been leading the research of bioenergy technology, followed by China and European countries. Co-occurrence analysis using author keywords identified six clusters about this topic, which are "biodiesel and transesterification", "biogas and anaerobic digestion", "bioethanol and fermentation", "bio-oil and pyrolysis", "microalgae and lipid", and "biohydrogen and gasification or dark fermentation". Among the six clusters, three of them relate to liquid biofuel, attributing that the liquid products of biomass are exceptional alternatives to fossil fuels for heavy transportation and aviation. Lignocellulose and microalgae were identified as the most promising raw materials, and pretreating technologies and efficient catalysts have received special attention. The sharp increase of "pyrolysis" and "gasification" from 2011 to 2020 suggested that those technologies about thermochemical conversion have been well studied in recent years. Some new research trends, such as applying nanoparticles in transesterification, and hydrothermal liquefaction in producing bio-oil from microalgae, will get a breakthrough in the coming years.

Preparation and SO2 capture kinetics of a DeSOx coating for the desulfurization of exhaust emission.

Sulfur dioxide (SO2) is an extremely harmful pollutant in diesel engine exhaust fumes, which must be controlled and removed effectively. In order to better integrate desulfurization materials into diesel exhaust systems, a new desulfurization powder coating (DeSOx coating) was prepared. The SO2 capture performance and kinetics of the DeSOx coating were subsequently studied. This study used a fixed-bed reactor to test the DeSOx coating SO2 capture performance and conduct kinetic analysis at various temperatures and gas flows. The analysis obtained the kinetic parameters of the activation energy and Arrhenius constant, with the derived rate control equations, under isothermal conditions. The DeSOx coating and filter which were prepared using metal oxide powders, SiO2 colloidal sol, and additives, exhibited an enhanced SO2 capture performance. In this experiment, an MnO2/SiO2/LiOH coating had the best SO2 removal rate and capture capacity at 400 °C. Under a reaction space velocity of 10700 h-1, the MnO2/SiO2/LiOH coating SO2 removal rate was 100% within the first hour of reaction. Under a reaction space velocity of 32000 h-1, the MnO2/SiO2/LiOH coating SO2 capture capacity was 132.7 mgSO2/gmaterial during the second hour of reaction. The SO2 capture conversion rate of the DeSOx coating and filter follows the second-order kinetic mechanism model. For the MnO2/SiO2/LiOH coating, the Arrhenius equation gives an activation energy of 4952 J/mol and the Arrhenius natural logarithmic constant is 8.969 s-1. For the MnO2/SiO2/LiOH filter, the activation energy of the rate constant is 214 J/mol, and the Arrhenius natural logarithmic constant is 3.744 s-1. Therefore, the desulfurization coating is an effective way to remove SO2 pollutants from diesel exhaust gases.

Effects of pH and Metal Ions on the Hydrothermal Treatment of Penicillin: Kinetic, Pathway, and Antibacterial Activity.

Antibiotic residues lead to the risk of resistance gene enrichment, which is the main reason why penicillin mycelial dreg (PMD) is defined as hazardous waste. Hydrothermal treatment (HT) is an effective method to treat penicillin mycelial dreg, but the degradation mechanism of penicillin is unclear. In the study, we researched the effects of pH (4-10) at 80-100 °C and metal ions (Mn2+, Fe2+, Cu2+, and Zn2+) at several concentrations on the HT of penicillin, identified the degradation products (DPs) under different conditions, and evaluated the antibacterial activity of hydrothermally treated samples. The results show that penicillin degradation kinetics highly consistent with pseudo-first-order model (R2 = 0.9447-0.9999). The degradation rates (k) at pH = 4, 7, and 10 were 0.1603, 0.0039, and 0.0485 min-1, indicating acidic conditions were more conducive to penicillin degradation. Among the four tested metal ions, Zn2+ had the most significant catalytic effect. Adding 5 mg·L-1 Zn2+ caused 100% degradation rate at pH = 7 after HT for 60 min. Six degradation products (DPs) with low mass-to-charge (m/z ≤ 335) were detected under acidic condition. However, only two and three DPs were observed in the samples catalyzed by Zn2+ and alkali, respectively, and penilloic acid (m/z = 309) was the main DPs under these conditions. Furthermore, no antibacterial activity to Bacillus pumilus was detected in the medium with up to 50% addition of the treated samples under acidic condition. Even though acid, alkali, and some metal ions can improve the degradation ability of penicillin, it was found that the most effective way for removing its anti-bacterial activity was under the acidic condition. Therefore, resistance residue indicates the amount of additive in the process of resource utilization, and avoids the enrichment of resistance genes.

Determinizing the contributions of human activities and climate change on greening in the Beijing-Tianjin-Hebei Region, China.

China accounts for 25% of the global greening. There are temporal and spatial differences of China's greening and intrinsic driving forces. Thus, it is crucial to determinize the contributions of human activities and climate change on greening at region scale. The Beijing-Tianjin-Hebei Region (BTHR) is one of the most active areas with human activities in China. It is necessary to explore negative or positive impacts of human activities on the regional greening or browning under climate change. A time series of annual vegetation coverage from satellite data was selected to quantify regional greening in the BTHR from 2000 to 2019 and their responses to climate change and human activities. Results showed generally widespread greening over the last 20 years at an average increased rate of 0.036 decade-1 in vegetation coverage (P < 0.01). Overall warmer and wetter climate across the BTHR were positively correlated with regional greening. The positive effects of human activities on greening accounted for 48.4% of the BTHR, especially the benefits of ecological restoration projects and the agricultural activities. Increases in vegetation coverage had resulted from the combined effects of climate change and human activities. Climate change had a stronger influence on vegetation coverage than human activities. Contributions of climate change to greening and browning was about 74.1% and < 20%, respectively. The decrease in vegetation coverage was mainly the results of the inhibition of human activities. More detailed socioeconomic and anthropogenic datasets are required for further analysis. Further research consideration would focus on the nonlinear responses of vegetation to climate change.

Fabrication of Carbon-Alumina Composites via Catalytic Pyrolysis of Pine Sawdust on Aluminum Dross for Cr(VI) Removal.

Carbon-alumina composites are prepared for the efficient removal of Cr(VI) from wastewater. Pristine and acid-treated alumina dross (AD and AAD) are copyrolyzed with pine sawdust to form the respective composites, ADPC and AADPC. Excellent absorption properties with Cr(VI) removal efficiency of 95.08% are demonstrated at 60 °C for an initial concentration of 6 µg/mL. The composites combine the merits of char, which provides a high surface-to-volume ratio with abundant functional groups on the surface, and alumina, which provides metal ions for coprecipitation. Carbon structures of pine, char, and composite were analyzed semiquantitatively using 13C NMR by a curve-fitting method. Cr(VI) adsorption is accurately described with chemisorption by the Langmuir isotherm model and a pseudo-second-order kinetic model. The results show that AADPC has more alcohol hydroxyl groups substituted to glucosyl units in amorphous cellulose assigned to the peak at 80 ppm and hemicellulose assigned to peaks at 97 and 101 ppm. Also, it has more phenolic groups in lignin distributed at syringyl units assigned to peaks at 129 and 146 ppm. These oxygen-containing functional groups have a significant influence on Cr(VI) adsorption and reduction to Cr(III) governed by the mechanisms of diffusion, adsorption, complexation, reduction, and coprecipitation. The results of this work provide a new direction for the reuse of biomass and industrial solid wastes to fabricate higher value-added products, i.e., adsorption materials for Cr(VI) removal and stabilization.

Calcium-Loaded Municipal Sludge-Biochar as an Efficient and Stable Catalyst for Biodiesel Production from Vegetable Oil.

In this contribution, biochar from municipal sludge was used as a novel matrix for the synthesis of a series of calcium-based heterogeneous catalysts toward biodiesel production. Their catalytic activity was investigated in terms of catalyst loading and calcination temperature during preparation, in addition to the transesterification parameters including the methanol/oil molar ratio, reaction time, and catalyst amount. The highest biodiesel yield up to 93.77% was achieved with the 30Ca/A-SBC-700, and it maintained as high as 84.9% even after 10 cycles of a consecutively alternating catalysis and regeneration process. It was revealed that the porous municipal sludge biochar and autologous SiO2 were accountable for the superior stability of the present catalyst. This work may provide a new path to value-added valorization of sludge waste and also a renewable and efficient catalyst for biodiesel production at a low cost.