Cellulose-based aerogel derived N, B-co-doped porous biochar for high-performance CO2 capture and supercapacitor

The remarkable characteristics of porous biochar have generated significant interest in various fields, such as CO2 capture and supercapacitors. The modification of aerogel-derived porous biochar through activation and heteroatomic doping can effectively enhance CO2 adsorption and improve supercapacitor performance. In this study, a novel N, B-co-doped porous biochar (NBCPB) was synthesized by carbonating and activating the N, B dual-doped cellulose aerogel. N and B atoms were doped in-situ using a modified alkali-urea method. The potassium citrate was served as both an activator and a salt template to facilitate the formation of a well-developed nanostructure. The optimized NBCPB-650-1 (where 650 corresponded to activation temperature and 1 represented mass ratio of potassium citrate activator to carbonized NBCPB-400 precursor) displayed the largest micropore volume of 0.40 cm3·g-1 and a high specific surface area of 891 m2·g-1, which contributed to an excellent CO2 adsorption capacity of 4.19 mmol·g-1 at 100 kPa and 25 °C, a high CO2/N2 selectivity, and exceptional reusability (retained >97.5 % after 10 adsorption-desorption cycles). Additionally, the NBCPB-650-1 electrode also delivered a high capacitance of 220.9 F·g-1 at 1 A·g-1. Notably, the symmetrical NBCPB-650-1 supercapacitor exhibited a high energy density of 9 Wh·kg-1 at the power density of 100 W·kg-1. This study not only presents the potential application of NBCPB-650-1 material in CO2 capture and electrochemical energy storage, but also offers a new insight into easy-to-scale production of heteroatomic-modified porous biochar.

Changes of MRGs and ARGs in Acinetobacter sp. SL-1 used for treatment of Cr(VI)-contaminated wastewater with waste molasses as carbon source

Antibiotic resistance genes (ARGs) may be synergistic selected during bio-treatment of chromium-containing wastewater and causing environmental risks through horizontal transfer. This research explored the impact of self-screening bacterium Acinetobacter sp. SL-1 on the treatment of chromium-containing wastewater under varying environmental conditions. The findings indicated that the optimal Cr(VI) removal conditions were an anaerobic environment, 30 °C temperature, 5 g/L waste molasses, 100 mg/L Cr(VI), pH = 7, and a reaction time of 168 h. Under these conditions, the removal of Cr(VI) reached 99.10 %, however, it also developed cross-resistance to tetracycline, gentamicin, clarithromycin, ofloxacin following exposure to Cr(VI). When decrease Cr(VI) concentration to 50 mg/L at pH of 9 with waste molasses as carbon source, the expression of ARGs was down regulated, which decreased the horizontal transfer possibility of ARGs and minimized the potential environmental pollution risk caused by ARGs. The study ultimately emphasized that the treatment of chromium-containing wastewater with waste molasses in conjunction with SL-1 not only effectively eliminates hexavalent chromium but also mitigates the risk of environmental pollution.

Synergistic preparation and application in PCU of α-calcium sulfate hemihydrate whiskers from phosphogypsum and electrolytic manganese residue

The α-calcium sulfate hemihydrate whiskers (α-CSHWs) were first prepared using phosphogypsum (PG) and electrolytic manganese residue (EMR) as raw materials for coating urea, demonstrating excellent controlled-release properties. The effects of different reaction conditions on α-CSHWs, achieved by optimizing the reaction time, the concentrations of NH4+, Mn2+, and other factors, were discussed. Results showed that when the EMR content was 25 wt%, the reaction temperature was 100 °C, and the reaction time was 3 h, α-CSHWs with a length-to-diameter ratio of 39 were obtained. Through experiments and density functional theory (DFT), the mechanism of α-CSHWs preparation was elucidated. The results show that the addition of EMR reduces the content of impurity ions PO43- and F- in PG while introducing NH4+ and Mn2+. Interestingly, both NH4+ and Mn2+ can reduce the nucleation time of α-CSHWs, while PO43-, Mn2+, and F- are more likely to adsorb on the (0 0 6) crystal plane of α-CSHWs, NH4+ readily adsorbs on the (4 0 0) crystal plane. The controlled-release performance of modified α-CSHWs incorporated into polyurethane-coated urea (PCU) was investigated, and it was found that the addition of Mα significantly prolonged the nutrient release period, with the period extending up to 116 days for coatings of 5wt% and above. This work not only enhances the efficiency of PG and EMR utilization but also serves as a reference for the straightforward synthesis and application of α-CSHWs.

Janus Zn-IV-VI: Robust Photocatalysts with Enhanced Built-In Electric Fields and Strain-Regulation Capability for Water Splitting

The use of 2D materials to produce hydrogen (H2 ) fuel via photocatalytic water splitting has been intensively studied. However, the simultaneous fulfillment of the three essential requirements-high photon utilization, rapid carrier transfer, and low-barrier redox reactions-for wide-pH-range production of H2 still poses a significant challenge with no additional modulation. By employing the first-principles calculations, it has been observed that the Janus ZnXY2 structures (X = Si/Ge/Sn, Y = S/Se/Te) exhibit significantly enhanced built-in electric fields (0.20-0.36 eV Å-1 ), which address the limitations intrinsically. Compared to conventional Janus membranes, the ductile ZnSnSe2 and ZnSnTe2 monolayers have stronger regulation of electric fields, resulting in improved electron mobility and excitonic nature (Ebinding = 0.50/0.35 eV). Both monolayers exhibit lower energy barriers of hydrogen evolution reaction (HER, 0.98/0.86 eV, pH = 7) and resistance to photocorrosion across pH 0-7. Furthermore, the 1% tensile strain can further boost visible light utilization and intermediate absorption. The optimal AC-type bilayer stacking configuration is conducive to enhancing electric fields for photocatalysis. Overall, Janus ZnXY2 membranes overcome the major challenges faced by conventional 2D photocatalysts via intrinsic polarization and external amelioration, enabling efficient and controllable photocatalysis without the need for doping or heterojunctions.

[Comparison of the impact of orthodontic treatment on pulp volume in adolescents and adults]

Objective: To compare the impact of orthodontic treatment on pulp volume in adolescents and adults. Methods: Cone-beam CT data of 62 patients undergoing orthodontic treatment at the Department of Orthodontics, Stomatological Hospital of Chongqing Medical University, from January 2019 to March 2022 were collected. Patients were divided into two age groups (31 patients in each group): adolescent group (aged 13-17, 17 males and 14 females) and adult group (aged 21-25, 12 males and 19 females). Pre-and post-treatment reconstructions of the pulp and dental tissues of upper first molars (UM1) and lower central incisors (L1) were performed. Measurements included pulp volume for UM1 (UM1 P) and L1 (L1 P), pulp chamber volume (UM1 PC) and root canal volume (UM1 RC) for UM1, root length for L1 (L1 RL), and mesiobuccal root length for UM1 (UM1 RL), as well as chamber heights at specific landmarks [the lengths from the central fossa fusion site to the roof of the pulp chamber (H1), the floor of the pulp chamber (H2), the nearest point of root divergence as well as crown-root bifurcation (H3), the farthest point of root divergence (H4), and the pulp chamber height (H5)] in UM1. Changes in these indices were calculated and analyzed using paired and independent sample t-tests for within-group and between-group differences, respectively. Pearson correlation was used to assess potential associations among H5, root length, and pulp volume changes. Results: Before and after orthodontic treatment, no significant difference was observed in the adult group for L1 P (t=-0.03, P=0.975), while significant differences were noted for UM1 P, UM1 PC, and UM1 RC (t=9.98, P<0.001; t=9.04, P<0.001; t=6.69, P<0.001). In the adolescent group, significant differences were found for both L1 P and UM1 P (t=2.25, P=0.029; t=6.30, P<0.001). After orthodontic treatment, the absolute value changes of UM1 P, UM1 PC, and L1 P in the adolescent group were (19.75±9.58), (15.07±7.65) and (1.89±6.29) mm3, respectively, and in the adult group were (13.33±9.41), (9.16±7.05) and (0.02±4.66) mm3, respectively (t=3.77, P<0.001; t=4.48, P<0.001; t=2.34, P=0.048). There was no significant absolute difference in the amount of UM1 RC between the two groups after orthodontic treatment (t=0.86, P=0.391). Before and after orthodontic treatment, the absolute value changes of L1 RL, H1 and H5 in the adolescent group were (0.54±0.41), (0.38±0.27) and (0.71±0.33) mm, respectively, and the absolute value changes in the adult group were (0.78±0.62), (0.26±0.20) and (0.57±0.28) mm, respectively (t=-2.43, P=0.017; t=2.96, P=0.004; t=2.57, P=0.011). Whereas no significant differences were observed for UM1 RL, H2, H3, and H4 (t=-0.85, P=0.400; t=0.43, P=0.669; t=-0.50, P=0.619; t=1.46, P=0.148). Additionally, significant correlations were found between changes in H5 and UM1 RL with UM1 P (r=0.35, P<0.001; r=0.19, P=0.030), but not between Changes in L1 RL and L1 P (r=0.11, P>0.05). Conclusions: The effect of orthodontic treatment on pulp volume in adolescents and adults were different.

Effects of bed depths and the ratio of aerobic to anaerobic zone on the performance of horizontal subsurface flow macrophyte-assisted high-rate vermifilters treating synthetic brewery wastewater

Effects of total vermibed depth, as well as the ratio of aerobic (the unsubmerged) to anaerobic (the submerged) zone on the performance of the horizontal subsurface flow macrophyte-assisted vermifilters (HSSF-MAVFs) treating synthetic brewery wastewater at a higher hydraulic loading rate (HLR), were investigated for the first time. Results showed that the HSSF-MAVF with a 50 cm total and 18 cm submerged vermibed depth yielded the optimum removal of the pollutants, ensuring a (91.2 ± 1.7)%, (81.8 ± 1.9)%, (67.4 ± 3.9)%, and (63.1 ± 2.3)% removal of chemical oxygen demand (COD), ammonium N (NH4 + -N), total N (TN), and organic N, respectively, whereas there was an increase of (142 ± 6.3)% in the effluent nitrate-N (NO3 - -N) than that in the influent. At the optimum condition, the effluent concentrations of all the pollutants including COD, NH4 + -N, NO3 - -N, TN, and organic N were well below the surface water discharge standards specified by the Central Pollution Control Board (CPCB), and thus, the effluent of the HSSF-MAVF could be safely discharged into the surface water bodies. PRACTITIONER POINTS: Total vermibed depth of HSSF-MAVFs was optimized for organic and nitrogen removal. HSSF-MAVFs were subjected to the higher HLR of synthetic brewery wastewater. Removal of COD and NH4 + -N was decreased with the increase in submerged bed depth. Removal of organic N and TN was increased with the increase in submerged bed depth. Total/unsubmerged bed depth had a positive impact on the organic and N removal.

Enhancing degradation of organic matter in microbial electrolytic cells coupled with anaerobic digestion (MEC-AD) systems by carbon-based materials

Currently, little information is available on relative contributions among biochar (BC), activated carbon (AC), magnetic BC (MBC), and magnetic AC (MAC) to enhance the effectiveness of a microbial electrolytic cells coupled with anaerobic digestion (MEC-AD) system and the impact of carbon-based materials on microbial community. In this study, six anaerobic reactors were constructed to demonstrate the effects of different carbon-based materials on organic matter elimination in the MEC-AD system. Remarkably, the reactor containing MBC exhibited a significant increase in organic removal, achieving 95.0 % chemical oxygen demand (COD) eradication. Additionally, the MBC-added MEC-AD reactor yields acetic acid at a rate 2.9 times higher than that of the BC-added reactor. Electrical stimulation enriched electro-producing bacteria such as Pseudomonas (18.1 %) and Gordonia (6.8 %), which were further promoted by the addition of MBC, indicating that the microbial communities cultivated with the MBC could provide the necessary microbiome for the MEC.

Spatiotemporal-based automated inundation mapping of Ramsar wetlands using Google Earth Engine

Wetlands are one of the most critical components of an ecosystem, supporting many ecological niches and a rich diversity of flora and fauna. The ecological significance of these sites makes it imperative to study the changes in their inundation extent and propose necessary measures for their conservation. This study analyzes all 64 Ramsar sites in China based on their inundation patterns using Landsat imagery from 1991 to 2020. Annual composites were generated using the short-wave infrared thresholding technique from June to September to create inundation maps. The analysis was carried out on each Ramsar site individually to account for its typical behavior due to regional geographical and climatic conditions. The results of the inundation analysis for each site were subjected to the Mann-Kendall test to determine their trends. The analysis showed that 8 sites exhibited a significantly decreasing trend, while 14 sites displayed a significantly increasing trend. The accuracy of the analysis ranged from a minimum of 72.0% for Hubei Wang Lake to a maximum of 98.0% for Zhangye Heihe Wetland National Nature Reserve. The average overall accuracy of the sites was found to be 90.0%. The findings emphasize the necessity for conservation strategies and policies for Ramsar sites.

Ti-doped iron phosphide nanoarrays grown on carbon cloth as a self-supported electrode for enhanced electrocatalytic nitrogen reduction

The electrocatalytic nitrogen reduction reaction (eNRR) has been widely recognized as a promising method for green ammonia synthesis. However, the inert NN bond, inferior catalytic activity and small electrochemically active area impede its practical application. To circumvent these problems, we proposed self-supported Ti-doped iron phosphide (FeP) nanorod arrays grown on carbon cloth (Ti-FeP/CC) as an electrode for eNRR. The introduction of Ti doping sites regulated the electron structure of FeP, leading to electron migration from Fe to P, which facilitated N2-to-NH3 conversion. The as-prepared Ti-FeP/CC showed an enhancement of electrochemical surface area (ECSA), high electrical conductivity and well-exposed active sites. Ti-FeP/CC was capable of producing a high NH3 yield of 10.93 μg h-1 cm-2 and faradaic efficiency of 10.77% at an optimal voltage of -0.3 V (vs. RHE) in a 0.1 M Na2SO4 solution with excellent stability and durability during the eNRR process. This work not only presents a promising electrode material for eNRR, but also provides a new insight into rational heteroatom doping for electrocatalysis.

Remediation of arsenic contaminated water and soil using mechanically (ball milling) activated and pyrite-amended electrolytic manganese slag

With the development of industry, heavy metal (HM) pollution of soil has become an increasingly serious problem. Using passivators made of industrial by-products to immobilize HMs in contaminated soil is a promising in-situ remediation technology. In this study, the electrolytic manganese slag (EMS) was modified into a passivator (named M-EMS) by ball milling, and the effects of M-EMS on adsorption of As(V) in aquatic samples and on immobilization of As(V) and other HMs in soil samples were investigated under different conditions. Results demonstrated that M-EMS had a maximum As(V) adsorption capacity of 65.3 mg/g in the aquatic samples. Adding M-EMS to the soil reduced the leaching of As (from 657.2 to 319.8 μg/L) and other HMs after 30 d of incubation, reduced the bioavailability of As(V) and improved the quality and microbial activity of the soil. The mechanism for M-EMS to immobilize As in the soil are complex reactions, ion exchange reaction with As and electrostatic adsorption. This work provides new ideas of using waste residue matrix composites for sustainable remediation of Arsenic in the aquatic environment and soil.

Hierarchical Ni-Mn LDHs@CuC2O4 Nanosheet Arrays-Modified Copper Mesh: A Dual-Functional Material for Enhancing Oil/Water Separation and Supercapacitors

The pursuit of superhydrophilic materials with hierarchical structures has garnered significant attention across diverse application domains. In this study, we have successfully crafted Ni-Mn LDHs@CuC2O4 nanosheet arrays on a copper mesh (CM) through a synergistic process involving chemical oxidation and hydrothermal deposition. Initially, CuC2O4 nanosheets were synthesized on the copper mesh, closely followed by the growth of Ni-Mn LDHs nanosheets, culminating in the establishment of a multi-tiered surface architecture with exceptional superhydrophilicity and remarkable underwater superoleophobicity. The resultant Ni-Mn LDHs@CuC2O4 CM membrane showcased an unparalleled amalgamation of traits, including superhydrophilicity, underwater superoleophobicity, and the ability to harness photocatalytic forces for self-cleaning actions, making it an advanced oil-water separation membrane. The membrane's performance was impressive, manifesting in a remarkable water flux range (70 kL·m-2·h-1) and an efficient oil separation capability for both oil/water mixture and surfactant-stabilized emulsions (below 60 ppm). Moreover, the innate superhydrophilic characteristics of the membrane rendered it a prime candidate for deployment as a supercapacitor cathode material. Evidenced by a capacitance of 5080 mF·cm-2 at a current density of 6 mA cm-2 in a 6 M KOH electrolyte, the membrane's potential extended beyond oil-water separation. This work not only introduces a cutting-edge oil-water separation membrane and supercapacitor electrode but also offers a promising blueprint for the deliberate engineering of hierarchical structure arrays to cater to a spectrum of related applications.

A biomimetic beetle-like membrane with superoleophilic SiO2-induced oil coalescence on superhydrophilic CuC2O4 nanosheet arrays for effective O/W emulsion separation

It is highly attractive to develop highly efficient oil-in-water (O/W) emulsion separation technologies for promoting the oily wastewater treatment. Herein, a novel inversely Stenocara beetle-like hierarchical structure of superhydrophobic SiO₂ nanoparticle-decorated CuC₂O₄ nanosheet arrays were prepared on copper mesh membrane by bridging polydopamine (PDA) to make a SiO₂/PDA@CuC₂O₄ membrane for substantially enhanced separation of O/W emulsions. The superhydrophobic SiO₂ particles on the as-prepared SiO₂/PDA@CuC₂O₄ membranes were served as localized active sites to induce coalescence of small-size oil droplets in oil-in-water (O/W) emulsions. Such innovated membrane delivered outstanding demulsification ability of O/W emulsion with a high separation flux of 2.5 kL⋅m^-2⋅h^-1 and its filtrate's chemical oxygen demand (COD) being 30 and 100 mg⋅L^-1 for surfactant-free emulsion (SFE) and surfactant-stabilized emulsion (SSE), respectively, and also exhibited a good anti-fouling performance in cycling tests. The innovative design strategy developed in this work broadens the application of superwetting materials for oil-water separation and presents a promising prospect in practical oily wastewater treatment applications.

Efficient photo-adsorptive eradication of endocrine disrupting pesticides by chitosan co- decorated metal oxide bio-nanocomposite

Extensive consumption, toxicity and bioaccumulation of malathion (MLT) and lindane (γ-HCH) pesticides collectively attract the world's attention. Herein, the nanocomposite of chitosan wrapped NiO@ZnO was synthesized by a green methodology using Azadirachta indica leaves extract. Structural and morphological analysis of chitosan-NiO@ZnO showed hollow sphere-flake shaped image adsorbed on a solid chitosan surface with a large surface area of 73 m²g^-1. A decrease in values of lattice strain, dislocation density and crystallite size described the imperfection in crystal geometry and new peaks in FT-IR spectra at 698 cm^-1 and 448 cm^-1 of Ni-N and Zn-N, which respectively confirm the coupling. Chitosan-NiO@ZnO and individual nanoparticles (NiO and ZnO) were well-characterized and utilized for degradation MLT and γ-HCH under direct sunlight and dark conditions. The highest degradation of pesticides (above 94%) resulted with 2 mg L^-1 and 10 mg L^-1 of MLT (π-π) and γ-HCH, respectively with a 20 mg catalyst dose, and pH of ~ 7 under daylight exposure (5 h). Chitosan-NiO@ZnO substantially suppressed the half-life of the targeted pesticides (MLT: 0.48 h; HCH 0.51 h) and demonstrated the first-order kinetics with a high adsorption capacity, X_m (MLT: 14.5 mg g^-1 and γ-HCH 20.7 mg g^-1), which also confirmed the strong binding with the pesticides, followed by their conversion into safer and smaller metabolites. The charge separation mechanism was elucidated by UV reflectance and photoluminescence data. Hydroxyl radicals were most frequently responsible for the degradation of pesticides as confirmed by scavenger analysis. The synthesized green-nano photocatalyst showed high reusability (up to 10^th cycles), sensitivity and stability within the degradation process, presumably making it suitable for industrial applications.

Using innovative copper-loaded activated alumina (Cu/AA) as the catalyst for catalytic wet peroxidation (CWPO) of catechol

In this study, copper-loaded activated alumina (Cu/AA) was synthesized and used for the CWPO of catechol (a representative refractory organic pollutant). Various characterization techniques were deployed to characterize the catalysts, e.g., activated alumina (AA), as well as pristine and spent 1% Cu/AA. The innovative 1% Cu/AA catalyst exhibited good thermal stability up to 1173 K with a marginal weight loss of 13%. The Cu species were well dispersed on the activated alumina framework with no significant cluster formation. Typically, the average copper particle size of 5 nm was dispersed on the AA framework. Catechol removal was observed to be 92% with 87% mineralization at optimized conditions (initial catechol concentration = 200 mg/L, catalyst dose of 1% Cu/AA = 2 g/L; temperature = 323 K; pH = 6; and H₂O₂/catechol stoichiometric ratio = 0.5). The mineralization of catechol was analyzed using mass spectroscopy, with the associated mechanism has been elucidated. Results of this study indicated that synthesized catalyst has phenomenal advantages in terms of simple separation and high removal efficiency of catechol, suggesting the feasibility of employing Cu/AA as the effective catalyst for the CWPO of catechol.

The microbial synergy and response mechanisms of hydrolysis-acidification combined microbial electrolysis cell system with stainless-steel cathode for textile-dyeing wastewater treatment

Microbial electrolysis cell (MEC) has been existing problems such as poor applicability to real wastewater and lack of cost-effective electrode materials in the practical application of refractory wastewater. A hydrolysis-acidification combined MEC system (HAR-MECs) with four inexpensive stainless-steel and conventional carbon cloth cathodes for the treatment of real textile-dyeing wastewater, which was fully evaluated the technical feasibility in terms of parameter optimization, spectral analysis, succession and cooperative/competition effect of microbial. Results showed that the optimum performance was achieved with a 12 h hydraulic retention time (HRT) and an applied voltage of 0.7 V in the HAR-MEC system with a 100 μm aperture stainless-steel mesh cathode (SSM-100 μm), and the associated optimum BOD₅/COD improvement efficiency (74.75 ± 4.32 %) and current density (5.94 ± 0.03 A·m^-2) were increased by 30.36 % and 22.36 % compared to a conventional carbon cloth cathode. The optimal system had effective removal of refractory organics and produced small molecules by electrical stimulation. The HAR segment could greatly alleviate the imbalance between electron donors and electron acceptors in the real refractory wastewater and reduce the treatment difficulty of the MEC segment, while the MEC system improved wastewater biodegradability, amplified the positive and specific interactions between degraders, fermenters and electroactive bacteria due to the substrate complexity. The SSM-100 μm-based system constructed by phylogenetic molecular ecological network (pMEN) exhibited moderate complexity and significantly strong positive correlation between electroactive bacteria and fermenters. It is highly feasible to use HAR-MEC with inexpensive stainless-steel cathode for textile-dyeing wastewater treatment.

A feasibility investigation of a pilot-scale bioelectrochemical coupled anaerobic digestion system with centric electrode module for real membrane manufacturing wastewater treatment

The large-scale application of bioelectrochemical coupled anaerobic digestion (BES-AD) is limited by the matching of electrode configuration and the applicability of real wastewater. In this study, a pilot-scale BES-AD system with an effective system volume of 5 m³ and a 1 m³ volume of a carbon fiber brush electrode module was constructed and tested for treatment of the membrane manufacturing wastewater. The results showed that the BOD₅/COD of the wastewater was increased from 0.238 to 0.398 when the applied voltage was 0.9 V. The pollutants such as N, N-Dimethylacetamide and glycerol in wastewater were degraded significantly. The microorganisms in the electrode modules were spatially enriched. The fermenters (Norank_f__ML635J-40_aquatic_group, 6.55 %; unclassified_f__Propionibacteriaceae, 5.25 %) and degraders (Corynebacterium, 29.31 %) were mostly enriched at the bottom, while electroactive bacteria (Pseudomonas, 29.39 %, Geobacter, 7.86 %) were mostly enriched at the top. Combined with the economical construction and operation cost ($1708.8/m³ and $0.76/m³) of the BES-AD system.

Comparison of GHG emissions from open field burning and anaerobic digestion of rice straw

Rice straw (RS) has been burned in open fields in many countries, which is a growing environmental concern. Anaerobic digestion (AD) of RS is one of the sustainable alternatives to open burning of RS for converting the biomass into methane, carbon dioxide, and digestate for use as agricultural manure. The present study evaluates the RS generation, use patterns, and greenhouse gas emissions from open field burning and the AD of RS. Results indicate the AD of RS offers greater environmental benefits than that by RS open field burning. As a result of the open burning of RS in India emitted 592032.52 kg of CO2 equivalents/kg per year, whereas AD of RS contributes 122.86 kg of CO2 equivalents/kg per year. If RS were burned in an open field, its Global Warming Potential would be 493,873 times greater than that of AD. By minimizing GHG emissions and creating sustainable energy from waste, sustainable development, and circular economies are achieved.

Effects of different silicate minerals on silicon activation by Ochrobactium sp. T-07-B

As a kind of solid waste with a high silicon content, electrolytic manganese residue (EMR) can be utilized as silicon source by plants through bioleaching processes. EMR contains a variety of silicate minerals. In order to determine the source of available silicon in the bioleaching process of EMR, it is necessary to investigate the influence of silicate minerals in EMR on silicon-activating behavior of specific minerals. In this study, Ochrobactium sp. T-07-B was used to conduct bioleaching experiments on five kinds of silicate minerals with different structures (quartz, muscovite, biotite, olivine, and rhodonite); the growth of Ochrobactium sp. T-07-B, their acid- and polysaccharide-producing capacity, and evolution of surface morphology and structure of the silicate minerals in different systems were determined, so as to explore the silicon-activating capacity of Ochrobactium sp. T-07-B and the selectivity toward different minerals in the bioleaching process. Results showed that the effects of Ochrobactium sp. T-07-B for different silicate minerals were obviously different, and the sequence of silicon-activating efficiency from high to low was as follows: muscovite (65.84 mg·L^-1) > biotite (63.84 mg·L^-1) > olivine (55.76 mg·L^-1) > rhodonite (50.98 mg·L^-1) > quartz (23.63 mg·L^-1). Results of this study may be of guiding significance for the future research on the silicon-activating behavior of solid waste.

[Shandong hilly rural natural population cohort study: method and baseline characteristics of survey subjects]

Objective: To understand the study method and the baseline characteristics of the survey subjects of Shandong hilly rural natural population cohort study, and provide reference for the research of the prevalence and risk factors of common chronic and non-communicable diseases. Methods: Baseline survey, including questionnaire survey, physical examination, biochemical index examination and blood and saliva collection, was conducted in local residents aged 20-79 years in Kongcun and Xiaozhi townships of Pingyin county, Shandong province, from 2017 to 2019. Shandong hilly rural natural population cohort was established and main baseline characteristics of the study subjects were statistically analyzed. Results: A total of 10 296 study subjects aged 54.45 years were included in the study, in whom 40.6% were males. Among the study subjects, 88.3% had education level of junior high school or below, 62.1% were famers, and 90.7% were married. Smokers accounted for 45.6% of men and 0.9% of women, and drinkers accounted for 65.8% of men and 3.0% of women, respectively. The self-reported rates of hypertension, diabetes, coronary heart disease, stroke and tumors were 19.8%, 3.2%, 2.8%, 2.7% and 1.2%, respectively. Conclusion: The Shandong hilly rural cohort natural population study provided important evidence for assessing the risk for common chronic and non-communicable diseases and disease prevention and control in hilly rural areas.

Toxicity determination, pollution source delineation, and microbial diversity evaluation of PAHs-contaminated sediments for an urban river

The Feng-Sang River is a metropolitan river in Kaohsiung City, Taiwan. In this study, Feng-Sang River sediments were analyzed to investigate the distributions and sources of polycyclic aromatic hydrocarbons (PAHs). The Sediment Quality Guidelines (SQGs), potentially carcinogenic PAHs (TEQcarc ), and toxic equivalence quotient (TEQ) were applied to evaluate influences of PAHs on ecosystems and microbial diversities. Results indicate that PAHs concentrations varied between seasons and locations. The concentrations of ∑16 PAHs ranged from 73.6 to 603.8 ng/kg in dry seasons and from 2.3 to 199.3 ng/kg in wet seasons. This could be because of the flushing effect during wet seasons, which caused the movement and dilution of the PAH-contaminated sediments. Diagnostic ratio analysis infers that high PAHs levels were generated by combustion processes and vehicle traffic, and results from multivariate descriptive statistical analysis also demonstrate that the vehicular traffic pollution could be the major emission source of PAHs contamination. Comparisons of PAHs with SQGs indicate that PAHs concentrations in sediment were below the effects range low (ERL) values, and thus, the immediate threat to organisms might not be significant. The diagnostic ratio analyses are effective methods for PAH source appointment. The metagenomic assay results imply that sediments contained essential microbial species with eminent diversity. The detected PAH-degrading bacteria (Desulfatiglans, Dechloromonas, Sphingomonas, Methylobacterium, Rhodobacter, Clostridium, and Exiguobacterium) played a key role in PAHs biotransformation, and Dechloromonas and Rhodobacter had a higher relative abundance. Results of microbial diversity analyses indicate that the contaminated environment induced the changes of governing microbial groups in sediments. PRACTITIONER POINTS: Diagnostic ratio analyses are effective methods for PAHs source appointment. Microbial composition in sediments are highly affected by anthropogenic pollution. Combustion and vehicle traffic contribute to urban river sediments pollution by PAHs. Dechloromonas and Rhodobacter are dominant PAHs-degrading bacteria in sediments.

Response of microbial community to different land-use types, nutrients and heavy metals in urban river sediment

Nutrients and heavy metals (HM) in the sediment have an impact on microbial diversity and community structure. In this study, the distribution characteristics of nutrients, HM, and microbial community in the sediments along the Longsha River, a tributary of the Pearl River (or Zhu Jiang), China were investigated by analyzing samples from 11 sites. On the basis of the HM-contamination level, the 11 sampling sites were divided into three groups to explore the changes in microbial communities at different ecological risk levels. Results indicated that nutrient concentrations were higher near farmlands and residential lands, while the ecological risk of HM at the 11 sampling sites was from high to low as S10 > S2 > S9 > S6 > S11 > S7 > S5 > S8 > S3 > S4 > S1. Among these HM, Cu, Cr, and Ni had intense ecological risks. In addition, the results of Variance Partitioning Analysis (VPA) revealed a higher contribution of HM (35.93%) to microbial community variation than nutrients (12.08%) and pH (4.08%). Furthermore, the HM-tolerant microbial taxa (Clostridium_sensu_stricto_1, Romboutsia, norank_o__Gaiellales, and etc.) were the dominant genera, and they were more dynamic around industrial lands, while microbes involved in the C, N, and S cycles (e.g., Smithella, Thiobacillus, Dechloromonas, Bacter oidetes_vadinHA17, and Syntrophorhabdus) were inhibited by HM, while their abundance was lower near industrial lands and highway but higher around residential lands. A three-unit monitoring program of land-use types, pollutants, and microbial communities was proposed. These results provide a new perspective on the control of riparian land-use types based on contaminants and microbes, and different microbial community response patterns may provide a reference for contaminant control in sediments with intensive industrial activities.

Uptake of arsenic(V) using iron and magnesium functionalized highly ordered mesoporous MCM-41 (Fe/Mg-MCM-41) as an effective adsorbent

Mesoporous silica (MCM-41) is widely used as a supporting material due to its large specific surface area and good stability, but it cannot remove heavy metals due to the lack of adsorption active sites. In this study, the MCM-41 (a mesoporous SiO₂ material) decorated with iron and magnesium oxide (Fe/Mg-MCM-41) was found to be an excellent adsorbent to remove arsenic(V) from water. FTIR, BET, TEM-EDS, XRD, XPS, etc. were applied for characterization analysis. Adsorption isotherms were fitted well by the Langmuir model and the experimental maximum adsorption capacity of Fe/Mg₄-MCM-41 (magnesium accounts for 4%) was 71.53 mg/g at pH = 3. Thermodynamics analysis suggested exothermic nature of adsorption behavior. Kinetic process was well described by the pseudo-second-order model and adsorption rate was controlled by intraparticle diffusion and film diffusion. Moreover, the adsorption behavior of As(V) onto Fe/Mg₄-MCM-41 was investigated under different reaction conditions, such as pH, temperature, Mg-doping and competing ions. The results showed that loading a certain amount of magnesium can significantly improve arsenic removal efficiency. Additionally, Fe/Mg₄-MCM-41 exhibits high arsenic(V) removal in the wide pH range of 3-10. The Fe/Mg₄-MCM-41 can be regenerated and used after four consecutive cycles. The high arsenic(V) sorption capacity, wide range of pH applications, ability to regenerate, and reusability of Fe/Mg₄-MCM-41 confirmed that this adsorbent is promising for treating As-contaminated wastewater.

Insight into the role and mechanism of polysaccharide in polymorphous magnesium oxide nanoparticle synthesis for arsenate removal

The low cost and non-toxic of magnesium oxides make it a potential eco-friendly material for arsenic removal. Polysaccharide is a kind of green modifier to obtain nanoscale MgO particles with a higher adsorption affinity. In this study, the impact of chain structures of polysaccharides on the morphology features and arsenate removal efficiency of MgO-NPs were investigated. Pullulan and starch facilitated the synthesis of flower-like MgO-NPs, and pectin facilitated the synthesis of plate-like ones. Although the two kinds of flower-like MgO-NPs undergone similar time to reach equilibrium, the one obtained from the starch-synthesis route showed a higher arsenate adsorption capacity (98 mg g^-1), due to that their bushy and smaller petals on the surface provide more active sites for arsenic adsorption. The pectin-synthesis route also produced MgO-NPs with higher arsenate adsorption capacity (101 mg g^-1), ascribed to stacking of nano-plates on their surfaces facilitated to form defect surfaces. However, due to their lower BET area, the plate-like MgO-NPs took twice times to reach equilibrium for arsenic adsorption compared with the others. In the stage for the hydrolysis of MgO, hydroxyl groups on the polymer chain provide active sites to physically trap or bond with MgO particles and then to produce hydrolyzed precursors. The poly chain containing inter- and intra-hydroxyl groups directed MgO molecular growing into hydroxide crystals with 3D frameworks during their nucleation and growth. However, pectin only provides inter-hydroxyl groups and directs to form hydroxides with 2D frameworks. Furthermore, the rapid-nucleation vs. slow-growth model in the stage of pyrolysis of hydroxide crystals successfully interprets the thinner petals and complex chemical phases of the final nanoparticles obtained from the pullulan-synthesis route. This work may provide direction and perspectives for the rational design of well-performing MgO materials for arsenate removal.

Multilayered TNAs/SnO2/PPy/β-PbO2 anode achieving boosted electrocatalytic oxidation of As(III)

Dealing with arsenic pollution has been of great concern owing to inherent toxicity of As(III) to environments and human health. Herein, a novel multilayered SnO₂/PPy/β-PbO₂ structure on TiO₂ nanotube arrays (TNAs/SnO₂/PPy/β-PbO₂) was synthesized by a multi-step electrodeposition process as an efficient electrocatalyst for As(III) oxidation in aqueous solution. Such TNAs/SnO₂/PPy/β-PbO₂ electrode exhibited a higher charge transfer, tolerable stability, and high oxygen evolution potential (OEP). The intriguing structure with a SnO₂, PPy, and β-PbO₂ active layers provided a larger electrochemical active area for electrocatalytic As(III) oxidation. The as-synthesized TNAs/SnO₂/PPy/β-PbO₂ anode achieved drastically enhanced As(Ⅲ) conversion efficiency of 90.72% compared to that of TNAs/β-PbO₂ at circa 45.4%. The active species involved in the electrocatalytic oxidation process included superoxide radical (•O₂^-), sulfuric acid root radicals (•SO₄^-), and hydroxyl radicals (•OH). This work offers a new strategy to construct a high-efficiency electrode to meet the requirements of favorable electrocatalytic oxidation properties, good stability, and high electrocatalytic activity for As(III) transformation to As(V).

Strategy of optimizing anaerobic digestion of cassava distiller wastewater using a novel automatic biological incubation system

Due to the drawbacks of using fossil fuels and the need to mitigate global warming caused by increasing greenhouse gas emissions, agricultural biomass for bioenergy production is gaining great interest around the world. This work presented a study at a biochemical plant in Lianyungang, Jiangsu Province, China to maximize methane production from cassava distiller wastewater. The plant's annual production of cassava distiller wastewater is more than 3 million tons and currently was treated using a series of 5000 m³ Internal Circulation (IC) reactors. Modification was applied at No.19 IC reactor by connecting it to two 1 m³ automatic biological incubators called Information Bio-Booster (IBB). The effluent of the IC reactor was fed into the IBBs and iron, cobalt and nickel were added directly in the IBBs. The function of the IBBs was to regulate the microbial community. Afterwards, the microorganisms in the IBBs were pumped back into the IC reactor to participate in the methane production reaction. Daily net increase of methane content and COD removal reached 8.02% and 33% respectively in No.19 IC reactor comparing to the unadjusted reactors. Preliminary lab experiments found that improvements of biogas production, enhanced COD removal and VS removal was closely related to the enhancement of anaerobic microbial communities' diversity and the promotion of enzyme activity through the addition of the metal salts. Daily economic value could be estimated to be $218 which indicated the application potential of using the proposed system to enhance anaerobic digestion at industrial plants for bioenergy production.

Dark fermentation: Production and utilization of volatile fatty acid from different wastes- A review

Volatile fatty acids (VFAs) are the building blocks of the chemical industry, and they are the primary contributors to the planet's organic carbon cycle. VFA production from fossil fuels (mostly petroleum) is unsustainable, pollutes the environment, and generates greenhouse gases. As a result of these issues, there is a pressing need to develop alternate sources for the long-term generation of VFAs via anaerobic digestion. The accessible feedstocks for its sustainable production, as well as the influencing parameters, are discussed in this review. The use of VFAs as a raw material to make a variety of consumer products is reviewed in order to find a solution. It also bridges the gap between traditional and advanced VFA production and utilization methods from a variety of solid and liquid waste sources for economical stability.

Single-Step Hydrothermal Synthesis of Biochar from H3PO4-Activated Lettuce Waste for Efficient Adsorption of Cd(II) in Aqueous Solution

Developing an ideal and cheap adsorbent for adsorbing heavy metals from aqueous solution has been urgently need. In this study, a novel, effective and low-cost method was developed to prepare the biochar from lettuce waste with H3PO4 as an acidic activation agent at a low-temperature (circa 200 °C) hydrothermal carbonization process. A batch adsorption experiment demonstrated that the biochar reaches the adsorption equilibrium within 30 min, and the optimal adsorption capacity of Cd(II) is 195.8 mg∙g-1 at solution pH 6.0, which is significantly improved from circa 20.5 mg∙g-1 of the original biochar without activator. The fitting results of the prepared biochar adsorption data conform to the pseudo-second-order kinetic model (PSO) and the Sips isotherm model, and the Cd(II) adsorption is a spontaneous and exothermic process. The hypothetical adsorption mechanism is mainly composed of ion exchange, electrostatic attraction, and surface complexation. This work offers a novel and low-temperature strategy to produce cheap and promising carbon-based adsorbents from organic vegetation wastes for removing heavy metals in aquatic environment efficiently.

Bioremediation of trichloroethylene-polluted groundwater using emulsified castor oil for slow carbon release and acidification control

In this study, the emulsified castor oil (ECO) substrate was developed for a long-term supplement of biodegradable carbon with pH buffering capacity to anaerobically bioremediate trichloroethylene (TCE)-polluted groundwater. The ECO was produced by mixing castor oil, surfactants (sapindales and soya lecithin [SL]), vitamin complex, and a citrate/sodium phosphate dibasic buffer system together for slow carbon release. Results of the emulsification experiments and microcosm tests indicate that ECO emulsion had uniform small droplets (diameter = 539 nm) with stable oil-in-water characteristics. ECO had a long-lasting, dispersive, negative zeta potential (-13 mv), and biodegradable properties (viscosity = 357 cp). Approximately 97% of TCE could be removed with ECO supplement after a 95-day operational period without the accumulation of TCE dechlorination byproducts (dichloroethylene and vinyl chloride). The buffer system could neutralize acidified groundwater, and citrate could be served as a primary substrate. ECO addition caused an abrupt TCE adsorption at the initial stage and the subsequent removal of adsorbed TCE. Results from the next generation sequences and real-time polymerase chain reaction (PCR) indicate that the increased microbial communities and TCE-degrading bacterial consortia were observed after ECO addition. ECO could be used as a pH-control and carbon substrate to enhance anaerobic TCE biodegradation effectively. PRACTITIONER POINTS: Emulsified castor oil (ECO) contains castor oil, surfactants, and buffer for a slow carbon release and pH control. ECO can be a long-term carbon source for trichloroethylene (TCE) dechlorination without causing acidification. TCE removal after ECO addition is due to adsorption and reductive dechlorination mechanisms.

Highly efficient removal of Cr(VI) from aqueous solution by pinecone biochar supported nanoscale zero-valent iron coupling with Shewanella oneidensis MR-1

Nanoscale zero-valent iron (nZVI) has been extensively used to remove various pollutants. However, the rapid deactivation due to aggregation and surface passivation severely limits its practical application. In this study, a novel composite with nZVI supported by pinecone biochar (nZVI-PBC) was successfully synthesized and used for the removal of high concentration Cr(VI) from aqueous solution in the presence of Shewanella oneidensis MR-1 (MR-1). The results showed that the nZVI-PBC coupling with MR-1 (nZVI-PBC/MR-1) exhibited an excellent removal performance for high concentration Cr(VI) compared to the nZVI-PBC alone. Under optimal conditions, 100 mg/L Cr(VI) could be removed completely by nZVI-PBC/MR-1 within 48 h, while only 39.50% of Cr(VI) was removed by nZVI-PBC alone. The improvement of Cr(VI) removal is due to the dissolution of the surface passivation layer of nZVI-PBC, formation of sorbed Fe(II) in the presence of MR-1, and an important role of extracellular polymeric substance (EPS) derived from MR-1. X-ray photoelectron spectroscopy (XPS) and Cr K-edge X-ray absorption near-edge structure spectra (XANES) confirmed that most Cr(VI) was reduced to insoluble Cr(III) and formed Cr₂O₃, Cr_xFe_1-x(OH)₃ and FeCr₂O₄ precipitates, and a small amount of unreduced Cr(VI) was immobilized through adsorption and complexation. The results suggest that nZVI-PBC/MR-1 can effectively overcome the limitations of nZVI and achieve highly efficient removal of high concentration Cr(VI).

Combining electrochemical nitrate reduction and anammox for treatment of nitrate-rich wastewater: A short review

Treatment of nitrate-rich wastewater is important but challenging for the conventional biological denitrification process. Here, we propose combining the electrochemical reduction and anaerobic ammonium oxidation (anammox) processes together for treatment of nitrate-rich wastewater. This article reviews the mechanism and current research status of electrochemical reduction of nitrate to ammonium as well as the mechanism and applicability of the anammox process. This article discusses the principles, superiorities and challenges of this combined process. The feasibility of the combined process depends on the efficiency of electrochemical nitrate reduction to ammonium and the conditions in the anammox process to use the reduced ammonium as the substrate to achieve deep nitrogen removal. The article provides a feasible strategy for using the electrochemical reduction and anammox combined process to treat nitrate-rich wastewater.

Greenhouse gas emissions in sludge ultrasonication followed by anaerobic digestion processes

This paper presents the greenhouse gas (GHG) emissions during ultrasonication of sludge and anaerobic digestion (AD) of the ultrasonicated sludge using mass-energy balance. Computation of the net energy (energy recovered - energy input) revealed that high solids concentration with low sonication specific energy provides positive net energy. Moreover, the GHG emissions can be minimised at low sonication specific energy input and high solids concentration compared to that of the control without sonication. Increase in temperature of sludge during sonication will reduce the energy input required for raising the sludge temperature to AD temperature and thus decreases the GHG emissions. With energy recovery from the methane produced in AD, the total GHG emissions can further be reduced, lower than that without energy recovery from methane.

Bioelectrochemical systems with a cathode of stainless-steel electrode for treatment of refractory wastewater: Influence of electrode material on system performance and microbial community

The large-scale application of the bioelectrochemical system (BES) is limited by the cost-effective electrode materials. In this study, five kinds of stainless-steel materials were used as the cathode of the BES coupled with anaerobic digestion (BES-AD) for the treatment of diluted N, N-dimethylacetamide (DMAC) wastewater. Compared with a carbon-cloth cathode, BES-AD with a stainless-steel cathode had more engineering due to its low cost, although the operating efficiencies were slightly inferior. Stainless-steel mesh with a 100 µm aperture (SSM-100 μm) was the most cost-effective electrode and the implanted BES exhibited better COD removal efficiency, electrochemical performance and biodegradability. Analysis of microbial community revealed the synergetic effect between exoelectrogen and fermentative bacteria had been strengthened in the SSM-100 μm cathode biofilm. Function analysis of the microbial community based on PICRUSt predicted metagenomes revealed that the metabolic pathways of xenobiotics biodegradation and metabolism in the SSM-100 μm cathode were stimulated.