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Anaerobic fermentation (AF) could achieve simultaneous recovery of short-chain fatty acids (SCFAs) and phosphorus (P) when waste activated sludge (WAS) and meat processing waste (MPW) act as co-substrate. However, long-chain fatty acids, the degradation intermediates of lipids, always inhibit anaerobic microbial activity. Therefore, sodium hydroxide (NaOH) conditioning was applied to improve the lipid-rich AF performance in this study. The results demonstrated that 96% WAS (v/v) with NaOH addition that remaining at pH 7.5 could achieve the maximum SCFAs yield (1180.05 mg/g VS fed) at 12 d, and ortho-P content in the AF liquor (AFL) was much more than that of without NaOH addition. Anaerovibrio and Aminobacterium , one kind of lipolytic and proteolytic bacteria, respectively, became the major genus in the lipid-rich AF system. 86% of P in the AFL from 96% WAS + pH 7.5 reactor was recovered through vivianite crystallization method, with 91% of SCFAs remaining in the post-AFL. Meanwhile, analysis results verified vivianite formation in the P precipitate products. Overall, this study provided a new idea to achieve SCFAs and P simultaneous recovery from WAS and MPW through AF with NaOH conditioning and vivianite crystallization. [Display omitted] • Meat processing waste and activated sludge were treated by anaerobic fermentation. • NaOH conditioning enhanced SCFAs yield and P release from lipid-rich AF. • Maximal SCFAs yield (1180.05 mg/g VS fed) occurred at pH 7.5 with NaOH addition. • Anaerovibrio , one kind of lipolytic bacteria, was stimulated during lipid-rich AF. • Ortho-P release from the fermentation system was favorable for vivianite recovery. [ABSTRACT FROM AUTHOR]

This paper provides a comprehensive overview of the current state of development of transition metal macrocyclic (TMM) complex-based electrocatalysts used in oxygen reduction reactions (ORRs) in polymer electrolyte membrane fuel cells (PEMFCs). Up to date performances of carbon material-supported TMM catalysts, including both ORR activity rates and stabilities are, discussed. The effects of different types and natures of metals, macrocyclic ligands, ligand substitutions, catalyst supporting materials, electrode preparation, and various acid/alkaline solutions are thoroughly analyzed and reviewed based on the published literature. The ORR mechanisms facilitated by these TMM catalysts are discussed from both a theoretical and experimental observation point of view. Required improvements in ORR activity, stability and commercial viability in order for TMM complex-based electrocatalysts to be utilized in PEMFCs are identified. Potential research directions to overcome current challenges are also suggested to facilitate future efforts in this area. [ABSTRACT FROM AUTHOR]

Anaerobic-oxic membrane bioreactor (AOMBR) has been proposed as a highly effective method in municipal and industrial wastewater treatment. In this study, according to the sewage treatment system in a campus, long-term experiments were conducted to assess the impacts of the sludge retention time (SRT) on sludge characteristics and membrane fouling, and the sludge parameters include biomass concentration, particle size distribution, extracellular polymeric substances (EPS), soluble microbial products (SMPs), and specific resistance to filtration (SRF). Our results clearly demonstrated that SRT was one of the most important factors influencing sludge characteristics, and different sludge characteristics resulted in different membrane fouling degrees. A better treatment and filtration performances were observed at the SRT of 30 days compared to two SRTs of 10 and 90 days. Among these parameters, SMP had the most significant correlation with the membrane fouling rate (dTMP/d t), and it had a negative impact on membrane filtration performance. The impact of SRT on membrane fouling process was discussed further by filtration models. At 10 days SRT, the complete-standard blocking model curve had a comparatively higher goodness-of-fit with the fouling process, and at 30 and 90 days SRT, the cake-standard blocking model curve had a relatively higher goodness-of-fit with respective fouling process. [ABSTRACT FROM AUTHOR]

Quinoline is a critical raw material for the dye, metallurgy, pharmaceutical, rubber, and agrochemical industries, and its use poses a serious threat to human health and the ecological environment. Quinoline has carcinogenic, teratogenic and mutagenic effects on the human body through food accumulation. However, due to the steric hindrance of its bicyclic fused structure and its long photooxidation half-life, quinoline is too difficult to decompose naturally. To date, numerous technologies have been used to degrade quinoline, whereas only a few have been reviewed. Therefore, this paper is focused on offering a comprehensive overview of the state of quinoline degradation in an effort to improve its degradation efficiency and fully utilize the carbon and nitrogen within quinoline without causing any damage to the environment. Accordingly, the strains, research progress and mechanisms of various methods for degrading quinoline are explored and elucidated in detail, especially quinoline biodegradation and the combination of these technologies for efficient removal. The state-of-the-art processes and new findings of our team on the biofortification of quinoline degradation are also presented. Finally, research bottlenecks and gaps for future research were identified along with the prospects and resource utilization of quinoline. These discussions facilitate the realization of the zero discharge of quinoline. Unlabelled Image • Research progress and various mechanisms of quinoline biodegradation were elucidated. • Research bottlenecks and gaps for future research were also identified. • State of art processes for biofortification of quinoline degradation are presented. • Efficient open loop methods also need to be further explored. • Future research may focus on the use of C and N in quinoline instead of being removed. [ABSTRACT FROM AUTHOR]

Photocatalytic hydrogen evolution via water splitting was considered as a promising way of solar energy conversion and storage in the past decades. However, the weak visible-light response and fast recombination of electron-hole pairs are still main obstacles to overcome. Herein, a novel 2D/2D Bi 4 O 5 Br 2 /TL-Ti 3 C 2 (Thin layer-Ti 3 C 2) visible-light photocatalyst was successfully prepared by in-situ synthesis of Bi 4 O 5 Br 2 nanosheets on the surface of TL-Ti 3 C 2 at room temperature. The resulting Bi 4 O 5 Br 2 /TL-Ti 3 C 2 exhibits a higher hydrogen evolution activity (83.5 ​μmol·g−1·h−1) than that of pristine Bi 4 O 5 Br 2 (44.9 ​μmol·g−1·h−1) under visible-light irradiation. The enhanced hydrogen evolution activity of as-prepared photocatalyst mainly attributes to the increased visible light responsiveness and rapid transfer of photo-induced electrons. The strong interaction between TL-Ti 3 C 2 and Bi3+ in Bi 4 O 5 Br 2 nanosheets establishes a good electron transfer channel and close contact, which accelerates the transfer of photo-induced electrons from Bi 4 O 5 Br 2 to Ti 3 C 2 and promotes the separation of photo-generated charge carriers, thereby increasing the number of effective photo-induced electrons involved in the hydrogen evolution. This work provides a new insight into the construction of Bi x O y Br z /MXene photocatalyst system, and demonstrated that Ti 3 C 2 has excellent application potential in promoting the photocatalytic performance of bismuth-rich bismuth oxyhalides (Bi x O y X z X ​= ​Cl, Br, I). Benefiting from the rapidly transfers photo-induced electrons and increases the visible light responsiveness, the resulting 2D Bi 4 O 5 Br 2 /2D TL-Ti 3 C 2 manifests more significant photocatalytic hydrogen evolution activity (83.5 ​μmol·g−1·h−1) than that of pristine Bi 4 O 5 Br 2 (44.9 ​μmol·g−1·h−1). This work provides a new insight into the construction of Bi x O y Br z /MXene photocatalyst system, and demonstrated that Ti 3 C 2 has excellent application potential in promoting the photocatalytic performance of bismuth-rich bismuth oxyhalides (Bi x O y X z X ​= ​Cl, Br, I). Image 1 • Bi 4 O 5 Br 2 /Thin layer-Ti 3 C 2 was prepared by in-situ synthesis at room temperature. • Bi 4 O 5 Br 2 /Thin layer-Ti 3 C 2 manifests better photocatalytic H 2 evolution than Bi 4 O 5 Br 2. • The enhanced activity was mainly attributed to the rapidly charge transfer. • An electron transfer channel was established in Bi 4 O 5 Br 2 /Thin layer-Ti 3 C 2. • The possible H 2 evolution mechanism of Bi 4 O 5 Br 2 /Thin layer-Ti 3 C 2 was proposed. [ABSTRACT FROM AUTHOR]

Bioretention has been widely used in urban non-point source (NPS) pollution management for effectively reducing downstream pollution loads and peak flows. However, nitrogen (N) removal in conventional bioretention systems has been uniformly unstable and highly variable due to a lack of anaerobic denitrification. To improve the stability and effectiveness of N removal, two bioretention columns with bilayer media (C1 and C2) were designed. High permeability quartz sand (~2 mm diameter) was used as the upper media, and low permeability modified media (~0.6 mm diameter, adding 5% organic substance) as the lower media. The bilayer media structure formed an anaerobic zone for promoting denitrification processes. The results showed that the retrofitted columns performed well and that the removal efficiencies of various forms of N were considerably enhanced to 76.8%–95.3%, 85.1%–98.3%, and 87.5%–97.4% for TN, NH 4 +-N, and NO 3 −-N, respectively. Additionally, copying numbers of the denitrification functional genes detected via FQ-PCR in the lower media of C1 and C2 were accounted for 46.06% and 44.16% of the 16S rDNA gene, respectively. These results confirmed the presence of anaerobic denitrification processes. Consequently, bilayer media bioretention systems are worth promoting in cities where nitrogen in urban runoff poses a threat to the receiving surface water, due to the systems' remarkable performance in nitrogen removal, simple structure, and easy implementation. Unlabelled Image • Bilayer media bioretention was designed and constructed to improve N removal. • The bilayer media structure increased adsorption capacity, hydraulic retention time. • Ammonia nitrogen was mainly captured by adsorption in the upper layer. • Nitrate nitrogen was largely converted by denitrification in the lower media layer. • The lower media had a high proportion of denitrification genes detected via FQ-PCR. [ABSTRACT FROM AUTHOR]

• A novel 2D/3D Bi 5 O 7 Br/BiOBr was prepared via one-step hydrolysis method. • The Bi 5 O 7 Br/BiOBr exhibited better visible light degrade pharmaceutical activity. • The Bi 5 O 7 Br/BiOBr showed tight contact and superior electron-hole separation rate. • The photocatalytic mechanism of Bi 5 O 7 Br/BiOBr was proposed. BiOBr-based composite photocatalysts had attracted extensive attention for efficient photocatalytic degradation aqueous organic pollutants in the past decade. However, the catalysis ability of photocatalyst is greatly limited by their intrinsic high recombination rate of photo-generated charge carriers. Herein, we solve this problem by constructing a novel 2D/3D Bi 5 O 7 Br/BiOBr heterojunction photocatalyst that was prepared via one-step facile hydrolysis process. The pure Bi 5 O 7 Br and pure BiOBr photocatalysts were also obtained by only adjusting the pH value of the mixed solution. The obtained products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), optical and electric property analysis and etc. The results suggested that 2D Bi 5 O 7 Br nanosheets tightly attached to the surface of BiOBr 3D structure with nanoflakes self-assembled microsphere, which could increase the transfer and separation efficiency of photogenerated charges. Furthermore, the 2D/3D Bi 5 O 7 Br/BiOBr heterojunction exhibited superior visible light photocatalytic performance for carbamazepine (CBZ) degradation than pure BiOBr and pure Bi 5 O 7 Br, which owing to the enhanced separation of photoinduced electrons and holes. At last, the underlying photocatalytic mechanism is elucidated based on the band structure and radical scavenging experiments. This work provided a feasible design idea to one-step construct 2D/3D nanocomposite for pharmaceutical wastewater purification. [ABSTRACT FROM AUTHOR]

[Display omitted] • An idea and method of screening high selectivity and high activity electrocatalysts by machine learning was proposed. • The potential relationship between the physical properties of single-atom catalysts and their adsorption and catalytic properties was found. • Zn@ Pc -N 3 C 1 , Au@Pd-N 4 , Au@Pd-N 1 C 3 and Au@Py-N 3 C 1 were identified as electrocatalysts with high selectivity and activity for 2e- oxygen reduction reaction to prepare H 2 O 2. • The unique advantages of single-atom catalysts as the electrocatalyst for 2e- oxygen reduction reaction to prepare H 2 O 2 were explained and proved. Electrocatalysis has emerged as one of the most promising alternatives to conventional anthraquinone for preparing hydrogen peroxide (H 2 O 2) with high energy consumption and pollution because of its simplicity, convenience, and environmental friendliness. However, the oxygen reduction reaction (ORR) generating H 2 O 2 via the 2e- path is a competitive path for 4e–ORR to generate H 2 O. Therefore, it is crucial to identify an electrocatalyst with high selectivity and activity of 2e-ORR. Here, we established five machine learning (ML) models based on the adsorption free energy of O* (△G (O*)) of 149 single-atom catalysts (SACs) collected and the limiting potential (U L) of 31 SACs calculated using density functional theory (DFT) from the literature. We then obtained descriptors that could accurately describe SACs. Furthermore, 690 unknown SACs' 2e-ORR catalytic performance was well predicted. Four 2e-ORR materials with high selectivity and activity were screened: Zn@ Pc -N 3 C 1 , Au@Pd-N 4 , Au@Pd-N 1 C 3 , and Au@Py-N 3 C 1. We verified the U L of these SACs through DFT calculation, which was higher than the standard value, proving the ML model's validity. The ML-based method to predict the material properties with highly selective and active electrocatalysts provides an efficient, rapid, and low-cost method for discovering and designing more valuable SACs catalysts. [ABSTRACT FROM AUTHOR]

• Bio-foaming seemed to be caused by the accumulation of volatile fatty acids. • CH 4 yield was increased by 2.5–11.3% after Fe0 dosing at a loading rate of 7.5 kgVS/m3/d. • Addition of Fe0 decreased the degree of effluent surface active by 49.7–59.2%. • Fe0 dosing was assessed by comparison with commercial antifoam agents. Bio-foaming during the anaerobic digestion (AD) of the organic fraction of municipal solid waste (OFMSW) is a major cause of unstable reactor operations, especially under high organic loading rates (OLRs). Here, we used two 40-liter anaerobic reactors to deal with the actual organic fraction of municipal solid waste at OLRs of 5 and 7.5 kgVS/m3/d and tried to inhibit bio-foam generation by dosing with Fe0. One of reactors had 400 g of Fe0 added before operation and additional 200 g of Fe0 was added when the operating conditions changed; the other one was the control reactor with no Fe0 dosing. The results show that bio-foam was generated in the control reactor at an organic shock loading of 10 kgVS/m3/d and re-startup at 5 kgVS/m3/d, while the reactor containing Fe0 operated normally. Due to the surfactant attributes of volatile fatty acids (VFAs), the probability of bio-foam generation was positively correlated with the effluent's degree of surface activity (SA) induced by VFAs, which is a parameter representing the foaming potential. Because VFA biodegradation was enhanced in the reactor with added Fe0, at the position of Fe0 accumulation, the SA was decreased by 49.7–59.2%. Furthermore, the effect of Fe0 dosing on inhibiting bio-foam was evaluated by comparison with traditional commercial anti-foam agents. The results suggest possible reasons for bio-foam generation in OFMSW AD and suggest the reasonable usage of Fe0 to inhibit bio-foam formation. [ABSTRACT FROM AUTHOR]

For quinoline-denitrifying degradation, very few researches focused on shortcut denitrification process and its bacterial community characteristics. In this study, complete and shortcut denitrification systems were constructed simultaneously for quinoline degradation. By calculation, specific quinoline removal rates were 0.905 and 1.123 g/(gVSS d), respectively, in the complete and shortcut systems, and the latter was 1.24 times of the former. Polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE), high-throughput sequencing, and quantitative PCR (qPCR) techniques based on 16S rRNA were jointly applied to compare microbial community structures of two systems. Many denitrifying bacteria phyla, classes, and genera were detected in the two systems. Phylum Proteobacteria, Class Gammaproteobacteria, and Genus Alicycliphilus denitrificans were the dominant contributors for quinoline-denitrifying degradation. In the shortcut denitrification system, main and specific strains playing crucial roles were more; the species richness and the total abundance of functional genes ( narG, nirS, nirK, and nosZ) were higher compared with the complete denitrification system. It could be supposed that inorganic-nitrogen reductase activity of bacterial community was stronger in the shortcut denitrification system, which was the intrinsic reason to result in higher denitrification rate. [ABSTRACT FROM AUTHOR]

Persulfate oxidation (PS) is widely employed as a promising alternative for waste activated sludge pretreatment due to the capability of generating free radicals. The product differences and microbiological mechanisms by which PS activation triggers WAS digestion through multiple modes need to be further investigated. This study comprehensively investigated the effects of persulfate oxidation activated through multiple modes, i.e., ferrous, zero-valent iron (ZVI), ultraviolet (UV) and heat, on the performance of sludge digestion. Results showed that PS_ZVI significantly accelerated the methane production rate to 12.02 mL/g VSS. By contrast, PS_Heat promoted the sludge acidification and gained the maximum short-chain fatty acids (SCFAs) yield (277.11 ± 7.81 mg COD/g VSS), which was 3.41-fold compared to that in PS_ZVI. Moreover, ferrous and ZVI activated PS achieved the oriented conversion of acetate, the proportions of which took 73% and 78%, respectively. MiSeq sequencing results revealed that PS_Heat and PS_UV evidently enriched anaerobic fermentation bacteria (AFB) (i.e., Macellibacteroides and Clostridium XlVa). However, PS_Ferrous and PS_ZVI facilitated the enrichment of Woesearchaeota and methanogens. Furthermore, molecular ecological network and mantel test revealed the intrinsic interactions among the multiple functional microbes and environmental variables. The homo-acetogens and sulfate-reducing bacterial had potential cooperative and symbiotic relationships with AFB, while the nitrate-reducing bacteria displayed distinguishing ecological niches. Suitable activation modes for PS pretreatments resulted in an upregulation of genes expression responsible for digestion. This study established a scientific foundation for the application of sulfate radical-based oxidation on energy or high value-added chemicals recovery from waste residues. [Display omitted] • Effect of multiple activated persulfate oxidation on sludge digestion was studied. • Heat and UV activated persulfate effectively promoted the accumulation of SCFAs. • ZVI and Ferrous activated persulfate were beneficial for methane production. • Microbial community structures were altered by multiple persulfate activation modes. • Suitable activation modes for persulfate upregulated the critical genes expression. [ABSTRACT FROM AUTHOR]

• 150 mgN/L of nitrate photolysis improved SCFAs production from WAS. • Nitrate increase (150∼375 mgN/L) has no significant promotion on SCFAs in photolysis. • ROS contributed more than RNS on WAS solubilization, hydrolysis and acidification. • Both AFB and NRB enriched for the high SCFAs production and complete denitrification. • Genes related to glycolysis, amino acid, acetate and nitrogen metabolism were enhanced. Nitrate photolysis has become an efficient, low-cost and promising technology for emerging contaminants removal, while its performance and mechanism for waste activated sludge (WAS) treatment is still unknown. This study innovatively introduced nitrate photolysis for WAS disintegration, and investigated the effect of nitrate addition (150–375 mg N/L) for short-chain fatty acids (SCFAs) production during anaerobic fermentation (AF). The results showed that nitrate photolysis significantly promoted the SCFAs production from WAS, and peaked at 280.7 mg/g VSS with 7-d fermentation with 150 mg N/L addition (150N-UV), which increased by 8.8–35.0 % and 10.7–23.3 % compared with other photolysis groups and sole nitrate groups. Effective release of the soluble organics was observed in the nitrate photolysis groups during AF, especially soluble proteins, reaching 1505.4 mg COD/L at 9 d in 150N-UV group, promoted by 7.0∼15.7 % than nitrate/nitrate photolysis groups. The model compounds simulation experiment further demonstrated the positive effect of nitrate photolysis on organics hydrolysis and SCFAs accumulation. The result of the radical capture and quenching verified the reactive oxygen species contributed more compared with reactive nitrogen species. Functional group analysis confirmed the effective bioconversion of the macromolecular organics during the fermentation. Moreover, the nitrate photolysis enhanced the enrichment of the functional consortia, including anaerobic fermentation bacteria (AFB), e.g., Fnoticella, Romboutsia, Gracilibacter and Sedimentibacter , and nitrate reducing bacteria (NRB), e.g., Acinerobacter and Ahniella. The macrogenetic analysis further revealed that glycolysis, amino acid metabolism, acetate metabolism and nitrogen metabolism were the dominating metabolic pathways during fermentation, and the abundance of the relevant genes were enhanced in 150N-UV group. [Display omitted] [ABSTRACT FROM AUTHOR]

Electro-fermentation (EF) has been extensively studied for recovering hydrogen and phosphorus from waste activated sludge (WAS), while was limited for the further application due to the low hydrogen yield and phosphorus recovery efficiency. This study proposed an efficient strategy for hydrogen and vivianite recovery from the simulated sludge fermentation liquid by sacrificial iron anode in EF. The optimum hydrogen productivity and the utilization efficiency of short chain fatty acids (SCFAs) reached 45.2 mmol/g COD and 77.6% at 5 d in pH 8. Phosphate removal efficiency achieved at 90.8% at 2 d and the high crystallinity and weight percentage of vivianite (84.8%) was obtained. The functional microbes, i.e., anaerobic fermentative bacteria, electrochemical active bacteria, homo-acetogens and iron-reducing bacteria were highly enriched and the inherent interaction between the microbial consortia and environmental variables was thoroughly explored. This work may provide a theoretical basis for energy/resource recovery from WAS in the further implementation. [Display omitted] • Enhanced hydrogen and vivianite recovery were realized in pH 8 via Fe mediated EF. • Appropriate iron release led to the higher crystallinity of vivianite in pH 8 group. • EAB, AFB and homo-acetogens preferred to enrich in pH 8 than other pH conditions. • The mutual symbiosis of microbes and environmental factors was the main mechanism in EF. [ABSTRACT FROM AUTHOR]

[Display omitted] • Specific colonization pattern of key symbionts in MES was firstly investigated. • Co-colonization of EAB and CSB promoted caproate biosynthesis in MES. • CSB and EAB mutually interacted in metabolic activity and enhanced electron transfer. • Ecological mechanism was revealed in terms of MEN analysis and Mantel test. • Economic benefit and carbon emission were preferable via co-colonization. As promising and value-added platform chemicals, the biosynthesis of medium-chain fatty acids (MCFAs, C6-C12) via chain elongation (CE) in microbial electrosynthesis systems (MES) has recently garnered significant attentions due to the unique bioelectrocatalytic behaviors and the reduction of exogenous electron donors (EDs). Caproate-synthesizing bacteria (CSB) played a crucial role in the generation of acetyl-CoA, which subsequently underwent reverse β oxidation to synthesize MCFAs. However, the presence of electrochemically active bacteria (EAB) was also pivotal for MES as they generated hydrogen in the cathodic electron transfer pathways, the specific colonization patterns of key symbionts remained unknown. The aim of this study was to investigate the selective colonization of EAB and CSB on the performance of caproate production in MES. The reactors colonized EAB and CSB achieved the maximum caproate concentration of 5332.5 mg COD/L, which was 7.9 and 1.3 times higher compared to that inoculated with either sole EAB or CSB, respectively. Moreover, the reactors colonized with mixed culture exhibited a clear redox peak and preferable electron transfer efficiency. CSB and EAB mutually interacted in metabolic activities, thereby resulting in increased substrate utilization and caproate production. The findings of this study provide a new strategy and insights for value-added chemicals recovery in microbial electrosynthesis platform. [ABSTRACT FROM AUTHOR]

[Display omitted] • Pyrolytic carbon from waste tire pyrolysis was used to boost the AD performance. • Pyrolysis temperature for pyrolytic carbon used in AD should be higher than 800 °C. • The conductivity of pyrolytic carbon at 1000 °C is (12.5–25.2) × 104 S/m. • The hydrolysis of vinegar residue is enhanced and the VFA content is 3330 mg/L. • The maximal CH 4 yield is 454.53 mL CH 4 /gVS, representing an increase of 104.4%. Random disposal of waste tires and vinegar residues is deleterious to the environment; these materials can be sufficiently treated using pyrolysis and anaerobic digestion, respectively. In this study, pyrolytic carbon was used to enhance the performance of the anaerobic digestion of vinegar residues, which is a much more economic method comparing with dosing commercial-level carbon based materials. The conductivity of pyrolytic carbon at 1000 °C is much higher than that of commercial activated carbon. At a dosage of 10 g per 29 g of vinegar residues, the maximum volatile fatty acid production was 4225.4 mg COD/L in the reactor (effective volume of 400 mL) with inoculum to substrate ratio (ISR) of 1:1, representing an increase of 50.3% from that of the control reactor. A sufficient dosage is necessary to improve methane yield. The maximum methane yield was obtained at a pyrolytic carbon dosage, obtained at 1000 °C, of 12 g per 29 g of vinegar residues. The results indicated that the differences in the microbial communities of the control and experimental reactors correlated with the performance; however, the deep microbial mechanism of pyrolytic carbon boosting anaerobic digestion performance must be explored in further studies. [ABSTRACT FROM AUTHOR]

Due to the shortage of the 3He gas and its rapidly increasing price, scintillator detectors, the advantages of which are high spatial resolution and capability of detection in real time, become widely used in many neutron instruments. In this work, a position-sensitive neutron detector consisting of a 6LiF/ZnS scintillation screen and a silicon photomultiplier array linked to a capacitive network to detect the positions of incident neutrons, is constructed and tested. To evaluate the detector performance, a series of neutron beam experiments with the detector prototype were performed in the BL20 at the China Spallation Neutron Source. The spatial resolution was measured, and the energy-selective neutron imaging and Bragg edge measurements of a 316L stainless steel sample were performed. A sub-millimeter spatial resolution could be obtained for the detector prototype under study. The detector with such a high spatial resolution is promising for applications in neutron scattering experimental installations, especially for neutron single-crystal diffractometers. [ABSTRACT FROM AUTHOR]

Exploration of value-added products from wastewater treatment plants (WWTPs) was promising for its sustainable development. This study simultaneously addressed the possibility of volatile fatty acids (VFAs) production boost and cellulosic components recovery from fine-sieving fractions (FSF) under initial alkaline conditions. The step utilization of FSF was relatively untapped in similar literatures. The effect of different initial pH values with 8.5, 9.5 and 10.5 (defined as F-8.5, F-9.5 and F-10.5) on fermentation performance were investigated. Then, the fermentation residues were collected to evaluate the changes in chemical structure and thermodynamic properties by fourier transform infrared spectroscopy (FTIR) and thermo-gravimetric (TG) analysis. Furthermore, analysis of the changes in microbial community structure and the interaction between functional genus and performance parameters were undertaken by high throughput sequencing and canonical correspondence analysis (CCA). Results showed that F-10.5 obtained the highest VFAs yields of 234 mg/g VSS, due to efficient polysaccharides release and inhibited methane production. However, high alkaline intensity caused proteins denaturation. Acidogenesis kinetics suggested that the fermentation rate was chemical-dominated. Although crystalline structure was more disordered with increasing alkalinity, the weight loss was lower than 2.5%, making it possible to recover cellulose from fermented residues. Interaction between functional genus and performance parameters revealed the microbial mechanism during the alkaline fermentation. Consequently, the initial-alkaline motivated fermentation was proved to be a promising technology in value-added products recovery to be cost economic, energy positive and environmental friendly. [Display omitted] • VFAs production was accelerated due to efficient chemical-dominated hydrolysis. • Change in cellulose structure was detected with less weight loss after fermentation. • Alkaline fermentation significantly affected the microbial community structure. • The process was evaluated to be cost effective, energy and environmental positive. [ABSTRACT FROM AUTHOR]

[Display omitted] • The approach resulted in enhanced nitrate removal efficiency of 67 % for the actual wastewater. • The approach resulted in the continuous release of Fe2+ and Fe3+ ions from the Fe0. • The approach increased in (Nitrospira , Hydrogenophaga , Hyphomicrobium , Sphingobium , Thermus , and Meiothermus). • The approach increased enzymes associated with nitrate metabolism (narB, narG, narH, narI, nirA, nasB, and nasC). This study aimed to investigate the effectiveness of combining zero-valent iron (Fe0) with an electric-magnetic field (EMF) with an intensity of 48-mT generated by an alternating current (AC) of 6 V and 50 Hz applied deep within a reactor using actual wastewater obtained from a secondary stage of a wastewater treatment plant (WWTP). The lab-scale experiment was conducted using the UMSR reactor, maintaining a controlled temperature of 25 ± 2 °C and a hydraulic retention time (HRT) of 5-hour, with a dissolved oxygen (DO) level below 1.5 mg/L. Fine Fe0 particles with a size of ≤ 0.3 µm were added into the reactor at a concentration of 3 g/L. The actual wastewater had an approximate nitrate nitrogen (NO 3 –-N) concentration of 30 ± 2 mg/L, and the substrate mass ratio of carbon to nitrogen (C:N) was at 1:1. The results examined the performance of the EMF-Fe0 system in terms of nitrate removal efficiency and the enrichment of denitrifying bacteria, achieving a nitrate removal rate of 67 % with an effluent NO 3 –-N concentration of 10 mg/L and a chemical oxygen demand (COD) concentration of 11.8 mg/L at removal rate of 60 %. Illumina sequencing revealed various enriched denitrifying bacteria after coupling EMF with Fe0, including autotrophic Nitrospira (NOB) at 4 %, denitrification bacteria like Hydrogenophaga at 1.3 %, Hyphomicrobium at 1 %, and Sphingobium at 5 %, along with thermophilic bacteria Thermus at 1.1 % and Meiothermus at 3.5 %. PICRUSt predicted bacterial functions and analyzed interactions, while KEGG and GO analyses linked nitrogen removal pathways to specific species, genes, and enzymes in the EMF-Fe0 system. [ABSTRACT FROM AUTHOR]

High value-added utilization of industrial waste is important for environmental protection and sustainability. The objective of this study was to recycle industrial wastes, silica fume (SF) and aluminium ash (AA) as raw materials to substitute chemicals for sustainable and low-cost SUZ-4 zeolite (L-SUZ-4) synthesis in one pot. The synthesis parameters to obtain pure L-SUZ-4 were optimized as x KOH(x = 7.84–9.33): y Al 2 O 3 (y = 0.81–1.10):2.6TEAOH:21.2SiO 2 : z H 2 O(z = 330.72–712.32) at 150 °C for 96 h. The notably high yield of L-SUZ-4 (up to 85%) indicated that silicon and aluminium species in SF and AA are not only easy to be activated but also liable to be incorporated into the zeolitic framework. Exploration of L-SUZ-4 synthesis process by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) characterizations indicated that the synthesis follows the liquid phase transition mechanism. It can also be observed that the complete dissolution of SF is the rate-determing step during the induction period. Meanwhile, the adsorption ability of L-SUZ-4 for Cd2+ in water was first investigated. A notably maximized adsorption amount (q max = 263.68 mg/g) of L-SUZ-4 for Cd2+ was obtained, which is higher than the other adsorbents investigated in this work or those described in the literature. The sustainable production and outstanding adsorption performance of L-SUZ-4 make it a very promising adsorbent for heavy metal removal with practical application prospects, which is the typical case of "waste to treat waste". [Display omitted] • SUZ-4 zeolite is first prepared using silica fume and aluminum ash by one-pot. • The formation mechanism of the low-cost SUZ-4 zeolite is expatiated. • The low-cost SUZ-4 zeolite displays high adsorption capacity for Cd2+. • The low-cost SUZ-4 is a very promising adsorbent from the practical application. [ABSTRACT FROM AUTHOR]

Environment-friendly nano-catalysts capable of activating peroxymonosulfate (PMS) have received increasing attention recently. Nevertheless, traditional nano-catalysts are generally well dispersed and difficult to be separated from reaction system, so it is particularly important to develop nano-catalysts with both good catalytic activity and excellent recycling efficiency. In this work, magnetically recoverable Fe 3 O 4 -modified ternary CoFeCu-layered double hydroxides (Fe 3 O 4 /CoFeCu-LDHs) was prepared by a simple co-precipitation method and initially applied to activate PMS for the degradation of Rhodamine B (RhB). X-ray diffraction (XRD), fourier transform infrared spectrometer (FT-IR), scanning electron microscope (SEM), transmission electron microscopy (TEM), Brunauer-Emmett-Teller method (BET), and vibrating sample magnetometer (VSM) were applied to characterize morphology, structure, specific surface area and magnetism. In addition, the effects of several key parameters were evaluated. The Fe 3 O 4 /CoFeCu-LDHs exhibited high catalytic activity, and RhB degradation efficiency could reach 100% within 20 min by adding 0.2 g/L of catalyst and 1 mmol/L of PMS into 50 mg/L of RhB solution under a wide pH condition (3.0-7.0). Notably, the Fe 3 O 4 /CoFeCu-LDHs showed good super-paramagnetism and excellent stability, which could be effectively and quickly recovered under magnetic condition, and the degradation efficiency after ten cycles could still maintain 98.95%. Both radicals quenching tests and electron spin resonance (ESR) identified both HO• and SO 4 •− were involved and SO 4 •− played a dominant role on the RhB degradation. Finally, the chemical states of the sample's surface elements were measured by X-ray photoelectron spectroscopy (XPS), and the possible activation mechanism in Fe 3 O 4 /CoFeCu-LDHs/PMS system was proposed according to comprehensive analysis. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel amorphous FeOOH modified light-switchable OVs BiOBr was prepared. • The amorphous FeOOH and light-induced OVs work in tandem to realize the charges directed flow. • The FeOOH/BiOBr exhibited excellent photocatalytic oxygen evolution activity. Directing the transfer of photoinduced charges to various reaction sites through catalyst design plays crucial roles in enhancing photocatalytic oxygen evolution. Herein, we used a facile alcoholysis method to synthesize amorphous FeOOH modified light-switchable oxygen vacancies BiOBr, which exhibited outstanding photocatalytic oxygen evolution activity. Density functional theory calculations, photoelectronchemical tests and kelvin probe force microscopy revealed that FeOOH overlayer acts as the hole storage layer, while oxygen vacancies (OVs) provided a number of electron trap centers. Benefiting from this synergistic effect, the photogenerated charges showed an outstanding directional transfer performance, which greatly prolong the lifetime of the photo-induced charge carriers. Moreover, as a cocatalyst for water oxidation, FeOOH can effectively lower the kinetics barriers and provide more active sites for oxygen evolution reaction. Therefore, under simulated sunlight irradiation, the 2%FeOOH/BiOBr photocatalyst demonstrated remarkable photocatalytic activity towards oxygen evolution, achieving a rate of 284.34 μmol·g−1·h−1, which is around 1.71 folds than pure BiOBr. Finally, the possible reaction mechanism has also been discussed. This work has provided valuable insights and inspiration for the effective design and optimization of BiOBr-based catalysts, which play a critical role in facilitating efficient directional transfer of photogenerated charges. [ABSTRACT FROM AUTHOR]

Inspired by recent advances on functional modification of cellulosic materials, the crosslinking behaviors of epoxide with cellulose under the catalysis of different homogeneous catalysts including H 2 O, Brønsted acid, Brønsted base, Lewis acid and neutral salt were systematically investigated using density functional theory (DFT) methods with hybrid micro-solvation-continuum approach. The results showed that catalytic activity, reaction mechanism and regioselectivity are determined by the combined effect of catalyst type, electronic effect and steric hindrance. All the homogeneous catalysts have catalytic activity for the crosslinking reaction, which decreases in the order of NaOH > HCl > N Cl 3 > M Cl 2 > CH 3 COOH > NaCl (N = Fe3+, Al3+; M = Zn2+, Ca2+). Upon the catalysis of NaOH, hydroxyl group of cellulose is firstly deprotonated to form a carbanion-like intermediate which will further attack the less sterically hindered C atom of epoxide showing excellent regioselectivity. Acidic catalysts readily cause epoxide protonated, which suffers from nucleophilic attack of cellulose and forms the carbocation-like intermediate. Brønsted acid exhibits poor regioselectivity, however, Lewis acid shows an interesting balance between catalytic activity and regioselectivity for the crosslinking reaction, which may be attributed to the unique catalysis and stabilization effects of its coordinated H 2 O on the transition state structure. [Display omitted] • Catalytic activation decreases in the order of NaOH > HCl > N Cl 3 > M Cl 2 > CH 3 COOH > NaCl. • Mechanism, reactivity and regioselectivity depend on catalyst type, electronic effect and steric hindrance. • Lewis acid is suggested in the hydrated form where the coordinated H 2 O has unique catalysis and stabilization effect. • Lewis acid exhibits an interesting balance between catalytic activation and regioselectivity. • The less sterically hindered carbon atom of epoxide prefers to suffer from the nucleophilic attack. [ABSTRACT FROM AUTHOR]

Boosting acetate production from waste activated sludge (WAS) fermentation is often hindered by the inefficient solubilization in the hydrolysis step and the high hydrogen pressure ( p H 2) during the acidogenesis of C3–C5 short-chain fatty acid (SCFAs), i.e., propionate (HPr), butyrate (HBu) and valerate (HVa). Therefore, this study employed persulfate (PS) oxidation and C3–C5 incomplete-oxidative sulfate reducing bacteria (io-SRB) metabolizers to tailor SCFAs conversion from WAS fermentation. The decomposition efficiency, performance of SCFAs production was investigated. Results showed that the PS significantly promoted WAS decomposition, with a dissolution rate of 39.4%, which is 26.0% higher than the un-treated test. Furthermore, SCFAs yields were increased to 462.7 ± 42 mg COD/g VSS in PS-HBu-SRB, which was 7.4 and 2.2 times higher than that of un-treated and sole PS tests, respectively. In particular, the sum of acetate and HPr reached the peak value of 85%, indicating that HBu-SRB mediation promoted the biotransformation of HBu and macromolecular organics by reducing the p H 2 restriction. Meanwhile, sulfate radical (SO 4 ∙-)-based oxidation (SR-AOPs) was effective in the decomposition of WAS, the oxidative product, i.e., sulfate served the necessary electron acceptor for the metabolism of io-SRB. Further analysis of Mantel test revealed the cluster of the functional genus and their interaction with environmental variables. Additionally, molecular ecological network analysis explored the potential synergistic and competitive relationships between critical genera. Additionally, the potential synergistic and competitive relationships between critical genera was explored by molecular ecological network analysis. This study provides new insights into the integration of SR-AOPs with microbial mediation in accelerating SCFAs production from WAS fermentation. [Display omitted] • Integration of SR-AOPs and io-SRB mediation tailored SCFAs conversion from WAS. • SR-AOPs efficiently promoted WAS decomposition with hydrolysis rate increased by 26%. • HBu-SRB promoted C2–C3 SCFAs conversion by reducing the p H 2 restriction. • Synergetic relationship among io-SRB and fermentative genera was revealed. • Thermodynamic mechanism of acetate-oriented conversion by io-SRB was explored. [ABSTRACT FROM AUTHOR]

CdTe and related II–VI compound semiconductors have been widely utilized in the field of optoelectronic devices, detectors, solar cells and so on. As the surface treatment on the wafer involved in the device fabrication process has an important impact on its subsequent photoelectric performance, the investigations on the change in structures and properties of the wafer after different surface treatments, especially the formation of new phases at the surface, have important theoretical significance and practical application value. In this work, the surface morphology and microstructure of CdTe single crystal wafers after different chemical etching processes were investigated by atomic force microscopy (AFM), Raman spectroscopy and transmission electron microscopy (TEM). With the increase of etching time to 10 min, the surface gradually became smoother with a significantly reduced surface roughness from 61.4 nm to 30.5 nm. In addition, the I–V curves of Au/CdTe contact structure illustrate the optimized ohmic contact characteristics after chemical etching with the surface leakage current increasing from 4.723 × 10−10 A to 3.640 × 10−9 A when the etching time extends up to 10 min. TEM analysis on the chemical etched surface of CdTe confirms the formation of Cd2Te2O7 phase with two variants. The d-spacing of (100)CTO and twice that of {111}CdTe being similar is the main reason for the existence of low lattice mismatch and formation of coherent interface between Cd2Te2O7 and CdTe. Furthermore, the chemical etching process is also confirmed to remove the surface damage caused by mechanical polishing effectively by comparing the interface microstructures of Au/CdTe contacts without and after 10 min of chemical etching. The formation mechanism of Cd2Te2O7 and the structure model of Au/CdTe interface are also proposed based on the TEM results. [ABSTRACT FROM AUTHOR]

Maximizing the internal carbon sources in raw wastewater was found to be an alternative option to alleviate the financial burden in external carbon sources (ECS) addition to the biological nutrient removal (BNR) process. Based on previous studies on particulate recovery via fine-sieving technologies, alkali pretreatment was used to improve the short-chain fatty acid (SCFA) production from the fine-sieving fractions (FSF). Hydrolysis performance and methane production were monitored to evaluate the reasons for the SCFA boost. Besides, the microbial community structure was evaluated by high-throughput sequencing. Furthermore, mass balance and financial benefits were preliminarily estimated. The results showed that alkali pretreatment effectively promoted the generation of SCFAs with 234 mg/g volatile suspended solids (VSS), almost double that of the control test. This was partially attributed to the efficient hydrolysis, with soluble polysaccharides and protein increased by 2.1 and 1.2 times compared to that of the control, respectively. Inhibition of methanogens was also devoted to the accumulation of SCFAs, with no methane production until 150 h at high pH value. Finally, a preliminary evaluation revealed that 44.51 kg/d SCFAs could be supplied as the electron donor for denitrification, significantly reducing the cost in ECS addition for most wastewater treatment plants (WWTPs) with carbon insufficiency. [ABSTRACT FROM AUTHOR]

• A novel upflow microaerobic sludge reactor was constructed. • The removal efficiencies of NH 4 +-N and TN reached 90.53% and 80.77%, respectively. • AOB, NOB, anammox, autotrophic and heterotrophic denitrifiers cooperated in UMSR. • Partial denitrification/anammox was dominant nitrogen conversion pathway. • The small height waterfall was applicable to treat low strength NH 4 +-N wastewater. A novel falling water aeration-external reflux upflow microaerobic sludge reactor (UMSR) was designed to treat wastewater with the low chemical oxygen demand (COD) to total nitrogen (TN) ratio. The result showed the concentration of dissolved oxygen (DO) in the reactor could be accurately controlled by adjusting the reflux ratio of oxygenated water. The higher aeration efficiency in pollutant removal could be obtained by the reoxygenation mode of the small height falling water. At the reflux ratio of 5:1, the ammonium, nitrite and nitrate nitrogen concentrations in the effluent of UMSR were 6.0, 0.4 and 6.1 mg/L on average, respectively. The removal efficiency of ammonium nitrogen and total nitrogen reached 90.53% and 80.77%, respectively with the influent COD/TN as being 1.0. The structure of the microbial community confirmed the existence of partial-denitrification/anaerobic ammonium oxidation (anammox) bacteria, autotrophic and heterotrophic denitrifiers contributed to nitrogen and carbon removal in UMSR. [ABSTRACT FROM AUTHOR]

The heat induced self-welding of nanomaterials is an important method for the artificial design and synthesis of heterogeneous composite materials. The connection and growth of solid-state crystalline nanomaterials under heat treatment normally follow the oriented attachment growth mechanism. However, there is a lack of systematic research on the interface crystallography under such formation conditions, especially for crystals with relatively large structure differences. In this work, hydrothermally grown TiO2 (B) (TB) nanofibers are chosen as examples to investigate the welded interface structure and crystallography between the same and different TiO2 polymorphs. Through the manipulation of calcination temperature, TB–TB and TB–anatase (TA) self-welded nanofiber pairs can be firstly obtained. The transmission electron microscopy (TEM) results suggest that two TB nanofibers with the same {100} single crystal form (SCF) can be connected with the same orientation or by being rotated along the fiber growth direction for certain angles. In addition, the TB nanofibers with different SCFs can also be welded through the extension and growth of (010)TB. For TB–TA self-welded pairs, the welding direction is confirmed along the long axis direction of the fiber, which is different from that of TB–TB self-welded pairs. Moreover, it is proved that the TB nanofibers with both SCFs can be welded with TA, leading to the formation of two different interfaces with typical orientation relationships. Furthermore, fewer dislocations can be found in the welded pairs with the {100} SCF of TB, which is due to the similar distribution of the voids between TiO6 octahedra for TB and TA with the orientation relationships of [010]TB//[010]TA, [100]TB//[100]TA and [106]TB//[001]TA. For the self-welded cases between TA nanofibers, the mutual rotation along different axes followed by the attachment growth was considered to be the mechanism of different interface formations. The results of this work can provide useful experimental support for the controlled synthesis of heat induced self-welded metal-oxide nanofibers. [ABSTRACT FROM AUTHOR]

Waste activated sludge (WAS) is a promising phosphorus (P) source for fertilizer production; however, it is mainly enmeshed inside microbial cells or extracellular polymeric matrixes. Thus, efficient P release is a key goal. This study provided an effective route to simultaneously release organic P (OP) and harvest hydrogen from WAS via bio-electrolysis assisted with prefermentation system (AD_MEC). The clarification of P fractions in both solid and liquid phases and the underlying mechanism in this cascading system were explored. Free nitrous acid (FNA) was employed to enhance WAS hydrolysis. The results showed that hydrogen generation was effectively accelerated: 0.54 mL per gram sludge (in volatile suspended solids (VSS)) was produced from raw WAS (AD_MEC_RWAS), which increased to 1.27 mL/g VSS from FNA-pretreated WAS (AD_MEC_FWAS). The limited OP release by prefermentation was enhanced via MECs; additionally, it was further promoted by FNA, and the treatment time was also shortened. The maximum OP release efficiency reached 54.6% at 112 h (AD_MEC_FWAS). Additionally, non-apatite and inorganic apatite P may regenerate in MECs due to the localized decrease in pH caused by hydrogen generation. This work may provide a scientific basis to enhance P and hydrogen co-recovery from WAS in forthcoming implementation. Image 1 • H 2 recovery and P release from WAS was achieved in cascading conversion system. • The limited OP release in prefermentation was accelerated via bio-electrolysis. • FNA played a positive effect on H 2 recovery and OP release from WAS. • Underlying mechanism of cascading conversion system for P release was explored. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fe anode achieved 101–743% higher of hydrogen productivity than other iron sources. • Fe anode led complete removal of phosphate within 2 d (vs. 0–39.4% in other groups). • More crystalline vivianite particles were observed in EF system assisted by Fe anode. • Homo-acetogens (78.0%), EAB (8.0%) and DIRB (2.3%) were enriched in Fe anode group. • Correlation and syntrophy between functional microbes and metabolites were explored. Electro-fermentation (EF) is a promising technology for extracting valuable metabolites from waste biomass, while its effectiveness for phosphorus recovery has received little attention. In this study, we investigated the impact of different iron sources, i.e., FeCl 3 , FeOOH, Fe 2 O 3 , zero-valent iron (ZVI), a built-in Fe anode, and stainless-steel mesh (SSM), on concurrent biohydrogen and vivianite (Fe 3 (PO 4) 2 ·8H 2 O) recovery from sludge fermentation liquid (SFL) in an EF system. Results indicated that the Fe anode group achieved the highest hydrogen productivity of 17.7 mmol/g COD at 5 d, which was 101–743% higher than that of other iron sources. The utilization efficiency of short-chain fatty acids (SCFAs) peaked at 79.1% within 5 d, which was 1.2 folds higher than that of Control (without iron addition). Moreover, the phosphate removal efficiency reached 100% within 2 d and 5 d in Fe anode and SSM group, respectively, while the other groups achieved only 0–39.4% removal. SEM and XRD analyses demonstrated the existence of vivianite particles in the recovered products in the groups of FeCl 3 , FeOOH and Fe anode. Electrochemically active bacteria (EAB), e.g., Geobacter , Comamonas , and Desulfovibrio , accounted for 3.6–60.2% of all groups. Geobacter , Azospira , Comamonas , and Desulfovibrio , which are also considered dissimilatory iron reducing bacteria (DIRB), were enriched to 0.1–40.7% in all groups. Acetoanbacterium and Acetoaerobium , typical homo-acetogens, were enriched to 78.0% in the Fe anode group, while was only 9.0–29.3% in other groups. Correlation and molecular ecological network (MEN) analyses of the functional microbial consortia further indicated the intertrophic interaction. This study provides a theoretical basis for synchronous hydrogen and phosphorus recovery from WAS in the further industrial implementation. [ABSTRACT FROM AUTHOR]

• Bi 3 O 4 Br/Ti 3 C 2 Schottky junction with efficient charge transfer was prepared. • The effect of charge transfer on active species generation was discussed. • The Bi 3 O 4 Br/Ti 3 C 2 exhibited excellent photocatalytic degradation activity of bisphenol A. Enhanced photocatalytic active species generation is an important strategy for tuning its visible-light photocatalytic activity, which is highly related to the separation and transfer of photogenerated charge carriers. In this study, we successfully prepared a novel Bi 3 O 4 Br/Ti 3 C 2 two-dimensional/two-dimensional (2D/2D) Schottky junction with special interfacial charge transfer channel via in-situ growth of Bi 3 O 4 Br on the surface of ultrathin Ti 3 C 2. The relevant characterization results indicated that Bi 3 O 4 Br/Ti 3 C 2 had a stable structure and tight interface binding, which shortened the distance of charge transfer, promoted the separation of photogenerated electron-hole pairs, and then enhanced the generation of active species. Therefore, the optimized photodegradation activity and TOC removal efficiency of Bi 3 O 4 Br/Ti 3 C 2 on Bisphenol A (BPA) could reach 91.26% and 70.97% within 60 min visible-light irradiation, respectively. Furthermore, intermediate products and BPA degradation pathways were determined. This work provides a new protocol for the construction of 2D/2D heterojunction photocatalytic systems and regulating photocatalytic active species generation by electronic effective transporting. [ABSTRACT FROM AUTHOR]

Graphical Abstract Highlights • First investigated the high COD/NO 3 −-N ratio of indole wastewater in mixed culture. • Through nitrate to observe the denitrification and methanogenesis co-existence. • Nitrate was found to facilitate indole degradation and inhibit methane formation. • The metabolites were identified based on 13C-indole isotope analysis. • A dynamic community analysis was presented to study the microbial structures. Abstract Batch experiments were conducted to investigate the effect of nitrate on indole degradation characteristics and methanogenesis under mixed denitrification and methanogenesis culture for the first time. The degradation characteristics were studied under various nitrate concentrations. Nitrate was found to facilitate indole degradation and inhibit methane formation, and the optimum concentration was 50 mg L−1 (COD/NO 3 −-N = 12). Balance analyses showed that nitrate mainly affected indole-C, which generated a higher degree of indole mineralization under NO 3 −-N treatment than in the control. Furthermore, GC–MS combined with 13C-isotope analyses conclusively identified the intermediate metabolites, which included the hydroxylated compounds oxindole and isatin, and the methylated compound 3-methylindole. The results indicated that oxindole did not accumulate and was quickly reduced when nitrate was added, but 3-methylinole, as a recalcitrant material, accumulated without reduction. High-throughput sequencing technology was used to analyse the dynamic microbial community. Results showed that the denitrifying bacterial genera Acinetobacter , Candidimonas and Longilinea accumulated in denitrification stage and decreased in methanogenesis stage, whereas the fermentation genera Alcaligenes and Thermogutta increased in methanogenesis stage. The genera Methanosphaerula and Methanothrix constituted the dominant archaeal communities. The findings obtained in this work may provide a theoretical basis for treatment with N-heterocyclic compounds under mixed culture. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A novel up-flow microaerobic granular sludge reactor was constructed. • NH 4 +-N and TN removal averaged 92.35% and 90.41%, respectively, at a low C/N ratio. • Nitrifiers, denitrifiers, and anammox bacteria thrived in the microaerobic system. • An ecological nitrogen conversion model of granule sludge was proposed. Abstract In this study, a novel upflow microaerobic sludge reactor (UMSR) was constructed to conduct anaerobic digestion of municipal wastewater with low carbon and nitrogen ratio (C/N). Oxygen in the UMSR was supplied by falling water and external recirculation. Excellent nitrogen removal performance was obtained in the UMSR for treating wastewater with low C/N ratio at a temperature of 25 °C and a hydraulic retention time of 24 h. Ammonium and total nitrogen removal efficiencies averaged 92.35% and 90.41%, respectively, and sludge granulation occurred during acclimation. The inferred metabolism of nitrogen removal and ecological positions of functional microbe were integrated into a granule model by scanning electron microscopy. Additionally, the analysis of microbial community indicated that aerobic nitrifying bacteria and heterotrophic bacteria survived on the surface of sludge floc and granules while the anaerobic autotrophic, heterotrophic denitrifying, and anaerobic ammonia oxidation bacteria were present in the inner layer. [ABSTRACT FROM AUTHOR]

[Display omitted] • Wastepaper-flora slow-release carbon was prepared for in-situ fermentation. • The prepared carbon source had self-adaptability to NO 3 –-N concentration. • A stable layered microbial structure was formed by the prepared carbon source. • The presence of the carbon source limited the growth of polysaccharides in sludge. Using wastepaper as external carbon sources is an optional way to achieve total nitrogen removal faced with low carbon to nitrogen ratio municipal sewage. Most of studies have primarily focused on using cellulose-rich wastes establishing the separate denitrification units to achieve in-situ fermentation, which can cause blockages and prolong the process chain. In response, a novel in-situ fermentation wastepaper-flora slow-release carbon source (IF-WF) was proposed using in the original denitrification unit. IF-WF could be efficiently utilized in situ and the denitrification rate increased with the increase of nitrate nitrogen. The fermentation products were highly available, but internal acidification of IF-WF inhibited fermentation. Moreover, IF-WF limited the growth of polysaccharides in the extracellular polymeric substances of denitrified sludge. IF-WF finally formed the structure dominated by nitrate-reduction bacteria outside and cellulose-degrading bacteria inside. These results provide guidance for understanding the mechanism of IF-WF for in-situ fermentation to promote nitrogen removal. [ABSTRACT FROM AUTHOR]

Zero valent iron (ZVI) is a low-cost, earth-abundant reactive metal, and it has a strong reducing ability with a standard redox potential of − 0.44 V. Therefore, it is an effective and widely used reducing agent for pollutant degradation. Since nanoscale zero valent iron (nZVI) shows a larger specific surface area which leads to the faster reaction rate and higher conversion efficiency, it has been widely used in NO 3 − nitrogen reduction reaction, however, it shows disadvantages of poor chemical stability, narrow applicable pH, and low total nitrogen (TN) removal efficiency. To solve these problems, in this paper, the nZVI nanoparticles were deposited on the g-C 3 N 4 /rGO composite, and its NO 3 − removal efficiency under visible light irradiation was investigated. The effects of nZVI loading, initial pH of solution, catalyst dosage and initial NO 3 − concentration on NO 3 − reduction performance were studied. The results showed that the g-C 3 N 4 /rGO/nZVI material achieved 100% of NO 3 − reduction efficiency in 60 min. And the TN removal efficiency of g-C 3 N 4 /rGO/nZVI was 82.8%, superior to nZVI and g-C 3 N 4 /nZVI (13.3% and 38.2%, respectively). Finally, the denitrification mechanism of g-C 3 N 4 /rGO/nZVI was proposed as follows: Under light irradiation, the photogenerated electrons on g-C 3 N 4 transferred via rGO to the nZVI surface, thus improving the reactivity and stability of nZVI. The photogenerated electrons and active electrons on the surface of nZVI reduced NO 3 − to N 2 , NH 4 +, and other products, while the photogenerated holes further oxidized part of NH 4 + to N 2 and other gaseous products. During this process, the rGO material could inhibit the oxidation of nZVI by the photogenerated holes from g-C 3 N 4. [Display omitted] • g-C 3 N 4 /rGO serves as a support for nZVI to enhance its stability and activity. • The rGO in g-C 3 N 4 /rGO hindered the oxidation of nZVI by photogenerated holes. • The NO 3 − reduction mechanism was explored and the reduction products were analyzed. • NO 3 − was completely removed and the selectivity of gaseous products were 82.8%. [ABSTRACT FROM AUTHOR]

Deposition of bimetals on Z-scheme photocatalysts has been reported to improve the nitrate nitrogen (NO 3 −) reduction properties. However, it is not clear whether bimetal deposition possesses advantage over single metal deposition and what is the different reaction mechanisms. In this work, the g-C 3 N 4 (Pd-Cu)/rGO/TiO 2 and g-C 3 N 4 (Ag)/rGO/TiO 2 composites with bimetallic Pd-Cu and single metal Ag deposited on the graphitic carbon nitride/reduced graphene oxide/titanium dioxide (g-C 3 N 4 /rGO/TiO 2) Z-scheme photocatalyst were prepared, and their photocatalytic NO 3 − reduction properties and the mechanisms under visible light irradiation were studied. The results showed that the NO 3 − and total nitrogen (TN) removal efficiencies of g-C 3 N 4 (Pd-Cu)/rGO/TiO 2 were 57.78% and 20.1%, respectively, 1.15 and 1.72 times higher than those of g-C 3 N 4 (Ag)/rGO/TiO 2. This can be ascribed to that Pd-Cu enriched more electrons and absorbed more NO 3 − molecules due to the different charge densities, and the NO 3 − reduction process were enhanced by the staged NO 3 −→NO 2 − and NO 2 −→N 2 /NH 4 + processes on Cu and Pd. The effects of reductive species were demonstrated to be photogenerated electrons > ·OH (·CO 2 −) > ·O 2 − in g-C 3 N 4 (Ag)/rGO/TiO 2 , while it was photogenerated electrons > ·O 2 − > ·OH (·CO 2 −) in g-C 3 N 4 (Pd-Cu)/rGO/TiO 2 , which may be caused by the better O 2 reduction property of the latter. Finally, the cyclic experiment proved the good stability of both materials. This work provided some reference for design of metal deposited Z-scheme photocatalysts for various reduction reactions. [Display omitted] • The g-C 3 N 4 (Cu-Pd)/rGO/TiO 2 and g-C 3 N 4 (Ag)/rGO/TiO 2 composites were prepared. • The NO 3 − reduction performances and mechanisms were studied and compared. • The reductive species in g-C 3 N 4 (Ag)/rGO/TiO 2 were e– > ·OH (·CO 2 −) > ·O 2 −. • The reductive species in g-C 3 N 4 (Cu-Pd)/rGO/TiO 2 were e– > ·O 2 − > ·OH (·CO 2 −). [ABSTRACT FROM AUTHOR]

Most studies have employed aeration-biofiltration process for the simultaneous removal of iron, manganese and ammonia in groundwater. However, what's inside the 'black box', i.e., the potential contribution of functional microorganisms behavior and interactions have seldom been investigated. Moreover, little attention has been paid to the correlations between environmental variables and functional microorganisms. In this study, the performance of industrial-scale biofilters for the contaminated groundwater treatment was studied. The effluent were all far below the permitted concentration level in the current drinking water standard. Pyrosequencing illustrated that shifts in microbial community structure were observed in the microbial samples from different depths of filter. Microbial networks showed that the microbial community structure in the middle- and deep-layer samples was similar, in which a wide range of manganese-oxidizing bacteria was identified. By contrast, canonical correlation analysis showed that the bacteria capable of ammonia-oxidizing and nitrification was enriched in the upper-layer, i.e., Propionibacterium, Nitrosomonas, Nitrosomonas and Candidatus Nitrotoga. The stable biofilm on the biofilter media, created by certain microorganisms from the groundwater microflora, played a crucial role in the simultaneous removal of the three pollutants. [ABSTRACT FROM AUTHOR]

Current studies have employed various chemicals for disintegrating and hydrolyzing microbial cells in waste activated sludge (WAS). However, a comprehensive process assessment over the whole anaerobic digestion process has seldom been proposed. Besides, the characterization of microbial community responses to these chemicals is not well understood. In this study, the effects of five typical chemicals: solubilizer (β-cyclodextrin, CD), alkaline (NaOH), peroxide (peracetic-acid, PA), biological (rhamnolipid, RL) and chemical (sodium dodecylsulphate, SDS) surfactants on WAS digestion were examined. Higher efficiencies of WAS solubilization, hydrolysis and acidification were achieved by CD treatment, followed by RL and SDS. Methanogenesis was also strongly chemicals-dependent. Shifts in microbial community structure were observed in all chemical-pretreated WAS. The community in RL, CD and PA was dominated by microorganisms that anaerobically hydrolyze organics to acids, while that in NaOH and SDS was mainly associated to biogas production. This study proved that the overall performance of WAS digestion was substantially depended on the initial chemical pretreatments, which in turn influenced and was related to the microbial community structures. Although the economic advantage might not be clear yet, the findings obtained in this work may provide a scientific basis for the potential implementation of chemicals for WAS treatment. [ABSTRACT FROM AUTHOR]

The investigation into the degradation of alkylphenol pollutants (APs) has become a hotspot due to their harmful effects on the environment and human health. In this study, microbial electrolysis cells (MECs) were used to degrade nonylphenol (NP) and 4- tert -octylphenol (4- tert -OP). The study found that the degradation rates of NP and 4- tert -OP for a 6-day period were 83.6% and 96.3%, respectively, which were 30.53% and 26.7% higher than those of the group without applied voltage. The double layer area in the degradation of 4- tert -OP was larger than that of NP, and the resistance exhibited by 4- tert -OP (87.47 Ω) in MEC was lower than that of NP (99.42 Ω). Meanwhile, NP had a greater effect on the bioenzyme activity than 4- tert -OP. GC-MS analysis showed that the degradation pathways of both pollutants mainly included oxidation and hydroxylation reactions. Furthermore, the microbial community analysis indicated that the main functional bacteria in NP degradation were Citrobacter , Desulfovibrio and Advenella , and those in 4- tert -OP degradation were Stenotrophomonas , Chryseobacterium , Dokdonella , and the key microbiomes underlying the cooperative relationship. The biotoxicity test indicated that the toxicity of residual substances was significantly reduced. Therefore, the MEC system is efficient and environmentally friendly and has broad application prospects in phenol refractory organics. [Display omitted] • Degradation ability of NP/4- tert -OP as the sole carbon source in MECs was first evaluated. • The degradation rate of NP and 4- tert -OP was effectively improved by weak electrical stimulation. • 4- tert -OP showed superior electrochemical performance and low impact on bioenzyme activity. • The main metabolic pathways of NP and 4- tert -OP were oxidation and hydroxylation reactions. • The correlation between aromatic compounds degrading bacteria and exoelectrogens was existed. [ABSTRACT FROM AUTHOR]

Excessive acidification and low methane (CH 4) percentage are technical challenges restricting anaerobic digestion (AD) of kitchen waste, especially under high organic loading rate (OLR) conditions. Although the contribution of Fe0 powder to excessive acidification elimination and CH 4 yield improvement in mesophilic AD (MAD) has been extensively reported, its impact on the thermophilic AD (TAD) process with more frequent excessive acidification problem is rarely studied. Moreover, the difference in microbial interactions and metabolic pathways between MAD and TAD reactors under Fe0 regulation was still unclear. In this study, we compared the performance of Fe0 dosing on excessive acidification elimination and biogas upgrading quality in both MAD and TAD reactors at different OLRs. The results showed that compared with excessive acidification or low CH 4 percentage (less than 70%) in control reactors without Fe0 addition, the CH 4 yield of MAD and TAD reactors with addition of Fe0 at OLR of 35 gVS/L were 470.88 mLCH 4 /gVS and 270.40 mLCH 4 /gVS, with higher CH 4 composition of 81.32%–82.23% and 83.68%–88.48% respectively. Microbial diversity analysis showed a sharp distinction between MAD and TAD reactors with addition of Fe0. Analyses of co-occurrence networks and metabolic pathway presented hydrogenotrophic methanogenic pathway, in addition to acetoclastic methanogenesis, was dominant in MAD reactors as results of enhanced interspecies hydrogen transfer between Methanoculleus and some hydrogen producers, especially under high OLR condition. In contrast, syntrophilic acetate oxidization - hydrogenotrophic methanogenesis, which dominated by Methanothermobacter and Alkaliphilus or Pelotomaculum , was the sole methanogenic pathway in TAD reactors. The results will shed lights on the regulation mechanisms of Fe0 in AD of kitchen waste under mesophilic and thermophilic conditions, offering new insight into development of more efficient waste to energy conversion technologies. [Display omitted] • Fe0 in-situ upgraded CH 4 percentage around 85% in both MAD and TAD reactors. • At OLR of 35 gVS/L, CH 4 yields of MAD and TAD reactors were 470.88 and 270.40 mLCH 4 /gVS. • Fe0 played more important role in determining microbial consortia in MAD than TAD. • Methanoculleus and Methanothermobacter produced CH 4 in MAD and TAD respectively. • IHT was key pathway for eliminating acidification in MAD, but it is SAO-HM in TAD. [ABSTRACT FROM AUTHOR]

The effects of chemosynthetic and biological surfactants on accelerating hydrogen generation from waste activated sludge (WAS) is investigated in a short-cut fermentation-bioelectrochemical system. The specific experiments are conducted in a series of completely stirred tank reactors (CSTRs) and single-chamber microbial electrolysis cells (MECs). Results shows that rhamnolipid (RL) lead to a VFAs yield 1.16-fold and 3.63-fold higher over with sodium dodecylsulphate (SDS) and sodium dodecyl benzene sulfonate (SDBS) treatments in CSTRs on 72 h. By contrast, the corresponding conversion efficiency of methanogenesis is inhibited (0.18 ± 0.03% versus 1.89 ± 0.15% (SDS) and 6.63 ± 0.77% (SDBS)), which is beneficial for subsequent hydrogen production in MECs. The distribution of the acidogenesis metabolites is also affected by the types of surfactants, reflected on cascade changing of hydrogen production. Highest hydrogen yield is 12.90 mg H 2 g −1 VSS in RL-MECs, which is larger than all values that have been reported for fermentation and single-chamber MECs. Current and electrochemical impedance spectroscopy clearly demonstrate the important role of RL treatment in electron/proton transfer and the internal resistance decrease. This study demonstrate the sustainability and attractiveness of WAS short-cut fermentation-elelctrohydrogenesis, providing a sound basis for sludge stabilization and bioenergy recovery. [ABSTRACT FROM AUTHOR]

This study aimed to extract orthophosphate (ortho-P) from lipid-rich waste AF liquor (AFL) by Mg/Al layered double hydroxides (Mg/Al LDHs) adsorption, evaluate the influence of carbonate and investigate adsorption mechanisms. The carbonate influence experiment using synthetic P-rich wastewater indicated that low carbonate level was favorable for P extraction by LDHs. And then, real AFL rich in volatile fatty acids (VFAs), carbonate and ortho-P was applied as adsorbate to explore the Mg/Al LDHs adsorption performance. Experimental results indicated that 4 g/L Mg/Al LDHs could extract 88.3% of ortho-P from the AFL with low carbonate level (4829.83 mg CaCO 3 /L), and the adsorption quantity was 62.99 mg P/g LDHs, however, negligible VFAs were extracted. Kinetics and mechanisms analysis indicated that adsorption of P onto Mg/Al LDHs was a rapid physiochemical process, including ion exchange and surface adsorption. Finally, the nutrients release test confirmed the slow-release property of intercalated P. [Display omitted] • Mg/Al LDHs acted as adsorbent to collect P from anaerobic fermentation liquor. • More than 88% of orthophosphorus was captured by 4 g/L Mg/Al LDHs. • Ion exchange and surface adsorption were the main adsorption mechanisms. • Low carbonate level was favorable for P and volatile fatty acids separation by LDHs. [ABSTRACT FROM AUTHOR]

Bioelectrochemical systems were proposed as a promising approach for the efficient valorization of biomass into 6–8 carbon atom medium-chain fatty acids (MCFAs), the precursors for high value-added chemicals or renewable energy, via acetyl-CoA-mediated chain elongation (CE). To achieve CE processes, exogenous electron donors (EDs), e.g., ethanol or lactic acid, were normally prerequisites. This research built a microbial electrolysis cell (MEC) for MCFAs biosynthesis from acetate without exogenous EDs addition. A wide range of applied voltages (0.6–1.2 V) was first employed to investigate the bioelectrocatalyzing response. The results show that caproate and butyrate were the main products formed from acetate under different applied voltages. Maximum caproate concentration (501 ± 12 mg COD/L) was reached at 0.8 V on day 3. Under this applied voltage, hydrogen partial pressure stabilized at about 0.1 bar, beneficial for MCFA production. Electron and carbon balances revealed that the electron-accepting capacity achieved 32% at 0.8 V, showing the highest interspecies electron transfer efficiency. Most of the carbon was recovered in the form of caproate (carbon loss was 9%). MiSeq sequencing revealed Rhodobacter and Clostridium_sensu_stricto playing the crucial role in the biosynthesis of caproate, while Acetobacterium , Acetoanaerobium , and Acetobacter represented the main ED contributors. Four available flora, i.e., homo-acetogen, anaerobic fermentation bacteria, electrode active bacteria, and nitrate-reducing bacteria, interacted and promoted caproate synthesis by molecular ecological network analysis. [Display omitted] • Optimal applied voltages for caproate production in MECs was firstly elucidated. • Hydrogen/ethanol in situ generated served as EDs without exogenous EDs addition. • Electron acceptability, carbon balance and hydrogen partial pressure were analyzed. • Caproate concentration and specificity achieved maximum under 0.8 V. • Synergistic and competitive interactions among functional microflora were revealed. [ABSTRACT FROM AUTHOR]

[Display omitted] • WO 3 -CuFe 2 O 4 Z-scheme catalyst was constructed. • Quinoline removal was realized by persulfate-assisted photocatalytic process. • Photogenerated holes and ·OH were the main reactive species. • Degradation mechanism and pathways of quinoline were explored. Quinoline is a kind of organic pollutant difficult to be biodegraded, for which the photocatalysis technology is a commonly used removal method, but the degradation performance still needs to be improved. In this work, the WO 3 -CuFe 2 O 4 Z-scheme system was constructed, and the persulfate (PS)-assisted photocatalytic degradation of quinoline with WO 3 -CuFe 2 O 4 by adding persulfate in the photocatalytic systems was studied. The effects of different systems and key parameters such as catalyst dosage, PS concentration and initial pH value on the degradation efficiency of quinoline were investigated. With the addition of persulfate, the degradation efficiency of quinoline increased from 24.3% to 100% in 150 min, under the condition of [PS] = 3 mmol/L, [catalyst] = 3 g/L, temperature = 25 ± 2 °C, and pH = 9. And the WO 3 -CuFe 2 O 4 catalyst showed excellent reusability according to the result of 5-cycle repeated experiment. The possible degradation mechanism was studied by the quenching test and the identification of intermediates and products, which indicated the degradation of quinoline in WO 3 -CuFe 2 O 4 /VIS/PS system was realized via denitrification, dehydrogenation, hydroxylation and ring breaking processes. [ABSTRACT FROM AUTHOR]