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[Display omitted] • The embedding immobilization improved anaerobic stability and VFA content. • Inorganic conversion of DON and DOP reached >98 % during long-term operation. • HAc and HPr notably accumulated, serving as key carbon sources for denitrification. • Shorter HRT favoured short-chain VFAs accumulation and prevented methanogenesis. • Biofillers enhanced functional bacteria, improving organic matter degradation. This study evaluated the effectiveness of embedding immobilization technology in wastewater treatment and its capacity to enhance the hydrolysis acidification process. Based on this technology, a stable anaerobic environment has been maintained. Results showed that the rates of dissolved organic nitrogen (DON) and dissolved organic phosphorus (DOP) conversion both exceeded 98 % under short hydraulic retention time (HRT = 2h) and ambient temperature. Notably, acetic acid and propionic acid comprised up to 90.9 % of the total volatile fatty acids in the effluent, providing suitable carbon sources for downstream denitrification. 16S rRNA gene sequencing indicated that biofillers effectively enriched and retained functional bacteria, causing norank_Anaerolineaceae (11.6 %-29.7 %) and norank_Bacteroidetes_vadinHA17 (10.8 %-14.9 %) as the dominant genera in the reactor, which were crucial for refractory organic matter degradation. Immobilized biofillers effectively improved wastewater biodegradability, supporting a stable microbial community with high DON and DOP conversion rates as well as increased VFA accumulation. [ABSTRACT FROM AUTHOR]

Nanobubbles (NBs) technology has been proven to promote methane production from anaerobic digestion (AD). In this study, the synergistic effects of (CH 4  + CO 2 )-nanobubble water ((CH 4  + CO 2 )-NBW) combined with varying particle sizes of corn straw on the AD were investigated. As findings, adding (CH 4  + CO 2 )-NBW effectively promoted the methane production from AD of corn straw with different particle sizes. The maximum cumulative methane yield (186.42 mL/ g-volatile solids) was achieved in Group a with the addition of (CH 4  + CO 2 )-NBW, representing a 16.89 % increase compared to the control. Furthermore, (CH 4  + CO 2 )-NBW could enhance the enzymatic activity. The activities of β-glucosidase and coenzyme F 420 were increased by 6.70 % and 11.48 %, respectively. The results of microbial community structure revealed that the addition of (CH 4  + CO 2 )-NBW could improve the abundance of dominant bacteria (norank_JS1, norank_Aminicenantales, and Bacteroidetes_vadinHA17) and archaea (Methanomassiliicoccaceae, Methanobacteriaceae, and norank_Bathyarchaeia). This study provides new insights into the application of nanobubbles in the AD of biomass., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Based on a novel bio-degumming system, the effect of chitosan on the degumming effect of ramie was investigated. The degumming effect indexes before and after the addition of chitosan were assessed, and the enzyme activities (pectinase, xylanase, ligninase and cellulase) were detected. Meanwhile changes in microbial community structure were evaluated. Furthermore, the electron-donating effect of chitosan and cellulose was further simulated by Fukui function. Degumming effect indexes showed the addition of chitosan could effectively increase the breaking strength of degummed ramie (from 6.04 to 6.59 cN/dtex), reduce the fineness (from 10.06 to 8.039 dtex), so that more gums were removed (the residual gum ratio reduced from 16.55 % to 12.09 %) and more cellulose was retained in the degummed ramie (cellulose content increased from 78.01 % to 80.96 %). Enzyme activity measurements revealed that the addition of chitosan increased the activity of degumming enzymes (pectinase, xylanase and ligninase), while decreased cellulase activity. The addition of chitosan induced changes of the community structure, with an increase of degumming microorganisms and a decrease of cellulose-degrading microorganisms. According to Fukui function, chitosan has a stronger electron donating ability than cellulose, which might be one important reason for the changes in enzyme activities and community structures., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Biofilms offer a solution to the challenge of low biomass retention faced in mainstream partial nitritation/Anammox (PN/A) applications. In this study, a one-stage PN/A reactor derived from initial granular sludge was successfully transformed into a biofilm system using shedding carriers. Environmental stressors, such as ammonium nitrogen concentration and organic matter, significantly affected the competitive dynamics and dominant species composition between Ca. Kuenenia and Ca. Brocadia. Under approximately 500 mg/L NH 4 + -N, Ca. Brocadia emerged as the dominant anammox bacteria species, but was subsequently replaced by Ca. Kuenenia in the presence of approximately 54 mg COD/L CH 3 COONa. Moreover, Chloroflexi species on the original biofilm exhibited an associated relationship with the growth of Ca. Kuenenia in new biofilm. The biofilm assembly and microbial community migration uniquely reveal the microbial niche dynamics. This study provides valuable insights for PN/A biofilm applications facing diverse challenges of environmental stresses in the transition from sidestream to mainstream., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

The anammox process is efficient for nitrogen removal but faces challenges due to slow bacterial growth and limited inoculated sludge supply. This study examined the effects of different inoculated sludge concentrations (3.5, 7, and 14 g/L) on start-up and nitrogen metabolism in anammox reactors. Three identical reactors were operated under controlled conditions, with comprehensive analysis of nitrogen removal efficiency, sludge characteristics, and microbial community dynamics through metagenomic and transcriptomic approaches. Results demonstrated that higher inoculated sludge concentrations accelerated reactor start-up, with the 14 g/L reactor achieving stable operation in 13 days compared to 44 days for the 3.5 g/L reactor. However, the improvement in nitrogen removal rate showed a boundary effect, not proportional to the increase in sludge concentration. Notably, reactors with higher inoculated sludge concentrations exhibited lower sludge loads but higher sludge yield coefficients. Metagenomic analysis revealed Candidatus Kuenenia as the dominant anammox bacteria, with decreasing hydrazine dehydrogenase (hdh) gene expression levels observed at higher sludge concentrations, suggesting hydrazine synthesis as a potential rate-limiting step. This study provides novel insights into the optimal range of inoculated sludge concentration for anammox reactor start-up and elucidates the underlying metabolic mechanisms, offering valuable guidance for practical engineering applications., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

[Display omitted] • PLAs were applied to substitute traditional CCM in denitrification biofilters. • Replacing CCM with PLA enhanced nitrate removal from 32.68-54.39% to 41.64–66.26%. • Denitrifier enriched on PLA plastisphere preferred to inhabit or degrade PLA. • PLA enhanced the enrichment of genes related to nitrogen and carbon metabolism. • Bacillus strain P01 isolated from PLA plastisphere demonstrated PLA degradation. Developing methods for reusing biodegradable plastics, like polylactic acid (PLA) straws, is highly needed. Here, PLAs were applied to substitute traditional commercial ceramic media (CCM) in denitrification biofilters. During long-term operation, replacing CCM with PLA significantly enhanced nitrate removal efficiency from 32.68–54.39 % to 41.64–66.26 %. Ammonia nitrogen effluent maintained below 0.5 mg/L in all reactors. PLA plastisphere shaped unique microbial communities, i.e., denitrifying bacteria Bacillus , Pseudomonas and Acidovorax preferred to inhabit or degrade PLA. Compared to CCM biofilms, PLA diminished the importance of stochastic process in biofilm assembly of PLA plastisphere. Metagenomic sequencing suggested that PLA biofilms possessed greater metabolic capabilities of denitrification and glycolysis compared to CCM. Additionally, Bacillus strain P01 isolated from PLA plastisphere demonstrated strong PLA depolymerization. Overall, this study revealed that PLA serves as carbon source and biofilm carrier, offering a promising approach to integrating plastic reuse with wastewater treatment. [ABSTRACT FROM AUTHOR]

[Display omitted] • Anammox was effective in treating high ammonium photovoltaic wastewater (PVW). • The process stability decreased with influent nitrogen concentration reached 200 mg/L. • Increasing ammonium concentration breaks hydrogen bond and tyrosine peak disappears. • Candidatus Kuenenia is more tolerant to high ammonium PVW than other AnAOBs. Tunnel Oxide Passivating Contacts (TOPcon) battery in the photovoltaic industry generates high ammonium wastewater during the production process, the adaptability of using the anaerobic ammonia oxidation (Anammox) process for photovoltaic wastewater (PVW) treatment is a research hotspot. Based on the analysis of photovoltaic wastewater quality, the effectiveness of nitrogen removal, sludge characteristics and microbial communities were examined. The results showed that when the influent NH 4 +-N concentration of PVW was lower than 150 mg·L−1, the nitrogen removal efficiency (NRE) was almost 100 %. In addition, the NRE decreased from 74 % sharply to 20 % when the NH 4 +-N concentration was increased from 175 mg·L−1 to 200 mg·L−1. The extracellular polymeric substances (EPS) content increased with elevated ammonium concentration in the influent, indicating that microorganisms secreted more EPS to resist elevated nitrogen loading. The main functional populations were Candidatus Kuenenia (0–24 %). The influent ammonium concentration is recommended to be < 200 mg·L−1. [ABSTRACT FROM AUTHOR]

[Display omitted] • Microplastics and phthalate were the highest in food waste extruded biogas residue. • Microplastics with size of < 0.2 mm in each stage exceeded 70 %. • Positive correlations were found between microplastics and phthalate. • Microorganisms with microplastics degradation capabilities were present. Food waste (FW) and its biogas residue were considered as sources of terrestrial microplastics (MPs) and phthalic acid esters (PAEs) contamination. However, there was a lack of research and understanding of the MPs and PAEs pollution problem in FW dry anaerobic digestion process (DADP). The MPs and PAEs in three stages of the DADP with the largest monomer disposal scale in China were identified. At the biogas residue extrusion stage, MPs abundance and PAEs concentration reached the highest values, which were 3.63 ± 0.45 × 103 N·kg-1 and 3.62 ± 0.72 mg·kg-1, respectively. Furthermore, there was a significant positive correlation between MPs and PAEs throughout the process (p < 0.05). Although bacteria and fungi with plastic degradation potential were present in all stages, the contamination problem of MPs and PAEs cannot be completely solved through DADP. This study provides a scientific basis for preventing and controlling the pollution of MPs and PAEs. [ABSTRACT FROM AUTHOR]

[Display omitted] • Triclosan enhanced volatile fatty acids accumulation and inhibited methanogenesis. • Solubilization, hydrolysis, and acidogenesis were improved by triclosan. • Triclosan increased acid production enzyme activity, and decreased coenzyme F420. • Triclosan migrated direction was solid → liquid → solid during anaerobic digestion. Triclosan (TCS), a hydrophobic antibacterial agent, is extensive application in daily life. Despite a low biodegradability rate, its hydrophobicity results in its accumulation in waste-activated sludge (WAS) during domestic and industrial wastewater treatment. While anaerobic digestion is the foremost strategy for WAS treatment, limited research has explored the interphase migration behavior and impacts of TCS on WAS degradation during anaerobic digestion. This study revealed TCS migration between solid- and liquid-phase in WAS digestion. The solid–liquid distribution coefficients of TCS were negative for proteins and polysaccharides and positive for ammonium. High TCS levels promoted volatile-fatty-acid accumulation and reduced methane production. Enzyme activity tests and functional prediction indicated that TCS increased enzyme activity associated with acid production, in contrast to the inhibition of key methanogenic enzymes. The findings of the TCS migration behavior and its impacts on WAS anaerobic digestion provide an in-depth understanding of the evolution of enhanced TCS-removing technology. [ABSTRACT FROM AUTHOR]

[Display omitted] • Performance of BE-UASB treating high-sulfate methanolic wastewater was evaluated. • BE-UASB exhibited COD removal of 93.6 % with 1.4-fold CH 4 yield of control. • Humics as main components of EPS on electrodes benefited the electron transfer. • Electrocatalysis induced synergy between Acetobacterium and SRB to reduce SO 4 2−. • BE-UASB restructured MPA to alleviate the competition with SRB for electron donors. A bioelectrochemical upflow anaerobic sludge blanket (BE-UASB) was constructed and compared with the traditional UASB to investigate the role of bioelectrocatalysis in modulating methanogenesis and sulfidogensis involved within anaerobic treatment of high-sulfate methanolic wastewater (COD/SO 4 2− ratio ≤ 2). Methane production rate for BE-UASB was 1.4 times higher than that of the single UASB, while SO 4 2− removal stabilized at 16.7%. Bioelectrocatalysis selectively enriched key functional anaerobes and stimulated the secretion of extracellular polymeric substances, especially humic acids favoring electron transfer, thereby accelerating the electroactive biofilms development of electrodes. Methanomethylovorans was the dominant genus (35%) to directly convert methanol to CH 4. Methanobacterium as CO 2 electroreduction methane-producing archaea appeared only on electrodes. Acetobacterium exhibited anode-dependence, which provided acetate for sulfate-reducing bacteria (norank Syntrophobacteraceae and Desulfomicrobium) through synergistic coexistence. This study confirmed that BE-UASB regulated the microbial ecology to achieve efficient removal and energy recovery of high-sulfate methanolic wastewater. [ABSTRACT FROM AUTHOR]

[Display omitted] • Biochar enhances CO 2 capture, increasing the solubility by up to 25.8 mmol/L. • CO 2 concentrated with biochar improves cumulative methane yield by 24 % maximally. • Exogenous CO 2 reduces ΔG overall by approximately double. • Exogenous CO 2 can enhance RET, in which the CO 2 can be converted into formate. • Biochar-concentrated CO 2 enrichs syntrophic bacteria and their partner M. hungatei. Acid accumulation and carbon emission are two major challenges in anaerobic digestion. Syntrophic consortia can employ reverse electron transfer (RET) to facilitate thermodynamically unfavorable redox reactions during acetogenesis. However, the potential mechanisms and regulatory methods of RET remain unclear. This study examines the regulatory mechanisms by which exogenous CO 2 affects RET and demonstrates that biochar maximizes CO 2 solubility at 25.8 mmol/L to enhance effects further. CO 2 synergized with biochar significantly increases cumulative methane production and propionate degradation rate. From the bioenergetic perspective, CO 2 decreases energy level to a maximum of −87 kJ/mol, strengthening the thermodynamic viability. The underlying mechanism can be attributed to RET promotion, as indicated by increased formate dehydrogenase and enrichment of H 2 /formate-producing bacteria with their partner Methanospirillum hungatei. Moreover, the 5 % 13CH 4 and methane contribution result show that CO 2 accomplishes directed methanogenesis. Overall, this investigation riches the roles of CO 2 and biochar in AD surrounding RET. [ABSTRACT FROM AUTHOR]

[Display omitted] • Two-chamber MEC-AD with Fe-AnGS as inoculum achieved biogas upgrading. • Inoculation of Fe-AnGS in MEC-AD improved ERR C by 23%–29%. • Hydrogenotrophic methanogenesis dominated in the cathode chambers of MEC-AD. • The enriched energy and electron transfer related genus promotes DIET pathway. The productivity and efficiency of two-chamber microbial electrolysis cell and anaerobic digestion integrated system (MEC–AD) were promoted by a complex of anaerobic granular sludge and iron oxides (Fe–AnGS) as inoculum. Results showed that MEC–AD with Fe–AnGS achieved biogas upgrading with a 23%–29% increase in the energy recovery rate of external circuit current and a 26%–31% decrease in volatile fatty acids. The energy recovery rate of MEC–AD remained at 52%–57%, indicating a stable operation performance. The selectively enriched methanogens and electroactive bacteria resulted in dominant hydrogenotrophic and acetoclastic methanogenesis in the cathode and anode chambers. Mechanistic analysis revealed that MEC–AD with Fe–AnGS led to specifically upregulated enzymes related to energy metabolism and electron transfer. Fe–AnGS as inoculum could improve the long-term operation performance of MEC–AD. Consequently, this study provides an efficient strategy for biogas upgrading in MEC–AD. [ABSTRACT FROM AUTHOR]

[Display omitted] • MgFe 2 O 4 and Ca 0.5 Mg 0.5 Fe 2 O 4 NPs were synthesized to improve bioH 2 yield. • MgFe 2 O 4 and Ca 0.5 Mg 0.5 Fe 2 O 4 NPs lowered the negative effects of humic acids. • MgFe 2 O 4 NPs enriched Clostridium_sensu_stricto_1 more than Ca 0.5 Mg 0.5 Fe 2 O 4 NPs. • MgFe 2 O 4 NPs improved bioH 2 yield higher than Ca 0.5 Mg 0.5 Fe 2 O 4 NPs. Dark fermentation (DF) is an eco-friendly process that simultaneously achieves organic matter degradation and obtains hydrogen (H 2). Nonetheless, low H 2 yield mainly caused by poor activity of key microbes, is still a problem that requires being resolved. In this work, MgFe 2 O 4 and Ca 0.5 Mg 0.5 Fe 2 O 4 nanoparticles (NPs) were synthetized and served as additives to boost H 2 form from DF. H 2 productivity gradually increased with the rise of NPs, and declined when NPs exceeded their optimal dosages. The highest H 2 yield was 183.6 ± 3.2 mL/g glucose at 100 mg/L of MgFe 2 O 4 NPs, being 35.2 % higher than that of the control yield (135.8 ± 3.1 mL/g glucose). However, the highest H 2 yield of 171.9 ± 2.5 mL/g glucose occurred at 400 mg/L of Ca 0.5 Mg 0.5 Fe 2 O 4 NPs, increasing by 26.6 % over the control. Interestingly, the two NPs favored the butyric acid pathway for H 2 synthesis. This provides guidance for multi-element oxide NPs used in DF. [ABSTRACT FROM AUTHOR]

[Display omitted] • NH 4 +-N in 2000 mg/L got the highest nitrogen-removal rates and enzymatic activities. • Abundance of HN-AD bacteria was 50 %, 62 %, 82 % in 500, 1000, 2000 mg/L NH 4 +-N. • High-strength NH 4 +-N availed to Acinetobacter's contribution to nitrogen removal. • The mechanism of HN-AD bacteria with high NH 4 +-N tolerance were firstly depicted. This work aimed to elucidate the metabolic mechanism of heterotrophic nitrification-aerobic denitrification (HN-AD) bacteria influenced by varying concentrations of ammonium nitrogen (NH 4 +-N) in high-strength synthetic wastewater treatment. The results showed that the removal rates of NH 4 +-N and total nitrogen, along with enzymatic activities related to nitrification and denitrification, increased with rising NH 4 +-N concentrations (N 500 :500 mg/L, N 1000 :1000 mg/L and N 2000 :2000 mg/L). The relative abundances of HN-AD bacteria were 50 %, 62 % and 82 % in the three groups. In the N 2000 group, the cAMP signaling pathway, glycerophospholipid metabolites, purines and pyrimidines related to DNA/RNA synthesis, electron donor NAD+-related energy, the tricarboxylic acid (TCA) cycle and glutamate metabolism were upregulated. Therefore, influent NH 4 +-N at 2000 mg/L promoted glutamate metabolism to accelerate the TCA cycle, and enhanced cellular energy and advanced denitrification activity of bacteria for HN-AD. This mechanism, in turn, enhanced microbial growth and the carbon and nitrogen metabolism of bacteria for HN-AD. [ABSTRACT FROM AUTHOR]

• PN filler performance under high and low ammonia, and low temperature was evaluated. • PN filler can be rapidly reactivated after reactor breakdown or long stagnation. • Immobilization facilitated functional bacteria growth and community dominance. • The mechanism for the high efficiency and stability of the PN filler was explained. • The oxygen permeation depth model of the PN filler was established. Long-term high efficiency and stable partial nitrification (PN) performance was achieved using gel-immobilized partial nitrifying bacteria. The PN characteristics of the filler under high and low ammonia nitrogen concentrations and low temperature were comprehensively studied and the rapid reactivation was achieved after reactor breakdown or long stagnation period. The results showed that the maximum ammonia oxidation rate was 66.8 mg•(L•h)−1 and the nitrite accumulation rate was above 95 % for the filler. Efficient and stable PN performance depends on the high abundance of ammonia-oxidizing bacteria (AOB) inside the filler and dynamically microbial community. In addition, the oxygen-limited zone and competition between the microorganisms inside the filler effectively inhibited the growth of nitrite oxidizing bacteria, and the sludge outside the filler assisted in this process, which supported the dominant position of AOB in fillers. This study provides a reliable technology for the practical application of the PN nitrogen removal process. [ABSTRACT FROM AUTHOR]

[Display omitted] • Increase of PFAS level adversely affected the AD system and microbial activity. • PFOA led to higher impacts on AD performance and microbial activity than PFOS. • Archaeal group was more vulnerable to both PFOA and PFOS than bacterial group. • PFOA induced changes in microbial community by their toxicity. • PFOS induced changes in microbial community by their toxicity and functional group. Per- and polyfluoroalkyl substances (PFASs) are recalcitrant organic pollutants, which accumulate widely in aquatic and solid matrices. Anaerobic digestion (AD) is one of possible options to manage organic wastes containing PFASs, however, the impacts of different types of PFAS on AD remains unclear. This study aimed to critically investigate the effects of two representative PFAS compounds, i.e., perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS), on the AD performance and microbial community structure. 100 mg/L of both PFOA and PFOS considerably inhibited the AD performance and changed the microbial community structure. Especially, PFOA was more toxic to bacterial and archaeal activity than PFOS, which was reflected in AD performance. In addition, the sulfonic acid group in PFOS affected the changes in microbial community structure by inducing abundant sulfate reducing bacteria (i.e., Desulfobacterota). This study provides a significant reference to the response of AD system on different PFAS types and dosage. [ABSTRACT FROM AUTHOR]

Highlights • Microalgal consortia were enriched from aerobic (AeS) and anaerobic (AnS) sludges. • Both the consortia grew well on four different anaerobic digestion (AD) effluents. • The AeS cultures showed faster and greater microalgal growth on all the effluents. • The AnS cultures showed similar or faster NH 4 +-N removal rate on all the effluents. • N starvation significantly influenced the lipid production and community structure. Abstract This study examines the potential of the mixed-culture microalgal consortia enriched from aerobic sludge (AeS) and anaerobic sludge (AnS) with regard to nutrient removal and biomass production from four different anaerobic digestion (AD) effluents. Both the inocula achieved the complete removal of the NH 4 +-N (initial concentration of 40 mg/L) within 14 days from all the effluents. The AeS cultures showed faster and greater microalgal growth, although the NH 4 +-N removal rate was comparable or higher in the case of the AnS cultures. Further, the AeS and AnS cultures showed significantly different lipid production characteristics in terms of the fatty acid composition and the response to nitrogen deficiency. Nitrogen starvation caused changes in the microbial community structures in all the experimental cultures, which may have influenced the lipid metabolism and the microalgal growth. The overall results suggest that both the inocula exhibit good potential with regard to the treatment of AD effluents. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Highest nitrogen removal was achieved at 20 °C in the hybrid CANON reactor. • Performance was not always deteriorated with temperature reduction. • Activities of key enzymes were analyzed with temperature reduction. • The factors for maintaining nitrogen removal performance varied with temperature. Abstract Recently, a flocculent-granular hybrid reactor was reported as a novel nitrogen removal system; however, the mechanisms of stable operation in the system remain unclear. In this study, the mechanisms of the stable nitrogen removal performance in a flocculent-granular hybrid system were investigated with temperature reduction. The operational period was divided into three phases with different temperatures ranges. In phase I, the nitrogen removal efficiency was stabilized at about 90% with nitrogen removal load maintained at approximately 0.28 kg N/(m3·day). In phase II, while decreasing the temperature to 20 °C, the activities of key enzymes were reduced immediately and were then maintained at a certain level. The relative abundances of aerobic ammonium-oxidizing bacteria and anaerobic ammonium-oxidizing bacteria gradually increased at this phase. In phase III, after the temperature dropped to 15 °C, the activities of key enzymes gradually increased due to adaptation to low temperature, boosting the nitrogen removal efficiency to 83%. [ABSTRACT FROM AUTHOR]

Highlights • Enhanced simultaneous long-term P and N removals in A-TFCW were achieved. • Denitrifying bacteria in A-TFCW accounted for 45.19% higher than S-TFCW (22.14%). • Novel AA substrate could be applied in TFCW for treatment of domestic wastewater. Abstract A tidal flow constructed wetland (TFCW), a commonly applied system to clean wastewater, contains a substrate to assist pollutants removal, while the choice of substrate affects the formation of bacterial biofilms. Herein, activated alumina-TFCW (A-TFCW) with hydraulic load of 1.35 m3/(m2·d) parallel with shale ceramisite (S-TFCW) was investigated for treating domestic wastewater, aiming to enhance simultaneous long-term removal of organics, nitrogen and phosphorus. A-TFCW achieved significantly higher COD, NH 4 +-N, TN and TP removal efficiency than S-TFCW, with the removal efficiency of 85.9% COD, 85.4% NH 4 +-N, 72.8% TN and 96.4% TP respectively. Denitrifying bacteria dominated in both formed biofilms, with higher relative abundance of nitrifying bacteria and denitrifying bacteria in A-TFCW. These results demonstrated that AA substrate was more suitable to be applied in enhancing the removal performance in TFCW for the treatment of domestic wastewater. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The combined heterotrophic and autotrophic process was investigated in ABR. • A high perchlorate reduction rate was obtained by step-feeding strategy. • The combined heterotrophic and autotrophic process decreases sulfate production. • The tryptophan-like materials can promote heterotrophic perchlorate sludge activity. • Relationships between dominant microbes and the environment were found by PCA. Abstract The combined anaerobic baffled reactors (ABRs) of heterotrophic and sulfur-based autotrophic processes were first investigated for the removal of high perchlorate concentration under different feeding strategies. The removal efficiency of the step-feeding ABR (SF-ABR) reached 97.56% at 800 mg/L perchlorate, which was significantly superior to the normal-feeding ABR (NF-ABR). In three components of the extracellular polymeric substances (EPS), the fluorescence intensity of the tryptophan-like component were identified by fluorescence excitation–emission matrix (EEM) spectra with parallel factor (PARAFAC) analysis, and exhibited a positive relationship with the perchlorate removal rate in the heterotrophic perchlorate reduction unit (HPR unit) of the SF-ABR (R 2 = 0.9791) and NF-ABR (R 2 = 0.9860). Bacterial community analysis suggested the dominating perchlorate reducing bacteria and the diversity in two ABRs. Principal component analysis indicated that the electron donor affected the microbial community structures. The study confirms that the SF-ABR is a powerful bioreactor for the combined heterotrophic and sulfur-based autotrophic process. [ABSTRACT FROM AUTHOR]

Highlights • The use of certain anion/cation exchange membranes in MFC is first presented. • The type of membrane separator affected the efficiency of MFC start-up. • MFC with anion exchange membrane showed outstanding performance. • Geobacter was dominantly selected on anodes independently of membrane type. • Voltammograms indicated various anode surface coverage of redox components. Abstract In this study, microbial fuel cells (MFCs) – operated with novel cation- and anion-exchange membranes, in particular AN-VPA 60 (CEM) and PSEBS DABCO (AEM) – were assessed comparatively with Nafion proton exchange membrane (PEM). The process characterization involved versatile electrochemical (polarization, electrochemical impedance spectroscopy – EIS, cyclic voltammetry – CV) and biological (microbial structure analysis) methods in order to reveal the influence of membrane-type during start-up. In fact, the use of AEM led to 2–5 times higher energy yields than CEM and PEM and the lowest MFC internal resistance (148 ± 17 Ω) by the end of start-up. Regardless of the membrane-type, Geobacter was dominantly enriched on all anodes. Besides, CV and EIS measurements implied higher anode surface coverage of redox compounds for MFCs and lower membrane resistance with AEM, respectively. As a result, AEM based on PSEBS DABCO could be found as a promising material to substitute Nafion. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The endurance to ammonia toxicity of sludge was enhanced by hydrogen enrichment. • Phenol degradation and methanogenic activity were improved with the increase of HPP. • Syntrophic interactions were well established under high ammonia concentration. • Three hydrogen-consuming pathways were simulated by hydrogen enrichment. Abstract Phenol and ammonia are prevalent toxic pollutants in various industrial wastewaters, but phenol degraders are frequently inhibited by high concentration of ammonia. Hydrogen enrichment was developed to alleviate ammonia inhibition on anaerobic digestion of phenol-containing wastewater. Results indicated that the endurance to ammonia of sludge was improved greatly by hydrogen enrichment at higher ammonia concentration (from 2 to 8 g NH 4 +-N/L) compared with the control group. Furthermore, phenol utilization rate of sludge was gradually enhanced with the increase of initial hydrogen partial pressure (HPP) at ammonia concentration of 2 g NH 4 +-N/L and the maximum rate of 199.75 mg/g VSS/d was achieved under 0.8 atm HPP. The maximum SMA of acetate and hydrogen was 0.61 and 0.45 g COD-CH 4 /g VSS/d, respectively under 0.8 atm HPP. Three hydrogen-consuming pathways including homoacetogenesis, hydrogenotrophic methanogenesis and benzoate generation played the critical roles in enhancing anaerobic digestion of phenol by hydrogen enrichment under high ammonia concentration. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Perchlorate reducing granular sludge (DPR-GS) was first cultivated in UASB. • DGS maintained the nucleus stability and directly served as carriers for DPR-GS. • The fluctuating up-flow velocity strategy can alleviate biomass loss. • Sulfurospirillum and Acinetobacter were the dominant DPRB. Abstract To remove high-strength perchlorate, dissimilatory perchlorate reducing granular sludge (DPR-GS) was first cultivated. Three identical UASB reactors were set up under different seed sludge and up-flow velocities (R AS : active sludge (AS) and constant up-flow velocities; R DGS : denitrifying granular sludge (DGS) and constant up-flow velocities; R DGS-f : DGS and fluctuating up-flow velocities). The AS in the R AS was completely granulated by day 117, while the DGS in the R DGS and R DGS-f were both shortened the granulation time to 99 days. In addition, the fluctuating up-flow velocity can better ensure rapid cultivation of DPR-GS. Removal of ClO 4 − loading rate with 7.20 kg/(m3·d) occurred in all three reactors. The results of extracellular polymeric substances (EPS) composition analysis indicated the polysaccharose (PS) promoted the formation of bio-aggregates, while the protein (PN) benefited the granulation of sludge. The analyses of the microbial communities indicated that Sulfurospirillum and Acinetobacter were the dominant dissimilatory perchlorate reducing bacteria. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • UCPs were first used to stimulate nitrogen removal of periphytic biofilms. • UCPs optimized the microbial community structure of periphytic biofilms. • Periphytic biofilms simulated by UCPs could adapt to nitrogen fluctuation. Abstract The application of periphytic biofilm in removing nitrogen from water is limited by the fluctuating nitrogen concentration. Here, we delineate a novel approach to enhance periphytic biofilm performance in nitrogen removal via upconversion luminescence of upconversion phosphors (UCPs). Nitrogen removal rates (14 d) in high nitrogen wastewater (26 mg/L) were significantly improved to 58.6% and 61.4% by UCPs doped with Pr3+ and Li+ and UCPs doped with Pr3+, respectively, and to 95.1% and 95.9% in low nitrogen surface water (2 mg/L), respectively. The stimulation of UCPs optimized the microbial community structure in the periphytic biofilms, and also resulted in good acclimation to use different carbon sources. The enhanced synergic action of cyanobacterial biomass, ratio of Gram +ve to Gram −ve bacteria and carbon source metabolic capacity contributed to the improved nitrogen removal. This novel approach is promising in nitrogen removal from wastewater and surface water with fluctuating initial nitrogen concentration. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • On-site treatment of saline black water (BW) was successfully conducted for ship. • Saline BW treated by bioaugmentation on-site marine bacteria with P. sp. SCSE709-6. • Inoculum of P sp. SCSE709-6 had positive effects to COD and TP removal. • The similarity of microbial communities increased by inoculum of P. sp. SCSE709-6. • NH 4 + removal relevant to Klebsiella , TP removal correlated to Pseudoalteromonas. Abstract To reduce fresh water load on ships, seawater can be used for toilet flushing on-board. And saline black water was treated on-site by bioaugmentation original marine bacteria with Pseudoalteromonas sp. SCSE709-6 (P. sp. SCSE709-6) to prevent marine pollution. In the batch experiments, P. sp. SCSE709-6 was effective in nutrient removal, which was not closely related to the amount of inoculation. In the on-board continuous experiments, the systems inoculated with P. sp. SCSE709-6 possessed excellent TP removal ability (removal rate: 80.93% for T3 and 88.39% for T4). The inoculum of P. sp. SCSE709-6 changed the microbial community structure and increased the similarity of microbial communities. P. sp. SCSE709-6 had a significant influence on the performance and microbial community of the systems. This study strongly proposes that the P. sp. SCSE709-6 is a promising alternative in saline black water treatment, which has great significance to the practice of on-board seawater flushing toilet. [ABSTRACT FROM AUTHOR]

[Display omitted] • An economical material (Fe/C containing 40% siliceous material) was synthesized. • The new material exhibited an excellent nitrogen removal efficiency. • Diversity and richness of denitrifying bacterial communities were enhanced. • The abundance of key denitrification enzymes increased significantly. • Anaerobic denitrification of sediments jointly assisted nitrogen removal. Aerobic denitrification technology can effectively abate the nitrogen pollution of water source reservoirs. In this study, 40% siliceous material was used as the carrier to replace the activated carbon in Fe/C material to enhance denitrification and purify water. The removal efficiency of new material for target pollutants were nitrate nitrogen (95.68%), total phosphorus (68.23%) and chemical oxygen demand (46.20%). Aerobic denitrification of water samples and anaerobic denitrification of sediments in three systems jointly assisted nitrogen removal. In a reactor with new material, diversity and richness of denitrifying bacterial communities were enhanced, and the symbiotic structure of aerobic denitrifying bacteria was more complex (Bacillus and Mycobacteria as the dominant bacteria); the microbial distribution better matched the Zif and Mandelbrot models. This system significantly increased the abundance of key enzymes in water samples. The new material effectively removed pollutants and represents a promising and innovative in-situ remediation method for reservoirs. [ABSTRACT FROM AUTHOR]

[Display omitted] • PN and DN performance could maintain stability under high FA conditions. • Nitrosomonas exhibited strong tolerance to high levels of FA (1099.8 mg/L). • Microbial community dynamics of PN could make community resistant to the FA impact. • High levels of FA had scant impact on the microbial community and performance of DN. The high levels of free ammonia (FA) challenge the application of partial nitritation (PN) and denitrification (DN) in the treatment of ammonia-rich wastewater. This study explored the impact of high levels of FA on the PN and DN stability and microbial community dynamics. By reducing reflux and increasing influent load, the concentrations of FA in PN and DN reactors increased from 28.9 mg/L and 140.0 mg/L to 1099.8 mg/L and 868.4 mg/L, respectively. During this process, the performance of PN and DN remained stable. The microbial analysis revealed that the Nitrosomonas exhibited strong tolerance to high levels of FA, and its relative abundance was positively correlated with amoABC (R2 0.984) and hao (R2 0.999) genes. The increase in microbial diversity could enhance the resistance ability of PN against the FA impact. In contrast, high levels of FA had scant influence on the microbial community and performance of DN. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A high perchlorate reduction rate was obtained by step-feeding. • Sulfate concentration can be decreased by step-feeding. • The biodiversity along the height of reactor was decreased by step-feeding. • Relationships between primary microbes and environment were analyzed. Abstract Excess sulfate production and low concentration of perchlorate removal are the main problems for sulfur-based perchlorate reduction reactor. In this study, the problems were firstly solved by step-feeding under mixotrophic conditions. The performances of step-feed sulfur-based reactor (SFSBR) and up-flow sulfur-based reactor (UFSBR) are compared. At perchlorate of 194 mg/L, acetate of 28.8 mg/L and hydraulic retention time of 0.9 h, the Half-order reaction rate constant and the sulfate production of SFSBR were 29.7 mg1/2/L1/2·h and 171 mg/L, respectively, which were superior to those of UFSBR. The oxidation-reduction potential values of SFSBR were lower than that of UFSBR. Meanwhile, the biodiversity along the height of the reactor was decreased by step-feeding. Principal component analysis showed significant interrelations existed among the bacterial community composition and the operational/environmental conditions in each treatment zone. Consequently, the SFSBR provides an effectively alteration for the removal of high perchlorate concentration and control sulfate. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Anammox bacterial was enriched in SBR system under lower nitrogen load. • 15–26 °C constitutes breaking point for nitrogen removal in the Anammox SBR. • Temperature variation can affect Anammox bacteria community structure. • Ca. Kuenenia is more adaptive to varied temperature than Ca. Brocadia. Abstract The nitrogen removal performance and microbial communities of an Anammox sequencing batch reactor (SBR) was studied under varied temperatures with a lower nitrogen loading rate (NLR) about 0.28 kgN/m3/d. Results showed that the temperature could influence the nitrogen removal performance and the community structure in the Anammox SBR system. Under lower temperatures, both the nitrogen removal efficiencies and Anammox activity were in lower levels. When temperature was raised again, the Anammox activity recovered accordingly. When the temperature dropped from 33 ± 1 °C to15 °C, the dominant Anammox bacteria shifted from Ca. Brocadia to Ca. Kuenenia in the sludge. When the temperature returned over, the abundance of Ca. Brocadia recovered, while the Ca. Kuenenia was still the dominant Anammox bacteria. This indicated that Ca. Kuenenia is more adaptable to low temperature environment than Ca. Brocadia under low NLR with temperature variation. [ABSTRACT FROM AUTHOR]

Thermal hydrolysis (TH) pretreatment was investigated for the anaerobic digestion (AD) of a mixture of high-strength organic wastes (i.e., dewatered human feces, dewatered sewage sludge, and food wastewater) at laboratory scale to simulate a full-scale plant and evaluate its feasibility. The reactors maintained efficient and stable performance at a hydraulic retention time of 20 days, which may be not sufficient for the mesophilic AD of high-suspended-solid wastes, despite the temporal variations in organic load. The addition of FeCl 3 was effective in controlling H 2 S and resulted in significant changes in the microbial community structure, particularly the methanogens. The temporary interruption in feeding or temperature control led to immediate performance deterioration, but it recovered rapidly when normal operations were resumed. The overall results suggest that the AD process coupled with TH pretreatment can provide an efficient, robust, and resilient system to manage high-suspended-solid wastes, supporting the feasibility of its full-scale implementation. [ABSTRACT FROM AUTHOR]

The present study investigates the conversion of acetate, propionate and hydrogen consumption linked to the microbial community structure and related to temperature and substrate concentration. Biogas reactors were continuously fed with coffee powder (20 g-COD/L) or acetate (20, 40, and 60 g-COD/L) and operated for 193 days at 37 °C or 55 °C conditions. Starting HRT was 23 days which was then reduced to 7 days. The kinetics of acetate and propionate degradation and hydrogen consumption rates were measured in batch assays. At HRT 7 days, the degradation rate of propionate was higher in thermophilic batches, while acetate degradation rate was higher at mesophilic conditions. The gaseous hydrogen consumption in acetate reactors increased proportionally with temperature and substrate concentration, while the dissolved hydrogen was not affected. The relative high abundance of hydrogentrophic methanogens indicated that the methanogenesis was directed towards the syntrophic acetate oxidation pathway at high acetate concentration and high temperature. [ABSTRACT FROM AUTHOR]

An anaerobic ceramic membrane bioreactor (AnCMBR) has been attracted as an alternative technology to co-manage various organic substrates. This AnCMBR study investigated process performance and microbial community structure at decreasing temperatures to evaluate the potential of AnCMBR treatment for co-managing domestic wastewater (DWW) and food waste-recycling wastewater (FRW). As a result, the water flux (≥6.9 LMH) and organic removal efficiency (≥98.0%) were maintained above 25 °C. The trend of methane production in the AnCMBR was similar except for at 15 °C. At 15 °C, the archaeal community structure did not shifted, whereas the bacterial community structure was changed. Various major archaeal species were identified as the mesophilic methanogens which unable to grow at 15 °C. Our results suggest that the AnCMBR can be applied to co-manage DWW and FRW above 20 °C. Future improvements including psychrophilic methanogen inoculation and process optimization would make co-manage DWW and FRW at lower temperature climates. [ABSTRACT FROM AUTHOR]

This study compared two anammox sequencing batch reactors (SBR) for one year. SBR constantT was kept at 30 °C while temperature in SBR loweringT was decreased step-wise from 30 °C to 20 °C and 15 °C followed by over 140 days at 12.5 °C and 10 °C. High retention of anammox bacteria (AnAOB) and minimization of competition with AnAOB were key. 5-L anoxic reactors with the same inoculum were fed synthetic influent containing 25.9 mg NH 4 + -N/L and 34.1 mg NO 2 − -N/L (no COD). Specific ammonium removal rates continuously increased in SBR constantT , reaching 785 mg NH 4 + -N/gVSS/d, and were maintained in SBR loweringT , reaching 82.2 and 91.8 mg NH 4 + -N/gVSS/d at 12.5 and 10 °C respectively. AnAOB enrichment (increasing hzsA and 16S rDNA gene concentrations) and adaptation (shift from Ca. Brocadia to Ca. Kuenenia in SBR loweringT ) contributed to these high rates. Rapidly settling granules developed, with average diameters of 1.2 (SBR constantT ) and 1.6 mm (SBR loweringT ). Results reinforce the potential of anammox for mainstream applications. [ABSTRACT FROM AUTHOR]

The NO 3 − removal pathway and microorganisms change along with the height of an up-flow W-SPD bioreactor was investigated in this study. Modeling and microbial community analysis were used to analyze the denitrification behavior in W-SPD bioreactor. The results showed that NO 3 − removal rate matched for zero-order (R 2  > 0.97) and first-order (R 2  > 0.94) combination Michaelis-Menten kinetics, whereas microbial reaction rate suited for modified logistic model (R 2  > 0.99). The excellent denitrification performance (92.5%–96.4%) and microorganisms’ quantity occurred in the middle of W-SPD bioreactor. Moreover, high-throughput sequencing analysis revealed that dominant denitrifiers, carbonaceous compound degrading bacteria and fermentative bacteria co-existed in W-SPD system, which was vital for efficiently sustainable NO 3 − removal. Hence, aerobic degradation, heterotrophic denitrification and dissimilatory nitrate reduction to ammonium (DNRA) occurred successively along the water direction in the bioreactor, offering reasonable references for W-SPD bioreactor study and application. [ABSTRACT FROM AUTHOR]

Bioaugmentation was used to upgrade the nitrification process in a full-scale municipal WWTP with an A 2 /O system. A mixture of nitrifying bacteria was inoculated into the bioreactor for a final concentration of 1% (v/v). The upgrade process took 25 days, and the NH 4 + -N removals reached 94.6% (increased at least by 75%). The effluent concentrations of COD and NH 4 + -N stabilized at <30 mg/L and <4 mg/L even when the corresponding influent concentrations were over 300 mg/L and 60 mg/L, which met the first-class requirement of the National Municipal Wastewater Discharge Standards of China (COD ≤ 50 mg/L, NH 4 + -N ≤ 5 mg/L). The succession of the microbial community showed the enhanced NH 4 + -N removal efficiency mainly resulted from the persistence of introduced ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB), which increased from 0% to 0.4% and from 0.01% to 2.1%, respectively. This bioaugmentation was shown as an effective technology for upgrading or retrofitting conventional systems to tertiary-level. [ABSTRACT FROM AUTHOR]

[Display omitted] • Molten salt carbonization is a reasonable way to obtain biochar (BC). • BioH 2 yield was enhanced by 32.4% with molten salt-modified BC (MSBC). • Mineral elements contained in MSBC contributed to biomass accumulation. • MSBC improved the electrochemical activity of anaerobic sludge. • Clostridium sensu stricto 1 and Citrobacter were enriched by MSBC. Generally, dark fermentation (DF) of hydrogen (H 2) synthesis has low H 2 production from industrial-scale plants. In this study, campus greening wastes-ginkgo leaves were used to produce molten salt-modified biochar (MSBC) and nitrogen (N 2)-atmosphere BC (NBC) in molten salt and N 2 environment at 800 °C, respectively. MSBC showed excellent properties including high specific surface area and electron transfer ability. After supplementation with MSBC, H 2 yield rose by 32.4% compared to the control group without carbon material. Electrochemical analysis revealed MSBC improved the electrochemical properties of sludge. Furthermore, MSBC optimized the microbial community structure and increased the relative abundance of dominant microbes, thus promoting H 2 production. This work provides a deep understanding of two carbons that play vital roles in increasing microbial biomass, supplementing trace element and favoring electron transfer in DF reactions. Salt recovery achieved 93.57% in molten salt carbonization, which has sustainability compared with N 2 -atmosphere pyrolysis. [ABSTRACT FROM AUTHOR]

[Display omitted] • PAN MPs enriched the secretion of extracellular polymeric substance. • Granular breakage occurred at 100 mg/L PAN MPs. • Phylum Proteobacteria played a dominant role in resistance to PAN MPs. • PAN MPs inhibited membrane transport and denitrification functional genes. Aerobic granular sludge (AGS) has proved to be a promising biotechnology for microplastics wastewater treatment. However, polyacrylonitrile microplastics (PAN MPs), the most widely used plastic in textile materials, have not been investigated. Therefore, the effect of the neglected PAN MPs on AGS at different concentrations (1, 10, and 100 mg/L) was evaluated. The results indicated that PAN MPs with 1 and 10 mg/L concentrations had no obvious effect on granular stability and nutrient removal performance, but greatly promoted the secretion of EPS. Remarkably, the granule structure was severely damaged under 100 mg/L PAN MPs. Moreover, microbial community analysis showed that phylum Proteobacteria played a dominant role in resistance to PAN MPs. Metabolic analysis further revealed that genes related to denitrification pathway (nasA, nirK, nirS and norB) and membrane transport were significantly inhibited under PAN MPs stress. This study may provide additional information on the treatment of microplastics wastewater using AGS. [ABSTRACT FROM AUTHOR]

• Assessment of biochar amendment benefits on microbial community were studied. • Coconut shell biochar and bamboo biochar bring changes to bacterial communities. • Mitigating threat of antibiotic has been solved by antibiotic resistant bacteria. • Proteobacteria, Actinobacteria, Bacteroidetes are 3 phyla with richer abundance. • Bacterial communities are conspicuously regulated by environmental factors. The study aim was to reveal the mechanism of impact of two type biochar on composting of hen manure (HM) and wheat straw (WS). Biochar derived from coconut shell and bamboo used as additives to reduce antibiotic resistant bacteria (ARB) in HM compost. The results manifested that effect of biochar amendment was significant to reduce ARB in HM composting. Compared with control, the microbial activity and abundance were increased in both biochar applied treatment, and bacterial community was changed. Additionally, network analysis revealed that biochar amendment increased the quantity of microorganisms related to organic matter degrading. Among them, coconut shell biochar (CSB) played a pioneering role to mitigate ARB to better exert its effects. Structural correlation analysis showed that CSB reduce ARB mobility and promote organic matter degradation via improving beneficial bacterial community structure. Overall, composting with participation of biochar amendment stimulated antibiotic resistance bacterial dynamics. These results evidence practical value for scientific research and lay the foundation for agricultural promotion of composting. [ABSTRACT FROM AUTHOR]

[Display omitted] • Applying voltage promoted Anammox start-up and nitrogen removal rate. • Applying voltage increased HAO/HZO activity, ETS, and EPS during Anammox. • Voltage promoted the growth of Candidatus_Kuenenia aggregated on the cathode. • Applying voltage regulates the structure and metabolism of bacterial communities. • Step-up voltage operation are more favorate for Anammox bacteria enrichment. The slow growth and difficulty in cultivating anammox bacteria limit the rapid start-up of anammox process and effective microbial enrichment. In this study, microbial electrolysis cell (MEC) was coupled with anammox to investigate the effects of different applying voltage methods on substrate removal efficiency and rates, microbial community structure, anammox metabolism and metabolic pathways. The results showed that applying voltage not only improved NH 4 +-N removal efficiency and removal rates, but also promoted electron transfer efficiency, key enzyme activity and extracellular polymeric substances (EPS) secretion in the systems. Step-up voltage was more conducive to the growth of Candidatus_Kuenenia in the cathode, which promoted the rapid start-up of anammox and treating wastewater with low ammonia concentration. The main metabolic pathway in step-up voltage operation was hydrazine to nitrogen, while in constant voltage operation was hydroxylamine oxidation pathway. These findings provided a new insight into the enhancement and operation of anammox system. [ABSTRACT FROM AUTHOR]

[Display omitted] • MAB were applied to treat saline wastewater from high to moderate and low salinities. • MAB consistently exhibited good nitrogen removal performance at 35–3.5 g/L salts. • The MAB-based anammox completely collapsed in freshwater surroundings. • Proper salts in seawater were required for MAB to remain active. Marine anammox bacteria (MAB) have promising nitrogen removal performance in high saline wastewater treatment. Nevertheless, the impact resulting from moderate and low salinities on MAB is still unclear. Herein, MAB were applied to treat saline wastewater from high to moderate and low salinities for the first time. Independent of salinities (35–3.5 g/L), MAB consistently exhibited good nitrogen removal performance, and maximum total nitrogen removal rate (0.97 kg/(m3·d)) occurred at 10.5 g/L salts. More extracellular polymeric substances (EPSs) were secreted by MAB-based consortia to resist hypotonic surroundings. However, a sharp EPS decrease was accompanied by the collapse of MAB-driven anammox process, and MAB granules disintegrated due to long-term exposure to salt-free environment. The relative abundance of MAB varied from 10.7% to 15.9% and 3.8% as salinity decreased from 35 to 10.5 and 0 g/L salts. These findings will provide practical implementation of MAB-driven anammox process treating wastewater with different salinities. [ABSTRACT FROM AUTHOR]

[Display omitted] • TCS was efficiently degraded in single- and dual-chamber BES reactors. • The initial concentration, buffer solution, and applied voltage were optimized. • Both bioanode and biocathode demonstrated substantial contributions to TCS degradation. • Hydrolysis and dechlorination were the major pathways of TCS degradation. In this work, the bioelectrochemical system (BES) is a feasible alternative for successfully degrading typical refractory emerging contaminant triclosan (TCS). A single-chamber BES reactor with an initial TCS concentration of 1 mg/L, an applied voltage of 0.8 V, and a solution buffered with 50 mM PBS degraded 81.4 ± 0.2% of TCS, exhibiting TCS degradation efficiency improvement to 90.6 ± 0.2% with a biocathode formed from a reversed bioanode. Both bioanode and biocathode were able to degrade TCS with comparable efficiencies of 80.8 ± 4.9% and 87.3 ± 0.4%, respectively. Dechlorination and hydrolysis were proposed as the TCS degradation pathway in the cathode chamber, and another hydroxylation pathway was exclusive in the anode chamber. Microbial community structure analysis indicated Propionibacteriaceae was the predominant member in all electrode biofilms, and the exoelectrogen Geobacter was enriched in anode biofilms. This study comprehensively revealed the feasibility of operating BES technology for TCS degradation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Daily anaerobic sequencing batch reactor showed efficient methane production. • Multiple operation parameters were investigated by central composite design. • A significant model (p < 0.0001) was built for predicting biogas production rate. • Inhibitions due to chemical oxygen demand accumulation were relieved. This study performed co-digestion of poultry litter (PL) with wheat straw in the daily anaerobic sequencing batch reactor considering operation parameters of carbon-to-nitrogen ratio (C/N, 11.6 to 28.4), total solids (TS, 2.6 to 9.4%), and hydraulic retention time (HRT, 7.6 to 24.4d). The inoculum with a diverse microbial community structure included 2% of methanogens (Methanosaeta) was chosen. Experimental performance by central composite design showed continuous methane production with the highest biogas production rate (BPR) obtained at C/N = 20, TS = 6%, and HRT = 7.6d, being (1.18 ± 0.14 L/L R /d). A significant modified quadratic model (p < 0.0001) for predicting BPR was built (R2 = 0.9724). The operation parameters and process stability both affected the release of nitrogen, phosphorus, and magnesium in the effluent. The results provided new support for the novel reactor operations for efficient bioenergy production from PL and agricultural wastes. [ABSTRACT FROM AUTHOR]