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The occurrence of antibiotic residues present in organic fertilizers produced by diverse techniques is largely unknown. Large-scale evaluation and standardization are imperative to identify the concentration and risks of residual antibiotics during different treatment techniques of livestock manure (i.e., compost, carbonization, and anaerobic treatment). In this study, we assessed the concentration and ecological risks of 30 antibiotics in three types of commercial organic fertilizers by the risk quotient (RQ) method. The highest levels of residual antibiotics in the organic fertilizers produced by composting, carbonization, and anaerobic treatment were 142.58 μg/kg (dry weight) oxytetracycline, 2.53 μg/kg (dry weight) oxytetracycline, and 341.86 mg/L chlortetracycline. We observed that the compost and carbon-based organic fertilizers had an RQ of less than 0.1, indicating a low risk. In contrast, liquid organic fertilizer had an RQ of 0.93, indicating a medium risk. After a comprehensive comparison and evaluation, the "carbonization + anaerobic treatment" mode was found to be more appropriate for most cases. Moreover, the preparation method of organic fertilizers needs further optimization to minimize the concentration of residual antibiotics within the range of low ecotoxicity. [ABSTRACT FROM AUTHOR]

The development of low carbon treatment processes is an important issue worldwide. Partial denitrification coupled with anammox (PD/A) is a novel strategy to remove nitrogen and reduce N 2 O emissions. The influence of C/N ratio and NH 4 + concentration on nitrogen removal and N 2 O emissions was investigated in batch reactors filled with PD/A coupled sludge. A C/N ratio of 2.1 was effective for nitrogen removal and N 2 O reduction; higher ammonia concentration might make anammox more active and indirectly reduce N 2 O emissions. Long-term operation further confirmed that a C/N ratio of 2.1 resulted in a minimum effluent N 2 O concentration (mean value of 0.94 μmol L−1); as the influent NH 4 + concentration decreased to 50 mg L−1 (NH 4 +-N/NO 3 −-N: 1), the nitrogen removal rate increased to 82.41%. Microbial analysis showed that anammox bacteria (Candidatus Jettenia and Ca. Brocadia) were enriched in the PD/A system and Ca. Brocadia gradually dominated the anammox community, with the relative abundance increasing from 1.69% to 18.44% between days 97 and 141. Finally, functional gene analysis indicated that the abundance of nirS/K and hao involved in partial denitrification and anammox, respectively, increased during long-term operation of the reactor; this change benefitted nitrogen metabolism in anammox, which could indirectly reduce N 2 O emissions. [Display omitted] • N 2 O emission can be controlled with the C/N ratio in the one-stage PD/A system. • N 2 O was low in the effluent during long-term operation at C:N ratio 2.1 and NH 4 +-N/NO 3 −-N of 1. • Anammox bacteria (Ca. Jettenia and Ca. Brocadia) were enriched with a C/N ratio of 2.1. • Ca. Brocadia gradually dominated the AnAOB consortia after day 97. • Increased NirS/K and Hao increased the activity of anammox and reduced N 2 O. [ABSTRACT FROM AUTHOR]

The catalytic ozonation treatment of secondary biochemical effluent for papermaking wastewater by Ag-doped nickel ferrite was investigated. Ag-doped catalysts prepared by sol-gel method were characterized, illustrating that Ag entirely entered the crystalline of NiFe 2 O 4 and changed the surface properties. The addition of catalyst enhanced the removal efficiency of chemical oxygen demand and total organic carbon. The results of gas chromatography-mass spectrometer, ultraviolet light absorbance at 254 nm and three-dimensional fluorescence excitation-emission matrix suggested that aromatic compounds were efficiently degraded and toxic substances, such as dibutyl phthalate. In addition, the radical scavenging experiments confirmed the hydroxyl radicals acted as the main reactive oxygen species and the surface properties of catalysts played an important role in the reaction. Overall, this work validated potential applications of Ag-doped NiFe 2 O 4 catalyzed ozonation process of biologically recalcitrant wastewater. Image, graphical abstract [ABSTRACT FROM AUTHOR]

Abstract The addition of zero-valent iron (ZVI) and ZVI & persulfate (PS) were efficient approaches to enhance the production of volatile fatty acids (VFAs), especially butyric acid, from food wastes (FW) during anaerobic fermentation. The maximal concentration of VFAs was increased from 1256 mg COD/L in the control reactor to 8245 mg COD/L with ZVI addition, and it was further improved to 9800 mg COD/L with the PS/ZVI treatment. An investigation of the mechanisms revealed that both the ZVI and PS/ZVI treatments improved the bioavailable substrates in FW and enhanced the bioconversion efficiency of fermentation substrates, especially proteins and lipids. The provision of a sufficient amount of bioavailable substrates was advantageous to the enrichment of the functional bacteria that are responsible for the production of VFAs. Additionally, the microbial activity and key metabolic enzymes involved in the biological VFAs generation processes were stimulated in the ZVI and PS/ZVI-added reactors, which jointly contributed to high-rate VFAs yields. Graphical abstract Unlabelled Image Highlights • ZVI and PS/ZVI contributed greatly to the VFAs promotion, especially butyric acid. • The bioconversion of complex organics was improved, particularly protein and lipid. • The functional acidogens for VFAs yield were enriched in ZVI and PS/ZVI reactors. • The microbial activity involved in VFAs yield was stimulated by the ZVI and PS/ZVI. [ABSTRACT FROM AUTHOR]

Two mathematical models were used to optimize the performance of a full-scale biological nutrient removal (BNR) activated treatment plant, a plug-flow bioreactors operated in a 3-stage phoredox process configuration, anaerobic anoxic oxic (A/O). The ASM2d implemented on the platform of WEST2011 software and the BioWin activated sludge/anaerobic digestion (AS/AD) models were used in this study with the aim of consistently achieving the designed effluent criteria at a low operational cost. Four ASM2d parameters (the reduction factor for denitrification $(\eta _{NO_3 H} )$, the maximum growth rate of heterotrophs (µ), the rate constant for stored polyphosphates in PAOs ( q), and the hydrolysis rate constant ( k)) were adjusted. Whereas three BioWin parameters (aerobic decay rate ( b), heterotrophic dissolved oxygen (DO) half saturation ( K), and Y/acetic) were adjusted. Calibration of the two models was successful; both models have average relative deviations (ARD) less than 10% for all the output variables. Low effluent concentrations of nitrate nitrogen (N-NO), total nitrogen (TN), and total phosphorus (TP) were achieved in a full-scale BNR treatment plant having low influent chemical oxygen demand (COD) to total Kjeldahl nitrogen (TKN) ratio (COD/TKN). The effluent total nitrogen and nitrate nitrogen concentrations were improved by 50% and energy consumption was reduced by approximately 25%, which was accomplished by converting the two-pass aerobic compartment of the plug-flow bioreactor to anoxic reactors and being operated in an alternating mode. Findings in this work are helpful in improving the operation of wastewater treatment plant while eliminating the cost of external carbon source and reducing energy consumption. [ABSTRACT FROM AUTHOR]

Different kinds of volatile fatty acids (VFAs) were used to feed denitrifying processes for comparison in this study. The acetic and propionic acid-fed processes attained the highest nitrate removal rates. The nitrite accumulation mainly occurred in the short-chain VFAs (formic, acetic and propionic acid, rather than the other three) which exhibited two denitrifying stages (fast and slow) by reaction kinetic analysis. According to parallel analysis of microbial community, the cooperation of denitrifiers and long-chain VFAs (>3C) degrading microorganisms were probably responsible for the different denitrification rates from previous study. The secondary use of degraded long chained VFAs by denitrifies would explain the interesting results that similar community structures of denitrifying bacteria responded to the similar VFAs molecular structures (based on parallel DGGE fingerprint). Real time PCR showed that the abundance of nirK genes was lower in acetic acid-fed denitrifying process than other VFAs, which agreed with its highest nitrite accumulation, indicating the acetic acid appeared to be inadequate for nirK -type denitrifiers enrichment, even though it achieved the highest nitrate reduction rate. The comparison of N 2 O accumulation and emission was further analyzed and discussed for the six reactors. [ABSTRACT FROM AUTHOR]

In this study, the activated sludge model implemented in the BioWin® software was validated against full-scale wastewater treatment plant data. Only two stoichiometric parameters ( Y and the heterotrophic yield ( Y) required calibration. The value 0.42 was used for Y in this study, while the default value of the BioWin® software is 0.49, making it comparable with the default values of the corresponding parameter (yield of phosphorus release to substrate uptake $(Y_{PO_4 } )$) used in ASM2, ASM2d, and ASM3P, respectively. Three scenarios were evaluated to improve the performance of the wastewater treatment plant, the possibility of wasting sludge from either the aeration tank or the secondary clarifier, the construction of a new oxidation ditch, and the construction of an equalization tank. The results suggest that construction of a new oxidation ditch or an equalization tank for the wastewater treatment plant is not necessary. However, sludge should be wasted from the aeration tank during wet weather to reduce the solids loading of the clarifiers and avoid effluent violations. Therefore, it is recommended that the design of wastewater treatment plants (WWTPs) should include flexibility to operate the plants in various modes. This is helpful in selection of the appropriate operating mode when necessary, resulting in substantial reductions in operating costs. [ABSTRACT FROM AUTHOR]

[Display omitted] • Granulation of PD granular sludge was achieved with the glycerol as carbon source. • The glycerol-fed PDGS showed superior settleability with efficient nitrite yield. • The proteins in T-EPS played key roles in the formation of PDGS. • The PN, PS and living cells distributed uniformly in PDGS to maintain bioactivity. • Saccharibacteria was speculated to be mainly responsible for the granulation. Granular sludge is considered as a promising technology for wastewater treatment owing to the high biomass retention and excellent settleability. In this study, the formation and underlying mechanisms of granular sludge for stable and efficient nitrite accumulation in glycerol-driven partial denitrification (PD) reactors were investigated. The PD granular sludge (PDGS) was successfully formed with developing and mature stages. The mature PDGS exhibited superior settleability (mean particle size: 468.1 μm, and SVI 5 :16.4 mL/g SS), and high microbial activity (VSS/SS: 0.80–0.92). The nitrite was stably and efficiently accumulated with an average nitrate-to nitrite transformation ratio of 87.3%. Morphological analysis showed that the mature granules were dominated by cocci and exhibited compact structure with few inorganic components. The proteins (i.e. tyrosine, tryptophan and aromatic protein-like substances) in tightly-bound extracellular polymeric substances (EPS) were expected to play critical roles in the granulation process in view of their good correlation with particle size variation. The EPS contents (mainly polysaccharides and proteins) and living cells were distributed throughout the granule, suggesting the overall high stability and bioactivity of formed PDGS. Moreover, the glycerol-driven PD reactor caused the evident evolution of microbial structure, and the significant enrichment of Saccharibacteria was expected to be responsible for the granulation process, which was increased to 66.6% in the matured sludge. This study confirmed the feasibility and superior performance of PDGS fed with glycerol. [ABSTRACT FROM AUTHOR]

The impacts of the influent type in wastewater treatment plants (WWTPs) on the distribution patterns of the microbial community and functional characteristics were investigated. The obtained results indicated that the influent types exhibited evident influences on the microbial distribution patterns. The diversity and richness of functional microbes in HI-WWTP (with a ratio of >30% industrial wastewater in influents) were evidently decreased compared with those in HM- (with 70–90% municipal wastewater in influents) and M-WWTPs (with >90% municipal wastewater in influents). The core functional bacteria included denitrifiers, anaerobic fermentation bacteria (AFB), organic degrading bacteria (ODB), phosphorus accumulating organisms (PAO) and nitrite oxidizing bacteria (NOB), but they exhibited distinct abundances in WWTPs receiving different categories of wastewater. The denitrifiers in HI-WWTPs was 15.6–32.5% higher than that in other WWTPs, while PAOs had higher abundances in M − and HI-WWTPs (28.9% and 39.3%, respectively) compared with HM-WWTPs. Clear co-occurrence relationships were found among the main functional microbes with similar metabolic characteristics. Moreover, information on functional genes related to carbon, nitrogen and phosphorus metabolism, which is closely associated with pollutant removal efficiency, was obtained. M-WWTPs had higher abundances of genetic expressions for organic matters degradation (i.e. amino acid (10.42%) and carbohydrate (9.86%) metabolisms). Nar , Nir and Nor showed lowest abundances in HM-WWTPs, causing the low nitrogen removal (63.04–65.79%). However, influent type had little effect on genetic expression related with phosphorus removal. This work provided new insights into the interrelationship among bacterial co-occurrence, microbial activity and pollutant removal in WWTPs with different influent types. [Display omitted] • Influents type is more influential on bacterial community than treatment process. • The category of functional genera is similar but with distinct abundance in WWTPs. • The microbial co-occurrence and association with pollutant removal are illustrated. • Critical microbial functions for pollutants metabolism are displayed at gene level. [ABSTRACT FROM AUTHOR]

Model simulation is an effective approach to optimize the operational performance of wastewater treatment plants (WWTPs). This study presents a novel strategy to enhance the total nitrogen (TN) removal in WWTPs by GPS-X integrated with response surface methodology. The sensitivities of 61 parameters were screened and analyzed, and 6 critical parameters (i.e., μ max A , K A/a , μ max H , K H/ss , Y H and μ maxPAO) were selected for further adjustment. The accuracy of GPS-X for WWTPs modeling was validated by static and dynamic simulations with actual operational data. The results showed that the DO concentration diffused in different biological compartments exhibited significant effects on the denitrification rate. The TN removal is also associated with SRT. The significance and optimization orders of key parameters were analyzed. With the optimization of DO in biological units and SRT, the nitrification and denitrification rates were improved to 97.1 and 85.3% respectively, saving 17.9% energy consumption. Unlabelled Image • The TN removal in WWTPs is optimized via the GPS-X simulation integrated with RSM. • Six critical parameters were found with the sensitivity analysis and screening. • The significance and optimization orders of critical parameters were recommended. [ABSTRACT FROM AUTHOR]

• High NO 2 –-N was accumulated in glycerol-driven PD reactor at C/N of 4.5 and pH 6–9. • NO 2 –-N was stably accumulated in long-term operation with an average NTR of 80.1%. • The denitrifying bacteria: Saccharibacteria (77.9%) was highly enriched. • The glycerol accelerated the metabolic rate for NO 2 –-N accumulation in PD reactor. • The disparity of NAR and NIR as well as encoding genes caused NO 2 –-N accumulation. Partial denitrification (PD), which could provide sufficient nitrite for subsequent anaerobic ammonium oxidation, is a novel strategy for mainstream nitrogen removal. In this study, the performance of using glycerol as electron donor for nitrite accumulation in PD process was evaluated. Results showed that a C/N of 4.5 was effective for nitrite production (average nitrite accumulation rate: 34.32 mg N h−1 gMLVSS-1; average nitrate-to-nitrite transformation ratio (NTR): 91.1%) with pH ranging from 6.0 to 9.0. Also, a stable nitrite accumulation was achieved in long-term operation with the average NTR of 80.1%. Mechanism investigation found that the denitrifying bacteria Saccharibacteria (77.9%) was enriched in glycerol-driven reactors. Moreover, the enzymatic activity as well as the encoding genes (i.e. narG , narH and napA) involved in nitrate reduction were much higher than that for nitrite reduction (i.e. nirK), and this disparity was responsible for the efficient nitrite accumulation in glycerol-driven PD system. [ABSTRACT FROM AUTHOR]

• Both FW composition and ZVI affected the VFAs production in semi-continuous reactors. • The bacterial community changed little with time but varied greatly in different reactors. • The metabolic functions and activities of anaerobes were linked to FW composition. • The ZVI improved the metabolic activity and abundance of functional genes for VFAs. The effects of food wastes (FW) composition and zero-valent iron (ZVI) on the volatile fatty acids (VFAs) generation, bacterial community succession and related metabolic functions during long-term FW and waste activated sludge (WAS) co-fermentation were investigated. The VFAs production in the carbohydrate-enriched reactor was approximately 3.0-folds of that in FW reactor. The ZVI contributed to the VFAs promotion by 3.6- and 6.7-folds in carbohydrate-enriched and FW reactors, respectively. Firmicutes (20.1–74.7%), Actinobacteria (0.9–26.3%), Bacteroidetes (3.4–65.7%), and Proteobacteria (9.1–28.5%) were the main bacteria in different fermentation reactors, and they were closely associated with the fermentation substrates and ZVI. Further analysis demonstrated that the key metabolic capacity (i.e. amino acid, carbohydrate and energy metabolism) and the genetic expressions of enzymes (i.e. fabA, fabZ, accA and accB) involved in VFAs generation were also related to FW composition, and were improved by the ZVI, which accounted for the significant VFAs promotion. [ABSTRACT FROM AUTHOR]

• P and VFAs were recovered efficiently and stably in long-term WAS/FW fermentation. • 82.88% P from WAS was recovered as high-purity vivianite (95.23%). • The efficiencies of Fe2+ and P release and VFAs recovery were highly linked to SRT. • The transformation of P forms during WAS/FW co-fermentation was analyzed. • The FeCl 3 and FW enriched the functional bacteria with stimulated activities. A practical approach of synchronously recovering vivianite and volatile fatty acids (VFAs) by food waste (FW) and waste activated sludge (WAS) co-fermentation in continuous operation was investigated. Approximately 82.88% P as high-purity vivianite (95.23%) and 7894 mg COD/L VFAs were finally recovered. The simultaneous addition of FW and FeCl 3 contributed to the fermentation conditions by adjusting pH biologically and increasing the concentration of organic substrates, which enhanced the Fe3+ reduction efficiency and microbial activities (e.g., hydrolases and acidogenic enzymes). Microbial analysis found the functional bacteria related to Fe3+ reduction and VFAs generation were further enhanced and enriched. Besides, results indicated that the efficiencies of Fe2+ and P release and VFAs recovery were highly linked to SRT, the satisfactory fermentation performance was obtained at SRT of 6 d. This research would provide a practical waste recycling technology to treat FW and WAS simultaneously for recovering vivianite and VFAs synchronously. [ABSTRACT FROM AUTHOR]

• Various EACs were detected in full-scale WWTPs at different levels. • The influent and main treatment process in WWTP affected the distribution of EACs. • Antidepressants are mainly removed by adsorption but it is biodegradation for EDCs. • The core degrading-bacteria for EACs biodegradation were identified. • The discharged EACs from WWTPs posed different levels of environmental risks. In this study, the distribution, removal efficiency, and potential risks of 9 typical endocrine active compounds (EACs) in two full-scale wastewater treatment plants (WWTPs) were investigated. The EAC concentrations ranged from 0.2 to 7394.2 ng/L in influents. The source of influents was a critical factor in determining the EAC levels. EACs were primarily removed in the secondary biological processing units, with removal efficiencies fluctuating from 13.7% to 98%. The biological treatment processes and operating parameters (i.e., HRT and SRT) influenced the EAC removal efficiency. Bisphenol A (BPA) and estriol were mainly removed by biodegradation, while antidepressants were primarily eliminated by sludge adsorption according to the distribution patterns and mass flow of EACs in WWTPs. Novosphingobium, Saprospiraceae, etc. were the core functional bacteria for EAC biodegradation. In addition, sertraline in effluents and dewatered sludge may pose medium environmental risks, while the other EACs pose low environmental risks. [ABSTRACT FROM AUTHOR]

• Efficient P and VFAs were synchronously recovered from WAS/FW co-fermentation. • 83.09% of the TP in WAS was recovered as high-purity vivianite (93.90%). • The WAS/FW (30%) co-fermentation with pH uncontrolled generated the highest VFAs. • WAS/FW co-fermentation contributed to the release of Fe2+ and PO 4 3− by lowering pH. • The flexible pH variation in WAS/FW reactor was favorable for microbial activity. This research proposed an innovative approach to synchronously enhance the recovery of phosphorus (P) as vivianite and volatile fatty acids (VFAs) during waste activated sludge (WAS) and food waste (FW) co-fermentation. A high performance was achieved under 30% FW addition and pH uncontrolled, which gained 83.09% of TP recovery as high-purity vivianite (93.90%), together with efficient VFAs production (7671 mg COD/L). The FW supplement could enhance VFAs production and subsequently lower pH to contribute to the release of Fe2+ and PO 4 3−. Also, it could dampen disrupting effects of strong acidic pH on microbial cells (lowering LDH release). Moreover, the flexible pH variation caused by biological acidification could maintain relatively higher microbial activities (increasing enzymes' activities), which was advantageous to the biological effects involved in Fe2+ and PO 4 3 release and VFAs generation. Therefore, this research provide a promising and economic alternative to dispose of WAS and FW simultaneously for valuable resource recovery. [ABSTRACT FROM AUTHOR]

• CASS exhibited higher N removal efficiency compared with that of A2/O or A/O. • Denitrification rate was a good alternative to assess N removal in WWTPs. • BOD 5 in influent was the most important factor in shaping microbial communities. • The core functional genera in N removal were identified by correlation analysis. The denitrification process is crucial for biological nitrogen removal in wastewater treatment plants (WWTPs). In this study, the nitrogen removal efficiency in full-scale WWTPs with different treatment processes and influent characteristics was investigated. The results indicated that the average total nitrogen removal rate (NRR) and denitrification rate in the A/O or A2/O systems were 67.5% and 2.08 mg N h−1 gMLVSS−1, respectively. However, cyclic activated sludge systems (CASSs) showed more efficient nitrogen removal with an average NRR and denitrification rate of 79.6% and 9.89 mg N h−1 gMLVSS−1, respectively. The microbial communities in WWTPs with similar influent compositions were similar and mainly shaped by BOD 5. Candidatus Competibacter , Caldilineaceae and Anaerolineaceae were the functional genera closely associated with nitrogen removal based on high-throughput sequencing and correlation analysis. This study provides new insights into the regulation and amelioration of full-scale WWTPs to meet the increasingly stringent nitrogen discharge standard. [ABSTRACT FROM AUTHOR]

• The optimal conditions for vivianite were pH 6.0–9.0, PO 4 3− >5 mg/L and Fe/P 1.5. • Most of Fe2+ and PO 4 3− were simultaneously released in FeCl 3 -pH3 dosing sludge. • Clostridiaceae was dominant in FeCl 3 -pH3 reactors that induced Fe3+ reduction. • The P recovery efficiency as vivianite from WAS fermentation could be 82.60%. This study presented an innovative method for phosphorus (P) recovery as vivianite from waste activated sludge (WAS) via optimizing iron dosing and pH value during anaerobic fermentation (AF). The optimal conditions for vivianite formation were in the pH range of 6.0–9.0 with initial PO 4 3− >5 mg/L and Fe/P molar ratio of 1.5. Notably, FeCl 3 showed advantages over ZVI for the simultaneous release of Fe2+ and PO 4 3− during WAS fermentation, especially in acidic conditions. The FeCl 3 dosing at pH 3.0 could contribute to 78.81% Fe2+ release and 85.69% of total PO 4 3− release from WAS. They were ultimately recovered in the form of high-purity vivianite (93.67%). Clostridiaceae (40.25%) was the predominant bacteria in FeCl 3 -pH3 reactors, which played key roles in inducing dissimilatory iron reduction for Fe2+ formation. Therefore, P recovery as vivianite from WAS fermentation might be a promising and highly valuable approach to relieve the P crisis. [ABSTRACT FROM AUTHOR]

[Display omitted] • Monodispersed Co-N 3 sites on carbon nitride are constructed by in-situ reduction. • The k obs of trace urea degradation reaches 0.4576 min−1 under natural pH. • 1O 2 orients the urea degradation via the PMS activation on Co-N 3 sites. • Efficient trace urea removal is realized in modified ultrapure water production. The removal of trace urea presents a significant challenge in the production of electronic-grade ultra-pure water (UPW). This study proposed a simple strategy to regulate the low-coordination of a single-atom cobalt catalyst (R y Co-CN 0.20) for the efficient removal of trace urea via peroxymonosulfate (PMS) activation. The optimal R 0.50 Co-CN 0.20 with low-coordination Co-N 3 sites was constructed by in-situ reduction of NaBH 4 and significantly enhanced the PMS activation. The removal efficiency of trace urea achieved 94 % within 5 mins. The k obs of trace urea degradation in R 0.50 Co-CN 0.20 /PMS system reached 0.4576 min−1, which was much higher than previous reported systems. Experiments of free radical quenching and electron paramagnetic resonance demonstrated that singlet oxygen species were the dominant free radical. The corresponding steady concentration of singlet oxygen species in the R 0.50 Co-CN 0.20 /PMS system was enhanced to be 16.361 × 10–6 μM, which was twice of Co-CN 0.20 /PMS. Density functional theory calculations revealed that the optimized electron distribution of the Co center in the Co-N 3 sites processed a higher d band center (−1.08 eV) and richer electron transfer number (0.75 e−) compared with Co-N 4 sites, hence realizing the stronger PMS activation. Continuous operation verified that R 0.50 Co-CN 0.20 /PMS could maintain the removal rate of trace urea above 80 % after 150 h operation. Moreover, R 0.50 Co-CN 0.20 /PMS in the pilot UPW production process effectively reduced the pollution caused by trace urea and ensured the quality of the terminal UPW (Total organic carbon <1 μg/L). This study provides a new approach for the removal of trace urea through PMS activation by low-coordination single-atom catalysts. [ABSTRACT FROM AUTHOR]

The study explored an approach to improve the deep denitrification of tail water in denitrifying biofilter (DNBF) by utilizing alternative carbon sources withdrawn from the anaerobic fermentation of soybean wastewater due to its abundance and low costs. It was found in the batch tests that the alternative carbon sources could be obtained from soybean wastewater rapidly under optimal conditions. The obtained carbon sources were mainly consisted of acetic and propionic acids. The denitrification efficiency reached above 91% with the addition of fermented soybean liquids (FSL) with C/N ratio of 5 which was comparable to that of the commercial acetate. Further analysis demonstrated that the FSL was advantageous over the commercial acetate on the formation of biofilms and microbial diversity in DNBF which accounted for the satisfying performance of DNBF on the pollutants removal. Moreover, the potential environ-economic benefits could be expected by utilizing FSL as the alternative carbon source for deep denitrification which exhibited certain prospects in large-scale application. [ABSTRACT FROM AUTHOR]

The effects of magnetic biochar (MBC) on the anaerobic digestion efficiency of pigment sludge and the passivation of heavy metals Cd, Pb were investigated. MBC participated in the dual direct interspecies electron transfer effects of biochar and Fe 3 O 4 , improved the anaerobic digestion efficiency. Compared with the control group, the maximum volatile fatty acids (VFAs) concentration, the VS (volatile solids) removal rate, cumulative methane production, average daily methane production, and average daily methane production rate increased by 51.4 %, 37.8 %, 56.3 %, 56.3 %, 37.2 %, respectively. Moreover, MBC addition signally reduced the distribution rate of the bioavailable state of heavy metals in the pigment sludge and improved the passivation efficiency. Compared with the feedstock, the mass ratios of exchangeable and reducible Cr were reduced by 43.6 % and 61.6 %, and the corresponding ratios of Pb were reduced by 41.0 % and 59.2 %, respectively. The results indicate MBC could improve the efficiency of the anaerobic digestion of pigment sludge and reduce the bioavailability of heavy metals Cd and Pb. [Display omitted] • The iron content of MBC is significantly greater than BC. • MBC participate in the dual DIET effects of biochar and Fe 3 O 4. • The pigment sludge anaerobic digestion efficiency was enhanced by MBC. • MBC treatment can effectively immobilize the heavy metals by ion exchanging. • The bioavailability distribution rates were in an order of feedstock > A > B > C. [ABSTRACT FROM AUTHOR]

• Physicochemical interaction mechanisms between SMP and TMP were explored. • Fluorescence enhancement effect in the SMP-TMP interaction was elucidated. • Carboxyl, carbonyl and hydroxyl groups were mainly responsible for the interaction. • π-π and electrostatic interactions were involved in the SMP-TMP binding. Soluble microbial products (SMPs), dissolved organic matter excreted by activated sludge, can interact with antibiotics in wastewater and natural water bodies. Interactions between SMPs and antibiotics can influence antibiotic migration, transformation, and toxicity but the mechanisms involved in such interactions are not fully understood. In this study, integrated spectroscopy approaches were used to investigate the mechanisms involved in interactions between SMPs and a representative antibiotic, trimethoprim (TMP), which has a low biodegradation rate and has been detected in wastewater. The results of liquid chromatography-organic carbon detection-organic nitrogen detection indicated that the SMPs used in the study contained 15% biopolymers and 28% humic-like substances (based on the total dissolved organic carbon concentration) so would have contained sites that could interact with TMP. A linear relationship of fluorescent intensities of tryptophan protein-like substances in SMP was observed (R 2>0.99), indicating that the fluorescence enhancement between SMP and TMP occurred. Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy indicated that carboxyl, carbonyl, and hydroxyl groups were the main functional groups involved in the interactions. The electrostatic and π-π interactions were discovered by the UV-vis spectra and 1H nuclear magnetic resonance spectra. Structural representations of the interactions between representative SMP subcomponents and TMP were calculated using density functional theory, and the results confirmed the conclusions drawn from the 1H nuclear magnetic resonance spectra. The results help characterize SMP–TMP complexes and will help understand antibiotic transformations in wastewater treatment plants and aquatic environments. [Display omitted]. [ABSTRACT FROM AUTHOR]

Constructed wetland-microbial fuel cell (CW-MFC) is a novel technology for wastewater treatment with electrical generation. This work proposed a Fe–C micro-electrolysis substrate (Fe–C) with biomass modified ceramsite to enhance pollutants removal and electricity generation. The key influencing factors were revealed, and the COD, NH 4 +-N, and TP removal efficiency was respectively increased by 10.2, 8.1 and 8.78% with 76% higher power output at optimal conditions (e.g. OLR 52.5 g/(m2.d), HRT 48 h, and aeration rate 800 mL/min). Fe–C based substrates improved the microenvironments in CW-MFC, including dissolved oxygen (DO) and oxidation-reduction potential (ORP) lowering and electron transfer facilitation. These contributed to the enrichment of critical microorganisms and metabolic activities. The abundance of functional bacteria (i.e. Geobacter , Thauera and Dechloromonas) were evidently increased. Additionally, the energy metabolism and other functional genes encoding cytochrome c (ccoN), nitrite reductase (nirD) and phosphate transporter (pstA) were all stimulated. [Display omitted] • Fe–C along with self-developed BMC were applied to the CW-MFC. • Pollutant removal and power generation performance were significantly improved. • Microorganisms were enriched by Fe–C, especial for Geobacter , Thauera etc. • Energy metabolism and other functional genes (ccoN, nirD, and pstA) were stimulated. • The synergism among different particles in the CW-MFC system was discussed. [ABSTRACT FROM AUTHOR]

Two-stage aerobic coupled process consisted of anoxic, aerobic-1 with low DO and aerobic-2 with high DO (short for “A-LO-HO” process), was applied for post-treatment of poultry manure wastewater, which suffered by high ammonia nitrogen and high salinity. Outstanding NH 4 + -N removal efficiency of 99.5% was obtained, and the COD removal efficiency was about 75%, even under the severe stress. Multiple molecular technologies, include DGGE, real time PCR and high-throughput sequencing were applied to reveal the microbial community of the sludge. The reasonable distribution of the dominant bacteria Nitrosomonas and Nitrobacter would explain the synergistic effect of the partial nitrification in “A-LO” section and the completed nitrification in “HO” section. The microbial community and EPS analysis further confirmed the outstanding nitrifying ability, good salt-tolerant ability, and unaffected sedimentation property of the sludge with particular enhanced features which is acclimated for long time by the targeted coupled process and suitable for this kind of wastewater treatment. [ABSTRACT FROM AUTHOR]

• Allicin affected the VFAs generation and composition during WAS fermentation. • Allicin improved the particular fermentation processes for VFAs generation. • Allicin enhanced gene expressions involved in carbohydrate and amino acid metabolism. • Allicin enhanced environmental adaptation of microbes. • The core microbial community and encoding functional genes for VFAs were disclosed. As a frequently used product with antimicrobial activity, consumed allicin might be discharged and concentrated in waste-activated sludge (WAS). However, the influence of allicin (as an exogenous pollutant) on WAS fermentation has not been clearly revealed. This study aimed to disclose the impacts of allicin on volatile fatty acid (VFA) generation during WAS fermentation. The results showed that the appropriate presence of allicin (10 mg/g TSS) significantly enhanced the VFA yield (1894 versus 575 mg COD/L in the control) with increased acetate proportion (24.3%). Further exploration found that allicin promoted WAS solubilization, hydrolysis and acidification simultaneously. Metagenomic analysis revealed that the key genes involved in extracellular hydrolysis metabolism (i.e., CAZymes), membrane transport (i.e., gtsA and ytfT), substrate metabolism (i.e., yhdR and pfkC) and fatty acid synthesis (i.e., accA and accD) were all highly expressed. Allicin also induced the bacteria to produce more signalling molecules and regulate cellular functions, thereby enhancing the microbial adaptive and regulatory capacity to the unfavourable environment. Moreover, the variations in fermentative microbes and their contributions to the upregulation of functional genes (i.e., ytfR, g ltL, INV, iolD and pflD) for VFA generation were disclosed. Overall, the simultaneous stimulation of functional microbial abundances and metabolic activities contributed to VFA production in allicin-conditioned reactors. [Display omitted] [ABSTRACT FROM AUTHOR]

• MIT caused initial lag but final promoting effect on the VFAs in WAS fermentation. • MIT disintegrated WAS and disturbed ecological interaction & microbial metabolism. • Functional microorganisms for VFA production and MIT-tolerance were domesticated. • The adaptive mechanisms of microbiome to MIT stress were unveiled. • Syntrophic interaction of acetogen and methanogen was disrupted with total methanogenic activity suppression. In the post-COVID-19 pandemic era, various antimicrobials have emerged and concentrated in waste-activated sludge (WAS), affecting the biological treatment of WAS. However, there is still a knowledge gap in the dynamic response and adaptive mechanism of anaerobic microbiome under exogenous antimicrobial stress. This study found that methylisothiazolinone (MIT, as a typic antimicrobial) caused an interesting lag effect on the volatile fatty acids (VFAs) promotion in the WAS anaerobic fermentation process. MIT was effective to disintegrate the extracellular polymeric substances (EPS), and those functional anaerobic microorganisms were easily exposed and negatively impacted by the MIT interference after the loss of protective barriers. Correspondingly, the ecological interactions and microbial metabolic functions related to VFA biosynthesis (e.g., pyruvate metabolism) were downregulated at the initial stage. The syntrophic consortia gradually adapted to the interference and attenuated the MIT stress by activating chemotaxis and resistance genes (e.g., excreting, binding, and inactivating). Due to the increased bioavailable substrates in the fermentation systems, the dominant microorganisms (i.e., Clostridium and Caloramator) with both VFAs production and MIT-tolerance functions have been domesticated. Moreover, MIT disrupted the syntrophic interaction between acetogens and methanogens and totally suppressed methanogens' metabolic activities. The VFA production derived from WAS anaerobic fermentation was therefore enhanced due to the interference of antimicrobial MIT stress. This work deciphered dynamic changes and adaptive evolution of anaerobic syntrophic consortia in response to antimicrobial stress and provided guidance on the evaluation and control of the ecological risks of exogenous pollutants in WAS treatment. [Display omitted] [ABSTRACT FROM AUTHOR]

The activation of peroxymonosulfate (PMS) has gained significant interest in the removal of organic pollutants. However, traditional methods usually suffer from drawbacks such as secondary contamination and high energy requirements. In this study, we propose a green and cost-effective approach utilizing calcium oxide (CaO) to activate PMS, aiming to construct a simple and reliable PMS based advanced oxidation processes (AOPs). The proposed CaO/PMS system achieved fast degradation of methylene blue (MB), where the degradation rate of CaO/PMS system (0.24 min−1) was nearly 2.67 times that of PMS alone (0.09 min−1). Under the optimized condition, CaO/PMS system exhibited remarkable durability against pH changes, co-exists ions or organic matters. Furthermore, singlet oxygen (1O 2) was identified as the dominant reactive oxygen species by electron paramagnetic resonance (EPR) and quenching tests. Accordingly, the degradation pathways of MB are proposed by combing the results of LC/MS analysis and density functional theory (DFT) calculations, and the predicted ecotoxicity of the generated byproducts evaluated by EOCSAR could provide systematic insights into the fates and environmental risks of MB. Overall, the study provides an eco-friendly and effective strategy for treating dyeing wastewater, which should shed light on the application of PMS based AOPs. [Display omitted] • CaO/PMS process was effective and applicable for MB removal. • The key factors affecting the MB degradation rate were distinguished. • 1O 2 was the main activate species for the degradation of MB. • The main intermediates and reaction pathways of MB were proposed. • The toxicity of MB's intermediates were evaluated. [ABSTRACT FROM AUTHOR]

[Display omitted] • BPANN and H 2 O AutoML are compared to predict N & P removal in multiple WWTPs. • BPANN model has the universality in predicting the concentrations of ETN and ETP. • The predictable analysis of H 2 O AutoML has wide applicability for multiple WWTPs. • The effects of key variables on the prediction results are quantitively identified. The effective control of total nitrogen (ETN) and total phosphorus (ETP) in effluent is challenging for wastewater treatment plants (WWTPs). In this work, automated machine learning (AutoML) (mean square error = 0.4200 ∼ 3.8245, R2 = 0.5699 ∼ 0.6219) and back propagation artificial neural network (BPANN) model (mean square error = 0.0012 ∼ 6.9067, R2 = 0.4326 ∼ 0.8908) were used to predict and analyze biological nutrients removal in full-scale WWTPs. Interestingly, BPANN model presented high prediction performance and general applicability for WWTPs with different biological treatment units. However, the AutoML candidate models were more interpretable, and the results showed that electricity carbon emission dominated the prediction. Meanwhile, increasing data volume and types of WWTP hardly affected the interpretable results, demonstrating its wide applicability. This study demonstrated the validity and the specific advantages of predicting ETN and ETP using H 2 O AutoML and BPANN model, which provided guidance on the prediction and improvement of biological nutrients removal in WWTPs. [ABSTRACT FROM AUTHOR]

The efficient disposal of municipal organic wastes in low-carbon strategies is urgent but faces critical challenges. Anaerobic digestion is effective to recover high-valued resources (i.e., methane) from organic wastes; however, conventional mono-anaerobic digestion is restrained by limited organics content and imbalanced nutrient composition. This work proposed crawfish shell wastes and waste activated sludge co-digestion for effective biogas production. Results demonstrated an increase of 249.5 % methane yield in co-digestion systems compared to waste activated sludge mono-digestion. The crawfish shell wastes introduced considerable organics, which enhanced the microbial utilization of proteinaceous substrates, and prompted solubilization, hydrolysis, acidification, and methanogenesis steps. The microbial consortia were reshaped with the enrichment of hydrolytic-acidogenic bacteria (i.e., Proteiniclasticum ruminis and Acetoanaerobium sticklandii) and functional methanogens (i.e., Metanobacterium sp. and Metanopirillum sp.). Also, the methanogenic metabolic networks were stimulated, especially hydrogenotrophic methanogenesis, which was mainly attributed to the favorable conditions (including organics, pH, ORP, and trace elements) induced by crawfish shell wastes. [Display omitted] • CSW recycling as co-digestion substrates contributed to methane promotion evidently. • CSW improved bioavailable substrates and rebuilt favorable environmental conditions. • The hydrolysis, acidification and methanogenesis steps were all enhanced. • CSW benefitted the enrichment of hydrogenotrophic methanogens especially. • CSW strengthened hydrogenotrophic methanogenic metabolic networks. [ABSTRACT FROM AUTHOR]

[Display omitted] • A MOF-derived strategy was applied to prepare material (FeCo/C) with M@C structure. • FeCo alloy nanoparticles were uniformly encapsulated within carbon layers. • Direct reduction of O 2 into ·OH was enabled on FeCo/C via ORR in 3e− pathway. • The performance of FeCo/C was enhanced under alkaline condition. • A surface-independent outer sphere electron transfer mechnism was involved. Oxygen reduction reaction via 3-electron pathway presents a promising approach for generating reactive oxygen species in heterogeneous electro-Fenton (H-EF) process. This approach overcomes the limitations posed by the slow accumulation of H 2 O 2 via 2- electron ORR and the inefficient activation of H 2 O 2 through Haber-Weiss cycle. In this study, bimetal alloy nanoparticles were encapsulated within carbon layers (FeCo/C) by a general MOF-derived strategy, resulting in an overall electron transfer number of 2.98 during the H-EF process. Under optimal modification conditions, the prepared FeCo/C exhibited exceptional performance in sulfamethoxazole removal. Furthermore, the performance was enhanced under alkaline conditions. The apparent rate constant increased from 0.02 to 0.03 min−1 as the pH value increased from 3 to 11. The mechanism underlying this alkalinity-enhanced activity was attributed to the involvement of a surface-independent outer sphere electron transfer component, which provides valuable insights into the potential application of the H-EF process for treating alkaline wastewater. [ABSTRACT FROM AUTHOR]

Effect on microbial fuel cells (MFCs) for decolorization of Congo red by Poly (aniline-1,8-diaminonaphthalene) (PANDAN) modification, current and electroactive biofilms (EABs) is investigated. With the synergism of the three factors: PANDAN modification, current and EABs (A2 reactor), the COD removal and decolorization rate significantly increase to 88% and 97%, as well as the Congo red is thoroughly degraded. The decolorization performance comparison and Redundancy analysis (RDA) results indicate that the EABs take more responsibility (contribute ~ 50%) for the decolorization, rather than the modification and current. Therefore, the effects and mechanism of PANDAN modification and current on EABs are further revealed by the Confocal Scanning Laser Microscopy (CSLM) and high-throughput sequencing analysis. The effects of current (anodic dynamical microenvironment), material adsorption, and electron transfer mediating act comprehensively on the thickness, viability, EPS and microbial community of the EABs, among which the relationship is discussed in depth by hierarchically comparison, with "independent and additional effects". It is demonstrated that the modification, current and EABs present the synergistic effect and promote each other in the performance of the decolorization MFC. Image 1 • Synergism of modification, current and EABs improved MFC's decolorization. • EABs played the most important role, with ~50% contribution to the decolorization. • Modification, current and EABs presented synergistic effect and promoted each other. • Factors as independent or additional led different performance and mechanisms. [ABSTRACT FROM AUTHOR]

[Display omitted] • Co 3 O 4 nanosheets were uniformly embedded with metallic Ni@C NPs. • The Co3+/2+ cycling on bulk Co 3 O 4 was significantly accelerated by Ni@C NPs. • The activity of modified Co 3 O 4 in EA-PMS was enhanced by Ni@C NPs. • Effects of Ni@C NPs were verified by electrochemical tests and DFT calculation. • Solid proofs on the promotive effect of flow-through configuration were obtained. Electro-assisted activation of peroxymonosulfate (EA-PMS) by transition metals oxides (TMOs) has been extensively studied for the removal of organic pollutants. Despite TMOs possess considerable activity and affinity to PMS, their poor bulk conductivity still limits the electron exchange during the TMδ/δ+1 redox cycle, especially the efficient reduction of TMδ+1 via cathodic process. In this study, carbon felt loaded with modified Co 3 O 4 nanosheets (Co@FCF) was fabricated and applied as the flow-through electrode of EA-PMS process, where the Co 3 O 4 nanosheets were embedded with numerous metallic Ni particles encapsulated within carbon layers (Ni@C). Driven by weak electric current, continuous electrons can be supplied to the bulk Co 3 O 4 from the electron-rich Ni@C nanoparticles, resulting in accelerated Co3+/Co2+ cycle, enhanced production of SO 4 ·− and improved energy utilization efficiency. Electrochemical tests along with density functional theory calculations indicate that the unique structure of Co@FCF played essential role in the enhanced performance. [ABSTRACT FROM AUTHOR]

[Display omitted] • MIT differentially intervenes the acidogenesis and methanogenesis steps with efficient VFAs production. • MIT effectively disintegrates WAS via hydrogen-bonding interaction with C = O and N-H groups in organics (especially proteins). • The abundance and activity of hydrolytic-acidifying bacteria are selectively improved. • MIT contributes to the uptake, hydrolysis, and metabolism of amino acids and concurrently VFAs biosynthesis. • The reproductive and metabolic abilities of methanogens are suppressed due to the negatively affected central dogma system. Anaerobic fermentation is a promising approach for sludge treatment, although it is frequently hindered by the tight structure of extracellular polymeric substances (EPS) and limited metabolic activities. This work firstly discovered that methylisothiazolinone (MIT, a commonly used antimicrobial agent in water treatment) effectively disintegrated the sludge structure and stimulated metabolic pathways, leading to efficient volatile fatty acids (VFAs) production. The presence of MIT (ranging from 10 to 40 mg/g TSS) contributed to the acidogenic process but strongly restrained the methanogenesis, and the distinct interfering effect is highly associated with the MIT dose. The VFAs accumulation reached a maximum of 1776.7 mg COD/L (5.2 times of control) but faced a complete inhibition of methanogenic activity at 40 mg/g TSS. Spectroscopic and molecular docking analysis revealed that MIT interacted with and disrupted the EPS (mainly proteins) structure by forming hydrogen bonds with N-H groups. This disruption facilitated the release of biodegradable organics, which served as fermentation substrates. Furthermore, the MIT-mediated improvement selectively enriched the hydrolytic-acidifying bacteria (i.e., Clostridium and Caloramator) and stimulated the associated metabolic functions, particularly in the uptake, hydrolysis, and metabolism of amino acids considering the high expressions of encoding genes (e.g., oppA, pepP, gdhA). However, methanogens' reproductive and metabolic abilities were suppressed due to their inefficient response and adaptation to MIT. This suppression was evident through downregulated genetic expressions involved in DNA replication and aminoacyl-tRNA synthesis. Consequently, a decline in methanogens abundance (e.g., Methanothrix, and Methanosarcina) and methanogenic activity occurred, impeding the consumption of VFAs. This work provided an innovative niche to promote resource recovery in the sludge anaerobic system and deciphered the underlying mechanisms at both biochemical interactive steps and microbial genetic traits. [ABSTRACT FROM AUTHOR]

[Display omitted] • Glycerol conversion and nitrite accumulation in PD process were investigated. • NTR increased to 99.7% by preserving enough endogenous carbon source in cells. • Amino acids, nucleotide and glutathione metabolism obviously changed in PD reaction. • ROS generated in glycerol degradation was closely related to nitrite accumulation. Glycerol has been proven as an effective carbon source for partial denitrification (PD), while the underlying mechanism of the nitrite accumulation remains unknown. In this study, the nitrite accumulation characteristics was firstly investigated by batch tests. Denitrifying bacteria exhibited high nitrate to nitrite ratio (NTR) (84.6%) and nitrite accumulation rate (NAR) (30.23 mg N h−1 gMLVSS−1) in a typical PD process with sufficient glycerol supply. But when glycerol was exhausted, denitrifying bacteria entered endogenous PD process driven by polyhydroxyalkanoates (PHA) and glycogen, and the NTR and NAR significantly decreased to 63.9% and 1.74 mg N h−1 gMLVSS−1, respectively. More analysis found that keeping the endogenous carbon source at a relatively high level before PD reaction could further improved the NTR up to 99.7%. Metabolomic analysis showed that most required amino acids were synthesized in nitrite accumulation phase with active RNA metabolism. While in the subsequent nitrite reduction phase with limited glycerol, microbes tended to synthesize those amino acids with lower energetic cost, and activities related to DNA metabolism was more active in this phase. Moreover, reactive oxygen species generated in the glycerol degradation were deduced to be the key factor that induced the efficient nitrite accumulation. This study provided a comprehensive insight into the mechanism of glycerol-driven PD process. [ABSTRACT FROM AUTHOR]

Due to the shortage of phosphorus resources and the limitations of existing phosphorus recovery methods, phosphorus recovery in the form of vivianite has attracted considerable attention with its natural ubiquity, easy accessibility and foreseeable economic value. This review systematically summarizes the chemistry of vivianite, including the characteristics, formation process and influencing factors of the material. Additionally, the potential of phosphorus recovery as vivianite from wastewater has also been comprehensively examined from the prospects of economic value and engineering feasibility. In general, this method is theoretically and practically feasible, and brings some extra benefits in WWTPs. However, the insufficient understanding on vivianite recovery in wastewater/sludge decelerate the development and exploration of such advanced approach. Further researches and cross-field supports would facilitate the improvement of this technique in the future. Image 1061 • Vivianite formation is a complex process and is influenced by various factors. • P recovery as vivianite contributes to the sustainable use of P with high value. • The potential to recover vivianite from wastewater in WWTPs is great. • More research is required for the efficient vivianite recovery from wastewater. [ABSTRACT FROM AUTHOR]

Graphic abstract Highlights • SCFAs production from FW was enhanced by about 6-folds at appropriate LAS level. • LAS improved the solubilization of macromolecule organics in FW effectively. • The microbial activities related with SCFAs generation were stimulated with LAS. • The abundance of acidogenic bacteria responsible for SCFAs production was enriched. • The genes related with substrates bioconversion for SCFAs were highly expressed. Abstract An efficient attempt to improve the anaerobic fermentation of food wastes (FW) via the reuse of linear alkylbenzene sulphonates (LAS)-enriched laundry wastewater was reported. The production of short-chain fatty acids (SCFAs) from FW was enhanced by approximate 6-folds with high proportions of butyric and valeric acids at appropriate LAS level. Mechanism investigations demonstrated that the solubilization of macromolecule organics in FW was effectively improved by surface tension reduction. The hydrolysis and acidification processes during FW fermentation were accelerated and enhanced with the stimulation of microbial activities (higher activities of hydrolases and ATP concentrations). Also, the abundances of anaerobic microorganisms responsible for SCFAs production were enriched. Metatranscriptomic analysis indicated that the encoding genes involved in the metabolism of fermentation substrates for SCFAs production were highly expressed in LAS-added reactors. It was the simultaneous increase of bioavailable substrates and metabolic activities that contribute to the efficient SCFAs production in LAS-added reactors. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • High quality SCFAs was produced efficiently via the fermentation of WV/WAS mixture. • The optimal condition for SCFAs yields was at pH 8, WV/WAS ratio 1:1 within 4 d. • The dewaterability of fermentation residues was also enhanced in WV/WAS mixture. • Abundant bioavailable substrate was the prerequisite for SCFAs promotion in WV/WAS. • Higher abundance and activity of acidogens were significant to SCFAs enhancement. Abstract In this study, the efficient recovery of high-quality short-chain fatty acids from wine vinasse and waste activated sludge mixtures was investigated. The highest accumulation of short-chain fatty acids reached 3502 mg chemical oxygen demand per litre with a proportion of 82.5% acetic and propionic acids in the reactor with a wine vinasse/waste activated sludge mixture under optimized fermentation conditions, while merely 236 and 618 mg chemical oxygen demand per litre was accumulated in the reactors with waste activated sludge and wine vinasse systems alone, respectively. The mechanisms of the exceptional short-chain fatty acids promotion were mainly attributed to the simultaneous increase of bioavailable substrates and the fermentative community. The general microbial activity, key enzymes responsible for short-chain fatty acids generation, and diversity and abundance of fermentative bacteria were all enhanced under optimum conditions, which resulted in the rapid hydrolysis and acidification of bioavailable substrates for short-chain fatty acids generation. Moreover, the dewaterability of fermentation residues was also enhanced due to the presence of wine vinasses as skeleton builders. [ABSTRACT FROM AUTHOR]

Abstract Artificial sweeteners (ASs) are used in countless application in daily life. ASs are newly recognized as pollutants due to their high detection frequency in various environmental media, which has aroused great concern. This review presents the current knowledge of AS ecotoxicity and possible elimination routes in the environment. The obtained results indicate that the negative impacts of ASs are more severe than previously expected. More attention should be paid to the chronic and metabolite toxicities of ASs. Moreover, numerous processes (physical, chemical and biological) have been reported to be able to degrade ASs. However, the elimination efficiency varies greatly depending on the specific AS and the particular experimental conditions. Cyclamate and saccharin are easily removed, while sucralose and acesulfame are generally persistent. Additionally, there is a large gap in the ASs removal efficiency between bench tests and full-scale studies. The potential for microbial degradation of persistent ASs was reported in some regions, but clarification of the underlying mechanisms is necessary to increase the likelihood of using this approach in wide applications with a satisfactory performance. Graphical abstract Unlabelled Image Highlights • The ecotoxicity of ASs may be more severe than expected, especially SUC and ACE. • Numerous strategies have been proposed to eliminate the ASs. • SAC and CYC were easily removed but SUC and ACE were persistent in various mediums. • Efficient ACE biodegradation was reported in soil and WWTP with optimal condition. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Fe/PS treatment remarkably enhanced the VFAs production, especially acetic acid. • Sufficient bioavailable substrates were provided for acidification by Fe/PS. • High abundance and activity of fermentative bacteria were found in PS/Fe reactor. • The fermentation conditions were improved by the regulation of Fe in PS/Fe reactor. Abstract Evident synergistic effects of iron activated persulfate (Fe/PS) on the marked promotion of volatile fatty acids (VFAs) from waste activated sludge during anaerobic fermentation were reported. The maximal VFAs concentration was up to 2255 mg COD/L with the proportion of 72.8% acetic acid in the Fe/PS reactor while it was merely 120 and 517 mg COD/L in Fe and PS reactors, respectively. Fe/PS treatment could substantially improve the solubilization and hydrolysis processes via the combined chemical and biologic effects to provide sufficient bioavailable substrates for acidogenic bacteria. Meanwhile, the presence of Fe in Fe/PS reactors could alleviate the adverse effects of PS on environmental factors (i.e. ORP and pH) and simultaneously involve in the regulation of microbial growth and activities. The fermentative bacteria responsible for VFAs production were highly enriched and the activities of key acid-forming enzymes and ATP concentration were greatly improved in Fe/PS reactors. It was the overall improvement of bioavailable substrates, abundance and activities of acidogenic bacteria, and fermentation conditions that led to the high VFAs accumulation in Fe/PS reactors. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Efficient SCFAs production was accomplished by the fermentation of LW/WAS mixture. • The optimal fermentation condition was pH 8 with the LW/WAS ratio of 1:1 at 4 d. • Sufficient bioavailable substrates were provided for SCFAs production in LW/WAS. • The SCFAs promotion was stimulated by the C/N improvement and humic acid in LW/WAS. • High abundance and activity of fermentative bacteria were found in LW/WAS reactor. Abstract An efficient approach of bioconverting the organic wastes in liquor wastewater (LW) and waste activated sludge (WAS) to valuable short-chain fatty acids (SCFAs) via anaerobic fermentation was explored. The maximal SCFAs concentration was 5400 mg COD/L with approximate 80.0% acetic and propionic acids under optimized conditions (LW/WAS ratio 1:1, pH 8 and fermentation 4 d). Mechanisms investigation found that the fermentation of LW/WAS made up the drawbacks of sole WAS fermentation by improving the bioavailable substrates and low C/N ratio to stimulate the microbial activities. The bioconversion efficiency of substrates for SCFAs generation was therefore enhanced. The humic acids present in LW could also play positive roles in SCFAs promotion. Moreover, the performance of LW/WAS fermentation was highly correlated with appropriate fermentation pH. The fermentative bacteria responsible for SCFAs production were highly enriched and the activities of key hydrolases, acid-forming enzymes and ATP concentration were greatly improved at pH 8. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • PS/Fe treatment remarkably enhanced the SCFAs production, especially acetic acid. • PS/Fe accelerated the hydrolysis and acidification but inhibited methanogenesis. • The fermentative microbes producing SCFAs were highly enriched in PS/Fe reactor. • The quality of fermentation residue was greatly improved using PS/Fe treatment. Abstract This study reported a novel and efficient approach to improve the anaerobic fermentation performance of waste activated sludge (WAS) by the indigenous iron activated persulfate (PS/Fe) treatment. Firstly, the production of short-chain fatty acids (SCFAs), especially acetic acid, was remarkably enhanced within shorter fermentation time. Mechanism investigations demonstrated that the PS/Fe treatment could simultaneously accelerate and enhance the hydrolysis and acidification process while inhibit the methanogenesis during WAS fermentation. The activities of key enzymes and the abundances of anaerobic microorganisms responsible for SCFAs production were stimulated in the presence of PS/Fe which would promote the biological processes. Secondly, the PS/Fe treatment improved the quality of fermentation residue by reducing the toxic organic compounds in the residue and enhancing the dewaterability of fermented sludge, which was beneficial to the final disposal of WAS with added economical and environmental values. [ABSTRACT FROM AUTHOR]

• ZPT occurred in WAS facilitated the VFAs production during anaerobic digestion. • The particular impacts of ZPT on the main steps for VFAs yield were distinguished. • ZPT enriched functional species and improved microbial metabolic traits for VFAs. • ZPT contributed more prominently to the proteins metabolism for VFAs biosynthesis. • The microbial adaptation (QS and TCSs regulation) to ZPT toxicity was unveiled. The massive use of zinc pyrithione (ZPT, as broad-spectrum bactericides) resulted in its high levels in waste activated sludge (WAS) and affected subsequent WAS treatment. This work revealed the effects of ZPT on the volatile fatty acids (VFAs) during WAS anaerobic digestion, in which VFAs yield was enhanced by approximately 6-9 folds (from 353 mg COD/L in control to 2526-3318 mg COD/L with low level of ZPT (20-50 mg/g TSS)). The ZPT occurred in WAS enabled the acceleration of solubilization, hydrolysis and acidification processes while inhibited the methanogenesis. Also, the low ZPT contributed to the enrichment of functional hydrolytic-acidifying microorganisms (e.g., Ottowia and Acinetobacter) but caused the reduction of methanogens (e.g., Methanomassiliicoccus and Methanothrix). Meta-transcriptomic analysis demonstrated that the critical genes relevant to extracellular hydrolysis (i.e. CLPP and ZapA), membrane transport (i.e. gltI , and gltL), substrates metabolisms (i.e. fadj , and acd), and VFAs biosynthesis (i.e. porB and porD) were all upregulated by 25.1-701.3% with low level of ZPT. Specifically, the ZPT stimulus on amino acids metabolism for VFAs transformation was prominent over carbohydrates. Moreover, the functional species enabled to regulate the genes in QS and TCS systems to maintain favorable cell chemotaxis to adapt the ZPT stress. The cationic antimicrobial peptide resistance pathway was upregulated to blunt ZPT with the secretion of more lipopolysaccharide and activate proton pumps to maintain ions homeostasis to antagonize the ZPT toxicity for high microbial activities, the abundance of related genes was up-regulated by 60.5 to 524.5%. This work enlightened environmental behaviors of emerging pollutants on WAS anaerobic digestion process with interrelations of microbial metabolic regulation and adaptive responses. [Display omitted] [ABSTRACT FROM AUTHOR]

The catalyst of CuO x /granular activated carbon (GAC) was prepared and used as a heterogeneous Fenton-like catalyst for degradation of phenol in the microwave (MW)-induced H 2 O 2 catalytic oxidation process. The prepared catalysts were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS), X-ray diffraction (XRD), and N 2 adsorption–desorption techniques. Results showed that CuO and Cu 2 O were loaded on the surface of GAC. Effects of catalyst dosage, H 2 O 2 dosage, pH, MW power, and MW irradiation time on the degradation efficiency were studied. The phenol degradation efficiency reached 99.96%, corresponding to 88.6% chemical oxygen demand (COD) removal under optimal conditions with MW power of 400 W, CuO x /GAC dosage of 3 g/L, H 2 O 2 dosage of 2 mL/L, reaction time 4 min, and pH 4. The combined method of MW/catalyst/H 2 O 2 has been proven to be much more effective toward phenol degradation than using MW alone, catalyst alone, MW/catalyst, MW/H 2 O 2 , and catalyst/H 2 O 2 methods. In the presence of CuO x /GAC catalyst, the mechanism of phenol degradation under MW irradiation combined with H 2 O 2 was suggested. A synergistic effect of catalyst, MW, and H 2 O 2 contributes to the high degradation efficiency of phenol. The obtained kinetic equation for MW catalytic oxidation degradation of phenol was in line with first-order kinetic model. [ABSTRACT FROM AUTHOR]

A denitrifying microbial fuel cell (MFC) based on CO 2 regulation and Fe–C/biochar compound substrate supplementation was constructed to investigate the MFC performance, CO 2 fixation and microbial mechanism under different experimental conditions. The results showed that the addition of CO 2 and Fe–C/biochar compound substrate improved the electricity generation (397.8 mV, 88.3 mW/m2), denitrification rate and organic carbon removal performance (93.5%) of the system by promoting the generation of soluble microbial products (SMP), extracellular polymeric substances (EPS), volatile fatty acids (VFAs), polyhydroxyalkanoate (PHA) and glycogen in the cathode reactors. Microbial community analysis and metagenomic results revealed that both CO 2 and Fe–C/biochar compound substrates constitute a degree of positive feedback to denitrification and carbon fixation. Nevertheless, there were a large number of exoelectrogenic bacteria (Geobacter) attached to the biochar which merely had positive correlation with heterotrophic denitrifiers (Sulfurimonas and Methylophilus). Thermomonas and Thiobacillus were positively correlated with carbon felt rather than Fe–C. [Display omitted] • MFC mediated simultaneous denitrification and carbon fixation is feasible. • Fe–C/biochar compound substrate facilitates CO 2 electrosynthesis and denitrification. • The electrosynthesis of SMP, EPS, VFAs, PHA and glycogen are realized in MFC. • CO 2 fixation bacterium assist heterotrophic denitrifiers with denitrification. • Fe (II)-dependent denitrifiers show negative correlation with Fe–C. [ABSTRACT FROM AUTHOR]