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• PNAID achieved 82.2 % TN and 74.1 % TP removal at 12 °C. • PNA only achieved 53.9 % TN and 10.6 % TP removal. • Nitrate reduction is driven by heterotrophic and iron-based autotrophic denitrification. • Iron oxides act as a carrier ensuring the compact granular structure. • Improved intracellular iron stimulates microbial metabolic and energy conversion. Partial nitritation-anammox (PN/A), an energy-neutral process, is widely employed in the treatment of nitrogen-rich wastewater. However, the intrinsic nitrate accumulation limits the total nitrogen (TN) removal, and the practical application of PN/A continues to face a significant challenge at low temperatures (<15 °C). Here, an integrated partial nitritation-anammox and iron-based denitrification (PNAID) system was developed to address the concern. Two up-flow bioreactors were set up and operated for 400 days, with one as the control group and the other as the experiment group with the addition of Fe0. In comparison to the control group, the experiment group with the Fe0 supplement showed better nitrogen removal during the entire course of the experiment at different temperature levels. Specifically, the TN removal efficiency of the control group decreased from 82.9 % to 53.9 % when the temperature decreased from 30 to 12 °C, while in stark contrast, the experiment group consistently achieved 80 % of TN removal in the same condition. Apart from the enhanced nitrogen removal, the experiment group also exhibited better phosphorus removal (10.6 % versus 74.1 %) and organics removal (49.5 % versus 65.1 %). The enhanced and resilient nutrient removal performance of the proposed integrated process under low temperatures appeared to be attributed to the compact structure of granules and the increased microbial metabolism with Fe0 supplement, elucidated by a comprehensive analysis including microbial-specific activity, apparent activation energy, characteristics of granular sludge, and metagenomic sequencing. These results clearly confirmed that Fe0 supplement not only improved nitrogen removal of PN/A process, but also conferred a certain degree of robustness to the system in the face of temperature fluctuations. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • C. kluyveri bioaugmentation is proposed to enhance caproic acid fermentation. • Caproic acid concentration and selectivity reached 12.89 g/L and 55.08 %. • Microbial community structure was shifted by bioaugmentation. • Bacteria involved in degrading straw and producing caproic acid were enriched. Producing caproic acid via carboxylate platform is an environmentally-friendly approach for treating lignocellulosic agricultural waste. However, its implementation is still challenged by low product yields and selectivity. A microbiome named cellulolytic acid-producing microbiome (DCB), proficient in producing cellulolytic acid, was successfully acquired and shows promise for producing high-level caproic acid. In this study, a bioaugmentation method utilizing Clostridium kluyveri is proposed to enhance caproic acid yield of DCB using rice straw. With exogenous ethanol, bioaugmentation with Clostridium kluyveri significantly improved the caproic acid concentration and selectivity by 7 times and 4.5 times, achieving 12.9 g/L and 55.1 %, respectively. The addition of Clostridium kluyveri introduced reverse β-oxidation pathway, a more efficient caproic acid production pathway. Meanwhile, bioaugmentation enriched the bacteria proficient in degrading straw and producing short-chain fatty acids, providing more substrates for caproic acid production. This study provides potential bioaugmentation strategies for optimizing caproic acid yield from lignocellulosic biomass. [ABSTRACT FROM AUTHOR]

Recovery of bioenergy (CH 4) from agricultural waste is often limited by low hydrolysis rate due to its inherent recalcitrance structure. This study reports and demonstrates a new pretreatment strategy to enhance methane production from rice straw (RS). This is achieved by adding a commonly-used chemical, ferric chloride (FeCl 3), into RS, followed with 24 h of mixing under mesothermal condition (32 °C). The results showed that the addition of FeCl 3 ranging from 1.5 to 12.3 mmol/L effectively destroyed the inherent recalcitrance structure of RS and released more reducing sugar by shaping the chemical composition of the RS and reducing crystallinity index of cellulose. Biochemical methane potential (BMP) tests demonstrated that the pretreated RS at 3.1 mmol FeCl 3 /L increased the methane production from 10.3 ± 0.2 (i.e. control) to 18.3 ± 0.3 mol CH 4 /kg VS, indicating a relative increase by 78%. Comprehensive mechanism analyses suggested that the FeCl 3 pretreatment improved carbohydrates hydrolysis and stimulated the activity of methanogens during anaerobic digestion. Consequently, the methane yield was significantly increased with decreased lag-phase time in BMP tests, as revealed by the Modified Gompertz model. This study illustrated a cost-effective method of mesothermal FeCl 3 -based pretreatment to improve methane production from RS. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Fate of antibiotic resistance in iron-mediated process is evaluated. • ZVI supplement enhances the removal of antibiotics (from 55.6 ± 6.1 % to 89.8 ± 4.5 %) • The additional ZVI improved ARB, ARGs and MGEs removal efficiency. • ZVI supplement increased enzymes activity and enhanced biodegradation ability. • ZVI supplement modified microbial community and decreased potential hosts of ARGs. This study introduces zero-valent iron (ZVI) to enhance the removal of antibiotic resistance in piggery wastewater. Two integrated anoxic-aerobic biofilm reactors (IAOBRs) were operated simultaneously for 120 days, with one serving as a control reactor and the other as experimental reactor supplemented with ZVI. The experimental reactor demonstrated superior antibiotic removal efficiencies (89.8 ± 4.5 %), eliminating 99.7 ± 0.7 % of sulfonamides, 91.6 ± 4.5 % of tetracyclines and 81.1 ± 8.4 % of quinolones. The antibiotic resistance bacteria, antibiotic resistance genes (ARGs) and mobile genetic elements removal efficiency reached 0.69–1.74, 2.06 and 2.15 logs, respectively. In comparison to the control reactor, the activated sludge in the experimental reactor also experienced a reduction in total antibiotic concentrations by 57.58 ± 19.99 %. The enhanced performance of the iron-mediated process in antibiotic resistance removal is attributed to the augmentation of enzymatic activity, biodegradation ability, and enrichment of specific microorganisms. The introduction of ZVI also modified the microbial community composition and decreased the potential hosts of ARGs. The proposed iron-mediated process greatly enhances antibiotic resistance removal from wastewater and mitigates antibiotic accumulation in activated sludge, offering new insights into wastewater biological treatment for eliminating antibiotic resistance. [ABSTRACT FROM AUTHOR]

A staged butyrate-butanol fermentation process (SBBFP) has been developed to efficiently produce biobutanol from renewable lignocellulose. The SBBFP combines the fermentation of bioaugmented degradation consortium for butyrate (BDCB) and butanol production of Clostridium beijerinckii , but is still challenged by the lower specific butanol yield (SBY). In this study, a novel technology for synthesizing semiconductor nanoparticles (NPs) and their self-assembly with Clostridium beijerinckii was proposed to enhance the SBY. Results showed that supplement of 0.1 g/L CuSO 4 or 0.2 g/L ZnSO 4 were more favorable for the formation of butyrate and NPs (CuS/Cu 2 S or ZnS) in the acidogenic fermentation process of BDCB. Butyrate production achieved 19–21 g/L in the fed-batch fermentation mode from NaOH-pretreated rice straw. Only CuS/Cu 2 S can be assembled with NPs@ C. beijerinckii hybrid system, and a butanol production of 14.6 g/L was obtained using acidogenic fermentation broth and saccharide liquid from rice straw as the co-substrates, with the SBY of 0.17 g/g initial pretreated rice straw. The enhanced butanol synthesis was likely attributed to the upgraded intracellular NADH/NAD+ and specific activity of enzyme CoA-transferase (ctf AB) in C. beijerinckii. The research work provides an efficient approach for biofuels and biochemical production from lignocellulose, along with the extended application of biological nanotechnology. [ABSTRACT FROM AUTHOR]

[Display omitted] • The microbiological mechanism of antibiotic removal in SBR-UMSR is investigated. • Heterotrophs-induced metabolism plays a crucial role in antibiotic biodegradation. • AOB-induced co-metabolism has minor contributions to antibiotic biodegradation. • Redox, transfer and hydrolysis are key chemical strategies for antibiotic removal. A process integrating the sequencing batch reactor (SBR) and up-flow microaerobic sludge reactor (UMSR) has been innovatively developed to effectively remove antibiotics from manure-free piggery wastewater. This study provides a comprehensive analysis of bacteria, genes, and enzymes crucial for antibiotic biodegradation to reveal the underlying microbiological mechanism of antibiotic removal. During the 230-day operational period, a significant succession of microbial communities was observed in the SBR-UMSR system. Intriguingly, microbial interactions were pivotal in dominating the community succession, accounting for a substantial contribution of 69.12%, while abiotic factors only accounted for 30.88%. The analysis of the microbial community and network revealed that the predominant mechanism for antibiotic biodegradation in the SBR-UMSR system was driven by the metabolic activities of heterotrophic bacteria. More denitrifying bacteria were involved in antibiotic biodegradation than ammonia-oxidizing bacteria. In SBR, most of the potential antibiotic-degrading bacteria (PADB) were Gram-positive and facultatively anaerobic, whereas in UMSR, they were Gram-negative and aerobic. Propioniciclava and Norank_f__AKYH767 were the dominant PADB in the SBR and UMSR, respectively. Network analysis pinpointed redox reactions, transfer processes, and hydrolysis reactions as the core processes facilitating antibiotic biodegradation. Despite a general decrease in the abundance of most antibiotic resistance genes (ARGs) in the activated sludge of both SBR and UMSR over the 230-day operation, there was a notable enrichment in multidrug resistance genes. This underlines the necessity for proper sludge management to prevent secondary contamination by ARGs. This research provides deep insights into the mechanisms of antibiotic removal in intricate microbial ecosystems. [ABSTRACT FROM AUTHOR]

A lab‐scale hybrid anoxic‐oxic biofilm reactor (HAOBR) with one anoxic compartment and two oxic compartments in sequence was constructed to treat domestic wastewater in this study. Performance of the HAOBR was evaluated at 25°C and hydraulic retention time 12 hr with reflux ratio increased from 100% to 300% by stages. The results showed that COD, NH4+‐N, and TN removal presented an increasing trend with the increase of reflux ratio by stages. At the optimal reflux ratio of 300%, removal of COD, NH4+‐N, and TN averaged 83.9%, 99.0%, and 80.8%, respectively. Analysis about pollutant concentration in each compartment of the HAOBR revealed that the excellent pollutant removal was mainly achieved by the cooperation of nitrification in 3rd oxic compartment and denitrification in 1st anoxic compartment. Denitrification in the anoxic zone of 2nd oxic compartment would also contribute to the nitrogen removal. The higher nitrogen removal of the HAOBR at the reflux ratio of 300% is attributed to the presence of the anammox in the 1st anoxic compartment, which is mainly due to the lower COD concentration in the compartment at the higher reflux ratio. Practitioner points: A hybrid anoxic‐oxic baffled reactor was built to treat domestic wastewater.Effect of reflux ratio and mechanism of nitrogen removal were investigated.Reflux ratio 300% was favorable for COD, NH4+ and TN removal.The removal of COD, NH4+ and TN averaged 84.4%, 99.0% and 80.8%, respectively.Cooperation of nitrification, denitrification and anammox dominated the high nitrogen removal at the higher reflux ratio of 300%. [ABSTRACT FROM AUTHOR]

Flexible capacitive pressure sensors play a crucial role in wearable electronics and robotics. However, their susceptibility to environmental noise poses challenges to sensing precision. To mitigate the impact of environmental influences, a sensor capable of producing signals orders of magnitudes larger than the noise becomes essential. One straightforward method to enhance capacitance values involves reducing the thickness of the dielectric layer. Yet, when this reduction reaches nanometer scale, the dielectric layer may become mechanically vulnerable and more importantly, their charge storage capability is compromised due to electron tunneling. To address these challenges, here the naturally formed alumina (Al2O3) on aluminum (Al) surface is employed as a stable and ultra‐thin dielectric layer. Simultaneously, the Schottky effect at the Al‐Al2O3‐carbon black (CB) interface is harnessed to prevent electron tunneling. These strategies collectively yielded a large unit‐area capacitance (UAC) of 50 nF cm−2 and demonstrated high electrical and environmental stability. Furthermore, hollow hemispherical microstructures are incorporated at the interface, resulting in a flexible pressure sensor with high sensitivity (8.6 kPa−1) and a linear response up to 50 kPa. With its simple two‐layer structure, this sensor can be seamlessly integrated in situ and offers commercial‐grade resolution at mN‐level for monitoring human biomechanical signals. [ABSTRACT FROM AUTHOR]

IWA Anaerobic Digestion Model No. 1 (ADM1) is the most widely recognised and popular mathematical model for anaerobic digestion processes. However, the application of ADM1 to acidogenic fermentation is limited by its use of constant stoichiometry to describe the formation of products via carbohydrate fermentation. This study presents a modification of ADM1 using a variable acidogenic stoichiometric approach in which the hydrogen partial pressure (p H2) and pH are used to predict and regulate the acidogenic process. The fermentation of ethanol and its kinetics were introduced into the model structure. Experimental data from mixed acid-type fermentation in a 28.4 L anaerobic baffled reactor (ABR) fed with a sucrose solution with a chemical oxygen demand of 4000 mg L−1 were used to calibrate the model parameters. Two case studies involving continuous ethanol-type fermentation in an ABR and a continuous stirring tank reactor (CSTR) were used to validate the approach. The modified model achieved good predictions of the experimental data collected from butyric acid, propionic acid, mixed acid, and ethanol-type fermentation in the ABR and CSTR using the standard ADM1 parameter values without any parameter fitting beyond implementation of the variable acidogenic stoichiometry. The p H2 and pH thresholds in butyric acid, propionic acid, mixed acid, and ethanol-type fermentation could be predicted using this model, which was shown to be a valid mathematical tool for the regulation of fermentation type. Image 1 • ADM1 is modified by using variable acidogenic stoichiometry, derived from H 2 and pH. • Ethanol fermentation and its kinetics are introduced to model structure. • Variable acidogenic stoichiometry has been calibrated and validated. • Thresholds of p H2 and pH in acidogenic fermentation are predicted by this model. [ABSTRACT FROM AUTHOR]

China produces more than 20 % of maize grain in the world, and Northeast China (NEC) accounts for ∼30 % of the nation's total maize production. Previous studies have used either climate data, satellite data, or crop growth model (CGM) to predict or forecast maize yield. However, maize is highly susceptible to the effect of extreme climate events (such as drought, heat) in NEC, and there is a lack of studies to predict/forecast maize yield by integrating climate data, satellite data, extreme climate events, and CGM-simulated data. We aim to develop a hybrid approach with machine learning to blend different sources of data (climate data, satellite data, extreme climate events) and process-based modelling results to improve predictive accuracy of maize yield in NEC. Using maize data from 44 sites during the period of 2000–2013 in NEC, we firstly optimized Agricultural Production System sIMulator (APSIM) using Differential Evolution Adaptive Metropolis combined with Gaussian likelihood function and Bayesian multiplication method. Next, we divided the growing season into five phases, and selected variables of different phases using exploratory data analysis and Random Forest. Then, we developed a hybrid model using Random Forest by blending of multiple sources of data and APSIM simulations to predict maize yield from the start to the end of the growing season, and quantified the relative contribution of predictors. A hybrid model developed with random forest by combining climate data, NDVI, extreme climate events and APSIM simulations can achieve high performance for predicting yield toward the end of the growing season. The accuracy of in-season yield prediction showed a linear increase with MAPE/KGE changing from 19 %/0.05 to 13 %/0.53 from start to end of the growing season. Yield forecasts are acceptable with RMSE/MAE of 1.20/1.01 Mg ha−1 (16 %/13 % of the observed mean yield) approximately one-month prior to harvest. The most important predictor that affect yield forecast was APSIM-simulated biomass or yield, and the most important extreme climate event was drought during early grain-filling stage. With the increasing availability of crop-related data, we expect that the in-season forecasting capacity of the proposed methodology could be further improved, and the methodology can be extended to other crops and other regions for yield forecast. [Display omitted] • A hybrid approach with biophysical modelling and machine learning developed to predict maize yield. • It integrates climate data, NDVI, extreme climate events, and APSIM-simulated biomass or yield. • It could be used for in-season yield prediction approximately one-month prior to harvest. • The most important predictor was APSIM-simulated biomass or yield. • The most important extreme climate event was drought during early grain-filling stage. [ABSTRACT FROM AUTHOR]

[Display omitted] • Co is added to improve the efficiency of two-phase anaerobic digestion. • The optimal Co2+ concentration is 2.0 mg/L to improve the activity of methanogens. • EDDS is the most effective for improving methanogenesis and Co bioavailability. • Co-EDDS accelerates the recovery of methanogenic phase from ammonium and pH shocks. • Co-EDDS increases VB 12 and coenzyme F 420 , and enriches methanogens. Two-phase anaerobic digestion (AD) is a promising technology, but its performance is sensitive to methanogen. In this study, the effect of cobalt (Co) on two-phase AD was investigated and the enhanced mechanism was revealed. Though no obvious effect of Co2+ was observed in acidogenic phase, the activity of methanogens was significantly affected by Co2+ with an optimal Co2+ concentration of 2.0 mg/L. Ethylenediamine-N'-disuccinic acid (EDDS) was the most effective for improving Co bioavailability and increasing methane production. The role of Co-EDDS in improving methanogenic phase was also verified by operating three reactors for two months. The Co-EDDS supplement increased the level of Vitamin B12 (VB 12) and coenzyme F 420 , and enriched Methanofollis and Methanosarcina , thereby successfully improving methane production and accelerating reactor recovery from ammonium and acid wastewater treatment. This study provides a promising approach to improve the efficiency and stability of anaerobic digester. [ABSTRACT FROM AUTHOR]

Highlights • Specific QS signals of various populations in anaerobic digestion were identified. • Most AHLs in anaerobic digestion were secreted in starvation conditions. • The specific QS signals induced the K -strategy of populations to survive. • The QS regulated cooperation among populations in resource-limited situations. • Profiles of AHLs indicated the performance of anaerobic digestion processes. Abstract A series of dominant functional floras involved in anaerobic digestion was obtained by subculturing anaerobic sludge with specific substrates, respectively, and their specific quorum sensing signals (AHLs) were identified. It was found that most of the AHLs were secreted in starvation of the functional floras. One or two AHLs were found to have a significant positive correlation with the behavior of hydrolytic-fermentative bacteria, homoacetogens, syntrophic propionate-oxidizing bacteria, syntrophic butyrate-oxidizing bacteria and aceticlastic methanogens, respectively. Hydrogenotrophic methanogens had a various self-organization means and broader relations with the other populations, which was induced by six AHLs at least. Performance of an upflow anaerobic sludge blanket in the startup process revealed that the dominant populations involved in anaerobic digestion would secret specific AHLs to induce K -strategy in resource-limited situation for reproduction and regulating their cooperation. This work presents a novel perspective on the social behaviors of microbial populations in anaerobic digestion. [ABSTRACT FROM AUTHOR]

Bicarbonate (HCO 3 − ) has been extensively researched as a buffer in anaerobic digestion. The effect of HCO 3 − concentration on syntrophic butyrate oxidation process was evaluated by batch culturing of anaerobic activated sludge, and the mechanism was further revealed by the changes of Gibbs free energy (Δ G ) and the interspecies transfers of electron and proton. The results showed that butyrate degradation rate was enhanced by 32.07% when the supplement of HCO 3 − increased from 0 to 0.20 mol/L. However, methane production and acetate degradation were strongly inhibited by HCO 3 − more than 0.10 mol/L. More function of HCO 3 − was found as 1) decreasing the Δ G of syntrophic methanogenesis of butyrate while increasing the Δ G of methanogenesis of acetate, 2) enriching M. harundinacea and M. concilii , 3) increasing the diffusion rate of protons between the syntrophic consortia. This work would increase the anaerobic digestion efficiency by enhancing the interaction of the syntrophic consortia. [ABSTRACT FROM AUTHOR]

One-pot bioconversion is an economically attractive biorefinery strategy to reduce enzyme consumption. Direct conversion of lignocellulosic biomass for butyric acid production is still challenging because of competition among microorganisms. In a consolidated hydrolysis/fermentation bioprocessing (CBP) the microbial structure may eventually prefer the production of caproic acid rather than butyric acid production. This paper presents a new bioaugmentation approach for high butyric acid production from rice straw. By dosing 0.03 g/L of Clostridium tyrobutyricum ATCC 25755 in the CBP, an increase of 226% higher butyric acid was yielded. The selectivity and concentration also increased to 60.7% and 18.05 g/L, respectively. DNA-sequencing confirmed the shift of bacterial community in the augmented CBP. Butyric acid producer was enriched in the bioaugmented bacterial community and the bacteria related to long chain acids production was degenerated. The findings may be useful in future research and process design to enhance productivity of desired bio-products. [ABSTRACT FROM AUTHOR]

Butyrate production from renewable biomass shows great potential against climate change and over-consumption of fossil fuels. Herein, key operational parameters of a cathodic electro-fermentation (CEF) process were optimized for efficient butyrate production from rice straw by mixed culture. The cathode potential, controlled pH and initial substrate dosage were optimized at −1.0 V (vs Ag/AgCl), 7.0 and 30 g/L, respectively. Under the optimal conditions, 12.50 g/L butyrate with yield of 0.51 g/g-rice straw were obtained in batch-operated CEF system. In fed-batch mode, butyrate production significantly increased to 19.66 g/L with the yield of 0.33 g/g-rice straw, but 45.99% butyrate selectivity still needs to be improved in future. Enriched butyrate producing bacteria (Clostridium cluster XIVa and IV) with proportion of 58.75% on the 21st day of the fed-batch fermentation, contributed to the high-level butyrate production. The study provides a promising approach for efficient butyrate production from lignocellulosic biomass. [Display omitted] • A CEF system is optimized for efficient butyrate production from rice straw. • The optimal cathode potential, pH and initial substrate are −1.0 V, 7.0 and 30 g/L. • Optimized batch CEF obtained 12.50 g/L butyrate with 0.51 g/g-rice straw yield. • 19.66 g/L butyrate is achieved by enriched functional bacteria in fed-batch CEF. [ABSTRACT FROM AUTHOR]

In this a, three-layered feedforward-backpropagation artificial neural network (BPANN) model was developed and employed to evaluate COD removal an upflow anaerobic sludge blanket (UASB) reactor treating industrial starch processing wastewater. At the end of UASB operation, microbial community characterization revealed satisfactory composition of microbes whereas morphology depicted rod-shaped archaea. pH, COD, NH 4 + , VFA, OLR and biogas yield were selected by principal component analysis and used as input variables. Whilst tangent sigmoid function ( tansig ) and linear function ( purelin ) were assigned as activation functions at the hidden-layer and output-layer, respectively, optimum BPANN architecture was achieved with Levenberg-Marquardt algorithm ( trainlm ) after eleven training algorithms had been tested. Based on performance indicators such the mean squared errors, fractional variance, index of agreement and coefficient of determination (R 2 ), the BPANN model demonstrated significant performance with R 2 reaching 87%. The study revealed that, control and optimization of an anaerobic digestion process with BPANN model was feasible. [ABSTRACT FROM AUTHOR]

A novel consolidated bioprocess for hyper-production of butyric acid from delignified rice straw without exogenous enzymes involved was developed by co-fermentation of Clostridium thermocellum ATCC 27405 and C. thermobutyricum ATCC 49875. Feasibility of the consolidated bioprocess was approved by batch fermentations, with the optimum pH of 6.5. Fed-batch fermentation with a constant pH of 6.5 at 55 °C could enhance the butyric acid yield to a remarkable 33.9 g/L with a selectivity as high as 78%. Metabolic analysis of the co-culture indicated that sugars liberated by C. thermocellum ATCC 27405 were effectively converted to butyric acid by C. thermobutyricum ATCC 49875. Secondary metabolism of C. thermobutyricum ATCC 49875 also contributed to the hyper-production of butyric acid, resulting in the re-assimilation of by-products such as acetic acid and ethanol. This work provides a more effective fermentation process for butyric acid production from lignocellulosic biomass for future applications. [ABSTRACT FROM AUTHOR]

Lignocellulosic biomass has been increasingly used for biofuel production, such as biohydrogen and biobutanol. However, the enzymes used in hydrolysis result in a large increase in production cost. To reduce the enzyme involvement in lignocellulosic butanol, a novel two-stage fermentation process was constructed by combining a Carboxylate Platform and acetone-butanol-ethanol (ABE) fermentation. First, without enzyme involvement, lignocellulose was converted to volatile fatty acids (VFAs) using the Carboxylate Platform. Subsequently, the VFAs were used as feedstock to generate butanol by ABE fermentation of Clostridium beijerinckii NCIMB 8052. Fed with 20 g/L pretreated rice straw, the acidogenic fermentation produced 660 mL/L hydrogen and 6.87 g/L butyric acid, with a total VFAs of 9.52 g/L in the supernatant of fermentation culture (SFC). With 40% rice straw hydrolysate and 60% SFC as co-substrate, hydrogen and butanol productions of 5897 mL/L and 13.8 g/L, respectively, were obtained in the ABE fermentation. Mass balance and energy generation analysis showed that the specific butanol and energy yields from rice straw reached 230 g/kg and 9633.7 kJ/kg, respectively. Additionally, the carbon-flow distribution analysis indicated that the SFC supplement decreased the metabolic flux of acetone producing pathway and increased the metabolic flux of butanol producing pathway. The novel two-stage fermentation process was a more effective approach for energy generation from lignocellulose that avoided external addition of commercial butyric acid and reduced enzyme involvement for fermentation product. [ABSTRACT FROM AUTHOR]

A novel upflow microaerobic sludge reactor (UMSR) was constructed to treat manure-free piggery wastewater with high NH 4 + -N and low COD/TN ratio. In the light of the potential effect of effluent reflux ratio (RR) on nitrogen removal, performance of the UMSR was evaluated at 35 °C and hydraulic retention time 8 h with RR decreased from 45 to 25 by stages. A COD, NH 4 + -N and TN removal of above 77.1%, 80.0% and 86.6%, respectively, was kept with a RR over 35. To get an effluent of TN not more than 80 mg/L with a TN load removal above 0.88 kg/(m 3 ·d), the RR should be at least 34. Real-time quantitative polymerase chain reaction of functional bacteria revealed that the RR of less than 34 stimulated ammonium oxidation but badly inhibited anammox, the dominant nitrogen removal pathway, resulting in the remarkable decrease of nitrogen removal in the reactor. [ABSTRACT FROM AUTHOR]

Herein, an upflow anaerobic sludge blanket reactor was employed to treat potato starch processing wastewater and the efficacy, kinetics, microbial diversity and morphology of sludge granules were investigated. When organic loading rate (OLR) ranging from 2.70 to 13.27 kg COD/m 3 .d was implemented with various hydraulic retention times (72 h, 48 h and 36 h), COD removal could reach 92.0–97.7%. Highest COD removal (97.7%) was noticed when OLR was 3.65 kg COD/m 3 .d, but had declined to 92.0% when OLR was elevated to 13.27 kg COD/m 3 .d. Methane and biogas production increased from 0.48 to 2.97 L/L.d and 0.90 to 4.28 L/L.d, respectively. Kinetics and predictions by modified-Gompertz model agreed better with experimental data as opposed to first-order kinetic model. Functional population with highest abundance was Chloroflexi (28.91%) followed by Euryarchaeota (22.13%), Firmicutes (16.7%), Proteobacteria (16.25%) and Bacteroidetes (7.73%). Compared with top sludge, tightly-bound extracellular polymeric substances was high within bottom and middle sludge. Morphology was predominantly Methanosaeta -like cells, Methanosarcina -like cells, rods and cocci colonies. [ABSTRACT FROM AUTHOR]

The effect(s) of zero-valent iron (ZVI) in anaerobic digestion and its related impact on microbial community structure is still unclear. The effect of addition of 0, 1, 4, 10, 20 g/L ZVI on the microbial community structure was investigated during methanation from potato starch processing wastewater (PSPW). Methane production rate constants ( k ) obtained from kinetics studies indicated ZVI dosage had impacted on the methanation and microbial community structure. 16S rRNA gene sequencing revealed Chloroflexi, Firmicutes, Euryarchaeota, Bacteroidetes, Proteobacteria, and Synergistetes as dominant phyla in all samples. When ZVI was employed, Chloroflexi, Firmicutes and Euryarchaeota increased by 2.46, 1 and 3.53 times, respectively, whereas Bacteroidetes, Synergistetes, Proteobacteria and Caldiserica decreased. Growth trend was similar for populations of the genus Methanosaeta , Levilinea , Longilinea and Syntrophomonas . Microbial community shift was most pronounced in assays with 10 and 20 g/L ZVl. ZVl dosed reactors performed better at methanation as opposed to non-ZVl dosed reactor and 10 g/L ZVl was the optimum dose. The study revealed that, ZVI had impacted positively on the microbial community structure to favor and enhance both hydrolysis-acidification and methanogenesis processes during PSPW digestion. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel MV-mediated CEF system is proposed for efficient butanol production. • Methyl viologen supplement inhibits H 2 formation and enhances butanol production. • Exogenous butyric acid enhances butanol production in the MV-mediated CEF system. • Butanol selectivity from co-substrates of glucose and butyric acid achieves 90.44%. Butanol production by solventogenic Clostridia shows great potential to combat the energy crisis, but is still challenged by low butanol selectivity and high downstream cost. In this study, a novel cathodic electro-fermentation (CEF) system mediated by methyl viologen (MV) was proposed and sequentially optimized to obtain highly selective butanol production. Under the optimal conditions (−0.60 V cathode potential, 0.50 mM MV, 30 g/L glucose), 7.17 ± 0.55 g/L butanol production were achieved with the yield of 0.32 ± 0.02 g/g. With the supplement of 4 g/L butyric acid as co-substrate, butanol production further improved to 13.14 ± 1.14 g/L with butanol yield and selectivity as high as 0.43 ± 0.01 g/g and 90.44 ± 1.66%, respectively. The polarized electrode enabled the unbalanced fermentation towards butanol formation and MV further inhibited hydrogen production, both of which contributed to the high-level butanol production and selectivity. The MV-mediated CEF system is a promising approach for cost-effective bio-butanol production. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel integrated process of anammox with Fe0 is developed. • High-level nutrient removal and treatment capacity are achieved in the process. • Fe0 enriches nitrate removal pathway and improves the activity of denitrifiers. • The chemical precipitation with Fe2+/Fe3+ enhances phosphorus removal. • Fe0 accelerates sludge granulation by stimulating the secretion of EPS and AHLs. This study aims to develop and demonstrate a novel integration of anammox with zero-valent iron (Fe0) for highly efficient wastewater treatment. The process enables not only enhanced phosphorus removal but also favored sludge granulation to reduce footprint, and more importantly, leads to a combination of microbial iron (Fe)-based denitrification for high-level nitrogen removal. In an integrated laboratory system, superior performances of nitrogen and phosphorus removal and treatment capacity were achieved over one year. With low-strength mainstream wastewater (NH 4 +-N = 58.2 ± 0.6 mg/L) as influent, total nitrogen (TN) removal efficiency stabilized at 97.4 ± 1.6 %, with effluent TN concentration of <2.0 mg N/L. Phosphorus removal was also high above 90 %, attributed to the formation of chemical precipitates in sludge granulation with a mean volume diameter of ∼1 mm. The formation of granular sludge was due to that the Fe0 served as carriers to support microbial attachment and growth, and stimulated the secretion of extracellular polymeric substances to accelerate microbial aggregation. A 16S rRNA gene sequencing analysis, together with a series of batch activity tests revealed that the added Fe0 enriched nitrate removal pathway and improved the activity of denitrifiers, thereby successfully polishing effluent with a very low TN level. Overall, this proposed integrated process is proved to be a promising technology of simultaneously achieving high-level nitrogen, phosphorus removal and capacity for next-generation wastewater treatment. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fate of antibiotics contained in MFPW is evaluated in a combined SBR-UMSR process. • 50.1% of the total antibiotics in the MFPW is eliminated by the combined process. • The SBR and UMSR contribute 18.9% & 31.1% to the removed antibiotics. • Biodegradation is the primary mechanism responsible for the antibiotic removal. • Antibiotic degradation is mainly achieved by metabolism, assisted by co-metabolism. Extensive use of antibiotics in pig farms presents chronic toxicity and induces antibiotic resistant genes in the natural environment. Tetracyclines (TCs), fluoroquinolones (FQs), and sulfonamides (SAs) are the widely detected antibiotics in manure-free piggery wastewater (MFPW) with the concentration of 4.92–164.60 μg/L. A novel combined sequencing batch reactor (SBR)-upflow microaerobic sludge reactor (UMSR) process has been demonstrated efficient in removing conventional pollutants from the MFPW. It is here shown that the SBR-UMSR process effectively removed 92.68 % of SAs and 82.23 % of TCs. The removal rate of FQs in the SBR-UMSR process was only 39.65 % due to the refractory properties. As a consequence, the total removal of antibiotics was 50.1 ± 32.5 % in the combined SBR-UMSR process, with the removal of 18.9 ± 36.6 % and 31.1 ± 24.3 % from the front-end SBR and back-end UMSR, respectively. Mass balance analysis proved that 54.18 % of antibiotics in the combined process were removed via biodegradation/biotransformation, and 12.75 % removal was achieved by sludge adsorption. Partial least-squares path model analysis and network analysis revealed that the biodegradation of antibiotics was mainly achieved by the metabolism of microorganisms with co-metabolism as a complement. The outcomes of this study provide valuable insights into the mechanism of antibiotic removal in biological processes. [ABSTRACT FROM AUTHOR]

[Display omitted] • A co-cultivation of yeasts is proposed for efficient single-cell protein production. • C. utilis , G. candidum and C. tropicalis (9:5:1) is the optimal yeast combination. • The optimal conditions are 12 % inoculation (v / v), 24℃, 200 rpm and natural pH. • The single-cell protein yield and COD removal are 3.06 g/L and 56.9 %, respectively. • A resource-recycling process of starch wastewater is proposed. Single-cell protein (SCP) from potato starch processing wastewater (PSPW) shows great potential against protein scarcity and unsustainable production of plant and animal proteins. In this study, five yeasts were selected to conduct a series of PSPW fermentation for obtaining high-value SCP by optimizing fermentation conditions. The yeast combination was optimized as Candida utilis , Geotrichum candidum and Candida tropicalis with the volume proportion of 9:5:1. The inoculum size, temperature, rotation speed and initial pH were optimized at 12 %, 24℃, 200 r·min−1 and ∼ 4.13 (natural pH), respectively. At the optimal conditions, SCP yield of 3.06 g·L−1 and water-soluble protein of 17.32 % were obtained with the chemical oxygen demand removal of 56.9 %. A resource-recycling process of PSPW was proposed by coupling yeast fermentation and up-flow anaerobic sludge blanket (UASB) treatment to achieve simultaneous high-level organic removal and SCP production, which could be a promising alternative technology for PSPW treatment. [ABSTRACT FROM AUTHOR]

Microbial community structure of sludge sampled from an UASB treating potato starch processing wastewater (PSPW) was investigated. Operational taxonomic units revealed at 97% sequence identity tolerance was 2922, 2869 and 3919 for bottom, middle and top sections of the reactor, respectively. Overall abundant phylum observed within the UASB was low-G + C-Gram-positive bacteria affiliated to Firmicutes (26.01%) followed by Chloroflexi (16.70%), Proteobacteria (12.71%), Cloacimonetes (10.72%), Bacteroidetes (7.87%), Synergistetes (9.02%) and Euryarchaeota (8.82%). Whiles Firmicutes had dominated the bottom and top section by 34.01% and 28.64%, respectively, middle section was predominantly Euryarchaeota (24.32%) with major dominance in methanogens affiliated to genus Methanosaeta . The results demonstrated substantial stratification of the microbial community structure along the reactor height with various functional bacterial groups which subsequently allowed degradation of organics in PSPW in sequential mode. The findings herein would provide guidance for optimizing the anaerobic process and operation of the UASB. [ABSTRACT FROM AUTHOR]

Three-layered feedforward backpropagation (BP) artificial neural networks (ANN) and multiple nonlinear regression (MnLR) models were developed to estimate biogas and methane yield in an upflow anaerobic sludge blanket (UASB) reactor treating potato starch processing wastewater (PSPW). Anaerobic process parameters were optimized to identify their importance on methanation. pH, total chemical oxygen demand, ammonium, alkalinity, total Kjeldahl nitrogen, total phosphorus, volatile fatty acids and hydraulic retention time selected based on principal component analysis were used as input variables, whiles biogas and methane yield were employed as target variables. Quasi-Newton method and conjugate gradient backpropagation algorithms were best among eleven training algorithms. Coefficient of determination ( R 2 ) of the BP-ANN reached 98.72% and 97.93% whiles MnLR model attained 93.9% and 91.08% for biogas and methane yield, respectively. Compared with the MnLR model, BP-ANN model demonstrated significant performance, suggesting possible control of the anaerobic digestion process with the BP-ANN model. [ABSTRACT FROM AUTHOR]

[Display omitted] • Cu+-cysteine/Cu2+-cysteine complex is formed by adding Cu2+ into cysteine-rich medium. • Cu+-cysteine/Cu2+-cysteine complex enhances the activity of ctf AB. • Cu+-cysteine/Cu2+-cysteine complex catalyze cysteine oxidation and NADH regeneration. • The upgraded ctf AB and NADH/NAD+ improve butanol production. Butanol production from rice straw via Acetone-Butanol-Ethanol (ABE) fermentation has been considered a sustainable and cost-effective approach to cope with energy crisis and environmental issues. However, a number of factors, particularly low butanol production and energy-intensive separation, impede its industrial application. In this study, Cu2+, Zn2+, Fe2+, and Ni2+ were individually induced into the ABE fermentation system of Clostridium beijerinckii NCIMB 8052 with butyric acid and sugars both from rice straw as co-substrates to increase the specific butanol yield. The results demonstrated that the additional 0.20 g/L Cu2+ (i.e. 1.25 mmol/L) significantly increased SBY and butanol/acetone to 0.194 ± 0.006 g/g rice straw and 3.90 ± 0.21, respectively, compared to those of 0.126 ± 0.004 g/g rice straw and 2.61 ± 0.17 in control system. The improved butanol production was attributed to the formation of Cu2+-cysteine/Cu+-cysteine complex, which enhanced the adsorption of butyrate from rice straw by upgrading the activity of key enzyme (ctf AB) and NADH/NAD+. The study provides a reinforcement strategy for efficient lignocellulosic butanol production. [ABSTRACT FROM AUTHOR]

To predict the dynamic profiles in volatile fatty acids (VFAs) with pH and hydraulic retention time (HRT) during the startup of a 4-compartment ABR, a mathematical model was constructed by introducing pH and thermodynamic inhibition functions into the biochemical processes derived from the ADM1. The calibration of inhibition parameter for propionate uptake effectively improved the prediction accuracy of VFAs. The developed model could simulate the VFAs profiles very well no matter the observable change of pH or/and HRT. The simulation results indicated that both H 2 -producing acetogenesis and methanogenesis in the ABR would be inhibited with a pH less than 4.61, and the propionate oxidation could be thermodynamically restricted even with a neutral pH. A decreased HRT would enhanced the acidogenesis and H 2 -producing acetogenesis in the first 3 compartments, but no observable increase in effluent VFAs could be found due to the synchronously enhanced methanogenesis in the last compartment. [ABSTRACT FROM AUTHOR]

Anaerobic baffled reactors (ABRs) have been widely used in engineering but very few models have been developed to simulate its performance. Based on the integration of biomass retention and liquid–gas mass transfer of biogas into the biochemical process derived in the International Water Association (IWA) Anaerobic Digestion Model No.1 (ADM1), a mathematical model was developed to predict volatile fatty acids (VFAs), chemical oxygen demand (COD Cr ) and biogas in a 4-compartment ABR operated with variable hydraulic retention time (HRT). The model was calibrated and validated with the experimental data obtained from the reactor when the HRT decreased from 2.0 to 1.0 d by stages. It was found that the predicted VFAs, COD Cr and biogas agreed well with the experimental data. Consequently, the developed model was a reliable tool to enhance the understanding among the mechanisms of the anaerobic digestion in ABRs, as well as to reactor’s designing and operation. [ABSTRACT FROM AUTHOR]

Anaerobic baffled reactors (ABRs) have been widely used in engineering but very few models have been developed to simulate its performance. Based on the integration of biomass retention and liquid–gas mass transfer of biogas into the biochemical process derived in the International Water Association (IWA) Anaerobic Digestion Model No.1 (ADM1), a mathematical model was developed to predict volatile fatty acids (VFAs), chemical oxygen demand (COD Cr ) and biogas in a 4-compartment ABR operated with variable hydraulic retention time (HRT). The model was calibrated and validated with the experimental data obtained from the reactor when the HRT decreased from 2.0 to 1.0 d by stages. It was found that the predicted VFAs, COD Cr and biogas agreed well with the experimental data. Consequently, the developed model was a reliable tool to enhance the understanding among the mechanisms of the anaerobic digestion in ABRs, as well as to reactor’s designing and operation. [ABSTRACT FROM AUTHOR]

• A new high-reliability algorithm is proposed to estimate Monod kinetic parameters. • A kinetics-based model is developed to quantify the nitrogen metabolic network. • Simultaneous PN/A and PDN/A are identified in the single-stage continuous system. • Anammox's DO half-inhibition constant is firstly evaluated to be 0.37-0.60 mg L−1. A single-stage intermittent aeration microaerobic reactor (IAMR) has been developed for the cost-effective nitrogen removal from piggery wastewater with a low ratio of chemical oxygen demand (COD) to total nitrogen (TN). In this study, a quantified nitrogen metabolic network was constructed based on the metagenomics, reaction kinetics and mathematical model to provide a revealing insight into the nitrogen removal mechanism in the IAMR. Metagenomics revealed that a complex nitrogen metabolic network, including aerobic ammonia and nitrite oxidation, anammox, denitrification via nitrate and nitrite, and nitrate respiration, existed in the IAMR. A novel method for solving kinetic parameters with high stability was developed based on a genetic algorithm. Use this method to calculate the kinetics of various reactions involved in nitrogen metabolism. Kinetics revealed that simultaneous partial nitritation-anammox (PN/A) and partial denitrification-anammox (PDN/A) were the dominant approaches to nitrogen removal in the IAMR. Finally, a kinetics-based model was proposed for quantitatively describing the nitrogen metabolic network under the limitation of COD. 58% ∼ 67% of nitrogen was removed via the anammox-based processes (PN/A and PDN/A), but only 7% ∼ 12% and 1% ∼ 2% of nitrogen were removed via heterotrophic denitrification of nitrite and nitrate, respectively. The half-inhibition constant of dissolved oxygen (DO) on anammox was simulated as 0.37 ∼ 0.60 mg L−1, filling the gap in quantifying DO inhibition on anammox. High-frequency intermittent aeration was identified as the crucial measure to suppress nitrite-oxidizing bacteria, although it has a high affinity for DO and NO 2 −-N. In continuous aeration mode, the simulated NO 3 −-N in the IAMR would rise by 39.6%. The research provides a novel insight into the nitrogen removal mechanism in single-stage microaerobic systems and provides a reliable approach to practicing PN/A and PDN/A for cost-effective nitrogen removal. [Display omitted] [ABSTRACT FROM AUTHOR]

Swine manure is a significant reservoir for antibiotic resistance. Anaerobic digestion (AD) is a common biological process used to treat swine manure but still faces low efficiencies in biogas production and antibiotic resistance removal. It is here shown that AD with free nitrous acid pretreatment (FNA) was effective in reducing antibiotic resistance genes (ARGs) in swine manure. FNA pretreatment (nitrite =250 mg N/L, pH=5.0, temperature=20 ± 1 °C) simultaneously reduced antibiotics (Tetracyclines, Quinones and Sulfonamides), inactivated antibiotics resistance bacteria (ARB) by 0.5–3 logs, and decreased ARGs tet , sul and qnr by 1–2, 1–3 and 0.5 logs, respectively. In the following AD step, the total residual ARGs was reduced to ~3.49 × 107 gene copies/g dry total solids (TS), ~1 log lower than that in the AD without pretreatment (3.55 ×108 gene copies/g dry TS). Microbial community and network analyses revealed that the ARG removal was mainly driven by the direct FNA effect on reducing ARGs and antibiotics, not related to ARB. Besides, the FNA pretreatment doubled biochemical methane production potential from swine manure. Together these results demonstrate that AD with FNA pretreatment is a useful process greatly facilitating swine manure management. [Display omitted] • FNA pretreatment simultaneously reduces antibiotics, ARB and ARG in swine manure. • FNA pretreatment improves ARG reduction by at least 1 log in the following AD. • The ARG removal is mainly driven by the FNA effect on reducing ARG and antibiotics. • FNA pretreatment doubles methane production potential from swine manure. [ABSTRACT FROM AUTHOR]

High-input agriculture in China has successfully increased crop productivity in the past decades, but at a significant environmental cost. It is essential to improve management strategies to mitigate greenhouse gas (GHG) emissions and other environmental costs, while maintaining grain yields. However, there is a lack of studies to evaluate mitigation strategies under long-term climate variability. This paper combines field experimental data and soil–plant systems modeling to investigate the potential for improving water and nitrogen management of a wheat–maize double cropping system in North China Plain. The APSIM model was calibrated against the data and then applied to simulate crop yield and N 2 O emissions from soil in response to irrigation and nitrogen inputs. Our results show that the N fertilizer rate and irrigation amount under the local farmer practice could be reduced by 28% and 14% without sacrificing crop yield. This in turn led to a reduction in GHG emissions by 31%, mainly attributed to the decrease in emissions from the production and transportation of N fertilizer and direct N 2 O emissions from soil. Additionally, the results indicate that the direct N 2 O emissions from soil was positively correlated with N inputs, implying an increasing emission factor (N 2 O produced per unit of N input) with N application rates. It is concluded that potential exists to optimize N fertilizer rate and irrigation amount to reduce GHG emissions while still maintaining crop yield in the agro-ecosystems in North China Plain. [ABSTRACT FROM AUTHOR]

A novel upflow microaerobic sludge reactor (UMSR) was constructed to treat manure-free piggery wastewater with high NH 4 + -N concentration and low COD/TN ratio, and the effect and biological mechanism of COD/TN ratio on nitrogen removal were investigated at a constant hydraulic retention time of 8 h and 35 °C. The results showed that the UMSR could treat the wastewater with a better synchronous removal of COD, NH 4 + -N and TN. The microaerobic UMSR allowed nitrifiers, and heterotrophic and autotrophic denitrifiers to thrive in the flocs, revealing a multiple nitrogen removal mechanism in the reactor. Both the nitrifiers and denitrifiers would be restricted by an influent COD/TN ratio more than 0.82, resulting in a decrease of TN removal in the UMSR. To get a TN removal over 80% with a TN load removal above 0.86 kg/(m 3 ·d) in the UMSR, the influent COD/TN ratio should be less than 0.70. [ABSTRACT FROM AUTHOR]

Recently chalcogenide phase-change resist Ge 2 Sb 2(1− x ) Bi 2 x Te 5 , which is compatible in next generation full-vacuum microelectronic manufacturing, has been paid much more attention due to the its excellent properties, such as high etching selectivity between Si and Ge 2 Sb 2(1− x ) Bi 2 x Te 5 (about 500), wide spectral absorption and able to be prepared in vacuum. However, the very low developing selectivity (lower than 5) between its crystalline and amorphous phase limits its application in lithography. Here we developed a novel high-selective developing method to significantly improve the selectivity up to 22 (5 times than before), which enables the inorganic resist to be workability. Moreover, the developing mechanism is revealed, and this is helpful to dry developing technology of Ge 2 Sb 2(1− x ) Bi 2 x Te 5 . [ABSTRACT FROM AUTHOR]

Fermentation of glucose influences CO assimilation to acetate in homoacetogens. Blautia coccoides was investigated for a better understanding of the metabolic characteristics of homoacetogens in mixotrophic cultures. Batch cultures of the strain with H/CO as a sole carbon source reached an acetate yield of 5.32 g/g dry cell weight after 240 h of incubation. Autotrophic metabolism was inhibited as glucose was added into the culture: the higher the glucose concentration the lower the autotrophic ability of the bacterium. Autotrophy was inhibited by high glucose concentration, probably due to the competition for coenzyme A between the Embden-Meyerhof-Parnas pathway and the Wood-Ljungdahl carbon fixation pathway, the energy (adenosine triphosphate) allocation for synthesis of cell carbon and reduction of CO, in combination with the low pH caused by the accumulation of acetate. [ABSTRACT FROM AUTHOR]

The paper studied accumulation of denitrifying polyphosphate-accumulating organisms (DNPAOs) by using an improved sequencing batch reactor (SBR) system in which anaerobic-aerobic-anoxic (A-O-A) and anaerobic-anoxic (A–A) are at low temperature (15 °C). Results indicated that it was feasible to accumulate DNPAOs with nitrogen (N) and phosphorus (P) removals concurrently in an improved SBR system. Moreover, a DNPAOs strain was isolated from the accumulation and was identified as Acinetobacter sp. J6. Important factors that affect N and P removal efficiency of strain J6 were investigated, including temperature, pH and total phosphate (TP) concentration. Strain J6 had the highest N and P removal rates under original pH 8.0, TP concentration 4.16 mg L −1 and 15 °C. The purification culture of strain J6 contributed to the germplasm resources for a full-scale biological N and P removal system to denitrify and remove phosphate simultaneously. [ABSTRACT FROM AUTHOR]

Combined anaerobic–aerobic processes are efficacious and economic approaches in treating swine wastewater. Nitrogen removal efficiency of these processes, however, is usually limited due to the low carbon/nitrogen (C/N) ratio of the wastewater. An innovative wood-chip-framework soil infiltrator (WFSI) was developed and its performance in treating anaerobic digested swine wastewater was investigated. The WFSI showed comparable removal of chemical oxygen demand (COD) and amongst the highest efficiency of nitrogen removal in treating low C/N wastewater. At a COD volume loading rate of 98.6 g/m 3 d the WFSI could remove up to 47.7 g/m 3 d of COD. Removal rates of NH 4 + -N and total nitrogen, also reached 69.1 and 30.4 g/m 3 d, respectively, when NH 4 + -N loading rate was 88.4 g/m 3 d. Biological analysis indicated that aerobic, anoxic and anaerobic microbiota occurred throughout the WFSI. Abundant cellulose and lignin decomposing bacteria could degrade the wood chips and provided extra carbon source to enhance denitrification. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel SBR-UMSR process was constructed to treat manure-free piggery wastewater. • The front-end SBR functioned as a COD remover to get an effluent with a COD/TN ≤ 1. • Partial nitrification – anammox process was well performed in the back-end UMSR. • Effective synchronous removal of COD and TN was achieved in the combined process. • COD, NH 4 +-N and TN in effluent all well met the strict discharge standard of China. A novel combined sequencing batch reactor (SBR) – up-flow microaerobic sludge reactor (UMSR) process was developed to treat manure-free piggery wastewater characterized by low COD/TN ratio and high NH 4 +-N. The front-end SBR was designed to get an effluent with COD/TN ≤ 1 by removing COD, allowing the back-end UMSR to practice anammox for the simultaneous removal of TN and NH 4 +-N. Fed with the raw piggery wastewater, the combined SBR-UMSR process was started up at 27℃ with a reflux ratio of 15:1 in the UMSR. After 230-days running, the removal of COD, TN, and NH 4 +-N in the combined SBR-UMSR process reached 78.41%,85.05%, and 92.21%, respectively. 50.22% of COD in the wastewater was removed in the SBR, while 87.11% of NH 4 +-N and 79.69% of TN were removed in the UMSR. Stoichiometry and bacterial function analysis revealed that the partial nitrification – anammox process was the dominant nitrogen removal approach in the UMSR. [ABSTRACT FROM AUTHOR]

This study was conducted to identify the optimum pH range and the appropriate buffer for butyric acid production from rice straw by fermentation using an undefined mixed culture. A series of experiments conducted at pH levels of 5.0 ~ 7.0 showed that neutral pH improved rice straw conversion and consequently carboxylic acid production. The highest butyric acid production (up to 6.7 g/L) was achieved at pH of 6.0 ~ 6.5, while it was only 1.7 g/L without pH control or at pH 5.0. Another series of experiments conducted at pH 6.0 ~ 6.5 buffered with CaCO, NaHCO, NHHCO and their combinations indicated that different buffers had different effects onthe product spectrum, and that CaCO combined with NaHCO was an effective buffer for butyric acid production. The highest total volatile fatty acids (about 12.6 g/L) production and one of the two highest butyric acid concentrations (about 7.6 g/L) were obtained by buffering with CaCO combined with NaHCO. PCR-DGGE analysis revealed that different pH and buffers also influenced the microbial population distribution. Bacteria were suppressed at low pH, while the bacterial community structures at higher pH varied slightly. Overall, this study presents an alternative method for butyric acid production from lignocellulosic biomass without supplementary cellulolytic enzyme. [ABSTRACT FROM AUTHOR]

Sustainable vehicle fuel is indispensable in future due to worldwide depletion of fossil fuel reserve, oil price fluctuation and environmental degradation. Microbial production of butanol from renewable biomass could be one of the possible options. Renewable biomass such as corn stover has no food deficiency issues and is also cheaper in most of the agricultural based countries. Thus it can effectively solve the existing issue of substrate cost. In the last 30 years, a few of Clostridium strains have been successfully implemented for biobutanol fermentation. However, the commercial production is hindered due to their poor tolerance to butanol and inhibitors. Metabolic engineering of Clostridia strains is essential to solve above problems and ultimately enhance the solvent production. An effective and efficient pretreatment of raw material as well as optimization of fermentation condition could be another option. Furthermore, biological approaches may be useful to optimize both the host and pathways to maximize butanol production. In this context, this paper reviews the existing Clostridium strains and their ability to produce butanol particularly from corn stover. This study also highlights possible fermentation pathways and biological approaches that may be useful to optimize fermentation pathways. Moreover, challenges and future perspectives are also discussed. [ABSTRACT FROM AUTHOR]

A biofilm-based anaerobic-aerobic (A2O2) reactor was constructed to treat manure-free piggery wastewater. The reactor contained four compartments, among which the first two were anaerobic (A phase) and the last two were aerobic (O phase). Throughout around one-year operation, high-level nutrient removal was demonstrated. At an optimal reflux ratio of 100%, the average NH 4 +-N, TN, and COD removal efficiencies were high as 99.4%, 91.7%, and 79.4%, respectively, with the influent concentration of 220.6, 231.6 and 332 mg/L, respectively. The NH 4 +-N, TN, and COD concentrations in the final effluent were only 1.4, 18.5 and 65 mg/L, respectively. COD and nitrogen removal were mainly removed in the A phase and O phase, respectively. This result revolutionizes the previous perception that nitrogen is only removed in the A phase of conventional A-O configuration. Achievement of PN/A in the O phase was critical to the efficient nitrogen removal. Heterotrophic denitrification in the anaerobic compartments removed the nitrate produced by anammox, ensuring the high-level nitrogen removal. Anaerobic organic degradation was a major pathway for COD removal, as abundant methanogens detected in the A phase. This study provides a feasible technical scheme for the efficient nutrient removal from ammonium-rich wastewater. [Display omitted] • A biofilm-based anaerobic-aerobic (A2O2) reactor is built to treat real wastewater. • N and COD removal are high as 91.7% and 80.0% at the optimal reflux ratio of 100%. • Anaerobic organic degradation in A phase is a major pathway for COD removal. • Partial nitrification-anammox in O phase is responsible for N removal. • Denitrification in A phase further ensures the high-level N removal. [ABSTRACT FROM AUTHOR]

A biofilm-based anaerobic-aerobic (A2O2) reactor was constructed to treat manure-free piggery wastewater. The reactor contained four compartments, among which the first two were anaerobic (A phase) and the last two were aerobic (O phase). Throughout around one-year operation, high-level nutrient removal was demonstrated. At an optimal reflux ratio of 100%, the average NH 4 +-N, TN, and COD removal efficiencies were high as 99.4%, 91.7%, and 79.4%, respectively, with the influent concentration of 220.6, 231.6 and 332 mg/L, respectively. The NH 4 +-N, TN, and COD concentrations in the final effluent were only 1.4, 18.5 and 65 mg/L, respectively. COD and nitrogen removal were mainly removed in the A phase and O phase, respectively. This result revolutionizes the previous perception that nitrogen is only removed in the A phase of conventional A-O configuration. Achievement of PN/A in the O phase was critical to the efficient nitrogen removal. Heterotrophic denitrification in the anaerobic compartments removed the nitrate produced by anammox, ensuring the high-level nitrogen removal. Anaerobic organic degradation was a major pathway for COD removal, as abundant methanogens detected in the A phase. This study provides a feasible technical scheme for the efficient nutrient removal from ammonium-rich wastewater. [Display omitted] • A biofilm-based anaerobic-aerobic (A2O2) reactor is built to treat real wastewater. • N and COD removal are high as 91.7% and 80.0% at the optimal reflux ratio of 100%. • Anaerobic organic degradation in A phase is a major pathway for COD removal. • Partial nitrification-anammox in O phase is responsible for N removal. • Denitrification in A phase further ensures the high-level N removal. [ABSTRACT FROM AUTHOR]

[Display omitted] • A CEF process was optimized for the effective co-production of butanol and H 2. • The optimized CEF process manipulated the microbial metabolism more effectively. • The butanol production reached 10.85 g/L with a yield of 0.40 g/g-glucose. • The H 2 production reached 4.33 L/L with a yield of 161.69 mL/g-glucose. • The ER and ERE was as high as 446.90 kJ/L-medium and 95.85 %, respectively. To develop an effective acetone-butanol-ethanol (ABE) fermentation process for the enhanced co-production of butanol and H 2 , a series of neutral red mediated cathodic electro-fermentation (CEF) processes of Clostridium beijerinckii NCIMB 8052 were conducted with/without exogenous butyric acid as the co-substrate of glucose. The cathode potential, NR dosage, glucose concentration and exogenous butyric acid concentration were optimized progressively. The results showed that the most favorable cathode potential, NR dosage, glucose concentration and exogenous butyric acid was -0.60 V (vs Ag/AgCl), 0.50 mmol/L, 30 g/L and 3.00 g/L, respectively. With the optimal condition, the metabolism in the CEF process of C. beijerinckii NCIMB 8052 was well manipulated, resulting the excellent production of butanol and H 2 as high as 10.85 ± 0.45 g/L and 4.33 ± 0.40 L/L-medium, respectively. The excellent butanol yield of 0.40 ± 0.00 g/g-glucose (0.60 ± 0.01 mol-C/mol-C) and H 2 yield of 161.69 ± 19.28 mL/g-glucose resulted an energy recovery (ER) and energy recovery efficiency (ERE) as high as 446.90 ± 21.39 kJ/L-medium and 95.85 ± 1.62%, respectively. The optimized CEF process demonstrates an effective approach to manipulating the microbial metabolism of Clostridia for the enhanced co-production of butanol and H 2. [ABSTRACT FROM AUTHOR]

Modelling approaches have already been used to quantitatively assess the trade-offs between crop yield and N 2 O emissions as impacted by management practices. However, the model's performance in terms of predicting N 2 O emissions was mainly assessed against total emissions per growing season or year, which may reduce accuracy in modelling due to the uncertainties in total emissions estimated using the manual (static) chamber method. Here, a comparison between optimizations for Agricultural Production Systems sIMulator (APSIM) with total N 2 O emissions and daily N 2 O emissions was conducted. We further used the validated model to develop simple surrogate models for estimating total N 2 O emissions in different years and target potential opportunities to reduce N 2 O emissions while still maintaining the grain yield under long-term climatic conditions. Five parameters relating to denitrification and nitrification were optimized using differential evolution algorithm for global optimization based on two-year field experimental data at Huantai site in North China Plain, and comprehensive simulation experiments were further conducted under long-term climate variability in an irrigated wheat–maize rotation system. The method of Levenberg-Marquardt was implemented to fit simple surrogate models for estimating total N 2 O emissions in different years, and Analysis of Variance was used for model comparison. APSIM model optimized with daily N 2 O emissions could better simulate soil N 2 O and nitrate dynamics than that optimized with total N 2 O emissions. We obtained the posterior distributions of five key parameters to which N 2 O emissions are sensitive, and demonstrated that original model using default parameters could underestimate the rate of nitrification and denitrification and the subsequent N 2 O emissions. Total N 2 O emissions increased exponentially with nitrogen application rate and mean temperature, and IPCC (1% emission factor) could underestimate whole-year N 2 O emissions when N rate was higher than the optimized nitrogen rate for crop production. We also found that there was potential to optimize nitrogen fertiliser rate to reduce N 2 O emissions while still maintaining crop yield in the irrigated wheat–maize rotation system. This study demonstrated the necessity of optimization with daily N 2 O emissions in improving model accuracy, and the posterior distributions of five parameters relating to N 2 O emissions offered reference range for future model improvement and applications. [Display omitted] • Crop yield and soil N 2 O emissions were studied using a modelling approach. • APSIM could more accurately model soil N 2 O and nitrate dynamics when five related parameters were optimized with daily N 2 O emissions. • Posterior distributions of five parameters controlling N 2 O dynamics were obtained. • Total N 2 O emissions increased exponentially with N rate and mean temperature. • N rate could be reduced by 19% without sacrificing crop yield, which in turn led to a reduction of N 2 O emissions by 34%. [ABSTRACT FROM AUTHOR]

[Display omitted] • CdS NPs was in situ formed by C. beijerinckii NCIMB 8052 in ABE fermentation. • Hybrid CdS@ C. beijerinckii was self-assembled with the NPs attached to cell surface. • Insufficient NADH restricted the butanol synthesis in C. beijerinckii NCIMB 8052. • NADH/NAD+ in the CdS@ C. beijerinckii was upgraded by the in situ formed CdS NPs. • Lignocellulosic butanol was improved by 23.6% in the hybrid CdS@ C. beijerinckii. Bioproduction of butanol from lignocellulose has been considered as a sustainable and eco-friendly technology to cope with energy crisis and environmental issues. In the present research, a novel CdS@ C. beijerinckii hybrid system was assembled by combining Clostridium beijerinckii NCIMB 8052 and the in situ formed CdS nanoparticles (NPs) to enhance the butanol production in ABE fermentation. 0.1 g/L of Cd(NO 3) 2 ·4H 2 O was identified for the effective in situ formation of CdS NPs. The in situ formed CdS NPs was powerful in generating photoelectrons which resulted in a significant upgradation of NADH/NAD+ in C. beijerinckii NCIMB 8052 under the visible irradiation of 2000 W/m2. With glucose and butyric acid as co-substrates, butanol production in the fermentation system of hybrid CdS@ C. beijerinckii reached 10.42 ± 0.15 g/L, much higher than that of 8.08 ± 0.13 g/L in the fermentation system of C. beijerinckii NCIMB 8052. Butanol production from the mixed carbon source of saccharified liquid and acidogenic fermentation broth of rice straw was also improved by 23.6% in the hybrid system of CdS@ C. beijerinckii , comparing to that of C. beijerinckii NCIMB 8052. The upgraded NADH/NAD+ was confirmed as the dominant factor for the enhanced butanol production. The research work provided an efficient fermentation process for the production of lignocellulosic butanol. [ABSTRACT FROM AUTHOR]

Four new 1,8-naphthyridine derivatives were synthesized by reacting the parent molecules with aldehydes and characterized. Two of the compounds have completely new and unusual skeletons, and display red-fluorescence emissions and two-photon absorption. Their structures were determined using MS, 1D and 2D NMR, and density functional theory calculations. The structural investigations of 2-methyl-1,8-naphthyridine hydrochloride and hydrobromide showed that abundant hydrogen-bonds and π- π interactions lead to extended networks. [ABSTRACT FROM AUTHOR]

Abstract: Hexagonal LaPO4·nH2O:Eu3+ nano-wires and dual-phase LaPO4:Eu3+ nano-wires with hexagonal and monoclinic structures were synthesized by hydrothermal reaction at 150 and 220°C, respectively. The effects of high temperature treatment on the structure, morphology and photoluminescence of the specimens were also investigated with X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and fluorescence spectrophotometer (FL). The results indicated the phase transformation for LaPO4:Eu3+ from the hexagonal structure to the monoclinic structure occurred, after the specimens were calcined at 900°C for 12h in the air. The wire-like structures of LaPO4:Eu3+ were destroyed and transformed into particle-like structures at high temperature. The mechanism of transformation from nano-wires to particles was introduced briefly. The photoluminescence properties of as-prepared and annealed specimens were also discussed in detail. [ABSTRACT FROM AUTHOR]