Mechanisms of anaerobic treatment of sulfate-containing organic wastewater mediated by Fe0 under different initial pH values.

The anaerobic treatment of sulfide-containing organic wastewater (SCOW) is significantly affected by pH, causing dramatic decrease of treatment efficiency when pH deviates from its appropriate range. Fe0 has proved as an effective strategy on mitigating the impact of pH. However, systematic analysis of the influence mechanism is still lacking. To fill this gap, the impact of different initial pH values on anaerobic treatment efficiency of SCOW with Fe0 addition, the change of fermentation type and methanogens, and intra-extracellular electron transfer were explored in this study. The results showed that Fe0 addition enhanced the efficacy of anaerobic treatment of SCOW at adjusted initial pH values, especially at pH 6. Mechanism analysis showed that respiratory chain-related enzymes and electron shuttle secretion and resistance reduction were stimulated by soluble iron ions generated by Fe0 at pH 6, which accelerated intra-extracellular electron transfer of microorganisms, and ultimately alleviated the impact of acidic pH on the system. While at pH 8, Fe0 addition increased the acetogenic bacteria abundance, as well as optimized the fermentation type and improved the F420 coenzyme activity, resulting in the enhancement of treatment efficiency in the anaerobic system and remission of the effect of alkaline pH on the system. At the neutral pH, Fe0 addition had both advantages as stimulating the secretion of respiratory chain and electron transfer-related enzymes at pH 6 and optimizing the fermentation type pH 8, and thus enhanced the treatment efficacy. This study provides important insights and scientific basis for the application of new SCOW treatment technologies.

Study on the treatment of corn alcohol wastewater by the internal circulation anaerobic reactor.

To comprehensively assess the efficacy of employing the internal circulation (IC) anaerobic reactor for corn alcohol wastewater treatment and investigate its feasibility, this study focused on anaerobic digestion parameters, energy balance, and the composition of the prokaryotic microbial community. During the operation of the reactor, the hydraulic retention time was progressively reduced from 4.8 to 1.6 days while achieving an average organic loading rate of 12.46 kg chemical oxygen demand (COD)/(m3·d). Moreover, the removal rate of COD exceeded 98%, and the energy balance (ΔE) reached 10.29 kJ/g fed COD. The initial manifestation of organic acidosis in the reactor was a decline in gas production, which is primarily caused by propionic acid accumulation. The subsequent analysis revealed a high diversity of prokaryotes in granular sludge, with the predominant archaea primarily involved in methane production through the acetic acid pathway. The IC anaerobic reactor shows exceptional performance in treating corn alcohol wastewater by optimizing its operating conditions. Energy balance analysis confirmed the feasibility of the process. The findings of this study may offer valuable insights for optimizing control strategies and engineering applications.

A challenge in anaerobic digestion of swine wastewater: recalcitrance and enhanced-degradation of dietary fibres.

Dietary fibres are main substances in the pig's feed. Because of the recalcitrance, they could enter swine wastewater and become a serious obstruction factor for the anaerobic digestion process. In this work, three dietary fibres abundant in pig feedstocks: Wheat Bran Fibre (WBF), Alfalfa Fibre (AF) and Rice Chaff Fibre (RCF) were chosen and their anaerobic degradability was determined. The results showed that the biochemical methane potential in 10 days (BMP10) of WBF, AF and RCF was 258, 176 and 86 mL/g-VS, respectively. The size, purity, crystallinity, and lignin coating in particular, were found having influences on the anaerobic biodegradability of dietary fibres. To surprise, a negative rather than positive effect was observed for the direct addition of extraneous cellulase into the anaerobic digestion systems, leading to a longer lag time and a smaller BMP10. The enhancement was achieved for the addition of extraneous bacteria in the form of anaerobic granular sludge (AnGS), shortening the lag time of WBF and AF by 36% and 13%, respectively. By high-throughput sequencing analysis, abundant protein and amino acids degraders found in anaerobic activated sludge (AnAS) could degrade the exogenous enzymes. Abundant members affiliated to the family Anaerolineaceae, and Syntrophobacteraceae in AnGS, related to the cellulolytic and syntrophic activity respectively, probably contribute to the acceleration effect of AnGS.

Investigation of methanogenic community structures in rural biogas digesters from different climatic regions in Yunnan, southwest China.

Understanding of the microbial community structures of the biogas digesters in different climatic regions can help improve the methane production in the fermentation process. The methanogenic archaeal diversity in four rural biogas digesters (BNA, JSA, LJA, and XGA) was investigated by a culture-independent rRNA approach in different climatic regions in Yunnan. Community structure composed of 711 clones in the all libraries. A total of 33 operational taxonomic units (OTUs) were detected, and major groups of methanogens were the orders Methanosarcinales and Methanomicrobiales. 63.2 % of all archaeal OTUs belong to the order Methanosarcinales which mostly contain acetotrophic methanogens. Methanomicrobiales (19.5 % in all OTUs) were detected in considerable number. Additionally, there were minor rates of uncultured archaea. The principal component analysis indicated that the genus Methanosaeta was mainly affected by the fermentation temperatures.

Spiral-Pipe Gas Anaerobic Digester.

The reduction of carbon dioxide to methane using hydrogen is an important process in biogas production. However, designing gas anaerobic digesters (GADs) based on this reaction presents several challenges. In this study, we developed an innovative spiral-pipe gas anaerobic digester (SGAD) to increase the displacement distance between the bubbles, thus prolonging the gas retention time and facilitating the reduction of CO2 to CH4 via H2. The process was successfully demonstrated by using a CO2/H2 ratio of 1:3 and a gas-feeding rate of 3.9 L Lr -1 d-1. During the experiment, more than 98% of the CO2 and 96% of the H2 were consumed, resulting in biogas containing ca. 86-96% CH4. Additionally, we applied our proposed evaluation methodology for assessing GAD performance to evaluate the performance of the SGAD. This methodology serves as a reference for evaluating and designing GAD systems. The innovative design of the SGAD and the corresponding evaluation methodology offer new insights into the design of reactors.

Enhancing biomass and lipid accumulation by a novel microalga for unsterilized piggery biogas slurry remediation.

The cost and efficiency of an algal-BS treatment system are determined by the specific microalgal species and BS pretreatment method. This study examines the growth of a novel algae Chlorella sp. YSD-2 and the removal of nutrients from the BS using different pretreatment methods, including dilution ratio and sterilization. The highest biomass production (1.84 g L-1) was achieved in the 1:2 unsterilized biogas slurry, which was 2.03 times higher than that in the sterilized group, as well as higher lipid productivity (17.29 mg L-1 d-1). Nevertheless, the sterilized biogas slurry at a 1:1 dilution ratio exhibited the most notable nutrient-removal efficiency, with COD at 71.97%, TP at 91.32%, and TN at 88.80%. Additionally, the analysis of 16S rRNA sequencing revealed a significant alteration in the indigenous bacterial composition of the biogas slurry by microalgal treatment, with Proteobacteria and Cyanobacteria emerging as the predominant phyla, and unidentified_Cyanobacteria as the primary genus. These findings suggest that Chlorella sp. YSD-2 exhibits favorable tolerance and nutrient-removal capabilities in unsterilized, high-strength biogas slurry, along with high productivity of biomass and lipids. Consequently, these results offer a theoretical foundation for the development of an efficient and economically viable treatment method for algal-BS.

Biogas slurry application alters soil properties, reshapes the soil microbial community, and alleviates root rot of Panax notoginseng.

Background: Panax notoginseng is an important herbal medicine in China, where this crop is cultivated by replanting of seedlings. Root rot disease threatens the sustainability of P. notoginseng cultivation. Water flooding (WF) is widely used to control numerous soilborne diseases, and biogas slurry shows positive effects on the soil physiochemical properties and microbial community structure and has the potential to suppress soilborne pathogens. Hence, biogas slurry flooding (BSF) may be an effective approach for alleviating root rot disease of P. notoginseng; however, the underlying mechanism needs to be elucidated. Methods: In this study, we conducted a microcosm experiment to determine if BSF can reduce the abundance of pathogens in soil and, alleviate root rot of P. notoginseng. Microcosms, containing soil collected from a patch of P. notoginseng showing symptoms of root rot disease, were subjected to WF or BSF at two concentrations for two durations (15 and 30 days), after which the changes in their physicochemical properties were investigated. Culturable microorganisms and the root rot ratio were also estimated. We next compared changes in the microbial community structure of soils under BSF with changes in WF and untreated soils through high-throughput sequencing of bacterial 16S rRNA (16S) and fungal internal transcribed spacer (ITS) genes amplicon. Results: WF treatment did not obviously change the soil microbiota. In contrast, BSF treatment significantly altered the physicochemical properties and reshaped the bacterial and fungal communities, reduced the relative abundance of potential fungal pathogens (Fusarium, Cylindrocarpon, Alternaria, and Phoma), and suppressed culturable fungi and Fusarium. The changes in the microbial community structure corresponded to decreased root rot ratios. The mechanisms of fungal pathogen suppression by BSF involved several factors, including inducing anaerobic/conductive conditions, altering the soil physicochemical properties, enriching the anaerobic and culturable bacteria, and increasing the phylogenetic relatedness of the bacterial community. Conclusions: BSF application can reshape the soil microbial community, reduce the abundance of potential pathogens, and alleviate root rot in P. notoginseng. Thus, it is a promising practice for controlling root rot disease in P. notoginseng.

Identification of novel prognostic risk signature of breast cancer based on ferroptosis-related genes.

Ferroptosis is a type of cell regulated necrosis triggered by intracellular phospholipid peroxidation, which is more immunogenic than apoptosis. Therefore, genes controlling ferroptosis may be promising candidate biomarkers for tumor therapy. In this study, we investigate the function of genes associated with ferroptosis in breast cancer (BC) and systematically evaluate the relationship between ferroptosis-related gene expression and prognosis of BC patients from the Cancer Genome Atlas database. By using the consensus clustering method, 1203 breast cancer samples were clustered into two clearly divided subgroups based on the expression of 237 ferroptosis-related genes. Then differentially expressed analysis and least absolute shrinkage and selection operator were used to identify the prognosis-related genes. Furthermore, the genetic risk signature was constructed using the expression of prognosis-related genes. Our results showed that the genetic risk signature can identify patient subgroups with distinct prognosis in either training cohort or validation, and the genetic risk signature was associated with the tumor immune microenvironment. Finally, the Cox regression analysis indicated that our risk signature was an independent prognostic factor for BC patients and this signature was verified by the polymerase chain reaction and western blot. Within this study, we identified a novel prognostic classifier based on five ferroptosis-related genes which may provide a new reference for the treatment of BRCA patients.

High nitrite-nitrogen stress intensity drives nitrite anaerobic oxidation to nitrate and inhibits methanogenesis.

Nitrite is an important intermediate in nitrogen metabolism. We explored the effect of nitrite-nitrogen stress intensity (NNSI) on nitrite metabolism and methanogenesis in anaerobic digestion. The results showed that the NNSI regulated microbial diversity, composition, and functions, and microbial community assembly was primarily shaped by stochastic processes. Moreover, the NNSI was negatively correlated with α-diversity and positively correlated with non-metric multi-dimensional scaling distance. Denitrification gradually increased with increasing NNSI; however, methanogenesis was gradually inhibited, which was primarily due to the inhibition of the aceticlastic methanogenesis pathway (i.e., Methanosaeta) and methylotrophic methanogenesis pathway (i.e., Candidatus_Methanofastidiosum). High NNSI (1882 ± 98.99 mg/L NO2--N) promoted nitrite anaerobic oxidation to nitrate and was favorable for dissimilatory nitrate reduction to ammonia (DNRA). We present evidence for the microbial transformation of nitrite under anaerobic conditions, with potential geochemical and evolutionary importance. As nitrogen oxides were already present on early Earth, our finding presents the possibility of a nitrogen cycle before the evolution of oxygenic photosynthesis.

Catalytic hydrogenolysis of larix bark proanthocyanidins in ionic liquids produces UV blockers with potential for use in cosmetics.

The bark of larix, a major tree species in the coniferous forests of China's Greater Khingan Mountains, is typically treated as waste. The bark is, however, rich in flavonoids, known as proanthocyanidins, although their high degree of polymerization and high molecular weight reduce their biological activity and potential applications. Ionic liquids, a new type of "green solvent", characterized by low vapor pressure and good stability, have been developed and used as new solvents for naturally occurring macromolecules. Here, we used 1-butyl-3-methylimidazole chloride ([BMIM]Cl) as the ionic solvent to reduce the degree of polymerization of larix bark proanthocyanidins by Pd/C-catalyzed hydrogenolysis. The optimal reaction conditions, determined using an orthogonal experimental design, were: reaction temperature, 90 °C; reaction time, 1.5 h; catalyst loading, 4 g L-1 (Pd/C: [BMIM]Cl); and hydrogen pressure, 2.5 MPa. Characterization of the reaction products by UV-Vis and IR spectroscopy and gel permeation chromatographys showed that they retained the proanthocyanidin structure. We showed that whilst both the native and depolymerized proanthocyanidins were able to block UV light when added to commercially available skin creams and sunscreens, the depolymerized proanthocyanidins were more effective at a given concentration. This study expands the applications of a new "green" ionic liquid solvent, provides a technical foundation for the low-cost depolymerization of larix bark proanthocyanidins, and also explores a potential high-value use for waste larix bark as the source of a UV-blocking additive for cosmetics.

Enhanced anaerobic digestion of swine manure via a coupled microbial electrolysis cell.

Microbial electrolysis cell coupled anaerobic digestion (MEC-AD) is a new technology in energy recovery and waste treatment, which could be used to recycle swine manure. Here, different applied voltage effects were studied using MEC-AD with swine manure as a substrate. The maximum cumulative biogas and methane yields, both occurring with 0.9 V, were 547.3 mL/g total solid (TS) and 347.7 mL/g TS, respectively. The increased energy can counterbalance the electrical input. First order, logistic, gompertz, and back-propagation artificial neural network (BP-ANN) models were used to study cumulative biogas and methane yields. The BP-ANN model was superior to the other three models. The maximum degradation rate of hemicellulose, cellulose, and lignin was 60.97%, 48.59%, and 31.59% at 0.9 V, respectively. The BP-ANN model establishes a model for cumulative biogas and methane yields using MEC-AD. Thus, MEC-AD enhanced biogas and methane production and accelerated substrate degradation at a suitable voltage.

Comparison of long-term energy efficiency and microbial community dynamics of different reactors in response to increased loadings of water hyacinth juice.

Water hyacinth is considered to be among the worst invasive weed species globally, causing detrimental environmental and social problems worldwide. It rapidly grows, and therefore has significant potential as a resource. Due to its high moisture content (approximately 95%), the by-product obtained by dehydrating water hyacinth yields a considerable amount of water hyacinth juice (WHJ). In this study, we performed a comparative assessment of long-term energy efficiency, maximum treatment capacity limits, and microbial community dynamics of modified internal circulation (MIC) and up-flow anaerobic sludge blanket (UASB) reactors in response to increasing loadings of WHJ. The MIC reactor exhibited a higher energy recovery rate and stronger performance compared with the UASB reactor. The optimal organic loading rates of the MIC and UASB reactors were 17.93 and 8.85 kg chemical oxygen demand (COD)/m3/d, with methane conversion rates of 0.21 and 0.15 m3 CH4/kg COD, respectively. Furthermore, the engineering costs and project floor space required by the MIC reactor are less than those in the case of the UASB reactor. The high-throughput sequencing analysis indicated that the dominant phyla (e.g. Firmicutes and Bacteroidetes) were more abundant using the MIC reactor than with the UASB reactor, which may indicate WHJ degradation efficiency. Both reactors had similar predominant methanogens, suggesting that acetoclastic methanogenesis was the predominant metabolic pathway of methane formation. The results of this study provide new insights into the sustainable management of water hyacinth as a resource by establishing a regional ecosystem with biogas engineering applications.

Novel start-up process for the efficient degradation of high COD wastewater with up-flow anaerobic sludge blanket technology and a modified internal circulation reactor.

To avoid wastage of water resources and operating cost increases caused by the traditional start-up process of large amounts of dilution influent chemical oxygen demand (COD), a novel start-up process (NSP) was developed and verified with water hyacinth juice (WHJ) on an up-flow anaerobic sludge blanket (UASB) and modified internal circulation (MIC) reactor. Results show that UASB and MIC reactors were started successfully and that the MIC reactor exhibited a superior performance. The NSP time of the MIC reactor (46 days) was less than that of the UASB reactor (52 days), although the start-up organic loading rate (OLR) of the MIC reactor was higher than that of the UASB reactor. Interestingly, high-throughput sequencing analysis indicated that the reactor configuration significantly impacted the microbial diversity, however, the UASB and MIC reactors had similar predominant methanogens: Methanosaeta and Methanosarcina. Therefore, acetoclastic methanogenesis is the primary pathway of methane formation during WHJ treatment.

[Electrochemically active microorganisms and electrolytically assisted fermentative hydrogen production--a review].

Fermentative hydrogen production can be improved by electrolysis and electrochemically active microorganisms which are capable of using an electrode as an electron acceptor for the oxidation of organic matter, in particular, volatile acids produced after fermentation. Firstly volatile acids can be completely converted into CO2, electrons and protons on the surface of anode. Then the electrons flow to cathode through anode and wires, and at the same time the protons move to cathode through cation membrane between anode chamber and cathode chamber. Finally the electrons and the protons combine into hydrogen when they meet at the surface of cathode. In such a process, the fermentation barrier and the product inhibition can be avoided to improve the conversion of hydrogen. 8-9 mol H2/mol glucose of hydrogen potential can be obtained when glucose is used as substrate. This technology is very likely to be applied to produce hydrogen high efficiently from any energy crops, organic waste and wastewater.

Enhanced anaerobic treatment of swine wastewater with exogenous granular sludge: Performance and mechanism.

Anaerobic biotechnology has been widely used to the treatment of swine wastewater, but its organic loading rate is far lower than the expected. In this study, the fatigue effect was observed for indigenous anaerobic sludge (IAS) of anaerobic digestion system treating swine wastewater. On the contrary, the enhancement effect was demonstrated for exogenous granular sludge (EGS) originated from the internal circulation reactor treating pulping wastewater. The results showed the anaerobic digestion of swine wastewater with acclimatized EGS was much better than with IAS, 10th-day COD removal efficiency of 85% and 37% respectively. The better performance of acclimatized EGS was attributed to the more efficient degradation of volatile fatty acids (VFAs) as well as a stronger tolerance to the ammonia inhibition of swine wastewater. Revealed by molecular techniques, the acclimatized EGS contained more abundant syntrophic bacteria and methanogens than IAS. These functional microbes colonized in the acclimatized EGS could overcome the fatigue effect of IAS which contained a similar microbial community to pig gastrointestinal tract microbes. This study provides a feasible and promising way to enhance the efficiency of anaerobic digestion of swine wastewater.

Facile Synthesis of Carbon-Coated Porous Sb2Te3 Nanoplates with High Alkali Metal Ion Storage.

Constructing advanced anode materials with suitable operational potential and high energy density toward metal ion batteries is of significance for next-generation batteries. Carbon-coated porous Sb2Te3 nanoplates with high density and suitable operational potential, prepared by a hydrothermal and carbonization technique, manifest good electrochemical performance, including excellent rate capability, high capacities, and outstanding cycling performance. This performance can be traced to its special structure, including porous Sb2Te3 and the shell of carbon, which can provide fast charge transfer paths and maintain the structural stability for the entire material. The proposed strategy here of embedding porous high-density anode material in two-dimensional carbon provides a new avenue for designing anode materials with excellent gravimetric and volumetric capacities toward superior energy storage.

Optimization and kinetic study of methyl laurate synthesis using ionic liquid [Hnmp]HSO4 as a catalyst.

Methyl laurate was synthesized from lauric acid (LA) and methanol via an esterification reaction using ionic liquids (ILs) as catalysts. The efficiencies of three different catalysts, 1-methylimidazole hydrogen sulfate ([Hmim]HSO4), 1-methyl-2-pyrrolidonium hydrogen sulfate ([Hnmp]HSO4) and H2SO4, were compared. The effect of the methanol/LA molar ratio, reaction temperature, reaction time and catalyst dosage on the esterification rate of LA was investigated by single-factor experiments. Based on the single-factor experiments, the esterification of LA and methanol was optimized using response surface methodology. The results showed that the most effective catalyst was the IL [Hnmp]HSO4. The optimal conditions were as follows: [Hnmp]HSO4 dosage of 5.23%, methanol/LA molar ratio of 7.68 : 1, reaction time of 2.27 h and reaction temperature of 70°C. Under these conditions, the LA conversion of the esterification reached 98.58%. A kinetic study indicated that the esterification was a second-order reaction with an activation energy and a frequency factor of 68.45 kJ mol-1 and 1.9189 × 109 min-1, respectively. The catalytic activity of [Hnmp]HSO4 remained high after five cycles.

Spatiotemporal dynamics of bacterial and archaeal communities in household biogas digesters from tropical and subtropical regions of Yunnan Province, China.

A combination of 16S rRNA gene PCR-based techniques and the determination of abiotic factors were used to study community composition, richness, and evenness and the correlation between biotic and abiotic factors in 19 household biogas digesters in tropical and subtropical regions of Yunnan Province, China. The results revealed that both bacterial and archaeal community composition differed between regions and archaeal community composition was more affected by season than bacterial; regardless of sampling location, the dominant bacterial phyla included Chloroflexi, Bacteroidetes, Firmicutes, and Proteobacteria, and the most dominant archaeal phylum was Euryarchaeota; in digesters from both regions, Chloroflexi as the first or second most dominant bacteria accounted for 21.50-26.10 % of bacterial library sequences, and the phylum Crenarchaeota as the second most dominant archaea accounted for 17.65-19.77 % of archaeal library sequences; the species Methanosaeta concilii as the most dominant archaeal species accounted for 67.80-72.80 % of the sequences. This study found that most of the abundant microbial communities in 19 biogas digesters are similar, and this result will provide enlightenment for finding the universal nature in rural biogas digesters at tropical and subtropical regions in China.

Removal of phosphate from polluted water by lanthanum doped vesuvianite.

The adsorption capacities of vesuvianite and lanthanum doped vesuvianite were studied. The effects of different mass ratios of La/vesuvianite at different contact times, pHs, and temperatures on adsorption capacity were also studied. It was found that lanthanum doped vesuvianite exhibited higher adsorption capacity than undoped one due to the reaction of bounded lanthanum with phosphate. The adsorption capacity of lanthanum doped vesuvianite for phosphate removal increased with the increase of La/vesuvianite mass ratio. The Freundlich and Langmuir models were used to simulate the sorption equilibrium, and the results indicate that the Langmuir model had a better correlation with the experimental data than the Freundlich model did. When the initial phosphate concentration was 1mgP/L, the adsorptive capacity rate would be 1.32 mg P/g lanthanum doped vesuvianite (La/vesuvianite mass ratio >or=0.14) at pH between 6 and 9 after 40h. The concentrations of residual lanthanum ions in solution at different conditions were measured. Lanthanum doped vesuvianite was also used for the removal of phosphate in a polluted river water and it could be easily recycled once without losing its activity to a greater extent.