The differences in the competitive reactions of hydrogarnet and quicklime when reacting with titaniumcontaining and silicon-containing minerals during the Bayer digestion process were investigated.Thermodynamic analys...The differences in the competitive reactions of hydrogarnet and quicklime when reacting with titaniumcontaining and silicon-containing minerals during the Bayer digestion process were investigated.Thermodynamic analysis,artificial mineral experiments,and an evaluation of the digestion effect of natural diasporic bauxite were conducted.The results indicate that hydrogarnet shows a preferential reaction with anatase,and this preference becomes more pronounced as the silicon saturation coefficient increases.In contrast,quicklime participates in non-selective reactions with both anatase and desilication products(DSP).The preference of hydrogarnet for anatase significantly enhances the utilization efficiency of CaO in the high-temperature Bayer digestion process.展开更多
Yaks are well-adapted to the harsh environment of the Tibetan Plateau,and they emit less enteric methane(CH_(4))and digest poor-quality forage better than cattle.To examine the potential of yak rumen inoculum to mitig...Yaks are well-adapted to the harsh environment of the Tibetan Plateau,and they emit less enteric methane(CH_(4))and digest poor-quality forage better than cattle.To examine the potential of yak rumen inoculum to mitigate CH_(4)production and improve digestibility in cattle,we incubated substrate with rumen inoculum from yak(YRI)and cattle(CRI)in vitro in five ratios(YRI:CRI):(1)0:100(control),(2)25:75,(3)50:50,(4)75:25 and(5)100:0 for 72 h.The YRI:CRI ratios of 50:50,75:25 and 100:0 produced less total gas and CH_(4)and accumulated less hydrogen(H_(2))than0:100(control)at most time points.From 12 h onwards,there was a linear decrease(P<0.05)in carbon dioxide(CO_(2))production with increasing YRI:CRI ratio.At 72 h,the ratios of 50:50 and 75:25 had higher dry matter(+7.71%and+4.11%,respectively),as well as higher acid detergent fiber digestibility(+15.5%and+7.61%,respectively),when compared to the 0:100 ratio(P<0.05).Increasing the proportion of YRI generally increased total VFA concentrations,and,concomitantly,decreased the proportion of metabolic hydrogen([2H])incorporated into CH_(4),and decreased the recovery of[2H].The lower[2H]recovery indicates unknown[2H]sinks in the culture.Estimated Gibbs free energy changes(ΔG)for reductive acetogenesis were negative,indicating the thermodynamic feasibility of this process.It would be beneficial to identify:1)the alternative[2H]sinks,which could help mitigate CH_(4)emission,and 2)core microbes involved in fiber digestion.This experiment supported lower CH_(4)emission and greater nutrient digestibility of yaks compared to cattle.Multi-omics combined with microbial culture technologies developed in recent years could help to better understand fermentation differences among species.展开更多
Considerable levels of methylmercury(MeHg)have been found rice-based infant cereals as a result of MeHg transfer from the rice as a raw material to the products,hence consumption of rice products may pose a potential ...Considerable levels of methylmercury(MeHg)have been found rice-based infant cereals as a result of MeHg transfer from the rice as a raw material to the products,hence consumption of rice products may pose a potential health risk to infants who may receive cereals as the major diets and are susceptible to toxicity of MeHg.Determination of bioaccessibility of MeHg would provide a more accurate assessment of MeHg exposure through consumption of rice-based cereals,yet this information remains lacking.Further,the re-adsorption of methylmercury on the residual food will affect the accurate assessment of its bioaccessibility.Our goals in this work were 1)to determine the bioaccessibility of MeHg in infant rice cereals commonly available on the market by using a typical in vitro artificial gastrointestinal digestionmodel and 2)to evaluate the effects of MeHg re-adsorption on the in vitro assessment of MeHg bioaccessibility.The determined bioaccessibility of MeHg in the studied rice cereals after the standard dual-step(using gastric followed by intestinal juice)protocol ranged from 25%to 74%,a wide range comparable to that of fish samples observed here and in previous studies.The surprisingly higher bioaccessibility of MeHg in fish and rice cereals after the gastric step only,in comparison to after the complete two-step gastrointestinal digestion,suggests the re-adsorption of MeHg on the residual food.Separate experiments with spiked MeHg standards confirmed that the MeHg released by the acetic gastric juice was re-adsorbed on the residues during the intestinal step at neutral pH.This study provided first-hand data on the bioaccessibility of MeHg in infant rice cereals and methodological implications on using in vitro digestion to evaluate the bioaccessibility of MeHg and metal contaminants in general.展开更多
Milk fat globules(MFG)are the primary source of energy and functional factor in dairy-based products.To evaluate the suitability of commercial MFG substitutes for infant and adult consumers,the lipolysis properties an...Milk fat globules(MFG)are the primary source of energy and functional factor in dairy-based products.To evaluate the suitability of commercial MFG substitutes for infant and adult consumers,the lipolysis properties and regulatory factors in digesting bovine,caprine,and human MFG were compared.The lipolysis kinetic models of bovine and caprine MFG are comparable,with bovine MFG displaying the highest degree of lipolysis(50.21%)during gastric digestion in infants,resulting in the production short-chain saturated fatty acids.Caprine MFG has a high rate of lipolysis due to its weak phospholipid-glycoprotein layer,which is prominent in both infants'and adults'digestion.The effects of consuming bovine and caprine MFG for adults are comparable in terms of lipolysis properties and nutritional value of fatty acid.After gastrointestinal digestion,human MFG has the highest digestibility(93.98%).The advantages of human MFG include its phospholipid structure,exogenous lipase,and lipolysis-regulating proteins.This study provides recommendation for the selection of milk fat substitutes and improvements in commercial dairy.展开更多
Temperature plays a crucial role in shaping microbial ecosystems during anaerobic digestion.However,the specific microbial communities and their functions across a wide temperature range still remain elusive.This stud...Temperature plays a crucial role in shaping microbial ecosystems during anaerobic digestion.However,the specific microbial communities and their functions across a wide temperature range still remain elusive.This study employed a genome-centric metagenomic approach to explore microbial metabolic pathways and synergistic networks at temperatures of 35,44,53,55,and 65℃.A total of 84 metagenome assembled genomes(MAGs)were assembled,with over 65%of these MAGs corresponding to novel bacterial and archaeal species(including Firmicutes,Chloroflexota,Bacteroidia and Methanobacteriota),greatly enhancing our current comprehension anaerobic digestion process.Notably,functional annotation identified that 44_bin.2(Methanothrix_A sp.001602645)harbors enzymes associated with hydrogenotrophic metabolism.Additionally,this microorganism exhibited diverse metabolic capabilities at 44℃,a temperature commonly employed in industrial practice yet less explored in bench studies.Consequently,it implies a promising potential for conducting anaerobic digestion at a moderate thermophilic temperature,as opposed to the conventional mesophilic range.The microorganism exhibited a variety of metabolic capabilities at 44℃,a temperature frequently employed in industrial applications but underexplored in laboratory investigations.The findings suggest that anaerobic digestion carried out at moderate thermophilic temperatures may have a higher potential for methane production.展开更多
Anaerobic digestion(AD)is widely employed for sludge stabilization and waste reduction.However,the slow hydrolysis process hinders methane production and leads to prolonged sludge issues.In this study,an efficient and...Anaerobic digestion(AD)is widely employed for sludge stabilization and waste reduction.However,the slow hydrolysis process hinders methane production and leads to prolonged sludge issues.In this study,an efficient and eco-friendly lysozyme pre-treatment method was utilized to address these challenges.By optimizing lysozyme dosage,hydrolysis and cell lysis were maximized.Furthermore,lysozyme combined with hydrothermal pretreatment enhanced overall efficiency.Results indicate that:(1)When lysozyme dosage reached 90 mg/g TS after 240 min of pretreatment,SCOD,soluble polysaccharides,and protein content reached their maxima at 855.00,44.09,and 204.86 mg/L,respectively.This represented an increase of 85.87%,365.58%,and 259.21%compared to the untreated sludge.Threedimensional fluorescence spectroscopy revealed the highest fluorescence intensity in the IV region(soluble microbial product),promoting microbial metabolic activity.(2)Lysozyme combined with hydrothermal pretreatment significantly increased SCOD,soluble proteins,and polysaccharide release from sludge,reducing SCOD release time.Orthogonal experiments identified Group 3 as the most effective for SCOD and soluble polysaccharide release,while Group 9 released the most soluble proteins.The significance order of factors influencing SCOD,soluble proteins,and polysaccharide release is hydrothermal temperature>hydrothermal time>enzymatic digestion time.(3)The lysozyme-assisted hydrothermal pretreatment group exhibited the fastest release and the highest SCOD concentration of 8,135.00 mg/L during anaerobic digestion.Maximum SCOD consumption and cumulative gas production increased by 95.89%and 130.58%,respectively,compared to the control group,allowing gas production to conclude 3 days earlier.展开更多
Sewage sludge in cities of Yangzi River Belt,China,generally exhibits a lower organic content and higher silt contentdue to leakage of drainage system,which caused low bioenergy recovery and carbon emission benefits i...Sewage sludge in cities of Yangzi River Belt,China,generally exhibits a lower organic content and higher silt contentdue to leakage of drainage system,which caused low bioenergy recovery and carbon emission benefits in conventional anaerobic digestion(CAD).Therefore,this paper is on a pilot scale,a bio-thermophilic pretreatment anaerobic digestion(BTPAD)for low organic sludge(volatile solids(VS)of 4%)was operated with a long-term continuous flow of 200 days.The VS degradation rate and CH_(4) yield of BTPAD increased by 19.93%and 53.33%,respectively,compared to those of CAD.The analysis of organic compositions in sludge revealed that BTPAD mainly improved the hydrolysis of proteins in sludge.Further analysis of microbial community proportions by high-throughput sequencing revealed that the short-term bio-thermophilic pretreatment was enriched in Clostridiales,Coprothermobacter and Gelria,was capable of hydrolyzing acidified proteins,and provided more volatile fatty acid(VFA)for the subsequent reaction.Biome combined with fluorescence quantitative polymerase chain reaction(PCR)analysis showed that the number of bacteria with high methanogenic capacity in BTPAD was much higher than that in CAD during the medium temperature digestion stage,indicating that short-term bio-thermophilic pretreatment could provide better methanogenic conditions for BTPAD.Furthermore,the greenhouse gas emission footprint analysis showed that short-term bio-thermophilic pretreatment could reduce the carbon emission of sludge anaerobic digestion system by 19.18%.展开更多
Whole-grain foods have attracted emerging attention due to their health benefits.Whole grains are rich in bound polyphenols(BPs)linked with dietary fibers,which is largely underestimated compared with free polyphenols...Whole-grain foods have attracted emerging attention due to their health benefits.Whole grains are rich in bound polyphenols(BPs)linked with dietary fibers,which is largely underestimated compared with free polyphenols.In this study,in vitro simulated gastrointestinal digestion and colonic fermentation models were used to study the release profile and metabolism of BPs of oat bran.Significantly higher level of BPs was released during in vitro colon fermentation(3.05 mg GAE/g)than in gastrointestinal digestion(0.54 mg GAE/g).Five polyphenols were detected via LC-MS and their possible conversion pathways were speculated.Released BPs exhibited chemical antioxidant capacity.16S rRNA sequencing further revealed that Clostridium butyricum,Enterococcus faecalis,Bacteroides acidifaciens were the key bacteria involved in the release of BPs,and this was verified by whole-cell transformation.Our results helped to explain the possible mechanism of the health benefits of BPs in whole grains.展开更多
Approximately 99%of micro(nano)plastics in wastewater are retained in waste activated sludge,inhibiting anaerobic digestion,while their specific effects on functional microbes remain unclear.To break through the limit...Approximately 99%of micro(nano)plastics in wastewater are retained in waste activated sludge,inhibiting anaerobic digestion,while their specific effects on functional microbes remain unclear.To break through the limitations of current knowledge,in this review,we focused on summarizing the impacts of micro(nano)plastics on the microbial communities within anaerobic digestion systems,analyzing the toxicity mechanisms and developing strategies to mitigate their inhibitory effects.Firstly,the impacts of micro(nano)plastics on methane production and functional microbes were summarized,including direct cell pitting effects,inhibition caused by toxic leachates,and the adsorption of pollutants onto micro(nano)plastics surfaces,which further interfere with microbial activity and metabolic processes.Then,the specific performances and potential mechanisms by which micro(nano)plastics affect microbes were innovatively analyzed from the aspects of community variation,cellular activity and genetic expression.Moreover,various factors of micro(nano)plastics were found to influence their effects on microbes,including hormesis-like effects at different dosages,increased toxicity with decreasing particle size,enhanced biotoxicity due to surface functional groups,and variations in toxicity based on morphology and aggregation state.Furthermore,potential mitigation strategies,including activated carbon addition,thermal hydrolysis and cationic polyacrylamide application,were firstly summarized in here to alleviate inhibition on microbe.Finally,the current challenges and future directions were fully discussed and prospected.These insights could not only elucidate the biotoxic effects of micro(nano)plastics,but also provide a new avenue for helping to develop effective remediation techniques in micro(nano)plastic pollution management.展开更多
Anaerobic digestion(AD),as an eco-friendly biological process,shows potential for the decomposition of leachate produced by waste incineration power plants.In this study,the effects of Fe oxides nano-modified pumice(F...Anaerobic digestion(AD),as an eco-friendly biological process,shows potential for the decomposition of leachate produced by waste incineration power plants.In this study,the effects of Fe oxides nano-modified pumice(FNP)were investigated on the fresh leachate AD process.Firstly,a simple hydrothermal method was used to prepare FNP,then introduced into the UASB reactor to evaluate its AD efficiency.Results showed that the inclusion of FNP could shorten the lag phase by 10 days compared to the control group.Furthermore,cumulative methane production in the FNP group was enhanced by 20.11%.Mechanistic studies suggested that hydrogenotrophic methanogenesis in the FNP group was more pronounced due to the influence of key enzymes(i.e.,dehydrogenase and coenzyme F420).Microbial community analysis demonstrated that FNP could enhance the abundance of Methanosarcina,Proteobacteria,Sytrophomonas,and Limnobacter,which might elevate enzyme activity involved in methane production.These findings suggest that FNP might mediate interspecies electron transfer among these microorganisms,which is essential for efficient leachate treatment.展开更多
Background Cetobacterium somerae,a symbiotic microorganism resident in various fish intestines,is recognized for its beneficial effects on fish gut health.However,the mechanisms underlying the effects of C.somerae on ...Background Cetobacterium somerae,a symbiotic microorganism resident in various fish intestines,is recognized for its beneficial effects on fish gut health.However,the mechanisms underlying the effects of C.somerae on gut health remain unclear.In this experiment,we investigated the influence of C.somerae(CGMCC No.28843)on the growth performance,intestinal digestive and absorptive capacity,and intestinal structural integrity of juvenile grass carp(Ctenopharyngodon idella)and explored its potential mechanisms.Methods A cohort of 2,160 juvenile grass carp with an initial mean body weight of 11.30±0.01 g were randomly allocated into 6 treatment groups,each comprising 6 replicates(60 fish per replicate).The experimental diets were supplemented with C.somerae at graded levels of 0.00(control),0.68×10^(9),1.35×10^(9),2.04×10^(9),2.70×10^(9),and 3.40×10^(9)cells/kg feed.Following a 10-week experimental period,biological samples were collected for subsequent analyses.Results Dietary supplementation with C.somerae at 1.35×10^(9)cells/kg significantly enhanced growth performance,intestinal development,and nutrient retention rate in juvenile grass carp(P<0.05).The treatment resulted in increased intestinal acetic acid concentration and enhanced activities of digestive enzymes and brush border enzymes(P<0.05).Furthermore,it reduced intestinal permeability(P<0.05),preserved tight junctions(TJ)ultrastructural integrity,and increased the expression of TJ and adherens junctions(AJ)biomarkers at both protein and transcriptional levels(P<0.05).Mechanistically,these effects may be correlated with enhanced antioxidant capacity and coordinated modulation of the RhoA/ROCK,Sirt1,and PI3K/AKT signaling pathways.The appropriate supplementation levels,based on weight gain rate,feed conversion ratio,the activity of serum diamine oxidase and the content of lipopolysaccharide,were 1.27×10^(9),1.27×10^(9),1.34×10^(9)and 1.34×10^(9)cells/kg,respectively.Conclusions C.somerae improved intestinal digestive and absorptive capacity of juvenile grass carp,maintained intestinal structural integrity,and thus promoted their growth and development.This work demonstrates the potential of C.somerae as a probiotic for aquatic animals and provides a theoretical basis for its utilization in aquaculture.展开更多
As global populations grow, the generation of various waste materials like fats, oils, and grease (FOG), fruit waste, and other perishable wastes increases concurrently. Disposal of these highly putrescible waste prod...As global populations grow, the generation of various waste materials like fats, oils, and grease (FOG), fruit waste, and other perishable wastes increases concurrently. Disposal of these highly putrescible waste products in landfills consumes valuable landfill space. Anaerobic digestion can transform these waste materials into valuable components, including fertilizer and biogas, reducing the demand for landfill space. The current study is based on the hypothesis that incorporating high-strength organic waste into conventional wastewater sludge can enhance the production of onsite biogas at wastewater treatment plants, therefore contributing to the reduction of the plant’s energy demands from the grid. The batch anaerobic biodegradability test assays were performed for 63 days to observe the impact on the biomethane yield from adding high-strength organic waste to the wastewater sludge and to investigate the combined effects of co-digesting two different preselected high-strength organic waste streams. Additionally, physicochemical characterization was performed on different fruit waste juicing residuals to indicate which fruit wastes might increase anaerobic digestion efficiency. The highest methane yield of 243 mL/gVS and 280 mL/gVS, respectively, were obtained with two mixtures having 10% FOG as the sole substrate and 10% FOG along with 10% fruit waste. The study also assessed the siloxane concentrations present as trace contaminants in the biogas samples. An initial economic feasibility assessment of food waste co-digestion at two wastewater treatment plants in Florida was conducted using the Co-Digestion Economic Analysis Tool (CoEAT) model. Based on the laboratory results, the analysis indicated a net positive benefit of $39,472 for a medium-sized plant (10 - 30 MGD capacity) and $52,488 for a larger plant (>30 MGD capacity) after 15 years, while diverting 10 - 18 tons/day of food waste from landfills with an anticipated minimal increase in sludge volume production at food waste additions less than 10% of the digester feed as stated in the literature.展开更多
Digesting aluminum-bearing minerals and converting ferric oxide to magnetite simultaneously in Bayer digestion process is crucially important to deal with high-iron diasporic bauxite economically for alumina productio...Digesting aluminum-bearing minerals and converting ferric oxide to magnetite simultaneously in Bayer digestion process is crucially important to deal with high-iron diasporic bauxite economically for alumina production.The reaction behaviors of hydrothermal reduction of ferric oxide in alkali solution were studied by both thermodynamic calculation and experimental investigation.The thermodynamic calculation indicates that Fe3O4 can be formed by the conversion of Fe2O3 at proper redox potentials in alkaline solution.The experimental results show that the formation ratio of Fe3O4 either through the reaction of Fe and Fe2O3 or through the reaction of Fe and H2O in alkaline aqueous solution increases remarkably with raising the temperature and alkali concentration,suggesting that Fe（OH）3- and Fe（OH）4- form by dissolving Fe and Fe2O3,respectively,in alkaline aqueous solution and further react to form Fe3O4.Moreover,aluminate ions have little influence on the hydrothermal reduction of Fe2O3 in alkaline aqueous solution,and converting iron minerals to magnetite can be realized in the Bayer digestion process of diasporic bauxite.展开更多
[Objective] The aim was to develop a rapid, simple method for determina- tion of arsenic and mercury in soil samples by atomic fluorescence spectrometry. [Method] The method for determination of As and Hg in soil by c...[Objective] The aim was to develop a rapid, simple method for determina- tion of arsenic and mercury in soil samples by atomic fluorescence spectrometry. [Method] The method for determination of As and Hg in soil by combined atomic fluorescence spectrometry and microwave digestion was used. [Result] The concentration curve was linear within the range of 0-80.0μg/L of As and 0-8.0 μg/L of Hg, and the detection limits of As and Hg was 0.036 μg/L and 0.015 μg/L, respectively. The precision for elevenfold determination of As at 40.0 ug/L level and Hg at 4.0μg/L level were 1.1% and 2.2%（RSD）, respectively. Recoveries of 103.0%-106.6% for As and 90.0%-95.0% for Hg were obtained for there soil samples. [Conclusion] The proposed method has the advantages of simple operation, high sensitivity, and high efficiency; it was successfully used for determination of As and Hg in soil samples.展开更多
[Objective] The aim was to develop a rapid, simple method for determination of chromium and zinc in soil samples by flame atomic absorption spectrometry.[Method] The method for determination of Cr and Zn in soil by co...[Objective] The aim was to develop a rapid, simple method for determination of chromium and zinc in soil samples by flame atomic absorption spectrometry.[Method] The method for determination of Cr and Zn in soil by combined flame atomic absorption spectrometry and microwave digestion was used. [Result] The concentration curve was linear within the range of 0-0.8 mg/L for Cr and 0-0.8 mg/L for Zn, the detection limits of Cr and Zn was 0.0025 mg/L and 0.002 3 mg/L, respectively. Recoveries of 102.4%-103.2% for Cr and 97.7%-98.3% for Zn were obtained for there soil samples. [Conclusion] The proposed method has the advantages of simple operation, high sensitivity, and high efficiency; it was successfully used for determination of Cr and Zn in soil samples.展开更多
In the research, pot experiment and field testing were conducted to study the effect of different crops, soil types, and irrigation modes on biogas slurry diges- tions. The results showed that when silage maize, sweet...In the research, pot experiment and field testing were conducted to study the effect of different crops, soil types, and irrigation modes on biogas slurry diges- tions. The results showed that when silage maize, sweet sorghum and Chinese cabbage were planted in purple soils, the quantities of digested biogas slurry were of 57, 157.5, and 34.5 t/hm2, respectively, while the quantities of digested biogas slurry were 70.5, 157.5 and 40.5 t/hm2 in yellow soils. Besides, the digested biogas slurries reached 36 and 27 t/hm2 as per flood irrigation and sprinkling irrigation when Chinese cabbages were planted in yellow soils. The research indicated crop variety, soil type, and irrigation method all have effects on farmland digestion of biogas slurry.展开更多
To obtain the appropriate conditions for eliminating Fe3＋from NiSO4 solution, the digestion solution of the clinker was used as raw material, which was obtained from roasting the nickel oxide ore with （NH4）2SO4. Th...To obtain the appropriate conditions for eliminating Fe3＋from NiSO4 solution, the digestion solution of the clinker was used as raw material, which was obtained from roasting the nickel oxide ore with （NH4）2SO4. The ammonium jarosite was successfully synthesized from the solution with analytic grade NH4HCO3. The effects of reaction temperature, reaction time, end pH value of reaction on the removal rate of iron were investigated, and the effect of the initial concentration of Fe3＋was also discussed. All of those factors had significant effects on the removal rate of Fe3＋, among which the reaction temperature was the most prominent. The appropriate reaction conditions were concluded as follows： reaction temperature 95 ℃ reaction time 3.5 h, end pH value of reaction 2.5 at initial concentration of Fe3＋19.36 g/L. The physical aspect of （NH4）2Fe6（SO4）4（OH）12 was cluster figure composed of sheet or prismatic particles with smooth surface.展开更多
[Objective] The aim was to study on effect of sludge from different sources on biogas yield efficiency through anaerobic digestion of corn straw. [Method] The present research studied on daily biogas yield and the acc...[Objective] The aim was to study on effect of sludge from different sources on biogas yield efficiency through anaerobic digestion of corn straw. [Method] The present research studied on daily biogas yield and the accumulated biogas amount through anaerobic digestion of corn straw and sludges from four sources. [Result] The accumulated biogas yields produced from sludges in four sources from high to low were granular sludge, river sediments, concentrated sludge and filtered sludge. The first one proved the highest at 3.73 and 56.29 L/kg VS in daily biogas yield and the accumulated biogas. [Conclusion] The research laid foundation for full utilization of straw, improvement of energy utilization and sustainable development.展开更多
Two-phase anaerobic digestion process is influenced by acid control for hydrogen production, reaction temperature, substrate detention time, sludge activity, and granular formation. Al of these technological parameter...Two-phase anaerobic digestion process is influenced by acid control for hydrogen production, reaction temperature, substrate detention time, sludge activity, and granular formation. Al of these technological parameters are directly related to success or failure of the system operation and treatment effect.展开更多
Alkaline and ultrasonic sludge disintegration can be used as the pretreatment of waste activated sludge （WAS） to promote the subsequent anaerobic or aerobic digestion. In this study, different combinations of these ...Alkaline and ultrasonic sludge disintegration can be used as the pretreatment of waste activated sludge （WAS） to promote the subsequent anaerobic or aerobic digestion. In this study, different combinations of these two methods were investigated. The evaluation was based on the quantity of soluble chemical oxygen demand （SCOD） in the pretreated sludge as well as the degradation of organic matter in the subsequent aerobic digestion. For WAS samples with combined pretreatment, the released COD levels were higher than those with ultrasonic or alkaline pretreatment alone. When combined with the ultrasonic treatment, NaOH treatment was more efficient than Ca（OH）2 for WAS solubilization. The COD levels released in various sequential options of combined NaOH and ultrasonic treatments were in the the following descending order： simultaneous treatment 〉 NaOH treatment followed by ultrasonic treatment 〉 ultrasonic treatment followed by NaOH treatment. For simultaneous treatment, low NaOH dosage （100 g/kg dry solid）, short duration （30 min） of NaOH treatment, and low ultrasonic specific energy （7500 kJ/kg dry solid） were suitable for sludge disintegration. Using combined NaOH and ultrasonic pretreatment with optimal parameters, the degradation efficiency of organic matter was increased from 38.0% to 50.7%, which is much higher than that with ultrasonic （42.5%） or with NaOH pretreatment （43.5%） in the subsequent aerobic digestion at the same retention time.展开更多
基金the financial support from the Natural Science Foundation of Hunan Province,China(No.2022JJ40616)。
文摘The differences in the competitive reactions of hydrogarnet and quicklime when reacting with titaniumcontaining and silicon-containing minerals during the Bayer digestion process were investigated.Thermodynamic analysis,artificial mineral experiments,and an evaluation of the digestion effect of natural diasporic bauxite were conducted.The results indicate that hydrogarnet shows a preferential reaction with anatase,and this preference becomes more pronounced as the silicon saturation coefficient increases.In contrast,quicklime participates in non-selective reactions with both anatase and desilication products(DSP).The preference of hydrogarnet for anatase significantly enhances the utilization efficiency of CaO in the high-temperature Bayer digestion process.
基金supported by the National Natural Science Foundation of China(32072757 and U21A20250)。
文摘Yaks are well-adapted to the harsh environment of the Tibetan Plateau,and they emit less enteric methane(CH_(4))and digest poor-quality forage better than cattle.To examine the potential of yak rumen inoculum to mitigate CH_(4)production and improve digestibility in cattle,we incubated substrate with rumen inoculum from yak(YRI)and cattle(CRI)in vitro in five ratios(YRI:CRI):(1)0:100(control),(2)25:75,(3)50:50,(4)75:25 and(5)100:0 for 72 h.The YRI:CRI ratios of 50:50,75:25 and 100:0 produced less total gas and CH_(4)and accumulated less hydrogen(H_(2))than0:100(control)at most time points.From 12 h onwards,there was a linear decrease(P<0.05)in carbon dioxide(CO_(2))production with increasing YRI:CRI ratio.At 72 h,the ratios of 50:50 and 75:25 had higher dry matter(+7.71%and+4.11%,respectively),as well as higher acid detergent fiber digestibility(+15.5%and+7.61%,respectively),when compared to the 0:100 ratio(P<0.05).Increasing the proportion of YRI generally increased total VFA concentrations,and,concomitantly,decreased the proportion of metabolic hydrogen([2H])incorporated into CH_(4),and decreased the recovery of[2H].The lower[2H]recovery indicates unknown[2H]sinks in the culture.Estimated Gibbs free energy changes(ΔG)for reductive acetogenesis were negative,indicating the thermodynamic feasibility of this process.It would be beneficial to identify:1)the alternative[2H]sinks,which could help mitigate CH_(4)emission,and 2)core microbes involved in fiber digestion.This experiment supported lower CH_(4)emission and greater nutrient digestibility of yaks compared to cattle.Multi-omics combined with microbial culture technologies developed in recent years could help to better understand fermentation differences among species.
基金supported by the National Natural Science Foundation of China(No.22306111)Shandong Provincial Natural Science Foundation of China(Nos.ZR2022QB242 and ZR2020ZD20).
文摘Considerable levels of methylmercury(MeHg)have been found rice-based infant cereals as a result of MeHg transfer from the rice as a raw material to the products,hence consumption of rice products may pose a potential health risk to infants who may receive cereals as the major diets and are susceptible to toxicity of MeHg.Determination of bioaccessibility of MeHg would provide a more accurate assessment of MeHg exposure through consumption of rice-based cereals,yet this information remains lacking.Further,the re-adsorption of methylmercury on the residual food will affect the accurate assessment of its bioaccessibility.Our goals in this work were 1)to determine the bioaccessibility of MeHg in infant rice cereals commonly available on the market by using a typical in vitro artificial gastrointestinal digestionmodel and 2)to evaluate the effects of MeHg re-adsorption on the in vitro assessment of MeHg bioaccessibility.The determined bioaccessibility of MeHg in the studied rice cereals after the standard dual-step(using gastric followed by intestinal juice)protocol ranged from 25%to 74%,a wide range comparable to that of fish samples observed here and in previous studies.The surprisingly higher bioaccessibility of MeHg in fish and rice cereals after the gastric step only,in comparison to after the complete two-step gastrointestinal digestion,suggests the re-adsorption of MeHg on the residual food.Separate experiments with spiked MeHg standards confirmed that the MeHg released by the acetic gastric juice was re-adsorbed on the residues during the intestinal step at neutral pH.This study provided first-hand data on the bioaccessibility of MeHg in infant rice cereals and methodological implications on using in vitro digestion to evaluate the bioaccessibility of MeHg and metal contaminants in general.
基金supported by the Young Scientists Fund in National Natural Science Foundation of China(31901650)Ministry of Science and Technology of the People’s Republic of China(2016YFD0401404)Innovation Fund of Tianjin University of Science and Technology for Young Teachers(2017LG01)。
文摘Milk fat globules(MFG)are the primary source of energy and functional factor in dairy-based products.To evaluate the suitability of commercial MFG substitutes for infant and adult consumers,the lipolysis properties and regulatory factors in digesting bovine,caprine,and human MFG were compared.The lipolysis kinetic models of bovine and caprine MFG are comparable,with bovine MFG displaying the highest degree of lipolysis(50.21%)during gastric digestion in infants,resulting in the production short-chain saturated fatty acids.Caprine MFG has a high rate of lipolysis due to its weak phospholipid-glycoprotein layer,which is prominent in both infants'and adults'digestion.The effects of consuming bovine and caprine MFG for adults are comparable in terms of lipolysis properties and nutritional value of fatty acid.After gastrointestinal digestion,human MFG has the highest digestibility(93.98%).The advantages of human MFG include its phospholipid structure,exogenous lipase,and lipolysis-regulating proteins.This study provides recommendation for the selection of milk fat substitutes and improvements in commercial dairy.
基金supported by the National Natural Science Foundation of China(No.52270138)。
文摘Temperature plays a crucial role in shaping microbial ecosystems during anaerobic digestion.However,the specific microbial communities and their functions across a wide temperature range still remain elusive.This study employed a genome-centric metagenomic approach to explore microbial metabolic pathways and synergistic networks at temperatures of 35,44,53,55,and 65℃.A total of 84 metagenome assembled genomes(MAGs)were assembled,with over 65%of these MAGs corresponding to novel bacterial and archaeal species(including Firmicutes,Chloroflexota,Bacteroidia and Methanobacteriota),greatly enhancing our current comprehension anaerobic digestion process.Notably,functional annotation identified that 44_bin.2(Methanothrix_A sp.001602645)harbors enzymes associated with hydrogenotrophic metabolism.Additionally,this microorganism exhibited diverse metabolic capabilities at 44℃,a temperature commonly employed in industrial practice yet less explored in bench studies.Consequently,it implies a promising potential for conducting anaerobic digestion at a moderate thermophilic temperature,as opposed to the conventional mesophilic range.The microorganism exhibited a variety of metabolic capabilities at 44℃,a temperature frequently employed in industrial applications but underexplored in laboratory investigations.The findings suggest that anaerobic digestion carried out at moderate thermophilic temperatures may have a higher potential for methane production.
文摘Anaerobic digestion(AD)is widely employed for sludge stabilization and waste reduction.However,the slow hydrolysis process hinders methane production and leads to prolonged sludge issues.In this study,an efficient and eco-friendly lysozyme pre-treatment method was utilized to address these challenges.By optimizing lysozyme dosage,hydrolysis and cell lysis were maximized.Furthermore,lysozyme combined with hydrothermal pretreatment enhanced overall efficiency.Results indicate that:(1)When lysozyme dosage reached 90 mg/g TS after 240 min of pretreatment,SCOD,soluble polysaccharides,and protein content reached their maxima at 855.00,44.09,and 204.86 mg/L,respectively.This represented an increase of 85.87%,365.58%,and 259.21%compared to the untreated sludge.Threedimensional fluorescence spectroscopy revealed the highest fluorescence intensity in the IV region(soluble microbial product),promoting microbial metabolic activity.(2)Lysozyme combined with hydrothermal pretreatment significantly increased SCOD,soluble proteins,and polysaccharide release from sludge,reducing SCOD release time.Orthogonal experiments identified Group 3 as the most effective for SCOD and soluble polysaccharide release,while Group 9 released the most soluble proteins.The significance order of factors influencing SCOD,soluble proteins,and polysaccharide release is hydrothermal temperature>hydrothermal time>enzymatic digestion time.(3)The lysozyme-assisted hydrothermal pretreatment group exhibited the fastest release and the highest SCOD concentration of 8,135.00 mg/L during anaerobic digestion.Maximum SCOD consumption and cumulative gas production increased by 95.89%and 130.58%,respectively,compared to the control group,allowing gas production to conclude 3 days earlier.
基金supported by the National Key Research and Development Project (Nos.2020YFC1908702 and 2021YFC3200700)the National Natural Science Foundation of China (Nos.52192684 and 52192680).
文摘Sewage sludge in cities of Yangzi River Belt,China,generally exhibits a lower organic content and higher silt contentdue to leakage of drainage system,which caused low bioenergy recovery and carbon emission benefits in conventional anaerobic digestion(CAD).Therefore,this paper is on a pilot scale,a bio-thermophilic pretreatment anaerobic digestion(BTPAD)for low organic sludge(volatile solids(VS)of 4%)was operated with a long-term continuous flow of 200 days.The VS degradation rate and CH_(4) yield of BTPAD increased by 19.93%and 53.33%,respectively,compared to those of CAD.The analysis of organic compositions in sludge revealed that BTPAD mainly improved the hydrolysis of proteins in sludge.Further analysis of microbial community proportions by high-throughput sequencing revealed that the short-term bio-thermophilic pretreatment was enriched in Clostridiales,Coprothermobacter and Gelria,was capable of hydrolyzing acidified proteins,and provided more volatile fatty acid(VFA)for the subsequent reaction.Biome combined with fluorescence quantitative polymerase chain reaction(PCR)analysis showed that the number of bacteria with high methanogenic capacity in BTPAD was much higher than that in CAD during the medium temperature digestion stage,indicating that short-term bio-thermophilic pretreatment could provide better methanogenic conditions for BTPAD.Furthermore,the greenhouse gas emission footprint analysis showed that short-term bio-thermophilic pretreatment could reduce the carbon emission of sludge anaerobic digestion system by 19.18%.
基金the support from the research grants by National Natural Science Foundation of China(32202051)National Key R&D Program of China(2022YFF1100104)the Major Project of Inner Mongolia Science and Technology Department,China(2021ZD0002)。
文摘Whole-grain foods have attracted emerging attention due to their health benefits.Whole grains are rich in bound polyphenols(BPs)linked with dietary fibers,which is largely underestimated compared with free polyphenols.In this study,in vitro simulated gastrointestinal digestion and colonic fermentation models were used to study the release profile and metabolism of BPs of oat bran.Significantly higher level of BPs was released during in vitro colon fermentation(3.05 mg GAE/g)than in gastrointestinal digestion(0.54 mg GAE/g).Five polyphenols were detected via LC-MS and their possible conversion pathways were speculated.Released BPs exhibited chemical antioxidant capacity.16S rRNA sequencing further revealed that Clostridium butyricum,Enterococcus faecalis,Bacteroides acidifaciens were the key bacteria involved in the release of BPs,and this was verified by whole-cell transformation.Our results helped to explain the possible mechanism of the health benefits of BPs in whole grains.
基金financially sponsored by the funding from the National Key Research and Development Program of China(No.2023YFC3207404)the National Nature Science Foundation of China(No.52270034)State Key Laboratory of Urban Water Resource and Environment(No.2023TS16)。
文摘Approximately 99%of micro(nano)plastics in wastewater are retained in waste activated sludge,inhibiting anaerobic digestion,while their specific effects on functional microbes remain unclear.To break through the limitations of current knowledge,in this review,we focused on summarizing the impacts of micro(nano)plastics on the microbial communities within anaerobic digestion systems,analyzing the toxicity mechanisms and developing strategies to mitigate their inhibitory effects.Firstly,the impacts of micro(nano)plastics on methane production and functional microbes were summarized,including direct cell pitting effects,inhibition caused by toxic leachates,and the adsorption of pollutants onto micro(nano)plastics surfaces,which further interfere with microbial activity and metabolic processes.Then,the specific performances and potential mechanisms by which micro(nano)plastics affect microbes were innovatively analyzed from the aspects of community variation,cellular activity and genetic expression.Moreover,various factors of micro(nano)plastics were found to influence their effects on microbes,including hormesis-like effects at different dosages,increased toxicity with decreasing particle size,enhanced biotoxicity due to surface functional groups,and variations in toxicity based on morphology and aggregation state.Furthermore,potential mitigation strategies,including activated carbon addition,thermal hydrolysis and cationic polyacrylamide application,were firstly summarized in here to alleviate inhibition on microbe.Finally,the current challenges and future directions were fully discussed and prospected.These insights could not only elucidate the biotoxic effects of micro(nano)plastics,but also provide a new avenue for helping to develop effective remediation techniques in micro(nano)plastic pollution management.
基金supported by the National Key Research and Development Program of China(No.2019YFC0408500)the Scientific Research Project of China State Construction Engineering Corporation Limited(CSCEC-2022-K-(36))the Scientific Research Project of CSCEC AECOM Consultants Corporation Limited(XBSZKY2216).
文摘Anaerobic digestion(AD),as an eco-friendly biological process,shows potential for the decomposition of leachate produced by waste incineration power plants.In this study,the effects of Fe oxides nano-modified pumice(FNP)were investigated on the fresh leachate AD process.Firstly,a simple hydrothermal method was used to prepare FNP,then introduced into the UASB reactor to evaluate its AD efficiency.Results showed that the inclusion of FNP could shorten the lag phase by 10 days compared to the control group.Furthermore,cumulative methane production in the FNP group was enhanced by 20.11%.Mechanistic studies suggested that hydrogenotrophic methanogenesis in the FNP group was more pronounced due to the influence of key enzymes(i.e.,dehydrogenase and coenzyme F420).Microbial community analysis demonstrated that FNP could enhance the abundance of Methanosarcina,Proteobacteria,Sytrophomonas,and Limnobacter,which might elevate enzyme activity involved in methane production.These findings suggest that FNP might mediate interspecies electron transfer among these microorganisms,which is essential for efficient leachate treatment.
基金financially supported by the earmarked fund for the earmarked fund for CARS(CARS-45)National Science Fund for Distinguished Young Scholars of China(32425056)+1 种基金the National Key R&D Program of China(2023YFD2400600)Sichuan Innovation Team of National Modern Agricultural Industry Technology System(SCCXTD-2024-16).
文摘Background Cetobacterium somerae,a symbiotic microorganism resident in various fish intestines,is recognized for its beneficial effects on fish gut health.However,the mechanisms underlying the effects of C.somerae on gut health remain unclear.In this experiment,we investigated the influence of C.somerae(CGMCC No.28843)on the growth performance,intestinal digestive and absorptive capacity,and intestinal structural integrity of juvenile grass carp(Ctenopharyngodon idella)and explored its potential mechanisms.Methods A cohort of 2,160 juvenile grass carp with an initial mean body weight of 11.30±0.01 g were randomly allocated into 6 treatment groups,each comprising 6 replicates(60 fish per replicate).The experimental diets were supplemented with C.somerae at graded levels of 0.00(control),0.68×10^(9),1.35×10^(9),2.04×10^(9),2.70×10^(9),and 3.40×10^(9)cells/kg feed.Following a 10-week experimental period,biological samples were collected for subsequent analyses.Results Dietary supplementation with C.somerae at 1.35×10^(9)cells/kg significantly enhanced growth performance,intestinal development,and nutrient retention rate in juvenile grass carp(P<0.05).The treatment resulted in increased intestinal acetic acid concentration and enhanced activities of digestive enzymes and brush border enzymes(P<0.05).Furthermore,it reduced intestinal permeability(P<0.05),preserved tight junctions(TJ)ultrastructural integrity,and increased the expression of TJ and adherens junctions(AJ)biomarkers at both protein and transcriptional levels(P<0.05).Mechanistically,these effects may be correlated with enhanced antioxidant capacity and coordinated modulation of the RhoA/ROCK,Sirt1,and PI3K/AKT signaling pathways.The appropriate supplementation levels,based on weight gain rate,feed conversion ratio,the activity of serum diamine oxidase and the content of lipopolysaccharide,were 1.27×10^(9),1.27×10^(9),1.34×10^(9)and 1.34×10^(9)cells/kg,respectively.Conclusions C.somerae improved intestinal digestive and absorptive capacity of juvenile grass carp,maintained intestinal structural integrity,and thus promoted their growth and development.This work demonstrates the potential of C.somerae as a probiotic for aquatic animals and provides a theoretical basis for its utilization in aquaculture.
文摘As global populations grow, the generation of various waste materials like fats, oils, and grease (FOG), fruit waste, and other perishable wastes increases concurrently. Disposal of these highly putrescible waste products in landfills consumes valuable landfill space. Anaerobic digestion can transform these waste materials into valuable components, including fertilizer and biogas, reducing the demand for landfill space. The current study is based on the hypothesis that incorporating high-strength organic waste into conventional wastewater sludge can enhance the production of onsite biogas at wastewater treatment plants, therefore contributing to the reduction of the plant’s energy demands from the grid. The batch anaerobic biodegradability test assays were performed for 63 days to observe the impact on the biomethane yield from adding high-strength organic waste to the wastewater sludge and to investigate the combined effects of co-digesting two different preselected high-strength organic waste streams. Additionally, physicochemical characterization was performed on different fruit waste juicing residuals to indicate which fruit wastes might increase anaerobic digestion efficiency. The highest methane yield of 243 mL/gVS and 280 mL/gVS, respectively, were obtained with two mixtures having 10% FOG as the sole substrate and 10% FOG along with 10% fruit waste. The study also assessed the siloxane concentrations present as trace contaminants in the biogas samples. An initial economic feasibility assessment of food waste co-digestion at two wastewater treatment plants in Florida was conducted using the Co-Digestion Economic Analysis Tool (CoEAT) model. Based on the laboratory results, the analysis indicated a net positive benefit of $39,472 for a medium-sized plant (10 - 30 MGD capacity) and $52,488 for a larger plant (>30 MGD capacity) after 15 years, while diverting 10 - 18 tons/day of food waste from landfills with an anticipated minimal increase in sludge volume production at food waste additions less than 10% of the digester feed as stated in the literature.
基金Project(51374239)supported by the National Natural Science Foundation of China
文摘Digesting aluminum-bearing minerals and converting ferric oxide to magnetite simultaneously in Bayer digestion process is crucially important to deal with high-iron diasporic bauxite economically for alumina production.The reaction behaviors of hydrothermal reduction of ferric oxide in alkali solution were studied by both thermodynamic calculation and experimental investigation.The thermodynamic calculation indicates that Fe3O4 can be formed by the conversion of Fe2O3 at proper redox potentials in alkaline solution.The experimental results show that the formation ratio of Fe3O4 either through the reaction of Fe and Fe2O3 or through the reaction of Fe and H2O in alkaline aqueous solution increases remarkably with raising the temperature and alkali concentration,suggesting that Fe（OH）3- and Fe（OH）4- form by dissolving Fe and Fe2O3,respectively,in alkaline aqueous solution and further react to form Fe3O4.Moreover,aluminate ions have little influence on the hydrothermal reduction of Fe2O3 in alkaline aqueous solution,and converting iron minerals to magnetite can be realized in the Bayer digestion process of diasporic bauxite.
基金Supported by Key Fund of Guangxi Academy of Agricultural Sciences(2013YZ07)~~
文摘[Objective] The aim was to develop a rapid, simple method for determina- tion of arsenic and mercury in soil samples by atomic fluorescence spectrometry. [Method] The method for determination of As and Hg in soil by combined atomic fluorescence spectrometry and microwave digestion was used. [Result] The concentration curve was linear within the range of 0-80.0μg/L of As and 0-8.0 μg/L of Hg, and the detection limits of As and Hg was 0.036 μg/L and 0.015 μg/L, respectively. The precision for elevenfold determination of As at 40.0 ug/L level and Hg at 4.0μg/L level were 1.1% and 2.2%（RSD）, respectively. Recoveries of 103.0%-106.6% for As and 90.0%-95.0% for Hg were obtained for there soil samples. [Conclusion] The proposed method has the advantages of simple operation, high sensitivity, and high efficiency; it was successfully used for determination of As and Hg in soil samples.
基金Supported by Key Fund of Guangxi Academy of Agricultural Sciences(2014JZ01 and2013YZ07)~~
文摘[Objective] The aim was to develop a rapid, simple method for determination of chromium and zinc in soil samples by flame atomic absorption spectrometry.[Method] The method for determination of Cr and Zn in soil by combined flame atomic absorption spectrometry and microwave digestion was used. [Result] The concentration curve was linear within the range of 0-0.8 mg/L for Cr and 0-0.8 mg/L for Zn, the detection limits of Cr and Zn was 0.0025 mg/L and 0.002 3 mg/L, respectively. Recoveries of 102.4%-103.2% for Cr and 97.7%-98.3% for Zn were obtained for there soil samples. [Conclusion] The proposed method has the advantages of simple operation, high sensitivity, and high efficiency; it was successfully used for determination of Cr and Zn in soil samples.
基金Supported by International Science&Technology Cooperation Program of China(2013DFA61260)Sub-project of National Science and Technology Planning in Rural Areas during the 12th Five-year Plan(2011BAD36B01)~~
文摘In the research, pot experiment and field testing were conducted to study the effect of different crops, soil types, and irrigation modes on biogas slurry diges- tions. The results showed that when silage maize, sweet sorghum and Chinese cabbage were planted in purple soils, the quantities of digested biogas slurry were of 57, 157.5, and 34.5 t/hm2, respectively, while the quantities of digested biogas slurry were 70.5, 157.5 and 40.5 t/hm2 in yellow soils. Besides, the digested biogas slurries reached 36 and 27 t/hm2 as per flood irrigation and sprinkling irrigation when Chinese cabbages were planted in yellow soils. The research indicated crop variety, soil type, and irrigation method all have effects on farmland digestion of biogas slurry.
基金Project(51204054)supported by the National Natural Science Foundation of ChinaProject(N110402012)supported by Fundamental Research Funds for the Central Universities,ChinaProject(2007CB613603)supported by the National Basic Research Program of China
文摘To obtain the appropriate conditions for eliminating Fe3＋from NiSO4 solution, the digestion solution of the clinker was used as raw material, which was obtained from roasting the nickel oxide ore with （NH4）2SO4. The ammonium jarosite was successfully synthesized from the solution with analytic grade NH4HCO3. The effects of reaction temperature, reaction time, end pH value of reaction on the removal rate of iron were investigated, and the effect of the initial concentration of Fe3＋was also discussed. All of those factors had significant effects on the removal rate of Fe3＋, among which the reaction temperature was the most prominent. The appropriate reaction conditions were concluded as follows： reaction temperature 95 ℃ reaction time 3.5 h, end pH value of reaction 2.5 at initial concentration of Fe3＋19.36 g/L. The physical aspect of （NH4）2Fe6（SO4）4（OH）12 was cluster figure composed of sheet or prismatic particles with smooth surface.
基金National Basic Research Program of China (973 Program) (2009CB724700,2011CBA00800)National Natural Foundation of China (31101269)+4 种基金Scienc & Technology Plotform Construction Programof Jiangxi Province (2010DTZ01900)A Project Funded by the Priority Academic Program Development of Jiangsu Higher Education InstitutionsNatural Science Foundation of Jiangsu Department of Education (07KJD350034)High-level Talents Foundation of Jiangsu University (07JDG020)Supported by International Foundation for Science (F 4930-1)~~
文摘[Objective] The aim was to study on effect of sludge from different sources on biogas yield efficiency through anaerobic digestion of corn straw. [Method] The present research studied on daily biogas yield and the accumulated biogas amount through anaerobic digestion of corn straw and sludges from four sources. [Result] The accumulated biogas yields produced from sludges in four sources from high to low were granular sludge, river sediments, concentrated sludge and filtered sludge. The first one proved the highest at 3.73 and 56.29 L/kg VS in daily biogas yield and the accumulated biogas. [Conclusion] The research laid foundation for full utilization of straw, improvement of energy utilization and sustainable development.
基金Supported by Yunnan S&T Innovation Platform Construction Project(2013DH041)National Natural Science Foundation of China(51366015)Specialized Research Fund for the Doctoral Program of Higher Education of China(20135303110001)~~
文摘Two-phase anaerobic digestion process is influenced by acid control for hydrogen production, reaction temperature, substrate detention time, sludge activity, and granular formation. Al of these technological parameters are directly related to success or failure of the system operation and treatment effect.
基金supported by the China NationalEleventh Five-Year Scientific and Technical Support Plan(No. 2006BAC02A18)
文摘Alkaline and ultrasonic sludge disintegration can be used as the pretreatment of waste activated sludge （WAS） to promote the subsequent anaerobic or aerobic digestion. In this study, different combinations of these two methods were investigated. The evaluation was based on the quantity of soluble chemical oxygen demand （SCOD） in the pretreated sludge as well as the degradation of organic matter in the subsequent aerobic digestion. For WAS samples with combined pretreatment, the released COD levels were higher than those with ultrasonic or alkaline pretreatment alone. When combined with the ultrasonic treatment, NaOH treatment was more efficient than Ca（OH）2 for WAS solubilization. The COD levels released in various sequential options of combined NaOH and ultrasonic treatments were in the the following descending order： simultaneous treatment 〉 NaOH treatment followed by ultrasonic treatment 〉 ultrasonic treatment followed by NaOH treatment. For simultaneous treatment, low NaOH dosage （100 g/kg dry solid）, short duration （30 min） of NaOH treatment, and low ultrasonic specific energy （7500 kJ/kg dry solid） were suitable for sludge disintegration. Using combined NaOH and ultrasonic pretreatment with optimal parameters, the degradation efficiency of organic matter was increased from 38.0% to 50.7%, which is much higher than that with ultrasonic （42.5%） or with NaOH pretreatment （43.5%） in the subsequent aerobic digestion at the same retention time.
