The results of the study on the effect of Cu2+ concentration on hydrogen production using a glucose solution and mixed microorganisms from a 9 2 L laboratory-scale digester operated at 35 ℃ indicated the productions ...The results of the study on the effect of Cu2+ concentration on hydrogen production using a glucose solution and mixed microorganisms from a 9 2 L laboratory-scale digester operated at 35 ℃ indicated the productions of hydrogen, volatile fatty acids （VFAs）, ethanol and biogas were inhibited by the added Cu2+ which caused a reduction in the glucose degradation efficiency. The specific yields of hydrogen, ethanol and acetate decreased with increased Cu2+ concentration in the mixed microorganisms. When the Cu2+ concentration in the mixed microorganisms was almost an constant, the specific yields of hydrogen, ethanol and acetate were very similar. A 50% inhibition of hydrogen yield (EC50) occurred at a Cu2+ dosage of 0 50 mg/L in the present investigation. Cu2+ in the external environment is accumulated in the mixed microorganisms. The Cu2+ speciation, using a sequential extraction technique, showed that the Cu2+ was present mainly bound to organic sites in the mixed microorganisms in the present investigation.展开更多
The hydrolysate of waste sludge was used as the feedstock of biodiesel production,and its technological feasibility was investigated.Waste sludge,collected from No.3 Municipal Wastewater Treatment Plant of Xi’an,was ...The hydrolysate of waste sludge was used as the feedstock of biodiesel production,and its technological feasibility was investigated.Waste sludge,collected from No.3 Municipal Wastewater Treatment Plant of Xi’an,was hydrolyzed in two parallel reactors firstly.Yeast was added into one reactor for bioaugmentation,and the other reactor without yeast was used as a control.Then an acid-catalyzed in situ esterification process was carried out to convert the hydrolysate to biodiesel.The results of hydrolysis showed that the reactor bioaugmented with yeast could promote hydrolysis compared with the control one because of an obvious variance in total suspended solid(TSS),volatile suspended solid(VSS)and soluble chemical oxygen demand(SCOD).Furthermore,gas chromatography(GC)analysis exhibited that the total volatile fatty acid(VFA)was low in the hydrolysate of bioaugmentation reactor;however,its yield of the fatty acid methyl esters(FAMEs)by in situ esterification was obviously higher when compared with the control one.Therefore,it may be inferred that the hydrolysate of bioaugmentation was mainly inclined to longer-chain fatty acid rather than to VFA.Anyway,an FAMEs yield of 9.24%(wt%)from dried sludge was attained after the 12-d bioaugmentation hydrolysis and succedent esterification.This value was not only higher than that of the control one but also higher than that reported in previous literature.The above results illuminated that it was feasible to produce biodiesel from the bioaugmented hydrolysate of waste sludge.展开更多
The concentration of volatile fatty acids （VFA） determined from a previous study was used to determine the concentration of carbon dioxide （CO2） and methane （CH4） in pig digesta using the model developed for rum...The concentration of volatile fatty acids （VFA） determined from a previous study was used to determine the concentration of carbon dioxide （CO2） and methane （CH4） in pig digesta using the model developed for ruminant animals. Digesta from the stomach, cecum and colon of pigs （n = 3 dietl） were used for the determination of VFA. The pigs were fed either a low fiber diet （LFD; 8.3% aNDF） as control, or one of the high-fiber diets （HFD, 22.4% aNDF; D1, D2 and D3） containing 1：2, 1：1 and 2：1, oats to barley ratios, respectively. Results indicated that the concentrations of CO2 and CH4 in pigs fed HFD were, on the average, 25.8 and 24.2%, respectively lower （P 〈 0.05） than pigs fed LFD. Pigs fed the highest oat to barley ratio also showed higher （P 〈 0.05） levels of CO2, （8.3%） and CH4 （5.1%）, compared to the average of the two lower ratios （CO2, 5.3% and CH4, 3.3%）. Molar proportions of VFA, CO2 and CH4 in the gut were in the order of VFA 〉 CO2 〉 CH4, at 53.0%, 28.6% and 18.4%, respectively, and CO2 and CH4 combined represented 47% of total gas.展开更多
Ninety six pigs average weight 9.15 kg were used to study the effects of feeding diets containing multiple sources of dietary fiber （DF） on weight gain and concentration of fermentation products in the digestive tra...Ninety six pigs average weight 9.15 kg were used to study the effects of feeding diets containing multiple sources of dietary fiber （DF） on weight gain and concentration of fermentation products in the digestive tract. The experiment employed four diets and four pens diet1. Diets included a low fiber diet （LFD）, as control and three antibiotic free high-fiber diets （HFD） containing a 1：2, 1：1 or 2：1 oats：barley ratios. At the end of the 70 d feeding trial three pigs of comparable weight diefI were slaughtered. Digesta taken from the stomach, cecum and colon were used for the determination of volatile fatty acids （VFA）. Results indicated that inclusion of HFD increased （P 〈 0.05） feed intake but not weight gain. As revealed by the higher feed intake the nutritional value of HFD was approximately 88% of LFD. Also, as the amount of oats in the diet was increased, VFA concentration was also increased while isobutyrate decreased （P 〈 0.05）. Lower concentration of isobutyrate may indicate parallel reduction in other putatively toxic products of protein fermentation in the digestive tract. Thus, inclusion of multiple sources of fiber in the diet impacted feed intake and the products of gut fermentation in growing pigs.展开更多
The solubility of D-xylose in formic acid and binary solvents of formic acid with formic acid and acetic acid, propionic acid, n-butyric acid or isobutyric acid was measured in the temperature range from 300.35 to 325...The solubility of D-xylose in formic acid and binary solvents of formic acid with formic acid and acetic acid, propionic acid, n-butyric acid or isobutyric acid was measured in the temperature range from 300.35 to 325.05 K using the synthetic method by a laser monitoring technique at atmospheric pressure. The solid-liquid equilibrium data will provide essential support for industrial design and further theoretical study. The experimental data show that the solubility of D-xylose in formic acid and in the mixtures of formic acid + acetic acid(1︰1), formic acid + propionic acid(1︰1), formic acid + n-butyric acid(1︰1), and formic acid + isobutyric acid(1︰1) increases with temperature. The Apelblat equation, the λh model, and the ideal solution equation correlate the solubility data well.展开更多
The study evaluated impact of psychrophilic anaerobic digestion on levels of viable populations of fecal indicator bacteria using various inoculum-to-substrate ratios （I：S）. Laboratory-scale batch reactors were mai...The study evaluated impact of psychrophilic anaerobic digestion on levels of viable populations of fecal indicator bacteria using various inoculum-to-substrate ratios （I：S）. Laboratory-scale batch reactors were maintained at 10 ℃ and 20 ℃ for 25 days with dairy manure substrate. Five treatments included inoculum （control inoculum; inoculum only [CI]）, manure （control manure; substrate only [CM]）, and 3I：1S, II：IS, and 1I：3S. E. coli decreased in all treatments, while Enterococci decreased in only a few treatments. Treatment 1 I： 1S achieved highest E. coli decrease at 20 ℃ （3.11 log）; CM showed highest E. coli decrease at 10 ℃ （2.33 log）. The 1I：3 Streatment showed highest decrease of Enterococci at 20 ℃ （1.82 log）, whereas CM had highest, but less substantial, decrease at 10 ℃ （0.49 log）. These decreases may be the result of environmental conditions, namely substrate limitation for E. coli, and, increased VFA （volatile fatty acid） levels for Enterococci. Lower I：S showed higher levels of indicator organisms; less stable conditions with more acidic pH, higher VFAs, and lower biogas production. Results suggest II：IS is ideal for starting a digester at 20 ℃, whereas 3I：1S appears optimal for 10 ℃, Overall, I：S influenced chemical parameters and fecal indicators during batch psychrophilic anaerobic digestion of manure.展开更多
The aim of this study was to assess the effect of inclusion of fermented apple bagasse （FAB） obtained through solid state fermentation on pH, ammonia nitrogen （N-NH3）, volatile fatty acids （VFA） content, in vitr...The aim of this study was to assess the effect of inclusion of fermented apple bagasse （FAB） obtained through solid state fermentation on pH, ammonia nitrogen （N-NH3）, volatile fatty acids （VFA） content, in vitro dry matter digestibility （IVDMD）, lactic acid and microbial counting of alfalfa hay under in vitro rumen environment; four levels of FAB were evaluated （0, 0.25, 0.50 and 0. 75 g/dry matter of FAB） replacing 1.5 g dry matter （DM） of alfalfa hay and incubated at different fermentation times （0, 4, 8, 12 and 24 h） using a complete random design with repeated measures on time. Counts of live yeast colonies （6.08, 6.33, 6.24 and 6.51 CFU/mL expressed as log 10） was higher when FAB was included in the different levels up to the 12 h of fermentation （P 〈 0.0001）; lactic acid content also increased as FAB was included in the different levels （10.61, 13.86, 16.84 and 14.57μg/mL） up to the 12 h of incubation （P 〈 0.001）. Nevertheless, the other variables measured as pH, N-NH3, VFA, IVDMD, total bacteria and fungi counts, were not affected by the treatments. It is concluded that substitution of FAB by alfalfa hay in an in vitro rumen ecosystem positively modified live yeast colonies and lactic acid concentration, without effect on the other fermentative and microbial parameters of the in vitro rumen environment, but considering mixes of FAB and alfalfa hay as a quality ingredient for the feeding of ruminants.展开更多
This experiment was conducted using by-products from agro-industry as dairy cows feed. Bagasse, pineapple peel, corn cob, corn stover and vinasses were used to produce TMF （total mixed fiber） for dairy cow feed. Fif...This experiment was conducted using by-products from agro-industry as dairy cows feed. Bagasse, pineapple peel, corn cob, corn stover and vinasses were used to produce TMF （total mixed fiber） for dairy cow feed. Fifteen multiparous Holstein Friesian dairy cows with an initial body weight of 417.88± 52.60 kg and 83.31 ± 26.47 DIM （days in milk） were randomly allocated to three treatments （TI = rice straw and 1 kg of vinasses; T2 = SCWS （sweet corn waste silage）; T3 = TMF （total mixed fiber）） under completely randomized design. The results showed that the chemical composition of TMF was in the normal range of pH and VFA （volatile fatty acids） on silage. However, cows fed TMF and SCWS tended to yield higher level of NH3-N. For volatile fatty acid in rumen fluid, acetate in group of cows fed rice straw with vinasse tended to be the highest. Moreover, propionate in cows fed TMF was found to be the highest among all treatments （P 〉 0.05）. In conclusion, the TMF can be used to feed dairy cow without affecting rumen parameter.展开更多
The textile processing plants utilize a wide variety of dyes and other chemicals such as acids, bases, salts, detergents, sizes, oxidants, mercerizing and finishing chemicals. Many of these are not retained in the fin...The textile processing plants utilize a wide variety of dyes and other chemicals such as acids, bases, salts, detergents, sizes, oxidants, mercerizing and finishing chemicals. Many of these are not retained in the final product and are discharged in the effluent. Therefore, the objective of this study was to assess the performance of Expanded Granular Sludge Bed （EGSB） reactor to treat synthetic textile wastewater. Several experiments using Direct Red 81 and volatile fatty acids as model substrates were conducted. The problems of decolorization was evaluated at a variety of relevant operational conditions, such as substrate concentration, organic and hydraulic loading rates. The results showed that retention time of EGSB equals 1.6 h and 80 mg/L at the hydraulic and dye concentration respectively, and that the color removal efficiency can reach 90%. Additionally, some chemical additions were proposed to improve the decolorization rate and increase the treatment efficiency of the system. For instance, sulfide was added at 200 mg/L in the influent, which can increase the dye removal efficiency to 95%.展开更多
The textile processing plants utilize a wide variety of dyes and other chemicals such as acids, bases, salts, detergents, sizes, oxidants, mercerizing and finishing chemicals. Many of these are not retained in the fin...The textile processing plants utilize a wide variety of dyes and other chemicals such as acids, bases, salts, detergents, sizes, oxidants, mercerizing and finishing chemicals. Many of these are not retained in the final product and are discharged in the effluent. Therefore, the objective of this study was to assess the performance of EGSB （Expanded Granular Sludge Bed） reactor to treat non-acidifie wastewater. Several experiments using starch and volatile fatty acids as model substrates were conducted. The problems of piston formation were evaluated at a variety of relevant operational conditions, such as substrate concentration, organic and hydraulic loading rates. The results showed that newly grown acidogenic biomass diluted original methanogenic biomass and the granular sludge in the EGSB reactor deteriorated. The piston formation in the EGSB reactor that was fed with non-acidified wastewater occurred due to high growth of acidogenic biomass and high upflow velocity applied in the system.展开更多
文摘The results of the study on the effect of Cu2+ concentration on hydrogen production using a glucose solution and mixed microorganisms from a 9 2 L laboratory-scale digester operated at 35 ℃ indicated the productions of hydrogen, volatile fatty acids （VFAs）, ethanol and biogas were inhibited by the added Cu2+ which caused a reduction in the glucose degradation efficiency. The specific yields of hydrogen, ethanol and acetate decreased with increased Cu2+ concentration in the mixed microorganisms. When the Cu2+ concentration in the mixed microorganisms was almost an constant, the specific yields of hydrogen, ethanol and acetate were very similar. A 50% inhibition of hydrogen yield (EC50) occurred at a Cu2+ dosage of 0 50 mg/L in the present investigation. Cu2+ in the external environment is accumulated in the mixed microorganisms. The Cu2+ speciation, using a sequential extraction technique, showed that the Cu2+ was present mainly bound to organic sites in the mixed microorganisms in the present investigation.
基金Supported by Excellent Project from Shaanxi Administration of Foreign Expert Affairs in 2011International Cooperation Project of Shaanxi Province(No.2011KW-34)
文摘The hydrolysate of waste sludge was used as the feedstock of biodiesel production,and its technological feasibility was investigated.Waste sludge,collected from No.3 Municipal Wastewater Treatment Plant of Xi’an,was hydrolyzed in two parallel reactors firstly.Yeast was added into one reactor for bioaugmentation,and the other reactor without yeast was used as a control.Then an acid-catalyzed in situ esterification process was carried out to convert the hydrolysate to biodiesel.The results of hydrolysis showed that the reactor bioaugmented with yeast could promote hydrolysis compared with the control one because of an obvious variance in total suspended solid(TSS),volatile suspended solid(VSS)and soluble chemical oxygen demand(SCOD).Furthermore,gas chromatography(GC)analysis exhibited that the total volatile fatty acid(VFA)was low in the hydrolysate of bioaugmentation reactor;however,its yield of the fatty acid methyl esters(FAMEs)by in situ esterification was obviously higher when compared with the control one.Therefore,it may be inferred that the hydrolysate of bioaugmentation was mainly inclined to longer-chain fatty acid rather than to VFA.Anyway,an FAMEs yield of 9.24%(wt%)from dried sludge was attained after the 12-d bioaugmentation hydrolysis and succedent esterification.This value was not only higher than that of the control one but also higher than that reported in previous literature.The above results illuminated that it was feasible to produce biodiesel from the bioaugmented hydrolysate of waste sludge.
文摘The concentration of volatile fatty acids （VFA） determined from a previous study was used to determine the concentration of carbon dioxide （CO2） and methane （CH4） in pig digesta using the model developed for ruminant animals. Digesta from the stomach, cecum and colon of pigs （n = 3 dietl） were used for the determination of VFA. The pigs were fed either a low fiber diet （LFD; 8.3% aNDF） as control, or one of the high-fiber diets （HFD, 22.4% aNDF; D1, D2 and D3） containing 1：2, 1：1 and 2：1, oats to barley ratios, respectively. Results indicated that the concentrations of CO2 and CH4 in pigs fed HFD were, on the average, 25.8 and 24.2%, respectively lower （P 〈 0.05） than pigs fed LFD. Pigs fed the highest oat to barley ratio also showed higher （P 〈 0.05） levels of CO2, （8.3%） and CH4 （5.1%）, compared to the average of the two lower ratios （CO2, 5.3% and CH4, 3.3%）. Molar proportions of VFA, CO2 and CH4 in the gut were in the order of VFA 〉 CO2 〉 CH4, at 53.0%, 28.6% and 18.4%, respectively, and CO2 and CH4 combined represented 47% of total gas.
文摘Ninety six pigs average weight 9.15 kg were used to study the effects of feeding diets containing multiple sources of dietary fiber （DF） on weight gain and concentration of fermentation products in the digestive tract. The experiment employed four diets and four pens diet1. Diets included a low fiber diet （LFD）, as control and three antibiotic free high-fiber diets （HFD） containing a 1：2, 1：1 or 2：1 oats：barley ratios. At the end of the 70 d feeding trial three pigs of comparable weight diefI were slaughtered. Digesta taken from the stomach, cecum and colon were used for the determination of volatile fatty acids （VFA）. Results indicated that inclusion of HFD increased （P 〈 0.05） feed intake but not weight gain. As revealed by the higher feed intake the nutritional value of HFD was approximately 88% of LFD. Also, as the amount of oats in the diet was increased, VFA concentration was also increased while isobutyrate decreased （P 〈 0.05）. Lower concentration of isobutyrate may indicate parallel reduction in other putatively toxic products of protein fermentation in the digestive tract. Thus, inclusion of multiple sources of fiber in the diet impacted feed intake and the products of gut fermentation in growing pigs.
基金Supported by Science and Technology Breakthrough Major Project in Henan Province(112101210200)
文摘The solubility of D-xylose in formic acid and binary solvents of formic acid with formic acid and acetic acid, propionic acid, n-butyric acid or isobutyric acid was measured in the temperature range from 300.35 to 325.05 K using the synthetic method by a laser monitoring technique at atmospheric pressure. The solid-liquid equilibrium data will provide essential support for industrial design and further theoretical study. The experimental data show that the solubility of D-xylose in formic acid and in the mixtures of formic acid + acetic acid(1︰1), formic acid + propionic acid(1︰1), formic acid + n-butyric acid(1︰1), and formic acid + isobutyric acid(1︰1) increases with temperature. The Apelblat equation, the λh model, and the ideal solution equation correlate the solubility data well.
文摘The study evaluated impact of psychrophilic anaerobic digestion on levels of viable populations of fecal indicator bacteria using various inoculum-to-substrate ratios （I：S）. Laboratory-scale batch reactors were maintained at 10 ℃ and 20 ℃ for 25 days with dairy manure substrate. Five treatments included inoculum （control inoculum; inoculum only [CI]）, manure （control manure; substrate only [CM]）, and 3I：1S, II：IS, and 1I：3S. E. coli decreased in all treatments, while Enterococci decreased in only a few treatments. Treatment 1 I： 1S achieved highest E. coli decrease at 20 ℃ （3.11 log）; CM showed highest E. coli decrease at 10 ℃ （2.33 log）. The 1I：3 Streatment showed highest decrease of Enterococci at 20 ℃ （1.82 log）, whereas CM had highest, but less substantial, decrease at 10 ℃ （0.49 log）. These decreases may be the result of environmental conditions, namely substrate limitation for E. coli, and, increased VFA （volatile fatty acid） levels for Enterococci. Lower I：S showed higher levels of indicator organisms; less stable conditions with more acidic pH, higher VFAs, and lower biogas production. Results suggest II：IS is ideal for starting a digester at 20 ℃, whereas 3I：1S appears optimal for 10 ℃, Overall, I：S influenced chemical parameters and fecal indicators during batch psychrophilic anaerobic digestion of manure.
文摘The aim of this study was to assess the effect of inclusion of fermented apple bagasse （FAB） obtained through solid state fermentation on pH, ammonia nitrogen （N-NH3）, volatile fatty acids （VFA） content, in vitro dry matter digestibility （IVDMD）, lactic acid and microbial counting of alfalfa hay under in vitro rumen environment; four levels of FAB were evaluated （0, 0.25, 0.50 and 0. 75 g/dry matter of FAB） replacing 1.5 g dry matter （DM） of alfalfa hay and incubated at different fermentation times （0, 4, 8, 12 and 24 h） using a complete random design with repeated measures on time. Counts of live yeast colonies （6.08, 6.33, 6.24 and 6.51 CFU/mL expressed as log 10） was higher when FAB was included in the different levels up to the 12 h of fermentation （P 〈 0.0001）; lactic acid content also increased as FAB was included in the different levels （10.61, 13.86, 16.84 and 14.57μg/mL） up to the 12 h of incubation （P 〈 0.001）. Nevertheless, the other variables measured as pH, N-NH3, VFA, IVDMD, total bacteria and fungi counts, were not affected by the treatments. It is concluded that substitution of FAB by alfalfa hay in an in vitro rumen ecosystem positively modified live yeast colonies and lactic acid concentration, without effect on the other fermentative and microbial parameters of the in vitro rumen environment, but considering mixes of FAB and alfalfa hay as a quality ingredient for the feeding of ruminants.
文摘This experiment was conducted using by-products from agro-industry as dairy cows feed. Bagasse, pineapple peel, corn cob, corn stover and vinasses were used to produce TMF （total mixed fiber） for dairy cow feed. Fifteen multiparous Holstein Friesian dairy cows with an initial body weight of 417.88± 52.60 kg and 83.31 ± 26.47 DIM （days in milk） were randomly allocated to three treatments （TI = rice straw and 1 kg of vinasses; T2 = SCWS （sweet corn waste silage）; T3 = TMF （total mixed fiber）） under completely randomized design. The results showed that the chemical composition of TMF was in the normal range of pH and VFA （volatile fatty acids） on silage. However, cows fed TMF and SCWS tended to yield higher level of NH3-N. For volatile fatty acid in rumen fluid, acetate in group of cows fed rice straw with vinasse tended to be the highest. Moreover, propionate in cows fed TMF was found to be the highest among all treatments （P 〉 0.05）. In conclusion, the TMF can be used to feed dairy cow without affecting rumen parameter.
文摘The textile processing plants utilize a wide variety of dyes and other chemicals such as acids, bases, salts, detergents, sizes, oxidants, mercerizing and finishing chemicals. Many of these are not retained in the final product and are discharged in the effluent. Therefore, the objective of this study was to assess the performance of Expanded Granular Sludge Bed （EGSB） reactor to treat synthetic textile wastewater. Several experiments using Direct Red 81 and volatile fatty acids as model substrates were conducted. The problems of decolorization was evaluated at a variety of relevant operational conditions, such as substrate concentration, organic and hydraulic loading rates. The results showed that retention time of EGSB equals 1.6 h and 80 mg/L at the hydraulic and dye concentration respectively, and that the color removal efficiency can reach 90%. Additionally, some chemical additions were proposed to improve the decolorization rate and increase the treatment efficiency of the system. For instance, sulfide was added at 200 mg/L in the influent, which can increase the dye removal efficiency to 95%.
文摘The textile processing plants utilize a wide variety of dyes and other chemicals such as acids, bases, salts, detergents, sizes, oxidants, mercerizing and finishing chemicals. Many of these are not retained in the final product and are discharged in the effluent. Therefore, the objective of this study was to assess the performance of EGSB （Expanded Granular Sludge Bed） reactor to treat non-acidifie wastewater. Several experiments using starch and volatile fatty acids as model substrates were conducted. The problems of piston formation were evaluated at a variety of relevant operational conditions, such as substrate concentration, organic and hydraulic loading rates. The results showed that newly grown acidogenic biomass diluted original methanogenic biomass and the granular sludge in the EGSB reactor deteriorated. The piston formation in the EGSB reactor that was fed with non-acidified wastewater occurred due to high growth of acidogenic biomass and high upflow velocity applied in the system.
