Ammonium and nitrite are two substrates of anammox bacteria, but they are also inhibitors under high concentrations. The performance of two anaerobic ammonium-oxidizing (anammox) upflow biofilm (UBF) reactors was inve...Ammonium and nitrite are two substrates of anammox bacteria, but they are also inhibitors under high concentrations. The performance of two anaerobic ammonium-oxidizing (anammox) upflow biofilm (UBF) reactors was investigated. The results show that anammox UBFs become unstable under nitrogen loading rate (NLR) applied higher than 1.0 g/(L·d). The consumptions of acidity in the anammox reaction lead to the increase of pH, which is as high as 8.70-9.05. Free nitrous acid concentration is accompanied to be lower than the affinity constant of anammox bacteria, and then starvation effect appears. Moreover, free ammonia concentration increases to 57-178 mg/L, resulting in inhibitory effect on the anammox bacteria. Both negative effects contribute to the instability of the anammox bioreactors.展开更多
Electrokinetic and contact angle measurements were used to discuss the interfacial interaction on bio-leaching of pyrite mineral. Surface energy parameters of pyrite mineral and thiobacillus ferrooxidans were obtained...Electrokinetic and contact angle measurements were used to discuss the interfacial interaction on bio-leaching of pyrite mineral. Surface energy parameters of pyrite mineral and thiobacillus ferrooxidans were obtained by calculating according to formula of Young＇s equation and contact angle measurements. The results show that surface energy of thiobacillus ferrooxidans is much higher than that of pyrite mineral, and the reaction of pyrite mineral with thiobacillus ferrooxidans causes the reduction of the pyrite surface energy. The interfacial interaction energies between pyrite mineral and thiobaciUus ferrooxidans were also obtained based on polar interfacial interaction theory and electrokinetic and contact angle measurements. The thermodynamics approach only considering Lifshitz-van der Waals and Lewis acid-base interaction fails to explain the adhesion behavior of the bacteria, but the extended Derjaguin-Landan-Verwey-Overbeek theory concerning Lifshitz-van der Waals and Lewis acid-base and the electrostatic can exactly predict interfacial interaction.展开更多
The role of Fe/S ratios(ω, g/g) in the uranium bioleaching from a complex uranium ore by Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans consortium was investigated. The results showed good uranium e...The role of Fe/S ratios(ω, g/g) in the uranium bioleaching from a complex uranium ore by Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans consortium was investigated. The results showed good uranium extraction with over 90% at the Fe/S ratio of 5:0.5, 5:1 and 5:5, while poor extraction(<46%) at the Fe/S ratio of 5:0 and 5:10.Furthermore, the bacterial community analysis based on species-specific gyrB numbers indicated that, absent sulfur or excessive sulfur would be not conducive to the synergistic growth for A. ferrooxidans and A. thiooxidans, and then not conducive to the uranium dissolution. Meanwhile, the sulfur-oxidizers could play an important role in the process of uranium synergistic bioleaching by mixed bacterial consortia. Additionally, the characteristics of mineral residue was detected by SEM-EDS. The results showed appropriate sulfur dosage would change the structure and improve the porosity of passivation substance. Lastly, the uranium dissolution kinetics and biochemical reaction mechanism was analyzed. It indicated that the biochemical reaction coupling iron and sulfur had a pleiotropic effect on the uranium dissolution from the ore particles, appropriate Fe/S ratio is the key factor for uranium bioleaching by chemoautotrophic acidophiles.展开更多
基金Project(2006AA06Z332) supported by the National High-Tech Research and Development Program of ChinaProject(30770039) supported by the National Natural Science Foundation of ChinaProject(2008BADC4B05) supported by the National Science and Technology Pillar Program
文摘Ammonium and nitrite are two substrates of anammox bacteria, but they are also inhibitors under high concentrations. The performance of two anaerobic ammonium-oxidizing (anammox) upflow biofilm (UBF) reactors was investigated. The results show that anammox UBFs become unstable under nitrogen loading rate (NLR) applied higher than 1.0 g/(L·d). The consumptions of acidity in the anammox reaction lead to the increase of pH, which is as high as 8.70-9.05. Free nitrous acid concentration is accompanied to be lower than the affinity constant of anammox bacteria, and then starvation effect appears. Moreover, free ammonia concentration increases to 57-178 mg/L, resulting in inhibitory effect on the anammox bacteria. Both negative effects contribute to the instability of the anammox bioreactors.
基金Project(2004CB619204) supported by the National Basic Research Program of ChinaProject(2002) supported by the Teaching and Research Award Program for Outstanding Young Teachers in Higher Education Institutions, China
文摘Electrokinetic and contact angle measurements were used to discuss the interfacial interaction on bio-leaching of pyrite mineral. Surface energy parameters of pyrite mineral and thiobacillus ferrooxidans were obtained by calculating according to formula of Young＇s equation and contact angle measurements. The results show that surface energy of thiobacillus ferrooxidans is much higher than that of pyrite mineral, and the reaction of pyrite mineral with thiobacillus ferrooxidans causes the reduction of the pyrite surface energy. The interfacial interaction energies between pyrite mineral and thiobaciUus ferrooxidans were also obtained based on polar interfacial interaction theory and electrokinetic and contact angle measurements. The thermodynamics approach only considering Lifshitz-van der Waals and Lewis acid-base interaction fails to explain the adhesion behavior of the bacteria, but the extended Derjaguin-Landan-Verwey-Overbeek theory concerning Lifshitz-van der Waals and Lewis acid-base and the electrostatic can exactly predict interfacial interaction.
基金Project(51804165) supported by the National Natural Science Foundation of ChinaProject(2018JJ3441) supported by the Natural Science Foundation of Hunan Province,China。
文摘The role of Fe/S ratios(ω, g/g) in the uranium bioleaching from a complex uranium ore by Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans consortium was investigated. The results showed good uranium extraction with over 90% at the Fe/S ratio of 5:0.5, 5:1 and 5:5, while poor extraction(<46%) at the Fe/S ratio of 5:0 and 5:10.Furthermore, the bacterial community analysis based on species-specific gyrB numbers indicated that, absent sulfur or excessive sulfur would be not conducive to the synergistic growth for A. ferrooxidans and A. thiooxidans, and then not conducive to the uranium dissolution. Meanwhile, the sulfur-oxidizers could play an important role in the process of uranium synergistic bioleaching by mixed bacterial consortia. Additionally, the characteristics of mineral residue was detected by SEM-EDS. The results showed appropriate sulfur dosage would change the structure and improve the porosity of passivation substance. Lastly, the uranium dissolution kinetics and biochemical reaction mechanism was analyzed. It indicated that the biochemical reaction coupling iron and sulfur had a pleiotropic effect on the uranium dissolution from the ore particles, appropriate Fe/S ratio is the key factor for uranium bioleaching by chemoautotrophic acidophiles.
