Phenol is an important commodity for the chemical industry, used for many processes and deemed to be a major pollutant due its xenobiotic nature and high toxicity. For the purpose of phenol bioremediation a biotechnol...Phenol is an important commodity for the chemical industry, used for many processes and deemed to be a major pollutant due its xenobiotic nature and high toxicity. For the purpose of phenol bioremediation a biotechnological set up consisting of a continuous packed column bioreactor with Candida tropicalis adhered onto activated carbon beads has been previously described. In this work, we show how the integration of available experimental data of such a biotechnological set up into a mathematical model, can lead both to a better comprehension of the underlying physiological mechanisms operating in the cell culture, and to the identification of the system parameters optimum performance. The model so constructed describes the dynamics of phenol uptake and growth rates by the adhered and suspended biomass;the lethality rates;the adhered biomass removal into suspension or adherence onto carbon beads rates and the phenol and biomass (adhered and suspended) concentrations. It also serves to identify different physiological states for the adhered and the suspended biomass;its predictions being verified by comparing with experimental observations. Based on the model description, different optimization strategies are proposed, some of which have been experimentally tested, encompassing changes in bioreactor operation conditions, process development and strain development.展开更多
A new bioreactor on the basis of a dynamic fluidized bed was designed, which combines advantages of the fluidized bed and a biological contactor. The experiments of start-up, nor- mal operation and parameter adjustmen...A new bioreactor on the basis of a dynamic fluidized bed was designed, which combines advantages of the fluidized bed and a biological contactor. The experiments of start-up, nor- mal operation and parameter adjustment are carried out. The re- sults show that the bioreactor can be quickly started up in the condition that the fill is 50%, the hydraulic retention time is 72 min, aerate speed is 2.5 m3/h, rotation-cage rotated speed is 1.5 r/min, and the removal rates of chemical oxygen demand (CODCr) and Ammonia nitrogen (NH3-N) are 75.34% and 80.98% respec- tively. The influence of the operation parameter on removal rates of the bioreactor is analyzed, and an appropriate operation pa- rameter is provided.展开更多
Bed expansion serves an important function in the design and operation of an upflow anaerobic reactor. An analysis of the flow pattern of expanded granular sludge bed （EGSB） reactors shows that most EGSB reactors do...Bed expansion serves an important function in the design and operation of an upflow anaerobic reactor. An analysis of the flow pattern of expanded granular sludge bed （EGSB） reactors shows that most EGSB reactors do not behave as expanded bed reactors, as is widely perceived. Rather, these reactors behave as fluidized bed reactors based on the classic chemical reactor theory. In this paper, four bed expansion modes, divided as static bed, expanded bed, suspended bed, and fluidized bed, for bioreactors are proposed. A high-rate anaerobic suspended granular sludge bed （SGSB） reactor was then developed. The SGSB reactor is an upflow anaerobic reactor, and its expansion degree can be easily controlled within a range to maintain the suspended status of the sludge bed by controlling upfiow velocity. The results of the full-scale reactor confirmed that the use of SGSB reactors is advantageous. The full-scale SGSB reactor runs stably and achieves high COD removal efficiency （about 90%） at high loading rates （average 40 kg-COD·m^-3·d^-1, maximum to 52 kg·COD·m^-3 ·d^-1） based on the SGSB theory, and its expansion degree is between 22% and 37%.展开更多
Three laboratory-scale moving bed biofilm reactors （MBBR） with different carrier filling ratios ranging from 40% to 60% were used to study the effects of carrier-attached biofilm on oxygen transfer efficiency. In th...Three laboratory-scale moving bed biofilm reactors （MBBR） with different carrier filling ratios ranging from 40% to 60% were used to study the effects of carrier-attached biofilm on oxygen transfer efficiency. In this study, we evaluated the performance of three MBBRs in degrading chemical oxygen demand and ammonia. The three reactors removed more than 95% of NH4^＋ -N at an air flow-rate of 60L·h^-1. The standard oxygen transfer efficiency （αSOTE） of the three reactors was also investigated at air flow-rates ranging from 60 to 100L·h^-1. These results were compared to αSOTE of wastewater with a clean carrier （no biofilm attached）. Results showed that under. these process conditions, αSOTE decreased by approximately 70% as compared to αSOTE of wastewater at a different carrier-filling ratio. This indicated that the biofilm attached to the cartier had a negative effect on αSOTE. Mechanism analysis showed that the main inhibiting effects were related to biofilm flocculants and soluble microbial product （SMP）. Biofilm flocs could decrease otSOTE by about 20%, and SMP could decrease aαSOTE by 30%--50%.展开更多
文摘Phenol is an important commodity for the chemical industry, used for many processes and deemed to be a major pollutant due its xenobiotic nature and high toxicity. For the purpose of phenol bioremediation a biotechnological set up consisting of a continuous packed column bioreactor with Candida tropicalis adhered onto activated carbon beads has been previously described. In this work, we show how the integration of available experimental data of such a biotechnological set up into a mathematical model, can lead both to a better comprehension of the underlying physiological mechanisms operating in the cell culture, and to the identification of the system parameters optimum performance. The model so constructed describes the dynamics of phenol uptake and growth rates by the adhered and suspended biomass;the lethality rates;the adhered biomass removal into suspension or adherence onto carbon beads rates and the phenol and biomass (adhered and suspended) concentrations. It also serves to identify different physiological states for the adhered and the suspended biomass;its predictions being verified by comparing with experimental observations. Based on the model description, different optimization strategies are proposed, some of which have been experimentally tested, encompassing changes in bioreactor operation conditions, process development and strain development.
文摘A new bioreactor on the basis of a dynamic fluidized bed was designed, which combines advantages of the fluidized bed and a biological contactor. The experiments of start-up, nor- mal operation and parameter adjustment are carried out. The re- sults show that the bioreactor can be quickly started up in the condition that the fill is 50%, the hydraulic retention time is 72 min, aerate speed is 2.5 m3/h, rotation-cage rotated speed is 1.5 r/min, and the removal rates of chemical oxygen demand (CODCr) and Ammonia nitrogen (NH3-N) are 75.34% and 80.98% respec- tively. The influence of the operation parameter on removal rates of the bioreactor is analyzed, and an appropriate operation pa- rameter is provided.
基金Acknowledgements This study was supported by the National Natural Science Foundation of China （Grant Nos. 50978146 and 51278271） and by the Environmental Scientific Research in the Public Interest （No. 201009017） from the Ministry of Environmental Protection of China.
文摘Bed expansion serves an important function in the design and operation of an upflow anaerobic reactor. An analysis of the flow pattern of expanded granular sludge bed （EGSB） reactors shows that most EGSB reactors do not behave as expanded bed reactors, as is widely perceived. Rather, these reactors behave as fluidized bed reactors based on the classic chemical reactor theory. In this paper, four bed expansion modes, divided as static bed, expanded bed, suspended bed, and fluidized bed, for bioreactors are proposed. A high-rate anaerobic suspended granular sludge bed （SGSB） reactor was then developed. The SGSB reactor is an upflow anaerobic reactor, and its expansion degree can be easily controlled within a range to maintain the suspended status of the sludge bed by controlling upfiow velocity. The results of the full-scale reactor confirmed that the use of SGSB reactors is advantageous. The full-scale SGSB reactor runs stably and achieves high COD removal efficiency （about 90%） at high loading rates （average 40 kg-COD·m^-3·d^-1, maximum to 52 kg·COD·m^-3 ·d^-1） based on the SGSB theory, and its expansion degree is between 22% and 37%.
基金This study was supported by the National Natural Science Foundation of China （Grant No. 51408601）.
文摘Three laboratory-scale moving bed biofilm reactors （MBBR） with different carrier filling ratios ranging from 40% to 60% were used to study the effects of carrier-attached biofilm on oxygen transfer efficiency. In this study, we evaluated the performance of three MBBRs in degrading chemical oxygen demand and ammonia. The three reactors removed more than 95% of NH4^＋ -N at an air flow-rate of 60L·h^-1. The standard oxygen transfer efficiency （αSOTE） of the three reactors was also investigated at air flow-rates ranging from 60 to 100L·h^-1. These results were compared to αSOTE of wastewater with a clean carrier （no biofilm attached）. Results showed that under. these process conditions, αSOTE decreased by approximately 70% as compared to αSOTE of wastewater at a different carrier-filling ratio. This indicated that the biofilm attached to the cartier had a negative effect on αSOTE. Mechanism analysis showed that the main inhibiting effects were related to biofilm flocculants and soluble microbial product （SMP）. Biofilm flocs could decrease otSOTE by about 20%, and SMP could decrease aαSOTE by 30%--50%.
