Membrane microfiltration fermentation (MMF) with cell recycling was successfully applied to the production of glucose oxidase (GOD). A plate microfiltration module was found suitable for such purpose. By feeding whole...Membrane microfiltration fermentation (MMF) with cell recycling was successfully applied to the production of glucose oxidase (GOD). A plate microfiltration module was found suitable for such purpose. By feeding whole medium in MMF, the productivity of GOD was much higher than that by feeding glucose alone. With increasing dilution rate the enzyme productivity increased and average enzyme activity decreased. The enzyme productivity of MMF under D = 0.12h-1 and 0.20h-1 were 3871 and 3945U·h-1 respectively, which was about 3 times as that of batch fermentation (BF) and the average enzyme activity was still as high as STU·mL-1 under D = 0.12h-1. The relative efficiency of MMF applied to low yield strain was higher than that applied to high yield strain.展开更多
The mycotoxin, patulin （4-hydroxy-4H-furo [3, 2c] pyran-2 [6H]-one）, is produced by a number of fungi common to fruit and vegetable-based products, most notably apples. Patulin contamination within apple products po...The mycotoxin, patulin （4-hydroxy-4H-furo [3, 2c] pyran-2 [6H]-one）, is produced by a number of fungi common to fruit and vegetable-based products, most notably apples. Patulin contamination within apple products poses a serious health risk to consumers. Studies done on laboratory animals have demonstrated that patulin has a broad spectrum of toxicity, including mutagen city and carcinogenicity. The aim of the experiment was studying influence of selectively acting activated carbon powder--Ercarbon SH （Erbsloh, Germany） which is special produced for lowering HMF （hydroxy methyl furfural）, on reduction of patulin content in clear apple juice. Industrial apple row material with some damaged parts was pressed, juice was pasteurized at 95 ℃ during 2 min. After cooling on 55 ℃, enzymatic treated and clarified juice were filtered by 0.45 [am pore sizes membrane filter, Apple clear juice sample was divided for five parts. The samples of apple juice were diluted to 11.5° Brix and contacted with concentrations of 2, 2.5, 3 and 3.5 g/L activated carbon powder for 30 min. After filtration in the experimental samples, putulin was quantitatively determined by HPLC （high performance liquid chromatography with UV） detector at 276 nm. The research revealed that the best results were achieved by treatment with activated carbon in its powder form at concentration of 2.5 g/L with 30 min contact time.展开更多
A numerical model was established to predict and optimise the chemical cleaning process of Polyvinylidene Fluo- ride （PVDF） Ultrafiltration （UF） membranes with the results from the experiment that applied the Resp...A numerical model was established to predict and optimise the chemical cleaning process of Polyvinylidene Fluo- ride （PVDF） Ultrafiltration （UF） membranes with the results from the experiment that applied the Response Sur- face Method （RSM） and Central Composite Design （CCD）. The factors considered in the experimental design were sodium hydroxide （NaOH） concentration, sodium bypochlorite concentration （NaCIO）, citric acid concentration and cleaning duration, The interactions between the factors were investigated with the numerical model. Humic acid （20 mg· L-1） was used as the model foulant, and chemical enhanced backflush （CEB） was employed to sim- ulate the chemical cleaning process. The concentrations of sodium hydroxide, sodium hypochlorite, citric acid and cleaning duration tested during the experiments were in the range of 0.1%-0.3% 100-300 mg· L-1 1%-3% and 0.5-1.5 h, respectively. Among the variables, the sodium hypochlorite concentration and the cleaning dura- tion showed a positive relationship involving the increased efficiency of the chemical cleaning. The chemical cleaning efficiency was hardly improved with increasing concentrations of sodium hydroxide. However, the data was sharply decreased when at a low level of sodium hydroxide concentration. In total, 54 sets of cleaning schemes with 80% to 100K cleaning efficiency were observed with the R＆M model after calibration.展开更多
Mixed liquid of activated sludge (AS) were micro-filtrated by dynamic membrane (DM) made of 6000 mesh kaolin. The results illustrated that the permeate quality and flux with DM filtration were superior to that with di...Mixed liquid of activated sludge (AS) were micro-filtrated by dynamic membrane (DM) made of 6000 mesh kaolin. The results illustrated that the permeate quality and flux with DM filtration were superior to that with direct filtration in treating AS. The experiments of membrane washing showed that DM could abate the internal fouling of membranes efficiently, and the permeate flux of renewed membrane reached 90% of that of new membranes. The denser the mixed liquid suspended solids (MLSS) were, the lower the permeate flux was. Increasing of both flow velocity over the membrane surface and trans-membrane pressure (TMP) could lead to some enhancement of permeate flux, while the former approach could be carried out more economically. The feasibility of application of the DM to membrane bioreactor (MBR) has been ascertained.展开更多
基金Supported by the National Natural Science Foundation of China(No.39170020).
文摘Membrane microfiltration fermentation (MMF) with cell recycling was successfully applied to the production of glucose oxidase (GOD). A plate microfiltration module was found suitable for such purpose. By feeding whole medium in MMF, the productivity of GOD was much higher than that by feeding glucose alone. With increasing dilution rate the enzyme productivity increased and average enzyme activity decreased. The enzyme productivity of MMF under D = 0.12h-1 and 0.20h-1 were 3871 and 3945U·h-1 respectively, which was about 3 times as that of batch fermentation (BF) and the average enzyme activity was still as high as STU·mL-1 under D = 0.12h-1. The relative efficiency of MMF applied to low yield strain was higher than that applied to high yield strain.
文摘The mycotoxin, patulin （4-hydroxy-4H-furo [3, 2c] pyran-2 [6H]-one）, is produced by a number of fungi common to fruit and vegetable-based products, most notably apples. Patulin contamination within apple products poses a serious health risk to consumers. Studies done on laboratory animals have demonstrated that patulin has a broad spectrum of toxicity, including mutagen city and carcinogenicity. The aim of the experiment was studying influence of selectively acting activated carbon powder--Ercarbon SH （Erbsloh, Germany） which is special produced for lowering HMF （hydroxy methyl furfural）, on reduction of patulin content in clear apple juice. Industrial apple row material with some damaged parts was pressed, juice was pasteurized at 95 ℃ during 2 min. After cooling on 55 ℃, enzymatic treated and clarified juice were filtered by 0.45 [am pore sizes membrane filter, Apple clear juice sample was divided for five parts. The samples of apple juice were diluted to 11.5° Brix and contacted with concentrations of 2, 2.5, 3 and 3.5 g/L activated carbon powder for 30 min. After filtration in the experimental samples, putulin was quantitatively determined by HPLC （high performance liquid chromatography with UV） detector at 276 nm. The research revealed that the best results were achieved by treatment with activated carbon in its powder form at concentration of 2.5 g/L with 30 min contact time.
基金Supported by State Key Laboratory of Urban Water Resource and Environment(2016DX01)the Fundamental Research Funds for the Central University(NSRIF.2014096)Science and Technology Planning Project of Chancheng District(2013A1044)
文摘A numerical model was established to predict and optimise the chemical cleaning process of Polyvinylidene Fluo- ride （PVDF） Ultrafiltration （UF） membranes with the results from the experiment that applied the Response Sur- face Method （RSM） and Central Composite Design （CCD）. The factors considered in the experimental design were sodium hydroxide （NaOH） concentration, sodium bypochlorite concentration （NaCIO）, citric acid concentration and cleaning duration, The interactions between the factors were investigated with the numerical model. Humic acid （20 mg· L-1） was used as the model foulant, and chemical enhanced backflush （CEB） was employed to sim- ulate the chemical cleaning process. The concentrations of sodium hydroxide, sodium hypochlorite, citric acid and cleaning duration tested during the experiments were in the range of 0.1%-0.3% 100-300 mg· L-1 1%-3% and 0.5-1.5 h, respectively. Among the variables, the sodium hypochlorite concentration and the cleaning dura- tion showed a positive relationship involving the increased efficiency of the chemical cleaning. The chemical cleaning efficiency was hardly improved with increasing concentrations of sodium hydroxide. However, the data was sharply decreased when at a low level of sodium hydroxide concentration. In total, 54 sets of cleaning schemes with 80% to 100K cleaning efficiency were observed with the R＆M model after calibration.
文摘Mixed liquid of activated sludge (AS) were micro-filtrated by dynamic membrane (DM) made of 6000 mesh kaolin. The results illustrated that the permeate quality and flux with DM filtration were superior to that with direct filtration in treating AS. The experiments of membrane washing showed that DM could abate the internal fouling of membranes efficiently, and the permeate flux of renewed membrane reached 90% of that of new membranes. The denser the mixed liquid suspended solids (MLSS) were, the lower the permeate flux was. Increasing of both flow velocity over the membrane surface and trans-membrane pressure (TMP) could lead to some enhancement of permeate flux, while the former approach could be carried out more economically. The feasibility of application of the DM to membrane bioreactor (MBR) has been ascertained.
