Biologically produced surfactants （SACs） can mobilize and solubilize non-aqueous phase liquids （NAPL） adsorbed onto soil constituents. The interest in microbial surfactants has increased during recent years due to...Biologically produced surfactants （SACs） can mobilize and solubilize non-aqueous phase liquids （NAPL） adsorbed onto soil constituents. The interest in microbial surfactants has increased during recent years due to their lower toxicity, higher biodegradability, selectivity and specific activity under extreme conditions than synthetic SACs. Main output of the project represents preparation of this yeast biosurfactant intended for washing of matrices contaminated by NAPL. The influence of cultivation media composition on biosurfactant production was studied and basic properties （critical micelle concentration （CMC）, minimum surface tension） of isolated biosurfactants were compared with properties of synthetic surfactant with surface tension measurement. The interracial tension of the systems containing aqueous solutions of different concentrations and non-polar substances was measured with petroleum compounds （kerosene Jet A-l）, aromatic and aliphatic hydrocarbons （represented by toluene and hexane）. The solution of biosurfactant Yarrowia lipolytica （YAR） in the concentration range of 0-500 mg/L reduced interracial tension by 80% in all representative systems with model contaminants; biosurfactant Candida bombicola （CAN） was less efficient. Solubilization properties were proved with toluene and hexachlorocyclohexane （HCH） isomers alpha and gamma, and effective concentration of biosurfactants was determined as 100 mg/L for toluene and HCH. SACs produced by lipophilic yeast with non-toxic and non-pathogenic status （Yarrowia lipolytica, Candida sp., etc.） seem to be very promising. The results obtained will be used for the application of biosurfactants in the clean-up technologies as agents for the mobilization of non-polar contaminants as well as for stimulation of bioremediation processes.展开更多
Objective:Water recycling is a significant part of an overall water management system.The current study evaluated electrocoagulation,used in combination with ultraviolet light(at 254 nm),to reduce the organic content ...Objective:Water recycling is a significant part of an overall water management system.The current study evaluated electrocoagulation,used in combination with ultraviolet light(at 254 nm),to reduce the organic content and enhance the microbiological quality,of wash water derived from shredded lettuce processing.Method:The composition of spent wash water derived from a commercial lettuce processing operation was used to prepare a simulated solution to be applied to validate the water recycling system.The simulated spent wash water was subjected to an electrocoagulation process followed by filtration and a tertiary ultraviolet(254 nm)treatment.The efficacy of the recycling treatment to decrease turbidity(nephelometric turbidity units,biological oxygen demand(BOD),chemical oxygen demand(COD)and decrease in introduced bacterial numbers.Results:Spent wash water sampled from a commercial processing line was found to be colloidal in nature(78±26 NTU)with low total solids content(544±87 mg/L),BOD(230±53 mg/L)and COD(309±53 mg/L).An electrocogaultion process performed for 10 min using 3.48 A/m2 current density at pH 6.5 and conductivity of>100μS/cm supported an 87%removal of turbidity,38%reduction in BOD along with 49%decrease in COD.The electrocoagulation process was also found to reduce the levels of Escherichia coli,Salmonella and Listeria monocytogenes by 1-2 log cfu.The tertiary UV treatment of water derived from the electro coagulation process,supported further reduction in model pathogens,although it was noted that the D values for inactivation were in the order of 1.01-1.60 mJ/cm^(2),which compares to 0.22-0.31 mJ/cm^(2) in saline.The apparent increase in bacterial resistance to ultraviolet was likely due to the UV absorbing low molecular weight constituents within wash water that provided protection against inactivation.Conclusion:In conclusion,the study demonstrated the feasibility of applying electrocoagulation and UV to rapidly treat spent lettuce wash water to facilitate in-process recycling within shredd展开更多
文摘Biologically produced surfactants （SACs） can mobilize and solubilize non-aqueous phase liquids （NAPL） adsorbed onto soil constituents. The interest in microbial surfactants has increased during recent years due to their lower toxicity, higher biodegradability, selectivity and specific activity under extreme conditions than synthetic SACs. Main output of the project represents preparation of this yeast biosurfactant intended for washing of matrices contaminated by NAPL. The influence of cultivation media composition on biosurfactant production was studied and basic properties （critical micelle concentration （CMC）, minimum surface tension） of isolated biosurfactants were compared with properties of synthetic surfactant with surface tension measurement. The interracial tension of the systems containing aqueous solutions of different concentrations and non-polar substances was measured with petroleum compounds （kerosene Jet A-l）, aromatic and aliphatic hydrocarbons （represented by toluene and hexane）. The solution of biosurfactant Yarrowia lipolytica （YAR） in the concentration range of 0-500 mg/L reduced interracial tension by 80% in all representative systems with model contaminants; biosurfactant Candida bombicola （CAN） was less efficient. Solubilization properties were proved with toluene and hexachlorocyclohexane （HCH） isomers alpha and gamma, and effective concentration of biosurfactants was determined as 100 mg/L for toluene and HCH. SACs produced by lipophilic yeast with non-toxic and non-pathogenic status （Yarrowia lipolytica, Candida sp., etc.） seem to be very promising. The results obtained will be used for the application of biosurfactants in the clean-up technologies as agents for the mobilization of non-polar contaminants as well as for stimulation of bioremediation processes.
基金the Ontario Ministry of Agriculture,Food and Rural Affairs for financially supporting the research under the New Directions Program(project#051057).
文摘Objective:Water recycling is a significant part of an overall water management system.The current study evaluated electrocoagulation,used in combination with ultraviolet light(at 254 nm),to reduce the organic content and enhance the microbiological quality,of wash water derived from shredded lettuce processing.Method:The composition of spent wash water derived from a commercial lettuce processing operation was used to prepare a simulated solution to be applied to validate the water recycling system.The simulated spent wash water was subjected to an electrocoagulation process followed by filtration and a tertiary ultraviolet(254 nm)treatment.The efficacy of the recycling treatment to decrease turbidity(nephelometric turbidity units,biological oxygen demand(BOD),chemical oxygen demand(COD)and decrease in introduced bacterial numbers.Results:Spent wash water sampled from a commercial processing line was found to be colloidal in nature(78±26 NTU)with low total solids content(544±87 mg/L),BOD(230±53 mg/L)and COD(309±53 mg/L).An electrocogaultion process performed for 10 min using 3.48 A/m2 current density at pH 6.5 and conductivity of>100μS/cm supported an 87%removal of turbidity,38%reduction in BOD along with 49%decrease in COD.The electrocoagulation process was also found to reduce the levels of Escherichia coli,Salmonella and Listeria monocytogenes by 1-2 log cfu.The tertiary UV treatment of water derived from the electro coagulation process,supported further reduction in model pathogens,although it was noted that the D values for inactivation were in the order of 1.01-1.60 mJ/cm^(2),which compares to 0.22-0.31 mJ/cm^(2) in saline.The apparent increase in bacterial resistance to ultraviolet was likely due to the UV absorbing low molecular weight constituents within wash water that provided protection against inactivation.Conclusion:In conclusion,the study demonstrated the feasibility of applying electrocoagulation and UV to rapidly treat spent lettuce wash water to facilitate in-process recycling within shredd
