Laserfiche WebLink
Selective Enumerations - Represents only those microorganisms, which are capable of <br /> specifically degrading the target contaminant <br /> Percentage De aders - Tins number represents the percentage of selective organisms <br /> capable of degrading the target contaminant when compared to the heterotrophic/general <br /> population If a given sample had 100 general orgaiusms and 15 selective organisms, it <br /> would be stated that the sample had a 15% degrader population <br /> All references to microbial counts are expressed in Colony Forming Units (CFU's) per <br /> gram of soil tunes 105 Example if the heterotrophic count was 5 2 and the selective <br /> count was 52 this would mean that there were 520,000 microbes per gram of soil in the <br /> given sample, but only 52,000 of these microbes are capable of degrading the <br /> contaminant of concern Following each comparison will be a number in parenthesis <br /> which represents the overall percentage of microbes which are capable of biodegrading <br /> the contaminant of concern The previous example would have had ( 10) following the <br /> selective count referring to the fact that 10% of the total population of microbes could <br /> remediate the contaminant of concern As a general rule of thumb, 20% of the total <br /> microbial population capable of degrading the contaminant with adequate nutrient levels <br /> could be considered acceptable depending on contaminant concentration <br /> All microbial enumerations were performed by taking sample dilution's and inoculating <br /> them onto 50% Plate Count Agar for heterotrophic/general microbial growth, and 50% <br /> • Bushnefl-Haas Agar media supplemented with gasoline for selective microbial growth <br /> All media was prepared at site specific pH and incubated at 300C for six days A single <br /> dilution for all samples was conducted m triplicate, with the results being reported as an <br /> average of the three <br /> Prior to beginning the studies, background samples were analyzed from locations within <br /> the plume (VE-1 @ 25' and VE-1 @ 40') and outside of the plume (SB14 @ 25' and <br /> SB 14 @ 40') The samples -within the plume yielded very low recoveries of both <br /> heterotrophic and selective microorganisms These samples contained what -,xro,.ld <br /> appear to be adequate levels of nutrients for bioremediatior, to occur The samples <br /> outside of the established plume had increased levels of both heterotrophic and selective <br /> microbes over inside the plume howe�er they would also be considered below what <br /> would be acceptable for remediation, they contained increased levels of both nitrate and <br /> ammonium nitrate The increased levels of nitrate outside of the plume vs inside the <br /> plume could indicate that the nitrate is not being utilized because there is no contaminant <br /> to remediate The increased levels of ammonium nitrate could indicate that anaerobic <br /> remediation is occurring <br /> Effects of Nutrient Augmentation on Microbial Growth <br /> This study's were performed over a 21-day period, and conducted to comparatively <br /> evaluate the effects of nutrient supplementation on microbial kinetics This study <br /> . involved samples from location VE-1 taken at a depth of 25 feet from the site This study <br /> was undertaken to determine if nutrient levels at the site may be a contributing factor in <br /> limiting microbial growth and biodegradation, and to determine what effect nutrient <br /> augmentation would have on microbial growth <br />