Quantifying the transport of pathogenic and nonpathogenic Escherichia coli in Magnesium and Nitrogen doped biochar amended sand columns




Quinn, Katherine

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The present study quantifies the transport of Escherichia coli pathogenic O157:H7 and nonpathogenic E. coli k12 strains in water-saturated sand columns amended with Magnesium and Nitrogen-doped biochars produced by pyrolysis at 400, 500, 600, and 7000C. Overall, the addition of the doped biochar to sand at 2% weight ration enhanced the retention of the bacterial cells in the sand/biochar columns. Our results show that: 1) the use of 2% doped biochar to sand had a similar retention of the E. coli O157:H7 compared to that quantified when 20% ratio of un-doped biochar to sand was used in our previous work 1; 2) the retention of E. coli O157:H7 was about 3-fold higher than that of E. coli k12 in all biochar amended sand columns; 3) biochar is hydrophobic while sand and bacteria are hydrophilic; and 4) all kinds of forces investigated (van der Waals, electrostatic, and acid-base interactions) played a role in governing the interactions between bacteria and biochar. In summary, when all physiochemical factors affecting the retention of E. coli in biochar/sand amended columns were considered, the biochar produced at 6000C was the most effective (Figure 1). Our results suggest that designing effective biochar filters includes considering the roles of all the forces that may have a role in governing the transport of bacteria in biochar/sand columns and needs to be tailored based on sand and biochar type used, bacteria involved as well as environmental chemistry. Figure 1. Visual representation of retention of pathogenic and nonpathogenic E. coli with different porous media


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Biomedical Engineering