Biochar Pyrolyzed at Two Temperatures Affects Escherichia coli Transport through a Sandy Soil

Abstract

The incorporation of biochar into soils has been proposed as a means to sequester carbon from the atmosphere. An added environmental benefit is that biochar has also been shown to increase soil retention of nutrients, heavy metals, and pesticides. The goal of this study was to evaluate whether biochar amendments affect the transport of Escherichia coli through a water-saturated soil. We looked at the transport of three E. coli isolates through 10-cm columns packed with a fine sandy soil amended with 2 or 10% (w/w) poultry litter biochar pyrolyzed at 350 or 700°C. For all three isolates, mixing the high-temperature biochar at a rate of 2% into the soil had no impact on transport behavior. When added at a rate of 10%, a reduction of five orders of magnitude in the amount of E. coli transported through the soil was observed for two of the isolates, and a 60% reduction was observed for the third isolate. Mixing the low-temperature biochar into the soil resulted in enhanced transport through the soil for two of the isolates, whereas no significant differences in transport behavior were observed between the low-temperature and high-temperature biochar amendments for one isolate. Our results show that the addition of biochar can affect the retention and transport behavior of E. coli and that biochar application rate, biochar pyrolysis temperature, and bacterial surface characteristics were important factors determining the transport of E. coli through our test soil.

Soil Health, Crop Productivity, Microbial Transport, and Mine Spoil Response to Biochars

“…The authors reported that both high-temperature biochars reduced E. coli transport at the 2 % application rate, with substantially greater reductions observed with the pine chip biochar. Application of the low-temperature poultry litter biochar either had no significant effect or increased transport of both E. coli isolatesresults consistent with those discussed above [10]. Changes in transport behavior following biochar addition were quantitatively similar for both saturated and unsaturated soils, but for all treatments, the effect was more pronounced in partially saturated columns.…”

“…One mode of human exposure to these pathogens is through consumption of fecal contaminated groundwater [63,64]. Transport of microbial pathogens into ground water sources may be significantly reduced by application of biochar [9,10]. Those researchers evaluated transport of three different E. coli isolates through laboratory column that were packed with a fine sandytextured soil and then amended with poultry litter biochar produced at two different pyrolysis temperatures (350 or 700°C).…”

“…For example, Novak et al [8] reported that biochar produced from poultry litter had a negative impact on shallow ground water quality by releasing significant concentrations of dissolved phosphorus and by increasing movement of fecal bacteria through the soil [9,10]. On the other hand, biochar produced from pine chips significantly decreased movement of fecal bacteria through fine sand [9].…”

Inactivation ofE. coliO157:H7 in Cultivable Soil by Fast and Slow Pyrolysis-Generated Biochar

“…Soil sampling for presence of E. coli O157:H7 by surface plating Soil was tested for presence and populations of E. coli O157:H7 on day 1 (week 0) as well as at the following storage times: weeks 1, 2, 4, 5, 6, 7, and 8 by cultural sampling methods, as modified from previous studies Bolster et al, 2012;Gurtler et al, 2013). At each sampling time, containers were vigorously mixed for 60 s, 1 g was removed from the container, added to 9 mL TSBN, and vortexed thoroughly.…”

“…Proteobacteria are a phylum containing many foodborne pathogenic microorganisms such as Salmonella, E. coli O157:H7, Shigella, and Vibrio. Others have noted a decrease in Proteobacteria in biochar-amended soils (Anderson et al, 2011), or have investigated effects of biochar on E. coli transport through soils Bolster et al, 2012). Further work is needed to determine effects of biochar on individual pathogens, such as E. coli O157:H7.…”