John T. Lisle
2016
<h3>Aims</h3>
<p>Inactivation rates of <i>E. coli</i> in groundwater have most often been determined in aerobic and oxidized systems. This study examined <i>E. coli</i> inactivation rates in anaerobic and extremely reduced groundwater systems that have been identified as recharge zones.</p>
<h3>Methods and Results</h3>
<p>Groundwater from six artesian wells was diverted to above ground, flow through mesocosms that contained laboratory grown <i>E. coli</i> in diffusion chambers. All groundwater was anaerobic and extremely reduced (ORP < <span>-</span>300 mV). Cells were plated onto mTEC agar during 21 day incubation periods. All data fit a bi-phasic inactivation model, with > 95% of the <i>E. coli</i> population being inactivated < 11.0 hrs (mean <i>k</i> = 0.488± 0.188 h<span>−1</span>).</p>
<h3>Conclusions</h3>
<p>The groundwater geochemical conditions enhanced the inactivation of <i>E. coli</i> to rates approximately 21-fold greater than previously published inactivation rate in groundwater (mean <i>k</i>= 0.023 ± 0.030 h<span>−1</span>). Also, mTEC agar inhibits <i>E. coli</i> growth following exposure to anaerobic and reduced groundwater.</p>
<h3>Significance and Impact of the Study</h3>
<p>Aquifer recharge zones with geochemical characteristics observed in this study complement above ground engineered processes (e.g., filtration, disinfection), while increasing the overall indicator microorganism log-reduction rate of a facility.</p>
application/pdf
10.1111/jam.13126
en
Wiley
Natural inactivation of <i>Escherichia coli</i> in anoxic and reduced groundwater
article