Publications by authors named "Gertjan J Medema"

Soil passage of (pretreated) surface water to remove pathogenic microorganisms is a highly efficient process under oxic conditions, reducing microorganism concentrations about 8 log within tens of meters. However, under anoxic conditions, it has been shown that removal of microorganisms can be limited very much. Setback distances for adequate protection of natural groundwater may, therefore, be too short if anoxic conditions apply.

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Article Synopsis
  • To establish protection zones around groundwater wells and safe distances for recharge systems, it's crucial to understand how microorganisms are removed during soil filtration.
  • Column experiments using different soil types showed that the removal rates of various microbial agents were generally efficient but varied based on the soil type, with gravel performing better than fine sandy soil.
  • Factors like soil characteristics and flow rates significantly impact the effectiveness of microbial removal, indicating that simplistic models based on grain and particle sizes can't accurately predict the behavior of microorganisms in subsurface environments.
  • The experiments revealed that common bacteria, such as E. coli, exhibited low removal rates in field conditions, suggesting complexities that challenge the direct application of lab results to real-world scenarios.
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