Transport of MS2 Phage, Escherichia coli, Clostridium perfringens, Cryptosporidium parvum, and Giardia intestinalis in a Gravel and a Sandy Soil

Abstract

To define protection zones around groundwater abstraction wells and safe setback distances for artificial recharge systems in watertreatment, quantitative information is needed about the removal of microorganisms during soil passage. Column experiments were conducted using natural soil and water from an infiltration site with fine sandy soil and a river bank infiltration site with gravel soil. The removal of phages, bacteria, bacterial spores, and protozoan (oo)-cysts was determined at two velocities and compared with field data from the same sites. The microbial elimination rate (MER) in both soils was generally >2 log, but MER in the gravel soil was higher than that in the fine sandy soil. This was attributed to enhanced attachment, related to higher metal-hydroxides content. From the high sticking efficiencies (>1) and the low influence of flow rate on MER it was deduced that straining played a significant role in the removal of Escherichia coli and Cryptosporidium parvum oocysts in the gravel soil. Lower removal of oocysts than the 4-5 times smaller E. coli and spores in the fine sand indicates that the contribution of straining is variable and needs further attention in transport models. Thus, simple extrapolation of grain size and particle size to the extent of microbial transport underground is inappropriate. Finally, the low MER of indigenous E. coli and Clostridium perfringens observed in the soil columns as well as under field conditions and the second breakthrough peak found for Cryptosporidium and spores in the fine sandy soil upon a change in the feedwater pH indicate a significant role of detachment and retardation to microbial transport and the difficulty of extrapolation of quantitative column test results to field conditions.

Drivers of Microbial Risk for Direct Potable Reuse and de Facto Reuse Treatment Schemes: The Impacts of Source Water Quality and Blending

“…The maximum (4.3 LRV) of the modeled distribution is consistent with estimates from a previous review of up to LRV of 4 from conventional drinking water treatment plants [47]. The modelled maximum LRV for Salmonella of 2.7 is comparable with estimates up to the LRV of 3 derived from E. coli data [48,49]. Norovirus removal through conventional drinking water treatment was modeled using a study of bench experiments using a coagulation-rapid sand filtration process with recombinant norovirus virus-like particles in river water [26].…”

Energy forest irrigated with wastewater: a comparative microbial risk assessment

“…Owing to their rather large size, the protozoa Giardia should have a high but variable retention in the soil profile (Logan et al 2001;Hijnen et al 2005). Although the concentrations in groundwater at Kvidinge were substantially lower than at Culmore, a risk of infection when using the groundwater as drinking water occurred.…”

Effects of aquifer thermal energy storage on groundwater quality and the consequences for drinking water production: a case study from the Netherlands

“…Data from field and column experiments reported in literature show however that under Dutch aquifer conditions, a subsurface residence time ranging between 60 to 110 days is generally sufficient to reduce the presence of micro-organisms to an acceptable level (Hijnen et al 2005;Wielen et al 2008). Considering that the ATES system is situated on the edge of the 25 year groundwater protection area, it is unlikely that the PSWF is at risk from microbiological contamination, but additional monitoring to confirm this may be warranted.…”