Significance of physicochemical factors in the transmission of Escherichia coli and chloride

Organic manures are the source of many pathogenic bacteria which could be dangerousfor human health. Bacterial transmission and retention in soil is important for processes rangingfrom contaminant degradation during in situ bioremediation to transport of pathogenic bacteria intogroundwater.Methods: The aim of this study was to evaluate the transport of Escherichia coli and chloride (Cl) in thesoil saturation conditions, considering the importance of preferential flow using synthetic macrospores(different diameters of macrospores including 0, 1 and 2 cm) and HYDRUS-2D model. Also, theeffect of different salinity levels of water (including electrical conductivity of 1, 2 and 4 dSm-1) on thetransmission of E. coli was investigated. The preferential flow system was prepared and designed usingtwo sand sizes including fine sand and coarse sands in the columns.Results: The results showed that the retention of E. coli increased with the ionic strength of the solution,while the effect of E. coli in the fine sand was greater than that of the coarse sand. This bacterial transferbehavior was well described by numerical simulations. The importance of preferential flow in bacterialtransfer showed that it increases at higher ionic strength, even if overall transmission is reduced.Although the bacterial transmission is facilitated in salinity, the results of this study showed that withincrease of ionic strength of the soil solution, the amount of bacterial purification was increased thatcould be effective in controlling groundwater contamination with saline water management.Conclusion: According to the results, with increase of ionic strength of the soil solution, the amount ofbacterial purification was increased that could be effective in controlling groundwater contaminationwith saline water management, so that the least transition has taken place and the conditions for theuse of unconventional water sources were also created, without the environmental problem of the riskof groundwater pollution.

Keywords:

Escherichia coli , Soil , Water pollution