Transport and fate of bacteria in SAT system recharged with recycling water

Soil aquifer treatment (SAT) system plays an important role in degrading organic pollutants, removing bacteria, N, P and so on during artificial groundwater recharge with recycling water. In order to discover the possibility for the pathogen going through aerated zone and contaminating groundwater, this paper presents an experiment on the transport and fate of the bacteria (Escherichia coli L.) in SAT system, a packed silt soil column, under saturated conditions. The simulated solution considered the basic control index and maximum limit value of groundwater recharge with recycling water. The concentration of bacteria was 105 Colony-Forming Units L−1 in the secondary discharge standard of wastewater treatment plant effluent. The experiment included two recharging stages (firstly for 288 h and secondly for 528 h) with 264 h drying between them. The results showed that there was no detection of E. coli L., and the electric conductivity, total nitrogen, permanganate index became the same finally between the influent and effluent. The concentration of E. coli L. in the solid phase decreased from up to down of the column. This simulation of recycling water recharge could make people understand the transport and fate of contaminants better, and provided reference to practical projects.