The study of microbial blockage during the recharge process of ground source heat pumps is of great engineering significance in addressing for solving ground subsidence. The concentration deposition characteristics, breakthrough curve, and permeability coefficient of Escherichia coli in porous media were investigated using a sand layer blockage device. The experimental results show that： （1） the layered position tends to accumulate with Escherichia coli. During reinjection, the accumulated Escherichia coli can be mobilized by increasing the flow rate, thereby increasing the migration path of Escherichia coli, thus improving reinjection efficiency. （2） Under different flow rates, Escherichia coli exhibits different relationships between water pressure and time in two different materials. The uniformity of glass bead pores and smooth surfaces hinder the deposition of Escherichia coli. On the contrary, the internal non-uniformity of gravel facilitates the deposition of Escherichia coli. In practical engineering, increasing the flow rate can help achieve rebound. （3） Escherichia coli generally undergoes three modes of movement in porous media： blockage, migration, and stable accumulation. When the permeability coefficient K decreases, the concentration of Escherichia coli in the end effluent is lower. On the contrary, when the permeability coefficient K increases, the concentration of Escherichia coli in the end effluent is higher. The results have certain practical significance for the long-term stable operation of water source heat pumps.
Key words
water source heat pump /
escherichia coli /
sedimentary characteristics /
permeability coefficient /
surface subsidence
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