Groundwater treatment for high temperature heat recovery

Aquifer thermal energy storage (ATES) systems have been utilized to conserve high temperature waste heat from industrial processes. In the heat recovery phase, whenever groundwater with a high level of hardness is heated to temperatures in the range of 50°C or higher, heat exchanger surfaces are susceptible to scale buildup with subsequent clogging of the heat exchanger. In this study, the performance of CO₂ treatment as a means of preventing CaCO₃ scaling in heat exchangers was evaluated. The rate of CO₂ gas injected into the water was controlled by a proportional control valve to maintain a CaCO₃ saturation index of zero. The CO₂ treatment method showed a beneficial effect in controlling scaling on the brass heat exchanger tubes.Key words: aquifer thermal energy storage, CO₂ treatment, CaCO₃ scaling.