Abstract: On the bases of pilot scale winter-operation experiments of rapid infiltration eco-engineering, the channels of heat supply and its loss in RIsystem during wastewater distribution, its melting, infiltration and exposure are discussed. The mathematical models on thermal balance under naked pond bottom and ice cover conditions are established, and the system design procedure of RIsystem is significantly extended. The effects of site, technology and operating conditions on thermal loss and purification functions of RIsystem are analysed, which provides theorititcal foundations for system design and winter-operation.

Key words: Rapid infiltration, Eco-engineering, Thermal balance, Winter-operation