"Pollution control facilities" means any system, method, construction, device or appliance appurtenant thereto, or any portion of any building or equipment, that is designed, constructed, installed or operated for the primary purpose of:
(a) eliminating, preventing, or reducing air or water pollution, as the terms "air pollution" and "water pollution" are defined in the Environmental Protection Act; or(b) treating, pretreating, modifying or disposing of any potential solid, liquid or gaseous pollutant which if released without treatment, pretreatment, modification or disposal might be harmful, detrimental or offensive to human, plant or animal life, or to property. "Pollution control facilities" shall not include, however, (1) any facility with the primary purpose of (i) eliminating, containing, preventing or reducing radioactive contaminants or energy, or (ii) treating waste water produced by the nuclear generation of electric power,(2) any large diameter pipes or piping systems used to remove and disperse heat from water involved in the nuclear generation of electric power,(3) any facility operated by any person other than a unit of government, whether within or outside of the territorial boundaries of a unit of local government, for sewage disposal or treatment, or(4) land underlying a cooling pond.