The present disclosure is directed to an apparatus having a separator and mixing equipment. The separator is operable to receive exhaust from fuel-burning equipment at a wellsite and separate the exhaust into a gas component and water. The mixing equipment is operable to receive at least one of the gas component and the water to form a subterranean formation treatment fluid. The present disclosure is further directed to a method of operating fuel-burning equipment at a wellsite to form an exhaust and utilizing the exhaust to form a fluid for injecting into a wellbore to treat a subterranean formation into which the wellbore extends.