A burner assembly for the destruction of noxious vapors and other waste streams includes an inner burner element in the form of a sudden expansion burner and an outer burner element that encircles the inner burner element and forms an annular passageway between the two elements. Waste vapors may be conducted directly into the flame of the inner burner element (direct inject) or routed through the annular passageway and preheated, for injection at the flame or beyond. The burner elements may include solid or perforated cones mounted on their exits to enhance mixing and injection of the streams. The burner assembly may be configured as in inline duct burner. A wide range of contaminants may be processed because waste streams having primarily nonflammable or combustion inhibiting constituents may be processed.