A method and apparatus for treating a fluid using a wave energy uses a gas-sparged pipe configured to create a flow of the fluid in a thin film along a vortex path from a first end to a second end of the gas-sparged pipe, a first electrode and a second electrode that are at least partially disposed within the gas-sparged pipe, spaced apart from one another, and axially aligned with one another along a central axis of the gas-sparged pipe from the first end to the second end. The electrodes are used to create an open electrical arc to provide the wave energy directly exposing the fluid as the fluid flows along the vortex path in close proximity to and surrounding the electrical arc such that only a gas separates the fluid from the open electrical arc.