A venturi scrubber treats 20,000 acfm of air at atmospheric pressure and 77F. The velocity at the throat entrance is 400ft/sec, and water is introduced at a rate of 7.5 gal/1000ft3 of gas. The venturi throat length is 15 inches. Estimate the pressure drop across the venturi (in inches H2O ), and convert the pressure drop to contacting power (in kWh/1000m3 )