A method for treating contaminates includes delivering a stream of a fluid to a directional microporous diffuser that has a sidewall with microscopic openings and has a partitioned interior region to effect discharge of microbubbles from less than the entire sidewall portion of the directional microporous diffuser at any particular interval of time. The directional microporous diffuser described include an elongated member providing the sidewall, the sidewall defining an interior portion of said member and coupled to the first inlet port and a partition member that divides the interior of the elongated member into plural, mutually isolated regions. End caps are disposed to seal ends of the directional microporous diffuser.