Abstract: A centrifugal pump is provided for transporting pressurized liquids containing solid particles. The pump housing defines a first cylindrical-shaped interior cavity and a second frustoconical interior cavity axially interconnecting the fluid inlet to the pump and the first interior cavity. An impeller includes a plurality of vanes each having a first portion positioned within the first cavity and having an outward axially extending edge spaced uniformly from the central axis of the pump. Each of the vanes includes a second portion positioned within the second cavity and having an outward axially extending edge spaced from the central axis a variable distance directly proportional to its axial spacing from the fluid inlet. The edge of each of the vanes is spaced a preselected distance of at least one quarter inch from the side walls of the housing, such that each of the vanes remains out of sealing engagement with the housing.

Abstract: An improved skimmer is provided for recovering hydrocarbons floating on the surface of a body of water. A floating hull defines first and second tunnels, and a holding tank for housing the collected hydrocarbons. A power driven propeller in the first tunnel draws subsurface water from an inlet port through the first tunnel and out a discharge port. The inlet port of the second tunnel is positioned above the first tunnel to receive floating hydrocarbons and water. The second tunnel has a water outlet in fluid communication with the first tunnel. A skimming gate passes hydrocarbons floating on the surface of water in the second tunnel to the holding tank, and thereby separates hydrocarbons from the water.

Abstract: Improved methods apparatus are provided for introducing and entraining air into a waste liquid, thereby increasing the quantity of dissolved oxygen in the liquid to enhance the aerobic treatment process. A power driven propeller is preferably positioned at the discharge end of conical-shaped transition housing, and draws in air while waste water is controllably introduced to the transition housing from below the surface of the water. The housing upstream from the propeller is primarily an air chamber with incoming streams of water, while the housing downstream from the propeller is filled with waste water having minute entrained air bubbles. The water and entrained air are thus discharged downwardly, and the axis of the equipment preferably inclined to increase circulation in the waste water pond or tank. The techniques of the present invention have relatively low power requirements while substantially increasing gas concentration in the liquid.