Abstract: An aeration balance controller in a wastewater treatment process allows for precise control of aeration medium in situations where the oxygen concentration must be controlled in more than one aeration zone or compartment, with reduced instrumentation. The system also has application controlling aeration media where the aeration of one or more zones may interfere with the stable control of aeration in another zone. This is accomplished by the use of two control schemes: one which determines the overall aeration effort required, and one or more controllers which adjust the balance between zones to equalize the process error from setpoint from zone to zone.

Abstract: An aeration balance controller in a wastewater treatment process allows for precise control of aeration medium in situations where the oxygen concentration must be controlled in more than one aeration zone or compartment, with reduced instrumentation. The system also has application controlling aeration media where the aeration of one or more zones may interfere with the stable control of aeration in another zone. This is accomplished by the use of two control schemes: one which determines the overall aeration effort required, and one or more controllers which adjust the balance between zones to equalize the process error from setpoint from zone to zone.

Abstract: An underwater viewing apparatus is provided in combination with a boat having a hull. The apparatus includes a hollow housing open at each end. The lower end of the housing is secured to the bottom of the hull in registry with an opening cut through the hull so that the housing extends vertically upwardly and so that the upper end of the housing is positioned above the water line for the boat. A transparent sheet is positioned over the hull opening and fluidly sealed to both the hull and the housing so that in the event of breakage of the transparent sheet, water will flow through the hull opening only into the interior of the housing and only up to the water level of the boat.