Abstract: In a biological wastewater treatment process including secondary clarification, the improvement comprising monitoring the salinity of the wastewater flowing to secondary clarification and adjusting the salinity of the wastewater flowing to secondary clarification by adding water or by adding salt.

Abstract: An improved control valve assembly that resists plugging by fluids contaminated with sticky solids, e.g. sludge or particulates, comprising a valve containing a modified valve trim having a stepped cross-section rather than a continuous taper created by reducing the diameter of the valve stem at a point on the stem corresponding to a position of 90 percent open, so that the modification causes the flow area to suddenly increase drastically when the valve opens to 90 percent open in response to flow falling below a predetermined setpoint.

Abstract: A vessel having a floor which includes a tap outlet through which liquid contents in the vessel can be drained. The tap outlet features a shallow aperture circumscribed by first and second drip lines. The second drip line circumscribes the first drip line and is substantially coplanar with the first drip line. The two drip lines are connected one to the other by an annular hollow surface.

Abstract: This invention relates to an apparatus and process for measuring the temperature of a fluid environment within a vessel. The apparatus features a chamber which opens into the vessel and thus contains a portion of the fluid environment. Structure is provided for preventing substantial convective movement between the portion of the fluid environment within the chamber and the remainder of the fluid environment. A temperature sensing device is also provided which is movable from a position within the chamber to a position into the remainder of the fluid environment for obtaining a temperature measurement. The chamber is maintained at a temperature cooler than that of the fluid environment. This invention also relates to a process for the periodic measuring of the temperature of a fluid environment in a vessel.