Abstract: The steady state condition of a subject product is projected using transient data developed through actual or simulated tests or operations. The transient data represent the monotonic or cyclic property states of the product while subjected to environmental or operational conditions. A first and second property state value corresponding to the transient data for selected times within the test period are identified. A first and second rate-of-change value corresponding to the change in the property states at the selected times are then computed. A time constant value is next computed by applying the time interval and the first and the second rate-of-change values to a time constant function. A projected steady state condition value is next computed by applying the second rate-of-change value, the second state value and the time constant value to a projected steady state conditions function. The projected steady state condition value is compared with a previously computed projected steady state condition value.

Abstract: In a sludge thickener, supernatant fluid is drawn off via peripheral ducts and oxygenated at a suitable location. The supernatant fluid is thereafter reintroduced into the thickener via diffusers distributed transversely of the thickener and intermediate the peripheral ducts. The generation of nauseating smells is thereby prevented, and an advantageous increase of the concentration of the sludges is attained.