An adder for use in summing two binary numbers in an arithmetic logic unit of a processor. The magnetic resonance imaging method is further provided with a step for updating the residual magnetic field response function with time depending on the application history of the gradient magnetic field pulses being applied continuously. When crushed, either intentionally or accidentally, and exposed to an aqueous medium, the superabsorbent material present in the core swells to create a hard gel that traps the microparticles. Preferably, the method and apparatus facilitate both activated sludge and fixed film processes.