Abstract: The methods and apparatus of embodiments of the present invention serve to precipitate dissolved inorganic arsenic from an aqueous solution. The pressurization/negative pressurization protocol promotes precipitation of dissolved inorganic arsenic. After pressurization/negative pressurization method is applied the newly created precipitates may be separated from the solution using known separation methods. Aeration of the solution prior to or during pressurization and addition of chemical oxidants and air injection prior to or during pressurization aid precipitation. The methods of embodiments of the present invention may be applied to batch-process and continuous, in-flow apparatus.

Abstract: A system, method, and article of manufacture suitable for determining setpoints of the control variables to optimize the process while taking into account the process-limiting variables in applications where responses are highly non-linear. In a preferred embodiment, the method comprises determining an actual rate of change of a performance limiting process parameter; calculating a predicted rate of change for the performance limiting process parameter for a predetermined future time interval; and adjusting a setpoint for the control variables to optimize the process while taking into account the performance limiting process parameter using the actual rate of change and the predicted rate of change.