A method of and an apparatus for rejuvenating a wastewater treatment system of the type including a septic tank, an aerobic treatment unit or the like connected by a pipe to a plugged downstream soil absorption system includes a wastewater treatment unit which is interposed between the septic unitaerobic treatment unit and the downstream soil absorption system. A transparent substrate having an interferometric modulator array formed thereon is shown. Also disclosed are a method of making an aluminum salt using an increased molar concentration of a starting aluminum salt with a buffer, a method of reducing perspiration with the aluminum chlorohydrate salt, and a method of treating water with the aluminum chlorohydrate salt.