A system for controlling the injection of wastewater treatment chemicals into a wastewater treatment stream includes a holding tank for collecting and holding wastewater being treated, a camera positioned for making images of the wastewater in the holding tank, a computer for automatically making the images of the wastewater in the holding tank at scheduled intervals. In one embodiment, the telephone employs an internal transmission antenna, and a metallic surface is interposed between the antenna and the user’s head. Lime is added to the spent, sodium sulfate-containing purge liquid to result in the formation of gypsum and sodium hydroxide.