Abstract: Phosphate-contaminated water passes through a domestic sewage treatment system, in which oxidation of the ammonium progresses far enough to cause a lowering of the pH to 5 or less. The water is passed over sand grains coated with aluminum hydroxide (gibbsite). Enough Al3+ ions enter solution, at the low pH, to cause all the phosphate-P to precipitate as aluminum phosphate, and nothing else precipitates other than the aluminum phosphate.

Abstract: Phosphate-contaminated water passes through a domestic sewage treatment system, in which oxidation of the ammonium progresses far enough to cause a lowering of the pH to 5 or less. The water is passed over sand grains coated with aluminum hydroxide (gibbsite). Enough Al3+ ions enter solution, at the low pH, to cause all the phosphate-P to precipitate as aluminum phosphate, and nothing else precipitates other than the aluminum phosphate.

Abstract: A new method of forming mask ROM in the manufacture of an integrated circuit device has been achieved. A semiconductor substrate is provided with field oxide areas defined and a gate oxide layer overlying the semiconductor substrate. A gate electrode layer is deposited overlying the gate oxide layer. The gate electrode layer and the gate oxide layer are patterned to form gate electrodes. Ions are implanted to form source and drain junctions. A buffer layer is deposited overlying the gate electrodes, the source and drain junctions, and the field oxide areas. The buffer layer is etched down to expose the gate electrodes while leaving a protective thickness of the buffer layer overlying the source and drain junctions. Ions are implanted through the gate electrodes into the semiconductor substrate to selectively code the mask ROM devices and to complete the mask ROM devices in the manufacture of the semiconductor device. A coding mask controls the ion implantation to selectively code the mask ROM.