A method of treating hydroxide alkaline waste and by-products to render the material neutralized or reduced in pH from near 14 to a minimum lower limit of about 5.3 based on aluminum poly cation salts, rendering the waste or by-product stream suitable for ultimate disposal or reuse. The method comprises contacting together a mixture of moderate to high alkaline waste or by-product material with a pH in the range of 7.5-14, with sufficient water added or found within the alkaline material, with one or more poly cationic salts in the dry form taken from a group of salts containing tri-valent aluminum, tri-valent iron, di-valent calcium, di-valent magnesium, di-valent manganese, di-valent zinc, or any polyvalent cationic salt that is soluble in water to a minimum extent of 0.5 grams per 100 milliliters of water at near 0.degree. Centigrade and 2 grams per 100 milliliters of water at near 100.degree. Centigrade, in such a way to cause these materials to interact in a double replacement reaction to form a soluble salt reaction by-product and an insoluble hydroxide precipitate with water solubility characteristics, between 0.degree. Centigrade and 100.degree. Centigrade, equal to or exceeding that of CaS04*2H2O (gypsum) or approximately 0.20 grams per 100 milliliters of water. The added salts) may be dry or made up of a brine or dilute salt solution of the chosen salt or salts from the set of poly cation salts suitable to reduce hydroxide alkalinity in waste and by-product materials causing the pH to drop immediately upon thorough mixing of the poly cation salts and the waste/product materials, resulting in a treated waste/by-product stream/that is suitable for ultimate disposal or re-use.