Abstract: Succinic acid is produced by bringing a succinic acid-containing liquid containing succinic acid and cation which is obtained by fermentation or an enzymatic method into contact with an H-type strongly acidic cation-exchange resin in an amount equivalent to or more than the amount of cation other than hydrogen ion contained in the succinic acid-containing liquid, and precipitating a crystal of succinic acid from the obtained ion-exchange-treated liquid to obtain purified succinic acid.

Abstract: A process for producing an alkali metal polyphosphate, comprising heating a solution comprising a solvent, alkali metal ions, phosphate ions, and 3 to 50% by weight of organic matter, wherein the solution contains, in total, 5 to 65% by weight of the alkali metal ions and the phosphate ions, and the ratio M/P is 1.0 to 3.0, wherein M is the number of moles of alkali metal ions in the solution and P is the number of moles of orthophosphate ions in the solution, at a temperature of 800.degree. to 1200.degree. C. in the presence of excess air, optionally after the solution is at least partially dried to solid, to produce the alkali metal polyphosphate.