NOVELTY - A purified saline aqueous composition comprises greater than or equal to 30 g/kg salt, of which the total organic carbon content is 1 mu g to 5 g C/l of composition and which contains at least one carboxylic acid.    USE - A purified saline aqueous composition used as reactant in an electrolysis process for production of commercial chlorine (claimed).    ADVANTAGE - It has been found that it is possible to tolerate the presence of a carboxylic acid and of a high total organic carbon content in the aqueous composition to be electrolyzed. Such characteristics do not affect the performances of the electrolysis process. In particular, the expected reduction of the yield of the electrolysis process due to secondary electrode reactions, electrode overplating, increased overpotentials, foaming, membrane or diaphragm fouling are not observed. That yield can even be increased.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for:    (1) manufacture of aqueous composition comprising reacting a mixture of dichloropropanol containing 1,3-dichloro-2-propanol and 2,3-dichloro-1-propanol, in which the 1,3-dichloro-2-propanol content in the mixture is greater than or equal to 10 wt.% with at least one basic compound in a liquid reaction medium, to form epichlorohydrin and salt(s); subjecting at least one part of liquid reaction medium to a settling operation in which a first fraction containing most of epichlorohydrin which was contained in the part of the reaction medium before the settling operation is separated from a second fraction containing most of the salt which was contained in the part of the reaction medium before the settling operation; and subjecting the second fraction to at least one treatment selected from a physical treatment, a chemical treatment and/or a biological treatment; and    (2) production of epichlorohydrin comprising manufacturing dichloropropanol by chlorination of glycerol with hydrogen chloride; dehydrochlorination of the dichloropropanol with sodium hydroxide in order to obtain epichlorohydrin and an aqueous composition containing sodium chloride; treating the aqueous composition comprising a reaction with active chlorine; electrolyzing the aqueous composition in order to obtain hydrogen, chlorine and sodium hydroxide; optionally reacting a fraction of chlorine with hydrogen obtained in the fourth step and/or a compound selected from propylene, methane, a chlorinated hydrocarbon, and/or a chlorohydrofluorocarbon in order to produce hydrogen chloride and recycling a fraction of hydrogen chloride; optionally reacting a fraction of chlorine obtained in fourth step with silicon to generate silicon tetrachloride and/or ethylene to generate 1,2-dichloroethane and/or carbon monoxide to generate phosgene, and/or submitting silicon tetrachloride and/or 1,2-dichloroethane and/or phosgene to respectively flame hydrolysis, pyrolysis and reaction with amines to produce hydrogen chloride and recycling a fraction of hydrogen; and optionally recycling a fraction of chlorine obtained in fourth step in the third step.