Process for manufacturing a chemical: chlorohydrins, epoxides, diols, diols derivatives, epoxy derivatives or mixtures thereof, in an industrial plant, comprising a step of chemical reaction for manufacturing the chemical and at least one step selected from the group consisting of storage, supply, removal, transfer, chemical treatment and physical treatment of compounds used or produced in such process, in which at least one aqueous effluent is generated, this aqueous effluent containing at least one of overhead waters, surface waters, ground waters, waters from drinking water distribution networks, waters from industrial water distribution networks, plant cleaning waters, or waters used for heating and cooling the plant, this aqueous effluent containing at least one compound other than water and exhibiting at least one of the following features, a water solubility at 25° C. greater than or equal to 0.01 g/kg of water and a boiling point at 1013 mbar, greater than or equal to −100° C., in which at least one part of the generated aqueous effluent is collected, and in which at least one portion of the collected aqueous effluent is recycled in the manufacturing process.