Use of lignosulfonate for wastewater treatment, containing components of urea-formaldehyderesins
The problem of selecting the effective methods for purifying the formaldehyde containing waste water is associated with an unstable composition, the deposition of condensates on the walls of containers and pipelines, changing the concentration of formaldehyde in the course of storage. The main reason for the difficulties associated with transportation and storage of waste water is determined by the content of water-soluble oligomers which may participate in the reactions of hydrolysis and polycondensation in aqueous solution. The maximum removal of water-soluble oligomers will simplify further purification and improve the operating conditions of the equipment. As a promising method for the removal of the aqueous phase oligomers formaldehyde resins can be regarded using of the compounds (polymers) capable to form insoluble products with them. Among the water-soluble polymers capable to form insoluble compounds with oligomers of urea-formaldehyde resins are of interest the lignosulfonic acid, which are the main component of large-tonnage by-product of sulphite pulp - technical lignosulfonates. In the technical lignosulfonates lignosulphonic acids are present as salts, preferably in the form of Na-salt.