SU701959A1 - Method of decolorizing biologically purified waste water of cellulose-paper production - Google Patents

Description

The inventive process for the purification of waste water can be used to discolor the wastewaters of pulp and paper industry (pulp and paper industry). The sewage of pulp and paper enterprises is characterized by significant color, due to the presence of water-soluble lignin derivatives (lignosulfonic acids, alkaline lignin, chlorine lignin, etc.) that enter the sewage as a result of washing and bleaching pulp. When such wastes are discharged into the reservoir, the listed substances give its waters a color, an unpleasant smell and a taste not looking for a large dilution, which adversely affects the state of the fauna and flora. A known method of purification of wastewater from lignosulfonates. The method consists in the coprecipitation of lignosulfonates with such compounds as silicates, hydroxides, oxides, and hydrates of metal oxides of the II and III groups at pH 1-6. The method may include a second stage in which alkaline or alkaline earth metal compounds 1 are added to the reaction medium. The disadvantage of this method is that it is designed to remove only one lignin derivative, lignosulfonates. In addition, the known method involves the use of expensive reagents. A known method for bleaching alkaline wastewater that has undergone biological treatment, during which the easily acidic organic compounds are removed — BODV is reduced to 20–25 mg / l. The method of bleaching includes the sequential introduction of coagulant and flocculant, settling, neutralization with caustic soda, filtration and disinfection 2}. The main disadvantages of the discoloration of wastewater enterprises of pulp and paper industry in this way are the large capital and operating costs associated with the construction and maintenance of chemical reagents on the bleaching of runoff by chemical means. In addition, only sulfate-cellulose production containing alkaline lignin is bleached by this chemical method. Thus, when there is a drain, it contains .Jt 3. . # ro as alkaline lignin, lak and lignosuldacetic acids, as well as other products of lignin, which is the case in pulp and paper industry enterprises, is not achieved efficiently. The aim of the invention is to increase (the degree of discoloration, as well as the simplification and cheapening of the process. The goal is achieved by the inoculation of biologically purified waste waters from the bacteria of the genus ThiobaciMus with subsequent aeration to pH 1-5. the formation of sulfuric acid, which lowers the pH of the medium, which contributes to the precipitation of lignin derivatives in plantings. Sulfur-containing lignin derivatives, when treated with thionic bacteria, lose their sulfur, which additionally contributes to s), their precipitate. The source of energy for bacteria of the genus Thiobacillus is the reduced compounds 9 and sulfur, which are always present in the waste bottoms of the AEF enterprises. Subsequent neutralization of the resulting suspension to pH 6-7 does not lead to peptizaply precipitate, but significantly improves the flocculation process. . P and meer. Biologically purified wastewater of a pulp and paper mill, containing an irreproachable spectrum of water-soluble derivatives of lignin (lipusulfonic acids, alkaline lignin, hlligpin, etc.), with a dressiness of 1400. Bacteria of the genus Thiobacillus are inoculated and the pH of the PH is aerated. The bleached liquid is neutralized with ammonia solution to a pH of 6-7 and settled. The most technologically advanced for neutralization is the use of Ca (OH) 2. However, in order to exclude the influence of bivalent calcium ions on the results of bleaching, an ammonia solution is used. Comparative data is given in the table.