SU990682A1 - Method for recovering aluminium-containing coagulant from water purification sludge - Google Patents

Description

The invention relates to the purification of natural waters, in particular to the regeneration of aluminum-containing coagulant used to purify them.

In purification of natural waters for use in power equipment, hydrogen-cation filters are used, sorbing the Ca, Md and Ha cations contained in natural waters. During operation, it is necessary to restore the sorption capacity of hydrogen-cation-resin filters, which is carried out with an acid solution, resulting in a significant amount of wastewater that is dangerous to the environment and has not been used up to date.

For the purification of natural waters from suspended and colloidal particles, aluminum-containing coagulants are used (А 1 (50), A1С1з, etc.). Their use leads to the formation of large

the amount of sludge that is up to 10 or more by volume from the treated water. The sludge has a moisture content of 98.7-99, P.

Loss on ignition was 5–37–55.

The calcinated residue,%: SIOz- 5,6-27; R Oh, - - 17-39,7; AV | 03 16, 6-33.3; Fe2.or-0.6-6; CaO - 9,129, 5; R bj / SiOa. - 0, bz-, 5. 10 Aluminum compounds are recovered from this slurry for reuse as coagulant.

A known method for extracting aluminum containing coagulant by treating the sludge with alkali 1.

The disadvantage of this method is the low quality of the coagulant produced, due to the presence of a significant amount of organic

20 substances passing into the solution simultaneously with the coagulant.

Claims (2)

The closest to the invention with the technical essence and the result achieved is the method of extracting and luting coagulum from the lines of water by treating with an acidic solution, which is used as a solution of sulfuric acid, starts at a pH, is accompanied by a decrease in sediment volume and a slow decrease in pH . The lower the pH, the more dissolving the process. At a pH of 2.5-3.0, the main part of the alumini hydroxide 23 in the sediment passes into the solution. However, simultaneously with the aluminum hydroxide, some of the organic substances contained in the sediment pass into the solution, the amount of which increases with increasing acid and lowering the pH. The disadvantages of this method are that the coagulum recovery rate is not high and the coagulation activity is insufficient. The purpose of the invention is to increase the recovery rate of the coagulant and increase its coagulation activity. The goal has been achieved by the method of extracting aluminum-containing coagulant from a water treatment sludge by treating it with an acidic solution, according to which wastewater is used as an acidic solution after washing the hydrogen-cation-exchange filters having the following composition, weight. %: K SQt0,2-0,8 CaS0420-25 MgS04 5-8 Na2.S043H, j5QiOther When using these waste waters as an extra agent, aluminum ions are transferred to the solution, the amount of which exceeds that which is formed using sulfuric acid . At the same time, ions of other metals contained in wastewater from wastewater also exhibit coagulation activity, which contributes to an increase in the activity of the regenerated coagulant. In addition, the interaction of wastewater hydrogen-cationite filters with water treatment sludge produces insoluble salts of organic acids present in the sludge, which precipitate and, therefore, only a small amount of organic matter is present in the coagulum solution. PRI me R. Aluminum-containing coagulant is regenerated from sludge formed during the coagulation of the water of the Severnaya Dvina river with a solution of A1 (50d). Waste water is used as an extractant for extracting aluminum-containing coagulant from water treatment sludge during the passage of sulfuric acid through a hydrogen-cation-exchange filter. After washing the filter, the wastewater with a total impurity content of 2% has the following composition,%. 0.2-0.8; CaS04 20-25; MgS04 S 8; (3-4 and the rest. Four experiments were carried out with sludge collected in different seasons of the year. During the experiments, 20 ml of sludge with a solid phase concentration of 2% were poured into iO ml of waste WATER; A significant part of the sludge is dissolved. The solution is separated from the precipitate by filtration or by settling. Next, the content of regenerated aluminum in the solution is determined by the standard photocolorimetric method with a stilbazo reagent, as well as the color of the coagulant by the photocolorimetric method and the permanganate oxidability of the coagulum. For comparison with the same sludge of steam A coagulant regeneration experiment was successfully carried out with a solution of sulfuric acid, after experimentally determining the optimal concentration and amount. 20 ml of sulfuric acid was poured into 20 ml of sludge. The subsequent processing and testing of the regenerated coagulant was carried out in a manner similar to that shown. Table 1. From Table 1 it follows that the amount of aluminum recovered by wastewater is greater than the amount of aluminum regenerated by acid, which means more complete echenie coagulant present extractants. In addition, the improvement of the physicochemical parameters of coagulant regenerated by sewage (chromaticity, oxidability) improves its quality. The activity of coagulant regenerated by sewage is checked by trial coagulation of the water of the Severnaya Dvina river. They spent four days in different seasons. To 500 ml of water was added a solution of coagulant regenerated with wastewater with a dose of A1 equal to 8 mg / l. In parallel, the same water was cleaned with coagulum obtained by regeneration with sulfuric acid with the same dose of aluminum. The comparative characterization of purified water by these two coagulants is given in Table. 2. From table. Figure 2 shows that the physicochemical indices of the quality of purified water are higher when using coagulums 9,826 and regenerated by sewage, which means its higher coagulation activity. Compared with the known method of extracting coagulant with sulfuric acid (for example, at the Northern Waterworks of Moscow), the proposed method gives a significant economic effect due to the use of a cheaper extractant. The economic effect on the water treatment facilities of the Arkhangelsk pulp and paper mill is about 251 thousand rubles. in year. Table 1 Claims 1. Invention method for removing aluminum-containing coagulant from water treatment sludge by treating with an acidic solution, characterized in that, in order to increase the degree of extraction and increase its coagulation activity, wastewater is used as an acidic solution after washing the hydrogen-cationite filters . 2. The method according to claim 1, about tl and h and u-. u and with the fact that the waste water after washing the hydrogen-cation filter has the following composition, weight. : 0,2-0,8 KoSO СаЗрф MgSb4. Na2.50f. The rest Sources of information taken into account during the examination 1. USSR Copyright Certificate No., cl. C 02 B 1/18, 1968. 2, Weizser Yu.I. and others. Coagulant regeneration from the sediments of water stations. - Water supply and sanitary equipment, 197, No. 1, p. 6-9.