RU2129533C1 - Method of treatment of slime lignin - Google Patents

Abstract

FIELD: treatment of sewage water sediments, in particular, slime lignin of wood-pulp and paper industry. SUBSTANCE: method includes treatment of slime lignin with flocculant, water-repelling agent, and dewatering. Water-repelling agent is used in the form of ammonium salt and octylbetathiopropionic acid. Due to increased water loss of sediments and reduced dwell time of sediments on dewatering stage efficiency of vacuum filters, filter presses, flotation machines increases. EFFECT: higher efficiency. 2 tbl

Description

 The invention relates to the field of sewage sludge treatment, in particular lignin sludge from the pulp and paper industry, and can also be used in chemical, hydrolysis and other industries, where sludge treatment is one of the most difficult, costly and least developed problems.

 A known method of preparing sludge for dehydration by mechanical methods (on vacuum filters, on filter presses) using as chemical reagents for coagulation of ferric chloride, ferrous sulfate and other reagents in combination with lime [Turovsky I.S. Wastewater sludge treatment. M., Stroyizdat, 1975, p.21-42].

 In the pulp and paper industry, the formation of sludge properties begins at the stage of wastewater treatment, including coagulant treatment with aluminum sulfate. The amount of sludge - sludge-lignin with a moisture content of 99.7-99.8% is 7-10% of the treated wastewater. A known method of treating sludge, in particular sludge-lignin for chemical treatment of pulp and paper industry, with flocculants followed by mechanical dehydration (Altovsky G.S. Current status and main directions of development of wastewater sludge treatment technology. Soviet-American symposium on wastewater sludge treatment. M., 1975, S. 5-15]. The disadvantages of the method include the poor yield of sludge during subsequent mechanical dehydration and, as a consequence, the high humidity of the sludge.

 To increase water loss, it is necessary to change the structure of the solid phase of precipitation. A change in the structure leads to a quantitative redistribution of moisture bond forms towards an increase in the content of free water due to a decrease in the total amount of bound water. Such a change in the structure of sediments allows for a deeper and faster dehydration.

 The closest in technical essence and the achieved result is a method of processing sludge, in particular sludge-lignin, which includes treating with a coagulant, flocculant and reagent a hydrophobizing agent ANP-2 with subsequent mechanical or flotation dehydration [USSR Author's Certificate N 1061411, cl. C 02 F 11/14 (prototype)]. This method is implemented at the Baikal Pulp and Paper Mill.

 Due to the limited production and, in particular, the complexity of the supply of ANP-2, as well as its relatively high toxicity, a search and targeted synthesis of less toxic and more effective hydrophobizing reagents is underway.

 The present invention solves the problem of reducing the moisture content of the sediment by increasing its water loss.

This goal is achieved by the fact that in the method of processing sludge-lignin, including treatment with a flocculant, a hydrophobizing agent and dehydration, the ammonium salt of octyl betatiopropionic acid of the formula C ₈ H ₁₇ SCH ₂ CH ₂ COONH _{4 is} used as a hydrophobizing agent.

The use of the ammonium salt of octyl betatiopropionic acid of the formula C ₈ H ₁₇ SCH ₂ CH ₂ COONH ₄ as a water repellent is a difference from the prototype, which makes the claimed technical solution meet the criterion of "novelty."

The use of octyl betatiopropionic acid ammonium salt containing a long chain alkyl radical C ₈ H ₁₇ as a hydrophobizing reagent, on the one hand, will improve the process of hydrophobization of the surface of the precipitate particles, and on the other, due to the presence of the S atom, COONH ₄ group provides better adsorption of the reagent on the surface of the sediment with the formation of a durable hydrophobic layer. There is a quantitative redistribution of the forms of water bonds in the direction of increasing the content of free water due to a decrease in the total amount of capillary bound water. This targeted change in sludge structure allows for deeper dehydration.

 The use of octylbetathiopropionic acid ammonium salt as a water repellent was not found in the scanned scientific, technical and patent literature, namely, its use allows to increase the yield of sludge, reduce its moisture content and, thus, increase the efficiency of dehydration. This indicates the conformity of the claimed technical solution to the criterion of "inventive step".

 The method is as follows. The precipitate of chemically purified wastewater sludge-lignin is treated with a hydrophobizing reagent with ammonium salt of octyl betatiopropionic acid and a flocculant. Then, lignin sludge is sent for mechanical or flotation dehydration (filter presses, vacuum filters, centrifuges, flotation chambers).

The ammonium salt of octyl betatiopropionic acid was obtained by the method described previously [B. Trofimov. Vavilova A.N., Borodina N.M. "Sulfur Letters, volume 4, June 1986, p. 185-190], by the interaction of octyl mercaptan C ₈ H ₁₇ SH with acrylic acid H ₂ C = CHCOOH in the presence of potassium hydroxide and dimethyl sulfoxide, followed by treatment with liquid ammonia. The temperature did not exceed 50-55 ^o C, reaction time 4 hours, quantitative yield of ammonium salt 70%. The structure is proved by elemental analysis and IR spectroscopy. C ₁₁ H ₂₅ O ₂ SN. Calculated,%: C 56.13; H 10.71; S 13 62; N 5.95. Found,%: C 56.67; H 10.80; S 13.50; N 5.88. IR spectrum, cm ^-1 : 1710-1720 (VС = O).

 The reagent is practically non-toxic, a lethal dose of LD-300 mg / kg.

 Example 1. A sample of sludge-lignin from the sludge processing plant of the Baikal Pulp and Paper Mill (aluminum sulfate consumption by aluminum ion of 18.4 mg / l; absolutely dry matter content of 3.5 g / l; pH of the medium 5.8) is treated with a flocculant polyacrylamide ( PAA) at a rate of 0.38 mg / L. After two hours of contact, the sample is filtered through a paper filter.

 Example 2. A sample of sludge-lignin with the same characteristics as in example 1 is treated first with an ANP-2 hydrophobizing agent in an amount of 80 mg / l, the solution concentration is 1% and then PAA is added at a rate of 0.38 mg / l. After two hours of contact, the sample is filtered through a paper filter.

 Example 3. A sample of sludge-lignin with the same characteristics as in example 1 is first treated with a hydrophobizing reagent with ammonium salt of octyl betatiopropionic acid in an amount of 80 mg / l, the concentration of the solution is 1% and then PAA is added at a rate of 0.38 mg / l . After two hours of contact, the sample is filtered through a paper filter.

 Comparative results with the prototype dehydration of sludge-lignin are shown in table 1.

 As can be seen from the table, the filtration rate according to the proposed method increases in comparison with the filtration results with the processing of ANP-2 in 1.7-1.99 times. According to the proposed method, after 9 minutes of filtering the precipitate, the filtrate volume reaches a maximum value of 97 ml, while according to the prototype after 15 minutes the filtrate volume is 93 ml.

Example 4. A sample of sludge-lignin from the sludge processing shop of the Baikal Pulp and Paper Mill with a concentration of suspended solids of 3.5 g / l was saturated with air at a pressure of 0.2 MPa. Then they were treated with PAA flocculant with a flow rate of 0.38 mg / L and reagents ANP-2 and C ₈ H ₁₇ SCH ₂ CH ₂ COONH _{4 were} added with a flow rate of 2-8 g / kg, the concentration of the reagent solution was 1%. The results of dehydration of sludge-lignin by pressure flotation are shown in table 2.

 As can be seen from the table, with the introduction of a new reagent gidrofobizator achieved better results and flotation dehydration of sludge-lignin in comparison with the prototype. So, the speed of flotation dehydration, expressed through the rate constant, according to the proposed method increases by 1.6-2.0 times. The advantage of the proposed reagent is preserved at lower costs (2-4 g / kg). Moreover, at any doses of the new reagent, clarified water contains less suspended solids than when using ANP-2.

 The increase in the speed of flotation dehydration makes it possible to reduce the residence time of sludge-lignin in the flotation chamber, which will significantly increase the productivity of flotation machines. The proposed reagent is non-toxic and is characterized by the simplicity of synthesis (one-step synthesis), the availability of starting reagents, the possibility of organizing production at the enterprises of the Irkutsk region and can be successfully used as an effective water repellent instead of ANP-2 for filtration and flotation dehydration of sludge-lignin.

Claims (1)

 A method of treating sludge-lignin, including treatment with a flocculant, a hydrophobizing agent and dehydration, characterized in that the ammonium salt of octyl betatiopropionic acid is used as a hydrophobizing agent.

Images