Low-temperature thermal activation coupling H5IO6 synergistic reinforced dehydration method

Abstract

The invention discloses a low-temperature thermal activation coupling H5IO6 synergistic reinforced dehydration method, which comprises the following steps: 1) adding activated sludge to be treated into a beaker containing deionized water, and then heating to a set low temperature under a stirring condition; (2) adding H5IO6 into the sludge solution in the step (1), reacting under the condition of continuously stirring, and finishing the sludge dewatering process after the reaction is finished; and 3) filtering the reacted material in the step 2), and evaluating the activated sludge dewatering effect of the obtained filter cake, the synergistic reaction method constructed by the method provided by the invention significantly increases the generation speed of hydroxyl free radicals, effectively breaks the extracellular polymeric substance wrapping, breaks through the energy consumption bottleneck of traditional high-temperature dewatering, and has low temperature lt in the whole process; the risk of heavy metal dissolution is avoided, a new path is opened up for municipal sludge recycling, and the method is suitable for sludge co-treatment of a sewage treatment plant and promotes the industry to be transformed to be green and low-carbon.

Description

Technical Field

[0001] The present invention belongs to the technical field of sludge dewatering, and particularly relates to a synergistic enhanced dewatering method coupling low-temperature thermal activation with H5IO6. Background Art

[0002] With the rapid development of urbanization and industrialization, the discharge of domestic sewage and industrial wastewater has increased sharply. Excess activated sludge is a by-product of sewage treatment. The water content of these sludges generally reaches as high as 99%, and they contain a large amount of harmful substances such as organic matter, heavy metals, and pathogens. If not properly treated, it will cause serious environmental pollution. Extracellular polymeric substances (EPS) are negatively charged hydrophilic macromolecular polymers present in sludge, composed of proteins (PN), polysaccharides (PS), humus, etc. Traditional dewatering technologies can only reduce the water content to about 80%, resulting in a sharp increase in transportation and disposal costs. Therefore, developing an efficient sludge conditioning pretreatment process is the key to strengthening sludge dewatering at present.

[0003] In recent years, the method of using advanced oxidation processes to generate hydroxyl radicals to promote sludge dewatering has attracted great attention. By using the strong oxidizing property of oxidants to condition the sludge and break the colloidal structure of the sludge, the extracellular polymeric substances on the surface of the sludge flocs are oxidized, reducing the negative charge on the surface of the sludge colloid, reducing the repulsion of the double electric layer, reducing the steric hindrance between particles, and promoting the mutual impact between particles, thereby improving the sludge flocculation and enhancing the sludge dewatering performance. In traditional advanced oxidation processes, the ·OH generated by the Fenton system has a short half-life, is strictly required for pH conditions, and easily generates iron sludge, causing a treatment burden.

[0004] Therefore, the dewatering process of oxidants synergistically combined with other auxiliary technologies has begun to attract great attention. The present application proposes a green and efficient method for promoting sludge dewatering. Summary of the Invention

[0005] In view of the problems existing in the prior art, the purpose of the present invention is to provide a synergistic enhanced dewatering method coupling low-temperature thermal activation with H5IO6, which makes full use of the strong oxidation characteristics and acidic conditions of H5IO6, couples with the low-temperature thermal activation effect, significantly improves the solid-liquid separation characteristics of the sludge, can significantly reduce the sludge specific resistance, and effectively avoids the risk of secondary pollution caused by traditional processes while optimizing the dewatering performance.

[0006] To achieve the above purpose, the technical solution of the present invention is as follows: [[ID=Z3]] A synergistic enhanced dewatering method coupling low-temperature thermal activation with H5IO6, comprising the following steps: 1) Add the activated sludge to be treated into a beaker containing deionized water, and then heat it to a set low temperature under stirring conditions; 2) Add H5IO6 to the sludge solution in step 1), and carry out the reaction under continuous stirring. After the reaction ends, the sludge dehydration process is completed.

[0007] Further, it includes step 3) filtering the material after the reaction in step 2), and evaluating the dewatering effect of the activated sludge on the obtained filter cake.

[0008] Further, in step 1), the concentration of the activated sludge is 15 - 16 g / L, and the stirring speed is 200 - 300 r / min.

[0009] Further, in step 1), the set low temperature is 25 - 85°C.

[0010] Further, in step 1), the set low temperature is 70°C.

[0011] Further, in step 2), the concentration of H5IO6 is 100 - 800 mg / g DS.

[0012] Further, in step 2), the concentration of H5IO6 is 400 - 600 mg / g DS.

[0013] Further, in step 3), a conventional Buchner funnel is used to evaluate the dewatering effect of the activated sludge.

[0014] The reaction mechanism of the present invention is as follows: The present invention utilizes periodic acid in the +7 valence state as a highly efficient oxidant, and effectively cracks the extracellular polymer of the sludge through its strong oxidation effect, promoting the conversion of bound water to the free state. During the reaction, the controlled decomposition of H5IO6 can directionally generate various active oxygen species such as molecular oxygen (O2), singlet oxygen ( 1 O2) and hydroxyl radicals (·OH), which cooperate with low-temperature thermal activation to promote the compression of the electric double layer on the surface of colloidal particles and the neutralization of the Zeta potential, realizing the efficient coagulation and sedimentation of sludge particles.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: 1) The present invention uses the strong oxidizing property of H5IO6 (oxidation potential 1.6 V) to destroy the sludge EPS and microbial membrane structure, release capillary bound water and intracellular water. At the same time, the acidic condition (pH value 3.0 - 5.0) neutralizes the negative charge on the surface of the sludge colloid, reduces the electric double layer repulsion force, and promotes floc aggregation; 2) The present invention makes full use of the strong oxidation characteristics and acidic conditions of H5IO6, and couples with the low-temperature thermal activation effect to creatively propose a new method for promoting sludge dewatering by combining low-temperature heating with H5IO6. The newly constructed synergistic reaction finds a new green and efficient way for the dewatering of excess sludge. The synergistic reaction method constructed by the method of the present invention significantly improves the generation rate of hydroxyl radicals, effectively breaks through the extracellular polymer coating. This technology breaks through the energy consumption bottleneck of traditional high-temperature dewatering, and the whole process of low-temperature (<80°C) operation avoids the risk of heavy metal dissolution, opens up a new path for the resource utilization of municipal sludge, is applicable to the co-disposal of sewage treatment plant sludge, and promotes the industry to transform towards green and low-carbon; 3) During the reaction process, the controlled decomposition of H5IO6 can be directed to generate molecular oxygen (O2), singlet oxygen ( 1 O2) and hydroxyl radicals (·OH) and other polymorphic reactive oxygen species, which synergistically act with low-temperature thermal activation to promote the compression of the electric double layer on the surface of colloidal particles and the neutralization of the Zeta potential, realizing the efficient coagulation and sedimentation of sludge particles. This synergistic system significantly improves the solid-liquid separation characteristics of sludge, can significantly reduce the sludge specific resistance, and effectively avoids the risk of secondary pollution caused by traditional processes while optimizing the dewatering performance; 4) The present invention uses low-temperature heating combined with H5IO6 to strengthen sludge dewatering, realizes efficient solid-liquid separation of sludge, and has a high oxidation efficiency; H5IO6 is in a stable crystalline state at room temperature and is safe for transportation; the method of the present invention can be widely applied to the treatment and disposal of excess activated sludge in sewage treatment plants, and has obvious social and environmental benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 shows the influence of different heating temperatures on the sludge dewatering performance; Figure 2 shows the influence of different concentrations of periodic acid on the sludge dewatering performance; Figure 3 shows the influence of different conditioning systems on the sludge dewatering performance.

[0017] Note: RS is the original sludge. DETAILED DESCRIPTION OF THE INVENTION

[0018] The present invention will be further described below with reference to the drawings and embodiments, but the scope protected by the invention is not limited to the described scope.

[0019] Source and characteristic parameters of activated sludge The original activated sludge solution was taken from the secondary sedimentation tank of Shishan Wastewater Treatment Plant in Deqing County. After the original sludge was naturally settled for 4 h, the supernatant was drained off. It was treated with a laboratory standard sieve (1 mm), stored in a constant temperature refrigerator at 4 °C (storage period ≤ 14 d), and adjusted to the target concentration before use. The characteristic parameters of this activated sludge are as follows: the pH value is 6.7 ± 0.1; the total solid content (DS, %) is 1.59 ± 0.08; the volatile suspended solid content (g / g DS) is 0.56 ± 0.03; the sludge specific resistance (SRF, ×10 13 m / kg) is 4.20 ± 0.18; the time taken to filter to half of the sludge volume (TTF, s) is 40 ± 5; the moisture content (%) is 79.0 ± 0.5.

[0020] Example 1: Effect of different heating temperatures on sludge dewatering performance 100 mL of the activated sludge solution with a solid content of 16 g / L was respectively measured and placed in a 250 mL beaker. Under the action of a constant temperature magnetic stirrer, different heating temperatures were set for stirring reaction. The stirring speed was 200 r / min. 600 mg / g of periodic acid was added to the sludge solution in sequence and stirred until dissolved. The reaction was carried out for 30 min, and the stirring speed was 200 r / min. Finally, the sludge specific resistance (SRF) and sludge moisture content were measured by the conventional Buchner funnel method to evaluate the sludge dewatering performance. The set low-temperature heating temperatures were 25, 40, 55, 70, and 85 °C respectively.

[0021] It can be seen from Figure 1 that for the two parameters characterizing the sludge dewatering performance, the moisture content is lower when periodic acid and a heating temperature of 70 °C are used in combination, being 69.14%. As the temperature increases, the moisture content rises, and at a temperature of 85 °C, the moisture content deteriorates to 70.94%. The sludge specific resistance continuously decreases with the increase in temperature and also reaches the lowest at 70 °C and rises at 85 °C. Considering the economic benefits, and when the heating temperature is 70 °C, both the sludge specific resistance and the moisture content are relatively low. Therefore, the optimal heating condition for sludge treatment is 70 °C.

[0022] Example 2: Effect of different concentrations of periodic acid on sludge dewatering performance 100 mL of activated sludge solution with a solid content of 16 g / L was respectively measured and placed in a 250 mL beaker. Stirring reaction was carried out under the action of a constant temperature magnetic stirrer. The heating temperature was set at 70 °C, and the stirring speed was 200 r / min. Different doses of periodic acid were successively added to the sludge solution and stirred to dissolve. The reaction was carried out for 30 min with a stirring speed of 200 r / min. Finally, the sludge specific resistance (SRF) and sludge moisture content were measured by the conventional Buchner funnel method to evaluate the sludge dewatering efficiency. The addition amounts of the periodic acid were 100, 200, 300, 400, 500, 600, 700, 800 mg / g DS respectively calculated based on the solid content of the activated sludge.

[0023] It can be seen from Figure 2 that as the concentration of periodic acid increases, the moisture content continuously decreases, reaching the lowest value of 68.94% at a periodic acid concentration of 600 mg / g DS, and then starts to rise. The sludge specific resistance decreases significantly with the addition of periodic acid, but the change is basically unchanged with the increase of periodic acid concentration, and rises at 700 mg / g DS. Considering the economic benefits, and when the addition amount of periodic acid is 600 mg / g DS, both the sludge specific resistance and the moisture content are relatively low. Therefore, the optimal addition concentration of periodic acid is 600 mg / g DS.

[0024] Example 3: Optimal conditions for activated sludge dewatering 100 mL of activated sludge solution with a solid content of 16 g / L was measured and placed in a 250 mL beaker. Stirring reaction was carried out under the heating condition of 70 °C by a constant temperature magnetic stirrer, with a stirring speed of 200 r / min. H5IO6 with a dosage of 600 mg / g DS was added, and the stirring reaction was carried out for 30 min with a stirring speed of 200 r / min. Finally, the sludge specific resistance (SRF) and sludge moisture content were measured by the conventional Buchner funnel method to evaluate the sludge dewatering efficiency. It can be seen from Figure 3 that under these conditions, the moisture content and sludge specific resistance of the sludge are 68.94% and 0.83×10 13 m / kg respectively, and both the moisture content and the sludge specific resistance are the lowest. Therefore, these conditions are determined as the optimal conditions for activated sludge dewatering.

Claims

1. A synergistic enhanced dehydration method coupling low-temperature thermal activation with H5IO6, characterized by the following steps: 1) Add the activated sludge to be treated into a beaker containing deionized water, and then heat it to a set low temperature under stirring conditions; 2) Add H5IO6 to the sludge solution in step 1), and react under continuous stirring. After the reaction ends, the sludge dehydration process is completed.

2. The synergistic enhanced dehydration method coupling H5IO6 by low-temperature thermal activation according to claim 1, wherein It includes step 3) Filter the material after the reaction in step 2), and evaluate the dehydration effect of the obtained filter cake on the activated sludge.

3. A synergistic enhanced dehydration method coupling low-temperature thermal activation with H5IO6 according to claim 1, characterized in that In step 1), the concentration of the activated sludge is 15 - 16 g / L, and the stirring speed is 200 - 300 r / min.

4. A synergistic enhanced dehydration method coupling H5IO6 with low-temperature thermal activation according to claim 1, characterized in that In step 1), the set low temperature is 25 - 85 °C.

5. A synergistic enhanced dehydration method coupling H5IO6 by low-temperature thermal activation according to claim 4, characterized in that In step 1), the set low temperature is 70 °C.

6. The synergistic enhanced dehydration method coupling H5IO6 by low-temperature thermal activation according to claim 1, characterized in that In step 2), the concentration of H5IO6 is 100 - 800 mg / g DS.

7. A synergistic enhanced dehydration method coupling low-temperature thermal activation with H5IO6 according to claim 6, characterized in that In step 2), the concentration of H5IO6 is 400 - 600 mg / g DS.

8. The synergistic enhanced dehydration method coupling H5IO6 by low-temperature thermal activation according to claim 2, wherein In step 3), a conventional Buchner funnel is used to evaluate the dehydration effect of the activated sludge.

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