Method for synergistically enhancing phosphorus release of excess sludge by potassium persulfate and EDTA (Ethylene Diamine Tetraacetic Acid)

Abstract

The invention relates to the technical field of sewage treatment and resource utilization, in particular to a method for synergistically enhancing phosphorus release of excess sludge by potassium persulfate and EDTA (Ethylene Diamine Tetraacetic Acid). According to the method for synergistically enhancing phosphorus release of the excess sludge through potassium persulfate and EDTA, potassium persulfate and EDTA are mixed, added into the excess sludge, stirred and filtered, and phosphorus-containing supernate is obtained. According to the method, potassium persulfate and EDTA are used for treating sludge under the normal temperature condition, the release efficiency of phosphorus in excess sludge is further improved with relatively low energy consumption, meanwhile, along with rupture of cell walls of the sludge, a large amount of water in the sludge is released, the water content of the sludge is greatly reduced, and the treatment cost of the sludge is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of sewage treatment and resource utilization, and in particular to a method for enhancing the release of phosphorus from excess sludge in a coordinated manner using potassium persulfate and EDTA. Background Art

[0002] Sludge is a general term for microbial communities and the inorganic and organic matter they are attached to. It concentrates a large amount of phosphorus during the sewage treatment process. As phosphate rock resources become increasingly scarce, phosphorus resources in sludge have gradually attracted the attention of researchers. The total phosphorus in residual sludge can be divided into inorganic phosphorus and organic phosphorus. Studies have shown that most of the phosphorus exists in organisms. Therefore, it is necessary to release the phosphorus in the sludge for further recycling. In current research reports, the main technologies for releasing phosphorus from residual sludge include thermal hydrolysis, thermal hydrolysis and acid-base addition combined treatment, anaerobic digestion, ultrasonic treatment, etc. However, these technologies are difficult to use on a large scale due to high operating costs and complex processes. Summary of the invention

[0003] The purpose of the present invention is to address the above-mentioned deficiencies in the prior art and to provide a method for enhancing the release of phosphorus from excess sludge by synergistically combining potassium persulfate and EDTA.

[0004] The invention discloses a method for enhancing phosphorus release of excess sludge by synergistically using potassium persulfate and EDTA. Potassium persulfate and EDTA are mixed, added into excess sludge, stirred, and then filtered to obtain a phosphorus-containing supernatant.

[0005] Furthermore, the molar ratio of potassium persulfate to EDTA is 1 to 4:3.

[0006] Furthermore, the molar volume ratio of potassium persulfate to excess sludge is 5-20 mmol / L.

[0007] Furthermore, the molar volume ratio of EDTA to excess sludge is 3-15 mmol / L.

[0008] Further, stirring is performed at room temperature.

[0009] Furthermore, the stirring time is 1-3h.

[0010] Furthermore, the solid content of the residual sludge is 1% to 2%.

[0011] Furthermore, the specific operation of filtration is to use a 0.45 μm water filter membrane for suction filtration.

[0012] In the present invention, EDTA (ethylenediaminetetraacetic acid) can chelate metal ions in sludge flocs and sediments, causing decomposition of sludge flocs, thereby destroying the sludge cell structure, and can release various substances in the sludge, which is beneficial to the oxidation effect of potassium persulfate on the sludge and improving the sludge breaking effect. At the same time, potassium persulfate can also convert organic phosphorus in the broken sludge into inorganic phosphorus. The carboxyl group in EDTA has strong electrostatic and hydrogen bond interactions with inorganic phosphorus, which can better release phosphorus in the sludge, and is beneficial to the subsequent high-value application of phosphorus resources.

[0013] The present invention utilizes potassium persulfate in conjunction with EDTA to treat sludge at room temperature, thereby further improving the release efficiency of phosphorus in excess sludge with relatively low energy consumption. At the same time, as the sludge cell walls are broken, a large amount of water in the sludge is released, and the water content of the sludge is greatly reduced, which is beneficial to reducing the treatment cost of the sludge. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a comparison chart of the phosphorus release effects of different concentrations of EDTA on excess sludge treatment in the present invention.

[0015] Figure 2 This is a comparison chart of the phosphorus release effects of different concentrations of potassium persulfate on excess sludge treatment in the present invention.

[0016] Figure 3 This is a comparison chart of the phosphorus release effect of different stirring times on excess sludge treatment in the present invention. DETAILED DESCRIPTION

[0017] The following are specific embodiments of the present invention and the accompanying drawings to further describe the technical solution of the present invention, but the present invention is not limited to these embodiments.

[0018] Embodiment 1:

[0019] S1. Take 100 ml of well-mixed residual sludge with a solid content of 1% in a reactor, weigh potassium persulfate (10 mmol / L) and EDTA (15 mmol / L) and add them to the residual sludge.

[0020] S2. Stir the mixture in the reactor at room temperature for 1 h.

[0021] S3. Use a 0.45 μm water filter membrane to filter the remaining sludge after treatment to obtain a phosphorus-containing filtrate.

[0022] Embodiment 2:

[0023] S1. Take 100 ml of well-mixed residual sludge with a solid content of 1% in a reactor, weigh potassium persulfate (15 mmol / L) and EDTA (15 mmol / L) and add them to the residual sludge.

[0024] S2. Stir the mixture in the reactor at room temperature for 1 h.

[0025] S3. Use a 0.45 μm water filter membrane to filter the remaining sludge after treatment to obtain a phosphorus-containing filtrate.

[0026] Embodiment 3:

[0027] S1. Take 100 ml of well-mixed residual sludge with a solid content of 1% in a reactor, weigh potassium persulfate (20 mmol / L) and EDTA (15 mmol / L) and add them to the residual sludge.

[0028] S2. Stir the mixture in the reactor at room temperature for 1 h.

[0029] S3. Use a 0.45 μm water filter membrane to filter the remaining sludge after treatment to obtain a phosphorus-containing filtrate.

[0030] Embodiment 4:

[0031] S1. Take 100 ml of well-mixed residual sludge with a solid content of 1% in a reactor, weigh potassium persulfate (10 mmol / L) and EDTA (15 mmol / L) and add them to the residual sludge.

[0032] S2. Stir the mixture in the reactor at room temperature for 2 h.

[0033] S3. Use a 0.45 μm water filter membrane to filter the remaining sludge after treatment to obtain a phosphorus-containing filtrate.

[0034] Embodiment 5:

[0035] S1. Take 100 ml of well-mixed residual sludge with a solid content of 1% in a reactor, weigh potassium persulfate (10 mmol / L) and EDTA (15 mmol / L) and add them to the residual sludge.

[0036] S2. Stir the mixture in the reactor at room temperature for 3 hours.

[0037] S3. Use a 0.45 μm water filter membrane to filter the remaining sludge after treatment to obtain a phosphorus-containing filtrate.

[0038] Comparative Example 1:

[0039] S1. Take 100 ml of evenly mixed residual sludge with a solid content of 1% and place it in a reactor.

[0040] S2. Stir the mixture in the reactor at room temperature for 1 h.

[0041] S3. Use a 0.45 μm water filter membrane to filter the remaining sludge after treatment to obtain a phosphorus-containing filtrate.

[0042] Comparative Example 2:

[0043] S1. Take 100 ml of well-mixed residual sludge with a solid content of 1% and put it in a reactor. Weigh EDTA (3 mmol / L) and add it to the residual sludge.

[0044] S2. Stir the mixture in the reactor at room temperature for 1 h.

[0045] S3. Use a 0.45 μm water filter membrane to filter the remaining sludge after treatment to obtain a phosphorus-containing filtrate.

[0046] Comparative Example 3:

[0047] S1. Take 100 ml of well-mixed residual sludge with a solid content of 1% and put it in a reactor. Weigh EDTA (6 mmol / L) and add it to the residual sludge.

[0048] S2. Stir the mixture in the reactor at room temperature for 1 h.

[0049] S3. Use a 0.45 μm water filter membrane to filter the remaining sludge after treatment to obtain a phosphorus-containing filtrate.

[0050] Comparative Example 4:

[0051] S1. Take 100 ml of well-mixed residual sludge with a solid content of 1% and put it in a reactor. Weigh EDTA (9 mmol / L) and add it to the residual sludge.

[0052] S2. Stir the mixture in the reactor at room temperature for 1 h.

[0053] S3. Use a 0.45 μm water filter membrane to filter the remaining sludge after treatment to obtain a phosphorus-containing filtrate.

[0054] Comparative Example 5:

[0055] S1. Take 100 ml of well-mixed residual sludge with a solid content of 1% and put it in a reactor. Weigh EDTA (12 mmol / L) and add it to the residual sludge.

[0056] S2. Stir the mixture in the reactor at room temperature for 1 h.

[0057] S3. Use a 0.45 μm water filter membrane to filter the remaining sludge after treatment to obtain a phosphorus-containing filtrate.

[0058] Comparative Example 6:

[0059] S1. Take 100 ml of well-mixed residual sludge with a solid content of 1% and put it in a reactor. Weigh EDTA (15 mmol / L) and add it to the residual sludge.

[0060] S2. Stir the mixture in the reactor at room temperature for 1 h.

[0061] S3. Use a 0.45 μm water filter membrane to filter the remaining sludge after treatment to obtain a phosphorus-containing filtrate.

[0062] Comparative Example 7:

[0063] S1. Take 100 ml of well-mixed residual sludge with a solid content of 1% in a reactor, weigh potassium persulfate (5 mmol / L) and EDTA (15 mmol / L) and add them to the residual sludge.

[0064] S2. Stir the mixture in the reactor at room temperature for 1 h.

[0065] S3. Use a 0.45 μm water filter membrane to filter the remaining sludge after treatment to obtain a phosphorus-containing filtrate.

[0066] Comparative Example 8:

[0067] S1. Take 100 ml of well-mixed residual sludge with a solid content of 1% in a reactor, weigh potassium persulfate (10 mmol / L) and EDTA (15 mmol / L) and add them to the residual sludge.

[0068] S2. Stir the mixture in the reactor at room temperature for 0.5 h.

[0069] S3. Use a 0.45 μm water filter membrane to filter the remaining sludge after treatment to obtain a phosphorus-containing filtrate.

[0070] Phosphorus release rate (relative to sludge supernatant phosphorus concentration) = (S3 supernatant phosphorus concentration - original solution supernatant phosphorus concentration) / original solution supernatant phosphorus concentration * 100%

[0071] Table 1 Comparison of supernatant phosphorus concentration in Examples and Comparative Examples

[0072] example Supernatant phosphorus concentration (mg / L) Phosphorus release rate Example 1 127.22 510.2％ Example 2 118.13 466.6％ Example 3 120.20 476.5％ Example 4 136.25 553.4％ Example 5 135.24 548.6％ Comparative Example 1 20.85 100.0％ Comparative Example 2 63.00 202.2％ Comparative Example 3 98.12 370.5％ Comparative Example 4 106.17 409.2％ Comparative Example 5 109.16 423.5％ Comparative Example 6 113.41 443.9％ Comparative Example 7 114.18 447.6％ Comparative Example 8 99.12 375.8％

[0073] Figure 1 The figure is a comparison of the phosphorus release effect of different concentrations of EDTA on excess sludge treatment in the present invention. The fixed concentration of potassium persulfate added is 0mmol / L, and the stirring time is 1h. As shown in the figure, the optimal EDTA addition concentration is 15mmol / L.

[0074] Figure 2 The figure is a comparison chart of the phosphorus release effect of different concentrations of potassium persulfate on excess sludge treatment of the present invention. The fixed concentration of EDTA added is 15mmol / L, and the stirring time is 1h. As shown in the figure, the optimal addition concentration of potassium persulfate is 10mmol / L.

[0075] Figure 3The figure is a comparison of the phosphorus release effect of different stirring times on the excess sludge treatment of the present invention. The concentration of potassium persulfate added is fixed at 10mmol / L, the concentration of EDTA is 15mmol / L, and the optimal stirring time is 2h.

[0076] For matters not mentioned above, the prior art applies.

[0077] Although some specific embodiments of the present invention have been described in detail through examples, those skilled in the art should understand that the above examples are for illustration only and are not intended to limit the scope of the present invention. Those skilled in the art to which the present invention belongs may make various modifications or supplements to the specific embodiments described or replace them in a similar manner, but they will not deviate from the direction of the present invention or exceed the scope defined by the attached claims. Those skilled in the art should understand that any modifications, equivalent substitutions, improvements, etc. made to the above embodiments based on the technical essence of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for enhancing the release of phosphorus from excess sludge by synergistically using potassium persulfate and EDTA, characterized in that: Potassium persulfate and EDTA are mixed, added to the remaining sludge, stirred, and then filtered to obtain a phosphorus-containing supernatant.

2. The method for enhancing the release of phosphorus from excess sludge by synergistically using potassium persulfate and EDTA as claimed in claim 1, characterized in that: The molar ratio of potassium persulfate to EDTA is 1 to 4:

3.

3. The method for enhancing phosphorus release from excess sludge by synergistically using potassium persulfate and EDTA as claimed in claim 1, characterized in that: The molar volume ratio of the potassium persulfate to the excess sludge is 5-20 mmol / L.

4. The method for enhancing phosphorus release from excess sludge by synergistically using potassium persulfate and EDTA as claimed in claim 1, characterized in that: The molar volume ratio of the EDTA to the excess sludge is 3-15 mmol / L.

5. The method for enhancing the release of phosphorus from excess sludge by synergistically using potassium persulfate and EDTA as claimed in claim 1, characterized in that: Stir at room temperature.

6. The method for enhancing the release of phosphorus from excess sludge by synergistically using potassium persulfate and EDTA as claimed in claim 1, characterized in that: The stirring time is 1-3h.

7. The method for enhancing phosphorus release from excess sludge by synergistically using potassium persulfate and EDTA as claimed in claim 1, characterized in that: The solid content of the residual sludge is 1% to 2%.

8. The method for enhancing phosphorus release from excess sludge by synergistically using potassium persulfate and EDTA as claimed in claim 1, characterized in that: The specific operation of filtration is to use a 0.45 μm water filter membrane for suction filtration.

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