A method for synergistic enhancement of phosphorus release from residual sludge using potassium persulfate and EDTA

Abstract

This invention relates to the field of wastewater treatment and resource utilization technology, and particularly to a method for synergistically enhancing phosphorus release from residual sludge using potassium persulfate and EDTA. The method involves mixing potassium persulfate and EDTA, adding the mixture to the residual sludge, stirring, and then filtering to obtain a phosphorus-containing supernatant. This invention utilizes potassium persulfate and EDTA to treat sludge under ambient temperature conditions, achieving a relatively low energy consumption while further improving the phosphorus release efficiency from the residual sludge. Simultaneously, as the sludge cell walls rupture, a large amount of water is released from the sludge, significantly reducing its water content and thus lowering sludge treatment costs.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment and resource utilization technology, and in particular to a method for synergistic enhancement of phosphorus release from residual sludge using potassium persulfate and EDTA. Background Technology

[0002] Sludge is a collective term for microbial communities and the inorganic and organic matter they adhere to, concentrating large amounts of phosphorus during wastewater treatment. With the increasing scarcity of phosphate rock resources, the phosphorus resources in sludge have gradually attracted researchers' attention. Total phosphorus in waste sludge can be divided into inorganic phosphorus and organic phosphorus. Studies have indicated that most phosphorus exists within organisms; therefore, it is necessary to release phosphorus from sludge for further recycling. Current research reports that phosphorus release technologies from waste sludge mainly include hot water hydrolysis, combined hot water hydrolysis and acid-base dosing treatment, anaerobic digestion, and ultrasonic treatment. 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 this invention is to address the aforementioned shortcomings of the prior art by proposing a method for synergistic enhancement of phosphorus release from residual sludge using potassium persulfate and EDTA.

[0004] The present invention discloses a method for synergistic enhancement of phosphorus release from residual sludge by potassium persulfate and EDTA, wherein potassium persulfate and EDTA are mixed, added to residual 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 residual sludge is 5-20 mmol / L.

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

[0008] Further, stir at room temperature.

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

[0010] Furthermore, the solids content of the remaining sludge is 1% to 2%.

[0011] Furthermore, the specific filtration operation involves using a 0.45μm aqueous filter membrane for vacuum filtration.

[0012] In this invention, EDTA (ethylenediaminetetraacetic acid) can chelate metal ions in sludge flocs and precipitates, causing sludge floc decomposition and thus destroying the sludge cell structure. This releases various substances in the sludge, which is beneficial for the oxidation effect of potassium persulfate on sludge and improves the sludge dismantling effect. At the same time, potassium persulfate can also convert organic phosphorus in the dismantled sludge into inorganic phosphorus. The carboxyl groups in EDTA have strong electrostatic and hydrogen bond interactions with inorganic phosphorus, which can better release phosphorus from the sludge and is conducive to the high-value application of phosphorus resources in the future.

[0013] This invention utilizes potassium persulfate in conjunction with EDTA to treat sludge at room temperature, thereby improving the phosphorus release efficiency in the residual sludge with relatively low energy consumption. At the same time, as the sludge cell walls rupture, a large amount of water is released from the sludge, significantly reducing the water content of the sludge and thus helping to lower the sludge treatment cost. Attached Figure Description

[0014] Figure 1 This is a comparison chart showing the phosphorus release effect of different concentrations of EDTA on the treatment of residual sludge according to the present invention.

[0015] Figure 2 This is a comparison chart showing the phosphorus release effect of different concentrations of potassium persulfate on the treatment of residual sludge according to the present invention.

[0016] Figure 3 This is a comparison chart showing the effect of different stirring times on phosphorus release in the treatment of residual sludge according to the present invention. Detailed Implementation

[0017] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings. However, the present invention is not limited to these embodiments.

[0018] Example 1:

[0019] S1. Take 100 ml of well-mixed residual sludge with a solid content of 1% into the reactor, and weigh out 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 hour.

[0021] S3. The remaining sludge after filtration is treated using a 0.45μm aqueous filter membrane to obtain a phosphorus-containing filtrate.

[0022] Example 2:

[0023] S1. Take 100 ml of well-mixed residual sludge with a solid content of 1% into the reactor, and weigh out 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 hour.

[0025] S3. The remaining sludge after filtration is treated using a 0.45μm aqueous filter membrane to obtain a phosphorus-containing filtrate.

[0026] Example 3:

[0027] S1. Take 100 ml of well-mixed residual sludge with a solid content of 1% into the reactor, and weigh out 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 hour.

[0029] S3. The remaining sludge after filtration is treated using a 0.45μm aqueous filter membrane to obtain a phosphorus-containing filtrate.

[0030] Example 4:

[0031] S1. Take 100 ml of well-mixed residual sludge with a solid content of 1% into the reactor, and weigh out 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 hours.

[0033] S3. The remaining sludge after filtration is treated using a 0.45μm aqueous filter membrane to obtain a phosphorus-containing filtrate.

[0034] Example 5:

[0035] S1. Take 100 ml of well-mixed residual sludge with a solid content of 1% into the reactor, and weigh out 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. The remaining sludge after filtration is treated using a 0.45μm aqueous filter membrane to obtain a phosphorus-containing filtrate.

[0038] Comparative Example 1:

[0039] S1. Take 100 ml of well-mixed residual sludge with a solid content of 1% and put it into the reactor.

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

[0041] S3. The remaining sludge after filtration is treated using a 0.45μm aqueous filter membrane 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% into the reactor, and 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 hour.

[0045] S3. The remaining sludge after filtration is treated using a 0.45μm aqueous filter membrane 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% into the reactor, and 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 hour.

[0049] S3. The remaining sludge after filtration is treated using a 0.45μm aqueous filter membrane 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% into the reactor, and 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 hour.

[0053] S3. The remaining sludge after filtration is treated using a 0.45μm aqueous filter membrane 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% into the reactor, and 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 hour.

[0057] S3. The remaining sludge after filtration is treated using a 0.45μm aqueous filter membrane 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% into the reactor, and 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 hour.

[0061] S3. The remaining sludge after filtration is treated using a 0.45μm aqueous filter membrane 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% into the reactor, and weigh out 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 hour.

[0065] S3. The remaining sludge after filtration is treated using a 0.45μm aqueous filter membrane 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% into the reactor, and weigh out 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. The remaining sludge after filtration is treated using a 0.45μm aqueous filter membrane to obtain a phosphorus-containing filtrate.

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

[0071] Table 1 Comparison of phosphorus concentration in supernatant of examples and comparative examples.

[0072] example Phosphorus concentration in supernatant (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 This is a comparison of the phosphorus release effect of different concentrations of EDTA on the treatment of residual sludge according to the present invention. The concentration of potassium persulfate added was fixed at 0 mmol / L, and the stirring time was 1 h. As shown in the figure, the optimal concentration of EDTA is 15 mmol / L.

[0074] Figure 2 This figure shows a comparison of the phosphorus release effects of different concentrations of potassium persulfate on the treatment of residual sludge. The concentration of EDTA added was fixed at 15 mmol / L, and the stirring time was 1 hour. As shown in the figure, the optimal concentration of potassium persulfate was 10 mmol / L.

[0075] Figure 3This is a comparison chart showing the effect of different stirring times on phosphorus release from the treatment of residual sludge according to the present invention. The concentration of potassium persulfate was fixed at 10 mmol / L, and the concentration of EDTA was fixed at 15 mmol / L. The optimal stirring time was 2 hours.

[0076] For any points not covered above, existing technologies shall apply.

[0077] Although specific embodiments of the present invention have been described in detail by way of examples, those skilled in the art should understand that the above examples are for illustrative purposes only and are not intended to limit the scope of the invention. Those skilled in the art can make various modifications or additions to the described specific embodiments or use similar methods to replace them, without departing from the direction of the invention or exceeding the scope defined by the appended 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 within the protection scope of the present invention.

Claims

1. A method for synergistically enhancing phosphorus release from excess sludge by potassium persulfate and EDTA, characterized in that: Potassium persulfate is mixed with EDTA, and then added into the residual sludge, stirred and filtered to obtain supernatant containing phosphorus; The molar ratio of the potassium persulfate to the EDTA is 1-4:3; The molar volume ratio of the potassium persulfate to the residual sludge is 5-20 mmol / L; The molar volume ratio of the EDTA to the residual sludge is 3-15 mmol / L; Stirring is carried out at room temperature. The stirring time is 1-3 h.

2. A method for synergistic enhancement of phosphorus release from excess sludge by potassium persulfate and EDTA according to claim 1, characterized in that: The residual sludge has a solid content of 1%-2%.

3. A method for synergistic enhancement of phosphorus release from excess sludge by potassium persulfate and EDTA as claimed in claim 1, wherein: The specific operation of the filtration is that the filtration is carried out by using a 0.45 μm water-based filter membrane.

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