Oxidation pretreatment method based on ozone / superphosphate and application thereof

Abstract

The invention discloses an oxidation pretreatment method based on ozone / superphosphate and application thereof.The method comprises the following steps that ozone and superphosphate are added into a drinking water source, the adding amount of the ozone is 2.0-5.0 mg / L, and the adding amount of the superphosphate is 5.0-10.0 mg / L; reacting for 5 to 10 minutes; and a final reaction product phosphate is removed through coagulation and precipitation processes. When the initial concentration of the smelly substances in the water is less than or equal to 100ng / L, the smelly substances can be reduced to be less than a smelly threshold value by applying the method, and water quality parameters such as total organic carbon, chromaticity and the like are not influenced. The ozone oxidation end product is oxygen, the phosphate end product is phosphate, the oxygen and the phosphate can be effectively removed through subsequent conventional water treatment processes (coagulation and precipitation), and the method has the advantages of being easy and convenient to operate, low in cost, environmentally friendly and the like and is suitable for pretreatment of various drinking water sources such as surface water and underground water.

Description

Technical Field

[0001] The present invention relates to water treatment, and in particular to an ozone / superphosphate-based oxidation pretreatment method and application thereof. Background Art

[0002] Odor-producing substances in drinking water sources (such as geosmin and 2-methylisoborneol) are primarily derived from algal metabolites, humic decomposition, and industrial pollution. Conventional water treatment processes (such as coagulation, sedimentation, and filtration) are inefficient in removing these substances, posing a challenge to drinking water safety. Advanced oxidation technologies (AOPs) have garnered significant attention in recent years due to their high efficiency, but existing technologies have the following shortcomings: 1. Ozone oxidation alone: This technology does not completely degrade large molecular odorous substances and requires high ozone concentrations (>5.0 mg / L), resulting in high costs. 2. Ozone / catalyst systems: These require the addition of metal catalysts, which may introduce heavy metals or make catalyst recovery difficult. 3. Persulfate activation technology: This technology relies on UV light or transition metal activation, consumes a lot of energy, and is prone to sulfate contamination. Summary of the Invention

[0003] Purpose of the invention: The purpose of the present invention is to provide an ozone / superphosphate-based oxidation pretreatment method for efficiently degrading odorous substances; another purpose of the present invention is to provide the application of this method in removing odorous substances from drinking water sources.

[0004] Technical solution: The ozone / superphosphate-based oxidation pretreatment method described in the present invention includes the following steps: simultaneously adding ozone and superphosphate to a drinking water source, with an ozone dosage of 2.0 to 5.0 mg / L and a superphosphate dosage of 5.0 to 10.0 mg / L; reacting for 5 to 10 minutes; and finally removing the reaction end product, phosphate, through coagulation and precipitation processes.

[0005] Ozone reacts with superphosphate to generate phosphate radicals (·PO4 2 -), and work together with ozone to degrade odorous substances; the final product of ozone is oxygen, and the final product of superphosphate is phosphate. In the coagulation stage, aluminum salt coagulant can form insoluble salts with phosphate, which can be effectively removed by subsequent precipitation.

[0006] Preferably, the dosage ratio of ozone to superphosphate is 1:1 to 1:3.

[0007] Preferably, the superphosphate is at least one of disodium hydrogen monophosphate (Na2HPO5) and sodium diphosphate (Na6P2O8).

[0008] Preferably, the pH value of the reaction system is 6.5 to 8.5.

[0009] Preferably, the drinking water source contains odorous substances.

[0010] Preferably, the odorous substance includes at least one of geosmin and 2-methylisoborneol.

[0011] Preferably, ozone is added through a gas-liquid contact device; and superphosphate is continuously added through a metering pump.

[0012] Further preferably, the gas-liquid contact device includes an aeration titanium plate or a bubble diffuser.

[0013] The invention discloses an application of the ozone / superphosphate-based oxidation pretreatment method in removing odorous substances from drinking water sources.

[0014] Preferably, the drinking water source includes surface water, groundwater, reservoir water, and lake water.

[0015] Preferably, the initial concentration of the odorous substances in the drinking water source is ≤100 ng / L. After degradation using this technology, the odorous substances are stabilized at <10 ng / L, and there is no significant impact on water quality parameters (TOC, color, pH).

[0016] Reaction principle: Ozone (O3) reacts with superphosphate in water:

[0017] O3+PO5 3- → - O3PO5 3- → O3 - + PO5 3-

[0018] PO5 2- +O3→·PO4 2- +2O2

[0019] 2O3+P2O8 4- →2·O3PO4 2- → PO4 2- +3O2

[0020] The generated phosphate radicals (·PO4 2 -) Degradation of odorous substances through electron transfer or hydrogen abstraction principle.

[0021] The present invention proposes an ozone / superphosphate advanced oxidation system, which uses ozone to activate superphosphate to generate phosphate radicals (·PO4 2 -), and works together with ozone in the absence of catalysts to achieve efficient degradation of odorous substances, and the final product is safe and controllable.

[0022] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages:

[0023] 1. Efficient degradation: When the concentration of odorous substances in water sources is ≤100ng / L, the odorous substances can be stably lower than their odor threshold (<10ng / L) after ozone / superphosphate treatment.

[0024] 2. Environmentally friendly: The final product of ozone is oxygen, and the final product of superphosphate is phosphate, which can form an insoluble precipitate with aluminum salt coagulant and can be effectively precipitated and removed through subsequent precipitation process without secondary pollution.

[0025] 3. Economical: Compared with UV-based advanced oxidation technologies, ozone / superphosphate technology significantly reduces energy input and can be used under neutral conditions without the need for additional pH adjustment. This technology can be formed by simply adding superphosphate to the existing ozone pre-oxidation process in the water plant, without the need for process modification, greatly saving the investment cost of the water plant.

[0026] 4. Universality: It is applicable to different water sources (surface water, groundwater, reservoir water, lake water), and has a good removal effect on odorous substances, especially one or both of 2-MIB and GSM. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This invention proves that PO4 2 - The resulting electron paramagnetic resonance spectrum;

[0028] Figure 2 This is a result diagram of Example 5 of the present invention; Figure 2 a is the graph showing the removal effect of 2-MIB changing with pH value; Figure 2 b is the graph showing the removal effect of GSM changing with pH value. DETAILED DESCRIPTION

[0029] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0030] Example 1:

[0031] An ozone / superphosphate-based oxidation pretreatment method and its application, the specific steps of implementation are:

[0032] (1) Water from a reservoir was taken and the initial concentrations of 2-MIB and GSM in the raw water were measured to be 46.1 ng / L and 28.5 ng / L, respectively. The pH was 7.2, the TOC was 4.3 mg / L, and the chromaticity was 13 degrees.

[0033] (2) Ozone was introduced into the raw water sample through a titanium plate aeration at a dosage of 2.0 mg / L; simultaneously, disodium hydrogen superphosphate was added to the raw water sample at a dosage of 6.0 mg / L;

[0034] (3) Set up a comparative experiment:

[0035] Comparative Example 1 (ozonation): ozone was introduced into the raw water sample through a titanium plate aeration, with a dosage of 2.0 mg / L;

[0036] Comparative Example 2 (ozone / hydrogen peroxide system): ozone was introduced into the raw water sample through a titanium plate aeration at a dosage of 2.0 mg / L, and hydrogen peroxide was simultaneously added to the raw water sample at a dosage of 1.0 mg / L;

[0037] Comparative Example 3 (UV / sodium persulfate system): Sodium persulfate was added to the raw water sample and UV lamp was turned on simultaneously. The UV dose was about 1600 mJ / cm 3 ;

[0038] (4) After 10.0 minutes of reaction, samples were taken to determine the residual 2-MIB and GSM in the raw water after treatment with different systems;

[0039] (5) After the reaction, the raw water sample was subjected to a six-phase mixer to simulate the coagulation and sedimentation process of water treatment. 20 mg / L of polyaluminium chloride was added, the coagulation stirring speed was 100 rpm, the coagulation time was 10 minutes, and the static sedimentation time was 15 minutes. The residual phosphate concentration was measured.

[0040] Results: After ozone / superphosphate treatment, the concentrations of 2-MIB and GSM decreased from 46.1 ng / L and 28.5 ng / L to 3.6 ng / L and 2.2 ng / L, respectively. The pH was 7.1, the TOC was 4.0 mg / L, the chromaticity was 13 degrees, and the phosphate concentration after simulated coagulation and sedimentation was 0.08 mg / L.

[0041] In comparison, in Comparative Example 1, the ozone oxidation treatment reduced the concentrations of 2-MIB and GSM from 46.1 ng / L and 28.5 ng / L to 25.4 ng / L and 13.7 ng / L, respectively, with a pH of 7.1, a TOC of 4.3 mg / L, and a chromaticity of 13 degrees; in Comparative Example 2, the ozone / hydrogen peroxide treatment reduced the concentrations of 2-MIB and GSM from 46.1 ng / L and 28.5 ng / L to 7.1 ng / L and 4.2 ng / L, respectively, with a pH of 7.1, a TOC of 4.1 mg / L, and a chromaticity of 13 degrees; in Comparative Example 3, the ultraviolet / sodium persulfate treatment reduced the concentrations of 2-MIB and GSM from 46.1 ng / L and 28.5 ng / L to 27.3 ng / L and 19.1 ng / L, respectively, with a pH of 6.2, a TOC of 4.1 mg / L, and a chromaticity of 13 degrees.

[0042] Example 2:

[0043] An ozone / superphosphate-based oxidation pretreatment method and its application, the specific steps of implementation are:

[0044] (1) Using water from a lake, the initial concentrations of 2-MIB and GSM in the raw water were determined to be 63.6 ng / L and 28.3 ng / L, respectively. The pH was 7.4, the TOC was 3.9 mg / L, and the chromaticity was 15 degrees.

[0045] (2) ozone was introduced into the raw water sample through a titanium plate aeration at a dosage of 5.0 mg / L; sodium peroxydiphosphate was simultaneously added to the raw water sample at a dosage of 5.0 mg / L;

[0046] (3) After 5.0 minutes of reaction, samples were taken to determine the residual 2-MIB and GSM in the raw water;

[0047] (4) After the reaction, the raw water sample was subjected to a six-phase mixer to simulate the coagulation and sedimentation process of water treatment. 20 mg / L of polyaluminium chloride was added, the coagulation stirring speed was 100 rpm, the coagulation time was 10 minutes, and the static sedimentation time was 15 minutes. The residual phosphate concentration was measured.

[0048] Results: The concentrations of 2-MIB and GSM decreased from 63.6 ng / L and 28.3 ng / L to 2.4 ng / L and 1.1 ng / L, respectively. The pH was 7.3, the TOC was 3.6 mg / L, the chromaticity was 15 degrees, and no phosphate was detected after simulated coagulation and sedimentation.

[0049] Example 3:

[0050] An ozone / superphosphate-based oxidation pretreatment method and its application, the specific steps of implementation are:

[0051] (1) Water from a reservoir was taken and the initial concentrations of 2-MIB and GSM in the raw water were measured to be 35.5 ng / L and 18.4 ng / L, respectively. The pH was 7.6, the TOC was 3.7 mg / L, and the chromaticity was 12 degrees.

[0052] (2) ozone was introduced into the raw water sample through titanium plate aeration at a dosage of 4.0 mg / L; disodium hydrogen superphosphate was simultaneously added into the raw water sample at a dosage of 8.0 mg / L;

[0053] (3) After 8.0 minutes of reaction, samples were taken to determine the residual 2-MIB and GSM in the raw water;

[0054] (4) After the reaction, the raw water sample was subjected to a six-phase mixer to simulate the coagulation and sedimentation process of water treatment. 20 mg / L of polyaluminium chloride was added, the coagulation stirring speed was 100 rpm, the coagulation time was 10 minutes, and the static sedimentation time was 15 minutes. The residual phosphate concentration was measured.

[0055] Results: The concentrations of 2-MIB and GSM decreased from 35.5 ng / L and 18.4 ng / L to 2.7 ng / L and 1.8 ng / L, respectively. The pH was 7.5, the TOC was 3.5 mg / L, the chromaticity was 12 degrees, and the phosphate concentration after simulated coagulation and sedimentation was 0.02 mg / L.

[0056] Example 4:

[0057] An ozone / superphosphate-based oxidation pretreatment method and its application, the specific steps of implementation are:

[0058] (1) Ozone was introduced into the pure water through aeration with a dosage of 2.0 mg / L through a titanium plate; simultaneously, disodium superphosphate was added to the test water sample with a dosage of 4.0 mg / L, and 1 mmol / L of 5,5-dimethyl-1-pyrroline-N-oxide was added as ·PO4 2- The capture agent was added and the free radicals were immediately measured using electron paramagnetic resonance spectroscopy;

[0059] (2) The initial concentrations of 2-MIB and GSM were 30 ng / L and 30 ng / L, respectively, as test water samples using pure water, and the pH was adjusted to 7.0 using sulfuric acid and sodium hydroxide;

[0060] (3) Ozone was introduced into the test water sample through a titanium plate aeration at a dosage of 2.0 mg / L; simultaneously, disodium hydrogen superphosphate was added to the test water sample at a dosage of 4.0 mg / L;

[0061] (4) After 6.0 minutes of reaction, samples were taken to determine the residual 2-MIB and GSM in the test water sample;

[0062] (5) After the reaction, the test water sample was subjected to a six-phase mixer to simulate the coagulation and sedimentation process of water treatment, with 20 mg / L of polyaluminium chloride added, a coagulation stirring speed of 100 rpm, a coagulation time of 10 minutes, and a static sedimentation time of 15 minutes, and the residual phosphate concentration was measured.

[0063] Results: As Figure 1 The electron paramagnetic resonance spectrometer detected the characteristic peak of phosphate radical, confirming that PO4 2- The production of phosphate was reduced, and the concentrations of 2-MIB and GSM decreased from 30 ng / L and 30 ng / L to 3.9 ng / L and 4.6 ng / L, respectively. The pH was 7.0, and no phosphate was detected after simulated coagulation and sedimentation.

[0064] Example 5:

[0065] An ozone / superphosphate-based oxidation pretreatment method and its application, the specific steps of implementation are:

[0066] (1) The initial concentrations of 2-MIB and GSM were 30 ng / L and 30 ng / L, respectively, in pure water as test water samples. The pH values were adjusted to 6.5, 7.0, 7.5, 8.0, and 8.5 using sulfuric acid and sodium hydroxide, respectively.

[0067] (2) Ozone was introduced into the test water samples with different pH values through titanium plate aeration at a dosage of 3.0 mg / L; sodium peroxydiphosphate was simultaneously added to the test water samples at a dosage of 5.0 mg / L;

[0068] (3) After 8.0 minutes of reaction, samples were taken to determine the residual 2-MIB and GSM in the test water sample;

[0069] (4) After the reaction, the test water sample was subjected to a six-phase mixer to simulate the coagulation and sedimentation process of water treatment, with 20 mg / L of polyaluminium chloride added, a coagulation stirring speed of 100 rpm, a coagulation time of 10 minutes, and a static sedimentation time of 15 minutes, and the residual phosphate concentration was measured.

[0070] Results: The removal effects of 2-MIB and GSM changed with pH value. Figure 2 At different pH values, the concentrations of 2-MIB and GSM after treatment were all less than 10 ng / L, and the removal efficiency of 2-MIB and GSM was the best at pH 7.5. No phosphate was detected after simulated coagulation and sedimentation.

[0071] Example 6:

[0072] An ozone / superphosphate-based oxidation pretreatment method and its application, the specific steps of implementation are:

[0073] (1) The initial concentrations of 2-MIB and GSM were 30 ng / L and 30 ng / L, respectively, as test water samples using pure water, and the pH was adjusted to 7.5 using sulfuric acid and sodium hydroxide;

[0074] (2) Ozone was introduced into the test water sample through a titanium plate aeration at a dosage of 2.0 mg / L; simultaneously, disodium hydrogen superphosphate was added to the test water sample at a dosage of 10.0 mg / L;

[0075] (3) After 10.0 minutes of reaction, samples were taken to determine the residual 2-MIB and GSM in the test water sample;

[0076] (4) After the reaction, the test water sample was subjected to a six-phase mixer to simulate the coagulation and sedimentation process of water treatment, with 20 mg / L of polyaluminium chloride added, a coagulation stirring speed of 100 rpm, a coagulation time of 10 minutes, and a static sedimentation time of 15 minutes, and the residual phosphate concentration was measured.

[0077] Results: The concentrations of 2-MIB and GSM decreased from 30 ng / L and 30 ng / L to 5.9 ng / L and 7.4 ng / L, respectively. The pH was 7.3, and the phosphate concentration after simulated coagulation and sedimentation was 0.09 mg / L.

Claims

1. An ozone / superphosphate-based oxidation pretreatment method, characterized in that: The following steps are involved: Ozone and superphosphate are added to the drinking water source simultaneously, with the ozone dosage being 2.0-5.0 mg / L and the superphosphate dosage being 5.0-10.0 mg / L; the reaction is allowed to proceed for 5-10 minutes; and finally, the end product of the reaction, phosphate, is removed through coagulation and precipitation processes.

2. The ozone / superphosphate oxidation pretreatment method according to claim 1, characterized in that: The dosage ratio of ozone to superphosphate is 1:1 to 1:

3.

3. The ozone / superphosphate-based oxidation pretreatment method according to claim 1, characterized in that: The superphosphate is at least one of disodium hydrogen monophosphate (Na2HPO5) and sodium diphosphate (Na6P2O8).

4. The ozone / superphosphate-based oxidation pretreatment method according to claim 1, characterized in that: The pH value of the reaction system is 6.5-8.

5.

5. The ozone / superphosphate-based oxidation pretreatment method according to claim 1, characterized in that: The drinking water source contains odorous substances.

6. The ozone / superphosphate-based oxidation pretreatment method according to claim 5, characterized in that: The odorous substance includes at least one of geosmin and 2-methylisoborneol.

7. The ozone / superphosphate-based oxidation pretreatment method according to claim 1, characterized in that: Ozone is added through a gas-liquid contact device; superphosphate is added continuously through a metering pump.

8. Use of the ozone / superphosphate-based oxidation pretreatment method according to claim 1 in removing odorous substances from drinking water sources.

9. The use according to claim 8, characterized in that The drinking water sources include surface water, groundwater, reservoir water, and lake water.

10. The use according to claim 8, characterized in that The initial concentration of the odorous substances in the drinking water source is ≤100 ng / L.

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