A method, system and application for remediation of black and odorous sediment.
By using ferrous ferrite to activate persulfate in black and odorous sediment to generate sulfate free radicals, rapid and efficient oxidation and removal of heavy metals are achieved, solving the problems of long cycle and high cost in existing technologies, and realizing efficient heavy metal leaching and harmless treatment of sediment.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SOUTH CHINA AGRICULTURAL UNIVERSITY
- Filing Date
- 2026-02-04
- Publication Date
- 2026-05-26
AI Technical Summary
Existing methods for treating black and odorous sediment have problems such as long treatment cycles and high costs, and the leaching rate of heavy metals in dredged sediment is low, posing a risk of secondary pollution.
The persulfate reacts with ferrous iron in the black and odorous sludge, and the ferrous iron activates the persulfate to generate sulfate free radicals. By stirring, the persulfate is mixed with the black and odorous sludge, oxidizing heavy metals and performing solid-liquid separation, thus achieving rapid and efficient heavy metal removal.
The Fe2+ removal rate is ≥79% within 5 minutes and the AVS removal rate is ≥89% within 2 minutes. At the same time, the leaching rates of Zn, Mn, Ni and Pb are 41%, 32%, 19% and 17% respectively, which reduces the treatment cost and the risk of secondary pollution.
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Figure CN122079433A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of environmental engineering technology, specifically to a method, system, and application for the remediation of black and odorous sediment. Background Technology
[0002] The reducing oxygen-consuming substances in black and odorous river sediments mainly include sulfides (AVS), low-valence heavy metals (mainly ferrous), ammonia nitrogen, and easily degradable organic matter. Heavy metals that enter the water body accumulate in the riverbed sediment through adsorption, complexation, and precipitation. Therefore, the concentration of heavy metals in the sediment is much higher than that in the overlying water, making river sediments a pollution carrier for heavy metals.
[0003] Dredging technology has become a major method for treating black and odorous sediment due to its advantage of directly and quickly eliminating endogenous pollution. However, the large amount of black and odorous sediment generated by dredging faces the dual challenges of secondary pollution and limited resource utilization. Dredged sediment is rich in sulfides, ferrous oxide, and other blackening and odor-causing substances, and is also accompanied by heavy metal pollution such as Zn, Cu, Ni, and Pb. Direct dumping or improper handling can lead to the migration and diffusion of heavy metals, threatening the surrounding soil and water environment. Based on the diverse composition of river and lake dredged sediment, existing treatment processes, including dredged sediment conditioning, dewatering, solidification, stabilization, and ex-situ remediation, provide important guarantees for the safe disposal of river and lake dredged sediment. Currently, dredged sediment conditioning technologies are mainly divided into biological conditioning, physical conditioning, and chemical conditioning. Biological conditioning includes bioleaching and microbial flocculation, which generally have a long conditioning cycle; physical conditioning includes thermal conditioning, ultrasonic conditioning, and inorganic flocculation / coagulation technology, which are more expensive.
[0004] In summary, existing methods for treating black and odorous sediment suffer from problems such as long treatment cycles and high costs. Summary of the Invention
[0005] To address the technical problems existing in the prior art, the purpose of this invention is to provide a method, system, and application for the remediation of black and odorous sediment, capable of remediating Fe within 5 minutes. 2+ The removal rate is ≥79% and the AVS removal rate is ≥89% within 2 minutes. At the same time, the leaching rates of Zn, Mn, Ni and Pb in black and odorous sediment can reach 41%, 32%, 19% and 17% respectively, and the required cost is relatively low.
[0006] To achieve the above objectives, the present invention adopts the following technical solution:
[0007] A method for remediating black and odorous sediment includes the following steps: obtaining black and odorous sediment and homogenizing it; detecting the ferrous content of the sediment and calculating the dosage of persulfate based on the molar ratio; using the ferrous-rich sediment as an activator, adding persulfate, and stirring the persulfate and sediment to allow them to mix and react; adjusting the stirring time of the sediment and persulfate; utilizing the ferrous in the sediment to activate the persulfate and generate sulfate free radicals, which oxidize the black and odorous substances, thereby leaching out heavy metals from the sediment; after the reaction, centrifuging and filtering the mixture of sediment and persulfate, collecting the interstitial water containing heavy metals, and washing the centrifuged mixture to obtain harmless sediment.
[0008] Preferably, the method for homogenizing the sediment is as follows: the black and odorous sediment is passed through a sieve to homogenize it; the homogenized black and odorous sediment is placed in a reaction vessel, deionized water is added, and the vessel is sealed and left to stand to create an anaerobic environment inside.
[0009] Preferably, the screen is made of 60-mesh stainless steel.
[0010] Preferably, the method for detecting the ferrous content of black and odorous sediment is: measurement by hydrochloric acid extraction of o-phenanthroline spectrophotometry.
[0011] Preferably, the molar ratio of persulfate to ferrous sulfate is 2.
[0012] Preferably, the method for centrifuging and filtering the mixture of black and odorous bottom sludge and persulfate after reaction is as follows: the mixture of black and odorous bottom sludge and persulfate is placed in a centrifuge, the centrifuge is set to a working state of 3000 rpm and a working time of 10 min, and the filter cloth pore size of the centrifuge is 20 micrometers.
[0013] Preferably, the method for washing the mixture of black and odorous bottom sludge and persulfate after reaction is as follows: put the mixture of black and odorous bottom sludge and persulfate into a centrifuge, add pure water to the centrifuge to obtain the mixture to be washed, start the centrifuge to centrifuge and wash to obtain harmless bottom sludge.
[0014] Preferably, the heavy metals include Zn, Mn, Ni and Pb.
[0015] A remediation system for black and odorous sediment, the remediation system is applied to the remediation method, the remediation system includes a homogenization treatment module, a persulfate addition module, a mixing reaction module, a stirring module, a ferrous content detection module and a solid-liquid separation module;
[0016] The homogenization module is used to homogenize the collected black and odorous sediment.
[0017] The ferrous content detection module is used to detect the ferrous content of black and odorous sediment after homogenization treatment.
[0018] The persulfate dosing module is set on the mixing reaction module. The persulfate dosing module is used to add persulfate to the mixing reaction module according to the ferrous content of the black and odorous sediment.
[0019] The mixing and reaction module is used to receive homogenized black and odorous sediment and persulfate;
[0020] The stirring module is installed in the mixing and reaction module. The stirring module is used to stir the black and odorous bottom mud and persulfate in the mixing and reaction module to make them react.
[0021] The solid-liquid separation module is used to separate the black and odorous sludge and persulfate mixture after the reaction, and also to separate the black and odorous sludge and pure water after the reaction.
[0022] An application of a remediation method, which is used for the harmless treatment of dredged black and odorous bottom sediment.
[0023] In summary, the present invention has the following advantages:
[0024] The repair method of the present invention can repair Fe within 5 minutes 2+ The removal rate is ≥79% and the AVS removal rate within 2 minutes is ≥89%. At the same time, the leaching rates of Zn, Mn, Ni and Pb in the black and odorous sediment can reach 41%, 32%, 19% and 17% respectively. Compared with the existing technology that requires the addition of transition metal catalysts or physical conditioning to repair black and odorous sediment, the repair method of this invention only needs to add persulfate, which, together with the ferrous metal in the black and odorous sediment, can oxidize the black and odorous substances, so that the heavy metals in the black and odorous sediment can be leached out, and the required cost is low. Attached Figure Description
[0025] Figure 1 This is a flowchart of the repair method steps.
[0026] Figure 2 The graph shows the change in ferrous content with reaction time when the molar ratio of persulfate to ferrous iron is 2.
[0027] Figure 3 The graph shows the change in sulfide content with reaction time when the molar ratio of persulfate to ferrous sulfate is 2.
[0028] Figure 4 A bar chart showing the heavy metal content of black and odorous sediment treated with different molar ratios of persulfate and ferrous sulfate.
[0029] Figure 5 ESR spectrum after adding persulfate to black and odorous sediment. Detailed Implementation
[0030] The present invention will now be described in further detail with reference to specific embodiments.
[0031] Example 1
[0032] like Figures 1-5 As shown in this embodiment, a method for remediating black and odorous sediment includes the following steps: obtaining black and odorous sediment and homogenizing it; detecting the ferrous content of the sediment and calculating the amount of persulfate to be added based on the molar ratio; using ferrous-rich black and odorous sediment as an activator, adding persulfate, and stirring the persulfate and sediment to mix and react; adjusting the stirring time of the sediment and persulfate; using the ferrous in the sediment to activate the persulfate and generate sulfate free radicals, which oxidize the black and odorous substances, thereby leaching out the heavy metals in the sediment; after the reaction, centrifuging and filtering the mixture of the sediment and persulfate, collecting the interstitial water containing heavy metals, and washing the mixture after centrifugation to obtain harmless sediment.
[0033] The method for homogenizing the sediment is as follows: The black and odorous sediment is sieved to homogenize it; the homogenized sediment is then placed in a reaction vessel, deionized water is added, and the vessel is sealed and allowed to stand, creating an anaerobic environment. This treatment eliminates the need for subsequent adjustments to the reaction environment, demonstrating that the oxidation of reducing substances, leaching of heavy metals, and alteration of the reducing environment are entirely caused by the addition of persulfate, requiring no further treatment.
[0034] The screen used is a 60-mesh stainless steel screen. By using a 60-mesh stainless steel screen to treat the black and odorous sediment, it is ensured that there are no large impurities such as stones and plastics in the sediment during the reaction.
[0035] The method for detecting the ferrous content in black and odorous sediment is as follows: it is measured using the hydrochloric acid extraction method for o-phenanthroline. This method accurately detects the ferrous content in black and odorous sediment, allowing for the calculation of the persulfate dosage based on the determined molar ratio of persulfate to ferrous iron.
[0036] The molar ratio of persulfate to ferrous iron is 2. By setting the molar ratio of persulfate to ferrous iron to 2, the Fe in the black and odorous sediment is reduced. 2+The removal rate reaches 75%, the AVS removal rate reaches 85%, and the maximum leaching rates of heavy metals Zn, Mn, Ni, and Pb can reach 41%, 32%, 19%, and 17%, respectively. It simultaneously achieves complete oxidation of blackening and odor-causing substances and efficient leaching of heavy metals. If the molar ratio of persulfate to ferrous iron is less than 2 or greater than 2, the removal rates of Fe²⁺, AVS, and heavy metals in the black and odorous sediment will all be reduced accordingly.
[0037] The method for centrifuging and filtering the mixture of black and odorous bottom sludge and persulfate after reaction is as follows: the mixture of black and odorous bottom sludge and persulfate is placed in a centrifuge, the centrifuge is set to 3000 rpm for 10 min, and the filter cloth pore size of the centrifuge is 20 micrometers.
[0038] The method for washing the mixture of black and odorous bottom sludge and persulfate after reaction is as follows: put the mixture of black and odorous bottom sludge and persulfate into a centrifuge, add pure water to the centrifuge to obtain the mixture to be washed, start the centrifuge to centrifuge and wash to obtain harmless bottom sludge.
[0039] The heavy metals leached from the black and foul-smelling sediment include Zn, Mn, Ni, and Pb.
[0040] principle:
[0041] (1) Persulfate oxidation of sulfides (AVS) and ferrous iron mainly occurs through Fe 2+ Activating PDS generates sulfate radicals, which have a high redox potential of +2.5 to +3.1 V (relative to the standard hydrogen electrode, SHE), and can rapidly and directly oxidize Fe. 2+ Reducing substances such as AVS. Homogenization and stirring of the sediment can ensure sufficient contact between the sediment and persulfate to trigger advanced oxidation reactions. Thorough stirring can improve activation efficiency and accelerate the oxidation rate of reducing substances.
[0042] (2) The hydrogen ions generated during the reaction will undergo redox reactions with most metals or their compounds, causing metal atoms and compounds to be converted into ions and dissolved. At the same time, the strong oxidizing property of sulfate free radicals will also destroy organic and sulfide-bound heavy metals, causing them to be released and promoting the leaching of heavy metals. Stirring and mixing can make the pH and sulfate free radical concentration in all regions of the system reach a uniform level, thus promoting the leaching efficiency of heavy metals.
[0043] (3) Due to the oxidation of reducing substances and the leaching of heavy metals in the sediment, the interstitial water contains a large amount of polluting regeneration substances (heavy metal ions, sulfate ions, etc.). If solid-liquid separation is not carried out, there is a risk of blackening and odor return and heavy metal biological refixation. Therefore, mud-water separation is required. Then, the oxidized sediment is washed again to remove the pollutants remaining in the interstitial water. At this time, the sediment with no pollution risk and harmlessness is obtained, which can be used for green resource utilization.
[0044] Example 2
[0045] This embodiment provides a remediation system for black and odorous sediment. The remediation system is applied to the remediation method and includes a homogenization treatment module, a persulfate addition module, a mixing reaction module, a stirring module, a ferrous content detection module, and a solid-liquid separation module.
[0046] The homogenization module is used to homogenize the collected black and odorous sediment.
[0047] The ferrous content detection module is used to detect the ferrous content of black and odorous sediment after homogenization treatment.
[0048] The persulfate dosing module is set on the mixing reaction module. The persulfate dosing module is used to add persulfate to the mixing reaction module according to the ferrous content of the black and odorous sediment.
[0049] The mixing and reaction module is used to receive homogenized black and odorous sediment and persulfate;
[0050] The stirring module is installed in the mixing and reaction module. The stirring module is used to stir the black and odorous bottom mud and persulfate in the mixing and reaction module to make them react.
[0051] The solid-liquid separation module is used to separate the black and odorous sludge and persulfate mixture after the reaction, and also to separate the black and odorous sludge and pure water after the reaction.
[0052] Specifically, the homogenization module can be an existing sediment vibrating screen, which removes large impurities such as stones and plastics from the black and odorous sediment. The persulfate dosing module can be an existing peristaltic pump that pumps the dissolved persulfate to the mixing reaction vessel. The mixing reaction vessel is a hollow reaction vessel; for example, in this embodiment, the mixing reaction vessel is a 6.28L (bottom radius 10cm, height 20cm) cylindrical reaction tank, and the stirring module is a JBH-200 constant speed stirrer (200W). The ferrous content detection module uses the existing spectrophotometric method for extracting o-phenanthroline with hydrochloric acid, and the solid-liquid separation module is an existing centrifuge.
[0053] The parts not mentioned in this embodiment are the same as in Embodiment 1.
[0054] Example 3
[0055] This embodiment provides an application of a remediation method, which is used for the harmless treatment of dredged black and odorous sediment.
[0056] By applying the remediation method of Example 1 to the harmless treatment of dredged black and odorous sediment, no additional catalyst is required, the treatment cycle is extremely short, and Fe is achieved within a very short time (5 minutes). 2+ The removal rate is ≥79%, and the AVS (acid volatile sulfide) removal rate is ≥89% in a very short time (2 minutes). A large amount of heavy metals are leached out, and the treated sediment has reduced toxicity and secondary pollution, enabling resource utilization.
[0057] The parts not mentioned in this embodiment are the same as in Embodiment 1.
[0058] Specific application example 1
[0059] Reaction vessel: 6.28L (bottom radius 10cm, height 20cm) cylindrical reaction tank, stirring module: JBH-200 constant speed stirrer (200w).
[0060] Black and odorous sediment samples: The sediment samples were collected from the top 0-20cm layer of a black and odorous river in the Pearl River Basin. After removing impurities, the sediment was homogenized.
[0061] Reagent 1 - Persulfate: Potassium persulfate (PDS, analytical grade).
[0062] Reagent 2 - Deionized water.
[0063] 2. Specific steps:
[0064] Homogenization of black and odorous sediment: Take 4 kg of homogenized black and odorous sediment and place it in a reaction tank. Add 1 L of deionized water, seal and let stand for 24 h to simulate an anaerobic environment.
[0065] PDS addition: based on the Fe content of the bottom sediment. 2+ Calculate the PDS dosage and set the PDS / Fe content. 2+ With a molar ratio of 2, dissolve PDS in 500 mL of deionized water, spray it evenly into the sediment while stirring, and continue stirring for 10 minutes to ensure uniform mixing.
[0066] Synergistic reaction: The reaction temperature is 25℃, and the reaction time is 6 hours;
[0067] Solid-liquid separation: After the reaction is complete, take a mud-water mixture sample, centrifuge it, and collect the interstitial water;
[0068] Effects of removing black and odorous substances: PDS / Fe 2+ With a molar ratio of 2, after 6 hours of reaction, Fe... 2+The removal rate reaches 75%, and the AVS removal rate reaches 85%. The maximum leaching rates of heavy metals, including Zn, Mn, Ni, and Pb, can reach 41%, 32%, 19%, and 17%, respectively. It simultaneously achieves complete oxidation of black and odorous substances and efficient leaching of heavy metals.
[0069] ESR analysis confirmed that PDS was absorbed by Fe in the sediment. 2+ The activation generates sulfate free radicals, and the decrease in pH promotes the leaching of heavy metals, verifying the effectiveness of the "de-blackening and odor removal-heavy metal leaching" synergistic mechanism of the present invention.
[0070] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.
Claims
1. A method for remediating black and odorous bottom sediment, characterized in that, Includes the following steps: Obtain black and odorous sediment and homogenize it. The ferrous content of black and odorous sediment was tested, and the amount of persulfate added was calculated based on the molar ratio. Using ferrous black and odorous sediment as an activator, persulfate was added, and the persulfate and black and odorous sediment were stirred to mix and react with each other. Adjust the mixing time of the black and foul-smelling sediment and persulfate; The ferrous iron in the black and odorous sediment activates persulfate to generate sulfate free radicals, which then oxidize the black and odorous substances, causing the heavy metals in the black and odorous sediment to leach out. After the reaction is completed, the mixture of black and odorous bottom sludge and persulfate is centrifuged and filtered to collect the interstitial water containing heavy metals. The mixture after centrifugation is then washed to obtain harmless bottom sludge.
2. The method for remediating black and odorous sediment according to claim 1, characterized in that, The method for homogenizing bottom sediment is as follows: the black and odorous bottom sediment is passed through a sieve to homogenize it; the homogenized black and odorous bottom sediment is placed in a reaction vessel, deionized water is added, and the vessel is sealed and allowed to stand to form an anaerobic environment.
3. The method for remediating black and odorous sediment according to claim 2, characterized in that: The screen is made of 60-mesh stainless steel.
4. The method for remediating black and odorous sediment according to claim 1, characterized in that, The method for detecting the ferrous content in black and odorous sediment is as follows: it is measured by spectrophotometry using hydrochloric acid extraction of o-phenanthroline.
5. The method for remediating black and odorous sediment according to claim 1, characterized in that: The molar ratio of persulfate to ferrous sulfate is 2.
6. The method for remediating black and odorous sediment according to claim 1, characterized in that, The method for centrifuging and filtering the mixture of black and odorous bottom sludge and persulfate after reaction is as follows: the mixture of black and odorous bottom sludge and persulfate is placed in a centrifuge, the centrifuge is set to 3000 rpm for 10 min, and the filter cloth pore size of the centrifuge is 20 micrometers.
7. The method for remediating black and odorous sediment according to claim 1, characterized in that, The method for washing the mixture of black and odorous bottom sludge and persulfate after reaction is as follows: put the mixture of black and odorous bottom sludge and persulfate into a centrifuge, add pure water to the centrifuge to obtain the mixture to be washed, start the centrifuge to centrifuge and wash to obtain harmless bottom sludge.
8. The method for remediating black and odorous sediment according to claim 1, characterized in that, Heavy metals include Zn, Mn, Ni, and Pb.
9. A system for remediating black and odorous sediment, characterized in that: The remediation system is applied to the remediation method according to any one of claims 1-8. The remediation system includes a homogenization module, a persulfate addition module, a mixing reaction module, a stirring module, a ferrous content detection module, and a solid-liquid separation module. The homogenization module is used to homogenize the collected black and odorous sediment. The ferrous content detection module is used to detect the ferrous content of black and odorous sediment after homogenization treatment. The persulfate dosing module is set on the mixing reaction module. The persulfate dosing module is used to add persulfate to the mixing reaction module according to the ferrous content of the black and odorous sediment. The mixing and reaction module is used to receive homogenized black and odorous sediment and persulfate; The stirring module is installed in the mixing and reaction module. The stirring module is used to stir the black and odorous bottom mud and persulfate in the mixing and reaction module to make them react. The solid-liquid separation module is used to separate the black and odorous sludge and persulfate mixture after the reaction, and also to separate the black and odorous sludge and pure water after the reaction.
10. The application of the repair method according to any one of claims 1-8, characterized in that: The remediation method is applied to the harmless treatment of dredged black and odorous bottom sediment.