An in-situ biological stimulation remediation method for treating Cr(VI) and organic compound combined pollution of groundwater
By activating indigenous microorganisms with sugarcane syrup solution, the problem of efficiently removing hexavalent chromium and nitrobenzene compound pollution from groundwater was solved, achieving efficient, economical and environmentally friendly remediation results.
Patent Information
- Application Number
- CN202610684983.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-05-19
- Publication Date
- 2026-06-23
AI Technical Summary
Existing technologies are insufficient for efficiently removing groundwater contaminated with hexavalent chromium (Cr(VI)) and nitrobenzene (NB). Chemical remediation reagents are easily consumed and pose a risk of secondary pollution. In-situ biostimulation technologies lack systematic comparative studies and clear parameters.
Sugarcane syrup solution was used as the remediation reagent with a concentration of 0.5~2.5 g/L, pH≥7, temperature≥15℃, Cr(VI)≤35 mg/L, and nitrobenzene concentration<75 mg/L. This activated indigenous functional microorganisms to achieve simultaneous reduction and degradation of Cr(VI) and NB.
It achieves efficient removal of Cr(VI) and NB combined pollution, reduces remediation costs, avoids secondary pollution, and provides precise application guidance.
Smart Images
Figure CN122254666A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of groundwater pollution remediation technology, specifically relating to an in-situ bio-stimulation remediation method for treating groundwater with combined Cr(VI) and organic matter pollution. Background Technology
[0002] With the acceleration of industrialization, the types of pollutants emitted by industries such as chromium salt production, electroplating, dyes, pesticides, and fine chemicals are becoming increasingly complex, leading to a growing problem of combined heavy metal and organic pollutant pollution in groundwater environments. Hexavalent chromium (Cr(VI)) is listed as a key controlled pollutant due to its high toxicity, strong mobility, and carcinogenicity; nitrobenzene (NB) is a typical nitro aromatic hydrocarbon with strong toxicity and environmental persistence. When these pollutants coexist, the resulting combined pollution, due to its high toxicity, recalcitrant nature, and potential ecological risks, has become a key focus and challenge in environmental remediation.
[0003] Such complex pollution phenomena have been repeatedly discovered during investigations of actual contaminated sites. For example, Cr(VI) and nitroaromatic hydrocarbons have been detected simultaneously in soil and groundwater samples from some contaminated sites left by chromium salt production enterprises; Cr(VI) and nitrobenzene compounds have also been found as complex pollution in areas affected by wastewater leakage from dye and fine chemical enterprises. These facts indicate that hexavalent chromium (Cr(VI)) and nitrobenzene (NB) compounds can coexist in actual contaminated sites, necessitating the development of remediation technologies for complex pollution systems.
[0004] Currently, the main remediation technologies for this type of pollutant employ chemical remediation reagents. For example, zero-valent iron (ZVI) can act as an electron donor to reduce Cr(VI) to Cr(III), while simultaneously reducing nitrobenzene to intermediate products such as aniline. Fenton-like reactions based on reducing iron systems can generate hydroxyl radicals under certain conditions, achieving simultaneous removal of nitroaromatic hydrocarbons. However, these chemical remediation reagents are prone to non-targeted consumption, leading to reduced reagent utilization efficiency, and also pose a certain risk of secondary pollution, increasing remediation and maintenance costs.
[0005] Compared with chemical remediation, in-situ bioremediation can effectively remove both Cr(VI) and nitrobenzene. Furthermore, due to its advantages such as low cost, high efficiency, minimal ecological disturbance, and strong sustainability, it has gradually become a research hotspot. Among these technologies, in-situ biostimulation involves adding exogenous electron donors to the contaminated system as bioremediation agents to activate indigenous functional microorganisms, thereby reducing or degrading pollutants. Its advantages, including ease of operation, good environmental compatibility, and low remediation cost, have garnered widespread attention in the remediation of complex groundwater pollution.
[0006] Currently, commonly used exogenous electron donors in in-situ biostimulation techniques are mainly divided into two categories: slow-release matrices and fast-acting matrices. Slow-release matrices, represented by emulsified vegetable oils, can continuously release electron donors in aquifers over a long period, maintaining the long-term metabolic needs of microorganisms. Fast-acting matrices, represented by sugarcane syrup, sugars, and organic acids, can rapidly provide microorganisms with usable carbon sources, initiating the remediation process. In existing research, sugarcane syrup, due to its low price and high bioavailability, is often used in bioreduction studies of single hexavalent chromium pollution; while slow-release matrices such as emulsified vegetable oils are more commonly used in studies on the degradation of organic pollutants such as nitrobenzene.
[0007] However, for complex pollution systems where hexavalent chromium and nitrobenzene coexist, there is currently a lack of systematic comparative studies on the removal efficiency of sugarcane syrup and emulsified vegetable oil as carbon sources. Furthermore, the specific remediation parameters for the selected advantageous carbon sources under different environmental factors remain unclear, limiting the precise application of this technology in complex site conditions. Therefore, this invention aims to screen for highly efficient carbon sources suitable for Cr(VI) and NB complex pollution and further explore their optimal application conditions, providing a theoretical basis and technical support for in-situ biostimulated remediation of groundwater with this type of complex pollution. Summary of the Invention
[0008] The purpose of this invention is to provide an in-situ bio-stimulation remediation method for treating groundwater contaminated with Cr(VI) and organic matter. By screening highly efficient remediation reagents and optimizing application conditions, the method can effectively remove the combined pollution.
[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows:
[0010] An in-situ bio-stimulation remediation method for groundwater contaminated with Cr(VI) and organic matter, the remediation method being as follows: using sugarcane syrup solution as a remediation reagent, injecting it into the groundwater contaminated with Cr(VI) and organic matter for remediation; wherein the organic matter is nitrobenzene.
[0011] Furthermore, in the above-mentioned in-situ bio-stimulated remediation method for groundwater contaminated with Cr(VI) and organic matter, the concentration of the sugarcane syrup solution is 0.5~2.5 g / L; the conditions for the groundwater contaminated with Cr(VI) and organic matter are: pH≥7, temperature≥15℃, Cr(VI)≤35 mg / L, and nitrobenzene concentration<75 mg / L.
[0012] Preferably, the concentration of the sugarcane syrup solution is 2.5 g / L.
[0013] Furthermore, in the above-mentioned in-situ bio-stimulation remediation method for groundwater contaminated with Cr(VI) and organic matter, the remediation time is 30-35 days.
[0014] Furthermore, in the above-mentioned in-situ bio-stimulation remediation method for groundwater contaminated with Cr(VI) and organic matter, the sugarcane syrup is a by-product of sugar mills.
[0015] Furthermore, in the above-mentioned in-situ bio-stimulation remediation method for groundwater contaminated with Cr(VI) and organic matter, the Cr(VI) detection method uses the diphenylcarbazide colorimetric method, and the nitrobenzene detection method uses liquid chromatography.
[0016] The beneficial effects of this invention are as follows:
[0017] 1. This invention is the first to propose and verify a method for remediating groundwater contaminated with hexavalent chromium (Cr(VI)) and nitrobenzene (NB) in combination using sugarcane syrup as an electron donor via in-situ biostimulation. There is currently no research on the application of sugarcane syrup in the bioremediation of such combined contamination systems; this invention fills this technological gap.
[0018] 2. This invention, through systematic comparative experiments, screened sugarcane syrup as the optimal carbon source for treating Cr(VI)-NB complex pollution and determined its optimal concentration for efficient remediation. Based on this, the optimal remediation parameters for this method under different pH, temperature, initial Cr(VI) concentration, and initial nitrobenzene concentration conditions were further explored and determined, providing precise technical guidance for practical engineering applications.
[0019] 3. The sugarcane syrup used in this invention, as a bioremediation agent, has significant cost advantages. It is widely available and inexpensive, which can greatly reduce the material costs of remediation projects. Furthermore, sugarcane syrup itself is a natural organic matter that can be completely degraded and utilized by microorganisms without introducing new toxic or harmful substances, thus avoiding the risk of secondary pollution and exhibiting excellent environmental compatibility.
[0020] 4. The method of this invention is simple, easy to implement, and highly targeted. By adding the optimal concentration of sugarcane syrup, the metabolic activity of indigenous functional microorganisms can be rapidly activated, significantly improving the reduction efficiency of Cr(VI) and the degradation rate of NB, thus achieving efficient and simultaneous removal of complex pollutants. This provides an efficient, economical, and environmentally friendly technical means for treating the complex pollution of Cr(VI) and organic matter in groundwater. Attached Figure Description
[0021] Figure 1The figure shows the removal effect of different types of remediation reagents at different concentrations on composite pollutants. Among them, (a) Cr(VI) and (b) nitrobenzene; in the figure, M0.5, M1.5 and M2.5 are 0.5, 1.5 and 2.5 g / L sugarcane syrup, respectively; E0.5, E1.0 and E2.0 are 0.5, 1.0 and 2.0 g / L emulsified vegetable oil, respectively; C is the blank group.
[0022] Figure 2 The effects of sugarcane syrup solution on the removal of Cr(VI) and nitrobenzene complex contaminants under different conditions were investigated, including (a) pH, (b) temperature, (c) Cr(VI) concentration, and (d) nitrobenzene concentration. Detailed Implementation
[0023] The technical solution of the present invention will now be described in further detail with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.
[0024] Example 1: Screening of reagents for in-situ biostimulation remediation of groundwater contaminated with Cr(VI) and nitrobenzene.
[0025] 0.5, 1.5, and 2.5 g / L sugarcane syrup solutions, and 0.5, 1.0, and 2.0 g / L emulsified vegetable oil solutions were selected as in situ stimulation repair agents.
[0026] The steps are as follows:
[0027] (1) Preparation of repair reagents: a) Preparation of sugarcane syrup solution: Sugarcane syrup, a by-product of sugar mills, was selected and diluted to prepare sugarcane syrup solutions with concentrations of 0.5, 1.5, and 2.5 g / L. b) Preparation of emulsified vegetable oil solution: Emulsified vegetable oil mother liquor was mixed with 10% soybean oil, 2% Tween-80, and 88% deionized water in a ratio of 10%, sealed, and placed in a horizontal shaker at 250 rpm for 2 days. The resulting emulsified vegetable oil mother liquor did not separate or break down after standing for 24 hours. After centrifugation at 2000 rpm for 2 minutes, its storage stability was verified to be more than 300 days. Emulsified vegetable oil solutions with concentrations of 0.5, 1.0, and 2.0 g / L were prepared using it.
[0028] (2) Screening of remediation reagents and concentrations: The remediation reagents prepared in step (1) were injected into the sand-simulated aquifers contaminated with Cr(VI)-nitrobenzene composites. The remediation reagents were used to provide nutrients for microorganisms to activate the bioremediation potential of the indigenous microbial community for Cr(VI)-nitrobenzene composite pollution.
[0029] The method for preparing a sand-simulated aquifer contaminated with Cr(VI)-nitrobenzene composite pollution is as follows: the volume of groundwater contaminated with Cr(VI)-nitrobenzene composite pollution is 200 mL, and the mass of sand particles is 250 g, meeting the sampling requirements while closely resembling a saturated aquifer; the temperature is 15℃, pH=7.35, the initial concentration of Cr(VI) is 25 mg / L, and the initial concentration of nitrobenzene is 40 mg / L. The simulated bioreactor is sealed and placed in a light-protected, temperature-controlled shaker at an ambient temperature of 15℃ and an oscillation frequency of 100 rpm to simulate groundwater flow. The optimal reagent and concentration are screened based on pollutant removal efficiency.
[0030] (3) Remediation effect detection: The concentrations of Cr(VI) and nitrobenzene in the remediation system were detected by diphenylcarbazide colorimetric method and liquid chromatography, respectively, and the removal rate was calculated.
[0031] Table 1. Removal effect of different remediation reagents on Cr(VI)-nitrobenzene complex pollutants (time: 33 days)
[0032]
[0033] Table 1 and Figure 1 The results show that a sugarcane syrup solution with a concentration of 2.5 g / L has the best removal effect on Cr(VI) and nitrobenzene complex pollution, with a removal rate of 99% for both pollutants.
[0034] Example 2: Optimization Study of In-situ Biostimulation Method for Groundwater Contaminated with Cr(VI) and Nitrobenzene
[0035] A 2.5 g / L cane sugar syrup solution was selected as the remediation agent for the remediation of complex pollution. A single-factor variable method was used to investigate its remediation effect at different pH, temperature, and concentrations.
[0036] Specifically, except for the specific variables being examined, all other conditions were kept constant: temperature = 20℃, pH = 7, Cr(VI) concentration = 25 mg / L, and nitrobenzene concentration = 50 mg / L.
[0037] The pH, temperature, and concentration conditions mentioned include:
[0038] (1) pH value: 5 (pH5), 7 (pH7), 9 (pH9);
[0039] (2) Groundwater temperature: 15℃ (T15), 20℃ (T20), 25℃ (T25);
[0040] (3) Cr(VI) concentration: 15 mg / L (CR15), 25 mg / L (CR25), 35 mg / L (CR35);
[0041] (4) Nitrobenzene concentration: 25 mg / L (NB25), 50 mg / L (NB50), 75 mg / L (NB75).
[0042] Table 2. Removal effect of 2.5 g / L cane sugar syrup on Cr(VI)-nitrobenzene complex pollutants under different remediation conditions
[0043]
[0044] Table 2 and Figure 2 The results show that within the ranges of pH ≥ 7, temperature ≥ 15℃, Cr(VI) ≤ 35 mg / L, and nitrobenzene concentration < 75 mg / L, the removal rate of Cr(VI) can reach 99%, and the removal rate of nitrobenzene can reach at least 95%.
[0045] In summary, a 2.5 g / L cane sugar syrup solution exhibits the best removal efficiency for Cr(VI) and nitrobenzene combined pollution, achieving a removal rate of 99% for both pollutants. Within the ranges of pH ≥ 7, temperature ≥ 15℃, Cr(VI) ≤ 35 mg / L, and nitrobenzene concentration < 75 mg / L, when this reagent is used to remediate Cr(VI) and nitrobenzene combined pollution, the removal rate of Cr(VI) can reach 99%, and the removal rate of nitrobenzene can reach at least 95%. This method is simple to operate, highly efficient, and provides an effective technical means for treating combined heavy metal and organic pollution in groundwater.
[0046] While the specific embodiments of the present invention have been described above, they are not intended to limit the scope of protection of the invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.
Claims
1. An in-situ biostimulation remediation method for groundwater contaminated with a combination of Cr(VI) and organic matter, characterized in that, The remediation method is as follows: sugarcane syrup solution is used as the remediation reagent and injected into groundwater contaminated with Cr(VI) and organic matter for remediation; the organic matter is nitrobenzene.
2. The in-situ biostimulation remediation method for groundwater contaminated with Cr(VI) and organic matter according to claim 1, characterized in that, The concentration of the sugarcane syrup solution is 0.5~2.5 g / L; the conditions for the combined pollution of groundwater by Cr(VI) and organic matter are: pH≥7, temperature≥15℃, Cr(VI)≤35 mg / L, and nitrobenzene concentration<75 mg / L.
3. The in-situ biostimulation remediation method for groundwater contaminated with Cr(VI) and organic matter according to claim 2, characterized in that, The concentration of the sugarcane syrup solution is 2.5 g / L.
4. The in-situ biostimulation remediation method for groundwater contaminated with a combination of Cr(VI) and organic matter according to claim 2 or 3, characterized in that, The repair time is 30-35 days.
5. The in-situ biostimulation remediation method for groundwater contaminated with Cr(VI) and organic matter according to claim 1, characterized in that, The sugarcane syrup is a byproduct of sugar factories.
6. The in-situ biostimulation remediation method for groundwater contaminated with Cr(VI) and organic matter according to claim 1, characterized in that, The detection method for Cr(VI) is the diphenylcarbazide colorimetric method, and the detection method for nitrobenzene is the liquid chromatography method.