CN-122010314-A - Method for removing complex chromium in wastewater and inhibiting heavy metal toxicity through iron-based secondary mineral mediated biological Fenton reaction and application thereof

CN122010314ACN 122010314 ACN122010314 ACN 122010314ACN-122010314-A

Abstract

The invention discloses a method for removing complex chromium in wastewater by oxidation and inhibiting heavy metal toxicity by an iron-based secondary mineral mediated biological Fenton reaction and application thereof. The method induces Fenton reaction through atmosphere regulation and control of biological/mineral action, and realizes oxidative degradation of complex chromium and inhibition of heavy metal toxicity. The method comprises the steps of reducing iron by facultative iron-reducing bacteria and iron-based secondary minerals under anaerobic conditions, then aerating, initiating Fenton reaction by accumulated ferrous iron and oxygen to oxidize an organic complexing agent to achieve vein breaking, converting to an anaerobic state, reducing Cr (VI) generated by excessive oxidation, and circularly executing aerobic/anaerobic operation until wastewater reaches the standard. The method realizes the advanced treatment of the complex chromium wastewater through a single reactor and has the advantages of simple process, readily available materials and low running cost.

Inventors

XIANG HUAHAO
HU SHUANG
QI YOUXIANG
WANG ZHIQIANG
LEI JIANMING
QI CHUANLEI
ZHOU HUI
LUO ZIHAN
LU HAO
TAN KAIWEN

Assignees

芷兰生态环境建设有限公司

Dates

Publication Date: 20260512
Application Date: 20260413

Claims (11)

1. A method for removing complex chromium in wastewater and inhibiting heavy metal toxicity by using an iron-based secondary mineral mediated biological Fenton reaction is characterized in that the oxygen concentration is regulated and controlled to induce microbial catabolism of iron and the reaction of the iron-based mineral, so as to realize microbial-driven Fenton reaction circulation, so as to perform oxidative degradation on organic complex trivalent chromium in the wastewater and inhibit hexavalent chromium toxicity, and comprises the following steps: S1, activating and expanding culture of facultative iron reducing bacteria in a Luria-Bertani culture medium to obtain high-concentration bacterial suspension, adding the high-concentration bacterial suspension and an iron-based secondary mineral into waste water containing organic complex trivalent chromium, culturing for 6-12 hours under a static or micro-stirring condition under a strict anaerobic condition, and reducing and metabolizing iron by the iron reducing bacteria, wherein iron in the secondary mineral is taken as a terminal electron acceptor to realize reduction and dissolution of iron in the mineral, and releasing high-concentration divalent iron ions to a water phase; s2, immediately performing mechanical stirring aeration or ventilation treatment on the wastewater after the step S1 is completed, maintaining an aerobic state for 0.5 to 2 hours, initiating homogeneous or heterogeneous Fenton reaction by utilizing ferrous iron and oxygen accumulated in an anaerobic stage to generate strong oxidative active oxygen species, oxidizing an organic complexing agent coordinated with trivalent chromium to realize the breaking and degradation, and forming chromium hydroxide precipitation of free trivalent chromium under a weak alkaline or neutral condition, wherein part of trivalent chromium is possibly oxidized into hexavalent chromium under a strong oxidizing environment; S3, stopping aeration and sealing the reactor after the step S2 is completed, converting into a strict anaerobic state, repeating the cultivation conditions of the step S1, reducing hexavalent chromium generated in the step S2 into trivalent chromium, stabilizing the trivalent chromium in a chromium hydroxide precipitation form, and eliminating the ecological toxicity of the trivalent chromium; S4, circularly executing the steps S2 and S3 for a plurality of periods according to the initial pollution load and the treatment effect of the wastewater until the concentration of the total chromium and hexavalent chromium is reduced below the emission standard, thereby realizing complex chromium mineralization and heavy metal toxicity inhibition.
2. The method of claim 1, wherein the facultative iron reducing bacteria of step S1 are one or more of the genera shiva, geobacillus, or enterobacter aerogenes.
3. The method of claim 1, wherein the iron-based secondary mineral in step S1 is one or more of schoenite, jarosite, ferrihydrite, goethite, wurtzite, or hematite, and has a specific surface area of not less than 30m2/g, and is added in an amount of 0.2g/L to 20g/L of wastewater.
4. The method according to claim 1, wherein the initial pH of the wastewater in step S1 is adjusted to 6.0 to 9.0, and the strictly anaerobic condition is achieved by introducing nitrogen or argon, and the dissolved oxygen concentration is controlled to be lower than 0.1mg/L.
5. The method according to claim 1, wherein the completion of the anaerobic incubation in step S1 is determined by monitoring the concentration of ferrous ions in the aqueous phase, and is considered to be complete when the ferrous ion concentration reaches 400mg/L to 600 mg/L.
6. The method according to claim 1, wherein the mechanical agitation aeration or aeration treatment in step S2 is performed by shearing oxygenation with a microporous aeration disc, a jet aerator or a mechanical agitation blade, and the dissolved oxygen concentration is raised to 3mg/L to 5mg/L and maintained stable.
7. The method of claim 1, wherein the completion of the aerobic stage in step S2 is determined by monitoring the concentration of ferrous ions in the aqueous phase, and is considered complete when the ferrous ion concentration is below 20 mg/L.
8. The method of claim 1, wherein the highly oxidizing reactive oxygen species in step S2 comprises one or more of hydroxyl radicals, superoxide radicals, singlet oxygen, and hydrogen peroxide.
9. The method according to claim 1, wherein the hexavalent chromium is reduced to trivalent chromium in the step S3 by using facultative iron-reducing bacteria, which uses ferrous iron or an organic carbon source as an electron donor, through enzyme catalysis or indirect electron transfer, and the anaerobic reduction detoxification is ended at a hexavalent chromium concentration of less than 0.1mg/L.
10. The method of claim 1, wherein the number of circulation cycles and the operating time in step S4 are dynamically optimized based on the initial organic carbon concentration, the total chromium concentration, and the hexavalent chromium residual amount of the wastewater.
11. Use of the method according to any one of claims 1 to 10 for the treatment of waste water containing trivalent chromium in organic complex state, wherein the organic complexing agent is one or more of ethylenediamine tetraacetic acid, citric acid, oxalic acid, tartaric acid or aminotriacetic acid, the waste water type comprising one or more of electroplating and electronics industry waste water, tanning waste water, mining and metallurgy waste water or printing industry waste water.

Description

Method for removing complex chromium in wastewater and inhibiting heavy metal toxicity through iron-based secondary mineral mediated biological Fenton reaction and application thereof Technical Field The invention relates to the technical field of complex heavy metal wastewater treatment, in particular to a method for removing complex chromium in wastewater by using an iron-based secondary mineral mediated biological Fenton reaction and inhibiting heavy metal toxicity and application thereof. Background The heavy metal chromium is widely applied to industries such as leather making, electroplating and the like, and the biotoxicity of the heavy metal chromium is closely related to chemical forms and valence states. Hexavalent chromium is strictly limited to be discharged due to strong carcinogenicity, while trivalent chromium has lower toxicity, but the high fluidity of the trivalent chromium is easily oxidized into hexavalent chromium again, and secondary risk exists. Chromium in industrial chromium-containing wastewater often exists in an organic complex state, such as forms a high-stability complex with oxalic acid, citric acid, ethylenediamine tetraacetic acid and the like, and is difficult to effectively remove by the traditional acid-base precipitation process, so that the total chromium concentration in tail water often exceeds 10mg/L and the emission limit is far more than 1.5 mg/L. The prior treatment technology has the following problems that although advanced oxidation can break collaterals, the advanced oxidation is easy to excessively oxidize to generate hexavalent chromium, an additional reduction working section is needed, the adsorption method has poor selectivity and the adsorbent is difficult to separate, the electro-Fenton method has high cost and multiple side reactions, and the electro-Fenton method is still in a laboratory research stage. Therefore, a process capable of simultaneously realizing advanced oxidation of complex chromium and inhibition of hexavalent chromium formation is needed. Here, a method for removing complex chromium from wastewater and inhibiting heavy metal toxicity by using an iron-based secondary mineral mediated biological Fenton reaction was developed. According to the invention, the high-efficiency anaerobic iron metabolism process of facultative iron reduction bacteria is utilized to realize iron reduction in secondary minerals, the Fenton process generated by high-concentration reduced ferrous iron and oxygen is utilized to realize organic ligand oxidative degradation of organic complex chromium in wastewater through changing the environmental atmosphere, and the anaerobic iron reduction and biological organic metabolism are further realized to jointly inhibit hexavalent chromium toxicity accumulation caused by excessive oxidation, so that the synchronous realization of complex chromium oxidation removal and heavy metal toxicity inhibition in industrial wastewater can be realized through reciprocating circulation. The method has the advantages of taking into account the double functions of deep oxidation of the complex chromium and heavy metal toxicity inhibition, along with simple process equipment requirements, single operation flow and easy realization of large-scale treatment of the chromium-containing wastewater, and provides a high-efficiency and economic solution for industrial complex chromium wastewater treatment. Disclosure of Invention Aiming at the defects of the conventional treatment process, the invention provides a method for removing complex chromium in wastewater by oxidation and inhibiting heavy metal toxicity by using an iron-based secondary mineral mediated biological Fenton reaction, which utilizes anaerobic iron metabolism of facultative iron reduction bacteria to induce iron reduction of the secondary mineral so as to generate high-concentration ferrous iron, realizes the biological Fenton process driven by microorganisms in an oxygen atmosphere to realize the oxidation removal of the organic complex chromium, realizes the secondary reduction of iron and the toxicity reduction of Cr (VI) formed by excessive oxidation in the next anaerobic atmosphere, and can realize the deep treatment of the wastewater containing complex chromium in a simple circulation process. In order to solve the technical problems, the invention adopts the following technical scheme that the deep oxidation removal of organic complex chromium in industrial wastewater and the toxicity inhibition of associated heavy metal Cr (VI) are simultaneously realized: According to a first aspect of the present invention, there is provided a method for oxidation removal of complex chromium and inhibition of heavy metal toxicity in wastewater by an iron-based secondary mineral mediated biological Fenton reaction, which induces microbial catabolism to react with the iron-based mineral by regulating and controlling oxygen concentration, thereby realizing a microbial-driven Fenton r