CN103232096B - In-situ repairing system and repairing method capable of continuously removing Cr in underground water - Google Patents
In-situ repairing system and repairing method capable of continuously removing Cr in underground water Download PDFInfo
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- CN103232096B CN103232096B CN201310150256.6A CN201310150256A CN103232096B CN 103232096 B CN103232096 B CN 103232096B CN 201310150256 A CN201310150256 A CN 201310150256A CN 103232096 B CN103232096 B CN 103232096B
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Abstract
The invention relates to an in-situ repairing system and a repairing method capable of continuously removing Cr in underground water; the repairing system comprises one or more layers of iron nets, one or more layers of PVC (Polyvinyl Chloride) nets, an iron filling material and an iron brush type electrode, wherein one or more layers of iron nets are put in a caisson of a permeable reactive barrier (PRB); one or more layers of PVC nets are put in the iron nets; the iron filling material is put in the PVC nets; the iron brush type electrode is inserted into the iron filling material; the iron brush type electrode is put on the sharp part at one end in the caisson of the PRB and contacted with the iron nets; and a power supply is connected with the iron nets and the iron brush type electrode. The repairing method disclosed by the invention comprises the following steps that: after the iron filling material is passivated, one corner of the iron net is selected as the anode; the iron brush type electrode is selected as the cathode; the iron net and the iron brush type electrode are electrified through the power supply; then, the other corner of the iron net is selected as the anode; the iron net is electrified for the same time; finally, the anode and the cathode are reversed and electrified for the same time; a lot of hydrogen is separated on the surface at one side of the cathode; the hydrogen has the functions of stripping and eliminating an adhesive layer on the cathode, so that the passivated layer on the surface of iron is stripped; and a lot of iron ions are dissolved at one side of the anode and used for stripping sediment on the surface of the iron filling material. The in-situ repairing system and the repairing method disclosed by the invention are capable of continuously removing Cr pollution and effectively solving the passivation problem of application of the traditional PRB.
Description
Technical field
The present invention relates to the removal technical field of Cr in underground water, be specifically related to original position repair system and restorative procedure that a kind of sustainable removal underground water Cr pollutes.
Background technology
At present, the underground water in the many areas of China and even the world is all subject in various degree Cr and pollutes, serious threat resident's drinking water safety, and in underground water, Cr pollutes and is more and more subject to extensive concern.Cr is listed in one of eight of harm maximum kinds of chemical substances, is one of internationally recognized three kinds of carcinogenic metals, is also one of 129 kinds of generally acknowledged priority pollutants of U.S. EPA simultaneously.The World Health Organization (WHO) " water quality standard for drinking water " and China's " drinking water sanitary standard " all regulation sexavalence Cr standard are 0.05mg/L.The underground water reparation that polluted by Cr adopts Pump-and-Treat method conventionally, comprises the Composite Set established law of physico-chemical process, chemical method, biological process and these technology.Extraction-facture is processed after underground pollution water is extracted again, cost is high, the cycle is long, energy consumption greatly, easily causes secondary pollution, can not carry out original position reparation and effectively solve and extract the problem directly using out, more can not macroscopic view, ensure China resident's drinking water safety for a long time.PRB(infiltration type reaction wall) technology is a kind of emerging based technique for in-situ remediation of efficient economy, this technology stores treatment measures without additionaling power, ground, operation and maintenance cost is lower, can remove multiple pollutant simultaneously, comprises heavy metal, organism, radionuclide and nutritive substance.This technology has successfully applied on the spot during polluted underground water repairs America and Europe, in this technology of China also in the starting stage.Inexpensive owing to having, the high reduction potential of Zero-valent Iron, speed of response are fast, become PRB application maximum reaction medium material.
A lot of scenes and laboratory applications Fe-PRB remove Cr (VI) and have obtained good effect.Cr in Fe-PRB system (VI) is first reduced to Cr (III), follow Zero-valent Iron to be oxidized to Fe (II) or Fe (III), then Cr precipitates with the form of Cr (III) oxyhydroxide or Fe (III)/Cr (III) oxyhydroxide.In PRB operational process, Zero-valent Iron or ferrous iron are oxidized to ferric iron by Cr (VI), cause that pH value raises.Meanwhile, Zero-valent Iron is oxidized by oxygen under aerobic condition, under anaerobic can be oxidized by water, is all accompanied by the rising of pH value.This makes in PRB During Process of Long-term Operation, forms alkaline condition, causes the precipitation such as oxide compound, oxyhydroxide of Zero-valent Iron Surface Creation iron.At present, the bottleneck problem in PRB application process is the problem that the passivation due to Zero-valent Iron that occurs in During Process of Long-term Operation causes processing power to reduce.Zero-valent Iron surface precipitation can cover iron surface avtive spot in various degree according to thickness is different with composition, causes electronics to transmit resistance increment, and Zero-valent Iron surface reaction activity reduces.Henderson and Demond have collected the original position PRB service data of multiple contaminated sites, identify the parameter that affects PRB operation, think that the activity of Zero-valent Iron is the main factor of the permanently effective operation of restriction PRB than perviousness reduction.Flurry etc. carry out research in 4 years to Switzerland Cr contaminated site PRB, find that the major cause that causes PRB treatment effect to reduce is the passivation of Zero-valent Iron, not blockage phenomenon of while.The mineral ion composition of polluted water can affect the generation of precipitation, in laboratory and on-the-spot operation PRB, find multiple sedimentable matter, as Cr (III)-Fe (III) precipitation of hydroxide of Fe (III) and Cr (III) co-precipitation formation, the oxide compound of various iron, oxyhydroxide and the carbonate deposition etc. of iron.At present the Zero-valent Iron solution passivating method of report comprises pickling and supersound process etc., but these means exist in varying degrees problems such as processing costs is high, workload large, operability is not strong.Therefore, need at present that a kind of cost is low, efficiency is high badly, easy handling, can be used for the technology in actual treatment place, affect thereby effectively solve the problem of passivation that PRB applies.
The field engineering of infiltration type reaction wall has following several field engineering conventionally: conventional groove formula is installed, caisson type is installed, landfill is installed and excavated continuously to mandrel type.Groove installation adopts the mode that hollows out backfill, around the reaction member of intending excavation, squeezes into sheet pile with bracing reinforcement, the method that adopts afterwards the equipment such as backhoe and clampshell dredging shovel to dig out a groove.Caisson type is installed as and utilizes prefabricated steel caisson to help excavation, when caisson reaches the set degree of depth, its inner soil is removed, and fills out reflection medium.Mandrel type is installed and is utilized a hollow steel axle or mandrel to open up a packaged space of filling out reaction medium, then medium is filled into.Continous way excavation can excavate the narrow groove of 40cm-60cm continuously, simultaneously immediately with reaction medium backfill or put into the continuous barrier film of high-density polyvinyl chloride of antiseepage.Pinniform is wider, water proof funnel-wicket gate system of concentration is higher, flow velocity the is larger multiplex caisson in place polluting, and caisson general diameter is 2.4m or less, and diameter is more little more easily to be pushed and keeps vertical state.
Summary of the invention
The problem existing in order to solve above-mentioned prior art, the original position repair system and the restorative procedure that the object of the present invention is to provide a kind of sustainable removal underground water Cr to pollute, this original position repair system can be removed sustainably Cr and pollute, effectively solve the problem of passivation of conventional P RB application, after traditional PRB system filler Zero-valent Iron passivation without conversion materials more, realize the former bit recovery of ironwork, extended the operation life of PRB system.
For reaching above object, the present invention adopts following technical scheme:
The original position repair system that a kind of sustainable removal underground water Cr pollutes, comprise one or more layers iron net 2 of putting into infiltration type reaction wall caisson 1 and being close to its inwall, be placed in one or more layers PVC net 3 in iron net 2, be placed in the iron filler 4 in PVC net 3, insert the iron brush electrode 5 in infiltration type reaction wall caisson 1 central position iron filler 4, the tip that described iron brush electrode 5 is placed in infiltration type reaction wall caisson 1 interior one end touches iron net, also comprises the power supply 6 being connected with iron net 2 and iron brush electrode 5.
Also comprise that the ionogen being communicated with infiltration type reaction wall caisson 1 adds stirred vessel 7.
The virtual voltage of described power supply 6 is 0-50V, and watt current is 0-5A.
The restorative procedure of original position repair system described above, first flows into synthetic Cr polluted water from infiltration type reaction wall caisson 1 water-in, water outlet flows out, and when reaction reaches Preset Time, iron filler 4 is to Cr
6+clearance lower than set clearance time, after being 4 passivation of iron filler, choosing 2 one jiaos, iron net is positive pole, iron brush electrode 5 is negative pole, switch on after 1-30min by power supply 6, choose again iron net 2 another angles for anodal, switch on the same time, finally put upside down again positive and negative electrode, switch on the same time, by additional certain electric field, one side of negative electrode, a large amount of hydrogen can be separated out in surface, and a large amount of bubbles break loose from iron filler 4 surfaces, adhesion layer on it is peeled off and scavenging(action), iron surface passivation layer is peeled off; The a large amount of strippings of one side iron ion of anode, peel off the precipitation on iron filler 4 surfaces;
In electrochemistry solution passivating process, when iron is as negative electrode and while having certain potential value, there is following electrochemical reaction, separate out a large amount of hydrogen:
Anode: 2H
2o → O
2+ 4H
++ 4e
-
Negative electrode: 2H
2o+2e
-→ H
2+ 2OH
-
When iron is during as anode, there is following electrochemical reaction, anode has iron ion and produces:
Anode: Fe → Fe
2++ 2e
-
Negative electrode: 2H
2o+2e-→ H
2+ 2OH
-(2) O
2+ 2H
2o+4e
-→ 4OH
-.
In when energising, (7 to iron filler, (in 4, add anhydrous sodium sulphate as ionogen, the dosage of anhydrous sodium sulphate is 0.5g/L to add stirred vessel by ionogen.
In described synthetic Cr polluted water, Cr is 25mg/L; Na
2sO
4for 0.5g/L.
Compared to the prior art, tool has the following advantages in the present invention:
(1) all processing complete in single reaction unit, without conversion materials more, and escapable cost;
(2) separating passivation post-reactor, to remove Cr efficiency high and can not cause secondary pollution
(3) be applicable to PRB caisson type field engineering, construct simple, easy to operate, level of automation is high.
Brief description of the drawings
Fig. 1 is original position repair system skeleton view of the present invention.
Fig. 2 is original position repair system simulated slot of the present invention (caisson volume device) skeleton view.
Fig. 3 is iron brush electrode schematic diagram, and wherein Fig. 3 a is front view, and Fig. 3 b is vertical view.
Fig. 4 is Cr temporal evolution graphic representation in original position repair system.
Embodiment
Below in conjunction with drawings and the specific embodiments, the present invention is described in further detail.
As depicted in figs. 1 and 2, the original position repair system that a kind of sustainable removal underground water Cr of the present invention pollutes, comprise one or more layers iron net 2 of putting into infiltration type reaction wall caisson 1 and being close to its inwall, be placed in one or more layers PVC net 3 in iron net 2, be placed in the iron filler 4 in PVC net 3, insert the iron brush electrode 5 in infiltration type reaction wall caisson 1 central position iron filler 4, the tip that described iron brush electrode 5 is placed in infiltration type reaction wall caisson 1 interior one end touches PVC net 3, also comprises the power supply 6 being connected with iron net 2 and iron brush electrode 5.Also comprise that the ionogen being communicated with infiltration type reaction wall caisson 1 adds stirred vessel 7.
As the preferred embodiment of the present invention, the virtual voltage of described power supply 6 is 0-50V, and watt current is 0-5A.
As shown in Figure 3, be iron brush electrode schematic diagram, wherein Fig. 3 a is front view, Fig. 3 b is vertical view.
Embodiment
Adopt a 6x4x3=72cm
3organic plastics reactive tank.A direct current stabilizer is as power supply, and its virtual voltage is 0-50V, and watt current is 0-5A.In experiment, adopt synthetic Cr polluted water (Cr, 25mg/L; Na
2sO
4; 0.5g/L, experiment water inlet adopts the mode of upwelling to carry out, and flows into, and flow out from reactor head containing Cr polluted water with 4mL/min flow velocity from reactor bottom.Be 198min left and right when the reaction times, discovery iron filler is compared significantly and is reduced with initial clearance the clearance of Cr (VI).Power up with 10v voltage, choose respectively iron net wherein one jiao for anodal, iron brush electrode is negative pole electrolysis 5min, then to choose another angle be the operation before anodal repetition, then puts upside down positive and negative electrode.As shown in Figure 4, can find out that comeback of removal rate rate is initial clearance 108.2% after electrolysis, the life-span of PRB is effectively extended.
As the optimal way of the present embodiment, in the time of energising, add stirred vessel 7 by ionogen and add anhydrous sodium sulphate as ionogen in iron filler 4, the dosage of anhydrous sodium sulphate is 0.5g/L.By adding anhydrous sodium sulphate, make solution there is certain specific conductivity, if treatment soln specific conductivity is enough large, can not add sodium sulfate, specifically can add with actual treatment water condition.
Claims (6)
1. the original position repair system that sustainable removal underground water Cr pollutes, it is characterized in that: comprise one or more layers iron net (2) of putting into infiltration type reaction wall caisson (1) and being close to its inwall, be placed in one or more layers PVC net (3) in iron net (2), be placed in the iron filler (4) in PVC net (3), insert the iron brush electrode (5) in infiltration type reaction wall caisson (1) central position iron filler (4), the tip that described iron brush electrode (5) is placed in infiltration type reaction interior one end of wall caisson (1) touches iron net, also comprise the power supply (6) being connected with iron net (2) and iron brush electrode (5).
2. the original position repair system that a kind of sustainable removal underground water Cr according to claim 1 pollutes, is characterized in that: also comprise that the ionogen being communicated with infiltration type reaction wall caisson (1) adds stirred vessel (7).
3. the original position repair system that a kind of sustainable removal underground water Cr according to claim 1 and 2 pollutes, is characterized in that: the virtual voltage of described power supply (6) is 0-50V, watt current is 0-5A.
4. the restorative procedure of the original position repair system that a kind of sustainable removal underground water Cr claimed in claim 2 pollutes, is characterized in that:
First synthetic Cr polluted water is flowed into from infiltration type reaction wall caisson (1) water-in, water outlet flows out, and when reaction reaches Preset Time, iron filler (4) is to Cr
6+clearance lower than set clearance time, after being iron filler (4) passivation, choosing (2) one jiaos, iron net is positive pole, iron brush electrode (5) is negative pole, after power supply (6) energising 1-30min, choose again another angle of iron net (2) for anodal, switch on the same time, finally put upside down again positive and negative electrode, switch on the same time, by additional certain electric field, one side of negative electrode, a large amount of hydrogen can be separated out in surface, and a large amount of bubbles break loose from iron filler (4) surface, adhesion layer on it is peeled off and scavenging(action), iron surface passivation layer is peeled off; The a large amount of strippings of one side iron ion of anode, peel off the precipitation on iron filler (4) surface;
In electrochemistry solution passivating process, when iron is as negative electrode and while having certain potential value, there is following electrochemical reaction, separate out a large amount of hydrogen:
Anode: 2H
2o → O
2+ 4H
++ 4e
-
Negative electrode: 2H
2o+2e
-→ H
2+ 2OH
-
When iron is during as anode, there is following electrochemical reaction, anode has iron ion and produces:
Anode: Fe → Fe
2++ 2e
-
Negative electrode: 2H
2o+2e-→ H
2+ 2OH
-(2) O
2+ 2H
2o+4e
-→ 4OH
-.
5. method according to claim 4, is characterized in that: in the time of energising, add stirred vessel (7) add anhydrous sodium sulphate as ionogen by ionogen in iron filler (4), the dosage of anhydrous sodium sulphate is 0.5g/L.
6. method according to claim 4, is characterized in that: in described synthetic Cr polluted water, Cr is 25mg/L; Na
2sO
4for 0.5g/L.
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| CN201310150256.6A CN103232096B (en) | 2013-04-26 | 2013-04-26 | In-situ repairing system and repairing method capable of continuously removing Cr in underground water |
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|---|---|---|---|
| CN201310150256.6A CN103232096B (en) | 2013-04-26 | 2013-04-26 | In-situ repairing system and repairing method capable of continuously removing Cr in underground water |
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| CN103232096B true CN103232096B (en) | 2014-07-23 |
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Families Citing this family (4)
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| CN105414160B (en) * | 2015-12-18 | 2018-06-15 | 江苏维尔利环保科技股份有限公司 | The devices and methods therefor of the repairing hexavalent chromium polluted underground water of up flow type PRB technologies |
| CN112110571A (en) * | 2020-09-23 | 2020-12-22 | 北京高能时代环境技术股份有限公司 | Permeable reactive barrier and repairing method |
| CN113929206B (en) * | 2021-11-22 | 2023-07-04 | 重庆大学 | Method and device for in-situ remediation of underground water pollution by electrically driven biological PRB |
| CN115231649B (en) * | 2022-07-11 | 2023-09-15 | 南京格洛特环境工程股份有限公司 | Method for removing perfluorinated compounds in underground water by photoelectrocatalysis synergistic PRB method |
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| US5326439A (en) * | 1993-02-24 | 1994-07-05 | Andco Environmental Processes, Inc. | In-situ chromate reduction and heavy metal immobilization |
| US6004451A (en) * | 1998-02-26 | 1999-12-21 | The Regents Of The University Of California | Electrochemical decomposition of soil and water contaminants in situ |
| CN100998987A (en) * | 2006-01-13 | 2007-07-18 | 南京大学 | Electric restoring method of polluted soil and underground water |
| CN102240667A (en) * | 2011-04-01 | 2011-11-16 | 重庆大学 | Electric remediation and reducing detoxication method for chromium contaminated soil and underground water |
| CN102874905A (en) * | 2012-10-15 | 2013-01-16 | 河海大学 | Device and method for repairing heavy metal polluted soil and underground water in situ |
| CN102897889A (en) * | 2012-10-29 | 2013-01-30 | 同济大学 | Method and device for purifying cadmium in waste water through nano zero-valent iron |
-
2013
- 2013-04-26 CN CN201310150256.6A patent/CN103232096B/en active Active
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5326439A (en) * | 1993-02-24 | 1994-07-05 | Andco Environmental Processes, Inc. | In-situ chromate reduction and heavy metal immobilization |
| US6004451A (en) * | 1998-02-26 | 1999-12-21 | The Regents Of The University Of California | Electrochemical decomposition of soil and water contaminants in situ |
| CN100998987A (en) * | 2006-01-13 | 2007-07-18 | 南京大学 | Electric restoring method of polluted soil and underground water |
| CN102240667A (en) * | 2011-04-01 | 2011-11-16 | 重庆大学 | Electric remediation and reducing detoxication method for chromium contaminated soil and underground water |
| CN102874905A (en) * | 2012-10-15 | 2013-01-16 | 河海大学 | Device and method for repairing heavy metal polluted soil and underground water in situ |
| CN102897889A (en) * | 2012-10-29 | 2013-01-30 | 同济大学 | Method and device for purifying cadmium in waste water through nano zero-valent iron |
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| CN103232096A (en) | 2013-08-07 |
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