CN102910709B

CN102910709B - In-situ remediation method for organic contaminated underground water

Info

Publication number: CN102910709B
Application number: CN201210430378.6A
Authority: CN
Inventors: 袁松虎; 廖鹏; 艾克元爱沙瓦比克
Original assignee: China University of Geosciences
Current assignee: China University of Geosciences
Priority date: 2012-11-01
Filing date: 2012-11-01
Publication date: 2014-06-04
Anticipated expiration: 2032-11-01
Also published as: CN102910709A

Abstract

The invention relates to an in-situ remediation method for organic contaminated underground water, comprising the specific steps that S2O8<2-> is injected to the organic contaminated region of underground water, an electrified iron electrode is inserted into the organic contaminated region, Fe (II) is provided by regulating the current magnitude of the iron electrode, when the iron electrode is electrified by positive current, the iron electrode partially is dissolved and generates Fe (II), so that S2O8<2-> is activated; when the iron electrode is electrified by negative current, the iron electrode is in the passivation state, so that the reaction activity of S2O8<2-> is restrained and even terminated; and when S2O8<2-> is used up, the iron electrode is used as the anode to continuously electrolyze, so as to provide Fe<2/3+> and OH<->, so that the pH of the system is increased to neutral state. The in-situ remediation method solves the difficult problems of in-situ regulation (enhancing and restraining) on the activity of peroxydisulfate and heavy metal release in the in-situ chemical oxidization remediation of peroxydisulfate.

Description

A kind of in-situ remediation method to organic contamination underground water

Technical field

The present invention relates to a kind of in-situ remediation method to organic contamination underground water, especially by regulating the ferroelectric polarity extremely going up and size of current to regulate and control persulfate (S ₂o ₈ ^2-) to the oxidation activity of organic pollutant to realize in-situ remediation method to organic contamination underground water, belong to underground water recovery technique field.

Background technology

Underground water is the drinking water source being widely adopted, but much urban groundwater is polluted in various degree, and wherein toxic organic compound is as particularly serious in the pollution that hydrochloric ether causes, total body pollution situation is very severe.In groundwater pollution, the small area contaminated sites underground water take source pollution as feature, because pollution level is high and harm has seriously been subject to showing great attention to.Therefore to being subject to the contaminated site underground water that toxic organic compound causes to repair significant.

The reparation of contaminated site underground water comes into one's own in developed country from the eighties in last century, and China is at present still in the starting stage.Due to high density feature and the repairing efficiency requirement of contaminated site, in situ chemical oxidation (ISCO), owing to repairing fast and implementing conveniently to become an important recovery technique in recent years, is thought to repair innovating technologies of " palm fibre ground " by U.S. EPA.Traditional oxygenant mainly comprises H ₂o ₂, O ₃with MnO4 etc., although repairing effect is good, the loss causing due to the high side reaction of activity of these oxygenants is larger, makes effective rate of utilization lower.Persulfate (S ₂o ₈ ^2-) be a kind of emerging site remediation oxygenant, because its unique oxidation susceptibility is paid attention to rapidly and applies.S ₂o ₈ ^2-although have higher oxidizing potential, itself and organic reaction kinetics process are extremely slow, thereby have good stability, and the loss in course of conveying is minimum.S ₂o ₈ ^2-after overactivation, can produce SO ₄ ^-, there is the oxidation capacity suitable with OH.Thereby, S ₂o ₈ ^2-the key that oxidation is repaired is S ₂o ₈ ^2-activation.

In site remediation to S ₂o ₈ ^2-conventional activation method comprise the activation of thermal activation, alkali and Fe (II) activation.Thermal activation need be arrived comparatively high temps (as 50 by water temp. heating ^omore than C), alkali activation need be by more than pH regulator to 12, and these two kinds of activation methods have increased rehabilitation cost and difficulty, S ₂o ₈ ^2-before arrival zone of pollution, also can inevitably occur to decompose and cause losing.Comparatively speaking, Fe (II) (containing chelating state) priming reaction condition is more gentle, but the absorption of Fe (II) in transmitting procedure, oxidation, precipitation etc. also can cause damage, greatly reduce effective propagation path, and the Fe (II) of initial injection stage high density also can oxygen consumed agent.In addition, S ₂o ₈ ^2-after priming reaction, the pH of system can be reduced to 2 – 3, causes the release risk of heavy metal in underground environment.

In current persulfate oxidation is repaired, there is following problem: 1. current activation method can only improve the oxidation activity of persulfate, once just cannot regulate active size after persulfate is activated, more cannot suppress or eliminate activity, in Pollutant levels, this certainly will cause a large amount of persulfate cannot be utilized and be wasted when low.2. it is underground that activator mixes rear injection with persulfate solution, cannot realize persulfate and be transferred to the in-situ activation after Polluted area.The decomposition of persulfate with activator mix after start immediately, thereby injecting underground and all can causing the decomposition loss of persulfate in the transmitting procedure of underground environment, reduced the utilization ratio of persulfate.3. after persulfate oxidation, self decompose the sulfuric acid producing and the pH of restoring area underground water can be reduced to 2 – 3, thereby cause that the total heavy metal desorb of underground environment Minerals surface adsorption state heavy metal and minerals discharges, and causes the quadratic risk function of underground water acidifying and heavy metal contamination.

Summary of the invention

For overcoming the deficiency of above-mentioned prior art, the invention provides a kind of in-situ remediation method to organic contamination underground water, original position regulation and control (strengthen and suppress) and heavy metal that the method has solved persulfate activity in the reparation of persulfate in situ chemical oxidation discharge a difficult problem.

Realizing the technical scheme that the object of the invention adopts is by regulating the ferroelectric polarity extremely going up and size of current to regulate and control persulfate S ₂o ₈ ^2-to the oxidation activity of organic pollutant, to realize the original position reparation to organic contamination underground water, concrete grammar is as follows: S is injected in the organic contamination region to underground water ₂o ₈ ^2-, the ferroelectric utmost point of energising is inserted in this Polluted area, by regulating the ferroelectric size of current extremely going up that ferrous ion Fe (II) is provided, when ferroelectric extremely logical positive current, the ferroelectric utmost point is partly dissolved and produces Fe (II) thereby activation S ₂o ₈ ^2-; Thereby make the ferroelectric utmost point suppress even to stop S in passive state when ferroelectric extremely logical negative current ₂o ₈ ^2-reactive behavior; Work as S ₂o ₈ ^2-after being exhausted, continuing electrolysis using the ferroelectric utmost point as anode provides Fe ^2/3+and OH ^-thereby improve the pH of system to neutral.

Its more specifically step adopting is:

1., electrode is selected and is installed: use iron staff or iron plate and titanium rod or titanium sheet or titanium net as two electrodes, directly insert the organic contamination region in waterbearing stratum, distance between two electrodes is 2 – 30cm, uses wire electrode to be connected to two output terminals of constant voltage dc source;

2., persulfate injection of solution: directly inject Sodium Persulfate solution to Polluted area, making Sodium Persulfate concentration in this Polluted area is 15 times of 3 – of organic contamination substrate concentration in this Polluted area;

3., persulfate activity regulation implements with repairing: when persulfate is transferred to after Polluted area, take iron as anodal and apply the positive current of 10 – 500mA, persulfate is activated, thereby realize organic oxidative degradation; By regulating the size of positive current, regulate the activation degree of persulfate; When organic pollutant reparation reaches mass percent 95% when above, changing iron is negative pole the negative current that applies 50 – 200mA, suppresses even to eliminate persulfate activity;

4., the raising of underground water pH value and reparation: after pollutent decomposes, continue to apply positive current to the ferroelectric utmost point, and raising is applied to ferroelectric current value to the 0.1 – 1A extremely going up, the pH variation of monitoring underground water, stop energising when pH brings up to more than 6.0, complete repair process.

The present invention directly inserts the ferroelectric utmost point to groundwater pollution region as shown from the above technical solution, realizes in-situ activation and has avoided the decomposition loss in persulfate injection and course of conveying; By changing polarity and the size of current of the ferroelectric utmost point, can reach the oxidation activity that strengthens or suppress persulfate, so can regulate targetedly according to Pollutant levels the activity of persulfate, improve the utilization ratio of persulfate; By using iron anode and improving electric current and prolongation electrolysis time, the pH after raising is repaired, to neutral, avoids the quadratic risk function of underground water acidifying and heavy metal release.

Compared with existing persulfate activation method, progressive meaning of the present invention is: 1. the activated positions of persulfate is changed to groundwater pollution region, reduced the loss in persulfate injection and transmitting procedure; The activity that 2. can regulate flexibly persulfate except activating, can also suppress even to eliminate the activity of persulfate in repair process.3. alleviate and even avoided acidifying and the heavy metal of the rear underground water of persulfate oxidation to discharge quadratic risk function.

Accompanying drawing explanation

Fig. 1 applies the influence curve figure to persulfate degraded TCE under different electric currents to the ferroelectric utmost point.

Heavy metal concentration change curve when Fig. 2 is iron electrode activation persulfate degraded TCE.

PH value of solution and ORP change curve when Fig. 3 is iron electrode activation persulfate degraded TCE.

Embodiment

Embodiment 1:

Simulated groundwater Organic pollutants region in sealed reactor adds trieline (TCE) and the Na of the 52mg/L of 410mL in reactor ₂s ₂o ₈, Na ₂s ₂o ₈concentration is 12.5 times of TCE concentration, insert iron plate (length × wide × height=76 × 9.5 × 3.2mm) and titanium net (length × wide × height=85 × 15 × 1.8 mm) and serve as two electrodes, distance between two electrodes is 2 – 30cm, use wire electrode to be connected to two output terminals of constant voltage dc source, after sealing take iron plate as anodal and apply the positive current of 50mA, persulfate is activated, thereby realize organic oxidative degradation, in degradation process, current value can regulate between 10 – 500mA, in the time that organic pollutant reparation reaches 95% mass percent, changing iron is negative pole the negative current that applies 50mA, suppress persulfate activity, in process of inhibition, current value can regulate between 50 – 200mA, after pollutent decomposes, continue to apply 100mA positive current to the ferroelectric utmost point, the pH of monitoring underground water changes, when bringing up to more than 6.0, pH stops switching on, complete repair process.

Comparison embodiment 1:

In sealed reactor simulation Organic pollutants waters, in container, add trieline (TCE) and the Na of the 52mg/L of 410mL ₂s ₂o ₈, Na ₂s ₂o ₈concentration is 12.5 times of TCE concentration, insert cast iron sheet (length × wide × height=76 × 9.5 × 3.2mm) and titanium net (length × wide × height=85 × 15 × 1.8 mm) and serve as two electrodes, after sealing, change and be applied to the ferroelectric polarity of electrode of extremely going up and size of current, the removal effect of TCE as shown in Figure 1.Clearly, the degradation effect of TCE accelerates with the increase of positive current, is suppressed more significantly with the increase of negative current, and in the time of the reach-50mA that applies negative current, the degraded of TCE is almost suppressed completely.

Comparison embodiment 2:

Use identical reactor, in another battery of tests, reduce Na ₂s ₂o ₈concentration, is 4 times of TCE concentration, to be continuously applied+100mA of the ferroelectric utmost point.Experimental result as shown in Figure 2, as shown in Figure 2, TCE and persulfate concentration changes with time and significantly reduce, after 30min, TCE is completely degraded, continue to apply+100mA of ferroelectric utmost point electric current, persulfate concentration concentration continues to reduce, and 50min starts free state heavy metal copper ion (Cu ²⁺) concentration starts remarkable reduction.Changed from pH corresponding to Fig. 3 and redox potential (ORP), when 50min, the pH of the aqueous solution starts remarkable increase, and reaches neutral range in the time of 90min.

Can use other material in chlorinated solvent, benzene homologues and polycyclic aromatic hydrocarbons to replace the pollutent TCE in above-described embodiment, can obtain equally similar experimental result.

Claims

1. the in-situ remediation method to organic contamination underground water, is characterized in that by regulating the ferroelectric polarity extremely going up and size of current to regulate and control persulfate S ₂o ₈ ^2-to the oxidation activity of organic pollutant, to realize the original position reparation to organic contamination underground water, concrete grammar is as follows: S is injected in the organic contamination region to underground water ₂o ₈ ^2-, the ferroelectric utmost point of energising is inserted in this Polluted area, by regulating the ferroelectric size of current extremely going up that ferrous ion Fe is provided ²⁺, when ferroelectric extremely logical positive current, the ferroelectric utmost point is partly dissolved and produces Fe ²⁺thereby activation S ₂o ₈ ^2-; Thereby make the ferroelectric utmost point suppress even to stop S in passive state when ferroelectric extremely logical negative current ₂o ₈ ^2-reactive behavior; After pollutent decomposes, continuing electrolysis using the ferroelectric utmost point as anode provides Fe ²⁺, Fe ³⁺and OH ^-thereby improve the pH of system to neutral.

2. the in-situ remediation method to organic contamination underground water according to claim 1, is characterized in that adopting following concrete steps:

(1) electrode is selected and is installed: use iron staff or iron plate and titanium rod or titanium sheet or titanium net as two electrodes, directly insert the organic contamination region in waterbearing stratum, distance between two electrodes is 2 – 30cm, uses wire electrode to be connected to two output terminals of constant voltage dc source;

(2) persulfate injection of solution: directly inject Sodium Persulfate solution to Polluted area, making Sodium Persulfate concentration in this Polluted area is 15 times of 3 – of organic contamination substrate concentration in this Polluted area;

(3) persulfate activity regulation is implemented with repairing: when persulfate is transferred to after Polluted area, take iron as anodal and apply the positive current of 10 – 500mA, persulfate is activated, thereby realize organic oxidative degradation; By regulating the size of positive current, regulate the activation degree of persulfate; When organic pollutant reparation reaches mass percent 95% when above, changing iron is negative pole the negative current that applies 50 – 200mA, suppresses even to eliminate persulfate activity;

(4) raising of underground water pH value and reparation: after pollutent decomposes, continue to apply positive current to the ferroelectric utmost point, and raising is applied to ferroelectric current value to the 0.1 – 1A extremely going up, the pH variation of monitoring underground water, stop energising when pH brings up to more than 6.0, complete repair process.

3. the in-situ remediation method to organic contamination underground water according to claim 1, is characterized in that: described organic pollutant is chlorinated solvent, benzene homologues or polycyclic aromatic hydrocarbons.