CN102910709A

CN102910709A - In-situ remediation method for organic contaminated underground water

Info

Publication number: CN102910709A
Application number: CN2012104303786A
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: 2013-02-06
Anticipated expiration: 2032-11-01
Also published as: CN102910709B

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 regulate and control persulfate (S by regulating the ferroelectric polarity that extremely goes up and size of current ₂O ₈ ^2-) to the oxidation activity of organic pollutant to realize the 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 that is widely adopted, but a lot of urban groundwater polluted in various degree, and wherein the pollution that causes of toxic organic compound such as hydrochloric ether is particularly serious, and total body pollution situation is very severe.In groundwater pollution, the small area contaminated sites underground water take the source pollution as feature is because pollution level is high and harm seriously has been subject to showing great attention to.Therefore repair significant to the contaminated site underground water that caused by toxic organic compound.

The reparation of contaminated site underground water came into one's own in developed country from the eighties in last century, and China still is in the starting stage at present.Because high density feature and the repairing efficiency requirement of contaminated site, in situ chemical oxidation (ISCO) owing to an important recovery technique of repairing fast and implementing conveniently to become in recent years, are thought to repair innovating technologies of " brown ground " by U.S. EPA.Traditional oxygenant mainly comprises H ₂O ₂, O ₃With MnO4 etc., although repairing effect is good, because the loss that the active high side reaction of these oxygenants causes is larger, so that effective rate of utilization is 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 is used.S ₂O ₈ ^2-Although have higher oxidizing potential, itself and organic reaction kinetics process are extremely slow, thereby have preferably stability, and the loss in course of conveying is minimum.S ₂O ₈ ^2-Behind overactivation, can produce SO ₄ ^-, have the oxidation capacity suitable with OH.Thereby, S ₂O ₈ ^2-The key of oxidation reparation is S ₂O ₈ ^2-Activation.

In the site remediation to S ₂O ₈ ^2-Activation method commonly used comprise the activation of thermal activation, alkali and Fe (II) activation.Thermal activation needs water temp. heating is arrived comparatively high temps (such as 50 ^oMore than the C), the alkali activation needs more than the pH regulator to 12, and these two kinds of activation methods have increased rehabilitation cost and difficulty, S ₂O ₈ ^2-Also can inevitably occur to decompose before the arrival zone of pollution and cause losing.Comparatively speaking, Fe (II) (containing the chelating attitude) priming reaction condition is more gentle, but the absorption of Fe (II) in transmission course, oxidation, precipitation etc. also can cause damage, greatly reduce effective propagation path, and the Fe (II) of initial injection stage high density also can consume oxygenant.In addition, S ₂O ₈ ^2-After priming reaction was complete, the pH of system can be reduced to 2 – 3, caused the release risk of heavy metal in the underground environment.

In present persulfate oxidation is repaired, have following problem: 1. present activation method can only improve the oxidation activity of persulfate, in case just can't regulate active size after persulfate is activated, more can't suppress or eliminate activity, this certainly will cause a large amount of persulfate can't be utilized and be wasted when Pollutant levels are low.2. it is underground that activator mixes rear injection with persulfate solution, can't realize the in-situ activation after persulfate is transferred to Polluted area.The decomposition of persulfate with activator mix after begin immediately, thereby injecting underground and all can causing the decomposition loss of persulfate in the transmission course of underground environment, reduced the utilization ratio of persulfate.3. self decompose the sulfuric acid that produces after the persulfate oxidation 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 attitude 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 (strengthening and inhibition) and heavy metal that the method has solved persulfate activity in the reparation of persulfate in situ chemical oxidation discharge a difficult problem.

Realize that the technical scheme that the object of the invention adopts is to regulate and control persulfate S by regulating the ferroelectric polarity that extremely goes up and size of current ₂O ₈ ^2-To realize the original position reparation to organic contamination underground water, concrete grammar is as follows to the oxidation activity of organic pollutant: S is injected in the organic contamination zone to underground water ₂O ₈ ^2-, the ferroelectric utmost point of energising is inserted in this Polluted area, provide ferrous ion Fe (II) by regulating the ferroelectric size of current that extremely goes up, the ferroelectric utmost point is partly dissolved and produces Fe (II) thereby activation S during ferroelectric extremely logical positive current ₂O ₈ ^2-Thereby make the ferroelectric utmost point be in passive state inhibition even termination S during ferroelectric extremely logical negative current ₂O ₈ ^2-Reactive behavior; Work as S ₂O ₈ ^2-After being exhausted, the ferroelectric utmost point is continued electrolysis as anode provides Fe ^2/3+And OH ^-Thereby improve the pH of system to neutral.

Its more specifically step that adopts 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 zone in the 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, make Sodium Persulfate concentration in this Polluted area be 15 times of 3 – of organic contamination substrate concentration in this Polluted area;

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

4., the raising of underground water pH value and reparation: after the pollutent decomposition is complete, continuation applies positive current to the ferroelectric utmost point, and raising is applied to ferroelectric current value to the 0.1 – 1A that extremely goes up, the pH variation of monitoring underground water, namely stop energising more than 6.0 when pH brings up to, finish repair process.

The present invention directly inserts the ferroelectric utmost point to the groundwater pollution zone as shown from the above technical solution, and the realization in-situ activation has been avoided the decomposition loss in persulfate injection and the course of conveying; By polarity and the size of current that changes 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 the prolongation electrolysis time, the pH after the raising reparation is complete avoids the quadratic risk function of underground water acidifying and heavy metal release to neutral.

Compare with existing persulfate activation method, progressive meaning of the present invention is: 1. the activated positions with persulfate changes to the groundwater pollution zone, has reduced the loss in persulfate injection and the transmission course; 2. can regulate flexibly the activity of persulfate, except activating, in repair process, can also suppress even eliminate the activity of persulfate.3. alleviate even avoided the acidifying of underground water after the persulfate oxidation and heavy metal to discharge quadratic risk function.

Description of drawings

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

Heavy metal concentration change curve when Fig. 2 is ferroelectric utmost point activation persulfate degraded TCE.

PH value of solution and ORP change curve when Fig. 3 is ferroelectric utmost point activation persulfate degraded TCE.

Embodiment

Embodiment 1:

Simulated groundwater Organic pollutants zone in sealed reactor, trieline (TCE) and the Na of the 52mg/L of adding 410mL in reactor ₂S ₂O ₈, Na ₂S ₂O ₈Concentration is 12.5 times of TCE concentration, (long * wide * high=76 * 9.5 * 3.2mm) and titanium net (length * wide * height=85 * 15 * 1.8 mm) serve as two electrodes to insert iron plate, distance between two electrodes is 2 – 30cm, use wire electrode to be connected to two output terminals of constant voltage dc source, after the sealing take iron plate as anodal and apply the positive current of 50mA, persulfate is activated, thereby realize organic oxidative degradation, current value can be regulated between 10 – 500mA in the degradation process, when the organic pollutant reparation reaches 95% mass percent, changing iron is negative pole and the negative current that applies 50mA, suppress persulfate active, current value can be regulated between 50 – 200mA in the process of inhibition, after the pollutent decomposition is complete, continue to apply the 100mA positive current to the ferroelectric utmost point, the pH of monitoring underground water changes, namely stop energising more than 6.0 when pH brings up to, finish 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, (long * wide * high=76 * 9.5 * 3.2mm) and titanium net (length * wide * height=85 * 15 * 1.8 mm) serve as two electrodes to insert the cast iron sheet, change is applied to the ferroelectric polarity of electrode of extremely going up and size of current after the sealing, and 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, reach when applying negative current-degraded of TCE is almost suppressed fully during 50mA.

Comparison embodiment 2:

Use identical reactor, in another group test, reduce Na ₂S ₂O ₈Concentration, for TCE concentration 4 times are continuously applied+100mA to 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, TCE is by degradable behind the 30min, continuation applies+the 100mA electric current to the ferroelectric utmost point, and persulfate concentration concentration continues to reduce, and 50min begins free state heavy metal copper ion (Cu ²⁺) concentration begins remarkable reduction.PH and the redox potential (ORP) corresponding by Fig. 3 change as can be known, and the pH of the aqueous solution begins remarkable increase during 50min, and reaches neutral range when 90min.

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

Claims

1. the in-situ remediation method to organic contamination underground water is characterized in that regulating and control persulfate S by regulating the ferroelectric polarity that extremely goes up and size of current ₂O ₈ ^2-To realize the original position reparation to organic contamination underground water, concrete grammar is as follows to the oxidation activity of organic pollutant: S is injected in the organic contamination zone to underground water ₂O ₈ ^2-, the ferroelectric utmost point of energising is inserted in this Polluted area, provide ferrous ion Fe (II) by regulating the ferroelectric size of current that extremely goes up, the ferroelectric utmost point is partly dissolved and produces Fe (II) thereby activation S during ferroelectric extremely logical positive current ₂O ₈ ^2-Thereby make the ferroelectric utmost point be in passive state inhibition even termination S during ferroelectric extremely logical negative current ₂O ₈ ^2-Reactive behavior; Work as S ₂O ₈ ^2-After being exhausted, the ferroelectric utmost point is continued electrolysis as anode provides Fe ^2/3+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:

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