A kind of soil remediation method of handling heavy metal contaminants
Technical field
The present invention relates to a kind of soil remediation method, relate to a kind of soil remediation method of handling metal pollutant especially, belong to the soil remediation method field.
Background technology
The characteristic of several heavy metal pollutions:
1, cadmium (Cd)
Cadmium (Cd) is a kind of argenteous rare metal, and the quality softness is rich in ductility, and is anticorrosive, wear-resisting, hot a little volatile.Now do not find independent cadmium ore deposit, find in the plumbous zinc of being everlasting, the lead bronze zinc ore.Cadmium is widely used in industries such as plating, automobile and aviation, pigment, paint, printing.Recent study proves, no matter is from toxicity or cumulative effect, and cadmium all will be the 3rd metallic element that pollutes human environment, threat human health after mercury, lead.Owing to cadmium applied range, consumption pattern variation, increased the chance of environmental pollution, cadmium has caused common concern to the pollution of environment at present, the control cadmium pollution has become the synthtic price index of the whole society.
2, copper (Cu)
Copper (Cu) is biological essential nutrient, and an amount of copper all is useful to people and animals and plants, but excessive copper works the mischief to growing of biology, and its surrounding enviroment are produced heavy damage.In addition, along with the fast development of industrial and agricultural production, the purposes of copper more and more widely, consumption constantly increases, the cupric pollutant emission is more and more, and the pollution of soil environment is also displayed gradually.Therefore, in recent years, the research that soil-plant system copper is polluted has caused people's attention with improvement.
3, plumbous (Pb)
Plumbous (Pb) solubility in soil is low, and is difficult for moving, but owing to human the continually developing and destroying of nature added industrial expansion, has caused serious day by day global lead contamination.The plumbous characteristics that the toxic action of human body had latency and chronicity.Because the continuous generation of lead poisoning incident, the research of relevant lead contamination and lead poisoning evil more and more is subjected to the attention of Chinese scholars.
4, mercury (Hg)
Mercury (Hg) can enter soil environment by different approaches, Hg in the soil is through complicated physics, chemical reaction, major part is trapped in the soil with various forms, and Hg accumulates and enter the food chain circulation at the crop edible part simultaneously, and health is constituted a threat to.There is 3.2 * 104ha in China by the cultivated area that Hg pollutes, and the annual Hg that produces contaminated environment reaches 1.9 * 108kg.Soil is polluted by Hg in a single day, and human health is constituted potential harm, so improvement and bioremediation technology research that soil Hg pollutes are outstanding apparent important.
Use recovery technique both at home and abroad always
Heavy metal pollution of soil has disguise, chronicity and irreversibility, the holdup time of pollutant in soil is long, plant or microorganism can not be degraded, heavy metal pollution not only causes the reduction of degeneration, crop yield and the quality of soil, and may jeopardize human life and health by direct contact, food chain.
At present, broad research is all being carried out to the heavy metal pollution of soil recovery technique in countries in the world, and its main path has 3 kinds: 1. change the heavy metal state, reduce its activity, make its passivation, break away from food chain, reduce its toxicity; 2. utilize the heavy metal in the hyperaccumulative plant absorption soil; 3. with engineering heavy metal is become soluble state, free state, pass through drip washing again, collect the heavy metal in the leacheate then, thereby reach the purpose that reclaims heavy metal and reduce heavy metal in soil content.At these three kinds of approach, its concrete method generally can be divided following several measure: engineering reclamation activities, chemical reclamation activities, agricultural measures and biological restoration measure etc.
One, engineering recovery technique
(1) physics reparation
Physical measure mainly comprises soil moved in to improve the original, soil removal and replacement, go to show soil and deep ploughing is digged.1. soil moved in to improve the original method-be exactly adds a large amount of clean soils to contaminated soil, covers top layer or mixing, and it is following or reduce the extraneous contact of pollutant to make the heavy metal pollution substrate concentration be reduced to harm concentration, alleviates harm, can not reduce the total amount of heavy metal; 2. soil replacement method---contaminated by heavy metals soil is taken away, changed to new free of contamination soil.This method occur small size severe contamination and pollutant tool radioactivity or easily diffusion difficult decompose situation under use morely, be a kind of pollution transportation method; 3. digging is exactly to plough deeply heavy-metal contaminated soil, makes the pollutant that accumulates in the top layer be distributed to darker level, reaches the purpose of dilution, and same, this method has just reduced heavy metal in soil concentration, and total metals does not reduce.
(2) electric repairing technique
The electronic reparation of soil is a new soil remediation method, its principle mainly is to form electric-force gradient by apply DC electric field on the pollution soil body, and pollutant in soil is taken out of soil by approach such as electromigration, EOF or electrophoresis finally makes contaminated soil be cleaned.This technology is very effective at clay and the heavy metals such as the lead in the silt soil, arsenic, chromium, cadmium, copper, uranium, mercury and zinc of removing hypotonicity, has experiment to show that this method is to Pb in the soil
2+, Cr
3+The rate of removing etc. heavy metal ion also can reach more than 90%.This method is suitable for the clay and the silt soil of hyposmosis, can control the flow direction of pollutant.Electronic recovery project is implemented more complicated, invests higherly, and operating cost is higher, but this technology is a kind of based technique for in-situ remediation, does not stir soil layer, and can shorten repair time, thereby is a kind of recovery technique with development potentiality.
(3) electric heating recovery technique
The electric heating reparation is to utilize high frequency voltage to generate electromagnetic waves and heat, and soil is heated, and pollutant is desorbed in soil particle, accelerates some effumability heavy metals and separates from soil, thereby reach the purpose of reparation.This technology can be repaired by the soil of heavy metal pollutions such as Hg and Se.Can place heavy metal pollution district soil under the HTHP in addition, form glass state material, the cooling back forms stiff glass body chemically inert, non-diffusion, thereby reach the purpose of fundamentally eliminating heavy metal pollution of soil, Ida. engineering test in 1991 each heavy metal species refuse (As, Ag, Ba, Cd etc.) landfill after 0.66m is underground, use the vitrifying method, fixed heavy metal contaminants, proved the feasibility of this technology.This method technology is simple, but energy consumption is big, and the operating cost height easily forms uncontrollable secondary pollution.
(4) soil drip washing technology
Soil drip washing measure, its principle is the heavy metal effect in utilization reagent and the solid phase of soil, form deliquescent heavy metal ion or metal complex, with clear water pollutant is dashed to the root layer then, utilize the compound that contains certain ligand to dash again and drench soil, make it to form more stable complex compound with heavy metal ion; Or,, make heavy metal form compound precipitation as carbonate, phosphate flushing soil with having anionic solution.At present, the leacheate of available soil is more, comprises organic or inorganic acid, alkali, salt and intercalating agent.This technology is simple to operate, invests lowlyer, can effectively reduce heavy metal in soil concentration, but needs to consider the collection and the processing of leacheate, avoids secondary pollution.
Two, chemistry is repaired
The chemistry reclamation activities is actual to be a kind of soil based technique for in-situ remediation, be exactly to throw people's modifying agent or activating agent to soil, make its Acidity of Aikalinity that changes soil, redox conditioned disjunction ion constitute situation, and then absorption, redox, antagonism or the precipitation of heavy metal exerted an influence, finally reduce the pollution of heavy metal.Modifying agent commonly used has the organic substance of lime, zeolite, calcium carbonate, phosphate, silicate and promotion reduction etc.
(1) chemical improvement agent recovery technique
Chemical improvement agent is repaired, and for the acid ground that is subjected to heavy metal pollution, basic species mass-energy such as liming improve soil pH value, reduce the dissolubility of heavy metal.On the Cd contaminated soil, use alkaline matter such as lime, make heavy metal in soil Cd available state content reduce about 15%, had certain effect by crop absorption tool reducing Cd.Zeolite also can be used as soil conditioner, the harmful substance in the fixing soil, the possibility of minimizing plant absorbing.This technology can only be improved the contaminated degree of soil, does not reduce total metals.
(2) surface-active cleaning agent recovery technique
The surface-active cleaning agent is repaired, utilize characteristics such as surfactant is wetting, solubilising, dispersion, washing, change the soil surface electric charge and absorb potential energy, or heavy metal is cemented out from soil surface, form with complexing, chelate is present in the soil liquid, accelerates the flowability of heavy metal in the soil liquid.The auxiliary reclamation activities of the present Chang Zuowei of this technology is used, and has certain uncontrollability.
(3) heavy metal antagonist recovery technique
Heavy metal antagonist is repaired, according to the antagonism between the heavy metal element in the soil environment, have antagonism as heavy metal and Sn, As, elements such as Zn, Cu, utilize some that human body is safe from harm or the antagonism of useful metallic element, reduce the available state of heavy metal in soil.Therefore, in light contaminated soil, use a spot of heavy metal antagonist, can play good preventive and therapeutic effect.
Three, biological restoration
Biological restoration is that the biotechnology of utilizing that grows up early 1990s is administered a kind of new method of contaminated soil.Its basic principle is the toxicity of utilizing the heavy metal in specific plant, animal or microorganism reduction, the purification soil or reducing heavy metal.This method is a kind of original position reparation, and cost is low, and is effective, and easy operating is subject to people's attention day by day, becomes the focus of contaminated soil reparation research.Biological restoration is divided into three kinds of phytoremediation, microorganism reparation and animal reparations etc. again.
(1) phytoremediation technology
Phytoremediation technology can be divided into that plant extract, phytovolatilization, rhizosphere are filtered and plant fixing etc.Generally former three is referred to as the removal process, it relies on hyperaccumulative plant can absorb, transport and restrain oneself the high-load heavy metal in its whole life; And the latter is called stabilization process, it is to utilize intercalating agent to promote the absorption of plant to heavy metal.What research was maximum now is the plant extract technology.
The plant extract technology promptly utilizes heavy metal hyperaccumulative plant to draw metal pollutant from soil, gathers in overground part subsequently and focuses on, and plants this plant continuously, reaches the purpose that reduces or remove heavy metal pollution of soil.Found that at present hundreds of ultraproducts tire out the heavy metal plant, can accumulate heavy metals such as Cr, Co, Ni, Cu, Pb.
The mechanism of phytovolatilization is to utilize root system of plant to absorb metal, is translated into gaseous material and evaporate in the atmosphere, to reduce soil pollution.Certain plants on the wetland can be removed the Se in the soil edge, and wherein simple substance accounts for 75%, and the volatilization attitude accounts for 20%~25%.
Plant stability is to utilize anti-heavy metal plant or super accumulation plant to reduce the activity of heavy metal, thus reduce heavy metal by drip washing to underground water or spread the possibility of further contaminated environment by air.Its mechanism mainly is to absorb the curing of strengthening heavy metal in soil by metal at accumulation, precipitation or the root table of root.Secretions from plant roots can change the rhizosphere soil environment, and the valence state of Cr, Hg, As and form are changed, and influences its poisonous effect; In addition, the root hair of plant can directly be fixed from soil exchange absorption heavy metal increase root table.
Utilize the enrichment of plant to heavy metal, the mode by harvesting is handled can effectively reduce the heavy metal in soil total amount, reaches the effect of reparation, thereby is a kind of widely used treatment technology.
(2) animal recovery technique
Some lower animal such as earthworm, muroid etc. can absorb the heavy metal in the soil in the soil, and then have reduced the content of heavy metal in the contaminated soil.Simultaneously, earthworm also can increase the efficient of plant absorbing heavy metal by increasing the heavy metal-polluted soil activity.There are some researches show that earthworm movement can obviously improve the biological effectiveness of red soil Cu, the content of DTPA extraction attitude Cu in the red soil is significantly increased, thereby improve absorption and the bioaccumulation efficiency of plant heavy metal.To the mode that the absorption and the vermis of heavy metal separates, can effectively reduce the concentration of heavy metal in soil by earthworm from soil, reach the target of reparation.
(3) microorganism recovery technique
Microorganism recovery technique, microorganism have unique effect aspect restoration of soil polluted by heavy metal.Its main action principle is: microorganism can reduce toxicity, absorption accumulation heavy metal, the change rhizosphere environment of heavy metal in soil, thereby improves absorption, volatilization or the fixed efficiency of plant to heavy metal.Microorganism also can be by improving soil aggregate, the physicochemical property of improving the soil and influencing process remote-effects heavy metal forms such as plant roots secretion.But, can't separate and collection, thereby to reducing the not directly effect of heavy metal in soil total amount because microorganism survives in soil always.
The comparison of above-mentioned technology path
Table 1: the pluses and minuses of various recovery techniques relatively
Summary of the invention
Technical problem to be solved by this invention provides a kind of soil remediation method of handling heavy metal contaminants, what more specifically provide a kind of economical rationality can effectively reduce the heavy metal in soil total amount, and to intending repairing the pollution-free and destruction in place, environment amenable soil remediation method.
The technical scheme that the present invention will provide is: a kind of soil remediation method of handling heavy metal contaminants, press the content of beary metal height in the soil, soil is divided into three classes, be serious pollution soil, intermediate pollution soil and light contamination soil, described soil remediation method at serious pollution soil comprises and carries out chemical leaching earlier, carries out earthworm bioaccumulation reparation and phytoremediation again; Described soil remediation method at intermediate pollution soil comprises earthworm bioaccumulation reparation and phytoremediation; Described soil remediation method at light contamination soil is a phytoremediation;
Described earthworm bioaccumulation repair process:
1), applies stalk and dried cow dung class fertilizer with the soil scarifying;
2) put into vermiculture, earthworm ingests by ceaselessly wriggling, related earth is taken in the body, make heavy metal stop in vivo and enrichment, during every day water, repair process waters one time water every day at least, when temperature is lower than 5 ℃, mulching straw and film keep the soil moisture, play interception simultaneously; When temperature is higher than 32 ℃, increase the frequency of watering, guarantee that moisture content is 60~70%.
3) collect vermis, adopt the natural lighting collecting method, 24h waters in advance, and the soil with the upper strata concentrates on cement flooring or the Polypropylence Sheet again, successively push aside, soil is scratched clean, make earthworm concentrate on bottom, reach the collection purpose, and, collect back soil and go back to the shop vermis and soil sieving separating; After three months, again depth of soil 20cm is collected with interior one-tenth earthworm;
Through above-mentioned steps 1), 2), 3) processing cycle of promptly finishing an earthworm bioaccumulation, a processing cycle is 3 months, carries out four processing cycles altogether;
Described chemical leaching is selected to contain the acid solution of chelating agent as eluent;
Described phytoremediation is selected Indian mustard and two kinds of plants of ramie for use; With three months be a season, autumn and winter plantations Indian mustard, two seasons of spring and summer plantation ramie after per season plantation finishes, connects root and collects, the plantation of digging again, the interpolation fertilizer, finishing the phytoremediation cycle is 18 months.
Preferably, the collection vermis of the step 3) of described earthworm bioaccumulation repair process, vermis was collected and was once become earthworm in one month summer, and each first quarter moon was collected and was once become earthworm other seasons.
Preferably, a processing cycle is added a fertilizer in the described earthworm bioaccumulation repair process, and addition is 35~40kg/m first
2, each thereafter addition is 20~25kg/m
2
Preferably, described earthworm is selected big flat No. 2 earthworm earthworm kinds for use.
Preferably, described chemical leaching comprises: polluted soil is excavated and move to treatment pond, polluted soil mixed with eluent in 1: 4 by volume, treatment pond is provided with agitating device, soil is stirred with eluent mix, more than the reaction 4.5h, carry out mud-water separation after the reaction, the waste water that produces is handled by electrochemical reaction, makes heavy metal form precipitate and separate, and the chemical leaching time was controlled in 1 month.
Beneficial effect of the present invention:
The present invention selects to reduce heavy metal in soil total amount and eco-friendly recovery technique, and it is main promptly selecting biology in situ reparation (animal one plant is strengthened compound reparation) for use, and (chemical leaching) handled in materialization is the technology of assisting.In the technology of soil animal restoration of soil polluted by heavy metal, characteristics such as earthworm is big because of its heavy metal accumulation amount, growth cycle weak point, extraction is simple, effect is obvious become the technology that soil remediation has potentiality.In the middle of phytoremediation technology, generally select hyperaccumulative plant for use.The plant extract reparation refers to utilize certain plants that the super accumulation ability of certain heavy metal species is removed heavy metal pollution of soil.Therefore strengthen compound reparation in conjunction with animals and plants, realized biology in situ reparation smoothly, have extremely obvious effects, and do not produce secondary pollution soil to soil.
The specific embodiment
The invention will be further described below in conjunction with embodiment, but protection scope of the present invention is not limited to this.
Embodiment 1
A kind of soil remediation method of handling heavy metal contaminants is pressed the content of beary metal height in the soil, and soil is divided into three classes, i.e. serious pollution soil, intermediate pollution soil and light contamination soil (as table 1), and adopt different technical finesses targetedly.
Sampling mode
But according to evenly and operating principle, be that unit sample ground is cut apart by 10m * 10m with the plot, with each unit sample the collection of layouting, the generality of satisfied detection data.
With 10m * 10m is unit sample ground, selects 5 points each sample, adopts quincunx layouting, and gets four points around the central point of choosing again.(0~20cm) gets 0.5kg, then 5 soil is evenly mixed, and gets pedotheque about 1.0kg at last and puts into brown shuttle and take back to gather top layer at each point respectively with soil sampler.The soil sample that to adopt back then is placed on the plastic sheeting or in the enamel tray and shakeouts, and places room-dry, in air drying process soil block is carried out fragmentation.After sample is air-dry, choose plant and animal residues such as root, stem, leaf, polypide etc. and stone, tuberculosis (lime, iron, manganese).Get a certain amount of grinding by quartering then, deposit in the Brown Glass Brown glass bottles and jars only after sieving with 80 purpose soil samples sieve, put into refrigerator then and preserve.In time carry out record in the sampling process, should comprise soil sample numbering, sampling position and longitude and latitude, soil name, sampling depth, date collected, sampling people etc. in the record.
According to same sample mode, preserve respectively to every sample ground 20~40cm depth bounds sampling, and through after the preliminary treatment.
In order to investigate the contaminated situation of deep soil, according to 5 sample ground of the contaminated degree different choice of soil, adopt in the same way, be the sampling of 40~60cm scope to the degree of depth, and preserve through after the preliminary treatment.
The fetch earth degree of depth and the weight of each point is answered uniformity in the sampling process of layouting, and sampler should bury to the degree of depth of regulation perpendicular to ground.Sampler uses stainless steel, wood, bamboo or plastic ware.Process such as sample treatment, storage can not contacting metal utensil and rubber, with anti-pollution.
Soil samples and detecting
Detect fetching soil sample, pre-treatment and detection method are with reference to " soil environment quality standard " (GB15618-1995) described execution of table 2.
Table 1 classification of soils (according to above-mentioned field sampling Monitoring Data)
(unit: the mg/kg dry ground)
Soil types |
Cd(mg/kg) |
Cu(mg/kg) |
Pb(mg/kg) |
Hg(mg/kg) |
Serious pollution soil |
>3.5 |
>116.0 |
>170.9 |
>0.9 |
Intermediate pollution soil |
1.6~3.5 |
70.4116.0 |
80.1~170.9 |
0.7~0.9 |
Light contamination soil |
<1.6 |
<70.4 |
<80.1 |
<0.7 |
At above-mentioned serious pollution soil, used soil remediation method comprises and carries out chemical leaching earlier, carries out earthworm bioaccumulation reparation and phytoremediation again;
At intermediate pollution soil, used soil remediation method comprises earthworm bioaccumulation reparation and phytoremediation;
At above-mentioned light contamination soil, used soil remediation method is a phytoremediation;
Described earthworm bioaccumulation repair process:
1) with the soil scarifying, apply stalk and dried cow dung class fertilizer and keep soil nutrient, cow dung also can strengthen the effect of phytoremediation.
2) put into vermiculture, put into vermiculture, earthworm ingests by ceaselessly wriggling, and related earth is taken in the body, makes heavy metal stop in vivo and enrichment, water every day during this time, repair process waters water one time every day at least, when temperature is lower than 5 ℃, and mulching straw and film, keep the soil moisture, play interception simultaneously; When temperature is higher than 32 ℃, increase the frequency of watering, guarantee that moisture content is 60~70%; Control soil inner air flow, earthworm wriggles in soil can improve the soil inner air flow.
3) collect vermis, adopt the natural lighting collecting method, 24h waters in advance, and the soil with the upper strata concentrates on cement flooring or the Polypropylence Sheet again, successively push aside, soil is scratched clean, make earthworm concentrate on bottom, reach the collection purpose, and, collect back soil and go back to the shop vermis and soil sieving separating; After three months, depth of soil 20cm is collected with interior one-tenth earthworm, vermis was collected and was once become earthworm in one month summer again, and each first quarter moon was collected and once become earthworm other seasons;
Above-mentioned earthworm is selected big flat No. 2 earthworm earthworm kinds for use, through above-mentioned steps 1), 2), 3) processing cycle of promptly finishing an earthworm bioaccumulation, a processing cycle is 3 months, each processing cycle digs again, carries out four processing cycles altogether;
A processing cycle is added a fertilizer in the above-mentioned earthworm bioaccumulation repair process, and addition is 35kg/m first
2, each thereafter addition is 25kg/m
2
Described chemical leaching is selected to contain the acid solution of chelating agent as eluent, chemical leaching comprises: polluted soil is excavated and move to treatment pond, polluted soil mixed with eluent in 1: 4 by volume, treatment pond is provided with agitating device, soil is stirred with eluent mix, reaction 4.5h, carry out mud-water separation after the reaction, the waste water that produces is handled by electrochemical reaction, makes heavy metal form precipitate and separate, and the chemical leaching time was controlled at 1 month.
Described phytoremediation is selected Indian mustard and two kinds of plants of ramie for use; With three months be a season, autumn and winter plantations Indian mustard, two seasons of spring and summer plantation ramie after per season plantation finishes, connects root and collects, the plantation of digging again, the interpolation fertilizer, finishing the phytoremediation cycle is 18 months.
Embodiment 2
A kind of soil remediation method of handling heavy metal contaminants, press the content of beary metal height in the soil, soil is divided into three classes, be serious pollution soil, intermediate pollution soil and light contamination soil, described soil remediation method at serious pollution soil comprises and carries out chemical leaching earlier, carries out earthworm bioaccumulation reparation and phytoremediation again; Described soil remediation method at intermediate pollution soil comprises earthworm bioaccumulation reparation and phytoremediation; Described soil remediation method at light contamination soil is a phytoremediation;
Described earthworm bioaccumulation repair process:
1), applies stalk and dried cow dung class fertilizer with the soil scarifying;
2) put into vermiculture, put into vermiculture, earthworm ingests by ceaselessly wriggling, and related earth is taken in the body, makes heavy metal stop in vivo and enrichment, water every day during this time, repair process waters water one time every day at least, when temperature is lower than 5 ℃, and mulching straw and film, keep the soil moisture, play interception simultaneously; When temperature is higher than 32 ℃, increase the frequency of watering, guarantee that moisture content is 60~70%; Control soil inner air flow, earthworm wriggles in soil can improve the soil inner air flow.
3) collect vermis, adopt the natural lighting collecting method, 24h waters in advance, and the soil with the upper strata concentrates on cement flooring or the Polypropylence Sheet again, successively push aside, soil is scratched clean, make earthworm concentrate on bottom, reach the collection purpose, and, collect back soil and go back to the shop vermis and soil sieving separating; After three months, depth of soil 20cm is collected with interior one-tenth earthworm, vermis was collected and was once become earthworm in one month summer again, and each first quarter moon was collected and once become earthworm other seasons;
Above-mentioned earthworm is selected big flat No. 2 earthworm earthworm kinds for use, through above-mentioned steps 1), 2), 3) processing cycle of promptly finishing an earthworm bioaccumulation, a processing cycle is 3 months, carries out four processing cycles altogether;
A processing cycle is added a fertilizer in the above-mentioned earthworm bioaccumulation repair process, and addition is 40kg/m first
2, each thereafter addition is 20kg/m
2
Described chemical leaching is selected to contain the acid solution of chelating agent as eluent, chemical leaching comprises: polluted soil is excavated and move to treatment pond, polluted soil mixed with eluent in 1: 4 by volume, treatment pond is provided with agitating device, soil is stirred with eluent mix, more than the reaction 4.5h, carry out mud-water separation after the reaction, the waste water that produces is handled by electrochemical reaction, makes heavy metal form precipitate and separate, and the chemical leaching time was controlled at 1 month.
Described phytoremediation is selected Indian mustard and two kinds of plants of ramie for use; With three months be a season, autumn and winter plantations Indian mustard, two seasons of spring and summer plantation ramie after per season plantation finishes, connects root and collects, the plantation of digging again, the interpolation fertilizer, finishing the phytoremediation cycle is 18 months.
Repairing effect
According to the manageable heavy metal-polluted soil concentration range of above-mentioned three class soil remediation methods, concrete as table 2.
The acceptable soil metal concentration of table 2 recovery technique value
When metal concentration in the soil is lower than in the table the capable value corresponding of A, list light contamination soil scope in, adopt plant to strengthen recovery technique and handle.
When metal concentration in the soil is lower than in the table the capable value corresponding of B, list intermediate pollution soil scope in, adopt the earthworm bioaccumulation technology to dispose.
When metal concentration in the soil is higher than in the table the capable value corresponding of B, list serious pollution soil scope in, adopt the materialization technology to carry out preliminary treatment, utilize the biology in situ recovery technique to dispose again.
Dispose content and repair with materialization drip washing of high pollution soil and earthworm, wherein the high pollution soil drip washing processing time is 1 month (handling back soil backfill continues to repair), and earthworm is repaired can finish 1 processing cycle.
High pollution soil is handled through a drip washing or repeatedly drip washing processing, and heavy metal in soil concentration can reach table 2, and below the capable listed numerical value of B, these concentration are significantly less than the phase I reparation target in the following table 3 simultaneously.Can reach heavy metal concentration value after the listed heavily contaminated soil remediation of table 3 after drip washing is handled, intermediate pollution soil is then handled all after dates through 1 earthworm, and heavy metal in soil concentration is 1 all after date heavy metal concentration numerical value of intermediate pollution soil remediation listed in the table 3.
Table 3 heavy metal in soil concentration (unit: the mg/kg dry weight)
Afterwards, repair seasons (three months is a season), 2 ramies reparation seasons, 2 Indian mustards reparation seasons through 3 earthworm repairing efficiencies (three months is one-period), 2 Indian mustards successively.Above-mentioned as the second stage reparation, second 27 totally months stage, according to earthworm repair and phytoremediation to the heavy metal in soil enriching quantity, each period accessible heavy metal concentration value such as table 4.
Each processing cycle of table 4 second stage is repaired back heavy metal in soil concentration value (unit: the mg/kg dry weight)
The soil remediation treatment effect of above-mentioned enforcement obviously reaches the second stage desired value.According to the foregoing description, final treatment effect is summarized as:
Before the processing:
Plot soil pollution situation (0-20cm) is repaired in table 5 demonstration
Main polluted heavy metals |
Cd |
Cu |
Pb |
Hg |
Minimum of a value |
2.0 |
99 |
85 |
0.6 |
Maximum |
11.5 |
229 |
568 |
1.3 |
Handle the back:
Soil remediation quality after table 6 is handled
Main polluted heavy metals |
Cd |
Cu |
Pb |
Hg |
Repair back (maximum) |
<0.3 |
<50 |
<50 |
<0.3 |