A kind of restorative procedure of contaminated soil
Technical field
The invention belongs to technical field of environmental management, and in particular to a kind of restorative procedure of contaminated soil, especially suitable for
The soil of serious pollution in heavy metal small area.
Background technique
The situation is tense for China's heavy metal pollution of soil, shows that arable land heavy metal pollution is serious, and industrial and mining area and its surrounding are dirty
The features such as dye aggravation and high background value regional soil heavy metals exceeding standard.Number of ways causes the hair of heavy metal pollution of soil phenomenon
It is raw, for example, exploitation, the smelting of heavy metal, sewage irrigation, the application and special geochemistry of fertilizer containing heavy metal, pesticide
Circulation etc..Heavy metal has notable features, the soil such as toxicity is big, incubation period is long and can be bioaccumulation once heavy metal-polluted
Dye certainly will be amplified by the accumulation of food chain and seriously affect human health.Meanwhile heavy metal pollution of soil can also be by it certainly
The Transport And Transformation of body directly contributes the pollution of water environment and air environment.
The restorative procedure of heavy metal-polluted soil is numerous, but from fundamental way there are two types of classification only, first is that by heavy metal-polluted soil
Immobilization or Passivation Treatment on the spot make it be changed into invalid state from available state, so that reducing heavy metal enters food chain and periphery
The risk of environment.Second is that heavy metal is removed from soil, thoroughly reduces soil using the methods of chemical extraction or bio-absorbable
The total amount of heavy metal.Previous approach does not reduce heavy metal-polluted soil total amount, condition be suitable in the case where, heavy metal-polluted soil have by
The possibility reactivated.And heavy metal because out of soil, fundamentally being solved the problems, such as heavy metal pollution of soil by latter approach.
Chemical leaching method is exactly a kind of effective method for reducing heavy metal-polluted soil total amount.It makes weight using different digestion agents
Metal moves to liquid phase from solid phase of soil, and achievees the purpose that reduce heavy metal-polluted soil by the discharge of leachate.Soil leaching
The small area soil remediation for proposing technology serious pollution suitable for heavy metal, can achieve it is efficient to heavy metal-polluted soil, quickly go
The purpose removed.Nevertheless, soil extract goes removing heavy metals to still have shortcoming at present, for example, soil extract was implemented
Journey soil needs to move away from original position, soil extract contain a large amount of heavy metal needs be further processed and soil extract after soil
The nutritional ingredients such as nitrogen, phosphorus and potassium can be lost.Above-mentioned deficiency will increase soil remediation cost and cause subsequent soil agricultural
The problem of nutrient deficiency.
Summary of the invention
In view of the deficiencies of the prior art, the present invention provides a kind of restorative procedure of contaminated soil, extracts soil by situ
In heavy metal, absorb the heavy metal in enrichment leaching liquor with water plant, the post-processing for solving soil extract leachates asks
The problem of nutritional ingredients such as Soil Nitrogen, phosphorus and potassium can be lost after topic and soil extract.It is mentioned for the reparation of heavy-metal contaminated soil
One has been supplied to open one's minds and approach.
The technical solution adopted by the present invention to solve the technical problems is:
A kind of restorative procedure of contaminated soil, step include:
A, contaminated soil is dug out and in the heatable adobe sleeping platform that is backfilling into after Anti-seeping technology;
B, digestion agent and water are made into extracting solution to be added in contaminated soil, make soil pH between 5-6.5, and make molten
Liquid is higher by soil surface 5-25cm, extracts Heavy Metals in Contaminated Soils;
C, by wetland plant plant in contaminated soil, and contaminated soil is made to be in water logging state, is harvested after 1 Growing season
The plant of enriching heavy metal.
Anti-seeping technology step in the step A are as follows: the barrier film on contaminated soil surrounding ground pad, the pollution that will be dug out
Soil is stacked on barrier film;The heatable adobe sleeping platform surrounding formed after digging out soil and bottom spread can natural degradation plastic film,
The soil dug out is filled in heatable adobe sleeping platform again afterwards, and around heatable adobe sleeping platform build 0.5-1.0m high enclosure wall, can natural degradation plastics it is thin
Film extends at the top of wall;
Digestion agent is organic acid and/or hydrochloric acid in the step B;The digestion agent is to analyze pure, the extracting solution prepared
PH is 4-6;The organic acid is selected from one or more of citric acid, malic acid, acetic acid, tartaric acid;The extraction Polluted Soil
The extraction time of heavy metal is 48-72h in earth, maintains soil liquid pH 5-6.5 constant during extraction;
Wetland plant is iris or water hyacinth in affiliated step C;Iris is yellow flag.
The beneficial effects of the present invention are:
The present invention develops a kind of soil extract connection for the deficiency of current chemical leaching method processing heavy-metal contaminated soil
The method for closing wetland plant in-situ immobilization heavy metal-polluted soil is easy to engineering construction, environmental-friendly, while having following excellent
Gesture:
1) it is handled using biodegradable films bed course, ensures soil in-situ extraction, saved soil landed cost.
2) leaching of soil containing heavy metal is solved using wetland plant synchronization process soil extract in soil extract process
The problem of liquid post-processes out, while improving efficiency.
3) using saliferous organic acid or hydrochloric acid do not avoid inhibition of the leachate itself to plant growth as digestion agent.
4) this method plant soil restoration period is shorter, has at low cost, without secondary pollution, and plant is able to maintain water
Soil increases soil fertility, and then accelerates the advantage of ecosystem self-regeneration, while reaching to soil weight by the harvest of plant
The purpose that metal is thoroughly repaired.
Specific embodiment
Carry out further instruction combined with specific embodiments below.
Embodiment 1
The present invention is carried out for the soil that area is smaller, heavy metal pollution is more serious, first takes measures to utilize digestion agent
Extraction in situ, it is rear to transplant wetland plant repairing heavy metal in soil.The implementation steps of the invention are as follows: step 1: first in contaminated soil
Barrier film on surrounding ground pad, then according to heavy metal pollution depth and after repairing, the purposes of soil digs out contaminated soil,
It digs out soil to be stacked on barrier film, prevents the pollution to Soil Surrounding.Step 2: the heatable adobe sleeping platform four formed after digging out soil
Thermoplastic starch plastic film is spread in week and bottom, after the soil dug out is filled in heatable adobe sleeping platform again, and four at the top of heatable adobe sleeping platform
Surrounding builds 0.5m high enclosure wall, and biodegradable plastic film extends at the top of wall to make antiseepage.Step 3: selecting lemon acidleach
It proposes agent and water is made into the solution that pH is 4.5, solution is poured in the heatable adobe sleeping platform of landfill contaminated soil, make to extract soil pH in 5-
Between 5.5, and solution is made to be higher by soil surface 10cm.Step 4: keeping soil extract process 48h, the soil liquid is during which maintained
PH 5-5.5 is constant.Step 5: select acidproof and energy enriching heavy metal wetland plant yellow flag plant in extraction soil, the phase
Between waterlogging state kept by addition heavy metal free polluted river water, pond water or tap water.Step 6: after 1 Growing season
Plant is harvested, heatable adobe sleeping platform surrounding leakage proof wall is removed.
Contaminated soil after detection processing, heavy metal ions in soil Cr, Pb, Cu, Cd concentration by 5.67mg/Kg,
21.72mg/Kg, 11.43mg/Kg, 7.56mg/Kg are reduced to 0.51mg/Kg, 0.33mg/Kg, 1.12mg/Kg, 0.23mg/ respectively
Kg。
Embodiment 2
The present invention is carried out for the soil that area is smaller, heavy metal pollution is more serious, first takes measures to utilize digestion agent
Extraction in situ, it is rear to transplant wetland plant repairing heavy metal in soil.The implementation steps of the invention are as follows: step 1: first in contaminated soil
Barrier film on surrounding ground pad, then according to heavy metal pollution depth and after repairing, the purposes of soil digs out contaminated soil,
It digs out soil to be stacked on barrier film, prevents the pollution to Soil Surrounding.Step 2: the heatable adobe sleeping platform four formed after digging out soil
Thermoplastic starch plastic film is spread in week and bottom, after the soil dug out is filled in heatable adobe sleeping platform again, and four at the top of heatable adobe sleeping platform
Surrounding builds 0.5m high enclosure wall, and biodegradable plastic film extends at the top of wall to make antiseepage.Step 3: selection malic acid,
Acetic acid, tartaric acid, HCl extract agent and water wiring solution-forming, malic acid, acetic acid, tartaric acid, hydrochloric acid solution pH value are 5-6;It will
Solution is poured in the heatable adobe sleeping platform of landfill contaminated soil, makes to extract soil pH between 6-6.5, and solution is made to be higher by soil surface
10cm.Step 4: keeping soil extract process 60h, during which maintain soil liquid pH 6-6.5 constant.Step 5: selecting acidproof
And can enriching heavy metal wetland plant water hyacinth plant in extraction soil in, during which by addition heavy metal free polluted river water,
Pond water or tap water keep waterlogging state.Step 6: harvesting plant after 1 Growing season, heatable adobe sleeping platform surrounding cut-pff wall is removed
Body.
Contaminated soil after detection processing, heavy metal ions in soil Cr, Pb, Cu, Cd concentration by 5.67mg/Kg,
21.72mg/Kg, 11.43mg/Kg, 7.56mg/Kg are reduced to 0.57mg/Kg, 0.46mg/Kg, 1.32mg/Kg, 0.34mg/ respectively
Kg。