Background technology
Soil and underground water are not only important agricultural production resource, also are important environmental key-elements, are the bases that the mankind depend on for existence.Tellurian soil is various artificial and the bodies that compile natural pollutant, and most pollutant finally can be trapped in the soil in the environment, thereby causes soil environment to go from bad to worse.Along with the fast development of petroleum industry and chemical engineering industry, organic substance is more and more serious to the pollution of soil, and has surpassed heavy metal pollution and radioactive pollution and leap to the first, and has formed the contaminated site of One's name is legion.The investigation of contaminated site and repair the environment difficult problem that become international, and more and more cause people's attention.Organic pollution in the soil of place is mainly derived from: (1) is in the exploration and exploitation, storage and transportation of oil, because the oil discharging that misoperation or accident leakage cause or excessive; (2) ground such as oil, Chemical Manufacture district, gas station form lands the seepage of oil, the discharging of oil-containing production waste and oil pipeline; (3) chemicals production such as chemical plant, insecticide factory enterprise, raw material that causes in transit at workshop, packing workshop, medicine warehousing storage and on-site and medicine are revealed, and the raw material and the waste water of industry dischargings such as printing, building materials, spraying.If above-mentioned contaminated site is not in time administered, then can cause serious underground water pollution, difficulty of governance and expense in the future will be multiplied.
At present, contaminated site recovery technique commonly used comprises dystopy and original position two big classes.Dystopy mainly is meant to be excavated and post processing, promptly through means such as machinery, manual works, makes soil leave original position, adopts several different methods such as Chemical Physics or biology to its post processing, disposal and utilization more again.The dystopy recovery technique relates to cuts the earth and transhipment, has the danger of secondary pollution in the process, exists obviously not enough.Based technique for in-situ remediation is being used widely in recent years.Wherein, the U.S. has dropped into substantial contribution and has been used for soil remediation since the mid-80, and some new based technique for in-situ remediation arise at the historic moment, as chemical oxidation, SOIL GAS carry, microorganism is repaired etc.Wherein, it is the most economical effective method of removing organic pollution in the aeration zone soil that SOIL GAS is carried (SVE), is called " revolutionary technology " by EPA (EPA) and vigorously advocates application.
The SVE technology is a kind of physical method that utilizes, and through reducing the vapour pressure in soil aperture, is converted into vapor form to the pollutant in the soil and the technology removed, can be divided into that original position soil gas is put forward technology, the dystopy SOIL GAS is carried technological and heterogeneous microwave leaching technology.Gas is carried the aeration zone that technology is applicable to that underground reservoir is above; Heterogeneous microwave leaching technology is applicable to aeration zone and underground reservoir.Original position soil gas is put forward technology and is applicable to the volatile organic pollution of processing, like organic halides or non-halides, also can be used for removing the pollutants such as oils, heavy metal, polycyclic aromatic hydrocarbon or bioxin in the soil; The dystopy SOIL GAS is put forward technology and is applicable to the contaminated soil of repairing organic halogen and non-halides; Heterogeneous microwave leaching technology is applicable in the processing, the organic pollution in the hyposmosis type stratum.
The distinguishing feature of SVE technology be workable, as to handle pollutant wide ranges, design relatively simple (can operate) by standard device, do not destroy soil texture, cost is lower and potential value etc. is arranged recycling refuse.SVE will reach the best efficient of system and the removal effect of pollutant because of not needing complicated design or special devices, thereby is superior to other like technology such as biological treatment or soil flushings.The SVE The Application of Technology has its precondition and the scope of application, need carry out necessary investigation and assessment to contaminated site, grasps its edaphic condition and pollution situation.The influence factor of SVE repairing effect has vapour pressure and the environment temperature etc. of structure and layering, gas phase extracting flow, the pollutant of permeability, soil moisture content and groundwater depth, the soil of soil.
The SVE technology is because it has effective removal VOCs and advantages such as easy operating and operation in the environment remediation field.Be widely used in the actual engineering in soil and underground water reparation field by developed country at present.For improving the operational effect of SVE technology; Can spray (Air Sparging like air with other; AS), the two-phase extracting (Dual-phase Extraction, DPE), directly creep into (Directional Drilling, DD), wind-force and fracturing (Pneumatic and Hydraulic Fracturing; PHF) and heat strengthen that (Thermal Enhancement TE) waits based technique for in-situ remediation to combine and forms the SVE enhancement techniques.Hot reinforcement technique, i.e. soil original position heating is meant through direct or indirect heat exchange, and pollution medium and contained organic pollution thereof are heated to enough temperature, makes organic pollution from pollution medium volatilization or separating process.Hot reinforcement technique comprises heating using microwave, radio frequency heating, resistance heated, hot-air injection, high-temperature steam injection etc., can obviously reduce the clarification time, also can remove low volatile organic or semi-volatile organic matter (sVOC) that conventional SVE technology can not be removed.Wherein, high-temperature steam in being usually used in actual engineering, has shortened the reparation duration with its characteristics that source is wide, cheap, heat content is high greatly.Similar with the SVE technology, the factor that influences the Steam Heating reinforcement technique is numerous, like soil permeability, soil layer construction, injection pressure, vapor (steam) temperature and flow etc.
At present, there have been unit or individual to carry out the research of some relevant organic contamination place recovery techniques.Patent CN1290632C discloses a kind of volatility and the half volatile organic polluted soil is administered technology and device outside the venue; Through from the place, excavating and insert soil in one container; The pollutant volatilization that utilizes electrical heating and vacuum extraction to impel to be adsorbed in the soil; Take away with gas phase, finally realize the target of soil remediation.But this arts demand excavates dystopy with soil and handles, and will cause secondary pollution in the process, and the power consumption of electrical heating simultaneously is huge, and cost is higher.Patent CN1185055C discloses a kind of pollution soil steam treatment method and device; This method utilizes slush pump to pump slurry into high-pressure reactor through contaminated soil is configured to mud in a container, and electrical heating is to 200-300 ℃; Make polycyclic aromatic hydrocarbon pollutant desorption from soil; Get into steam, the soil after the purification is discharged by separator separates; Polyaromatic hydrocarbon pollutant and water vapor condensation separate discharge through the liquid liquid/gas separator, finally realize the reparation of contaminated soil.The shortcoming of this method is that soil is configured to the water that mud needs labor, and the mud time power consumption in the heating high-pressure reactor is huge, and lot of energy is used to heat moisture, causes energy waste.
Problem to present some soil remediation technology face is strengthened the technological influence factor of SVE with defective and steam heat; The present invention has designed one and has overlapped the process route that comprises steam injected system, soil extraction system, monitoring system and ground waste gas Waste Water Treatment, and this cover technology can be used for the field repair in organic contamination place.
Summary of the invention
The object of the present invention is to provide a kind of simple, quick, feasible organic contamination place restorative procedure, promptly adopt steam injected system, soil extraction system, monitoring system and ground waste gas Waste Water Treatment associated working to carry out the method that original position soil is repaired.
The present invention realizes through following technical scheme: a kind of based technique for in-situ remediation of organic polluted soil is characterized in that this method comprises four systems: 1. steam injected system, 2. soil extraction system, 3. monitoring system, 4. ground waste gas Waste Water Treatment.The steam injected system is to inject well construction by steam generator, flow control valve, jet chimney, pressure-regulating valve and steam, and there is flow control valve in the steam generator exit, and steam injects the well well head and is provided with pressure-regulating valve; The soil extraction system is carried flowmeter, vacuum blower and extraction line by extraction well, heat exchanger, gas-liquid separator, gas and is formed, and the extraction well well head is provided with vacuum meter and gas sample tap, and valve is set on the main line; Monitoring system is made up of monitor well, pressure tester, temperature measuring equipment; Ground waste gas Waste Water Treatment is made up of activated carbon adsorber or high-temperature catalytic oxidation furnace, waste water storage tank, water pump and active carbon filtering device.
The based technique for in-situ remediation of described a kind of organic polluted soil is according to contaminated site soil layer characteristic and pollutant distribution situation, sets up soil repair system, confirms that steam injects position, the degree of depth and the structure of well, extraction well and monitor well.
The based technique for in-situ remediation of described a kind of organic polluted soil, its repair process can be continuously or intermittently carried out, and contaminated site keeps the face of land to seal in repair process, and encapsulant is a kind of in cement concrete, pitch, bentonite pad, the density polyethylene film with high.
The well casing end that described steam injects in well, extraction well and the monitor well is sealed by plug, and well casing is provided with the well screen, and the well screen is arranged in the soil aeration zone.Steam injects well and is connected in parallel through the main steam header road, and extraction well is connected in parallel through the extracting trunk line, and every mouthful of well well head is provided with controlled valve, can work simultaneously by all wells, also can optionally get well work.
Described steam injects has well casing to connect the ground upper pipeline in well, extraction well and the monitor well; Packing matcrial between the well casing and the borehole wall is in case locking system is short-circuited with the ground external environment, and encapsulant is cement concrete, bentonite or clay, gravel from top to bottom successively.
The based technique for in-situ remediation of described a kind of organic polluted soil; Operating characteristic is following: contaminated site soil and organic pollution to uniform temperature, are impelled organic pollution from contaminated soil, to evaporate by Steam Heating, get into extraction line in company with steam via extraction well; Cool off through heat exchanger; Get into gas-liquid separator and realize gas-liquid separation, condensate liquid flows into the waste liquid storage tank by the waste liquid pipeline, and waste gas gets into activated carbon adsorber or high-temperature catalytic oxidation furnace through blower fan; Remove pollutant, realize qualified discharge.
The based technique for in-situ remediation of described a kind of organic polluted soil, monitor well are used for monitoring the soil heating-up temperature of contaminated site, underground vacuum and groundwater level.
The based technique for in-situ remediation of described a kind of organic polluted soil, its process route is described below: (1) gas is put forward the system process parameter and is confirmed.At first, at contaminated site one breath is set and carries well, and around gas is carried well, the monitor well of some is set; Then, select suitable vacuum air pump, adopt empty survey method to measure the characteristic curve of air pump, confirm that gas puies forward the working flow scope; Then, connect vacuum air pump and extraction well, the open vacuum air pump, test well head vacuum and gas are put forward the relation of flow, obtain SVE system curve; At last, measure the vacuum of each monitor well under a certain extracting flow, confirm the radius of influence of individual well extracting.(2) steam injected system technological parameter confirms.Suitable distance is provided with a bite steam injection well carrying well from gas, and at its arranged around monitor well; The saturated vapor of certain pressure intensity (2-8atm) is transported to steam through steam pipework and injects the well well head, under the regulating action of wellhead pressure control valve, is adjusted to suitable pressure, injects steam and injects well; Under the extraction well condition of work,, confirm that suitable steam injects the effective radius of well through the monitor well monitoring soil moisture and the relation of heat time heating time.(3) waste gas Waste Water Treatment disposal ability is confirmed on the ground.
The invention provides a kind of organic contamination place recovery technique rapidly and efficiently, compare other restorative procedure, this method just can reach the management goal of expection with relative small device investment.Engineering construction is the result show, the organic contamination place in-situ remediation method that the present invention is that a kind of reasonable in design, equipment is simple, the operation operation is convenient and is easy to safeguard has broad application prospects.
Description of drawings-
Fig. 1 is a repair system work sketch map.
Be the explanation of main part mark in the Figure of description below:
1-emission-control equipment 2-vacuum blower 3-gas flowmeter 4-gas-liquid separator
5-heat exchanger 6-extraction line 7-valve 8-vacuum meter 9-cement concrete
10-bentonite 11-gravel 12-extraction well 13-well casing plug 14-well screen
15-casing 16-pressure gauge 17-temperature measuring gauge 18-vapour source 19-welded still pipe
20-pressure-regulating valve 21-Pressure gauge 22-steam injects well 23-centrifugal water pump
The 24-wastewater treatment equipment
The detailed example of practical implementation
This technical method is applicable to the place soil that reparation is polluted by volatility or semi-volatile organic matter, as by contaminated soils such as benzene series thing, chlorinated hydrocarbon, gasoline, TVOC.Before recovery project begins, must confirm the crucial operational factor of each system.
Gas is put forward the system core operational factor: for guaranteeing the repairing effect in place, must investigate the extracting ability of extraction system earlier, confirm the extracting capacity data of extraction system vacuum blower.The characteristic curve of blower fan adopts empty survey method to measure; The inlet and the extracting main line of vacuum blower are broken off; The U-shaped pressure gauge is adopted in the measurement of PIP, records the relation of Pump Suction Nozzle vacuum and gas phase suction flow, draws the characteristic curve of vacuum blower.Vacuum blower is linked to each other with the extracting main line, and the air-tightness of check system is tested the gas flow under the different extracting vacuum degree condition, describes the SVE working curve, and the characteristic intersection point of this curve and vacuum blower is the operating point.Under the condition of operating point, open the SVE extraction system, the well head vacuum of each monitor well around the record extraction well, thereby the pressure influence radius of tentatively definite extraction well, the pressure influence radius is one of most important parameters of SVE engineering design.Measure under certain gas phase extracting flow variation, to investigate the variation of repairing instantaneous vacuum under anisotropic influence of place soil and the unstable state and the relation of radial distance apart from the instantaneous vacuum of monitor well well head of extraction well different radial distances.Measure the variation of the instantaneous vacuum of monitor well different depth under certain gas phase extracting flow, to investigate the permeability situation of repairing each layer soil in the soil vertical depth of place.
The crucial operational factor of vapour system: under the situation of extraction well work; Inject well to steam and feed saturated vapor; Utilize soil and pollutant in the heat place that the steam condensation discharges; Impel organic pollution from pollution medium, to volatilize or separate, through extraction line extracting to exhaust treatment system on the ground.In the process that feeds steam; Inject the wellhead pressure control valve of well through steam regulation; Monitor different steam and inject the influence of pressing the place earth formation; Heating rate through monitor well monitoring soil and concern over time apart from the soil moisture that steam injects Jing Butongjingxiangjulichu is confirmed finally that suitable steam injects to press and steam injects the effective radius of influence of well individual well.
Below in conjunction with actual engineering present technique is carried out detailed explanation.A certain small chemical factory place is polluted by multiple organic pollution, and pollution condition is listed in table 1.
Table 1 contaminated site situation list
The about 400m of contaminated site area2, the contaminated soil layer construction in place mainly is plain fill and silt folder silty clay from top to bottom, the gentle vertical infiltration coefficient about 10 of the soil water-4Cm/s pollutes the about 3.6m of the degree of depth, is a compound contaminated site.Pollute in the repair process, at first build the thick cement concrete of one deck 50mm, seal place to be repaired on the contaminated site face of land; Then carry out on-the-spot pilot plant test, confirmed effective radius of influence of extraction well and steam well; After key parameter was confirmed, in contaminated site, beating diameter was 9 mouthfuls of steam injection wells of 130mm, and 16 implications are carried well, and 20 mouthfuls of monitor wells, steam inject between the well and the well spacing between the extraction well is 6m, according to the casing of each well of installation shown in Figure 1; Connect extraction line and steam pipework then respectively, extraction system adopts two vacuum blower series connection, a job, and one is subsequent use, and steam is provided by a steam boiler; Waste water and gas adopts charcoal absorption to handle.In the repair process, the extracting flow of regulating vacuum blower is at 20m3About/min, 16 mouthfuls of extraction wells are divided into four unit, and each unit is by 4 mouthfuls of extraction well parallel connections, and extraction procedure is the sequence of unit operation, each unit extracting 45 minutes.All steam inject well and move simultaneously at repair process, utilize wellhead pressure control valve steam regulation to inject and are pressed in about 0.6atm.The recovery project in this place is moved about 5 months, about 3 months of extracting time remaining, during keep steam to inject, keep the soil moisture about 80 ℃.After the place was repaired and finished, each pollutant load all was lower than the screening value.
The detailed example of said enforcement just is used for explanation rather than restriction the present invention, and the other forms of accommodation of having done under the situation in the present invention enlightens down and do not break away from the scope that claim of the present invention protects is all within protection of the present invention.