CN103523889A - PRB joint control-based hydraulic power capturing method for removing contaminants in underground water - Google Patents

Abstract

The invention relates to the technical field of removing contaminants in underground water. To improve water quality by hydraulic power capturing technology and obtain good effects, the technical scheme adopted by the invention is a PRB joint control-based hydraulic power capturing method for removing the contaminants in the underground water. The method comprises steps of: 1) determining the position and the scale of a pollution source, and determining the main contaminants in the underground water; 2) collecting hydrogeological data of an research area, and determining hydrogeological parameters including the permeability coefficient, the specific yield and the infiltration supplement coefficient of the research area; 3) determining the main parameters comprising the scale and the form of a hydraulic power capturing zone, pumping load of capturing wells, the number of the capturing wells, the distance among the capturing wells, the maximum capturing width, and stationary points according to hydrogeological conditions of the site; and 4) determining the effective distance between the hydraulic power capturing zone and the PRB according to the form and size of a contamination plume, thus ensuring effective joint control to remove the contaminants in the underground water. The method is mainly used for removing the contaminants in the underground water.

Description

Hydraulic capture method based on PRB joint control removal groundwater pollutant

Technical field

The present invention relates to a kind of method of removing underground water pollutant, is to process the hydraulic capture technique of underground water pollutant with PRB joint control specifically.

Technical background

Groundwater resource occupy very important status in China's water resources, because it distributes extensively, water quality is good, the ability of regulating and storing strong, water supply assurance degree is high, are just developed more and more widely.Yet, along with socioeconomic development, the trade effluent refuses of a large amount of discharges, agricultural pollutant, intensive livestock and poultry cultivation and the excessive use of nitrogenous fertilizer are, the unscrupulous discharge of domestic waste, and the unordered exploitation of underground water, and underground water is polluted gradually.The groundwater pollution of China presented by point to face develop, by east to western part expansion, by city to rural area, spread, trend by from part to regional diffusion; Contaminant component by inorganic to organic development, hazard rating is on the rise; Groundwater pollution area constantly expands, and pollution level constantly increases the weight of.

Groundwater pollution is the Tough questions that China faces, and controlling and repair groundwater pollution is one of important process of protection China water resources.

Continuous reinforcement along with environmental protection consciousness in world wide; the scope of groundwater pollution continues to increase, degree is constantly deepened; national governments promulgate that a large amount of rules come priority protection and purifying aqueous layer in succession, and Chinese scholars has also extensively carried out that groundwater pollution is controlled and the research of recovery technique.Modal two kinds of underground water recovery techniques are permeable reactive barrier (Permeable Reactive Barrier is called for short PRB) and hydraulic capture technique.Hydraulic capture technique is the water injection well of taking out by a series of reasonable Arrangement, extracts to greatest extent polluted underground water, effectively controls a kind of water power technology of Contaminants Transport.Its core is hydrogeological background condition, pollutent character and the distribution characteristics thereof according to contaminated site, and the subject knowledges such as application seepage theory and Optimum Theory arrange improvement well and form hydraulic capture band in downstream, pollution zone.From the eighties in 20th century, start successively the report of this respect abroad, over especially past 10 years, research is carried out more extensively.Investigator's discovery, during with the contaminated waterbearing stratum of hydraulic capture technical finesse, key issue is the underground water that a kind of effective interception system intercepting of design is polluted, and does not allow Contaminants Transport to go to downstream.At present, hydraulic capture technique has been widely used in arranging of the design of Pump-and-Treat system and water conservation district abroad.PRB is generally arranged on underground storage layer, perpendicular to direction of groundwater flow, along with polluted underground water this reaction medium of flowing through, by mechanism such as absorption, precipitation, redox, biological degradations, Pollutant levels is reduced.Compare with traditional extraction facture, PRB technology is low without additionaling power, working cost, is the Remedy Technology of Contaminated Groundwater of a worth research and extension, has carried out a large amount of engineerings and experimental study at present America and Europe, and commercial applications, the domestic conceptual phase that is still in have been started.PRB technology is as the based technique for in-situ remediation of polluted underground water, its major advantage is to take out and Ground Processing System without pump, and reflection dielectric dissipation is very slow, there is the reach several years processing power of decades even, the daily long term monitoring that only needs, needs working cost hardly, can permanently effectively move, influence ecological environment not, so PRB is a kind of up-and-coming pollution treatment technology.At American-European PRB, successfully applied to the reparation of carrying out polluted underground water on the spot.China aspect PRB research also in preliminary experiment chamber conceptual phase.

Summary of the invention

For overcoming the deficiencies in the prior art, the present invention is intended to improve water quality by hydraulic capture technique, and obtains good result.For achieving the above object, the technical solution used in the present invention is that the hydraulic capture method based on PRB joint control removal groundwater pollutant, comprises the steps:

1) determine position, the scale of source of pollution, define the principal pollutant in underground water; Find out the distribution characteristics of distributional pattern, scope and the Pollutant levels of pollution of underground aquifers plumage;

2) collection research district hydrogeologic data, determines study area hydrogeological parameter, comprises permeability coefficient, specific yield, infiltrates supply coefficient;

3), according to place hydrogeological conditions, determine and comprise scale, form, intercepting and capturing well pump-out, the quantity of intercepting and capturing well and the spacing of hydraulic capture band, the maximum significant parameter of intercepting and capturing width and stationary point;

4) according to the form of Pollution Plume, size, determine effective spacing of intercepting and capturing band and PRB, guarantee effective joint control and remove underground water pollutant.

The definite of capture region width is specially:

The width 2y of capture region _lwith pumped well flow there is the relation shown in following formula in Q:

$2y_L=\±\frac{Q}{\mathrm{KBi}}$ Formula (1)

Wherein, Q-pump-out, m ³/ d; K-permeability coefficient, m/d; B-waterbearing stratum thickness, m; I-hydraulic gradient;

(2) stationary point determines

Distance x between stationary point and pumped well _lwidth 2y with pumped well flow Q, capture region _lthere is following relation:

$x_L=-\frac{Q}{2\mathrm{\πKBi}}=\frac{y_L}{2\mathrm{\π}}$ Formula (2)

(3) hold range boundary water mechanical equation determines

Direction of groundwater flow is parallel with X-axis, but flows to X-axis negative direction, and pumped well is arranged in Y-axis, and calculating hold range boundary water mechanical equation can be written as:

$Y=\±\frac{Q}{2\mathrm{BV}}-\frac{Q}{2\mathrm{\πBV}}\mathrm{ta}{n}^{-1}\frac{Y}{X}$ Formula (3)

In formula, V is local ground watering seepage velocity, m/d.Other symbol cotypes (1).

For Duo Koujing, the result superposition of every a bite well gained is got up, obtain its numerical solution; For Duo Koujing, all hydraulic capture pumped wells should be on y axle aligning and distributing with origin symmetry, when n is odd number, a glance well in bosom should be arranged on initial point, its well spacing D can calculate by (4) formula.

$D=\frac{1.2Q}{\mathrm{BV}}$ Formula (4).

The present invention possesses following technique effect:

Make full use of the advantage of hydraulic capture technique and permeable reactive wall (PRB) technology, for solving, underground water repair process length consuming time, removal efficiency are low, the complicated unmanageable problem of pollutant kind.

Accompanying drawing explanation

The hydraulic capture technique floor map of Fig. 1 based on PRB joint control.

The hydraulic capture technique constructed profile of Fig. 2 based on PRB joint control.

Embodiment

The object of the present invention is to provide a kind of hydraulic capture technique based on PRB joint control removal groundwater pollutant.Its step comprises:

1. determine position, the scale of source of pollution, define the principal pollutant in underground water; Find out the distribution characteristics of distributional pattern, scope and the Pollutant levels of pollution of underground aquifers plumage.

2. collection research district hydrogeologic data, determines study area hydrogeological parameter, as permeability coefficient, specific yield, the supply coefficient etc. that infiltrates.

3. according to place hydrogeological conditions, determine scale, form, intercepting and capturing well pump-out, the quantity of intercepting and capturing well and the spacing of hydraulic capture band, the maximum significant parameters such as width and stationary point of intercepting and capturing.Parameter determination method is as follows:

(1) capture region width determines

Under the effect of the flow Q that draws water, in waterbearing stratum, the watershed line of a underground water will be there is, by underground moisture, be two regions, underground water beyond watershed line will flow to the downstream area in waterbearing stratum, watershed line can be extracted out by pumped well with interior underground water, no longer flow to the capture region that ，Cheng Ci region, downstream is this pumped well, the maximum width of this capture region is made as 2y _l.

The width 2y of capture region _lwith pumped well flow there is the relation shown in following formula in Q:

$2y_L=\±\frac{Q}{\mathrm{KBi}}$ Formula (1)

Wherein, Q-pump-out, m ³/ d; K-permeability coefficient, m/d; B-waterbearing stratum thickness, m; I-hydraulic gradient

(2) stationary point determines

On the axis at pumped well place, the watershed line of underground water and axes intersect are in an x=-x _l, the underground water of trip will be extracted out by pumped well at that point, and the underground water in this downstream will flow to the downstream area in underground water flow field.As stagnation point, some x=-x _lthe groundwater velocity at place is zero, claims this point for stationary point.Distance x between stationary point and pumped well _lwidth 2y with pumped well flow Q, capture region _lthere is following relation:

$x_L=-\frac{Q}{2\mathrm{\πKBi}}=\frac{y_L}{2\mathrm{\π}}$ Formula (2)

(3) hold range boundary water mechanical equation determines

The derivation of hold range boundary water mechanical equation analytic model need meet following hypothesis: waterbearing stratum is homogeneous isotropy, unlimited spread in the horizontal direction; Uniform-flow; Vertical hydraulic gradient can be ignored; Pumped well is fully penetrating well, and pump-out is constant.Direction of groundwater flow is parallel with X-axis, but flows to X-axis negative direction, and pumped well is arranged in Y-axis.Can calculate under these conditions hold range boundary water mechanical equation can be written as:

$Y=\±\frac{Q}{2\mathrm{BV}}-\frac{Q}{2\mathrm{\πBV}}\mathrm{ta}{n}^{-1}\frac{Y}{X}$ Formula (3)

In formula, V is local ground watering seepage velocity, m/d.Other symbol cotypes (1).

More than a bite well derived and calculated, for Duo Koujing, above-mentioned method of calculation also can be got up the result superposition of gained for every a bite well, can obtain its numerical solution.For Duo Koujing, all hydraulic capture pumped wells should be on y axle aligning and distributing with origin symmetry, when n is odd number, a glance well in bosom should be arranged on initial point, its well spacing D can calculate by (4) formula.

$D=\frac{1.2Q}{\mathrm{BV}}$ Formula (4)

4. according to the form of Pollution Plume, size, determine effective spacing of intercepting and capturing band and PRB, guarantee effective joint control and remove underground water pollutant.

In this hydraulic capture system, in order to prevent that polluted underground water from spreading downstream, need, by arranging pumped well, to form the capture region of certain width, this capture region should cover Contaminant plumes band.Therefore, the width of capture region should be more than or equal to existing Contaminant plumes bandwidth, and hydraulic capture maximum width is more than or equal to the length of PRB simultaneously.Determine effective spacing of intercepting and capturing band and PRB, namely stationary point is more than or equal to the length of 2 times of PRB to the spacing of PRB, can effectively avoid the interference of hydraulic capture near flow field PRB, is convenient to PRB and effectively moves.

In conjunction with hydraulic capture technique scheme of the present invention, provide following examples:

Utilize this invention to carry out hydraulic capture engineering to the somewhere hexavalent chromium polluted plumage of flyash field underground water.

1. flyash field basic condition

Certain flyash field is a level land Hui Chang, and floor space 43.9 ten thousand m2, are rectangle, and thing is about 780m, the wide about 510m in north and south.Ash is positioned at certain alluvial-proluvial fan runoff zones, and groundwater type is loose rock class pore water, and waterbearing stratum is comprised of clay ovum gravel and the clay gravel of single structure, thickness 35-40m.Underground water is diving, and runoff is unimpeded, and watery is stronger, and single hole aquifer yield is greater than 1000m3/d, permeability coefficient 10--30m/d.According to flyash place and near Ground water Quality Survey thereof, in underground water, the region of pollution of chromium is centered by flyash field, ovalize distributes, long axis direction is northwest (NW)--east southeast to, be about 4.0km, the long nearly 2.0km of minor axis, the about 8.0km2 of area, the oval major axis direction of groundwater flow distributing of Cr6+ is consistent, along the content of major axis Cr6+, by north-north-west, to south-south-east, is reduced gradually.

2. hydraulic capture concrete engineering

A hydraulic capture engineering basis ash hydrogeological conditions, underground water Cr6+ distribution characteristics, stacks the pumping and drilling of trip construction after the match at flyash and forms hydraulic capture band, extracts polluted underground water out, form groundwater pollution hydraulic capture band, guarantee downstream underground water water quality safety.Engineering head of district 1200m, wide 900m, area 1.08km2.Experiment and demonstration engineering is comprised of 17 borings: 5 of pumping and drillings, drilling depth 55-60m; 12 of observation borings, drilling depth 50-60m.Hydraulic capture strip length 990m, width 780m, disturbs total drawdown value 11.60-12.20m.

3. hydraulic capture technique effect

Hydraulic capture technique water correction is respond well.Cr6+ clearance 93.51-97.98%, average 95.11%.

Claims (5)

1. the hydraulic capture method based on PRB joint control removal groundwater pollutant, is characterized in that, comprises the steps:

1) determine position, the scale of source of pollution, define the principal pollutant in underground water; Find out the distribution characteristics of distributional pattern, scope and the Pollutant levels of pollution of underground aquifers plumage;

2) collection research district hydrogeologic data, determines study area hydrogeological parameter, comprises permeability coefficient, specific yield, infiltrates supply coefficient;

3), according to place hydrogeological conditions, determine and comprise scale, form, intercepting and capturing well pump-out, the quantity of intercepting and capturing well and the spacing of hydraulic capture band, the maximum significant parameter of intercepting and capturing width and stationary point;

4) according to the form of Pollution Plume, size, determine effective spacing of intercepting and capturing band and PRB, guarantee effective joint control and remove underground water pollutant.

2. the hydraulic capture method based on PRB joint control removal groundwater pollutant as claimed in claim 1, is characterized in that, the definite of capture region width is specially:

The width 2y of capture region _lwith pumped well flow there is the relation shown in following formula in Q:

$2y_L=\±\frac{Q}{\mathrm{KBi}}$ Formula (1)

Wherein, Q-pump-out, m ³/ d; K-permeability coefficient, m/d; B-waterbearing stratum thickness, m; I-hydraulic gradient.

3. as claimed in claim 1ly based on removing the hydraulic capture method of groundwater pollutant with PRB joint control, it is characterized in that the determining of stationary point:

Distance x between stationary point and pumped well _lwidth 2y with pumped well flow Q, capture region _lthere is following relation:

$x_L=-\frac{Q}{2\mathrm{\πKBi}}=\frac{y_L}{2\mathrm{\π}}$ Formula (2).

4. as claimed in claim 1ly based on removing the hydraulic capture method of groundwater pollutant with PRB joint control, it is characterized in that the determining of hold range boundary water mechanical equation:

Direction of groundwater flow is parallel with X-axis, but flows to X-axis negative direction, and pumped well is arranged in Y-axis, and calculating hold range boundary water mechanical equation can be written as:

$Y=\±\frac{Q}{2\mathrm{BV}}-\frac{Q}{2\mathrm{\πBV}}\mathrm{ta}{n}^{-1}\frac{Y}{X}$ Formula (3)

In formula, V is local ground watering seepage velocity, m/d; Other symbol cotypes (1).

5. the hydraulic capture method based on PRB joint control removal groundwater pollutant as claimed in claim 1, is characterized in that, for Duo Koujing, the result superposition of every a bite well gained is got up, and obtains its numerical solution; For Duo Koujing, all hydraulic capture pumped wells should be on y axle aligning and distributing with origin symmetry, when n is odd number, a glance well in bosom should be arranged on initial point, its well spacing D can calculate by (4) formula

$D=\frac{1.2Q}{\mathrm{BV}}$ Formula (4).

Images