DE19856548A1 - New process to remove liquid subsoil contaminants - Google Patents

Abstract

A process to decontaminate soil is new, and the area concerned is subdivided into overlapping circles of diameter D, each of 10 m. A well (B) is sunk at the center of each circle to a depth into the impermeable layer of rock or soil. Liquid pollutants and contaminated ground water are then removed using a pump. A process to decontaminate soil is new, and the area concerned is subdivided into overlapping circles of diameter D, each of 10 m. A well (B) is sunk at the center of each circle into the impermeable layer of rock or soil. Liquid pollutants and contaminated ground water are then removed using a pump. Following treatment to remove contaminants, the water is allowed to percolate back into the soil from which it was removed, by pumping water back to the surface and returning it to the soil. The water flow is non-turbulent and laminar. Liquid contaminants are not fully removed, but the remaining contaminants are broken down by oxygen, transported by water to the sub- surface layers. The process may be accelerated by mixing the water with suitable nutrients. The liquid contaminants and contaminated water are removed from the site for disposal.

Description

Description of an environmental damage

Environmental damage is often from easy to difficult in water soluble, solid and liquid pollutants and their gases, caused by infiltration into the subsoil and groundwater.

In the cavities of the ground, the air is contaminated. With the onset of weather lows, some of the contaminated air escapes into the atmosphere. At the water level of the groundwater, a larger proportion of noxious gas absorbed.

When sinking the usually specific heavier liquid pollutants as water, the groundwater flowing by is water-soluble Shares contaminated. This jet of contaminated groundwater remains unchanged Part of the groundwater flow. Between this jet and the surrounding water will neither Liquid still exchanged chemical substance.

The watertight sole of the groundwater stream is in the flow direction slightly inclined. The sunken liquid pollutants are spreading slowly out on the sloping surface. On the sole remains a thinner Backing of liquid pollutants. Troughs and hollows remain filled with liquid pollutant.

The gutters and troughs have been pumped with pumps so far. With the usual pumps can not be sucked off directly at the bottom. Because of disproportionately high costs can be the inevitable remainder only partially pumped out.

In controls, it was found that the various remaining on the sole of remaining harmful compounds mutually are reactive. There were new connections z. B. carcinogenic vinyl chloride.  

Explanation to the patent application

With the procedure used so far the damage could at best only diminished because of the deteriorating cost-benefit Relationships, but never be completed successfully.

In the new process, the contaminated groundwater also pumped out, but not at individual focal points, but successively in subareas.

In the subareas, the liquid pollutants and contaminated groundwater withdrawn from one pump sump each, which by drilling in the waterproof sole of the groundwater stream is admitted.

The liquid pollutant is deducted to "the last millimeter". The suction distance for the well is limited to a maximum of 5 meters.

The distances of the wells are set so that the damaged area is completely covered. There will be small coverages the circular surfaces accepted. On page 3 are the mutual Assignments of the areas specified.

The purified water will be at the earth's surface above the same Part of the area seeped. It is only pumped out so much water that the seeped water flows towards the pump in the circuit laminar.

The special features of the laminar flow:
The liquids flow in layers at different speeds.
Brownian motion in layers at different speeds.
Brownian motion is not affected.
Between the layers and between the contact surfaces, neither liquids nor chemical matter are exchanged.
At the contact surfaces, the difference in kinetic energy is compensated by internal friction.

The sections contain only "clouds" with purified water.

By arranging the holes according to the proposal Page 3 the environmental damage can be remediated.  

Mutual arrangement of wells:

B = well,
○ = well axis,
D = diameter of the cylinder with purified groundwater (m),
L = mutual distance of the wells

= 2 × √ (0.5 D) ² - (0.25 D) ² = 2 × √0.1875 D 2 - 0.0625 D 2 = 2 × 0.433 D = 0.866 D,

A = areas
of the circle: F = D 2 × 3.14: 4 = 0.786 × D 2
of the hexagon in a circle = 0.650 × D²

example The area of damage and the operating result

length 160 m width 100 m Area of the damaged area 16,000 m² Waterproof sole under terrain 18 m Water level under terrain 4 m water depth 14 m Diameter of a section D = 10 m Max. Suction line on the sole = 5 m Base area of the subarea @ A = D 2 × pi; 4 = 100 × 3.14: 4 = 314: 4 = 78.6 m³ Volume of the water-filled subarea @ V = 14 × 78.5 = 1099 m³ Void ratio 0.3 Amount of water in one subarea @ V = 1099 × 0.3 = 330 m³ Water consumption for 4 times Rinse V = 4 × 330 = 1320 m³ Area of the hexagon in a subarea @ A = 0.660 × D 2 = 0.660 × 100 = 66 m² Volume above the water-filled hexagon @ V = 14 × 66 = 924 m³ Amount of water over a water. Hexagon@ V = 924 × 0.3 = 277 m³ Amount of water in the damaged area @ V = 16,000 × 14 × 0.3 = 67 200 m³ Number of wells needed 67 299: 277 = n = 243

In order to achieve the rehabilitation, the total amount of contaminated water in the area must be

n = 4 × 330 m × 243 sections: 67 200 m³ = 4.77 times

prepared and exchanged.  

State of the art

So far, the pollutants were as dissolved substance by pumping removed from the area. By this pumping is the Concentration of pollutants in the large amount of contaminated Groundwater only slightly reduced.

In most areas the remediation was discontinued if After years of pumping it had to be established that the big one Effort for the renovation could no longer be responsible.

For example, in an approximately 16 000 m² industrial area in the period from 1978 to 1994 overall in the order of magnitude approx. Pumped 6 million cbm of contaminated groundwater.

In the adjacent residential area by pumping of approx. 2.8 million cbm contaminated groundwater only about 3.1 t pollutant away. It dominates dichloroethene and the carcinogen Vinyl chloride.

The Office for Environmental Monitoring in Hanover has to 23 05. 1997 to this process (residential area only) informed that decided as follows has been:

"Because of the high cost of continuing the action of more than 13 million DM is under consideration of all circumstances. , , decided not to continue the groundwater remediation.

Technical alternatives to the previous hydraulic methods, with the elimination of such a stretch at a reasonable cost Groundwater contamination is to be achieved, are not yet known."

Claims (3)

1. Measures for remedying environmental damage:
The damaged area is subdivided into subareas. The base area of the subregions are circles with the diameter D = <10 m. Wells are created in the center of the bases. The liquid pollutants and the contaminated groundwater are sucked out of pump sumps, which are used by deep drilling into the waterproof sole. This ensures that the liquid can be completely sucked off.
The treated water is seeped back to the surface over the same sub-area and returned to the pump for 48 hours. - The water flows swirl-free, laminar -.
The liquid pollutants can not be completely detected. The inevitable residue is degraded by the biological self-purification of oxygen-saturated, purified water. This purification process can be accelerated by enriching the purified water with appropriate nutrients,
characterized in that the liquid pollutants and the contaminated water are removed from the subregions. 2. Measures for the remediation of environmental damage in accordance with Claim 1, characterized, that residual pollutants degraded by self-cleaning become. 3. Measures for remedying environmental damage in accordance with Claims 1 and 2, characterized, that the redeveloped subareas are lined up comprehensively, the area is rehabilitated.