DE19753305A1 - Ground water treatment with concentrated effect on local pollutants - Google Patents

Abstract

Removal of soil sub-surface impurities involves subdividing the soil area into squares of side-length L (m) and depth T (m), covering the first water-impermeable layer, in sectors with a pore volume (Vu) of 0.3, where Vu(m<3>) = L<2> x T x 0.3(m<3>). Clean water is pumped along the water-impermeable layer, and the impurities and the contaminated ground water are exchanged for cleaned ground water.

Description

The experience is used that only narrowly limited, small areas of damage can be renovated cost-effectively.

The liquid pollutants seep vertically into the pores of the soil. The mostly sparingly soluble parts become daily through the groundwater transported in the order of decimeters. The bigger one The amount of liquid pollutants is soon removed at a short distance on the waterproof sole encountered. The clouds are through the bottom little influence on water, they are not degraded after years.

The renovation is achieved by reversing the processes described. In the partial areas, the contaminated liquid is passed through in succession Displacement of treated groundwater displaced. The process will by pumping the contaminated liquid out of the well 1 at the Sole of the partial areas accelerated.

To relieve the strainer for liquid pollutants, it is suggested to start pumping water from well B2 when purified groundwater is extracted from well 1.

If the soil conditions change, the procedure can be changed the delivery rate of the pumps and associated adjustment of the duration of the Pump operation can be optimized in each case.

Adhesive pollutants adhering to the filter grain can be washed cannot be recorded. If necessary, a necessary improvement can be made can be achieved by vaccination. The harmful effects can be reduced by Oxidation, bacterial exposure but also by changing the chemical Structure of the harmful substance can be enforced.  

example The damaged area

Length: 160 m
Width: 100 m
Area: 16,000 m ²

waterproof sole u. Gel. Ok .: 18 m
Water level u. Gel. Ok .: 4 m
Contaminated masses:
Groundwater: 16,000 x 14 x 0.3 = 67 200 m ³

Soil; 16,000 × 18 = 288,000 m ³

.

Square sub-areas

Side length: 10 m
Floor area: 100 m ²

Waterproof sole u. Gel. Ok .: 18 m
Pore volume:
Vu = 1800 × 0.3 = 540 m ³

.

example Operating profit

In the sub-areas, each:

Rinse water from well 1:
Q1 = 2 × Vu = 2 × 540 m ³ = 1080 m ³
Rinse water from well 2:
Q2 = Q1 1080 m ³
total: 2160 m ³
Pump 1 duration: 4 days
Pump 2: 2 days
Pump 1 output: 11.25 m ³ / h
Pump 2: 22.75 m ³ / h
total: 34 m ³ / h.

For the damaged area:

Total rinse water:
Q = 4 × 288,000 × 0.3 = 345,600 m ³ .

Duration of the renovation:
160 × 4 days = 560 days.

Advantages over known methods

The contaminated liquid is in the subareas on the water pumped out dense sole. As a result, deposited pollutants are included Priority vacuumed. The cleaned groundwater is no longer discharged, it is seeped away on the surface of the same section.

This process is accomplished by pumping out the contaminated liquid at the waterproof sole accelerates. The emerging "cloud" with purified water is against change in concentration by the water present is just as resistant as the "cloud" with dissolved pollutants. This manipulation is only possible with narrowly limited "clouds" possible. For this reason, the damaged area is divided into sub-areas.

In the sub-areas, the contaminated liquid is at the four corner points ten of the squares and subtracted in the middle of the field. By lining up the quadratic areas is achieved that only two Brun must be sunk. With a 10 × 10 m base area the suction path is only 5 m long.

It may be necessary to vaccinate the cleaned groundwater if there are residues must be removed from carcinogenic pollutants.

The quality of the water treatment is not entirely good during the renovation reached. The quality can be checked after each processing of a section the renovation can be checked. By adjusting Flow rate and duration of the pumping operation can be the quality of the Remediation can be corrected at any time.  

STATE OF THE ART

So far, the pollutants have been removed as a solute by pumping the damaged area. By this pumping out the concentration of pollutants in the large amount of contaminated groundwater only slightly reduced.

In most of the damaged areas, the remediation was stopped if after Years of pumping it had to be determined that the great effort for the Remediation could no longer be responsible.

For example, in an industrial area of approx. 16,000 m ² between 1978 and 1994, a total of approx. Pumped out 6 million cbm of contaminated groundwater.

In the adjoining residential area, about 2.8 Millions of cubic meters of contaminated groundwater only removed about 3.1 tons of pollutants. Dichloroethene and the carcinogenic vinyl chloride dominated.

The Office for Environmental Monitoring in Hanover announced on May 23, 1997 (only residential area) that this decision was made as follows:
"Because of the high costs for the continuation of the measure of more than DM 13 million, considering all the circumstances ... it was decided not to continue the groundwater remediation.

Technical alternatives to the previous hydraulic processes, with the removal of such at reasonable cost extensive groundwater pollution has not yet been achieved known".

Claims (5)

1. A method for the remediation of environmental damage, characterized in that the damaged area is divided into partial areas with the pore volume (0.3) by square partial areas with the side length L (m) and depth position T (m) of the waterproof sole below the surface of the site becomes:
Vu (m ³ ) = L ² × T × 0.3 (m ³ ). 2. The method according to claim 1, characterized, that the soil filter in the sub-areas by cleaned ground water is rinsed off and the pollutants as well as the contaminated Groundwater can be exchanged for purified groundwater. 3. The method according to claims 1 and 2, characterized in that in a partial area on the sole from a well to be sunk (B1), twice the amount of contaminated groundwater V1 = 2 Vu (m ³ ) is pumped out, after treatment, in the same partial area , is evenly distributed on the surface of the earth, seeps away. 4. The method according to claims 1 to 3, characterized, that subsequently at a corner point of the same square Part of the well not yet used (B2) the same amount of contaminated liquid, but with double Conveying capacity, pumped out and on the surface of the part area is also infiltrated. 5. The method according to claims 1 to 4, characterized, that the treated water is vaccinated before it seeps away can.