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Feasibility Test of Applying Complex Remediation Technology for Diesel Contamination in Soil and

Groundwater

2012 International Conference on Environmental Quality Concern, Control and Conservation(2012EQC)

Szu-Ping Tseng*, Wen-Chi Lai, Ping-Wan Yang, Yi-Cheng Chou, Pao-Wen Liu, Yi-Minh Kuo

Graduate Student of the Department of Marine Graduate Student of the Department of Marine Environmental Engineering, National Kaohsiung Marine Environmental Engineering, National Kaohsiung Marine

University, Kaohsiung 81157, Taiwan.University, Kaohsiung 81157, Taiwan.

2525thth MAY 2012 MAY 2012

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Contents

Introduction1

Materials and Methods2

Results and Discussion3

Conclusion 4

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Introduction

Fig. 1 Amount of controlled gas stations in the last five years3

Introduction

These underground storage tanks leaking will contaminate the surrounding soil and groundwater, it will cause severe impact on the environment and increase health risk.

Therefore, we need a good method to remediate the contaminated soil and groundwater.

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A complex technology is proposed to deal with the problems.

The complex technology adopted in this study integrates the dual-phase extraction and the advanced oxidation with ozone.

Ozone (O3) is selected because it is highly oxidative and will not cause secondary contamination.

Advantages of the dual-phase extraction able to eliminate vapor, residual and dissolved phases of contaminants in polluted soil and groundwater.

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Fig. 2 Illustration of column experiment

Experimental Setup

Dual-Phase Extraction Unit

Oil/water separation tank: underground water drawn goes through the oil/water separation tank to remove floating oil.

Oil/water separation tank: underground water drawn goes through the oil/water separation tank to remove floating oil.

Advanced oxidation process equipment: uses pure oxygen as air intake for ozone, and its maximum production is 5.0 g/h, concentration is 70 g/Nm3, and power consumption is 0.15 kw.

Advanced oxidation process equipment: uses pure oxygen as air intake for ozone, and its maximum production is 5.0 g/h, concentration is 70 g/Nm3, and power consumption is 0.15 kw.

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Remediation procedure

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Parameters to be monitored

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Contaminants in soils

Simulated initial TPHd concentration was 1,760 mg/kg in soil of the dual-phase extraction column.

Simulated initial TPHd concentration was 1,760 mg/kg in soil of the dual-phase extraction column.

The above results indicate that the major contaminant polluting the soil is the TPH with high carbon counts of C10-C40. Thus, the experiment will use TPH as diesel (TPH-d) as primary analysis indicator for studies.

The above results indicate that the major contaminant polluting the soil is the TPH with high carbon counts of C10-C40. Thus, the experiment will use TPH as diesel (TPH-d) as primary analysis indicator for studies.

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Experimental soil column

TPH-d changes in soil in experimental column

TPH Standard Of Soil

The initial concentration of in-situ polluted soil was 1,760 mg/kg.

The initial concentration of in-situ polluted soil was 1,760 mg/kg.

After process of 15 runs (34 days), it decreased to below regulatory limit (1,000 mg/kg).

After process of 15 runs (34 days), it decreased to below regulatory limit (1,000 mg/kg).

The analysis results of TPH-d after process of 33 runs below detecting limit (N.D. < 57 mg/kg) with a degradation rate of approximately 95%.

The analysis results of TPH-d after process of 33 runs below detecting limit (N.D. < 57 mg/kg) with a degradation rate of approximately 95%.

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Groundwater experimental column

Experimental Runs

0 5 10 15 20 25 30 35

TP

Hd in

Gro

undw

ate

r (m

g/L

)

0

2

4

6

8

10

12

14

16

18

20

TPHd Standard of

Groundwater

TPH-d content in groundwater after oil/water separation tank

The initial results indicate that by directly oxidizing with O3 the TPH-d in groundwater, its concentration can be below detectable limits after treatment.

The initial results indicate that by directly oxidizing with O3 the TPH-d in groundwater, its concentration can be below detectable limits after treatment.

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Experimental Runs

0 10 20 30 40 50

Che

mic

al O

xyge

n D

eman

d (m

g/L)

0

100

200

300

400

500

COD Standard of Groundwater

After oil/water separation tank

COD content in groundwater

The initial COD concentration was 396 mg/L

The initial COD concentration was 396 mg/L

Consistent with the 100 mg/L effluent standard regulated in the Water Pollution Control Act.

Consistent with the 100 mg/L effluent standard regulated in the Water Pollution Control Act.

It’s value further decreased to 20~30 mg/L with an average of approximately 25 mg/L.

It’s value further decreased to 20~30 mg/L with an average of approximately 25 mg/L.

Chemical oxygen demand (COD) in groundwater

But as the concentration of organic substances decreased, this result is consistent with the trend of COD.

But as the concentration of organic substances decreased, this result is consistent with the trend of COD.

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Experimental Runs

5 10 15 20 25 30 35

Con

cent

ratio

n (m

g/L)

0

5

10

15

20

25DO in groundwaterDO in treated groundwaterUpper Detection Limit

D.O. content in groundwater

2.49-7.69 mg/L, with an average of 4.04 mg/L

2.49-7.69 mg/L, with an average of 4.04 mg/L

After AOP, it increases to above 20.0 mg/L

After AOP, it increases to above 20.0 mg/L

Further, the upper limit of the D.O. meter used in the experiment is 20.0 mg/L, and the D.O. after AOP exceeds this limit, indicating that the D.O. of the treated groundwater is saturated because O3 had decomposed into oxygen.

Further, the upper limit of the D.O. meter used in the experiment is 20.0 mg/L, and the D.O. after AOP exceeds this limit, indicating that the D.O. of the treated groundwater is saturated because O3 had decomposed into oxygen.

Dissolved oxygen (D.O.) in groundwater

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ConclusionThis study used a soil column to simulate

the actual pollution of a site, and the complex remediation technology to treat polluted soil and groundwater.

The performance results show a TPHd degradation rate of above 95% in soil.

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The groundwater COD data indicate treatment results are within legal standards.

If this can be further applied in in-situ pilot, the operating parameters of its in-situ application can be rectified and the potential limiting factors can be examined.

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