BTEX Contamination and Remediation

Download BTEX Contamination and Remediation

Post on 10-Mar-2015

248 views

Category:

Documents

3 download

Embed Size (px)

DESCRIPTION

BTEX -Contamination and RemediationSEMINAR REPORT BTEX-CONTAMINATION AND REMEDIATIONSubmitted By MANASY PURUSHOTHAMAN PILLAI Guided By Ms. ANU CHERIAN DEPARTMENT OF CIVIL ENGINEERING MUSALIAR COLLEGE OF ENGINEERING AND TECHNOLOGY PATHANAMTHITTA-689645 2009-2010Dept Of Civil Engg:, M.C.E.T, Pathanamthitta1BTEX -Contamination and RemediationACKNOWLEDGEMENTI would like to extend my sincere thanks to Mr. A. Shihabudeen Prof & Head of the Department of Civil Engineering, MCET College o

TRANSCRIPT

BTEX -Contamination and Remediation

SEMINAR REPORT BTEX-CONTAMINATION AND REMEDIATION

Submitted By MANASY PURUSHOTHAMAN PILLAI Guided By Ms. ANU CHERIAN DEPARTMENT OF CIVIL ENGINEERING MUSALIAR COLLEGE OF ENGINEERING AND TECHNOLOGY PATHANAMTHITTA-689645 2009-2010

Dept Of Civil Engg:, M.C.E.T, Pathanamthitta

1

BTEX -Contamination and Remediation

ACKNOWLEDGEMENT

I would like to extend my sincere thanks to Mr. A. Shihabudeen Prof & Head of the Department of Civil Engineering, MCET College of Engineering and Technology, Pathanamthitta for his cooperation and encouragement. I express my profound gratitude to Ms. Anu Cherian (Lecturer, department of civil engineering) for her valuable guidance and wholehearted cooperation in preparation of this paper BTEX- Contamination and remediation. Without which this seminar would not have seen the light of day. I am greatful to Mrs. Sreejakunjamma (Advisor) Lecturer, department of civil engineering. Gracious gratitude to all the faculty of the Civil Engineering department & friends for their valuable advice. Above all, I thank the Almighty GOD without whose blessing; I would never have been able to complete this work successfully.

Dept Of Civil Engg:, M.C.E.T, Pathanamthitta

2

BTEX -Contamination and Remediation

ABSTRACTBTEX contamination is a threat to the mankind as well as to animals and plants. Prolonged exposure to the compounds even in small quantities is highly fatal. Due to massive usage of petroleum products, BTEX contamination is considered as one of the major environmental pollution. They are highly toxic and soluble in water and its presence will be significant hazard for all forms of life on earth. There are different advanced techniques on detections and treatments that have been developed recently. BTEX presence can be alerted to avoid the usage of contaminated water by the public. This paper presents a detailed study on BTEX contamination with effective detection methods like microchip induced laser fluorescence (LIF). The treatment of BTEX contamination has become one of the challenging techniques. The different treatment like in situ chemical oxidation (ISCO) is one of the most well developed and widely used as it needs only relatively short remediation period compared to other methods.

Dept Of Civil Engg:, M.C.E.T, Pathanamthitta

3

BTEX -Contamination and Remediation

CONTENTSLIST OF ABBREVIATIONS LIST OF FIGURES LIST OF TABLES 1. INTRODUCTION 2. BTEX2.1 COMPONENTS OF BTEX 2.2 BTEX CONTAMINATION 2.3 BTEX HEALTH EFFECTS

1 3

3. DETECTION OF BTEX CONTAMINATION3.1 RAMAN DIPSTICK METHOD 3.2 BIOASSAY METHOD 3.3 MICROCHIP INDUCED LASER FLUROSCENCE SENSOR

9

4. TREATMENT4.1 ORGANOCLAY AND CARBON TREATMENT 4.2 DIRECT PUSH GROUNDWATER CIRCULATION WELLS 4.3 REMEDIATION USING IN SITU CHEMICAL OXIDATION

16

5. CONCLUSION REFERENCES

23 24

Dept Of Civil Engg:, M.C.E.T, Pathanamthitta

4

BTEX -Contamination and Remediation

LIST OF ABBREVIATIONS

NO 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18.

ABBREVIATION BTEX COC DO DP-GCW EPA GCW ID ISCO LIF MCL MTBE PAH PMT PPA TDO TOSC TPH UV

EXPANSION Benzene, Toluene, Ethylbenzene, and Xylenes Chemical Oxidation Of Carbonates Dissolved oxygen Direct push groundwater circulation well Environmental Protection Agency Groundwater circulation well Inside diameter In situ chemical oxidation Laser-Induced Fluorescence Maximum Contaminant Levels Methyl tertiary butyl ether Polycyclic aromatic hydrocarbons Photomultiplier tubes Parts per million Toluene Dioxygenase Coupling Technical Outreach Services for Communities Total petroleum hydrocarbons Ultra violet

Dept Of Civil Engg:, M.C.E.T, Pathanamthitta

5

BTEX -Contamination and Remediation

LIST OF FIGURES

Figure 1.1 2.1 2.2 2.3 3.1(a) 3.1(b) 3.2 4.1 4.2 4.3 4.4

Name Sources of Groundwater Contamination Components of BTEX in Gasoline Different phases of contamination from a gas Station Routes Of Pollutant Intake Portable Raman spectrometer A simplified diagram of a Raman spectrometer Operation Schematic diagram of experimental apparatus organoclay and carbon treatment Typical in-well aeration application Typical ISCO Injection Injection System Process Flow Diagram

Page no 1 4 5 6 9 9 12 16 17 19 20

Dept Of Civil Engg:, M.C.E.T, Pathanamthitta

6

BTEX -Contamination and Remediation

LIST OF TABLE

Table 2.1

Name MCL set by the EPA for each compound in drinking water

Page no 7

Dept Of Civil Engg:, M.C.E.T, Pathanamthitta

7

BTEX -Contamination and Remediation

1. INTRODUCTION1.1 GENERAL As we plunge into the new millennium our environment is being polluted by different man made activities. One of the major source of water is the groundwater which is considered to be consumable without much treatment. There are numerous chemicals associated with federal, commercial, industrial, and agricultural operations that are considered hazardous to humans, animals, plants, and the ecological environment. Groundwater becomes contaminated when hazardous chemicals leak into the ground and drain through the soil matrix into aquifers. Once they reach the aquifer, chemicals either float or sink depending on their specific gravity (i.e., whether they are lighter or heavier than water). Gradually, the chemicals dissolve into groundwater and flow down gradient to impact additional aquifers, water reservoirs, land, and sea, expanding the risk to human health and the environment.

Fig1.1 Sources of Groundwater Contamination

Dept Of Civil Engg:, M.C.E.T, Pathanamthitta

8

BTEX -Contamination and Remediation Petroleum has been recognized as a potential environmental contaminant since shortly after the beginning of the Twentieth Century. Organic compounds can be a major pollution problem in groundwater. Their presence in water create hazard to public health and the environment. The term BTEX reflects that benzene, toluene, ethylbenzene and xylenes are often found together at contaminated sites. Because they are all highly toxic and soluble in water, they represent a significant hazard for humans.The main source of BTEX contamination is the leakage of gasoline from faulty and poorly maintained underground storage tanks. They are considered one of the major causes of environmental pollution because of widespread occurrences of leakage from underground petroleum storage tanks and spills at petroleum production wells, refineries, pipelines, and distribution terminals.

Dept Of Civil Engg:, M.C.E.T, Pathanamthitta

9

BTEX -Contamination and Remediation

2. BTEX2.1 GENERAL

Benzene, Toluene, Ethyl Benzene and Xylene (BTEX) are the volatile components commonly associated with petroleum products. Benzene, toluene and xylenes are found naturally in petroleum products like crude oil, diesel fuel and gasoline. Ethylbenzene is a gasoline and aviation fuel additive. Because of the high concentration of BTEX compounds in petroleum and the massive use of petroleum products as energy source, as solvents and in the production of other organic chemicals, their presence in water creates a hazard to public health and the environment. Contamination of groundwater with the BTEX compounds is difficult to remedy because these compounds are relatively soluble in water and can diffuse rapidly once introduced into an aquifer.

2.2 COMPONENTS OF BTEX

BTEX is the abbreviation used for four compounds found in petroleum products. The compounds are benzene, toluene, ethylbenzene and xylenes. These organic chemicals make up a significant percentage of petroleum products like crude oil, diesel, gasoline etc. Ethylbenzene is a gasoline and aviation fuel additive. They are also used extensively in manufacturing processes. Benzene is used in the production of synthetic materials and consumer products, such as synthetic rubber, plastics, nylon, insecticides and paints. Toluene is used as a solvent for paints, coatings, gums, oils and resins. Ethylbenzene may be present in consumer products such as paints, inks, plastics and pesticides. Xylenes are used as a solvent in printing, rubber and leather industries.

Dept Of Civil Engg:, M.C.E.T, Pathanamthitta

10

BTEX -Contamination and Remediation The BTEX chemicals are present in a standard gasoline blend in approximately 18%(w/w), and the group is considered to be the largest one that is related to any health hazards.

Fig. 2.1 Components of BTEX in Gasoline (Source: Publication of hazardous substance research centers, TOSC publications) Naphthalenes make up only 1%(w/w) of gasoline. Benzene, which is recognized as the most toxic compound among BTEX, represents 11%, toluene represents 26%, ethylbenzene 11% and xylene 52% of the total BTEX fraction in gasoline.

2.3 BTEX CONTAMINATION

BTEX contamination of soil and groundwater can occur by the accidental spill of gasoline, diesel fuel and leakage from underground storage tanks in pumping stations. Once released to the environment, BTEX can volatilize, dissolve, attach to soil particles or degrade biologically. Volatilization occurs when chemicals evaporate, allowing them to move from a liquid into the air. Volatilization of the BTEX components of gasoline commonly occurs when you pump gasoline into your car, and is responsible for the characteristic odour. This phenomenon can also occur within the air pockets present in soils. BTEX can also dissolve into water, allowing it to move in the groundwater.

Dept Of Civil Engg:, M.C.E.T, Pathanamthitta

11

BTEX -Contamination and Remediation Since BTEX can "stick" to soil particles, these chemicals move slower than the groundwater. BTEX can also dissolve into water, allowing it to move in the ground water. Because of their polarity and very soluble characteristics, BTEX will be able to enter the soil and groundwater systems and cause serious pollution problems. If oxygen is present in sufficient quantities, BTEX can also degrade biologically, though very slowly.

Fig. 2.2 Different phases of contamination from a gas station (Source: Publication of hazardous substance research centers, TOSC publications)

Dept Of Civil Engg:, M.C.E.T, Pathanamthitta

12

BTEX -Contamination and Remediation 2.4 BTEX HEALTH EFFECTS

Exposure to BTEX can occur by ingestion, inhalation or absorption through the skin. Inhalation of BTEX can occur while pumping gasoline or while showering or bathing with contaminated water. Absorption of these chemicals can occur by spilling gasoline onto one's skin or by bathing in contaminated water. Acute exposures to high levels of gasoline and its BTEX components have been associated with skin and sensory irritation, central nervous system depression and effects on the respiratory system.

Fig 2.3 Routes Of Pollutant Intake (Source: Publication of hazardous substance research centers, TOSC publications)

These levels are not likely to be achievable from drinking contaminated water, but are more likely from occupational exposures. Prolonged exposure to these compounds causes the kidney, liver and blood systems disorder. According to the U.S. Environmental Protection Agency (U.S. EPA), there is sufficient evidence from both human and animal studies to believe that benzene is a human carcinogen. Workers exposed to high levels of benzene in occupational settings were found to have an increase incidence in leukaemia.

2.5 BTEX REGULATIONS

Dept Of Civil Engg:, M.C.E.T, Pathanamthitta

13

BTEX -Contamination and Remediation

The U.S. EPA has established permissible levels for chemical contaminants in drinking water supplied by public water systems. These levels are called Maximum Contaminant Levels (MCLs). To derive these MCLs, the US EPA uses a number of conservative assumptions, thereby ensuring adequate protection of the public. The MCL is set so that a lifetime exposure to the contaminant at the MCL concentration would result in no more than 1 to 100 (depending on the chemical) excess cases of cancer per million people exposed.

Table2.1 MCL set by the EPA for each compound in drinking water

Chemicalbenzene toluene ethylbenzene xylene (total)

MCL (mg/liter or ppm)0.005 1 0.7 10

(Source: Publication of hazardous substance research centers, TOSC publications)

Dept Of Civil Engg:, M.C.E.T, Pathanamthitta

14

BTEX -Contamination and Remediation

2.6 REDUCING EXPOSURE TO BTEX

The U.S. EPA recommends that exposure to BTEX be minimized. To avoid or reduce exposure to BTEX, people should use water supplies having concentrations of these compounds that are below the MCL or apply appropriate water treatment or filtration systems. If necessary, short-term reductions in exposure may be accomplished by using bottled water for food and beverage preparation and avoiding bathing or showering with the contaminated water. With in-home treatment processes, such as activated charcoal filtration, it is usually possible to remove sufficient BTEX from water to meet the MCL and thereby minimize health risks. If benzene is present above the MCL, treatment should be applied to all household water because of inhalation hazards.

Dept Of Civil Engg:, M.C.E.T, Pathanamthitta

15

BTEX -Contamination and Remediation

3. DETECTION OF BTEX CONTAMINATIONSince the BTEX compounds are very toxic to humans and aquatic life, their sensitive and rapid determination is of critical importance. There are many established methods for determining BTEX contaminants in water, namely liquid-liquid extraction, solid phase extraction, gas chromatography, air stripping etc. But these methods exhibit high levels of sensitivity and selectivity. So they require well-trained personnel for its successful operation. If a small error occurs during sampling, the analytical result obtained using the best instrument will be inevitably wrong. Most existing methods for detecting BTEX are time-consuming, complicated and very expensive for routine screening. Also these methods require skill for its operation. There has been a lot of development in this area recently and many advanced techniques for the detection of BTEX contaminations have been developed. The use of lasers and optic fibers are some among them.

Some advanced techniques of detection of BTEX contamination are: 1. Raman Dipstick method 2. Bioassay method 3. Detection using Microchip Induced Fluorescence Sensor

Dept Of Civil Engg:, M.C.E.T, Pathanamthitta

16

BTEX -Contamination and Remediation

3.1 RAMAN DIPSTICK METHOD

Raman dipstick method is the detection of BTEX contamination using long path length fiber optic Raman dipstick. Determination of BTEX components via optical remote sensing is attractive because eliminates many of the problems in other established methods. Samples are interrogated through the long-path length dip-stick. It is directly inserted into the liquid of interest or an extension hose is attached to the end of the dipstick...

Recommended

View more >