BTEX Contamination and Remediation

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

 Dept Of Civil Engg:, M.C.E.T, Pathanamthitta 11

SEMINAR REPORT SEMINAR REPORT

BTEX-CONTAMINATION AND REMEDIATION BTEX-CONTAMINATION AND REMEDIATION

Sub

Sub_{mitted Bymitted By} MANASY

MANASY _PURUPURUSHOTHAMANSHOTHAMAN _PILLPILLAA_II

G

Guu_{ided Byided By} Ms.

Ms. ANAN_{U CU C}HEHE_RIRIANAN

DEPARTMENT OF CIVIL ENGINEERING DEPARTMENT OF CIVIL ENGINEERING

M

M_UUSASA_LILIAA_{R CR C}OO_LLLLEGEEGE OFOF ENGENG_II NEE NEE_RIRI NG NG ANDAND TETE_CCHNOHNO_LLOGYOGY

P

PATHANAMTHATHANAMTH_IITTA-689645TTA-689645

200

ACKNOWLEDGEMENT

ACKNOWLEDGEMENT

I would like to extend my

I would like to extend my

ss

_{incere thank} 

_{incere thank} 

ss

_to

_to

_{Mr. A. Shihabudeen}

_{Mr. A. Shihabudeen}

_Prof 

_Prof 

&

&

HH

_{ead of the}

_{ead of the}

DD

_{epartment of Civil}

_{epartment of Civil}

EE

_ngineering,

_ngineering,

MM

_C

_C

ETET

_{College of} 

_{College of} 

E

E

_{ngineering and}

_{ngineering and}

TT

_{echnology, Pathanamthitta for hi}

_{echnology, Pathanamthitta for hi}

ss

_{cooperation and}

_{cooperation and}

encouragement

encouragement

..

I expre

I expre

ssss

_{my profound gratitude to}

_{my profound gratitude to}

_{Ms. Anu Cherian}

_{Ms. Anu Cherian}

_(Lecturer,

_(Lecturer,

department of civil engineering) for her valuable guidance and wholehearted

department of civil engineering) for her valuable guidance and wholehearted

cooperation in preparation of thi

cooperation in preparation of thi

ss

_{paper ³B}

_{paper ³B}

TEX-TEX-

_{Contamination and}

_{Contamination and}

remediation´

remediation´

..

_{Without which thi}

_{Without which thi}

ss ss

_{eminar would not have}

_{eminar would not have}

ss

_{een the light of} 

_{een the light of} 

day

day

..

I am greatful to

I am greatful to

Mrs. Sreejakunjamma

Mrs. Sreejakunjamma

((

AA

_dvi

_dvi

ss

_{or) Lecturer,}

_{or) Lecturer,}

department of civil engineering

department of civil engineering

..

G

G

_raciou

_raciou

ss

_{gratitude to all the faculty of the Civil}

_{gratitude to all the faculty of the Civil}

EE

_ngineering

_ngineering

department & friend

department & friend

ss

_{for their valuable advice}

_{for their valuable advice}

.. A

A

  _{bove all, I thank the}

  _{bove all, I thank the}

AA

_lmighty

_lmighty

GODGOD

_{without who}

_{without who}

ss

_{e ble}

_{e ble}

ssss

_{ing; I}

_{ing; I}

would never have been able to complete thi

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

 Dept Of Civil Engg:, M.C.E.T, Pathanamthitta 33

ABSTRACT

ABSTRACT

B

B

TEXTEX

_{contamination i}

_{contamination i}

ss

_{a threat to the mankind a}

_{a threat to the mankind a}

ss

_{well a}

_{well a}

ss

_{to animal}

_{to animal}

ss

and plant

and plant

s.s.

_{Prolonged expo}

_{Prolonged expo}

ss

_{ure to the compound}

_{ure to the compound}

ss

_{even in}

_{even in}

ss

_{mall quantitie}

_{mall quantitie}

ss

_ii

ss

highly fatal

highly fatal

..

D

D

_{ue to ma}

_{ue to ma}

ssss

_{ive u}

_{ive u}

ss

_{age of petroleum product}

_{age of petroleum product}

ss

_,,

_BTEX

_BTEX

_{contamination i}

_{contamination i}

ss

con

con

ss

_{idered a}

_{idered a}

ss

_{one of the major environmental pollution}

_{one of the major environmental pollution}

.. TT

_{hey are highly}

_{hey are highly}

toxic and

toxic and

ss

_{oluble in water and it}

_{oluble in water and it}

ss

_pre

_pre

ss

_{ence will be}

_{ence will be}

ss

_{ignificant hazard for all}

_{ignificant hazard for all}

form

form

ss

_{of life on earth}

_{of life on earth}

.. T

T

_{here are different advanced technique}

_{here are different advanced technique}

ss

_{on detection}

_{on detection}

ss

_{and treatment}

_{and treatment}

ss

that have been developed recently

that have been developed recently

..

_B

_B

TEXTEX

_pre

_pre

ss

_{ence can be alerted to avoid}

_{ence can be alerted to avoid}

the u

the u

ss

_{age of contaminated water by}

_{age of contaminated water by the public}

_{the public}

.. TT

_hi

_hi

ss

_{paper pre}

_{paper pre}

ss

_ent

_ent

ss

_{a detailed}

_{a detailed}

s

s

_{tudy on B}

_{tudy on B}

TEXTEX

_{contamination with effective}

_{contamination with effective detection method}

_{detection method}

ss

_like

_like

microchip induced la

microchip induced la

ss

_{er fluore}

_{er fluore}

ss

_cence

_cence

_(LIF)

_(LIF)

.. TT

_{he treatment of B}

_{he treatment of B}

TEXTEX

contamination ha

contamination ha

ss

_{become one of the challenging technique}

_{become one of the challenging technique}

s.s. TT

_{he different}

_{he different}

treatment like in

treatment like in

ss

_{itu chemical oxidation}

_{itu chemical oxidation}

_(ISCO)

_(ISCO)

_ii

ss

_{one of the mo}

_{one of the mo}

ss

_{t well}

_{t well}

developed and widely u

developed and widely u

ss

_ed

_{ed aa}

ss

_{it need}

_{it need}

ss

_{only relatively}

_{only relatively}

ss

_{hort remediation}

_{hort remediation}

 period compared to other method

 period compared to other method

s.s.

CONTENTS

CONTENTS

LIST OF ABBREVIATIONS

LIST OF ABBREVIATIONS

LIST OF FIGURES

LIST OF FIGURES

LIST OF TABLES

LIST OF TABLES

1.

1. INTRODUCTION

INTRODUCTION

1

1

2.

2. BTEX

BTEX

3

3

2.1 COMPONENTS OF BTEX 2.1 COMPONENTS OF BTEX 2.2 BTEX CONTAMINATION 2.2 BTEX CONTAMINATION 2.3 BTEX HEALTH EFFECTS 2.3 BTEX HEALTH EFFECTS

3.

3. DETECTION

DETECTION OF

OF BTEX

BTEX CONTAMINATION

CONTAMINATION

9

9

3.1 RAMAN DIPSTICK METHOD 3.1 RAMAN DIPSTICK METHOD 3.2 BIOASSAY METHOD

3.2 BIOASSAY METHOD

3.3 MICROCHIP INDUCED LASER FLUROSCENCE SENSOR  3.3 MICROCHIP INDUCED LASER FLUROSCENCE SENSOR 

4.

4. TREATMENT

TREATMENT

16

16

4.1 ORGANOCLAY AND CARBON TREATMENT 4.1 ORGANOCLAY AND CARBON TREATMENT

4.2 DIRECT PUSH GROUNDWATER CIRCULATION WELLS 4.2 DIRECT PUSH GROUNDWATER CIRCULATION WELLS 4.3 REMEDIATION USING IN SITU

4.3 REMEDIATION USING IN SITU CHEMICAL OXIDATIONCHEMICAL OXIDATION

5.

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

 Dept Of Civil Engg:, M.C.E.T, Pathanamthitta 55

LIST OF ABBREVIATIONS

LIST OF ABBREVIATIONS

NO

NO ABBREVIATION

ABBREVIATION

EXPANSION

EXPANSION

1.

1.

B

B

TEXTEX

_Benzene,

_Benzene,

TT

_oluene,

_oluene,

EE

_{thylbenzene, and}

_{thylbenzene, and}

X

X

_ylene

_ylene

ss

2.

2.

C

C

OO

_C

_C

_Chemical

_Chemical

OO

_xidation

_xidation

OO

_{f Carbonate}

_{f Carbonate}

ss

3.

3.

DODO DD

_ii

ssss

_{olved oxygen}

_{olved oxygen}

4.

4.

DD

_P

_P

-G-G

_CW

_CW

DD

_{irect pu}

_{irect pu}

ss

_{h groundwater circulation well}

_{h groundwater circulation well}

5.

5.

EE

_P

_P

AA EE

_{nvironmental Protection}

_{nvironmental Protection}

AA

_gency

_gency

6.

6.

GG

_CW

_CW

GG

_{roundwater circulation well}

_{roundwater circulation well}

7

7

_..

_II

DD

_In

_In

ss

_{ide diameter} 

_{ide diameter} 

8

8

_..

_II

SS

_C

_C

OO

_In

_In

ss

_itu

_{itu chemical oxidation}

_{chemical oxidation}

9.

9.

LI

LI

FF

_La

_La

ss

_er 

_er 

--

_Induced

_Induced

FF

_luore

_luore

ss

_cence

_cence

10.

10.

MM

_CL

_CL

MM

_{aximum Contaminant Level}

_{aximum Contaminant Level}

ss

11.

11.

MTMT

_B

_B

EE MM

_{ethyl tertiary butyl ether} 

_{ethyl tertiary butyl ether} 

12.

12.

P

P

AHAH

_{Polycyclic aromatic hydrocarbon}

_{Polycyclic aromatic hydrocarbon}

ss

13.

13.

P

P

MTMT

_{Photomultiplier tube}

_{Photomultiplier tube}

ss

14.

14.

PP

PP

AA

_Part

_Part

ss

_{per million}

_{per million}

15.

15.

TDOTDO TT

_oluene

_oluene

DD

_ioxygena

_ioxygena

ss

_{e Coupling}

_{e Coupling}

16.

16.

TOSTOS

_C

_C

TT

_echnical

_echnical

OO

_utreach

_utreach

SS

_ervice

_ervice

ss

_for 

_for 

Communitie

Communitie

ss

1

1

77

_..

TT

_P

_P

HH TT

_{otal petroleum hydrocarbon}

_{otal petroleum hydrocarbon}

ss

1

LIST OF FIGURES

LIST OF FIGURES

Figure

Figure

Name

Name

Page

Page no

no

1.1

1.1

SS

_ource

_ource

ss

_of 

_of 

GG

_roundwater

_{roundwater Contamination}

_{Contamination}

₁

₁

2.1

2.1

Component

Component

ss

_{of B}

_{of B}

TEXTEX

_in

_in

GG

_aa

ss

_oline

_oline

44

2.2

2.2

DD

_{ifferent pha}

_{ifferent pha}

ss

_ee

ss

_{of contamination from a ga}

_{of contamination from a ga}

ss 55 S

S

_tation

_tation

2.3

2.3

Route

Route

ss OO

_{f Pollutant Intake}

_{f Pollutant Intake}

66

3.1(a)

3.1(a)

Portable Raman

Portable Raman

ss

 _pectrometer 

 _pectrometer 

99

3.1(b)

3.1(b)

AA ss

_{implified diagram of a Raman}

_{implified diagram of a Raman}

ss

 _pectrometer 

 _pectrometer 

99 O

O

 _peration

 _peration

3.2

3.2

SS

_{chematic diagram of experimental apparatu}

_{chematic diagram of experimental apparatu}

ss

₁₂

₁₂

4.1

4.1

organoclay

organoclay and

and carbon

carbon treatment

treatment

1

1

66

4.2

4.2

TT

_{ypical in}

_{ypical in}

--

_well

_{well aeration}

_{aeration application}

_application

₁₇

₁₇

4.3

4.3

TT

_{ypical I}

_{ypical I}

SS

_C

_C

OO

_Injection

_Injection

₁

₁

99

4.4

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

 Dept Of Civil Engg:, M.C.E.T, Pathanamthitta 77

LIST OF TABLE

LIST OF TABLE

Table

Table

Name

Name

Page

Page no

no

2.1

2.1

MM

_CL

_CL

ss

_{et by the}

_{et by the}

EE

_P

_P

AA

_for

_{for each}

_{each compo}

_compound

_{und in}

_in

₇

₇

drinking water 

drinking water 

1. INTRODUCTION

1. INTRODUCTION

1.1 GENERAL 1.1 GENERAL

As

As _{we plunge into the new millennium our environment iwe plunge into the new millennium our environment i}ss _{being polluted bybeing polluted by}

different man made activitie

different man made activities. Os.O_{ne of the major ne of the major} ss_{ource of water iource of water i}ss_{the groundwater whichthe groundwater which}

iiss _conconss_{idered to be conidered to be con}ss_{umable without much treatmentumable without much treatment}.. TT_{here are numerouhere are numerou}ss _{chemicalchemical}ss

aassss_{ociated with federal, commercial, induociated with federal, commercial, indu}ss_{trial, and agricultural operationtrial, and agricultural operation}ss _{that arethat are}

con

conss_{idered hazardouidered hazardou}ss _{to humanto human}ss_{, animal, animal}ss_{, plant, plant}ss_{, and the ecological environment, and the ecological environment}.. G

G_{roundwater becomeroundwater become}ss _{contaminated when hazardoucontaminated when hazardou}ss _{chemicalchemical}ss _{leak into the ground andleak into the ground and}

drain through the

drain through the ss_{oil matrix into aquifer oil matrix into aquifer} s.s. OO_{nce they reach the aquifer, chemicalnce they reach the aquifer, chemical}ss _{either either} 

float or 

float or ss_{ink depending on their ink depending on their} ss _{pecific gravity (i pecific gravity (i}.._ee.._{, whether they are lighter or heavier , whether they are lighter or heavier} 

than water)

than water).. GG_{radually, the chemicalradually, the chemical}ss _didissss_{olve into groundwater and flow down gradientolve into groundwater and flow down gradient}

to impact additional aquifer 

to impact additional aquifer ss_{, water re, water re}ss_{ervoir ervoir} ss_{, land, and, land, and}ss_{ea, expanding the riea, expanding the ri}ss_{k to humank to human}

health and the environment health and the environment..

Fig1.1 Sources of Groundwater Contamination Fig1.1 Sources of Groundwater Contamination

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

 Dept Of Civil Engg:, M.C.E.T, Pathanamthitta 99

Petroleum ha

Petroleum hass _{been recognized abeen recognized a}ss _{a potential environmental contaminanta potential environmental contaminant} ss_inceince s

s_{hortly after the beginning of thehortly after the beginning of the} TT_{wentieth Centurywentieth Century}.. OO_{rganic compoundrganic compound}ss_{can be a major can be a major} 

 pollution problem in groundwater 

 pollution problem in groundwater .. TT_{heir preheir pre}ss_{ence in water create hazard to public healthence in water create hazard to public health}

and the environment

and the environment.. TT_{he term Bhe term B}TEXTEX _{reflectreflect}ss _{that benzene, toluene, ethylbenzene andthat benzene, toluene, ethylbenzene and}

xylene

xyleness _{are often found together at contaminatedare often found together at contaminated}ss_iteites.s. _BecauBecauss_{e they are all highly toxice they are all highly toxic}

and

and ss_{oluble in water, they repreoluble in water, they repre}ss_{ent aent a} ss_{ignificant hazard for humanignificant hazard for human}s.Ts.T_{he mainhe main} ss_{ource of ource of} 

B

BTEXTEX _{contamination icontamination i}ss _{the leakage of gathe leakage of ga}ss_{oline from faulty and poorly maintainedoline from faulty and poorly maintained}

underground

underground ss_{torage tank torage tank} s.s. TT_{hey are conhey are con}ss_{idered one of the major cauidered one of the major cau}ss_eess _of of 

environmental pollution becau

environmental pollution becauss_{e of widee of wide}ss _{pread occurrence pread occurrence}ss _{of leakage from undergroundof leakage from underground}

 petroleum

 petroleum ss_{torage tank torage tank} ss _andand ss _pill pillss _{at petroleum production wellat petroleum production well}ss_{, refinerie, refinerie}ss_{, pipeline, pipeline}ss_,,

and di

2. BTEX

2. BTEX

2.1 GENERAL 2.1 GENERAL

Benzene,

Benzene, TT_{oluene,oluene,} EE_{thyl Benzene andthyl Benzene and} XX_{ylene (Bylene (B}TEXTEX_{) are the volatile) are the volatile}

component

componentss _{commonly acommonly a}ssss_{ociated with petroleum productociated with petroleum product}s.s. _{Benzene, toluene andBenzene, toluene and}

xylene

xyleness _{are found naturally in petroleum productare found naturally in petroleum product}ss_{like crude oil, dielike crude oil, die}ss_{el fuel and gael fuel and ga}ss_olineoline.. E

E_{thylbenzene ithylbenzene i}ss _{a a gaga}ss_{oline and aviation fuel additiveoline and aviation fuel additive}.. _BecauBecauss_{e of the high concentratione of the high concentration}

of B

of BTEXTEX _{compoundcompound}ss _{in petroleum and the main petroleum and the ma}ssss_{ive uive u}ss_{e of petroleum producte of petroleum product}ss _aass _energyenergy s

s_{ource, aource, a}ss ss_olventolventss _{and in the production of other organic chemicaland in the production of other organic chemical}ss_{, their pre, their pre}ss_{ence inence in}

water create

water createss _{a hazard to public health and the environmenta hazard to public health and the environment}.. _{Contamination of Contamination of} 

groundwater with the B

groundwater with the BTEXTEX _{compoundcompound}ss _iiss _{difficult to remedy becaudifficult to remedy becau}ss_{e thee the}ss_{e compounde compound}ss

are relatively

are relativelyss_{oluble in water and oluble in water and can diffucan diffu}ss_{e rapidly once introduced into an aquifer e rapidly once introduced into an aquifer} ..

2.2 COMPONENTS OF BTEX 2.2 COMPONENTS OF BTEX

B

BTEXTEX _iiss_{the abbreviation uthe abbreviation u}ss_{ed for four compounded for four compound}ss _{found in petroleum productfound in petroleum product}s.s. T

T_{he compoundhe compound}ss_{are benzene, toluene, ethylbenzene and xyleneare benzene, toluene, ethylbenzene and xylene}s.s. TT_hehess_{e organic chemicale organic chemical}ss

make up a

make up a ss_{ignificant percentage of petroleum productignificant percentage of petroleum product}ss _{like crude oil, dielike crude oil, die}ss_{el, gael, ga}ss_olineoline

etc

etc.. EE_{thylbenzene ithylbenzene i}ss _{a gaa ga}ss_{oline and aviation fuel additiveoline and aviation fuel additive}.. TT_{hey are alhey are al}ss_{o uo u}ss_{ed extened exten}ss_ivelyively

in manufacturing proce

in manufacturing processss_ees.s. _{BenzeneBenzene ii}ss _uuss_{ed in the production of ed in the production of} ss_{ynthetic materialynthetic material}ss _andand

con

conss_{umer productumer product}ss_,, ss_{uch auch a}ss ss_{ynthetic rubber, playnthetic rubber, pla}ss_ticticss_{, nylon, in, nylon, in}ss_{ecticideecticide}ss _{and paintand paint}s.s.

Toluene

Toluene iiss _uuss_{ed aaed} ss _aa ss_{olvent for paintolvent for paint}ss_{, coating, coating}ss_{, gum, gum}ss_{, oil, oil}ss _{and reand re}ss_inins.s. _{EthylbenzeneEthylbenzene}

may be pre

may be press_{ent in conent in con}ss_{umer productumer product}s ss s_{uch auch a}ss _paintpaintss_{, ink , ink} ss_{, pla, pla}ss_ticticss _{and peand pe}ss_ticideticides.s.

Xylenes

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

 Dept Of Civil Engg:, M.C.E.T, Pathanamthitta 1111

T

T_{he Bhe B}TEXTEX _{chemicalchemical}ss_{are preare pre}ss_{ent in aent in a} ss_{tandard gatandard ga}ss_{oline blend in approximatelyoline blend in approximately}

1

18%8%_{(w/w), and the group i(w/w), and the group i}ss_conconss_{idered to be the largeidered to be the large}ss_{t one that it one that i}ss_{related to any healthrelated to any health}

hazard hazards.s.

Fig. 2.1 Components of BTEX in Gasoline Fig. 2.1 Components of BTEX in Gasoline

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

 N

 N_{aphthaleneaphthalene}ss _{make up only 1make up only 1}%%_{(w/w) of ga(w/w) of ga}ss_olineoline.. _{Benzene, which iBenzene, which i}ss _{recognizedrecognized}

aass _{the mothe mo}ss_{t toxic compound among Bt toxic compound among B}TEXTEX_{, repre, repre}ss_ententss ₁₁₁₁%%_{, toluene repre, toluene repre}ss_ententss ₂₂6%6%_,,

ethylbenzene 11

ethylbenzene 11%%_{and xyleneand xylene}55₂₂%%_{of the total Bof the total B}TEXTEX _{fraction in gafraction in ga}ss_olineoline..

2.3 BTEX CONTAMINATION 2.3 BTEX CONTAMINATION

B

BTEXTEX _{contamination of contamination of} ss_{oil and groundwater can occur by the accidentaloil and groundwater can occur by the accidental}ss _{pill of  pill of} 

ga

gass_{oline, dieoline, die}ss_{el fuel and leakage from undergroundel fuel and leakage from underground} ss_{torage tank torage tank} ss _{in pumpingin pumping} ss_tationtations.s. O

O_{nce releance relea}ss_{ed to the environment, Bed to the environment, B}TEXTEX _{can volatilize, dican volatilize, di}ssss_{olve, attach toolve, attach to} ss_{oil particleoil particle}ss

or degrade biologically

or degrade biologically.. _{Volatilization occur Volatilization occur} ss _{when chemicalwhen chemical}ss _{evaporate, allowing themevaporate, allowing them}

to move from a liquid into the air 

to move from a liquid into the air .. _{Volatilization of the BVolatilization of the B}TEXTEX _{componentcomponent}ss _{of gaof ga}ss_olineoline

commonly occur 

commonly occur ss _{when you pump gawhen you pump ga}ss_{oline into your car, and ioline into your car, and i}ss _reress _pon ponss_{ible for theible for the}

characteri

characteriss_{tic odour tic odour} .. TT_hihiss _{phenomenon can alphenomenon can al}ss_{o occur within the air pocketo occur within the air pocket}ss _prepress_{ent inent in} s

S

S_{ince Bince B}TEXTEX _{can "can "}ss_{tick" totick" to} ss_{oil particleoil particle}ss_{, the, the}ss_{e chemicale chemical}ss _movemove ss_{lower than thelower than the}

groundwater 

groundwater .. _BBTEXTEX _{can alcan al}ss_{o o didi}ssss_{olve into water, allowing it to move in the groundolve into water, allowing it to move in the ground}

water 

water .. _BecauBecauss_{e of their polarity and verye of their polarity and very} ss_{oluble characterioluble characteri}ss_ticticss_{, , BB}TEXTEX _{will be able towill be able to}

enter the

enter the ss_{oil and groundwater oil and groundwater} ss_yyss_temtemss_{and cauand cau}ss_eess_erioueriouss_{pollution problempollution problem}s.s._{If oxygen iIf oxygen i}ss

 pre

 press_{ent inent in}ss_{ufficient quantitieufficient quantitie}ss_{, B, B}TEXTEX _{can alcan al}ss_{o degrade biologically, though veryo degrade biologically, though very}ss_lowlylowly..

Fig. 2.2 Different phases of contamination from a gas station Fig. 2.2 Different phases of contamination from a gas station

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

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

 Dept Of Civil Engg:, M.C.E.T, Pathanamthitta 1133

2.4 BTEX HEALTH EFFECTS 2.4 BTEX HEALTH EFFECTS

E

E_xpoxposs_{ure to Bure to B}TEXTEX _{can occur by ingecan occur by inge}ss_{tion, inhalation or abtion, inhalation or ab}ss_{orption through theorption through the} s

s_kinkin.. _{Inhalation of BInhalation of B}TEXTEX _{can occur while pumping gacan occur while pumping ga}ss_{oline or whileoline or while} ss_{howering or howering or} 

  bathing with contaminated water 

  bathing with contaminated water .. AA _b bss_{orption of theorption of the}ss_{e chemicale chemical}ss _{can occur bycan occur by} ss _{pilling pilling}

ga

gass_{oline onto one'oline onto one'}ss ss_{kin or by bathing in contaminated water kin or by bathing in contaminated water} .. AA_{cute expocute expo}ss_ureuress _{to highto high}

level

levelss _{of gaof ga}ss_{oline and itoline and it}ss _BBTEXTEX _{componentcomponent}ss _{have been ahave been a}ssss_{ociated withociated with} ss_{kin andkin and} ss_enenss_oryory

irritation, central nervou

irritation, central nervouss ss_yyss_{tem depretem depre}ssss_{ion and effection and effect}ss _{on the reon the re}ss _{piratory piratory}ss_yyss_temtem..

Fig 2.3 Routes Of Pollutant Intake Fig 2.3 Routes Of Pollutant Intake

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

T

T_hehess_{e levele level}ss_{are not likely to be achievable from drinking contaminated water, butare not likely to be achievable from drinking contaminated water, but}

are more likely from occupational expo

are more likely from occupational exposs_ureures.s. _{Prolonged expoProlonged expo}ss_{ure to theure to the}ss_{e compounde compound}ss

cau

causs_eess_{the kidney, liver and bloodthe kidney, liver and blood}ss_yyss_temtemss_didiss_order order .. AA_{ccording to the Uccording to the U}.S..S. EE_{nvironmentalnvironmental}

Protection

Protection AA_{gency (Ugency (U}.S..S. EE_PPAA_{), there i), there i}ss ss_{ufficient evidence from both human and animalufficient evidence from both human and animal} s

s_tudietudiess_{to believe that benzene ito believe that benzene i}ss_{a human carcinogena human carcinogen}.. _{Worker Worker} ss _expoexposs_{ed to high leveled to high level}ss _of of 

 benzene in occupational

 benzene in occupationalss_ettingettingss _{were found to have an increawere found to have an increa}ss_{e incidence in leukaemiae incidence in leukaemia}..

2.5 BTEX REGULATIONS 2.5 BTEX REGULATIONS

T

T_{he he UU}.S..S. EE_PPAA _hahass _eess_tablitabliss_{hed permihed permi}ssss_{ible levelible level}ss _{for chemical contaminantfor chemical contaminant}ss _inin

drinking water 

drinking water ss_{upplied by public water upplied by public water} ss_yyss_temtems.s. TT_hehess_{e levele level}ss _{are calledare called  Maxim Maxim}uu_mm

Contaminant Levels

Contaminant Levels ((MM_CLCLss₎₎.. TT_{o derive theo derive the}ss_ee MM_CLCLss_{, the U, the U}SS EE_PPAA _uuss_eess _{a number of a number of} 

con

conss_{ervative aervative a}ssss_{umptionumption}ss_{, thereby en, thereby en}ss_{uring adequate protection of the publicuring adequate protection of the public}.. TT_hehe MM_CLCL

iiss ss_etet ss_{o that a lifetime expoo that a lifetime expo}ss_{ure to the contaminant at theure to the contaminant at the} MM_{CL concentration wouldCL concentration would}

re

ress_{ult in no more than 1 to 100 (depending on the chemical) exceult in no more than 1 to 100 (depending on the chemical) exce}ssss _cacass_eess _{of cancer per of cancer per} 

milli

million peoon people expople exposs_eded..

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

((SS_{ource: Publication of hazardouource: Publication of hazardou}ss ss_ububss_{tance retance re}ss_{earch center earch center} ss_,,TOSTOS_{C publicationC publication}ss₎₎

Chemical

Chemical

MCL

MCL

((mg/liter or ppm

mg/liter or ppm))

  benzene 0   benzene ..₀₀₀₀55 0 toluene 1 toluene 1 ethylbenzene 0 ethylbenzene 0..₇₇ xylene

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

 Dept Of Civil Engg:, M.C.E.T, Pathanamthitta 1155

2.6 REDUCING EXPOSURE TO BTEX

2.6 REDUCING EXPOSURE TO BTEX

T

T_{he he UU}.S..S. EE_PPAA _{recommendrecommend}ss _{that expothat expo}ss_{ure to Bure to B}TEXTEX _bebe

minimized

minimized.. TT_{o avoid or reduce expoo avoid or reduce expo}ss_{ure to Bure to B}TEXTEX_{, people, people} ss_{hould uhould u}ss_{e water e water} ss_upplieuppliess

having concentration

having concentrationss _{of theof the}ss_{e compounde compound}ss _{that are below thethat are below the MCL MCL or apply appropriateor apply appropriate}

water treatment or filtration

water treatment or filtration ss_yyss_temtems.s. _{If neceIf nece}ssss_ary,ary, ss_horthort--_{term reductionterm reduction}ss _{in expoin expo}ss_{ure mayure may}

 be accompli

 be accompliss_{hed by uhed by u}ss_{ing bottled water for food and beverage preparation and avoidinging bottled water for food and beverage preparation and avoiding}

  bathing or 

  bathing or ss_{howering with the contaminated water howering with the contaminated water} .. _{With inWith in}--_{home treatment procehome treatment proce}ssss_eess_,, s

s_{uch auch a}ss _{activated charcoal filtration, it iactivated charcoal filtration, it i}ss _uuss_{ually poually po}ssss_{ible to removeible to remove} ss_{ufficient Bufficient B}TEXTEX

from water to meet the

from water to meet the MM_{CL and thereby minimize health riCL and thereby minimize health ri}ss_k k s.s. _{If benzene iIf benzene i}ss _prepress_entent

above the

above the MM_{CL, treatmentCL, treatment} ss_{hould be applied to all houhould be applied to all hou}ss_{ehold water becauehold water becau}ss_{e of inhalatione of inhalation}

hazard hazards.s.

3. DETECTION OF BTEX CONTAMINATION

3. DETECTION OF BTEX CONTAMINATION

S

S_{ince the Bince the B}TEXTEX _{compoundcompound}ss _{are very toxic to humanare very toxic to human}ss _{and aquatic life, their and aquatic life, their}  s

s_enenss_{itive and rapid determination iitive and rapid determination i}ss _{of critical importanceof critical importance}.. TT_{here are many ehere are many e}ss_tablitabliss_hedhed

method

methodss _{for determining Bfor determining B}TEXTEX _{contaminantcontaminant}ss _{in water, namely liquidin water, namely liquid}--_{liquid extraction,liquid extraction,} s

s_{olid phaolid pha}ss_{e extraction, gae extraction, ga}ss _{chromatography, air chromatography, air} ss_{tripping etctripping etc}.. _{But theBut the}ss_{e methode method}ss _{exhibitexhibit}

high level

high levelss _of of ss_enenss_{itivity anditivity and} ss_{electivityelectivity}.. SS_{o they require wello they require well}--_{trained per trained per} ss_{onnel for itonnel for it}ss s

s_ucceuccessss_{ful operationful operation}.. _{If If aa} ss_{mall error occur mall error occur} ss _duringduring ss_{ampling, the analytical reampling, the analytical re}ss_ultult

obtained u

obtained uss_{ing the being the be}ss_{t t inin}ss_{trument will be inevitably wrongtrument will be inevitably wrong}.. MM_ooss_{t exit exi}ss_{ting methodting method}ss _for for 

detecting B

detecting BTEXTEX _{are timeare time}--_conconss_{uming, complicated and very expenuming, complicated and very expen}ss_{ive for routineive for routine} s

s_{creeningcreening}.. AAllsso theo thesse methode methodss requirerequire sskill for itkill for itss operationoperation.. TThere hahere hass been a lot of been a lot of 

development in thi

development in thiss _{area recently and many advanced techniquearea recently and many advanced technique}ss _{for the detection of for the detection of} 

B

BTEXTEX _{contaminationcontamination}ss _{have been developedhave been developed}.. TT_{he he uu}ss_{e of lae of la}ss_er er ss _{and optic fiber and optic fiber} ss _areare ss_omeome

among them among them..

S

S_{ome advanced techniqueome advanced technique}ss_{of detection of Bof detection of B}TEXTEX _{contamination are:contamination are:}

1

1.. _RamanRamanDD_ipipss_{tick methodtick method}

2

2.. _BioaBioassss_{ay methoday method} 3

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

 Dept Of Civil Engg:, M.C.E.T, Pathanamthitta 1717

3.1 RAMAN DIPSTICK METHOD 3.1 RAMAN DIPSTICK METHOD

Raman dip

Raman dipss_{tick method itick method i}ss _{the detection of Bthe detection of B}TEXTEX _{contamination ucontamination u}ss_{ing long pathing long path}

length fiber optic Raman dip

length fiber optic Raman dipss_tick tick .. DD_{etermination of Betermination of B}TEXTEX _{componentcomponent}ss _{via opticalvia optical}

remote

remote ss_enenss_{ing iing i}ss _{attractive becauattractive becau}ss_{e eliminatee eliminate}ss_{many of the problemmany of the problem}ss _{in other ein other e}ss_tablitabliss_hedhed

method

methods.s. SS_ampleampless _{are interrogated through the longare interrogated through the long}-- _{path length µdip path length µdip}-s-s_tick¶tick¶.. _{It It ii}ss _{directlydirectly}

in

inss_{erted into the liquid of intereerted into the liquid of intere}ss_{t or an extent or an exten}ss_{ion hoion ho}ss_{e e ii}ss _{attached to the end of the µdipattached to the end of the µdip} --s

s_{tick¶, providing a low protick¶, providing a low profilfile and e and more flexible meanmore flexible mean}ss_of of ss_{ample interrogationample interrogation}..

Fig3.1 (a)

Fig3.1 (a) Portable Raman spectrometer Portable Raman spectrometer  Fig3.1 (b) A simplified diagram of aFig3.1 (b) A simplified diagram of a Raman

F

F_iber iber --_opticoptic ss _{pectro pectro}ss_{copic techniquecopic technique}ss _uuss_{ed for detection include vied for detection include vi}ss_ibleible

ab

abss_{orption, infrared aborption, infrared ab}ss_{orption, fluoreorption, fluore}ss_{cence and Ramancence and Raman} ss _{pectro pectro}ss_copycopy.. OO_{f thef the}ss_ee

technique

techniquess_{, Raman, Raman} ss _{pectro pectro}ss_{copy icopy i}ss _{particularly better method for detecting Bparticularly better method for detecting B}TEXTEX

analyte

analytess _{in water becauin water becau}ss_{e it offer e it offer} ss _{a high degree of a high degree of} ss_{electivity and ielectivity and i}ss _{compatible withcompatible with}

aqueou

aqueouss _{matricematrice}s.s. EE_{ven though thiven though thi}ss _{method imethod i}ss _veryvery ss_{imple and cheaper, practically a lotimple and cheaper, practically a lot}

of problem

of problemss _{are thereare there}.. TT_{urbidity of theurbidity of the} ss_{ample could block collection of Ramanample could block collection of Raman}ss_{catteringcattering}

from the

from the ss_ampleample.. AA_llss_{o the preo the pre}ss_{ence of interfering compoundence of interfering compound}ss _{can lead to diminican lead to dimini}ss_hedhed s

s_enenss_{itivityitivity}.. _{If the interfering compoundIf the interfering compound}ss_{are fluoreare fluore}ss_{cent it will macent it will ma}ss_{k Ramank Raman}ss_ignalignals.s.

3.2 BIOASSAY METHOD 3.2 BIOASSAY METHOD

Bioa

Bioassss_ayayss _{are typically conducted to meaare typically conducted to mea}ss_{ure the effecture the effect}ss _{of aof a} ss_ububss_tancetance

on a living organi

on a living organiss_mm.. _BioaBioassss_ayayss _{may be qualitative or quantitativemay be qualitative or quantitative}.. TT_hihiss _iiss _{a quantitativea quantitative}

 bioa

 bioassss_{ay ay uu}ss_{inging PP}ss_{eudomonaeudomona}ss _putidaputida FF_{1, which ha1, which ha}ss _{been well characterized geneticallybeen well characterized genetically}

and po

and possss_eessss_eess _{a diver a diver} ss_{e metabolie metaboli}ss_{m of aromatic compoundm of aromatic compound}s.s. DD_{etection of Betection of B}TEXTEX

compound

compoundss _uuss_inging TT_olueneoluene DD_{ioxygenaioxygena}ss_{e peroxide coupling reaction ie peroxide coupling reaction i}ss _{called bioacalled bioa}ssss_ayay

method

method.. _{It It ii}ss ss_imple,imple, ss_enenss_{itive, wholeitive, whole}--_cellcell-- _ba bass_{ed bioaed bioa}ssss_ayay ss_yyss_{tem for detection of biotem for detection of bio}

--available B

available BTEXTEX _{compoundcompound}ss _babass_{ed on a method developed for ed on a method developed for} ss_{creening of oxygenacreening of oxygena}ss_ee

activity

activity.. _PPss_{eudomonaeudomona}ss _putidaputida FF_{1 1 ii}ss _{known to expreknown to expre}ssss TDOTDO _{capable of oxidizingcapable of oxidizing}

compound

compoundss _ii.._ee.._{, it i, it i}ss _{involved in the conver involved in the conver} ss_{ion of aromatic compoundion of aromatic compound}ss _{to their to their} 

corre

corress  _{ponding catechol  ponding catechol}s.s. AsAs _ppss_{eudomonaeudomona}ss _{putida iputida i}ss _{capable of both monooxygenationcapable of both monooxygenation}

and

andDD_{ioxygenaioxygena}ss_{e reactione reaction}ss _aass_{creening of oxygenacreening of oxygena}ss_{e ie i}ss_{provided uprovided u}ss_{ing whole celling whole cell}ss_yyss_temtem.. T

T_hihiss _bioabioassss_ayay ss_yyss_{tem requiretem require}ss _nono ss_ophiophiss_{ticated inticated in}ss_{trumenttrument}ss _{and exquiand exqui}ss_{ite techniqueite technique}s.s. TT_hehe

 bioa

 bioassss_{ay haay ha}ss _{long termlong term} ss_toragetorage ss_{tabilitytability} ss_{o that it can be uo that it can be u}ss_{ed for field monitoring of ed for field monitoring of} 

B

BTEXTEX _{compoundcompound}ss _{and itand it}ss _{tracking in contaminated water tracking in contaminated water} .. TT_{he convenience of multiplehe convenience of multiple} s

s_ampleample--_{handling makehandling make}ss _thithiss _{whole cell awhole cell a}ssss_{ay an attractive method to be developed aay an attractive method to be developed a}ss _aa

field diagno

field diagnoss_{tic method for ontic method for on}-s-s_{ite Bite B}TEXTEX _{contaminationcontamination}.. TT_{he main dihe main di}ss_{advantage of thiadvantage of thi}ss

method i

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

 Dept Of Civil Engg:, M.C.E.T, Pathanamthitta 1199

3.3 DETECTION USING MICROCHIP INDUCED FLUORESCENCE SENSOR  3.3 DETECTION USING MICROCHIP INDUCED FLUORESCENCE SENSOR 

M

M_ooss_{t organic moleculet organic molecule}ss_{when excited with ultra raywhen excited with ultra ray}ss_{re emit lere emit le}ssss_{energetic opticalenergetic optical}

radiation

radiation.. TT_hihiss _{emitted radiation iemitted radiation i}ss _{known aknown a}ss _fluorefluoress_{cence and icence and i}ss _{characterized by itcharacterized by it}ss

inten

intenss_{ity aity a}ss _{a function of both time and wavelengtha function of both time and wavelength}.. SS_{ince thiince thi}ss _{information iinformation i}ss _{linked tolinked to}

the phy

the physs_{ical characteriical characteri}ss_ticticss _{of an individual molecular of an individual molecular} ss _pecie peciess_{, it provide, it provide}ss _{a powerfula powerful}

mean

meanss _{to perform chemical analyto perform chemical analy}ss_ees.s. _{By the obBy the ob}ss_{ervation of wavelength and time we canervation of wavelength and time we can}

detect, identify and quantify the chemical

detect, identify and quantify the chemicalss _pecie peciess_{within an aqueouwithin an aqueou}ss ss_{olutionolution}..

T

T_{he Lahe La}ss_er er --_{InducedInduced} FF_luoreluoress_{cence (LIcence (LI}FF_{) take) take}ss _{advantage of both time andadvantage of both time and}

wavelength information to inve

wavelength information to invess_{tigate the contamination of Btigate the contamination of B}TXTX _{compoundcompound}ss _inin ss_{oil andoil and}

water 

water .. TT_{he device providehe device provide}ss _{excitation uexcitation u}ss_{ing a paing a pa}ssss_{ively Qively Q}-s-s_{witched microlawitched microla}ss_{er pumpeder pumped}

 by fiber 

 by fiber --_{coupled near coupled near} --_{infrared diode lainfrared diode la}ss_{er and generateer and generate}ss ss_{hort pulhort pul}ss_eess _{of 2of 2}6666_{nm radiationnm radiation}

at a repetition rate near 10 k 

at a repetition rate near 10 k HH_zz.. TT_{he microchip lahe microchip la}ss_{er focuer focu}ss_{ing opticing optic}ss _{and collectionand collection} s

s_yyss_{tem are very compact and the entire atem are very compact and the entire a}ssss_{embly can be placed in a monitoring well or embly can be placed in a monitoring well or} 

contained within the

contained within the ss_{haft of a cone penetrometer haft of a cone penetrometer} .. TT_huhuss _{the UV radiation necethe UV radiation nece}ssss_{ary toary to}

excite fluore

excite fluoress_{cence in environmental pollutantcence in environmental pollutant}ss ss_{uch auch a}ss _gagass_{oline ioline i}ss_{generated at the pointgenerated at the point}

of contamination while the infrared diode pump la

of contamination while the infrared diode pump lass_{er remainer remain}ss _{above the groundabove the ground}.. TT_hihiss

configuration take

configuration takess _{advantage of the excellent tranadvantage of the excellent tran}ss_mimissss_{ion of infrared energy throughion of infrared energy through}

fiber optic

3.3.1 EXPERIMENTAL APPARATUS 3.3.1 EXPERIMENTAL APPARATUS

T

T_{he experimental apparatuhe experimental apparatu}ss _uuss_{ed to evaluate the performance of the LIed to evaluate the performance of the LI}FF _probeprobe

include

includess ss _{pectro pectro}ss_{copic hardware, a tecopic hardware, a te}ss_{t cell and a data acquit cell and a data acqui}ss_itionition ss_yyss_temtem..

Fig. 3.2 Schematic diagram of experimental apparatus Fig. 3.2 Schematic diagram of experimental apparatus

(Source: Sinfield. J.V .et.al, 200 (Source: Sinfield. J.V .et.al, 20077₎₎

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

 Dept Of Civil Engg:, M.C.E.T, Pathanamthitta 2121

A

A _{diode ladiode la}ss_{er pump attached to the microchip laer pump attached to the microchip la}ss_{er, mounted in the probeer, mounted in the probe}

iiss _{pumped by a 1W continuoupumped by a 1W continuou}ss _{wave atwave at} 88₀₀88_nmnm.. TT_{he UV thuhe UV thu}ss _{generated igenerated i}ss _focufocuss_{ed ontoed onto}

 probe¶

 probe¶ss ss_{apphire window through the excitation fiber apphire window through the excitation fiber} .. TT_hehe ss_{apphire window focuapphire window focu}ss_eess _thethe

UV radiation to the

UV radiation to the ss _{pecimen in the te pecimen in the te}ss_{t cellt cell}.. MM_{olecular fluoreolecular fluore}ss_{cence excited by the UVcence excited by the UV}

microchip la

microchip lass_{er er ii}ss _{imaged through probe¶imaged through probe¶}ss ss_{apphire window onto the tip of the returnapphire window onto the tip of the return}

fiber  fiber ..

T

T_{he output fiber ihe output fiber i}ss _focufocuss_{ed on the entranceed on the entrance} ss_{lit of a 1/lit of a 1/}88_mm ss_{canningcanning}

monochromator 

monochromator .. SS_{ilica beamilica beam}ss _{plitter mounted within the monochromator to direct a plitter mounted within the monochromator to direct a} ss_mallmall

fraction of light a

fraction of light ass _{trigger trigger} ss_{ignal to the trigger Pignal to the trigger P}MTMT _{and the reand the re}ss_{t t ii}ss _{directed on to thedirected on to the}

detector P

detector PMT.MT. TT_{he fahe fa}ss_{t photomultiplier tubet photomultiplier tube}ss_uuss_{ed to detect the intened to detect the inten}ss_itieitiess_{of the light areof the light are}

operated approximately at

operated approximately at 88_00V00V.. _{Both the PBoth the P}MTsMTs _{are connected to a 1are connected to a 1}.5.5 GHGH_{z digitalz digital} s

s_{torage otorage o}ss_cillocilloss_copecope.. _{It It ii}ss _uuss_{ed ed aa}ss _{an analogan analog}--_{to digital converter to acquire fluoreto digital converter to acquire fluore}ss_cencecence s

s_ignalignals.s. TT_{he he PP}MTMT _outputoutput ss_{ignal iignal i}ss _meameass_{ured acroured acro}ssss _aa 55_{00 loadload}.. AA _per per ss_{onal computer ional computer i}ss

u

uss_{ed to control the monochromator grating and the oed to control the monochromator grating and the o}ss_cillocilloss_copecope.. A

A ss_erieeriess _{of teof te}ss_ttss_{were performed to determine thewere performed to determine the} ss_enenss_or¶or¶ss ss_enenss_{itivity toitivity to}

B

BTXTX _{compoundcompound}ss _{and itand it}ss _timetime--_reress _pon ponss_ee.. EE_{ach teach te}ss_{t involved recording the timet involved recording the time}--_{dependentdependent}

fluore

fluoress_cencecencess _{pectrum (from 27 pectrum (from 27}55 _toto 3355_{0nm) of one of the B0nm) of one of the B}TXTX_{compoundcompound}ss_{at a particular at a particular} 

concentration in water 

concentration in water .. _UUss_{ing thiing thi}ss_{, profile wa, profile wa}ss_{plotted and theplotted and the}ss _{pectra from each te pectra from each te}ss_{t weret were}

analyzed to

analyzed to determine:determine: 1

1.. TT_{he total fluorehe total fluore}ss_cencecence ss_{ignal gathered from the teignal gathered from the te}ss_{t mediumt medium}-- _{by time and by time and}

wavelength integration wavelength integration 2

2.. TT_{he fluorehe fluore}ss_{cence lifetime of the compound cence lifetime of the compound inin}ss_{olutionolution}-- _{by time and emi by time and emi}ssss_ionion

wavelength integration wavelength integration

3

3.. TT_{he wavelength of the peak fluorehe wavelength of the peak fluore}ss_{cence emicence emi}ssss_ionion--_{the highethe highe}ss_{t intent inten}ss_{ity at anyity at any}

wavelength wavelength

4.

4. TT_{he peak fluorehe peak fluore}ss_{cence intencence inten}ss_ityity--_{the volume under wavelengththe volume under wavelength}--_timetime--_intenintenss_ityity

 profile  profile

T

3.3.2 ADVANTAGES AND DISADVANTAGES 3.3.2 ADVANTAGES AND DISADVANTAGES

3.3.2.1 Advantages 3.3.2.1 Advantages

1

1.. _{It iIt i}ss _{a very compact collectiona very compact collection}ss_yyss_temtem.. SS_{o it can be placed in a monitoring well or o it can be placed in a monitoring well or} 

within a cone penetrometer  within a cone penetrometer ..

2

2.. _LILIFF _{can be ucan be u}ss_{ed for the detection of contamination both in water aed for the detection of contamination both in water a}ss_{well awell a}ss_ininss_oiloil.. 3

3.. TT_{he intenhe inten}ss_{ity of fluoreity of fluore}ss_{cence icence i}ss _{a function of wavelength and time, which ia function of wavelength and time, which i}ss

linked to the phy

linked to the physs_{ical characteriical characteri}ss_ticticss _{of an individual molecular of an individual molecular} ss _pecie peciess_{, provide, provide}ss

a powerful mean

a powerful meanss _{to detect the contaminantto detect the contaminant}s.s. 4.

4. _{It haIt ha}ss _{the ability to detect the prethe ability to detect the pre}ss_{ence of a compound inence of a compound in}ss_{olution or recognize aolution or recognize a}

change in

change in ss_{tate, relative to background conditiontate, relative to background condition}s.s. SS_{o it helpo it help}ss _{in finding leak in finding leak} ss _inin

landfill

landfillss_yyss_temtemss_{or indicateor indicate}ss_{the prethe pre}ss_{ence of harmful agentence of harmful agent}ss_{in water in water} .. 5.

5. SS_{ince it iince it i}ss _popossss_{ible to detect, identify and quantify the contamination, it iible to detect, identify and quantify the contamination, it i}ss_eaeass_{y toy to} s

s_{elect the type and extent of treatment to be givenelect the type and extent of treatment to be given}..

3.3.2.2 Disadvantages 3.3.2.2 Disadvantages

1

1.. _{It It ii}ss _{very difficult to detect the prevery difficult to detect the pre}ss_{ence of Benzene in water ence of Benzene in water} .. AA_llss_oo EE_{thylbenzenethylbenzene}

cannot be detected at all cannot be detected at all..

2