Urban Gasoline Stations: New Techniques for Early Leak Detection ...
Transcript of Urban Gasoline Stations: New Techniques for Early Leak Detection ...
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NATO/CCMS Pilot Study Meeting – Athens – June 4-7, 2006
Urban gasoline stations: new techniques for early leak detectionfrom USTs and removal of low concentration pollutants from
groundwater
Renzo Boni, Rosario Pappa and Salvatore Contarini
Environmental Technology Research Centre (CEAMB)EniTecnologie SpA, Via Ramarini 32, 00016 MONTEROTONDO (Roma), Italy
e-mail: [email protected]
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OUTLINEOUTLINE
• Activities in support to Eni Refining & Marketing Division o Environmental monitoring at Service Stations
• Hydrocarbon leak detection in soils (SOIL ALERT) o Principles and main characteristics o Application to USTs (Underground Storage Tanks)
• Groundwater remediation by Pump & Treat (EN-Z-LITE)o Laboratory tests o Pilot plant o Full scale application
• Future activities and developments
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Eni Refining & Marketing DivisionEni Refining & Marketing Division
Fuel retail leader in Italy with ~ 5,000 Agip service stations.Reorganization of the distribution network, ~ 1000 small size urban area service stations ceded or removed. Enitecnologie involved in subsoil quality assessment and, where necessary, in remediation and environmental restoration actions.
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Scope of the workScope of the work
Development of a combined monitoring – remediation system capable to provide early warning for hydrocarbon leaking and effective groundwater treatment
Two Enitecnologie patents:
1. SOIL ALERT: a leak detector based on a resistive gas sensor
2. EN-Z-LITE: an adsorbent for effective groundwater removal of hydrocarbons, including BTEX and MtBE, associated to Pump & Treat technology
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SOIL ALERTSOIL ALERT
• SOIL ALERT is an alarm system for tank leakage control.
• It consists of a probe for interstitial gas detection in subsoil.
• The probe contains two sensors, one at the micro-holed bottom tip
and one at the top for aboveground air referencing.
• Can take continuous measurements, without use of extraction
systems and chemical analysis.
• ATEX explosion proof certification (EEX d II B T5) allows for use in
hazardous zones.
• Applications:
• Service stations and aboveground storage tank fields (AST)
• Remediation monitoring
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SOIL ALERT:SOIL ALERT: LeakLeak detection ofdetection of USTsUSTs
S1
S2
S3
S4S5
Volt meter
Data logger
Solar panel
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SOIL ALERT: Leak detection of USTsSOIL ALERT: Leak detection of USTs
External part of probe
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-5
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Log
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s)
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Log
(con
c. P
ID)
Log(1/Rs) Log(conc.PID)
Comparison of SOIL ALERT Probe and PID signals
Same day measurements on 37 probes
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Calibration of gas sensorsCalibration of gas sensors
y = 0,3887Ln(x) - 0,6743
0,0
0,5
1,0
1,5
2,0
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3,0
10 100 1000 10000 n-octane concentration (ppmV)
Out
put
(V)
Volts ppmV0,6 251,1 1001,7 4002,2 1600
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SOIL ALERT: Leak detection of USTsSOIL ALERT: Leak detection of USTs
• Monitoring campaign at an Agip service station in central Italy
15 days monitoring
0
0.05
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0.15
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(V)
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Tem
p. (°
C)
Sonda 1 Sonda 2 Sonda 3 Sonda 4 Sonda 5 T aria T suolo
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SOIL ALERT: Leak detection of USTsSOIL ALERT: Leak detection of USTs
• A field simulation was carried out by spilling small amounts of gasoline and diesel
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/7
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Gasoline leak simulation
Gasoline spill start
30 days monitoring
Simulazione perdita di gasolio
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SOIL ALERT: Leak detection of USTsSOIL ALERT: Leak detection of USTs
80 days monitoring
Diesel leak simulation 1.00E+00
Diesel leak detection
Diesel spill start
9.00E-01
8.00E-01 0.8 V 7.00E-01
sonda1 sonda2 sonda3 sonda4 sonda5
Vout
(V) 6.00E-01
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Genova Pegli dal 28/11/2004 al 9/12/2004
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SOIL ALERT:SOIL ALERT: LeakLeak detection ofdetection of USTsUSTs
11 day monitoring at a dismissed service stationMisure (t=30 min) Media Mobile (t=24 h) Soglia di Preallarme Soglia di Allarme
1600
1550
1.5 V 1500
1450
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V out 1300
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SOIL ALERT:SOIL ALERT: LeakLeak detection ofdetection of USTsUSTs
0.5 V
1 year monitoring1 year monitoring
3 months
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• Sensor output is an electrical signal, easily manageable for automatic and continuous remote control
• Large HC concentration range (10 - 5000 ppmV)
• Leak detection is fast compared to normal monitoring systems
• Low selectivity: these sensors respond, although to a different extent, to many reducing gases
• Signal fluctuates with changes in water table level
• Signal saturates in severely contaminated soils
• Require soil perforation for positioning
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• Sensor output is an electrical signal, easily manageable for automatic and continuous remote control
• Large HC concentration range (10 - 5000 ppmV)
• Leak detection is fast compared to normal monitoring systems
• Low selectivity: these sensors respond, although to a different extent, to many reducing gases
• Signal fluctuates with changes in water table level
• Signal saturates in severely contaminated soils
• Require soil perforation for positioning
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SOIL ALERT: Advantages and limitationsSOIL ALERT: Advantages and limitations
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Groundwater remediationGroundwater remediation
Pump & Treat is the most common form of groundwater remediation. It is often associated with treatment technologies such as Air Stripping or Adsorption.
In adsorption systems, granular activated carbon (GAC) is mainly used as sorbent material
Extraction well Tank Recovered
Pump & treat Groundwater
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Adsorption: Granular Activated Carbon (GAC)Adsorption: Granular Activated Carbon (GAC)
With GAC, organic molecules as well as certain metal and inorganic ions are attracted and adsorbed in the porosity of the sorbent
Limitations and Concerns
GAC not efficient with small organic molecules and water soluble contaminants like MtBE
If humic acids are present GAC adsorption capacity is rapidly decreased
If treated water has high salinity (eg. marine coastal sites), GAC regeneration and recycling becomes very difficult or not applicable
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EniTecnologieEniTecnologie ENEN--ZZ--LITE approachLITE approach
EN-Z-LITE (Enitecnologie US Patent 20040206705) for the removal of groundwater contaminants based on synthetic zeolites
Advantages of zeolites used for water treatment:
1. selectivity (based on physical-chemical affinities of
adsorbate and adsorbent)
2. good adsorption capacity (up to 15%)
3. higher efficacy towards MtBE
4. easy regeneration by thermal desorption
5. no effects of salts and interfering compounds such as humic
acids and inorganic ions
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PumpPump && TreatTreat: EN: EN--ZZ--LITELITE
Successfully proven applications
Simulation apparatus operating with sampled groundwater:• different hydrocarbon contaminants: chlorinated,
aromatic hydrocarbons (BTEX), MtBE, etc. at high concentration
Mobile pilot scale plant: • Field tested for various kinds of contaminants
Full scale plant at an Agip Service Station • Automotive fuels (gasoline, diesel) and MtBE
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GCGC--MS inlet of simulation apparatusMS inlet of simulation apparatus
1.3o-xylene
1.5ethylbenzene
2.9p-xylene
>15 g/Lsalt as NaCl
mg/LCompound
17.9MtBE
0.5toluene
2.8benzene
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GCGC--MS outlet of simulation apparatusMS outlet of simulation apparatus
MtBE and aromatics (BTEX) outlet concentrations < 1 ppbMtBE and aromatics (BTEX) outlet concentrations < 1 ppb
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ENEN--ZZ--LITE pilot plantLITE pilot plant
Mobile unit with 4 x 75 kg, water flux of ~ 1m3/h,trucked to field sites for differently contaminated waters
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Full scale application: Agip service stationFull scale application: Agip service station
Pump and Treat system using GAC and EN-Z-LITE to reduce outlet TPH, BTEX and MtBE concentration below the limit imposed by controlling authority
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Full scale application: operating conditionsFull scale application: operating conditions
Remediation plant dimensions
GAC pretreatment vessels: 4 x 1300 kg EN-Z-LITE vessels: 4 x 350 kg Water flow: 17 m3/h (max)
GAC replacement: ~ 2 tons/month
Zeolite replacement: ~ 100 kg/month
Costs
Water treatment total 0.85 Euro/m3 of treated water
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Full scale application: resultsFull scale application: results
Groundwater decontamination figures (ppb)
Inlet EN-Z-LITE outlet
Controlling authority
TPH 500 – 9000 < 1 ≤ 10
MtBE 500 - 3000 < 10 ≤ 10
BTEX 0 - 900 < 1
Benzene ≤ 1 Ethyl-benzene ≤ 50 Toluene ≤ 15 p-Xylene ≤ 10
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Full scale application: resultsFull scale application: results
Groundwater decontamination Removed hydrocarbons vs. time
TPH MtBE Benzene K
g/da
y
1,8
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EN-Z-LITE provides a technological improvement since it allows
more effective removal of contaminants
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SOIL ALERT and ENSOIL ALERT and EN--ZZ--LITE: Future developmentLITE: Future development
SOIL ALERT can be used in water media also
Upgrade by means of a protective polymeric membrane in the probe micro-holed section, selectively permeable to contaminant vapors
Benefits:
1. Measurements in water
2. Measurements in saturated zone
Future development:
SOIL ALERT sensor switches for the EN-Z-LITE groundwater remediation system
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SOIL ALERT: tests in waterSOIL ALERT: tests in water
Laboratory tests in water containing toluene from 25 to 100 ppb
Volt
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t)
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0,08
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Time (min)
25 ppb
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100 ppb
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SOIL ALERT: field tests in saturated soilSOIL ALERT: field tests in saturated soil
continuous measurements for 80 days
0,00
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1,00
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days
Volt(
Vout
) ~ 400 ppb TPH
30 Development of the combined SOIL ALERTDevelopment of the combined SOIL ALERT and ENand EN--ZZ--LITE remediation systemLITE remediation system
SOIL ALERT will be applied to continuous monitoring of groundwater remediation plants. Placed on vessels outlets, it can provide better timing for exhaust adsorbent replacement