Urban gasoline stations: new techniques for early leak detection from USTs and removal of low concentration pollutants from groundwater

Transcription

1 1 NATO/CCMS Pilot Study Meeting Athens June 4-7, 2006 Urban gasoline stations: new techniques for early leak detection from 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, MONTEROTONDO (Roma), Italy

2 OUTLINE 2 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

3 Eni Refining & Marketing Division 3 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.

4 Scope of the work 4 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

5 SOIL ALERT 5 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

6 SOIL ALERT: Leak detection of USTs 6 Solar panel Data logger Volt meter S5 S4 S1 S2 S3

7 7 SOIL ALERT: Leak detection of USTs External part of probe Comparison of SOIL ALERT Probe and PID signals ,5-3,5-3 -3,5 Log (conc. PID) -4-4,5-4 -4,5 Log (1/Rs) ,5-6 -5,5-6,5 Log(1/Rs) Log(conc.PID) Same day measurements on 37 probes

8 Calibration of gas sensors 8 y = 0,3887Ln(x) - 0,6743 3,0 Output (V) 2,5 2,0 1,5 1,0 0,5 Volts ppmv 0,6 25 1, , , , n-octane concentration (ppmv)

9 SOIL ALERT: Leak detection of USTs Monitoring campaign at an Agip service station in central Italy 15 days monitoring /7/ /7/ /7/ /7/ /7/ /7/ /7/ /8/ /8/ /8/ /8/ /8/ /8/ /8/ /8/ Vout (V) Temp. ( C) Sonda 1 Sonda 2 Sonda 3 Sonda 4 Sonda 5 T aria T suolo

10 SOIL ALERT: Leak detection of USTs 10 A field simulation was carried out by spilling small amounts of gasoline and diesel 30 days monitoring 0,45 0,4 Gasoline leak simulation Vout (V) 0,35 0,3 0,25 0,2 0,15 0,1 0, /7 25/7 27/7 29/7 31/7 2/8 4/8 6/8 8/8 10/8 12/8 14/8 16/8 18/8 20/8 22/8 24/8 26/8 Gasoline spill start Sonda 1 Sonda 2 Sonda 3 Sonda 4 Sonda 5

11 SOIL ALERT: Leak detection of USTs 80 days monitoring Simulazione perdita di gasolio Diesel leak simulation 1.00E E-01 Diesel spill start Diesel leak detection 8.00E V 7.00E E E E E-01 sonda1 sonda2 sonda3 sonda4 sonda5 11 Vout (V) 2.00E E E+00 10/3/ /3/ /3/ /3/ /3/ /4/ /4/ /4/ /4/ /4/ /4/ /5/ /5/ /5/ /5/ /5/ /5/ /6/ /6/

12 SOIL ALERT: Leak detection of USTs 11 day monitoring at a dismissed service station Misure (t=30 min) Media Mobile (t=24 h) Soglia di Preallarme Soglia di Allarme V Genova Pegli dal 28/11/2004 al 9/12/ Vout 1.0 V Time

13 SOIL ALERT: Leak detection of USTs 1 year monitoring V 0.5 V 3 months 0.5 V 6 months 12 months

14 SOIL ALERT: Advantages and limitations Sensor output is an electrical signal, easily manageable for automatic and continuous remote control Large HC concentration range ( 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

15 Groundwater remediation 15 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 Groundwater Pump & treat

16 Adsorption: Granular Activated Carbon (GAC) 16 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

17 EniTecnologie EN-Z-LITE approach 17 EN-Z-LITE (Enitecnologie US Patent ) 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

18 Pump & Treat: : EN-Z-LITE 18 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

19 19 Laboratory Simulation Apparatus 200 ml columns 2 L column

20 EN-Z-LITE application: high concentration of MtBE and BTEX GC-MS inlet of simulation apparatus Compound benzene toluene ethylbenzene o-xylene p-xylene MtBE salt as NaCl mg/l >15 g/l 20

21 EN-Z-LITE application: high concentration of MtBE and BTEX GC-MS outlet of simulation apparatus 21 MtBE and aromatics (BTEX) outlet concentrations < 1 ppb

22 EN-Z-LITE pilot plant Mobile unit with 4 x 75 kg, water flux of ~ 1m3/h, trucked to field sites for differently contaminated waters 22

23 Full scale application: Agip service station 23 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

24 Full scale application: operating conditions 24 Remediation plant dimensions GAC pretreatment vessels: EN-Z-LITE vessels: Water flow: GAC replacement: Zeolite replacement: 4 x 1300 kg 4 x 350 kg 17 m 3 /h (max) ~ 2 tons/month ~ 100 kg/month Costs Water treatment total 0.85 Euro/m 3 of treated water

25 Full scale application: results 25 Groundwater decontamination figures (ppb) Inlet EN-Z-LITE outlet Controlling authority TPH < 1 10 MtBE < BTEX < 1 Benzene 1 Ethyl-benzene 50 Toluene 15 p-xylene 10

26 Full scale application: results 26 Kg/day Groundwater decontamination Removed hydrocarbons vs. time TPH MtBE Benzene 1,8 1,6 1,4 1,2 1,0 0,8 0,6 0,4 0,2 0, days EN-Z-LITE provides a technological improvement since it allows more effective removal of contaminants

27 SOIL ALERT and EN-Z-LITE: Future development 27 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

28 SOIL ALERT: tests in water 28 Laboratory tests in water containing toluene from 25 to 100 ppb 0,20 Volt (Vout) 0,16 0,12 0,08 25 ppb 75 ppb 50 ppb 100 ppb 0,04 0, Time (min)

29 SOIL ALERT: field tests in saturated soil 29 continuous measurements for 80 days ~ 400 ppb TPH 1,20 1,00 Volt(Vout) 0,80 0,60 0,40 0,20 0, days

30 Development of the combined SOIL ALERT and EN-Z-LITE remediation system 30 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

31 Acknowledgements 31 This presentation was made possible thanks to the dedicated work of: Adriano Bernardi Umberto Cova Fabio Fabiani Gianni Grillo Lucio De Angelis Vincenzo Mancini Raffaello Sisto Rodolfo Vignola Vittorio Vittori