2-Jul-08

Remediation of Sulfolane Impacted Groundwater – Characterization, Treatment and DisposalStacy Gibb, Jamie Fairles

7/2/20082

Outline

History of SulfolaneHistory of Impacted Groundwater at FacilityPiloting and Full Scale Treatment systemBasis of System DesignSystem Construction, Start up and OperationFuture Actions

7/2/20083

Sulfolane

C4H8O2S (Sulfolane molecular formula)Developed by Shell Oil in 1944Fully soluble in water with low volatility and low Henrys Law ConstantUsed in Sulfinol process along with DIPA and is a highly recoverable solventUsed to purify natural gas by removing acid gases and aromatics from hydrocarbon mixturesNow used in a wide variety of applications including polymers and electrical applications

7/2/20084

History of Sulfolane Remediation

Originally studies completed on biodegradation of Sulfolane in industrial wastewatersResearch studies were completed by University of Alberta in the mid 1990’s focusing on soil/groundwater remediationStoichiometry of Sulfolane oxidation under ideal conditions :C2H8O2S + 6.5O2 4CO2 + 3H2O + 2H+ + SO-4

Canadian Environmental Quality Guidelines for Sulfolane; Water and Soil (CCME 2006) provides the primary criteria for Sulfolane remediation

7/2/20085

History of Impacted Groundwater at the Facility

Sulfolane and DIPA were first detected in groundwater at the site in the 1980’sIn 1994 a detailed monitoring program was initiatedIn 1997 a five (5) year program was started to remove primary sources of Sulfolane and DIPAA regional Sulfolane monitoring program started in 1998 detected offsite SulfolaneBetween 1990-2000, 56 monitoring wells were installed to determine baseline concentrations

7/2/20086

History of Impacted Groundwater at the Facility

Treatability of Sulfolane-impacted groundwater was investigated in 2001-2002 focusing on:

– Groundwater recovery– Lab scale In-situ remediation– Lab scale biodegradability testing

Eight (8) recovery wells were installed in 2001-2002 in the capture zones2002-2003 a standalone pilot system was commissioned onsiteCapture Zone Modelling was completed in 2003-2004 for the plume delineation of the three different groundwater zones (A, B, and C)

7/2/20087

Zone B Plume Delineation

7/2/20088

Zone C Plume Delineation

7/2/20089

Piloting of Treatment System

Pilot treatment system was aerobic biological system with activated sludge and clarifierActivated sludge from the plant process wastewater treatment system was used for pilot system inoculationTreatment effective to 0.001 mg/LTreatment capacity 150m3/dayEffluent was sent to plant wastewater treatment systemTreatment system was susceptible to loss of suspended solidsPilot system was operated seasonally for 2 years

7/2/200810

Piloting of Treatment System Results

Pumping Location 2003 2004

East Boundary

Months of Operation 4 3

Volume Treated 3,700 m3 2,400 m3

Estimated Mass of Sulfolane Removed ≈ 28 Kg/month ≈ 15 Kg/month

South Boundary

Months of Operation 5 5

Volume Treated > 12,000 m3 > 12,000 m3

Estimated Mass of Sulfolane Removed ≈ 5 Kg/month ≈ 5 Kg/month

7/2/200811

Expanding to Full Scale Treatment System

Due to promising results in pilot stage, full scale and year-round treatment was feasibleDesign for full scale treatment system initiated in 2005Existing water treatment infrastructure at the site was available to be retrofitted for the processRecovery wells required upgrading to accommodate pumping all year round

7/2/200812

Full Scale Treatment System Design Criteria

Design for maximum flow rate of 400 m3/dDesigned to reduce Sulfolane by 99.99% (objective of below detectable levels in effluent)Clarifier Hydraulic Retention Time (HRT) is the size limiting constraint on systempH adjustment included based on groundwater chemistryChemical addition to aid in solids removal as requiredEffluent to be commingled with plant’s wastewater effluent

Design ParameterInfluent Value

Target Effluent Value Units

Flow Rate 400 400 m3/d

pH 8 7-7.5 -

Temperature 8 8-14 °C

BOD5 15 5 mg/L

COD 25 10 mg/L

Ammonia (NH3-N) <0.1 0.5 mg/L

Phosphorous <0.1 0.5 mg/L

Total Suspended Solids --- 25 mg/L

Sulfolane 8Non-detect mg/L

7/2/200813

System Design

Network of five (5) groundwater wells are tied into system (communication via radio link)Aerated biological system with clarifier and filter for final polishingSystem is fully automated, requires little operator input with alarms tied to plant control systemSystem is set up with spare pumps and blowers that alternate duty cycleComputer for human machine interface (HMI) and local control

7/2/200814

Full Scale Treatment Process

7/2/200815

System Construction

Space constraints and existing equipment limited equipment/pipe locationsExisting concrete tanks required upgrading to meet engineering standardsConstruction was scheduled to have minimal impact on plant operationsPipeline construction connecting wells required significant safety measures to avoid existing infrastructureSystem construction was completed with excellent safety record

7/2/200816

System Start up and Operation

System was inoculated with seed bacteria from the plant’s wastewater systemDuring commissioning, AENV required the system be shown to be operating properly prior to creek discharge through lab analysis for aquatic toxicity

7/2/200817

System Start up and Operation

Lab samples are taken bi-weekly to test for sulfolane removal and to confirm system meets discharge criteriaFacility lab takes bi-weekly samples to monitor health of the systemMaintenance performed by plant personnel as part of regular plant maintenanceSystem is automated and requires routine visits 2-3 times per week for visual inspection by plant personnel

7/2/200818

System Start up and Operation

Acid AdditionAcid addition is important to the system to decrease the Langelier Saturation Index (LSI)Negative LSI will dissolve CaCO3Positive LSI Scale can form and CaCO3 precipitation may occurLSI greater than +1.0 there is a higher potential scale will occur Water with a LSI of 1.0 is one pH unit above saturationReduction of pH from 7.8 –7.2 in the systems final effluent greatly reduced the potential for the water to scalePrior to acid addition after each pumping step there was subsequent increase in pH

6

6.5

7

7.5

8

8.5

9

9-Mar-07 28-Apr-07 17-Jun-07 6-Aug-07 25-Sep-07 14-Nov-07 3-Jan-08

Date

pH

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

pH Calculated LSI as CaCO3 Calculated LSI as Ca+

7/2/200819

System Start up and Operation –Health of Biomass

Direct correlation between Volatile Suspended Solids (VSS) concentration in bioreactor and sulfolane removal in effluentLoss of VSS in bioreactor resulted reduction of sulfolane removal5 -10% of the Total Suspended Solids (TSS) in the bioreactor are Volatile System maintenance accounted for loss of solids in September which resulted in increased sulfolane in the effluent

0

2

4

6

8

10

12

14

16

18

20

9-Mar-07 28-Apr-07 17-Jun-07 6-Aug-07 25-Sep-07 14-Nov-07 3-Jan-08

Date

Con

cent

ratio

n of

Sul

fola

ne m

g/L

0

200

400

600

800

1000

1200

1400

Con

cent

ratio

n of

Sol

ids

in m

g/L

Groundwater Influent Groundwater Effluent TSS VSS

7/2/200820

System Start up and Operation – 2007 Sulfolane Removal

Removal rates vary between months due to recovery well combinations (higher vs lower concentrations in wells)Commissioning in March to April resulted in inconsistent removal due to system instrumentation and communication issues In June the system was shutdown for evaluation of acid addition to reduce scaling potentialJuly to December the system operated as designed at a reduced flow for biomass health

Month Total Flow (m3) Removal (kg)

March 808.8 2.8

April 1715.2 4.2

May 3800.5 5.8

June 106.0 0.1

July 3773.1 26.2

August 3166.9 11.6

September 2106.5 24.4

October 4056.1 19.5

November 3860.5 16.9

December 3865.0 13.7

FLOW TOTAL 27258.6 125.2

7/2/200821

Future Actions

Additional monitoring and recovery wells to be installed Target higher concentrated groundwater around plant site will increase and stabilize biomass populationContinue pumping from plume boundaryPilot system has been relocated to another facility to apply technology elsewhere

7/2/200822

Acknowledgements

Randall Warren – Shell Energy CanadaCarol Elliott – Shell Energy CanadaRichard Ettenhofer – Shell Energy CanadaRyan Strom – WorleyParsonsRoy Hunt – WorleyParsons Sean Kelly – WorleyParsonsNorris Graham – WorleyParsons

7/2/200823

References

Canadian Council of Ministers of the Environment, 2006. Canadian Environmental Quality Guidelines for Sulfonlane: Water and Soil. Scientific Supporting Document.