Optimization of Engineered Injection and Extraction for In Situ Remediation of Sorbing Groundwater Contaminants

Optimization of Engineered Injection and Extraction for In Situ Remediation of Sorbing Groundwater ContaminantsJohn P. BrodtDr. Roseanna M. NeupauerAugust 8, 20132013 REU Summer Research ProjectIn Situ Remediation

Contaminant Plume highest concentrationimages accessed 7/30/2013 Left: http://dec.alaska.gov/spar/csp/images/fairbanks/gaffney_vi_map.jpgRight: http://www.regenesis.com/images/products/chemical-oxidation.jpgEngineered Injection and Extraction(EIE)-Initial Setup

WellsContaminant PlumeTreatment SolutionParticle Positionr=radial distance from wellQ=flow ratet=timeb=aquifer thicknessn=porosity

EIE Reaction for Aqueous Contaminant

Base CaseTreatment SolutionAqueous ContaminantReaction Product- Piscopo et al. (2013)

EIE Reaction for Aqueous Contaminant

Base CaseTreatment SolutionAqueous ContaminantReaction Product- Piscopo et al. (2013)

Strategy for Aqueous ContaminantsStretch and fold treatment solutionElongate interface between treatment solution and contaminant plume60%Sorbing Contaminants=sorption rate constant (1/T)Kd=partition constant (L/kg)C=contaminant concentration in aqueous phase (g/L)Cs=contaminant concentration in sorbed phase (g/kg)EIE Reaction for Sorbing Contaminants

Sorbed ContaminantAqueous ContaminantTreatment SolutionReaction ProductBase Case- Webber (2012)

EIE Reaction for Sorbing Contaminants

Sorbed ContaminantAqueous ContaminantTreatment SolutionReaction ProductStrategy for Sorbed ContaminantsPass Treatment solution over sorbed contaminants because sorbed contaminants are stationary

84%- Webber (2012)Research ObjectivesOptimize EIE for sorbing contaminants using a genetic algorithm for instantaneous reaction for a range of parameter values

Optimize EIE for sorbing contaminants using a genetic algorithm for rate-limited reaction for a range of parameter values

Find similarities in the different optimum string sequencesGenetic Algorithm (GA)Initial PopulationGA randomly selects 700 strings for first generationFitness Rankingdetermines each strings fitness (mass reacted) then ranks the individualsReproductionElite count-no alterationCross Bred- genes of two strings are crossed over at a single pointMutation- random changes to randomly selected genesOptimum StringThe string with the highest fitness after final generationGA ParametersFeasible Population = 1000 stringsElite Count = 70 stringsCrossover Fraction = 0.8Mutation Fraction = 0.2Constraints:1. Zero net fluid injected or extracted from the aquifer.

2. No particles can leave the manageable boundaries.

3. The sequence cannot surpass the determined ceiling for mass extracted from the wells.Optimization for Instantaneous Reaction using the 4 outer WellsOptimum String (4 wells) Instantaneous Reaction, Slow Sorption

Sorbed ContaminantTreatment SolutionAqueous ContaminantReaction ProductR=2.65=0.01(1/T)Optimum String (4 wells) Instantaneous Reaction, Slow Sorption

Sorbed ContaminantTreatment SolutionAqueous ContaminantReaction Product

90%Key Feature Step 9:The injection of clean water into the East well pushes the treatment radially outward for increased degradationR=2.65=0.01(1/T)Optimum String (4 wells) Instantaneous Reaction, Fast Sorption

Sorbed ContaminantTreatment SolutionAqueous ContaminantReaction ProductR=2.65=100(1/T)Optimum String (4 wells) Instantaneous Reaction, Fast Sorption

Sorbed ContaminantTreatment SolutionAqueous ContaminantReaction Product

98%Key Feature Step 8:The extraction from the South well folds the treatment solution after it had been spread out in the first 7 stepsR=2.65=100(1/T)GA Optimum Strings (4 Wells) for Range of Parameters (Kd,)Sorption rate constant, (1/T)Retardation Coefficient, R (-)Base Case SequenceGA Best String for 4 WellsContaminant Reacted (g)0.012.654929 (84%)5300 (90%)0.12.654922 (84%)5300 (90%)12.655685 (97%)5749 (98%)102.655784 (98%)5830 (99%)1002.655805 (99%)5790 (98%)0.0124694 (80%)4700 (80%)0.0155260 (89%)5367 (91%)0.01105403 (92%)5570 (95%)GA Optimum String Similarity Stretch and Fold with Sorbed Particle Contact

R=2.65, =0.1(1/T)

R=2.65, =1(1/T)

R=2.65, =10(1/T)

R=2.65, =100(1/TGA Optimum String Similarity Stretch and Fold with Sorbed Particle Contact

R=2.65, =0.1(1/T)R=2.65, =10

First 8 Steps of base case EIE sequence- Mays and Neupauer (2012)Optimization for Instantaneous Reaction using 5 WellsThe string creation function is allowed to use the center well in the EIE sequenceOptimum String (5 wells) Instantaneous Reaction, Slow Sorption

Sorbed ContaminantTreatment SolutionAqueous ContaminantReaction ProductR=2.65=0.01(1/T)Optimum String (5 wells) Instantaneous Reaction, Slow Sorption

Sorbed ContaminantTreatment SolutionAqueous ContaminantReaction ProductR=2.65=0.01(1/T)

95%Key Feature Use of Center Well:The center well efficiently pushes the treatment over the sorbed particles and into the aqueous contaminantOptimum String (5 wells) Instantaneous Reaction, Fast Sorption

Sorbed ContaminantTreatment SolutionAqueous ContaminantReaction ProductR=2.65=100(1/T)Optimum String (5 wells) Instantaneous Reaction, Fast Sorption

Sorbed ContaminantTreatment SolutionAqueous ContaminantReaction ProductR=2.65=100

100%Key Feature Step 9:The large injection rate in step 9 allows the treatment solution to overpass the entire contaminant plumeGA Optimum Strings (4 & 5 Wells) for Range of Parameters (Kd,)Sorption rate constant, (T-1) Retardation Coefficient, R(-)Base Case SequenceGA Best String for 4 WellsGA Best String for 5 WellsContaminant Reacted (g)0.012.654929 (84%)5300 (90%)5600 (95%)0.12.654922 (84%)5300 (90%)5878 (100%)12.655685 (97%)5749 (98%)5884 (100%)102.655784 (98%)5830 (99%)5884 (100%)1002.655805 (99%)5790 (98%)5884 (100%)0.0124694 (80%)4700 (80%)5726 (97%)0.0155260 (89%)5367 (91%)5852 (100%)0.01105403 (92%)5570 (94%)5884 (100%)GA Optimum String Similarity Alternating between Center Well and Outer Wells

R=5, =0.01(1/T)R=2.65, =1(1/T)

R=10, =0.01(1/T)

R=2.65, =10(1/T)Optimization for Rate-Limited Reaction using 5 WellsChemical Kinetics are incorporated into the modelOptimum String (5 wells) Slow Reaction, Slow Sorption

Sorbed ContaminantTreatment SolutionAqueous ContaminantReaction ProductR=2.65=0.1(1/T)Ka=2e-6(g/L/day)Ks=2e-7(L/g/day)R=2.65=0.1(1/T)Ka=2e-6(g/L/day)Ks=2e-7(L/g/day)Optimum String (5 wells) Slow Reaction, Slow Sorption

Sorbed ContaminantTreatment SolutionAqueous ContaminantReaction Product

30%Optimum String (5 wells) Slow Reaction, Fast Sorption

Sorbed ContaminantTreatment SolutionAqueous ContaminantReaction ProductR=2.65=1000(1/T)Ka=2e-6(g/L/day)Ks=2e-7(L/g/day)R=2.65=1000(1/T)Ka=2e-6(g/L/day)Ks=2e-7(L/g/day)Optimum String (5 wells) Slow Reaction, Fast Sorption

Sorbed ContaminantTreatment SolutionAqueous ContaminantReaction Product

33%GA Slow Optimum Strings (5 Wells) for Range of Parameters (Kd,)Sorption rate constant, (T-1)Retardation Coefficient, R (-)Aqueous Reaction Rate Constant, Ka (g*L-1*day-1)Sorbed Reaction Rate Constant, Ks (L*g-1*day-1)Base Case SequenceGA Best String for 5 WellsContaminant Reacted (g)0.12.652*10-62*10-7955 (16%)1765 (30%)12.652*10-62*10-71120 (19%)1959 (33%)102.652*10-62*10-71121 (19%)1835 (31%)1002.652*10-62*10-71125 (19%)1924 (33%)10002.652*10-62*10-71126 (19%)1977 (34%)0.122*10-62*10-7993 (17%)1919 (33%)0.152*10-62*10-7814 (14%)1518 (26%)0.1102*10-62*10-7623 (11%)1162 (20%)GA Slow Optimum Strings (5 Wells) for Range of Parameters (Ka,Ks)Sorption rate constant, (T-1) Retardation Coefficient, R (-)Aqueous Reaction Rate Constant, Ka (g*L-1*day-1)Sorbed Reaction Rate Constant, Ks (L*g-1*day-1)Base Case SequenceGA Best String for 5 WellsContaminant Reacted (g)0.12.652*10-62*10-7950 (16%)1765 (30%)0.12.652*10-52*10-63359 (57%)4875 (83%)0.12.652*10-42*10-54736 (81%)5835 (99%)0.12.652*10-32*10-44859 (83%)5881 (100%)0.12.652*10-22*10-34857 (83%)5789 (98%)GA Slow Optimum String Similarity Pushing treatment solution into the radial contaminant plume

R=2.65, =100, Ka=2e-6, Ks=2e-7

R=10, =0.1, Ka=2e-6, Ks=2e-7R=5, =0.1, Ka=2e-6, Ks=2e-7

R=2.65, =10, Ka=2e-6, Ks=2e-7GA Slow Optimum String Similarity smaller flow rates for slower reaction ratesR=2.65, =0.1, Ka=2e-2, Ks=2e-3R=2.65, =0.1, Ka=2e-3, Ks=2e-4R=2.65, =0.1, Ka=2e-5, Ks=2e-6R=2.65, =0.1, Ka=2e-6, Ks=2e-7

Conclusion1. GA improved the degradation from the EIE sequence by6% for fast reaction with 4 wells11% for fast reaction with 5 wells14% for slow reaction with 5 wells

2. Similarities in optimum stringsStretch and fold while passing over sorbed contaminant Alternating between center well and outer wellsPlacing treatment inside contaminant plumeSmaller injection and extraction rates for slower reaction rates Future WorkOptimization of EIE for heterogenous aquifers