Enhancement of Soil Aquifer Treatment to Improve the Quality of Recharge Water in the Llobregat River Delta Aquifer
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Enhancement of Soil Aquifer Treatment to Improve the Quality of Recharge Water in the Llobregat River Delta Aquifer. 1rst Annual Conference SCARCE Girona, 02.12.2010 1. INDEX 2) CONTEXT • Llobregat Delta Aquifer 6) IMPROVEMENT OF THE LOCAL • Infiltration Ponds HYDROGEOLOGICAL • Soil Aquifer Treatment (SAT) KNOWLEDGE • Biodegradation and REDOX • Emerging pollutants • Geological profiles • Pumping test 3) THE PROJECT • Tracer tests • Objectives • Characteristics 7) FUTURE WORK • Structure 4) SELECTION OF ORGANIC SUBSTRATE 8) CONCLUSIONS • Leaching tests • Column tests • Development of a numerical model 5) TEST SITE INSTRUMENTATION 2 2. CONTEXT: Llobregat Delta Aquifer Llobregat Delta is a strategic water resource to Barcelona metropolitan area supply: • 23 municipalities DWTPDWTP • 2.912.000 inhabitants ABRERA 5% ABRERA • Consumption: 200 hm3/yr 46% DWTPDWTP CARDEDEUCARDEDEU BARCELONA DWTPDWTP SANTSANT JOANJOAN DESPÍDESPÍ 37% DWTPDWTP 2% BESÒSBESÒS WELLSWELLS LLOBREGATLLOBREGAT AQUIFERAQUIFER 10% 3 2. CONTEXT: Infiltration ponds Low Llobregat Overexploitation of the main aquifer: Valley aquifer Castellbisbal • Decrease of water table Martorell Castellbisbal • Groundwater quality degradation 3.1 Main aquifer recharge techniques are: Sant Andreu Molins de Rei • River bed scarification (1) de la Barca Sant Feliu de Llobregat 1 •ASR wells (2) Pallejá Sant Joan Despí • Infiltration ponds (3) Cornella de Llobregat 3.2 Sant Vicenç • Hydraulic barrier (4) L’Hospitalet 2 3.3 Sant Boi de Llobregat El Prat de Llobregat Viladecans 4 Gava 5 Castelldefels Llobregat Mediterranean Sea Delta aquifer 4 2. CONTEXT: Experimental Site Decantation pond (4.000 m2) Infiltration pond (5.600 m2) Sant Vicenç dels Horts (Barcelona) experimental site 5 STATE OF THE ART 2. CONTEXT: Soil Aquifer Treatment Soil Aquifer Treatment (SAT): During recharge through the vadose zone and transport through the aquifer, water quality improvements occur that are described as Soil Aquifer Treatment (SAT), which offers the possibility of removal of dissolved organic matter by: – Biological processes: biodegradation – Physical and chemical processes: filtration, adsorption/desorption, cation exchange processes 6 2. CONTEXT: biodegradation and REDOX The degradation of pollutants occurs through microorganisms mediated biochemical reactions: Redox CH2O + O2 Æ CO2 + H2O Aerobic respiration potential - + CH2O + 0,8 NO3 + 0,8 H Æ CO2 + 0,4 N2 + 1,4 H2O Denitrification + 2+ CH2O + 2 MnO2(s) + 4 H Æ CO2 + 2 Mn + 3 H2O Mn oxides reduction + 2+ CH2O + 4 Fe(OH)3(s) + 8 H Æ CO2 + 4 Fe + 11 H2O Fe ox/hydrox reduction 2- - CH2O + 0,5 SO4 Æ CO2 + 0,5 S2 + H2O Sulphate reduction CH2O Æ 0,5 CO2 + 0,5 CH4 Methanogenesis Recalcitrant compounds: • Pesticides • Pharmaceuticals Biodegradation under specific REDOX state • Household products • Personal Care Products Organic substrate Æ widely applied for promoting biodegradation processes in groundwater remediation (REACTIVE BARRIERS) Why don’t use horizontal organic layers in infiltration basins for promoting REDOX zonation??? 7 2. CONTEXT: Emerging pollutants Trace organic contaminants are ubiquitous in water Emerging contaminants are often present in the effluent discharges of WWTPs after conventional tertiary treatments Impacts to aquatic life demonstrated, adverse impacts to public health far less certain: scientific community and end users are increasing their concern about these substances Detection methods have been improved, so they can be quantified in lower concentrations (ng/L - µg/L) Pesticides Drugs Estrogens Contrast media … 8 2. CONTEXT: Emerging pollutants ORGANIC DEGRADATION DEGRADATION PRODUCT PRODUCT COMPOUND (QUANTITATIVE) (QUALITATIVE) DICLOFENAC VV V IBUPROFEN x 15 COMPOUNDS V CARBAMAZEPINE x (QUANTITATIVE ANALYSIS) DRUGS GEMFIBROZIL xx + ATENOLOL xx 7 DEGRADATION SULFAMETOXAZOL xx PRODUCTS SIMAZINE V (QUALITATIVE x PESTICIDES ANALYSIS) V DIURON x V ESTROGENS ESTRONE x CONSTRAST IOPROMIDE V MEDIA x 9 3. THE PROJECT: Objectives • Demonstration of the application of reactive barrier technologies used in groundwater remediation for an innovative use: improvement of SAT efficiency during AR with reclaimed water or low quality surface water • Improvement of recharge water and groundwater quality at Sant Vicenç dels Horts site with an artificial system and passive treatment • Development of a modeling tool for predicting the evolution of the integrated system • Adaptation and transfer of results to other Aquifer Recharge (AR) sites 10 3. THE PROJECT: Characteristics Title: ENhancement of Soil Aquifer Treatment to Improve the quality of Recharge Water in the Llobregat River Delta Aquifer (ENSAT) Duration: 2,25 years (01/01/10 Æ 31/03/12) Coordinator: Partners: Stakeholders: Budget: Total Æ 1.240 k€ Funding Æ 50% 11 3. THE PROJECT: Structure A1 A4 EQUIPEMENT OF THE A7 SELECTION OF ORGANIC RECHARGE SITE FOR METHODOLOGY TO SUBSTRATE MONITORING ACTIVITIES TRANSFER TECHNOLOGY A2 A5 ASSESMENT OF THE A8 DEVELOPEMENT OF ORGANIC SUBSTRATE PROJECT MANAGEMENT NUMERICAL MODEL EFFICIENCY AND ITS IMPLACT ON GROUNDWATER QUALITY A3 A6 A9 ENGINYEERING ASPECTS AND EMERGING POLLUTANTS COMMUNICATION AND IMPLEMENTATION SURVAILANCE DISSEMINATION Laboratory Instrumentation Installation of Sampling and Interpretation and experimentation of the AR site the organic layer monitoring transfer technology 12 STATE OF THE ART 4. SELECTION OF ORGANIC SUBSTRATE 4.1. LEACHING TESTS - cheap: no cost / low cost Objective: Find proper substrates which will be - widely available (quantity, place) used in the column and field experiments through - highly effective as carbon source estimating the rate of releasing Dissolved Organic - easy handling Carbon (DOC) Organic substrate must be - safe and harmless - by-product / regenerated waste A B A = 1-week-old vegetation from garden and forest B = 15-day-old grass C1 = Grape skin with wood flakes C2 = Grape skin without wood flakes C1 C2 Dissolved Organic Carbon + (DOC) 5 L distilled Dissolved Oxygen (DO) water Alkalinity + pH time Eh 13 4. SELECTION OF ORGANIC SUBSTRATE 4.1. LEACHING TESTS SUBSTRATE SELECTION SUBSTRATE A SUBSTRATE B SUBSTRATE C “K” VALUE (REACTIVITY) ↑↑↑↑↑↑ SUPPLY EASY DIFFICULT SEASONAL IMPACT IN THE LOW HIGHT HIGHT AQUIFER QUALITY Visit to the supplier compost plant (Castellcir, Barcelona) 14 4. SELECTION OF ORGANIC SUBSTRATE 4.2. COLUMN EXPERIMENTS Objective: simulating real conditions of the infiltration basin of Sant Vicenç dels Horts recharge site. Substrate employed in the reactive column Recharge water: River Llobregat water Column 1Æ mix of sieved soil (diameter 2-5- mm + selected organic compost) Column 2 Æ only sieved soil 15 4. SELECTION OF ORGANIC SUBSTRATE 4.2. COLUMN EXPERIMENTS Sampling points: Dissolved Organic Carbon (DOC) 50 cm, 25 cm and 2 cm Dissolved Inorganic Carbon (DIC) from the bottom + supernant Dissolved Oxygen (DO) Monitored time: pH, Eh 32 days (undergoing…) Conclusions of column experiments: - Selected organic substrate is an efficient source for DOC to recharge water. - 50 cm of reactive material is able to still supply up to 60 mg/L of DOC after one month functioning. - Organic layer can also provide other properties as adsorption to improve de degradation of organic pollutants. DOC in the reactive column 16 4. SELECTION OF ORGANIC SUBSTRATE 4.3. NUMERICAL MODEL 400 350 Objective: Forecast the chemical behaviour of 300 recharge water through “enhanced SAT” 250 2 main processes are involved: 200 150 Outlet DOC = DOC (mg/L) initial DOC (20 mg/L) Dissolution of the solid to DOC (CH2O) 100 50 CH2O (s) ↔ CH2O (aq) 0 Biogenic oxidation of a fraction of the DOC at 0 102030405060708090100 the expense of the dissolved oxygen: time (days) - + Forecast of the numerical model: CH2O (aq) + O2 ↔ HCO3 + H • In 90 days organic layer will be stabilized (no extra DOC in water Æ field experimentation 9 months. • Later Æ sorption properties will continue acting during the experiment 17 5. TEST SITE INSTRUMENTATION 5.1. INSTRUMENTATION OF THE SATURATED ZONE - piezometers in the infiltration pond - piezometers downstream - well (350 mm diameter): - pumping tests -tracer tests - observation well - Dataloggers (CDT’s and DT’s) in the new observation points 5.2. INSTRUMENTATION OF THE UNSATURATED ZONE - Construction of a new island (C): - porous cups (1m; 2m) - temperature sensors (1m) - tensiometers (1m; 2m; 3m) - humidity sensor (1m) 18 5. TEST SITE INSTRUMENTATION 5.3. IMPROVEMENT OF THE NETWORK FOR MONITORING 19 6. IMPROVEMENT OF THE LOCAL HYDROGEOLOGICAL KNOWLEDGE 6.1. GEOLOGICAL PROFILES 6.2. PUMPING TEST - Flow: 104.000 L/h - Total duration: 48 hours - Recovery: 24 hours 20 6. IMPROVEMENT OF THE LOCAL HYDROGEOLOGICAL KNOWLEDGE 6.3. TRACER TESTS Objectives: Determination of the hydraulic properties at local scale: - Hydraulic conductivity - Transmissivity Method: -Forced gradient tracer test (October 2010) -9 different tracers used - Inorganic anions -Dyes - Instantaneous injection (short duration and small well storage) 21 7. FUTURE WORK According to project proposal, next steps will be: - Blank infiltration period (12/2010 – 01/2011): 2 sampling campaigns - Design of organic layer - Installation of the organic layer in the surface of the pond (02/2011) - 9 months of infiltration, monitoring and sampling (03/2011 – 11/2011) - Development of a user-friendly tool to apply the numerical model (2011) - Transfer the knowledge to other AR sites (2011) Laboratory Instrumentation Installation of Sampling and Interpretation and experimentation of the AR site the organic layer monitoring transfer technology 22 8. CONCLUSIONS - Llobregat Aquifer Æ strategic resource in Barcelona -The ENSAT project aims to improve SAT with an innovative technology - Some actions of ENSAT have been carried out according to the project: - Selection of the organic substrate (compost) - Instrumentation of the test site (Sant Vicenç dels Horts, Barcelona) - Improvement of the local hydrogeological information - First results are optimistic: -selected substrate will give an extra DOC contribution - REDOX zonation will be stimulated -Expected degradation of some recalcitrant organic compounds 23 THANK YOU!!! 24.