Enhanced bioremediation of gasoline contaminated groundwater in Finland by injection of humic acids

Transcription

1 In situ workshop, Stockholm , Pirjo Tuomi Enhanced bioremediation of gasoline contaminated groundwater in Finland by injection of humic acids

2 Enhanced Natural Attenuation Most organic contaminants serve as suitable electron donors and are abundant following a release The concentration of suitable electron acceptors in groundwater generally limits the rate of hydrocarbon degradation electron donor organic carbon electron transfer electron acceptor O 2 NO 3 Fe 3+ SO 4 CO 2 CO 2 Bacterial Cell H 2 O N 2 Fe 2+ H 2 S CH 4

3 Enhanced Natural Attenuation Groundwater contaminated with organic contaminants Electron acceptors used in contaminant degradation vary with time and distance downgradient from source Identify the primary mechanism of contaminant degradation and enhance that process not change Methanogenesis Sulfate Reduction Iron Reduction Manganese Reduction Denitrification Aerobic Degradation

4 Case LUST site, vadose zone excavated, residual concentrations in smear zone Plume delineated and stabile (not expanding, nor shrinking) Slow ground water flow, confined aquifer

5 Case No health risc No environmental risc (plume not expanding) Site at classified groundwater area environmental authority required remediation Studies on site geochemistry: electron acceptors, redox electron donor organic carbon electron transfer electron acceptor O 2 NO 3 Fe 3+ SO 4 CO 2 CO 2 Bacterial Cell H 2 O N 2 Fe 2+ H 2 S CH 4

6 TVOC, mg/l TVOC, mg/l Case GW naturally low in oxygen Geochem.: biodegradation takes place mainly by means of iron reduction O 2 and redox NO 3 Dissolved iron (filtered total iron) SO 4 (no trend) 10,000 10,000 1,000 1,000 0,100 0,100 0,010 0,010 0,001 0,001 0,0 10,0 20,0 30,0 0,00 2,00 4,00 6,00 8,00 O2, Happikylläisyys, % of saturation % Liuennut Dissolved rauta, iron, mg/l mg/l

7 Case Options: MNA P&T ENA Does take place at the site, but because the plume was not shrinking it could not be estimated how long it would take to site closure Pressure from the authority to active remediation ENA more cost efficient Enhancement of iron reduction based biodegradation Target: reduction of contaminant concentrations so that plume is shrinking No risc based target concentration could be set because there was no defined risc

8 Humic acids Humic acids function as electron acceptor Reduced humic acid can transfer electrons to ferric iron Biodegradation enhanced by Addition of suitable electron acceptor (humic acid) Enabling the use of mineral-bound ferric iron Organic carbon Reduced humic acid Fe (II) Microorganism CO 2 Oxidised humic acid Fe (III) Mineral particle

9 Humic acids Fine humified material Environmentally safe Health concerns only when handling dry powder (lung irritation when respired) Humus is partially decomposed soil organic matter. Humalite is one type of humus materials found adjacent to sub-bituminous coalfields in Alberta, Canada. Humalite is similar to lignite and leonardite, but is lower in ash and toxic metals. This makes humalite one of the highest quality humus materials in the world.

10 Case First case in Finland (Europe?) where humics were used for ground water remediation Pilot study was performed in defined area at the site before the full scale remediation was designed In later cases, no pilot study is suggested when using humics Pilot studies in restricted area at the site difficult to see the effect Safe product, no risk in deteriorating the ground water quality even if the remediation did not work If this method is estimated to be suitable for the site, it most likely works Designing full scale remediation does not require pilot study After the pilot study, environmental permit was applied and granted for the full scale remediation

11 Case

12 Case Humics injected 3 times during the pilot to the restricted area 4 times during two year full scale remediation During full scale remediation 3-30 kg/well Along with 1,4-2,9 m 3 water (anaerobic water from the site)

13 Case Injection to existing monitoring wells by gravity

14 Case 2004 before pilot study

15 Case 2005 after pilot study

16 Case 2009 after remediation

17 Case Two years monitoring after the active remediation To verify that there will be no rebound In 2010 concentrations remained as low as in the 2009 If the situation remains same, the site closure will be proposed in the end of 2011

18 engineering earth's development preserving earth's integrity

19 TOC (mg/l) Injektointi (kg) 140,00 TOC (mg/l) 70,0 120,00 100,00 60,0 50,0 GA2 GA4 80,00 60,00 40,00 20,00 0,00 40,0 30,0 20,0 10,0 0,0 GA5 GA6 GA7 GA13 GA14 Injektointi yhteensä (kg)

20 DO (%) Injektointi (kg) 70,00 DO (%) 70,0 60,00 50,00 60,0 50,0 GA2 GA4 40,00 30,00 20,00 10,00 0,00 40,0 30,0 20,0 10,0 0,0 GA5 GA6 GA7 GA13 GA14 Injektointi yhteensä (kg)

21 Redox (mv) Injektointi (kg) 300,00 Redox-potentiaali (mv) 70,0 200,00 100,00 0,00-100,00-200,00-300,00 60,0 50,0 40,0 30,0 20,0 10,0 0,0 GA2 GA4 GA5 GA6 GA7 GA13 GA14 Injektointi yhteensä (kg)

22 Fe (mg/l) Injektointi (kg) 9,00 8,00 7,00 6,00 5,00 4,00 3,00 2,00 1,00 0,00 Liukoinen Fe (mg/l) 70,0 60,0 50,0 40,0 30,0 20,0 10,0 0,0 GA2 GA4 GA5 GA6 GA7 GA13 GA14 Injektointi yhteensä (kg)

23 ph Injektointi (kg) 7,50 ph 70,0 7,00 6,50 60,0 50,0 GA2 GA4 6,00 5,50 5,00 4,50 4,00 40,0 30,0 20,0 10,0 0,0 GA5 GA6 GA7 GA13 GA14 Injektointi yhteensä (kg)

24 Alkaliniteetti (mmol/l) Injektointi (kg) 3,50 Alkaliniteetti (mmol/l) 70,0 3,00 2,50 60,0 50,0 GA2 GA4 2,00 1,50 1,00 0,50 0,00 40,0 30,0 20,0 10,0 0,0 GA5 GA6 GA7 GA13 GA14 Injektointi yhteensä (kg)

25 SO4(mg/L) Injektointi (kg) 60,00 SO4 (mg/l) 70,0 50,00 40,00 30,00 20,00 10,00 0,00 60,0 50,0 40,0 30,0 20,0 10,0 0,0 GA2 GA4 GA5 GA6 GA7 GA13 GA14 Injektointi yhteensä (kg)