1. Presented by : A.R.M Sharif Nawyaz
Monisha Alam
Sharmeen Moushumi

2. Outline
• Definition
• Methods
• Process Descriptions
• Advantages & Disadvantages
• Applicability
• Limitation
• Cost & Performance
• Case Study
• Conclusion & Recommendations

3. What is In-Situ Bioremediation?
In place, on site Remediation by Microorganisms
In-situ Bioremediation

4. Process of In-Situ Bioremediation
Contaminant
intake
Digestion &
Metabolism
Non-toxic end
products released
Non Toxic End Products- CO2 & H2O (Aerobic)
CH4 , SO4
2- etc. (Anaerobic)

5. In-Situ
Bioremediation
Intrinsic/Natural Attenuation
(no site manipulation)
Enhanced/
Engineered Bioremediation
(site & microbial manipulation)
Biostimulation Bioaugmentation
Bioventing Air Sparging
Phyto-
remediation
Land
Farming
Methods of In-Situ Bioremediation

6. Alteration or manipulation of environmental conditions to
enhance microbial growth & activity
Lack of proper condition to
survive & growth
Bio-stimulation
Addition of adequate nutrients
(N, P, S, Ca, Mg etc)
Biostimulation

7. Soil unsaturated zone mostly aerobic O2 required
•Modification of
Soil Vapor
Extraction (SVE)
•Low air flow rate
• O2 in soil air
above 2%
Bioventing process
Bioventing

8. Landfarming
• Tilling soil, adding fertilizer, surfactants etc.

9. Bioaugmentation

10. Advantages Disadvantages
•Easy & Low cost
•Combines with
other technologies
•Less Fugitive emission
•Public acceptance
•Requires long time
•Contaminant
mobility increases,
leaching ground
water
•Less certainty of
uniform treatment
•Complete destruction,
no residuals
Advantages & Disadvantages

11. Site Conditions
Factors affecting
Contaminant
properties
Required Data: Soil properties and contaminants’
physical & chemical properties
Applicability

12. • Microorganisms present in soil able to degrade the
contaminants
• Adequacy of Nutrients – sufficient N, P, S, Ca, Mg etc.
• pH- 6 to 8
• Temperature – optimum 20° C to 30°C
• Moisture Content – 40-60% of the field capacity
• Bioavailability of contaminants to microorganism
• Oxygen availability – for aerobic microorganisms
• Soil Permeability & Homogenity
• Organic fraction of soil
Favourable Site Conditions

13. Following properties of contaminants affect applicability:
• Biodegradability
• Source
• Distribution in soil
• Solubility & sorption coefficient
• Chemical reactivity
• Volatility
Contaminant Properties

14. •Polyaromatic Hydrocarbons (PAH)
• Semi Volatile Organic Compounds (SVOCs, TCE & PCE)
• BTEX (Benzene, Toluene, Ethylene, Xylenes)
• Petroleum Hydrocarbons (PHC) (Gasoline, diesel, fuel)
• Pesticides
• Organic Solvents
• Wood Preservatives
Treated Contaminants

15. PAH Biodegradation

16. Limited to following site conditions:
•Low temperature – slows down biodegradation
• Clay, highly layered, or heterogeneous soil- limiting
transfer of oxygen or other electron acceptor
Limited for contaminants:
•Highly chlorinated organics like PCB
•heavy metals
•inorganic salt
Biodegradation resistant, because-
•Toxic for microorganism
•Microbes prefer feeding on other substrate
•Lack of microbes’ genetic capability to use them as source
of Carbon & energy
Limitations

17. Operational Limitations:
•Capacity of bioventing wells decreases with time
•Profuse microbial growth-clog the injection wells
•Circulation of water-based solutions through soil
increases contaminant mobility and necessitate
treatment of underlying ground water
Limitations (cont’d..)

18. • Effective if cleanup achieved in a compatible time
frame
• Simultaneous treatment of soil & ground water
• High efficiency of bioventing combined with SVE.
• Remediation time: 1 to several years
• Higher MW compounds take longer to degrade
Performance

19. • Less expensive over ex-situ methods
 Cost depends on: Site condition & Contaminants
• Larger site: lower unit cost
 In-situ bioremediation cost/m3
 Enhanced bioremediation: $30 to $100
 Bioventing: $ 79 to $928
 Phyto-remediation: $147 to $2322
 Other process cost/m3
In-Situ - SVE: $405-$1275,
Solidification/Stabilization: $150-$250
Ex-Situ - Biopiles: $130-$260
Composting: $370-$442
Cost

20. Site name &
Location
Contaminants Cost Duration
Reduction in
Contaminant
Concentration
Toronto,
Canada
BTEX, TPH
Approx.
$42/m3
Approx. 4
months (1995)
7,000 ppm to
<100 ppm
Longwood TS,
ON, Canada
BTEX, TPH
Approx. Total
$65,000
Approx. 30
days (1995)
14,000 ppm to
<100 ppm
Ontario,
Canada
PAH, PCP
Approx. Total
$741,000
1993-1994
439 mg/Kg to
10-50 mg/kg
Cost & Performance - Overview

21. CCME report 2001 estimated that 60% of
Canada’s contaminated sites involve PHC
contamination
Challenges faced
•Low temperature
•Characterization of contaminants
•Inappropriate analytical methods
•Complexity of site conditions
Application in Alberta

22. Site Strachan Gas plant – Near Rocky mountain House
Period Late summer to mid winter, 1994
Technology Bioventing preceded by SVE.
Contaminants NG gas condensate, BTEX, PAH, amine, BTEX Conc. 10-20
mg/L in HC plume.
Contaminant area- 1 hectre
Waste source LPG recovery area of the plant
Result Total removal 17,000 kg, 3,500 kg degraded through
Bioventing
Cost Capital cost: $150,000, Semiannual operating cost: $ 15,000
, unit cost about $10/kg
Details From Dec 1994 to march 1995 biodegradation rate: 200
kg/day, Air flow rate: 50 L/s
Case Study

23. Present condition of the site
Source : http://sulvaris.com/company/projects/

24. Conclusion & Recommendation
• Effective application in Canada & Alberta
• Bioventing preceded by SVE - better performance
• Inadequate site characterization-leads to under design or
overdesign; influence time!
• Low cost, lower risk to site workers & public
• Complete contaminant destruction
• Ecologically acceptable