Bioremediation and Bionanotechnology

Dr Russell Thomas, Parsons Brinckerhoff

19th May 2010

What’s he talking about?

• Purpose - An Industrial perspective on some of the different methods of bioremediation employed in the Contaminated Land Industry.

• Through:• An explanation of contaminated land.• An explanation of the application of

bioremediation. • A few examples of different types of

bioremediation.

What is Contaminated Land? – Simple terms

• People like this.

• Carried out processes like this .

• producing by-products like this.

• Some of the by-products were lost through leakage and accidental spillages.

What is Contaminated Land? – complex terms• The contaminated land regime is enshrined in Part 2A of the Environmental Protection

Act 1990.

• Section 78A(2) of the Act defines Contaminated Land as:   

• “any land which appears to the Local Authority in whose area it is situated to be in such a condition, by reason of substances in, on or under the land, that: 

A. Significant  harm  is  being  causes  or  there  is  significant possibility of  such harm being caused; or  

B. pollution  of  controlled  water  is  being,  or  is  likely  to be caused”.

• A pollutant linkage must exists between a “Contaminant Source and a Receptor by means of a Pathway”. All of these factors must be present for a site to be considered as “Contaminated Land”.

 

Source

(Contaminant, e.g. oil)

Pathway – (migration into river)

Receptor

(Person/controlled waters)

Remediating contaminated Land

• Where land is classified as “contaminated land” then it will need to be remediated.

• Through the planning regime where polluted land is to redeveloped it must be made suitable for use through remediation.

• Remediation is the use of a technique which will break the pollutant linkage, by:• Removal of the pollutant source;• Breaking of the pathway; or • Restricting access by the receptor.

Types of Sustainable Remediation

Remediation techniquesSoil Washing

Disposal to landfill

PermeableReactive barriers

Thermal treatment

Composting

Slurry Phase Bioreactors

Stabilisation

In-situ Bioremediation

Landfarming/ Biopiles

Cover systems

Bioremediation options

Bioremediation

• Bioremediation is defined by the American Academy of Microbiology as

• 'the use of living organisms to reduce or eliminate environmental hazards resulting from accumulations of toxic chemicals or other hazardous wastes‘[i].

[i] Gibson, D.T and Sayler, G.S., Scientific Foundations of Bioremediation: Current Status and Future Needs. Washington, D.C.: AAM & ASM; 24, 1992.

Bioremediation – how?

H H H H H H H

H C C C C C C C H

H H H H H H H

CO2

H2O

• Bioremediation harnesses biological processes by optimising the chemical and physical parameters that affect the rate of bioremediation. These include: • supplying sufficient water and nutrients • increasing the temperature closer to the organism’s

optimum (often 30oC);• and increasing the rate of mixing or aeration.

• The bioremediation of organic compounds is referred to as biodegradation, this is where organisms breakdown the target chemical through metabolic processes. preferentially into harmless by-products.

Napthalene Biodegradation Pathway

Phenol Degradation

Continued Continued biodegradationbiodegradation

Landfarming/Biopiling

• Landfarming and Biopiles are similar methods, soil is excavated, conditioned, so oversize material is removed and formed into piles.

• For Landfarming the soil is formed in long piles called windrows, the soil is turned over regularly.

• For Biopiles, the soil is formed in piles and air (can be heated) is blown into or sucked through pile through perforated pipes.

• In both cases nutrients are supplied along with regular watering and tilling.

• Microorganisms utilise the organic contaminant for growth.

Landfarming

•The process is relatively cheap, suitable for simple hydrocarbons and proven in the UK.

•It is not generally suitable for some soil types (e.g. clay) or some complex organics (5 ring PAH) and the rate of degradation is relatively slow.

Landfarming – Treatment of Coal Tar

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H (

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)2-ring3-ring4-ring5-ring6-ringtotal

Some limited degradation of 5 ring PAH

Rapid degradation of the total PAH

2- ring PAH are not generally present in significant quantities in weathered tar

Composting

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Biodegradation performance

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Biodegradation performance

• Composting is generally a faster process and would be used in the same situations as landfarming, though it is used preferentially where shorter timescales are required.

• Composting is very similar to Landfarming and Biopiles, but requires additional of 10-15% manure, is carried out at circa 70°C, and the microbiology is predominantly Fungal.

Slurry Phase Bioremediation

Soil mixed in reactor vessel at 20-40% wt/volume slurry loading. Treatment occurs between 3-10 days. Temperature maintained at 25-30oC and pH Neutral. Dissolved oxygen monitored to indicate microbial activity. Degradation should occurs at optimum rate.

Laboratory Scale

Full Scale

Slurry Phase Biodegradation

Slurry particle coated in organic contaminant

Diffusion of contaminants (PAH) into the aqueous phase and absorption by bacteria, Contaminants then degraded.

Bacteria (planktonic) within the water phase will also degrade dissolved contaminants.

Soil is mixed and aerated intensively in a water phase, suspending soil particles.

Bacteria form biofilm on slurry particle.

Bioslurry Reactor – Example Performance Data

overall

21116

ContaminantTotal Polycyclic

Aromatic Hydrocarbons Benzo(a)PyreneTotal Petroleum Hydrocarbons,

Fraction Solids fines overall Solids fines overall solids fines

Starting material 422 5910 1412 43 606 145 6314 88393

Treated Material 245 882 361 19 115 36 6313 13375 7590

% biodegraded 42 85 75 56 81 75 0 85 64

Bioslurry reactors are, energy intensive, technically complex and fraught with engineering problems.

Best suited for the treatment of fines from soil washing or fine grained sands or clays which are contaminated with compounds which are not easily biodegraded.