Bio Remediation

BIOREMEDIATI ON

Conventional methods of remediation

Dig up and remove it to a landfill

sk of excavation, handling and transport of hazardous material ry expensive to find another land to finally dispose these materials

Cap and contain

Maintain it in the same land but isolate i

• Only an interim solution • Requires monitoring and maintenance of isolation barriers for a long time

Products are not converted into harmless products. Stay as a thre

Is there a better approach?

Better approaches

estroy them completely, if possible

Transform them in to harmless substance Methods already in use High temperature incineration Chemical decomposition like dechlorination, UV oxidation

But, are they effective?

Yes But only to some extent Drawbacks  Technological complexity  The cost for small scale application – expensive  Lack of public acceptance – especially in incineration

• Incineration generates more toxic compounds • Materials released from imperfect incineration – cause undesirable imbalance in the atmosphere. Ex. Ozone depletion • Fall back on earth and pollute some other environment • Dioxin production due to burning of plastics – leads to cancer

 May increase the exposure to contaminants, for both workers and nearby residents

Bioremediation makes effective better approach possible.

by destroying or render them harmless using natural biological

Relatively low cost Low technology techniques Generally has general public acceptance Can often be carried out on site – no excavation, no transpor

wbacks

y not be effective on all contaminants ay me duration – relatively long pertise required to design and implemen hough not technically complex though

• is a general term referring to the microbially mediated decomposition of paper, paint, textiles, concrete, hydrocarbons • Superior technique over using chemicals – why? 3.Microorganisms – easy to handle 4.Easy to clear – using antibiotics

Types of Biodegradation 1. Minor change in a molecule 2. Fragmentation 3. Complete mineralization One example to describe all 3 types

Minor change in a molecule (dehalogenation) Cl Cl

O

CH2

COOH

HOH

OH HO

O

CH2

COOH

Cl

Cl is replaced with OH

Fragmentation Cl Cl

O

CH2

COOH

HOH

OH

HOCH2-COOH

HO

OH

ginal structure can still be recognized in these two types. Bu

Mineralization Cl Cl

O

CH2

HOH

COOH

2Cl

CO2

Completely converted into inorganic forms

• is defined as the process whereby organic wastes are biologically degraded under controlled conditions to an innocuous state, or to levels below concentration limits established by regulatory authorities

2 types

Engineered Bioremediation  Intentional changes

Intrinsic Bioremediation

 Simply allow biodegradation to occur under natural conditions

Factors affecting Engineered Bioremediation Qualities of microorganism & environment Sources of microorganisms Disadvantages of GEMs

1. Contact between the microbes and the substrate 2. Proper physical environment 3. Nutrients 4. Oxygen 5. Absence of toxic compounds

• Able to degrade hydrocarbons • Able to fix nitrogen • No secondary/side effects

• Presence of accessory nutrients (N P K F • Absence of heavy meta • Adequate O2, Temperature, p



From contaminated field sites (with varying environmental conditions subzero temperatures or extreme heat, desert conditions or in water, with excess of oxygen or in anaerobic conditions, with presence of hazardous compounds or on any waste stream)

 From culture collections  Genetically Engineered Microorganisms (GEMs)

Mainly 3 reasons… • Lab strains become food source for soil protozoa • Inability of GEMs to contact the compounds to be degraded • Failure of GEMs to survive/compete indigenous microorganisms. Mostly due to lack / decreased activity of House Keeping Genes.

- a bioremediation under natural condition

• is a natural attenuation process that leads to the decrease in contaminant levels in a particular environment due to unmanaged physical, chemical and biological processes. Is it advantageous over engineered bioremed.? May give unexpected results

• Microbes in Hudson river mud developed an ability to partially degrade PCB (Poly Chlorinated Biphenyls) Process occurs in 2 steps Partial dehalogenation of PCBs occurs naturally under anaerobic conditions Less chlorinated residues

Then mud is aerated to promote the complete degradation of these less chlorinated residues

Bioremediation in ALASKA OIL SPILL

South Central Alaska • South Central Alaska is beautiful and unique. • Prince William Sound, surrounded by land from the Chugach National Forest • Has many islands, bays, and fjords, giving it more than 2,000 miles of shoreline and making it one of the nation’s largest relatively undeveloped marine ecosystems

video

Decisions had to be made! • The oil was spreading and contaminating more and more beaches every day. • Clean-up methods had to be decided upon to prevent further spreading of the oil.

• Panel of experts in this field was assembled on April 17-18, 1989, to discuss the feasibility of using bioremediation in Alaska • Recommended EPA to apply fertilizer (the addition of nutrients) on small scale plots

• Could the technology be applied to an environment so cold? • Were there favorable conditions for degradation of petroleum hydrocarbons? • Is Prudehoe Bay Oil of sufficient quality for biodegradation?

• Scientists knew that this type of oil was degradable from past studies • Now they needed to know the concentrations of native hydrocarbons degraders.

Is there anything called native hydrocarbon degrader? If so, How?

• Naturally Hydrocarbons have been added to the environment by pine tree droppings and natural seeps for millions of years • Carbon-hydrogen bonds of hydrocarbons yield very high energy • This became an excellent energy source that allowed a complex community to evolve over millions of years to degrade these hydrocarbons • Also, isolated in Prince William Sound that degrade petroleum and it’s

• So, they expected accumulation of these organisms in the oil spilled areas • Found 10,000-fold increase of oileating microbes in contaminated What were the organisms found? areas

Acinetobacter Calcoaceticus Alcaligenes sp. Arthrobacter/Brevibacterium sp. Flavobacter/Cytophaga Oceanospirillum sp. sp. Pseudomonas putida Pseudomonas Pseudomonas sp. fluorescens Trichosporon sp. Pseudomonas stutzeri Pseudomonas his large community of microorganisms made i vesicularis unnecessary to introduce Vibromicrobes. sp.

Then type of Bioremediation

• Scientists knew that biodegradation was occurring. But to speed up the process… • Wanted to know the limiting factors • Nitrogen and Phosphorous in seawater are severely limiting to microbial hydrocarbon degradation (had already been published) • Is Oxygen a limiting factor? – No • Is Temperature a limiting factor? Yes

• Started on May of 1989 on Knight Island • This project was designed to determine the feasibility of biodegradation enhancement by adding fertilizers • Nutrient applications began on June 8, 1989Selected at Snug Harbor, on it had a as the first testlocated site because long length of shoreline several beach mate the southeastern side with of the island

• Approximately after 10 to 14 days visual reductions in the amount of oil covering the rocks were apparent • also a visual reduction in the oilcovered sand and gravel beach • Further tests proved that this reduction is due to BIOREMEDIATION and to prove that this is not due to chemical cleaning.

Based on the promising results of the initial field test at Snug Harbor and the absence of any adverse effects on the area’s ecosystem, EPA recommended in July that the bioremediation efforts be scaled up during summer. By the end of the summer of 1989, 74 miles of shoreline were treated with nutrient applications

n situ Bioremediation (at the site)

Ex situ Bioremediation (away from the site)

• Bioventing involves supplying air and nutrients through wells to contaminated soil to stimulate the indigenous bacteria.

• Biosparging involves the injection of air under pressure below the water table to increase groundwater oxygen concentrations and enhance the rate of biological degradation of contaminants by naturally occurring bacteria.

• Bioaugmentation involves practice of adding specialized microbes or their enzyme preparation to polluted matrices to accumulate transformation or stabilization of specific pollutants

• Landfarming involves a simple technique in which contaminated soil is excavated and spread over a prepared bed and periodically tilled until pollutants are degraded.

• Composting Traditional method to convert waste into household usable materials involves combining contaminated soil with nonhazardous organic amendants such as manure or agricultural wastes. The presence of these organic materials supports the development of a rich microbial population and elevated temperature characteristic of composting.

Where did they get the concept from? • Evolutionary some plants have evolved the capacity to take up and accumulate selected metals in their shoots in levels that are toxic to ordinary plants • Some plants have developed symbiotic association with microbes that can degrade certain pollutants

Introduction Although the application of microbe biotechnology has been successful with petroleum-based constituents, microbial digestion has met limited success for widespread residual organic and metals pollutants. Vegetation- based remediation shows potential for accumulating, immobilizing, and transforming a low level of persistent contaminants. In natural ecosystems, plants act as filters and metabolize substances generated by nature.

Term coined in 1991

5 types based on the fate of contaminants 5

1 2

3

4

Rhizofiltration Phytoextraction Phytotransformation

Phytodegradation

Phytostabilization

• Also called Phytoaccumulation • A process used by the plants to accumulate contaminants into the roots and shoots or leaves. • Technique saves tremendous remediation cost by accumulating low levels of contaminants from a widespread area (usually metals)

• Also called Phytodegradation • refers to the uptake of organic contaminants from soil, sediments, or water and, subsequently, their transformation to more stable, less toxic, or less mobile form. • Metal chromium can be reduced from hexavalent to trivalent chromium, which is a less mobile and noncarcinogenic form.

• Leachable (permeate gradually) constituents are adsorbed and bound into the plant structure so that they form a stable mass of plant from which the contaminants will not reenter the environment

• Also called rhizodegradation • is the breakdown of contaminants through the activity existing in the rhizosphere. • Due to the presence of proteins and enzymes produced by the plants or by soil organisms such as bacteria, yeast, and fungi. • a symbiotic relationship that has evolved between plants and microbes • Plants provide nutrients necessary for the microbes to thrive, while microbes provide

• is a water remediation technique that involves the uptake of contaminants by plant roots • used to reduce contamination in natural wetlands and estuary areas

The wide part of a river where it nears the sea; fresh and salt water mix

• use at very large field sites where other methods of remediation are not cost effective or practicable • use at sites with a low concentration of contaminants where only polish treatment is required over long periods of time • in conjunction with other technologies where vegetation is used as a final cap and closure of the