BBE 4302 Midterm 4 :P

Environmental Remediation

Detoxification or removal of contaminants or pollutants from an environmental medium (soil, ground water, etc.)

Methods of environmental remediation

1. Pump and treat

2. In situ detoxification

3. Vapor extraction

4. Excavation

PIVE

Top three most commonlyused remediation approaches according to Atlas and Philip (2005)

1. Incineration

   1. most expensive (need high temperatures)

2. Thermal desorption

3. Solidification/stabilization

SIT

What is the process for PFAS remediation via Sequestration and Immobilization?

List its function, advantages, and limitations.

Process: Soil is amended with a sorbent e.g. activated carbon or biochar

Function: Sorbent binds PFAS and immobilizes it in the environment, reducing PFAS escape to groundwater or leachate

Advantages:

• readily available commercial sorbents

• in-situ or ex-situ treatment

• cost-effective

Limitations:

• long-term stability of binding is questionable

• does not destroy PFAS

• amount of sorbent required could have implications for land use management

What are organic compounds?

Molecules with carbon AND hydrogen

What is the separation process of soil washing?

List its function, advantages, and limitations.

Process: Solid is washed with or without addition of a solvent

Function: transfer contaminants from soil to wash solution. Wash solution is then collected and treated

Advantages:

• lower infrastructure requirements than destructive technologies

• can recover treated soils

Limitations:

• not applicable to all soil types (e.g. clay, heavy soils)

• requires excavation of soils

• in-situ treatments problematic

• produces contaminated liquid (needs extensive treatment)

What is the separation process of soil liquefractionation?

List its function, advantages, and limitations.

Process: soild mixed with liquid, forms a slurry, which is fractionated, producing a foam

Function: PFAS readily transitions to air-water interface (foam) which can then be removed

Advantages:

• potentially an in-situ treatment

• high removal efficiency

Limitations:

• not applicable to all soil types (e.g. clay)

• high cost

• requires secondary treatment of foam fraction

What is the destructive process of chemical oxidation?

List its function, advantages, and limitations.

Process: pump chemical oxidant into solid, followed by optional downstream extraction

Function: oxidizes PFAS to CO2 or more readily degradable substances

Advantages:

• converts PFAS to more biodegradable substrates or directly destroys PFAS

Limitations:

• requires large volumes of oxidants

• requires additional safety measures (if drinking water)

• inefficient

• solid must be highly permeable

• carbonate and organic substances interfere

What is the destructive process of thermal?

List its function, advantages, and limitations.

Process: soil excavated and treated with high temperatures (500C)

Function: PFAS pyrolyzed

Advantages:

• high degradation rates >90%

• Treats variety of PFAS

• Potential for biochar of syngas

Limitations:

• high disruption to environment

• destroys soil

• expensive

• production and emission of HF, partially fluorinated compounds, and volatilized PFAS ☹

What are the different methods for treating PFAS contaminated soils?

1. Sequestration and Immobilization

2. Separation

   1. soil washing

   2. soil liquefractionation

3. destruction

   1. chemical oxidation

   2. thermal

List potential advantages and challenges of bioremediation

Advantages:

• in-situ applications

• cost effective

• easy application

• reduced environmental disruption

Challenges:

• slow rates

• contradictory degradation results

• non-resolved degradation mechanisms

Bioremediation

use of microorganisms, plants, or their metabolites to detoxify or remove pollutants

Phytoremediation

bioremediation with plants

Phytoextraction

uptake of contaminants into roots or transport into stem/leaves

Rhizodegration

bioremediation of contaminants occurring in rhizosphere (mostly due to microbes)

Phytodegration

Biodegration of compounds by the plants themselves

Phytovolatilization

release of contaminants through transpiration of water by plants

Why are microbes suited for environmental remediation?

1. Heartless and gutless

2. riddled with mutants

3. go to extremes

4. prolific

5. may already be working for you

Mycoremediation

Fungal biodegradation = bioremediation with fungi

Xenobiotic

Synthetic, not found in nature

What do we want to remediate?

1. organics

2. organometallics

3. metals

some natural, some xenobiotics

Organic Compounds

compounds that contain the element carbon (C), generally

Types of hydrocarbons

1. alkanes

2. alkenes

3. alkynes

4. arenes

PAH (polyaromatic hydrocarbons)

ubiquitous in fossil fuels

formed from incomplete combustion of any carbon-based fuel

Lipophilic (oil-soluble) solid, but sometimes a particulate in air

Mutagen

causes mutations (most are also carcinogens)

Carcinogen

causes cancer

Teratogen

causes birth defects

Other examples of organic compounds include:

haloaromatics (ex. Penta)

nitroaromatics (ex. TNT)

organophosphates (ex. Parathion)

DDT (Dichlorodiphenyltrichloroethane

Paul Muller won the nobel prize for its synthesis in 1948

used as a pesticide against arthropods

banned in 1972 after ‘silent spring’

Organometallic compounds

organic compound with associated metal element

ex. methyl mercury

• teratogenic

• potential chronic effects (heart attacks, etc.)

• bioaccumulative

Inorganic compounds

contain no carbon

Typically in bioremediation, “inorganic” == “metals”

Ex. CCA (chromated copper arsenate)

• fixing agent, fungicide, insecticide

• BANNED

Methods for applying the biodegradation process fo rremediation?

1. Passive in-situ (natural attenuation)

2. Promoted in-situ

3. Inoculation

4. Ex-situ treatment (solid and slurry)

5. Engineered systems treatment

Passive in-situ (natural attenuation)

using native microbes/plants and chemicals

Promoted in-situ

biostimulation: adding oxygen or nutrients to stimulate native organismal activities

O2 is key

To acquire energy, organisms often shuttle______ to store energy chemically to a ________ _________ _________.

To acquire energy, organisms often shuttle electrons to store energy chemically to a terminal electron acceptor.

Which electron acceptors are for aerobic processes and which are for anaerobic processes?

O2

NO3(-3)

Mn(+4)

Fe(+3)

SO4(-2)

O2 — aerobic

NO3(-3) — anaerobic

Mn(+4) — anaerobic

Fe(+3) — anaerobic

SO4(-2) — anaerobic

Inoculation

Bioaugmentation

adding microbial suspension or enzymes

ex. planting vegetation

What are four key advantages to bioremediation with fungi?

1. filamentous fungi have a high surface area: volume ratio

2. ‘slimy’ hydrophobic extracellular sheath

   1. part of biofilms AND have a medium that improves compound capture

3. tolerate environmental stress adn fluctuations

   1. i.e. desiccation and fluctuations in temperature

4. can biodegrade many pollutants

hydrophobin

cysteine-rich proteins that are small (100 amino acids, <20kD)

havea. hydrophobic and hydrophilic dual orientation

What enzymes are involved in fungal enzymatically-mediated oxidation of lignin?

lignin peroxidase

manganese peroxidase

versatile peroxidase

laccase

Lignin peroxidase

most prevalent = breaks lignin bonds

manganese peroxidase

breaks lignin molecule

versatile peroxidase

breaks lignin bonds, but Mn-dependent

Laccase

breaks lignin molecule??? Function unclear!

Co-metabolism

enzymes secreted to metabolize compound #1 also metabolize compound #2

Mn peroxidase secreted to degrade lignin will co-metabolize PAHs, Dioxins, etc.

Add _____ to lure _____ _____ fungi and to ‘trick’ them into expressing/secreting __________

Add mulch to lure white rot fungi and to ‘trick’ them into expressing/secreting Mn peroxidase

Mycofiltration

using mycelial mats formed by fungi as a living filter

will likely not be pure

Are lumber products in high demand?

Yes

List reasons to use lignocellulose:

• less carbon emissions

• more sustainable; renewable

• abundant

CO2 emissions from fossil fuels usage is now approximately ______________ of carbon per year; The atmosphereic CO2 concentration is _________ parts per million (ppm) and likely double by 2050

CO2 emissions from fossil fuels usage is now approximately 7 Gt of carbon per year; The atmosphereic CO2 concentration is 400 parts per million (ppm) and likely double by 2050

Renewable

Synthesized by consuming solar energy and can provide sustainable carbon sources

Goals for feedstocks

• fast growth

• quality raw material

• low maintenance requirements

• environmentally friendly

• high ‘digestibility’

Example of a fast growing lignocellulosic feedstock

Pinus radiata

world’s most planted conifer

used for lumber and papermaking

reserachers looking at biorefining

Example of a quality raw material of lignocellulosic feedstock

Eucalyptus

long, uniform fibers for papermaking

Example of a low maintenance lignocellulosic feedstock

switchgrass

• requires little fertilizer

• drought-tolerant

• pest-resistant

• excellent on ‘degraded’ soils

Example of a environmentally friendly lignocellulosic feedstock

mixed native prairie-grasses

• deep roots store carbon underground

  • can renew degraded land

• no herbicides

• maintain native ecosystem

• conserve biodiversity

• more biomass than monoculture

• more ‘stability’ in the polyculture system

Example of a highly digestible lignocellulosic feedstock

hybrid poplar

What good available biomass feedstocks are there in minnesota?

corn stover, switchgrass, wheat straw, poplar/aspen, and MSW

Biorefinery

a facility that integrates biomass conversion processes adn equipment to produce fuels, power, and chemicals from biomass

involves fractionation

fractionation

separating (refining) the individual components of lignocellulose for utilization

What can you make from cellulose?

• fiber for paper

  • longer fibers == better paper

• fiber for textiles (fabric)

  • rayon, modal, etc.

• Nanofibers

  • fiber for strengthening materials

• alcohols

What can you make from hemicellulose?

• alcohols

• solvent for fibers during pulping (papermaking)

• industrially-important chemicals (ex. furfural)

What can you make from lignin?

• burn for energy

• thermoplastics, foams, other materials

• lignin valorization for producing value-added products

What can you make from extractives?

• industrial chemicals (tannins, terpeniods, resin)

• sap for latex

What can you make from bark?

• cork

• mulch (fertilizer)

• charcoal or energy

Bioprocessing

production of a commercially useful chemical or fuel by biological process, such as microbial fermentation or degradation

ex. biobleaching: deligninification via white rot fungi for papermaking

Goals for biodegradative organisms/systems:

1. fast acting

2. highly selective and efficient

3. robust

4. low cost

5. compatible with other degradative systems

6. multifunctional

Example of a fast acting biodegradative organism/system?

Clostridium degrading lignocellulose

colony growth REALLY fast

high activity level enzymes

rapid metabolism organisms

Example of a high selective and efficient biodegradative organism/system?

Phanerochaete chrysosporium

seletive delignification

not fast acting

no unwanted side reactions

no loss of desired product

Example of a robust biodegradative organism/system?

thermophilic bacteria/fungi

maybe fast acting or selective

endure temperature/pH ranges

long lived

non-specific nutrient requirements

Example of a compatible with other degradative systems biodegradative organism/system?

Cellulosic ethanol

Cooperative bioprocessing

bioprocessing with multiple organisms

natural degradation often involves synergy between organisms

ex. bacterial colonization of wood may provide nitrogen for wood-degrading fungi

Consolidated bioprocessing (CBP)

using one ‘multi-tasking’ organism

ex. a bacteria that produces cellulase AND can fermet ethanol

Bioprospecting

surveying biological organisms in general for potential utilization

Three ways to ‘harness’ an organism of interest for bioprocessing

1. direct utilization

2. bioengineering

3. biomimicry

amylase

catalyzes the starch degradation to produce glucose

One bushel of corn grain (56lbs) ==

3 gallons ethanol + 17lbs DDGS + 17lbs CO2

Steps to produce cellulosic ethanol?

Pretreat

conditioning

saccharification

co-ferment

Pros of cellulosic ethanol over corn ethanol:

• variable feedstock

• abundant

• reduce 86-90% GHG emissions

• 5x better net energy balance

Cons of cellulosic ethanol compared to corn ethanol:

• more expensive

• more enzymes needed

• enzymes more expensive