Bioremediation Techniques Quiz
40 Questions
0 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the primary purpose of biopiles in bioremediation?

  • To completely eliminate all contaminants in soil.
  • To facilitate the assimilation of heavy metals into plant roots.
  • To enhance the leaching and volatilization of contaminants. (correct)
  • To provide a controlled environment for microbial activity.

    • Which type of reactor is specifically designed for the three-phase mixing of solid, liquid, and gas to enhance bioremediation rates?

  • A cellular reactor.
  • A continuous flow reactor.
  • A slurry bioreactor. (correct)
  • A batch reactor.

    • What is the result of ortho cleavage of catechol?

  • pyruvic acid
  • acetaldehyde
  • cis,cis-muconic acid (correct)
  • 2-hydroxybenzoic acid

    • Which of the following best describes the process of phytoextraction?

    <p>Plants extract heavy metals and concentrate them in their leaves and stems.</p> Signup and view all the answers

    Which of the following types of phytoremediation is NOT commonly recognized?

    <p>Phytoaugmentation.</p> Signup and view all the answers

    Which pathway does meta cleavage follow when catechol is degraded?

    <p>It forms 2-hydroxymuconic semialdehyde.</p> Signup and view all the answers

    What is the role of the Krebs cycle in the degradation of aromatic compounds?

    <p>It oxidizes degradation products to CO₂ and H₂O.</p> Signup and view all the answers

    What type of microorganisms are typically utilized in a slurry reactor?

    <p>Indigenous microorganisms capable of degrading pollutants.</p> Signup and view all the answers

    What happens to plants after they undergo the process of phytoremediation?

    <p>They are typically harvested and either composted or disposed of.</p> Signup and view all the answers

    What effect does a single substituent on benzene have on its degradation order?

    <p>The order of degradation is significantly affected by the nature of the substituent.</p> Signup and view all the answers

    Which combination of factors increases the persistence of a compound during its biodegradation?

    <p>Increasing the number of chlorine or bromine atoms.</p> Signup and view all the answers

    Why is phytoremediation considered a cost-effective solution compared to other remediation methods?

    <p>It uses natural processes and organisms, reducing operational costs.</p> Signup and view all the answers

    Which of the following compounds are considered recalcitrant?

    <p>Polychlorinated organic compounds</p> Signup and view all the answers

    Which statement is true regarding the biodegradability of xenobiotics?

    <p>Some xenobiotics can be rapidly degraded by microorganisms.</p> Signup and view all the answers

    What is the primary concern regarding mobile recalcitrant compounds?

    <p>They increase toxicity risks for sensitive species.</p> Signup and view all the answers

    Which category of recalcitrant compounds is metabolized extremely slowly but can degrade rapidly in a dense culture of microorganisms?

    <p>Compounds metabolized very slowly</p> Signup and view all the answers

    Which of the following is NOT a condition for an organic substrate to be biodegradable?

    <p>Sufficient temperature range</p> Signup and view all the answers

    What characterizes recalcitrant natural substances?

    <p>They are resistant to different metabolic processes.</p> Signup and view all the answers

    Why is there a lack of understanding regarding the effects of recalcitrant compounds?

    <p>Long-term studies on their environmental impact are limited.</p> Signup and view all the answers

    Which of the following describes a xenobiotic that is not recalcitrant?

    <p>It can be fully degraded in the environment.</p> Signup and view all the answers

    What is a common consequence of bioaccumulation in trophic chains related to recalcitrant compounds?

    <p>Reduction in species diversity.</p> Signup and view all the answers

    What must occur before a molecule can be degraded by microorganisms?

    <p>The molecule must be in an available state.</p> Signup and view all the answers

    Which factor is NOT relevant to the penetration of a substrate inside a cell for degradation?

    <p>Presence of polar solvents</p> Signup and view all the answers

    What condition is essential for the induction of an inducible enzyme?

    <p>Sufficient presence of a specific substrate</p> Signup and view all the answers

    Which of the following contributes to the recalcitrance of a compound?

    <p>Molecule characteristics</p> Signup and view all the answers

    What accurately describes the half-life of a pollutant?

    <p>Time to degrade 50% of the pollutant.</p> Signup and view all the answers

    What are the main components that studies of recalcitrance must consider?

    <p>Chemical, microbiological, and environmental factors</p> Signup and view all the answers

    Which condition is NOT significant for microbial growth in relation to pollutant degradation?

    <p>Presence of hazardous wastes</p> Signup and view all the answers

    Which compound is NOT typically a product of microbial degradation?

    <p>Heavy metals</p> Signup and view all the answers

    Which factor does NOT influence the time required for pollutant degradation?

    <p>Nutritional habits of the microorganisms</p> Signup and view all the answers

    Which phase of hydrocarbon distribution in soils and aquifers is characterized by hydrocarbons that are liquid but not water-soluble?

    <p>Dense Non-Aqueous Liquid Phase (DNAPL)</p> Signup and view all the answers

    What leads to inhibition of degradation by microorganisms?

    <p>Presence of specific inhibitory compounds</p> Signup and view all the answers

    What is the relationship between nutrient concentrations and hydrocarbon biodegradation in natural environments?

    <p>Nutrients typically present in low concentrations can limit biodegradation effectiveness.</p> Signup and view all the answers

    At what pH is the highest degradation rate of hydrocarbons typically observed?

    <p>pH 8</p> Signup and view all the answers

    Which condition is likely to slow down the degradation of hydrocarbons in saturated environments?

    <p>Oxygen diffusion at 100% water saturation</p> Signup and view all the answers

    Which type of microorganism is classified as heterotrophic and utilizes hydrocarbons as a carbon and energy source?

    <p>Heterotrophic Bacteria</p> Signup and view all the answers

    How does the oxygen availability in aquifers affect microbial biodegradation?

    <p>Microorganisms rely on alternative electron acceptors due to low oxygen levels.</p> Signup and view all the answers

    What is the effect of water saturation on microbial access to hydrocarbons?

    <p>Reduced saturation at 100% limits microbial access due to slow oxygen diffusion.</p> Signup and view all the answers

    Which phase of hydrocarbon distribution in soils occurs when hydrocarbons attach to soil or sediment particles?

    <p>Adsorbed Phase</p> Signup and view all the answers

    What is the result of adding nutrients to hydrocarbon degradation processes in natural environments?

    <p>Enhancement of degradation can occur with adequate nutrient ratios.</p> Signup and view all the answers

    Study Notes

    Environmental Biotechnology

    • Bioremediation is a technology using living organisms to detoxify pollutants in soil and water.
    • Bioremediation is preferably done in situ (in the contaminated environment), but can also be ex-situ.
    • Bioremediation can involve processes such as biodegradation, biotransformation and mineralization.
    • Traditional remediation techniques often are not cost-effective and require thorough understanding of microorganisms, their reaction to the environment, and proper implementation.

    Terminology

    • Depollution: the complete or partial elimination of a pollutant using physical, chemical or biological agents
    • Biodegradation: the partial or complete breakdown of a substance by biological agents
    • Biotransformation: transformation of a substance by biological agents (incomplete metabolism)
    • Biostimulation: stimulation of native microflora by adding nutrients and controlling physico-chemical factors (pH, temperature, humidity, oxygen)
    • Bioaugmentation: controlled addition of specific microorganisms to assist native microorganism
    • Bioreduction: reduction of oxidized compounds (e.g., nitrates, metal oxides) through biological means
    • Biolixiviation: extraction of metals from sludge, soil, sediment, mineral by solubilization induced by microorganisms
    • Biofixation/biosorption: The fixation of pollutants (most commonly metals) found in a liquid effluent to microorganisms
    • Xenobiotics: synthetic compounds created by humans, not naturally occurring
    • Phytoremediation: The use of plants to decontaminate soil and water, extracting heavy metals or other contaminants
    • Phytotransformation: Uptake of contaminants in soil/water and transformation by plants
    • Phytostabilization: Preventing contaminant mobility via plant roots/structures
    • Phytoextraction: Plants accumulating contaminants in their parts, harvestable material

    Bioremediation Techniques

    • Ex situ: Bioventing, land farming, biosparging, compositing, biopiles, bioaugmentation, bioreactors, phytoremediation
    • In situ: Bioventing, land farming, biosparging, compost

    Bioventing

    • A common in situ treatment where air/nutrients are supplied via wells, stimulating the native bacteria to biodegrade
    • Low air flow rates are employed
    • Minimizes contaminants released into atmosphere

    Biosparging

    • Air is injected under pressure beneath the water table
    • Enhances groundwater oxygen concentrations, encouraging biological degradation
    • Promotes mixing in the saturated zone

    Biostimulation

    • Involves supplying oxygen and nutrients to stimulate naturally occurring bacteria
    • Effective treatment for soil and groundwater environments

    Bioaugmentation

    • Utilizes the addition of microorganisms (indigenous or exogenous) to contaminated sites to enhance bioremediation
    • Limitations: non-indigenous cultures may not compete well or create stable populations, most soils have indigenous microbes capable of effectively degrading waste.

    Land Farming

    • Contaminated soil is excavated, spread and tilled until the pollutants are degraded
    • Aims to stimulate indigenous microorganisms to aerobically degrade contaminants

    Composting

    • Combines contaminated soil with non-hazardous organic amendments (like manure) to cultivate a rich microbial population, characterized by elevated temperatures.

    Biopiles

    • Hybrid of landfarming and composting
    • Engineered cells for aerated and composted piles
    • Effective treatment for soils contaminated by hydrocarbons (refined version of landfarming)

    Bioreactors (Slurry Reactors)

    • Ex-situ method
    • Processes contaminated soil, sediments, sludge, or water in a controlled system.
    • Creates a three-phase mixing environment (solid, liquid, gas) to accelerate rates of remediation
    • Utilizes water slurry, indigenous microbes, to degrade pollutants

    Phytoremediation

    • Use of plants to remove or stabilize contaminants
    • Plants grow in polluted soil, enabling them to extract contaminants from the soil or up into the stem/leaves
    • Harvested plant material can be removed and disposed of or burned

    Biolixiviation (Metal Recovery)

    • Bacteria extract metallic elements from minerals by solubilizing them.
    • Used for low-grade minerals
    • Microorganisms are autotrophic (use CO2) or heterotrophic (use organic carbon)
    • Examples of Used Microorganisms: Thiobacillus ferrooxidans, Leptospirillium ferrooxidans, Thiobacillus thiooxidans, Sulfobacillus thermosulfidooxidans

    Biosorption

    • General term for processes recovering metals using biomass
    • Employs raw biomass material for sorption, performance depends on biomass type and solution chemistry
    • Modifiable biosorbents can enhance sorption capacity

    Types of Biosorbents

    • Algae, bacteria, fungi, yeasts, and plants

    Mechanisms of Biosorption

    • Physical interactions like electrostatic attractions, complexation, precipitation, or covalent bonds
    • Redox reactions by functional groups in the biomass (e.g., carboxyl, hydroxyl, phosphate)

    Biosorption by Algae

    • Algae contain high quantities of biopolymers with good metal adsorption capabilities
    • Wide variety of algae types (red, brown, green)
    • Contains polysaccharides (cellulose, xylan), uronic acids (alginate acids), sulfated polysaccharides (agarose, agaropectin, carrageenan), carboxyl, sulfonic, and hydroxyl groups
    • Alginate comprises a significant portion of the dried algae and is important in metal adsorption

    Biosorption by Fungi and Yeasts

    • Fungi and Yeasts contain chitin (essential component of cell walls)
    • Utilizes chitin synthase activity

    Biosorption with Bacteria

    • Active Biosorption: Metal-bacteria interactions (living/active cells), includes precipitation, intracellular accumulation, oxidation-reduction, and methylation-demethylation processes
    • Passive Biosorption: Physical interactions and reactions, includes complexation and sorption onto the bacterial cell wall

    Bacteria

    • Reactive surfaces with sorption sites
    • Neutral pH, net negative charge
    • Cell wall components (Gram (+): peptidoglycan, Gram (-): outer membrane rich in hydroxyls, carboxyls, phosphates, and amines)

    Factors Influencing Biosorption

    • Medium physicochemical properties (pH, temperature, ionic strength, dissolved oxygen, other metallic cations, ligands)
    • The Metal: size to charge ratio, ionic radius, valence, metal speciation, concentration, solubility
    • The Nature of Biosorbent: composition, concentration

    Microbial Sulfate Reduction

    • Primary process under anaerobic conditions, involving several bacteria like Desulfotomaculum
    • Processes under strictly anaerobic conditions
    • Neutrophillic, Optimal pH around 7
    • Requires electron donors (e.g., lactate, formate, acetate, or H2)
    • Performs complete or incomplete substrate oxidation
    • Forms hydrogen sulfide, facilitating metal precipitation via insoluble solid production

    Precipitation of Metals as Sulfides

    • Metal precipitation depends on stability of formed solid
    • FeS is generally more stable than MnS

    Intracellular Accumulation

    • Metals are initially combined with the cell wall
    • Then transported inside the cell

    Iron Oxidation-Reduction

    • Alters the oxidation state
    • Solubilizes Fe(II), oxidizes to Fe(III, more soluble form)
    • Microbial reduction of Fe (III) contributes to the formation of Fe (II) phosphates

    Phytoextraction

    • Hyperaccumulators absorb contaminants through roots, concentrate in leaves, etc.
    • Harvested material is removed from the environment

    Phytotransformation

    • The uptake of organic contaminants from soil, sediments, or water, and subsequent transformation to a more stable/less toxic/mobile form.
    • Examples include reduction of chromium from hexavalent to trivalent.

    Phytostabilization

    • Plants reduce mobility and migration of contaminated soil
    • Leachable constituents are adsorbed and bound into the plant structure
    • Plants form a stable mass that prevents contaminants re-entering the environment

    Phytodegradation

    • Breakdown of contaminants within the rhizosphere
    • Primarily due to proteins and enzymes from plants or soil organisms (e.g., bacteria, yeast, fungi)
    • Plants provide nutrients to microbes for growth, microbes offer healthier soil environment.

    Rhizofiltration

    • Water remediation technique using plant roots to uptake contaminants.
    • Used to reduce contamination in wetlands and estuary areas

    Limitations of Bioremediation

    • Contaminant type & concentration
    • Environmental conditions (soil type, proximity of groundwater)
    • Nature of organism
    • Cost-benefit ratios (cost vs environmental impact)
    • Applicability (not all surface areas are suitable)
    • Length of time for the bioremediation process

    Advantages of Bioremediation

    • Minimal exposure to the contaminant for workers
    • Long term benefit for preventing public health issues
    • Cost effective compared to other methods
    • Onsite process, no need to transport materials
    • Uses natural processes
    • Perform degradation in an acceptable time frame

    Disadvantages of Bioremediation

    • Cost overruns
    • Failure to meet targets
    • Poor management
    • Environmental impact
    • Release of contaminants
    • Difficult to estimate completion times and varies by site.

    Pollutants in Soil and Aquatic Bioremediation

    • Organic compounds (hydrocarbons, pesticides, insecticides, herbicides, fungicides, organometallics, etc.)
    • Metals (Essential: small amounts; non-essential: heavy metals in trace amounts in biosphere)

    Biodegradation

    • Complete oxidation or mineralization
    • Complete biodegradation: decomposition, basic elements
    • Partial biodegradation: formation of less complex intermediates
    • Biotransformation: transformation into a stable molecule

    Factors Affecting Biodegradation

    • Biological factors (microorganism growth, metabolism, acclimatization, growth kinetics)
    • Environmental factors (physical conditions, chemical factors, sorption, bioavailability)
    • Chemical factors (structure, function, sorption, bioavailability, cometabolism, recalcitrance, toxicity)

    Factors Affecting Bioremediation

    • Factors governing microbial activity (redox potential, pH, temperature, water content, nutrients)
    • Factors governing mobility (Macroscopic Heterogeneities: faults, fractures, stratification, soil structure, soil texture, Adsorption and desorption factors [including clay and organic matter])

    Lack of Biodegradation

    • Lack of nutrients
    • Limiting environmental conditions (temperature, humidity, oxygen)
    • Presence of toxic substances at high concentrations.
    • Compounds present at low concentrations
    • Non-bioavailable compounds
    • Issues with bioavailability (sorption, presence in non-aqueous solution, pollutants' state, complexity, solubility)

    Recalcitrant Pollutants

    • Compounds slow or impossible to eliminate biologically
    • Examples: polymers (PVC, Teflon), polychlorinated organic compounds (PCB, DDT), pentachlorophenol
    • Resistance to microbial degradation, frequently encountered in natural substances like lignin, humic acids.

    Classification of Recalcitrant Compounds

    • Compounds resistant to microbial attack, metabolized very slowly or not at all
    • Compounds rapidly degraded in dense cultures of specific microbes.

    Conditions for Biodegradation

    • Enzyme for substrate degradation must exist
    • Microbes capable of using/producing the enzyme must be present in the same environment
    • Molecule to be degraded must be available to the microbes
    • Substrate must penetrate the microbes cell membrane
    • Enzyme induction conditions (sufficient substrate concentration or presence of another substrate allowing cometabolism) must be met.
    • Favorable environmental conditions for microbial growth

    Half-Life and Persistence of Pollutants

    • Time required for the biodegradation of 50% of the pollutant
    • Depends on pollutant properties, environmental conditions (aerobic/anaerobic conditions, microbial activity, temperature, pH)

    Microbial Depollution Mechanisms: Degradation

    • Degradation: Breakdown of substrate, e.g., H2O, CO2, CH4, H2, chloride, acetate.
    • Mineralization: Assimilation of substrate, e.g., CO2

    Microbial Depollution Mechanisms: Cometabolism

    • Unexpected conversions due to low enzyme specificity.
    • Substrate may not trigger enzyme synthesis unless present in sufficient quantities to activate the appropriate enzymes
    • Substrate conversion may lead to unusable compounds
    • Degradation of a xenobiotic may require reduction reactions, where electrons must come from another substrate.

    Detoxifying Transformations

    • Modifications to molecules to make them inactive, may be minor or significant
    • Examples provided (e.g., hydrolysis, hydroxylation, dehalogenation, demethylation, methylation, reduction of a NO2 function, etc., to remove halogen, converting nitrile to amide, opening benzene rings)

    Metabolism of Decomposers

    • Food particles transported to surface and adsorbed onto cell membrane via diffusion.
    • Pre-digestion of food particles facilitated by exoenzymes or surface enzymes.
    • Molecules’ dimensions reduced.
    • Permeation of food molecules across the cell membrane.
    • Degradation of molecules

    Cometabolism of TCE (Trichloroethylene)

    • Breakdown of TCE through a multi-step process, facilitated by a specific methane mono-oxygenase in the presence of methane.

    Aromatic Hydrocarbons

    • BTEX: Benzene, Toluene, Ethylbenzene, and Xylenes.
    • PAHs: Polycyclic aromatic hydrocarbons (more than two fused aromatic rings).
    • Biodegradation of aromatic compounds (2 main steps): Hydroxylation (incorporation of hydroxyl ion, reaction catalyzed by monooxygenase/dioxygenase), and cleavage of aromatic ring (catechol is cleaved by dioxygenase).
    • The hydroxylations are initial reactions in metabolism, with oxygenases.

    Oxygenases

    • Involved in initial hydroxylations of aromatic rings
    • Divided into 2 groups
    • 1-Hydroxylation group: these enzymes add one oxygen atom to the substrate while reducing a second oxygen atom to water
    • 2-Dioxygenase group: these oxygenases add two oxygen atoms without reduction to water.
    • Examples include the hydroxylation of benzoic acid and to catechol

    Ortho and Meta Cleavage

    • Important reactions in the degradation of catechol and protocatechuic acid.
    • Lead to the formation of other necessary molecules, eventually breaking down and releasing carbon elements to be used in the Krebs cycle.

    Aromatic Compound Biodegration of Benzene

    • Benzene's hydroxylation to catechol and subsequent cleavage are important steps in aerobic degradation.

    Dehalogenation mechanisms of Haloaromatic Compounds

    • Oxidative, Hydroxylating, Reductive dehalogenation

    Polyaromatic Hydrocarbons (PAHs)

    • Multiple associated rings, often resistant to biodegradation, significant environmental issues
    • Produced through combustion of fossil fuels or natural processes (e.g., decomposition of lignin)

    Factors Affecting PAH Degradation

    • Number of rings
    • Number/position of Substituents
    • Degree of Saturation

    Insecticides

    • Example: DDT and analogues
    • DDT analogues result from degradation
    • A major reaction involves intermediates like DDE

    Organophosphorus Compounds

    • These compounds include common insecticides (malathion, parathion) that are less persistent compared to organochlorines.
    • Metabolized by bacteria like Pseudomonas, Arthrobacter, Streptomyces, Thiobacillus and fungi (Trichoderma).
    • Several degradation products.

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Related Documents

    Environmental Biotechnology PDF

    Description

    Test your knowledge on bioremediation techniques, including the role of biopiles, types of reactors, and the processes involved in phytoremediation. This quiz covers essential concepts related to the degradation of aromatic compounds and the effectiveness of biotechnological solutions. Challenge yourself and see how well you understand these critical environmental processes.

    More Like This

    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser