Environmental Biotech chp 7, 8, 9 Exam Study

Chp 7 - Xenobiotics, Chp 8 - Bioremediation, Chp 9 - WRF Bioremediation

xenobiotic compound

man-made synthetic compound not found in nature

Biomagnification

raise in concentration of xenobiotic compounds as it passes through the levels of the food chain

recalcitrant

does not degrade further

glyphosate

non-selective herbicide used to kill weeds, blocks essential enzymes to synthesize amino acids

PFA

found in blood of most people and animals

Polychlorinated Biphenyls (PCB)

compounds with two covalently linked benzenes, halogens end up substituting for H

used as transformers and heat exchange fluids

biologically and chemically inert

Synthetic Polymers

plastics

recalcitrate due to molecular size and water insolubility

Alkylbenzyl sulfonates

surface acting detergents

sulfonate end resists microbial degredation

non-polar alkyl end recalcitrant if branched

Oils

recalcitrant due to water insolubility + toxicity

variable mixture of hydrocarbons + other organic compounds

Petroleum or crude oil

flammable, complex, variable mixture in liquid state

Percentages of petroleum

83-87% C, 10-14% H, trace N, O, and S

Paraffin

petroleum fraction

has alkane series

Naphthenes

petroleum fraction

includes cycloalkanes

Organochlorides or chlorinated hydrocarbons

degrade slowly and persist in ecosystem for long time

contain at least once chlorine atom

Ex: DDT

Organophosphates

react with acetylcholinesterase + other enzymes and disrupts nerve impulses

preservative toxic effect to flora or fauna, multiple exposures amplify toxicity

contains phosphorus bonded to C atoms of organic radicals

EX: malathion

Carbamates

phenols or esters

closely related to organophosphate compounds in way of action / resistance development

Pyrethroids

chemical compound developed to mimic pyrethrum (natural pesticide)

used against domestic pests

degradable + act as sodium channel modulators

soil pollution

often result from range of anthropogenic activities

contamination can be correlated with degree of industrialization and intensity of chemical usage

bioremediation

a managed or spontaneous practice in which microbial processes are used to degrade of transform contaminates to less toxic or nontoxic forms, thereby remediating or eliminating environmental contamination

What are the most active organism participating in the biodegradation of organic waste

bacteria

Fungal bioremediation

degraders of biopolymers

WRF used in land applications

can be adsorbent of heavy metals

Algal bioremediation

used for the removal of organic matter and nutrients from waste exposed to light energy

Microbial Degradation

natural populations exist in dynamic equilibrium that can be altered by modifying the environmental conditions, like nutrient availability

relies more on indigenous populations

degradation

compound transformed into simple products, sometimes mineralisation

Conjugation

Formation of complex or addition reactions to more complex compounds

Detoxification

conversion to non toxic compound(s)

Activation

compound converted into a more toxic compound

Biostimulation

add nutrients to promote in situ growth

natural populations that are exposed to the polluting compounds can develop ways to degrade the pollutant

growth of these microbes are nutrient limited

Bioaugmentation

removal of microbial samples from polluted site followed by enrichment of useful microbes in bioreactor cultivation then re-inoculation of large quantities of the microbes into the contaminated site

some companies that do this claim to increase the rate of biodegradation of oil pollutants

Problems of bioaugmentation

native microbes fully adapted to specific environment

introduced / foreign microbes must be able to survive environment and compete with native microbes

added inoculum must remain in close contact with pollutant

Genetically Engineered Microorganisms (GEM)

these microbes are able to degrade organic pollutant molecules that unmodified microbes cant

legal/ethical/other problems concerning release into environment

none have been tested outside of laboratory

anaerobic degradation of chlorinated compounds

reductive declorination

aerobic degradation of chlorinated compounds

aerobic dechlorination

Uranium contaminated soil bioremediation

bacteria reduce U6+ to U4+

first is water soluble, second is not

Uranium trapped in reduced form and NOT removed

Organic pollutants (Hydrocarbons / PAHs)

microbes can completely degrade these to CO2

prokaryotes have been used for several major contamination events

aerobically degraded by bacteria, fungi, cyanobacteria, and green algae

Aerobic Hydrocarbon Metabolism

oxygenases catalyze incorporation of O2 into organic/inorganic compounds

Monooxygenase

incorporate one oxygen atom with the other reduced to H2O, often NADH-/NADPH- dependent

Dioxygenases

incorporate both oxygen atoms

Aliphatic Hydrocarbon Metabolism

degraded by denitrifying and sulfate reducing bactera

Anoxic hexane metabolism in BTEX well studied

Aromatic Hydrocarbon Metabolism

anaerobic respiration degrades these via ring reduction

Phytoremediation

degradation of xenobiotic compounds using plants which can degrade, extract, or immobilize contaminants in soil and water

start on WRF slides to finish