bioremediation Flashcards
what is bioremediation
the use of living organisms to degrade environmental pollutants through waste treatment
what is bioremediation used for
contaminated ground water and soil
what is the main process of bioremediation?
microbial dégradation and minéralisation of pollutants
pollution has been an increasing problem since….?
the second half of 20th century
why is there an increase in pollution
with the introduction of novel substances
what are the novel substances
pesticides herbicides fungicides
plastics; oil
heavy metals etc
what is resistant to biodegradation
recalcitrant compounds
why are recalcitrant compounds resistant to biodegradation
unusual substitutions - not recognised by existing enzymes
most common is chlorine aromatic rings
what are polychlorinated biphenyls (PCB)
usually oil, viscous liquid
what are the properties of polychlorinated biphenyls
high chemical resistance
low electric conductivity
high boiling point
generally inert
what can polychlorinated biphenyls be used for
insulator
coolant
fire retardants
paper industry
polychlorinated biphenyls were widely used until banned in
1979
why were polychlorinated biphenyls banned
cause nausea, eye/nose irritation, headache - also damage immune system and are teratogenic and carcinogenic
when does the resistance to biodegradation of recalcitrant compounds begin
at a molecular weight of 500
how much oil pollutes the oceans each year
10 X 10^6
there is a complex mixture of what in crude oil
aliphatic and aromatic hydrocomounds
how does the oil enter the ocean
spillage and disasters
what is the best removal method of oil from ocean
skim off surface
addition of detergent (largely cosmetic )
best candidate for treatment : Bioremediation
what is the approach of bioremediation
create favourable conditions for development of naturaly occurring biodegraditative organisms
what is biostimulation
add specific biodegradative organisms (natural or manufactured)
what are the two methods of treatment of bioremediation
treat contaminated area in situ
if possible remove to special treatment site (ex situ)
name the two types of ex situ bioremediation
slurry phase and solid phase
describe the slurry phase
contaminated soil mixed with water in bioreactor
aerated, nutriece added and mixed
describe the solid phase
land farming
biopics
compositing
what is composting
degradation by microorganisms at raised temperature
what temperature is composting usualy carried out at
55-65
describe composting
heat produced by microorganisms
- decrease of bulk density and supply of organic carbon
- spreading into long rows
- rows are regularly turned and mixed
- monitoring of PH, temperature and contaminant concentration
what is bioagumentation
methods of producing microorganisms with degradative powers
name the two types of bioaugumentation
accelerated evolution
genetic engineering
describe accelerated evolution
grow organism in low conc of product.
- and higher conc of similar but degradable product
- gradually increase conc of target compound and reduct conc of similar one
- process selects for spontaneous mutations organisms with much increased ability to utilise target compounds
how can mutation rates be increased in accelerated evolution
use of uv radiation or chemical mutagens
e.g - acridine orange
what else can you use for acellerted evolution
may also use genome shuffling
describe the organisms needed in the polychlorinated biphenyls process
more organisms needed than one
organism 1: remove cl atoms
Organism 2: opens benzene ring
Organism 3: produces acetaldehyde
genetic engineering used to place genes from organism 1-3 onto plasmid single organism capable of metabolising PCB
