Transcript Water Pollution

Biological Remediation of Land and
Water
Naz Mina Mert
Zuhal Ozcan
Inanc Pastirmaci
Oya Tekbulut
Outline
1. Land pollution
2. Bioremediation of land
3. Water pollution
4. Bioremediation of water
Bioremediation of Land
What is bioremediation?
• The process of cleaning up contaminated
sites using microorganisms to remove or
degrade toxic wastes and other
pollutants from the environment.
• Bioremediation can occur naturally or
can be encourage with addition of
microbes and fertilizers.
• Ex Situ:the removal of the contaminated
material to be treated elsewhere.
• In Situ: treating the contaminated
material at the site.
• Dominantly used organisms:
–Bacteria (anearobic and aerobic)
–Fungi
Suitable conditions for
bioremediation
• Sufficiently large bacteria population
• Presence of electron acceptors
• Presence of nutrients (nitrogen and
phosphorus)
• Chemicals not toxic for bacteria
• Sufficient source of carbon for bacterial
growth
Bioremediation
techniques:
Land Farming
• Ex Situ
• Contaminated soil is spread over a prepared
bed along with some fertilizers and
occasionally rotated.
• It stimulates the activity of bacteria and
enhances the degradation of oil.
Composting
• Ex Situ
• Piling of contaminated soil organic substances
such as agricultural wastes
• Development of a rich microbial
population.
• Increase in temperature of the pile.
Stimulation of microbial growth by added
nutrients.
• Eventually biodegredation.
Bioventing
• In situ remediation technology.
• Adding of oxygen in unsaturated zone by
pressing.
Biopiling
• Ex situ version of soil bioventing.
• Soil is mixed with additives and placed onto
suitable site.
• Ventilation device is installed during piling.
Phytoremediation
• Plants and trees are planted.
• Their roots absorb contaminants from
groundwater over time, and are harvested
and destroyed.
• For ex: cottonwood for Hg
Biostimulation
• In situ
• modification of the environment to stimulate
existing bacteria.
• the process of adding nutrient, electron
acceptor and oxygen to stimulate.
• Additives are usually added to the subsurface
through injection wells.
Bioaugmentation
• In situ
• The addition of a group of indigenous
microbes or genetically engineered microbes
to treat the contaminated soil.
Bioremediation of Heavy Metals
• Works through the adsorption of metal
molecules to bacterial cells.
• Transformation to nontoxic compounds
(CO2 and H2O) is not possible.
• Transformation to less toxic compounds
occur.
Question:What are the suitable
conditions for bioremediation?
• Sufficiently large bacteria population
• Presence of electron acceptors
• Presence of nutrients (nitrogen and
phosphorus)
• Chemicals not toxic for bacteria
• Sufficient source of carbon for bacterial
growth
Water Pollution
What is water pollution?
• a global problem
• Varies in magnitude and type of pollutant
• Developing countries
– lack of disease-free drinking water
Eight categories of water pollution
•
•
•
•
•
•
•
•
Sewage
Disease-causing agents
Sediment pollution
Inorganic plant and algal nutrients
Organic compounds
Inorganic chemicals
Radioactive substances
Thermal Pollution
Sewage
• The release of sewage into water results in
several pollution problems.
1. Because of the disease-causing agents in it, sewage
poses a threat to public health.
2. Enrichment: the fertilization of water due to the
presence of high levels of plants and algal nutrients,
i.e. nitrogen and phosphorus.
–
Cellular respiration requires the presence of oxygen , fishes and
other organisms also use oxygen. In aquatic ecosystems
containing high levels of sewage, decomposition of
microorganisms use up most of the dissolving oxygen, leaving
little for aquatic animals. -> Fishes and other animals die or
migrate if condition is harsh
Sewage (cont’d)
3. Another serious
environmental problem
that sewage generates is
oxygen demand. Organic
wastes including sewage
are measured in terms
of their biological
oxygen demand and it is
expressed as milligrams
of dissolved oxygen per
liter of water. A large
amount of sewage
produces high BOD
which decreases the
water of dissolved
oxygen and
consequently
compounds with
unpleasant odor are
generated, reducing Figure 1: The dissolved oxygen in the figure above,
directly influences the organisms living inside the river.
water quality.
The curve for BOD (biological oxygen demand) is also present in the above
picture.
Disease-causing agents
• Infectious organisms causing diseases
– i.e. cholera, infectious hepatitis, typhoid
• Generated from the waste of infected
individuals
• Municipal wastewater usually contains many
bacteria, viruses, and other agents that lead to
diseases
• Rare in highly developed countries, major
cause of death in less developed countries
Sediment Pollution
• Sediments are not necessarily pollutants, they are mostly important for
providing essential nutrients to wetland areas and in regenerating soils in
agricultural areas.
• Sediment pollution occurs when excessive amounts of suspended soil
particles settle out and accumulate on the bottom of the water.
• Results from erosion of agricultural lands, strip mines or construction
• Reduces light penetration, covers aquatic organisms, brings insoluble toxic
pollutants into the water, and fills in waterways
– Reduction in light penetration lessens the ability of producers to
photosynthesize, which might cause a decrease in the number of the
organisms
Inorganic Plants and Algal Nutrients
• Inorganic plants and algal nutrients are chemicals such as
nitrogen and phosphorus that stimulate the growth of
plants and algae
• They are essential for the normal functioning of healthy
ecosystems but are harmful in larger concentrations
• Source: animal and human wastes, plant residues,
atmospheric deposition
• Encourages excessive growth of plants and algae ->
disrupts the balance between producers and consumers
• Bad odor
• Encourages enrichment
Organic Compounds
• Organic compounds: contain C atom
– i.e. sugars, amino acids, oils
• Found in: water, human-produced chemicals
• Some organic compounds seep from landfills
into surface water and groundwater
• Some pesticides leach downward though the
soil into the water
• Sometimes industries dump organic
compounds directly into waterways
Radioactive Substances
• Contain atoms of unstable isotopes that
spontaneously emit radiation
• Reach water through mining and processing of
radioactive substances, such as uranium and
thorium
• Various industries use radioactive substances
and radiation can escape from these facilities
and pollute water
Thermal Pollution
• Thermal water occurs when heated water produced during
certain industrial processes is released to waterways
• Industries use water to remove excess heat from their
operations and then the water is allowed to cool a little and
returned to waterways when it is still warm
• Due to the high temperature, the waterway is warmed
– Reproductive cycles, digestion rates, and respiration rates of
organisms might change due to the temperature change
– Chemical reactions, such as decomposition of wastes, occurs
faster, depleting the water of oxygen
– Less oxygen dissolves in warm water
Both have serious consequences in aquatic life:
- Fishes require more food to maintain body weight,
-Shorter life spans, smaller populations
Question
• What can individuals do for prevention of
water pollution? Do you believe it would
change anything?
Answer
• Although individuals produce little water pollution, the
collective effect of municipal water pollution, even in a
small neighborhood, can be quite large. Some of the
things that individuals can do to protect surface waters
and groundwater from pollution:
– Drive less. Air pollution emissions from cars eventually get
into water. Also, toxic metals and oil by-products deposited
on the road by cars are washed into surface waters by
precipitation
– Pick up pet waste and dispose it in the garbage or toilet
– Do not throw unwanted medicines down the toilet
Bioremediation of Water
Figure retrieved from http://www.algaeindustrymagazine.com/algal-bioremediation-withhydroentia
Wastewater Treatment
• Removal of human sewage
– Agents stimulating bioremediation of household wastes
• Bacteria rich in degrading enzymes
• Wastewater treatment plants
– a mudlike material: sludge
– flowing water: effluent
– Oxidation of organic materilas in the effluent
• Candidatus ‘Brocadia anammoxidans’  degradation of ammonium
Septic-tank disposal systems
Wastewater Treatment
Wastewater treatment plants
– Primary Treatment
• Removes around 30 – 40 % of BOD (v)
– Secondary Treatment
• activated sludge recycled
– Advanced Wastewater Treatment
• eg. phosphates and nitrates, heavy metals,
organic chemicals
• Sand filters, corabon filters
• Good water quality
Figure retrieved from Botkin & Keller (2011).
Wastewater Treatment
Septic-tank disposal systems
When any central sewage system or wastewater treatment facility is not available
Common problems:
Failure to pump out the septic tank whilst full of
solids
Poor soil drainage
Figure retrieved from Botkin & Keller (2011).
Groundwater Cleanup
•
Combination of in situ and ex situ techniques
Figure retrieved from Thieman & Palladino
(2009).
Figure retrieved from Fingerman, et al.
(2005).
http://www.youtube.com/watch?v=vENEpRUhbms
Figure retrieved from Fingerman, et al.
(2005).
Figure retrieved from Malik. (2004).
Figure retrieved from Malik. (2004).
Figure retrieved from Malik. (2004).
Figure retrieved from Davis, et al. (2003).
Question: In their research, Romera, et al. (2007) shows that Chondrus crispus, a type of
red alga exhibits uptake of various metals from aqueous solutions in different pH values (see
the figure below). A scientist would like to propose a strategy for the identification of
Chondrus crispus which may play role in degrading an efficient metal within this pH range.
What would be the best choice and what can be her strategy ? (Initial conditions are
assumed to be kept constant and ideal).
Figure retrieved from Romera, et al.
(2007).
Answer: The values suggest that within the range of 4 – 5 (pH), Cu is observed to show the
optimum sorption activity. This may be the sign that the cells of the species are capable of the
degradation of Cu. Further experiments should be done to check with the biomass capacity of the
species and see if it is possible to yield sustainable biosorption activity.
References
Boktin, D. B. & Edward, A. K. (2011). Water pollution and treatment. In Environmental Science, pp. 414-417.
Wiley.
Davis, T. A., et al. (2003). A review of the biochemistry of heavy metal biosorption by brown algae. Journal of
Water Research, 37, 4311-4330.
Fingerman, et al. (2005). Bioremediation of Heavy Metals Using Microorganisms. In Bioremediation of
Aquatic and Terrestrial Ecosystems, pp. 97-100. Science Publishers: Enfeld.
Malik, A. (2004). Metal bioremediation through growing cells. Environment International, 30, 261-278.
Peter H. Raven ,Linda R. Berg, David M. Hassenzahl (2001) Environment
Richard T. Wright, Dorothy F. (2008) Boorse Environmental Science
Romera, E., et al. (2007). Comparative study of biosorption of heavy metals using different types of algae.
Journal of Bioresource Technology, 98, 3344-3353.
Thieman, W.J. & Palladino, M.A. (2009). Bioremediation. In Introduction to Biotechnology, pp. 218-221.
Pearson.
William J. Thieman Micheall, A. Palladino Third Edition Inroduction to Biotechnology
http://www.theinnovationdiaries.com/wp-content/uploads/2011/12/how-does-water-pollution-affect-humans.jpg
http://waterdesalinationplants.com/sewage-treatment/
http://gtms1319.wordpress.com/
http://www.sherpaguides.com/georgia/chattahoochee/chattahoochee_in_peril/