1. sub - topic B problems with profit and waste
Biotechnology
sub - topic B problems with profit and waste
Part 1 SEWAGE

2. The effect of untreated sewage on rivers
Rivers contain bacteria.
These bacteria use oxygen during aerobic respiration.
Untreated raw sewage contains organic material ( faeces ,food fragments, soap etc)
Bacteria feed on this organic waste, breaking it down to release energy.
They use this extra energy to multiply.
The larger numbers of bacteria use up more oxygen
Oxygen supply is depleted (reduced)
Animals like fish die due to oxygen starvation

3. The breakdown of sewage by bacteria releases Nitrates and Phosphates
Nitrates and phosphates are used by green algae to grow fast and cover the surface of the river/lake (algal bloom)
The algae stop light getting to lower aquatic plants, which then die -- the oxygen they provide during photosynthesis is no longer available
Organic waste on river bed broken down by bacteria to release foul smelling gases and rotting materials.

4. Algal bloom Raw sewage 4 Fish die due to lack of oxygen 1 6 3
Nitrates and phosphates 6 3
Water has little oxygen 5
Bacteria feed on raw sewage
Smelly gas 2 8
Anaerobic bacteria digest sewage to form methane gas 7

5. Water borne diseases
Untreated sewage can contain micro- organisms causing ;-
Dysentery, typhoid and cholera.
In Britain sewage is treated in a Sewage treatment works to make it safe.
Natural disasters ;-
earthquakes can fracture underground pipes and cause raw sewage to mix with drinking water.

6. Treatment of Raw Sewage
This is done at a Sewage Treatment works
Material entering the sewage works is firstly screened to remove large objects eg. Rags and grit.

7. Primary Settlement
Once screened, the sewage is passed to a primary settlement tank where it stays for 6 hours to separate solid from liquid waste.

8. Primary settlement tank

9. Aerobic breakdown of sewage
Secondary treatment
Aerobic breakdown of sewage
Breakdown of sewage by anaerobic bacteria will always leave some sewage material untreated (unsafe).
Aerobic bacteria, however will give complete breakdown, leaving only carbon dioxide and water (safe).
Sewage + oxygen carbon dioxide + water
aerobic bacteria
Sewage contains a range of materials requiring particular micro-organisms for their breakdown, therefore a range of micro-organisms are needed to break it down fully.

10. Oxygen can be provided in two ways;
Biological filtration
The sewage is trickled through filter beds and is broken down by bacteria coating the stones. Air spaces between the stones provide the oxygen.
B. Activated sludge process
The sewage is mixed with activated sludge (sewage with sewage – eating bacteria added to it). Oxygen is then supplied by bubbling compressed air through the mixture.
Primary settlement
sludge

11. Biological filtration

12. Activated sludge tank

13. The sludge collected is reused in the activated sludge process.
The treated sewage is then passed to final settlement tanks.
Here, activated sludge present in the mixture from either process is allowed to settle out.
The sludge collected is reused in the activated sludge process.
The purified effluent is released into the river.

14. Anaerobic breakdown of sewage
Sludge from primary settlement and activated sludge from the final settlement tank are combined and kept under anaerobic conditions, where bacteria break them down to produce methane gas (fuel).
Waste from this process is either dumped at sea or treated to kill pathogens, and then offered to farmers for spraying on fields as fertiliser.

15. Anaerobic digester

17. Treatment Notes Sewage Treatment -- Summary
Screening / grit removal
Grit, stones + rags are removed by a filter
Primary Settlement
Solids are separated from liquid waste
Secondary treatment
Aerobic breakdown of sewage by a range of micro organisms
Biological filtration – oxygen provided by air spaces between stones
Activated sludge process – oxygen provided by compressed air
Final Settlement
Activated sludge remaining from secondary treatment settles out before clean water released
Sludge Treatment
Anaerobic breakdown of sludge by micro organisms to produce methane gas
Sludge Disposal
Pathogens killed then sludge dumped at sea or sprayed on fields as fertiliser
Sewage + oxygen carbon dioxide + water
A range of micro-organisms are needed to break down sewage because
It contains a range of materials which cannot be broken down by only one type of micro organism

18. Safe Handling of Microbes

19. Airborne microbes Culturing Microbes
Fungal spores and bacteria can travel in the air and land on surfaces.
Floors in hospitals ,schools etc are washed regularly to minimise the spread of any harmful microbes
Culturing Microbes
We can grow colonies of microbes using a nutrient gel or Agar in a petri-dish.

20. Working with Microbes
We already know how microbes can help in the manufacture of food and drink.
Also that some microbes cause disease if they enter the bodies of living things.
It is obviously important when working with microbes in the lab to adopt “safe practice”.
This avoids unwanted growth of microbes and disease.

21. Unwanted Microbes
Contamination is the presence of unwanted, possible harmful microbes.
To prevent contamination all equipment must be clean and sterilised.
This is done in an autoclave, where equipment is heated to very high temperatures by steam (boiling is not enough).

22. Safe Practice
The bench is thoroughly cleaned with disinfectant and hands are washed.
Sterile (very clean) equipment is collected:
Petri dishes with agar food jelly
Plating loop
Culture of bacteria
Bunsen burner

23. Working close to the hot bunsen flame the loop is heated till red hot then allowed to cool.
This kills organisms on the loop

24. A sample of bacteria is collected from the culture bottle
A sample of bacteria is collected from the culture bottle. The culture bottle is carefully opened and closed next to the flame.

25. Working close to the flame the loop is now gently rubbed over the surface of the agar jelly in the dish.

26. The loop is again heated till red hot and allowed to cool.
The dish is sealed, then labelled and placed in an incubator.
Lid
Joe Bloggs microbeX 25/02/10
Label placed on bottom of dish
Tape

27. Bacterial Culture showing growth after incubation

28. Summary Precautions Reasons Hands washed before and after work
Remove bacteria picked up from the environment / remove any picked up during lab work
Benches swabbed with disinfectant
Remove bacteria and spores from benches
Lab coat should be worn
Prevent contamination of clothes by bacteria
Use only safe bacterial cultures
Other sources, e.g. air, soil etc. may contain pathogenic bacteria
Autoclave all equipment
Heating in an autoclave kills all foreign bacteria
Work beside bunsen, flaming loops and necks of culture bottles
Prevent entry of foreign bacteria and kill cultured bacteria on loops etc.
Incubate bacterial cultures below body temperature
This discourages the growth of pathogens which grow best at 37oC
Autoclave all equipment after use, and cultures before disposal
Kill all bacteria in case any pathogens have appeared

29. Summary

30. Precautions taken during Manufacturing Processes
CREDIT
In most industrial processes involving microbes, the biggest danger is foreign bacteria or fungi getting into the process, rather than the cultured microbe escaping.
Some bacteria and fungi make resistant spores when faced with adverse conditions e.g. extreme drought, heat, pH etc.
The thick coat they produce only disintegrates when conditions become favourable again.

31. CREDIT
If these get into the manufacturing process
they may cause;
A health hazard – they may be pathogenic.
Financial loss if a whole batch of product is contaminated.
To prevent this, all equipment (fermenters, pipework etc. is frequently steam-cleaned.
The high temperature of the steam can kill the spores.

32. Decay and Recycling

33. Decay CREDIT Bacteria and fungi can breakdown organic matter
This process is called Decomposition.
Decomposition is a natural process.
The bacteria or fungus obtain energy from breaking down the organic material

34. Recycling
CREDIT
Decomposers breakdown dead bodies and waste materials to organic compounds.
The organic compounds contain Mineral salts that are released into the soil.
Plants use these Mineral salts to grow
Apart from Mineral salts the elements Carbon and Nitrogen also have to be recycled

35. Denitrifying bacteria
Nitrogen Cycle
Denitrifying bacteria
Atmospheric nitrogen
Nitrogen is used by animals and plants to make protein
Nitrogen-fixing bacteria (in root nodules)
Lightning storms
absorbed through roots
Soil nitrates
Plant protein
eaten
Animal protein
Nitrifying bacteria
death
death
Nitrites
Faeces + dead remains
Nitrifying bacteria
Ammonium compounds
Decomposers (bacteria+fungi)

36. Root nodules
CREDIT
Plants like clover, peas and beans have root nodules containing nitrogen fixing bacteria on the roots.
These bacteria take nitrogen gas from the air and change it into nitrates in the roots.
the clover uses the nitrates to make proteins.
Farmers like clover to grow in a field to replace the supply of natural nitrates in the soil

37. There are three main processes;
Carbon Cycle
CREDIT
There are three main processes;
Photosynthesis - uses carbon dioxide
Respiration – releases carbon dioxide
Combustion – releases carbon dioxide

38. respiration by decomposers photosynthesis
CREDIT
Carbon Cycle
Atmospheric carbon dioxide
respiration
respiration
respiration by decomposers
photosynthesis
eaten
Carbon compounds in animals
Carbon compounds in plants
death
death
combustion
Carbon compounds in dead organic matter (humus)
Carbon in fuels e.g. coal

39. Upgrading Waste

40. Food and Fuel from Waste
Many manufacturing processes produce waste products.
These waste products can be upgraded -- fed to microbes which convert them to products which are useful to people and other animals.
Advantages of upgrading waste;
Unwanted waste products can be converted into products with a high energy content (fuels), or a high protein value (foods).
CREDIT
Savings on waste disposal and environmental pollution.

41. Examples;

42. Fuels from Microbes Fermentation is an energy releasing process.
This is carried out by some microbes in the absence of oxygen.
Alcohol and methane gas are products of fermentation, they are fermentation fuels.
Fossil fuels are NON RENEWABLE
Fermentation fuels are RENEWABLE

43. 1. Fermentation of Manure by bacteria To produce methane gas
When microbes feed on fresh manure, they produce methane gas ( BIOGAS )

44. 2. Fermentation of sugar into alcohol by Yeast.
Glucose YEAST Alcohol + Carbon dioxide + Energy
The Alcohol can be separated from the water by distillation.
Alcohol burns so it can be used as a fuel

45. Brazil has lots of sunshine and land for growing crops
Brazil has lots of sunshine and land for growing crops. It can therefore grow lots of sugar cane.
It does not have rich supplies of fossil fuels (COAL,GAS AND OIL ).
These are expensive to import.
Instead, sugar cane is fermented into alcohol which is then mixed with petrol to make GASOHOL .
This is used instead of petrol in many vehicles.

46. Harmless to the environment Harmful to the environment
There are advantages in using fermentation fuels rather than fossil fuels;
FERMENTATION FUELS
FOSSIL FUELS
Harmless to the environment
Harmful to the environment
Easy to obtain
Difficult to obtain
Cheap to obtain
Expensive to obtain
Renewable
Non-renewable

47. Protein from Microbes
Most micro-organisms reproduce themselves much faster than the cells of plants and animals.
Given food, water and heat, one bacterium can reproduce asexually to produce many thousands of bacteria within a few hours.

48. The table and graph show bacterial growth under ideal conditions

49. Most of a bacterial cell is composed of protein.
Industry is able to use fast growing bacteria to manufacture protein-rich foods.
The bacteria are grown, harvested and dried to form a protein-rich powder called single-celled protein which is used as animal feed.
Some fungi produce a protein called mycoprotein, which can be processed to produce meat substitutes for cooking.