Biotechnology sub - topic B problems with profit and waste Part 1 SEWAGE
The effect of untreated sewage on rivers Rivers contain bacteria. These bacteria useoxygen during aerobic respiration. Untreated raw sewage contains organic material ( faeces ,food fragments, soap etc) Bacteriafeed on this organic waste, breaking it down to release energy. Theyuse 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
The breakdown of sewage by bacteria releasesNitrates 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 lightgetting to lower aquatic plants, which then die -- the oxygenthey provide during photosynthesis is no longer available Organic waste on river bed broken down by bacteria to release foul smelling gases and rotting materials.
Algal bloom 4 Raw sewage Fish die due to lack of oxygen 1 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
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.
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.
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.
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 aerobicbacteria 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.
Oxygen can be provided in two ways; • Biological filtration The sewage is trickled through filter beds and is broken down by bacteriacoating 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 bacteriaadded to it).Oxygen is then supplied by bubbling compressed air through the mixture. Primary settlement sludge
The treated sewage is then passed to finalsettlement 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.
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.
Sewage Treatment -- Summary 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
Airborne 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.
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.
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).
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
Working close to the hot bunsen flame the loop is heated till red hot then allowed to cool. • This kills organisms on the loop
A sample of bacteria is collected from the culture bottle. The culture bottle is carefully opened and closed next to the flame.
Working close tothe flame the loop is now gently rubbed over the surface of the agarjelly in the dish.
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
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 conditionse.g. extreme drought, heat, pH etc. The thick coat they produce only disintegrates when conditions become favourable again.
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.
CREDIT Decay Bacteriaandfungican breakdown organic matter This process is calledDecomposition. Decomposition is anatural process. The bacteria or fungusobtain energy from breaking down the organic material
Recycling CREDIT Decomposers breakdown dead bodies and waste materials to organic compounds. The organic compounds containMineral salts that are released into the soil. Plants use theseMineral saltsto grow Apart fromMineral saltsthe elementsCarbonandNitrogenalso have to berecycled
Nitrogen Cycle Denitrifying bacteria Atmosphericnitrogen 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)
CREDIT Root nodules Plants like clover, peas andbeans have root nodules containing nitrogen fixingbacteria 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
Carbon Cycle CREDIT There are three main processes; Photosynthesis - usescarbon dioxide Respiration–releasescarbon dioxide Combustion – releasescarbon dioxide
CREDIT Carbon Cycle Atmospheric carbon dioxide respiration respiration respirationby 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
Food and Fuel from Waste Many manufacturing processes produce waste products. These waste products can be upgraded -- fed tomicrobes 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.
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
1. Fermentation of Manure by bacteria To produce methane gas When microbes feed on fresh manure, they produce methane gas ( BIOGAS )
Glucose YEAST Alcohol + Carbon dioxide + Energy 2. Fermentation of sugar into alcohol by Yeast. The Alcohol can be separated from the water by distillation. Alcohol burns so it can be used as a fuel
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.
There are advantages in using fermentation fuels rather than fossil fuels;
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.
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.