Energy and Environment 9

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What biodegradation processes similar to landfill?
Similar biodegradation processes in landfill occur in cows, marshes, rice fields, and anaerobic sludge digestion. All produce CH4.
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What is hydrolysis phase 1 of landfill decomposition? (Uses aerobic bacteria)
Phase 1: Aerobic conditions due to trapped air, aerobic bacteria metabolise waste to produce CO2, H2O and heat, temp reaches 70-90 degrees. Availability of oxygen limiting factor. Reactions as in composting (Aerobic)
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What is phase 2, fermentation? (anaerobic)
phase 2: hydrolysis/fermentation. Anaerobic conditions. Carbohydrates and proteins break down to give sugars, CO2, NH3, H2 and volatile fatty acids organic acids (mainly acetic). Temp falls to 30-50 degrees and 80% landfill gas CO2, 20% H2.
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What's phase 3 in landfill decomposition?
Acetogenesis: Organic acids from phase 2 converted to acetic acid, CO2, and H2. pH 4 conditions promote metal solubility and leaching. Methanogenic bacteria slowly dominate.
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What's methanogenesis phase of landfill decomposition? (stage 4)
Methanogenesis: - main landfill gas generate phase, 60% methane 40% CO2, slow reactions, temps 30-35 degrees, acids degraded so pH rises to 7-8. Landfill gas generated between 15-30 years
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Whats stage 5, oxidation?
End of all degradation reactions, residual solids in equilibrium with environment
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What liquids make up leachate?
Liquid in landfill consists of liquids which enter site and material that is leached from wastes as liquid percolates/
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How is leachate taken from landfills?
Low permeability clay prevents leachate escaping, collection and drainage system takes leachate to leachate collection sumP
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What are landfill gas components? What causes odour?
Methane makes 64.8% volume, CO2 33.6%, odours are caused by trace S containing compounds from amino acids and gypsum wastes
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What is chemical oxygen demand?
Chemical oxygen demand (COD) test uses strong chemical oxidising agent to measure amount of oxidisable organic matter. Dermines amount of oxygen needed to chemically oxidise organics in wastewater.
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What is TOC and what do high levels indicate?
Total organic carbon (TOC) measure of total mass of organic carbon per liter of sample. High COD, BOD, and TOC indicate highly polluting water
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What are prevalent in leachate?
There are high levels of chloride and ammonium in leachate in phases 2-3 and phase 4
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How do BOD, COD, and TOC change with degradation in leachate from acetogenic to methanogenic?
BOD, COD, and TOC decrease by phase 4 (From BOD5 of 20,000 to 40,000 to BOD5 of 50-500)
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Other cards in this set

Card 2

Front

What is hydrolysis phase 1 of landfill decomposition? (Uses aerobic bacteria)

Back

Phase 1: Aerobic conditions due to trapped air, aerobic bacteria metabolise waste to produce CO2, H2O and heat, temp reaches 70-90 degrees. Availability of oxygen limiting factor. Reactions as in composting (Aerobic)

Card 3

Front

What is phase 2, fermentation? (anaerobic)

Back

Preview of the front of card 3

Card 4

Front

What's phase 3 in landfill decomposition?

Back

Preview of the front of card 4

Card 5

Front

What's methanogenesis phase of landfill decomposition? (stage 4)

Back

Preview of the front of card 5
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