Energy from waste

Question 1

Give examples of combustible waste and recyclable waste

Answer 1

combustible - garden waste, paper, kitchen waste, wood, dense plastic, plastic film, textiles
recyclable - paper, glass, metal

Question 2

What are the key features of an engineered landfill site

Answer 2

natural rock foundation, leachate collection system, gas extraction pipe, impermeable clay cap, synthetic membrane liner

Question 3

What are the 5 stages of landfill decompostion

Answer 3

aerobic hydrolysis, fermentation, acetogenesis, methanogenesis, oxidation

Question 4

What are the properties and conditions of methanogenesis

Answer 4

mesophilic, 30-35c, slow, produced methane and co2, pH increases as acids are degraded

Question 5

What occurs in acetogenesis

Answer 5

organic matter becomes carboxylic acids mainly ethanoic acid, CO2 and water.

Question 6

What is leachate

Answer 6

liquid formed in the landfill composed of liquids that enter the landfill such as rain as well as leached material as the liquid percolates down

Question 7

What happens to the landfill gas that is collected

Answer 7

they go to gas treatment plants to remove moisture and sulfur then they are combusted

Question 8

What is free energy

Answer 8

Energy that is free to perform useful chemical work such as bond breakage or formation

Question 9

What are the 3 things required for an effective combustion

Answer 9

time, temperature, turbulence (oxygen and contact)

Question 10

What are the advantages of energy from waste

Answer 10

no methane production, energy produced, emissions are controlled, incineration is close to waste is generated/collected so fewer carbon miles, incinerator ash can be used as aggregate, no long term liabilities

Question 11

What are the disadvantages of energy from waste

Answer 11

generates CO2, public doesn’t have a good perception of it , can be costly, can produce toxic emissions