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Flashcards in 2016 - Past Paper Questions Deck (18)
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1
Q
Explain the following terms:
Low Solids
High Solids
Residence Time
Single - Stage
Multi - Stage
A

Low solids:
Low solid digestion is where the feedstock is around 15% solid material [1]
High solids:
High solid digestion is where the feedstock is around 55% solid material. [1]
Residence Time:
The time taken for the full degradation of the material in an anaerobic digestion system. [1]
Single Stage:
The biological reactions occur in one holding tank and the biogas comes from this tank. [1]
Multistage:
Hydrolysis, acetogenesis and acidogenesis occurs in one tank whilst the methanogenesis which produces the biogas occurs in a separate tank. [1]

2
Q

Outline how anaerobic digestion can be used to provide heat and power (CHP)

A

Biogas from an AD plant can be burnt in a CHP plant to generate power (electricity) and heat [1];
Instead of losing the heat, as in traditional power plants, it is diverted into local heating systems. [1]

3
Q

Name three types of waste product which can be composted in a domestic situation

A
Any three from:  
• Lawn clippings. [1]   
• Shredded stalks. [1]  
• Vegetable peelings. [1]   
• Hedge clippings. [1]  
• Cut flowers. [1]  
• Tea bags. [1]  
• Leaves. [1]  
• Eggshells. [1]
4
Q

Explain briefly why composting is unsuitable for treating any form of catering waste

A

Cooked food must never be used in composting because it will attract vermin

5
Q

Describe one efficiency measure which can be implemented on the window and explain why this measure would improve the energy efficiency

A

Any one measure and explanation from:
• Sealing around the edges of the window [1]; this will improve airtightness and reduce heat loss caused by draughts. [1];
• Installing double (or triple) glazed windows [1]; These will have improved U-values and will reduce heat loss through window. [1];

6
Q

State one economic and one environmental benefit of energy conservation to be gained by putting in cavity insulation

A
Economic benefits: 
Any one from:  
• reduced heating costs.   
• improving the value of your home.  
• grant assistance available for the work.
Environmental benefits: 
Any one from:  
• reduced carbon emissions.   
• increased levels of home comfort.  
• reducing likelihood of condensation and mildew.
7
Q

Explain how a tidal barrage generates energy from the tides

A

A barrage is built across an estuary with gates and turbines built into the wall of the dam [1];
As the tide flows in the gates are open and the turbines are operated producing electricity [1];
At high tide the gates are closed trapping the water inside [1];
When water level outside has fallen sufficiently(e.g. 5 m) the gates are opened [1];
The released water turns the turbines again producing electricity. [1]

8
Q

Outline two advantages of a Tidal stream generator over a tidal barrage installation

A

Any two advantages from:
• They are cheaper to construct. [1]
• They are smaller and have less environmental impact. [1]
• The turbine blades turn slowly and have less effect on sea life. [1]

9
Q

Give one Example of a ‘Geo - Engineering’ technique and explain how it can be applied

A
  • Cloud seeding [1] where clouds are injected with crystals to produce ‘rain on demand’. [1]
  • Space reflectors [1] which block a proportion of the sun’s rays from entering the earth’s atmosphere thereby reducing global warming. [1]
  • Afforestation [1] whereby global scale planting of trees absorbs CO2 from the atmosphere. [1]
  • Biochar [1], the process of ‘charring’ biomass so that the carbon it contains is locked up in the soil. [1]
10
Q

Describe the operation of Bio-Photovoltaic devices

A

Bio-Photovoltaic (BPV) devices generate electricity from light energy [1] by exploiting the photosynthesis of living organisms such as moss, algae, cyanobacteria and vascular plants. [1]

11
Q

Describe the process of Bioremediation

A

Adding micro-organisms to soil [1] to remove contaminants.

12
Q

Discuss the economic and environmental benefits of using bioremediation techniques compared to traditional treatment methods

A

Bioremediation:
• Bioremediation can be carried out under atmospheric conditions.
• Bioremediation can be carried out in situ so soil is not removed from the site.
• The contaminants are reduced to (almost) zero.
• The by-products are non-toxic so water and air pollution is minimised.
• Bioremediation uses bacteria that occur naturally in the soil so the ecosystem is maintained.
• Bioremediation is economical because it does not require large energy inputs.

Traditional treatment:
• Traditional treatment is expensive because of the high energy costs (heating).
• Greenhouse gases such as carbon dioxide are produced.
• Soil may need to be treated ex situ/off site which requires heavy machinery.
• Traditional treatment can produce toxic by-products which require further treatment.
• Soil may need to be disposed of after treatment which leads to increased landfill.

13
Q

Outline the role of genetic engineering in modifying micro organisms for bioremediation

A

Any two points from below:
Micro-organisms can be genetically engineered to:
• decontaminate a site more rapidly than unmodified micro-organisms;
• tolerate harsher conditions;
• remove toxic materials (such as heavy metals).

14
Q

Identify two issues of concern arising from the use of genetic engineering of micro organisms for bioremediation

A

Any two from:
• Genetically engineered micro-organisms may wipe out existing bacteria.
• They may affect the existing soil ecology with unknown consequences.
• They may not behave the same way in the field as they do under laboratory conditions.

15
Q

Describe two difficulties with locating a new landfill site

A

Any two points from:
• Planning permission is required which can delay the landfill becoming operational by several years. [1]
• A permit is required for operation which requires that full surveys have been carried out. This process is time consuming and adds to the up-front costs for the operator. [1]
• There may be objections from local residents due to noise/odour issues. This will delay planning permission being granted and subsequent award of a permit. [1]
• Suitable transport links are required so that waste can be brought to the site in heavy goods vehicles. [1]

16
Q

Describe two difficulties with developing a new landfill site

A

Development:
Any two points from:
• Once a permit/licence has been granted it takes a further 18 months from beginning of construction to operation adding to up-front investment costs. [1]
• The site must be geologically suitable so that the polluting leachates from the site cannot affect the surrounding land and water. [1]
• A detailed site survey is required prior to operation to ensure that the landfill site will not cause movement of the surrounding land. [1]
• An environmental assessment is required to confirm that the effect of the landfill site on the local environment is minimal. [1]
• The landfill must include leachate and landfill gas treatment measures to minimise water and air pollution. [1]
• Leak detection is required as flammable methane gas can be released. Methane gas is a greenhouse gas. [1]

17
Q

Name one major waste type

A

Any one from:
Municipal waste/Commercial and industrial waste/Construction, demolition and excavation wastes/Hazardous waste/Agricultural waste.

18
Q

Discuss the main characteristics that you would propose for this urban development that would link sustainability, zero carbon concepts and the role of technology. Specific reference to the following:

  • Reduced energy use for heating/cooling and microgeneration (smart grid technology)
  • Integrated and flexible transport facilities/versatile buildings
  • Waste management/Land use
  • Dealing with water shortages/sustainable urban drainage
  • Green Spaces - environmental benefits
A

Energy use for heating/cooling and microgeneration (including the use of smart grid technology):
• reduced energy use for heating and cooling; passive ventilation; natural cooling; better insulation, glazing, orientation.
• microgeneration of electricity (using solar power and micro wind linked via smart grid) and heat using heat pumps, biomass etc.

Integrated and flexible transport facilities/versatile buildings:
• public transport, cycling, walking, park and ride, etc.
• lower cost and more comfortable and versatile buildings/design for re-use etc.

Waste management/land use (brownfield sites):
• planned waste management systems that deal with the waste source (e.g. waste management strategies; recycling; composting; biomass etc.).
• the reuse of brownfield sites (e.g. building on previously developed land)

Dealing with water shortages/sustainable urban drainage.
• systems to deal with water shortage (e.g. managing water usage; water metering; low water usage sanitary ware; rainwater harvesting; greywater recycling; etc.).
• sustainable urban drainage schemes (e.g. flood mitigation measures; SUDS).

Green spaces – environmental benefits:
• using green spaces to moderate the urban heat island (e.g. using trees to create shade/ local microclimate/ heat sinks).
• using green spaces that work for people and wildlife, for example food production in urban areas.