Lecture 9: Circular Economy (Material Recycling)

Question 1

What are some statistics on how big the waste problem is in the UK?

Answer 1

• UK produces enough waste to fill Trafalgar Square every day
• UK families throw away 6 trees worth of paper a year
• Per 1 tonne consumed, 10 tonnes of resource input
• UK consumes 8 billion cans and plastic bottles per year

Question 2

What authorities manage waste control in the UK?

Answer 2

• Waste regulatory authorities (responsible for licensing sites, carriage and waste disposal procedures)
• Waste disposal authorities (arranges disposal of waste and provides refuse amenity sites)
• Waste collection authorities (collects household waste and makes arrangements to collect commercial and industrial waste if requested)

Question 3

Who regulates uncontrolled waste in the UK?

Answer 3

Environmental Agency - ensures uncontrolled waste doesn’t pollute the environment or public

Includes:

• Agriculture, mining and quarry waste (not currently inspected)
• Industrial special/hazardous waste (explosive etc.)
• Inert waste (uncontaminated earth, excavation waste eg. Sand, bricks)

Question 4

What is Municipal Solid Waste?

Answer 4

MSW covers household and commercial waste. Collected and disposed by local authorities - 90% is household.

Question 5

What is clinical waste regulated by and what is it?

Answer 5

• Controlled Waste Regulations 1992
• Arises from the treatment of humans and animals in healthcare environments (which are capable of causing infection or other harm)
• England and Wales produce about 350,000 tonnes per year
• Producers must ensure Duty of Care (pass their waste to a waste carrier registered by EA
• Usually clinical waste is destroyed by high temp incinerators

Question 6

What is hazardous and special waste regulated by?

Answer 6

• Control of Pollution (Special Wastes) Regulations 1980
• Consignment note system tracks every point from source to disposal, copy must be passed to EA

Question 7

What effect has the EU landfill directive had on the waste industry in the UK?

Answer 7

• Waste sites are classified into hazardous, non-hazardous and inert
• Biodegradable waste is being diverted away from landfills
• Pre-treatment is required before waste enters landfill

Question 8

What are waste holder’s legal responsibilities?

Answer 8

1) Prevent other people from committing a criminal offence of unlicensed waste disposal

2) Stop waste escaping from their control

3) Ensure waste is transferred only to an authorised person

4) Provide written description to prevent other people from committing the offence of illegal disposal or any escape of waste being transferred

Question 9

What is the Waste Transfer System?

Answer 9

• Transfer of waste must have transfer notes in UK, waste carriers are register by WRA and waste brokers make arrangements on behalf of others to dispose waste.
• Shipment of waste across countries is governed by Transfrontier Shipment of Waste regulations (TFS) - no waste can be imported or exported to UK

Question 10

What are the stages in the waste management hierarchy?

Answer 10

• Reduce
• Reuse
• Recycle
• Disposal

Question 11

What is the material fragmentation process for recycling?

Answer 11

• Shredder
• Granulator
• Pulveriser (Grinder)

Question 12

What is the post fragmentation separation process?

Answer 12

• Magnetic separation (ferrous)
• Eddy current separation (non-ferrous)
• Air Cyclone separation (fines and light particles separate from larger granules by air and gravity)
• Air Zigzag separation (light fraction separate from heavy fraction eg. Plastic, foam)
• Optical separation (plastics etc that have different optical properties, X-rays and NIS used to detect)
• Density based separation (sideways like an Archimedes screw - lighter materials float, heavier ones sink in liquid like ethanol or magnetite)

Question 13

What is recycling by composting?

Answer 13

• Biodegradable wastes can be composted to speed up the natural decomposition process.
• Can take place at a household, community or centralised facility.

Adv - Increases soil nutrient and reduced need for fertilisers.

Dis - Can be a risk to handlers, source of methane and heat

Question 14

How can energy be recovered with anaerobic digestion?

Answer 14

• Series of biological processes whereby microorganisms break down biodegradable material in the absence of oxygen, producing biogas (methane) which is combusted to produce electricity and heat or natural gas.
• Digestate is stable, nutrient rich and can be used for fertilisers or feedstock for ethanol production