Contemporary sustainability issues in urban areas

Waste Management

Waste management and recycling in cities

• To ensure sustainability cities must manage waste efficiently

• The aim of waste management is to extract the maximum practical benefits from products and to generate the minimum amount of waste

• The waste hierarchy is the cornerstone of most waste minimisation strategies

Waste management hierarchy

The concept lays out the order in which options for waste management should be considered preferable in terms of their environmental impact.

Political aspects of waste management • EU and UK governments produce targets for

local authorities to reduce waste in landfill • Local authorities must increase the amount of

waste recycled • Fines are given if targets are not met – Some local authorities have considered fining

households for throwing away waste more than average and rewarding those who throw away less than average

– However the press produced a large campaign against this and it has diminished

Management strategies • Strategies vary between regions because of

different waste types, amounts, area available and land uses

• In London alone there are differences in the amount of waste recycled

WASTE MANAGEMENT METHODS

Disposal

• Disposing in landfill involves burying waste • Most established in disused quarries or mines– If well managed landfill is inexpensive and relatively

hygienic– If badly managed landfill can create adverse

environmental impacts • Vermin, wind blown litter and leaching • By- products e.g. methane gas and carbon dioxide

• Modern landfill sites include methods to minimise the negative effects of the waste

Incineration

• Combustion of waste material – Convert waste into heat, gas and ash • Burn waste in a furnace

• Practical method of hazardous waste disposal– Biological medical waste

• Controversial – Gaseous pollutants

Recycling methods

• Process of extracting value or products from waste = recycling – Recover/ reuse material

• The raw materials may be extracted and reprocessed or the energy may be converted to electricity

Physical reprocessing • Developed countries recycling = collection and reuse

of waste materials – Sorted and raw materials are reprocessed into new

products • Recycling materials may be collected at different

times to normal waste using dedicated collection vehicles

• Products that are recycled include: – Aluminium cans, steel tins, plastic bottles, glass bottles etc.

• Composed of one material = easily recycled • Recycling of more complex products is more time consuming

and difficult

Biological reprocessing

• Organic waste e.g. plant material can be composted – Resultant material can then be recycled as mulch

• Waste gas from the process captured– Generate electricity

• Variety of composting methods – Compost heaps to industrial scale enclosed vessel

digestion of domestic waste

Energy recovery

• Energy content of waste harnessed directly – Direct combustion fuels – Indirect processing into another fuel

WASTE REDUCTION METHODS

Reduction

• Reuse second hand products• Repair broken items • Designing refillable items and items which use

less material

DEFRA

• Set targets for local authorities – Encourage them to reduce landfill and increase

recycling rates