8.3 - Solid domestic waste

Solid Domestic Waste (SDW)

Our trash and garbage from residential and urban areas. It is a mixture of paper, packaging, organic materials, glass, dust, metals, electronic waste, and more. It is collected from homes and shops and more.

Type of SDW - Biodegradable

Food waste, paper, green waste

Type of SDW - Recyclable

Paper, glass, metals, some plastics, clothes, batteries

Type of SDW - Electronic Waste

TVs, computers, phones, fridges

Type of SDW - Hazardous

Paints, chemicals, light bulbs

Type of SDW - Toxic

Pesticides, Herbicides

Type of SDW - Medical

Needles, syringes, drugs

Type of SDW - Inert

Concrete, construction waste

Type of SDW - Mixed

Tetrapaks, plastic toys

What are the aims of the circular economy

• To be restorative of the environment

• Use renewable enegy sources

• Eliminate or reduce toxic wastes

• Eradicate waste through careful design

How does the circular economy work?

It relies on manufactureres and producers retaining ownership of their products and being responsible for recycling them or disposing them when the consumer has finished using them.

The producers act as service providers, selling use of their products, not the products themselves. This means that they take back products when they are no longer needed, disassemble or refurbish them and return them to the market

What are the three strategies to minimize waste?

Reduce

• Use less resources, change shopping habits

  • buy things that last, look for items with less packaging, choose products that are energy efficient

Reuse

• Products are used for something other than their original purpose or they are returned back to the manufacturer and used repeatedly

  • Returnable bottles - give back to manufacturer

  • Compost food waste

  • Use old clothes as cleaning rags

  • Read E-books

Recycle

• Involves collecting and separating waste materials and processing them for reuse.

  • Ex. in Germany, each household has 4 bins for this

Strategies for waste disposal

Includes: Landfills, Incineration, Composting

How do Landfills work?

Waste is taken to a suitable site and buried there, hazardous waste can be buried as well. The cost is relatively cheap

They are carefully selected to not be too lose to areas of high population density, water courses and aquifiers. They are lined with a special plastic liner to prevent leachate seeping out

Methane produced as a resulting of fermenting organic material in the waste is either collected and used to generate electricity or vented into the atmosphere. Soil is pushed over the waste each day to reduce smells and pests

It is difficult to find new sites

Advantages of Landfill sites

• Cheap method of waste disposal with low setup and running costs

• Gases such as methand can be collected for waste-to-energy schemes

• Creates jobs for the local community

• Old landfill sites can be landscaped and re-used for building projects

Disadvantages of Landfill sites

• These sites give off dangerous gases that cause air pollution and global warming (methane)

  • There is also potential for explosions if methane builds up

• Liners can fail and leachates leak into the local environment and groundwater sources

• Settling after compaction can cause problems for future uses - must be left a long time to settle fully

• Waste collection vehicles have to travel a long way to alternative sites

• Landfills are filling up = lifespan of landiflls is limited

• Poorly managed sites can result in rats, mice, flies increasing the spread of diseases

• Heavy vehicles cause traffic problems and damage local roads

• Poorly managed sites can cause problems with dust, odor, visual, and noise pollution - can negatively impact local property prices in the area

• Contribution to marine debris - poorly managed sites have litter that gets blown by the wind to seas and oceans

How do incinerators work?

They burn waste at high temperatures up to 2,000° C. In some, the waste is pre-sorted to removie incombustible or recyclable materials. Then the heat produced is often used to generate steam to drive a turbine or heat buildings directly (waste-to-energy incineration).

In others, waste is burned but this can cause air pollution from burning plastics, heavy metals, burning batteries, and nitrogen oxides. The ash from ______ can be used in road building and the space taken up is less than landfills

However, they are expensive to build and need a constrant stream of waste, encouraging people to produce waste

Advantages of Incineration

• Reduces the volume of waste by 80-85% therefore it is very popular in countries where land is scarce (ex. Japan)

• Very useful for clinical waste or hazardous wate contaiing pathogens

• Used to generate local district heating in Denmark and Sweden

• Can be used to generate electricity

• Incineration plants retrieve metal from the ashes and this can then be recycled

Disadvantages of Incineration

• Emits varying levels of toxic heavy metals (manganese, chromium, nickel, arsenic, mercury, lead)

• New incinerators are taking away the funding from other renewable energy research and development

• Old incinerators emit dioxin and furan, carcinogenic gases

• Causes property devaluation in surrounding areas

• Causes visual pollution due to intrusive chimney stack

• Filters do not remove the finest particles from air emissions

• Many people in LEDC’s live on sifting waste, incinerators take away this livelihood

• Set up costs are high (expensive)

Anaerobic digestion

When biodegradable matter is broken down by microorganisms in the absence of oxygen.

The methan produced can be used as fuel and the waste later used as a fertilizer or soil conditioner

Domestic organic waste

This can be composted or put into anaerobic digesters. Composting can be done at home on a small scale or local government authorities can collect home organic waste and compost on a larger scale