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Waste and Decay

Decay processes

  • Decomposers are a group of microorganisms including bacteria and fungi.
  • They feed on waste droppings and dead organisms.
  • Detritus feeders like maggots and worms start with decay processes. They eat dead animals and produce waste material.
  • The waste products of decomposers are carbon dioxide, water and nutrients for plants.
  • Decay means broken down and digested by microorganisms.
  • The recycling of materials through the process of decay makes sure that the soil contains the mineral ions that plants need to grow.
  • Decomposers clean the environment because they remove the bodies of dead organisms.

The Problem of Waste

Conditions for decay

Methods of composting

  • The speed at which things decay depend partly on the temperature. Microorganisms work faster in warm conditions.
  • They slow down and stop if it gets too cold.
  • Decay stops if it gets too hot as the enzymes in the decomposers change shape and stop working.
  • Microorganisms grow better in moist conditions. Moisture helps to dissolve their food and stop them from drying out.
  • Although some microbes survive without oxygen, most decomposers respire like any other organism.
  • This means they need oxygen to release energy, grow and reproduce, which explains why decay takes lace faster when there is more oxygen.
  • Compost heap- Simple and cheap, kitchen and garden waste is put in a pile with new material added. It is left to rot down.
  • Compost bin- Often made of plastic and sold cheaply by local councils to encourage recycling of organic waste. The bin has to be watered in dry conditions.
  • Council composting- Local councils may collect garden or kitchen waste and use large scale bins to make compost. You can buy this compost to put on your garden.
  • Black bag composting- A black plastic bag is filled with kitchen and garden waste and sealed. The microorganisms work slowly as they don't have a lot of oxygen. It takes about a year to make compost.
  • People produce a lot of waste and it is very hard to get rid of.
  • We put about 100 million tonnes of waste each year into landfill sites
  • Any kitchen and garden waste we put into landfill sites don't rot easily
  • This type of waste turns into a liquid and is soaked up by the ground. Then, the liquid can pollute local rivers and streams.
  • In conditions like this, the microorganisms that break down the animal and plant waste produce methane.
  • Methane is a greenhouse gas and it adds to the effect of global warming.

Making Compost

  • Composting can be done and a large or small scale and there are different factors which are important in making compost.
  • Compost can be made with or without oxygen- mixing compost can help air get in and if the microorganisms have oxygen they will make energy which speeds up the energy. Without oxygen there is less energy and it is slower.
  • The warmer the compost is the faster the compost will be made. This stops at about 70 degrees because the microorganisms stop working.
  • The decay process is faster in moist conditions. The decaying process does not take place at all in dry conditions.
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