4.1. Organic Waste – Types, Sources, and Uses

There are types of organic waste that are commonly discarded. Below, we will look at types and sources of organic waste, along with examples of their common uses.

Domestic or Household Waste

This waste is usually made up of food scraps, either cooked or uncooked, and garden waste, such as grass cuttings or trimmings from bushes and hedges. Domestic kitchen waste is often mixed with non-organic materials, such as plastic packaging, that cannot be composted. It is beneficial if this waste can be separated at source because its recycling will be far easier. Domestic or household waste is usually produced in relatively small quantities. Developing countries generate a much higher organic content in domestic waste.

The principal recycling of domestic wastes is depicted in the schematic diagram below.

LO10 3

Domestic waste recycling process

Commercially Produced Organic Waste

This is waste generated by institutional buildings, such as schools, hotels, and restaurants. The quantities of waste generated there are much higher and the potential for its use in small-scale enterprises is good.

Animal and Human Waste

It is worth mentioning that there are serious health risks in handling sewage. Raw sewage contains bacteria and pathogens that cause serious illness and disease. One should stress that health and safety procedures should be followed in dealing with sewage. People dealing with its handling should have a clear understanding of the health risks involved. Raw sewage should never be applied to crops for consumption by humans or animals.

  • Human faecal residue is generated in large quantities in urban areas and is dealt with in various ways. In the worst cases, little is done to remove or treat the waste, so it can present enormous health risks. This is often the case in the slum districts or poor areas of large cities. Sewage is often dealt with crudely and is pumped into the nearest water body with little or no treatment. There are methods for large-scale treatment and use of sewage as a fertiliser and source of energy. The most commonly used method is anaerobic digestion to produce biogas and liquid fertiliser. Composting toilets facilitate the conversion of human faecal waste into rich compost.
  • Animal residue is rarely wasted. This fertile residue is commonly used as fertiliser, being applied directly to the land, or as source of energy, either through direct combustion (after drying), or through digestion to produce methane gas.
  • Agricultural Residue. This waste remains after the processing of crops, e.g., maize stalks, rice husks, foliage, among others. There are a wide variety of applications for it, ranging from simple combustion on open fire to complex energy production processes that use it for fuel source.

 

  • LO10 4Outer equipment of a solid-waste treatment plant that generates electricity
  • backnext

Intranet