Greywater treatment & recycling – some info

Greywater recycling not only saves water but it reduces water bills too. Just remember never to store untreated greywater in a water tank or drum for more than 24 hours as potentially harmful bacteria could begin to multiply (a low levels they may be virtually harmless but can become dangerous at higher levels).

A large proportion of household water becomes greywater

What is Greywater?

Greywater can be defined as any domestic wastewater produced, excluding sewage. The main difference between greywater and sewage (or blackwater) is the organic loading. Sewage has a much larger organic loading compared to greywater.

Some people also categorise kitchen wastewater as blackwater because it has quite a high organic loading relative to other sources of wastewater such as bath water.

People are now waking up to the benefits of greywater re-use, and the term “Wastewater” is in many respects a misnomer. Maybe a more appropriate term for this water would be “Used Water”.

What Can Greywater Be Used For?

With proper treatment greywater can be put to good use. These uses include water for laundry and toilet flushing, and also irrigation of plants. Treated greywater can be used to irrigate both food and non food producing plants. The nutrients in the greywater (such as phosphorus and nitrogen) provide an excellent food source for these plants.

What Are The Benefits of Greywater Re-use?

Re-using water does not diminish our quality of life, however it can provide benefits on many levels.

Two major benefits of greywater use are:

• Reducing the need for fresh water. Saving on fresh water use can significantly reduce household water bills, but also has a broader community benefit in reducing demands on public water supply.
• Reducing the amount of wastewater entering sewers or on-site treatment systems. Again, this can benefit the individual household, but also the broader community.

How Is The Greywater Treated For Re-use?

There are many ways by which to treat greywater so that it can be re-used. The various methods used must be safe from a health point of view and not harmful to the environment.

There are types of greywater systems that rely on plants and natural microorganisms to treat the water to a very high standard so that it can be safely re-used. The main advantage with these types of systems is that they treat the greywater naturally, and also enhance the local environment because of the attractive plants used and the fauna attracted to them.

There are other natural systems available to treat greywater. The type of system selected will depend on the specific application, and selection would be considered on a case by case basis.

What About Treatment of Sewage?

When direct composting of sewage is neither possible or preferred, there are other options to allow for the natural and safe treatment of this wastewater, whilst at the same time getting the benefit of the water and nutrients in the wastewater.

Source: Sustainable Earth Technologies

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