presentation by Ian Lawrence
Greywater recycling
Greywater offers an economic and reliable source of water for garden watering and other uses.
The treatment requirement reflects:
- the proposed water use and
- the means of delivery.
The size of the required storage is determined by:
- the volume of greywater produced per washing cycle and
- the time required to hold the greywater before watering.
Use of greywater
Uses (in order of treatment req’ms):
| Use |
Treatment requirement |
| Dripper water Supply |
Filtration of solids. Use of detergents low in Phosphorus & sodium, pH neutral |
| Spray irrigation |
Filtration + measures to limit aerosol drift & surface residues on fruit & vegetables, or disinfection |
| Toilet flushing |
Advanced filtration + biological treatment to remove colour & odour |
| Storage |
Aeration to limit odour problems |
Sources of greywater
- Bathroom basin and shower wastewater
- Laundry wastewater (subject to selection of suitable washing detergent)
Note kitchen wastewater is generally not suitable for recycling, due to potential for high levelsof fat & oil
Accessibility of wastewater
- Use of Washing Machine pump to deliver waste water to greywater treatment/storage tank.
- Use of gravity or special pump to deliver bathroom wastewater to greywater system
Treatment of greywater
- Treat to a quality appropriate to use.
- Lint screening – fine wire screen
- Filtration to remove fine particulates – sand filter
- Advanced filtration – to remove odours & colour
- Biological treatment to remove nutrients.
Storage of greywater
- Aeration – turnover stored greywater to limit odour development
Health issues
- Slight risk of ingestion of faecal contaminants for general laundry and bathroom sources.
Minimised by:
- excluding human contact (dripper system)
- washing of sprayed fruit or vegetables,
- disinfection treatment where potential for aerosol drift with spray irrigation.
