Quick Answer
Grey water can be filtered for irrigation using a combination of physical, biological, and chemical methods. Pre-treatment typically involves sedimentation and coarse filtration, followed by finer filtration such as cartridge or sand filtration. Biological treatment using wetlands or bio-reactors is also effective.
Pre-Treatment Methods
Pre-treatment is crucial in grey water filtration for irrigation. Sedimentation tanks can be used to remove large particles and debris, allowing the water to flow into a coarse filter such as a screen or a mesh filter. The recommended size of the sedimentation tank is 1-2 days of peak water use, and the screen or mesh filter should have a pore size of 1-2 mm to capture particles larger than 1 mm in diameter.
Biological Treatment Methods
Biological treatment methods such as wetlands or bio-reactors are effective in removing pathogens and contaminants from grey water. Wetlands are natural or artificial systems that use plants, microorganisms, and other organisms to break down organic matter. Bio-reactors, on the other hand, use microorganisms to break down contaminants. The ideal water flow rate for a wetland or bio-reactor is 0.1-1.0 m3/hour, and the recommended depth is 0.5-1.5 meters.
Final Filtration and Disinfection
After biological treatment, the grey water should be filtered again using a finer filter such as a cartridge or sand filter to remove any remaining particles and contaminants. Disinfection methods such as UV treatment or chlorination can also be used to kill any remaining pathogens. The recommended flow rate for final filtration is 0.01-0.1 m3/hour, and the recommended pressure drop is 1-5 psi.
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