form part of small-scale sewage treatment systems. Water trickling through the reedbed is cleaned by microorganisms living on the root system and in the litter. These organisms utilize the sewage for growth nutrients, resulting in a clean effluent. The process is very similar to aerobic conventional sewage treatment, as the same organisms are used, except that conventional treatment systems require artificial aeration. Treatment ponds Treatment ponds are small versions of constructed wetlands which uses reedbeds or other marshland plants to form an even smaller water treatment system. Similar to constructed wetlands, water trickling through the reedbed is cleaned by microorganisms living on the root system and in the litter. Treatment ponds are used for the water treatment of a single house or a small neighbourhood. Gallery See also Organisms used in water purification South Milton Ley References Ecology