Potential replacement of septic tank drain fields by artificial marsh waste-water treatment systems

A waste-water treatment system, which can be used only during the growing season and therefore could be employed in camping areas and similar locations, uses emergent marsh vegetation planted in a gravel substratum in a plastics-lined trench. A pilot plant treating unchlorinated primary sewage effluent achieved the following reductions: BOD 77 per cent, COD 71 per cent, orthophosphate 35 per cent, total phosphorus 37 per cent, nitrate 22 per cent and coliform bacteria 99.9 per cent. This treatment could in certain cases replace individual septic tanks which have been cited as a source of ground-water pollution.