Possibility of Cattail for Waste-water Treatment   Supaporn Junrungreang and Pitsabu Jutvapornvanit   ABSTRACT         Cattail ( Typha sp. ) is a perennial aquatic weed which grows and spreads very fast in ponds, canals and reservoirs throughout tropical and temperate zones. It can tolerate in some degree of salinity, acidity and alkaline environment. The important properties of cattail are high natural productivity and has ability to absorp large amount of nutrients and heavy metals. So the possibility of cattail utillization to waste-water treatment was investigated at Land Development Department in 1996. Cattail can produce large quantities of biomass, the total annual productivity approximately 56.6 ton/ha. The biomass above ground and below ground are in the range 3.8-52.7 and 9.7-101.4 ton/ha respectively. Cattail is effective in nutrient removal. The removal nutrient capacity of nitrogen and phosphorus are 760 and 60 kg/ha. respectively. The comparison studies of the elements content in organs of broad-leaf cattail ( Typha latifolia ) and narrow-leaved cattail ( Typha angustifolia ) indicated that above ground and below ground of Typha species are different. Element content; N, P, K, Ca, Mg, Na, Mn, Zn and Cu in every organs of broad-leaf cattail are larger than narrow-leaved cattail and the highest nutrients of above ground organs are N, K, Ca, Mg and Mn. The maximum nutrient content of below ground organs are Na, Zn and Cu. The largest N content in both Typha sp. are in the range 2.5-2.9% but the lowest P concentration is found in leaf-blade and leaf-sheath. Typha sp. is rather hight capacity to adsorp the heavy metals such as Mn, Zn, and Cu. The elements accumulated in broad-leaf cattail more larger than narrow-leaved cattail. Seasonal dynamic also has affected to chemical elements and biomass in cattail. The maximum leaf-area of broad-leaf cattail and narrow-leaved cattail are in August which resulted the largest N, P, K content and also biomass of above ground organs in summer. The peak of nutrient content of N, P and K below ground organ is in final fall. The biomass above ground of broad-leaf cattail is larger than narrow -leaved cattail but biomass below ground of broad-leaf cattail is smaller than narrow-leaved cattail. The largest biomass below ground is in the begin ning of winter. Cattail can be used as water purification and it should be harvested during summer for waste-water treatment.         Key words : Typha spp, Typha latifolia, Typha angustifolia