Reed beds for biosolids drying in the arid northwestern United States

Abstract

Reed beds for dewatering biosolids have been successful throughout Europe and in the northeastern temperate United States. This paper reports on the use of reed beds in the arid Columbia Basin in the state of Washington, USA. Native stands of the common reed, Phragmites australis were propagated and planted in the reed beds. The hot, dry, windy, climate has required simple changes in standard operation of the reed beds. The reeds were stressed by the hot dry winds and lost top shoot growth when beds remained drained in the Spring Summer and Fall months. Maintenance of water levels in the cells has reduced symptoms of heat stress in the plants. These operational changes may have an effect on oxidation of organic matter and nitrogen in the filtrate. The operational changes may have effected the dewatering and decomposition of the biosolids. The dry hot summers, and freezing winters enhance the dewatering ability of the reed beds and make them an appropriate solids dewatering technology for the region.