Nutrient Removal in a Reed Bed System

Since 1984 investigations concerning sewage technology, plant physiology and soil properties have been carried out on the reed bed system at Mannersdorf/Leithagebirge (local loamy soil, Phragmites, planted area 3×150 m², influent 30 - 50 mm/d). The removal efficiency of COD and BOD₅ amounts to 80-90 % and 90 - 98 %, respectively. Elimination of nutrients (N_TOT and P_TOT) varies from 3 0 to 60 %, in general. Total nitrification cannot be reported for any of the plots fed with different sewage qualities. Nutrient uptake of N_TOT and P_TOT by Phragmites a. reaches 30 or 15 % of influent sewage load during July and August but is of no importance with respect to the average of the year. The proportion of P_TOT in the soil is still increasing every year and now amounts to about 450 mg/100g soil. The concentration of phosphorus essentially stagnates at the level of 50 mg/100g soil.