Treatment of domestic and agricultural wastewater by reed bed systems

The purification capacity and seasonal variability of two newly created reed bed systems was monitored over 1 year. In one of the systems treating domestic wastewater, the reduction in the concentrations of chemical oxygen demand (COD), total N, total P and fecal coliform bacteria (FC) ranged from 80 to 9%. In the second system, treating a mixture of domestic and agricultural wastewater produced by a cheese dairy, treatment efficiency ranged between 13 and 99%. The removal rates did not show any seasonal pattern for domestic wastewater, in contrast to the mixture of domestic and agricultural wastewater with increased removal rates in the summer. Bacteria which are involved in N metabolism was estimated by the most probable number-test (MPN). In both reed bed systems the MPN of proteolytic bacteria, ammonifiers, nitrifiers and denitrifiers/g DW of gravel substrate were of the orders of magnitude of 10(4)-10(6), 10(5)-10(7), 10(1)-10(5) and 0-10(3), respectively. On the basis of the microbial assemblage there is a need to improve the conditions for both nitrification and denitrification to enhance the efficiency of N removal. (C) 1999 Elsevier Science B.V. All rights reserved.