Abstract

Three VF-beds operating in hybrid constructed wetlands in configuration HF-VF-HF were analysed. These hybrid constructed wetlands provide the II stage biological treatment. They are located in Pommerania voivodship, in Sarbsk, Wiklino and Wieszyno, and their capacities are 29.5, 14.2 and 21.6 m3/d, respectively. The article focuses on performance and operation of VF-CW plants during one year. Based on removal of organic matter and nitrogen, calculations of oxygen requirements and ability of oxygen supply were carried out.For the purpose of oxygen requirement calculations, the discharged load of organic substances and the properties of the bed material had to be identified.The following parameters were identified to be crucial for respiration dynamics of vertical flow wetland systems: gas porosity of the filling material (ng), unit oxygen consumption (a) determining the dose of organic substances, volumetric soil water content (Qp).The facility in Wiklino had the highest average removal efficiencies of organic matter and ammonia nitrogen (85.4% COD and 70.7% N-NH4+) at the loading of 13.4 gCODm-2d-1. The lowest removal efficiencies were observed in Wieszyno (24.7% COD and 1.2% N-NH4+) at the loading of 43.6 g CODm-2d-1. It was proved that in VF-CW beds in Wieszyno and Sarbsk favourable conditions for colmatation occur.

Authors (3)