3.2. COD removal in the reactor system
The organic matter removal was inspected by observing COD during the operating time. COD removal percentages could be seen in Fig. 1. COD removal efficiencies were obtained as 82% (n = 8, σ = 6) in AS reactor, 77% (n = 8, σ = 11) and 80% (n = 45, σ = 6) in the system. The removal efficiencies of AS reactor were obtained as the range of efficiencies of general biological treatment. However, note that COD removal efficiencies were decreased by the last time of operation as root of plants can be decomposed and dissolved and so COD of effluent may increased to higher value in the VSFCW.