Utilization of created wetlands to upgrade small municipal wastewater treatment systems

Created wetlands offer a low cost, low maintenance, and practical alternative for upgrading secondary municipal wastewater treatment systems. The removal efficiencies, effects of seasonal temperature variations, and effects of increased loading rates on contaminant removal within such a system was studied by Auburn University researchers at a created wetland site in Hurtsboro, Alabama. The 0.16 ha system consisted of a two cell wetlands planted with cattails (Typha latifolia), bulrush (Scirpus validus), arrow duck potatoes (Sagitaria latifolis), burr reeds (Spargaminum eurycarpun), water pennywort (Hydrocotyl ranunculoides), and parrotfeather (Myriophyllum brasiliense). Testing occurred from January through September of 1988 at hydraulic loading rates of 169, 289, and 345 m³ ha^?1 d^?1. The monthly average total suspended solids influent: effluent mg L^?1 concentration ratio during the study period was 135:19 while the monthly average total BOD₅ influent: effluent mg L^?1 concentration ratio was 38:8. Once the system stabilized, the monthly average total BOD₅ effluent concentration remained essentially constant over the range of average BOD₅ loading rates employed in this study. Total Kjeldahl N removal was more effective at loading rates of 2.6 kg ha^?1 d^?1. The monthly average influent: effluent TKN mg L^?1 concentration ratio was 15:4.