Description:
<p>High levels (92 and 91%) of organic carbon were successfully removed from artificial wastewater by a laboratory-scale constructed wetland under inflow loads of 670 mg/m²●d (100 mg/d) and 1600 mg/m²d (240 mg/d), respectively. Acidification to pH 3.0 was observed at the low organic carbon load, which further inhibited the denitrification process. An increase in carbon load, however, was associated with a significant elevation of pH to 6.0. In general, sulfate and nitrate reduction were relatively high, with mean levels of 87 and 90%, respectively. However, inhibition of nitrification was initiated with an increase in carbon loads. This effect was probably a result of competition for oxygen by heterotrophic bacteria and an inhibitory effect of sulfide (S²⁻) toxicity (concentration approximately 3 mg/L). In addition, numbers of healthy stalks of ¡ uncus effusus (common rush) decreased from 14 000 to 10 000/m² with an increase of sulfide concentration, indicating the negative effect of sulfide toxicity on the wetland plants.</p>