Constructed wetlands (CWs), a cost effective technology for wastewater treatment, consist of substrates and wetland plants, which should be selected carefully to gain highest treatment efficiency. However, studies on plant growth and responses to different types of substrates are very few. This study aims to assess the effects of substrate types on growth and root morphology of Canna indicaL. and nitrogen (N) removal. Twenty-four similar sized approximately 1 month old C. indicaplants were selected and grown on different substrates (gravel, pumice and biochar). All plants were supplied with a standard growth medium to which 14 mg L-1 NH4+, 14 mg L-1 NO3-, 3 mg L-1 PO43- were added and pH was adjusted to 6.5. The growth solution was renewed every week. The plants were grown under greenhouse conditions for 45 d. Results showed that growth of C. indicawas not significantly different among treatments but differences on root morphology were found. Plants grown on pumice had the largest root diameters while plants grown on biochar had the longest roots.
Keywords
Constructed wetland; Filter media; N adsorption; Root trait; Oxygenation