Phytoremediation of Phosphorus and Nitrogen with Canna x generalis Reeds in Domestic Wastewater through NMAMIT Constructed Wetland

A proven method of removing contaminants from secondary wastewater being more recently embraced is bioremediation. This paper focuses on phytoremediation of excessive phosphorus and nitrogen using Canna x generalis reeds through a constructed wetland in the domestic wastewater of NMAM Institute of Technology (NMAMIT), Nitte, Udupi District, India. The 30.0m x 6.0m x 1.0m wetland was constructed as an adjoining facility to the Wastewater Treatment Plant (WTP) of the Institute, for post-secondary treatment. The reeds were transplanted over the gravel bed after being grown for 2 months in the Institution's nursery. Reeds with rhizomes measuring approximately 15cm3 were planted over the gravel just touching the roots to the effluent, at a density of 4 to 5 clumps per square meter, approximately 30-40cm apart. The compartmentalized wetland is being fed by a 4 inch pipe leading effluent from the Secondary Sedimentation tank at a Hydraulic Loading Rate (HLR) of 0.02m3s-1 and with a Retention Time (R.T) of 3hrs. Replicate Samples were obtained weekly for a period of one month from the raw wastewater inlet, constructed wetland inlet and outlet sewers, and the final effluent from the Wastewater Treatment Plant (W.T.P). Tap water from the Institute was also sampled over same period as the control. These were all subjected to Laboratory analysis for pH, Turbidity, Nitrate, Phosphate and the Phenolic compounds using APHA's Standard Method. Findings revealed that treatment with the Cannas made the Sample slightly more alkaline (pH ranged from 6.73 to 6.76); reduced the turbidity from 30NTU to 20NTU; mean concentration values of Nitrate, Phosphate and Phenolic compounds at the end of treatment were respectively reduced by 51.9, 8.9, and 1.0% respectively. The study concludes that Canna plant is very efficient in remediating Nitrogen contaminants, fairly effective on Phosphorus and incapable of removing Phenolic compound pollution. Canna x generalis is therefore recommended for Nitrogen bioremediation in domestic wastewater.