Removal of Methylene Blue dye from textile wastewater using vertical flow constructed wetland

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The aim of this study is to assess the performance of vertical flow constructed wetland system to treat synthetically prepared textile wastewater containing Methylene Blue dye (MB) of two different dye concentrations of 50 mg/L and 100 mg/L. Three lab scale Vertical Flow Constructed Wetland systems (CW1, CW2 and CW3) of size 30 cm diameter and 60 cm depth each were fabricated. CW1, acted as a control system without plants and was packed with sand, zeolite and gravel. CW2 and CW3 were planted with wetland plants - Canna Indica. CW2, was filled with packing media: sand, zeolite and gravel and CW3, with sand and gravel. The wetlands were operated in batch and continuous mode. The systems were evaluated by measuring Colour removal, Chemical Oxygen Demand (COD), pH and Electrical Conductivity (EC). The absorbance of the Methylene Blue dye in the wastewater before and after treatment was measured at the wavelength of maximum absorption using UV/visible spectrophotometer. The results showed that the wetlands CW1, CW2 and CW3 reduced colour by 85 %, 93 % and 74 % for 50 mg/L of MB and 89 %, 99 % and 74 % respectively for 100 mg/L of MB. COD removal of 70 %, 93 % and 89 % was achieved in CW1, CW2 and CW3 respectively for 50 mg/L MB. At 100 mg/L MB, COD removal was 65 %, 89 % and 83 % in CW1, CW2 and CW3 respectively. This study shows that the constructed wetland system with zeolite is a promising technique for the colour removal of methylene blue dyeing textile effluents.