The use of constructed wetland for dye-rich textile wastewater treatment

The objective of the present paper was to examine the treatment efficiency of constructed wetlands (CW) for the dye-rich textile wastewater with special focus on colour reduction. Preliminary, a series of dynamic experiments was performed in the CW model packed with gravel, sand, and zeolitic tuff on three synthetically prepared wastewaters using chemically differ dyestuffs, auxiliaries and chemicals, in order to investigate the potential of low-cost materials as media for textile dye-bath wastewater treatment. The obtained results evidence that applied CW model reduces colour by up to 70%, and COD and TOC by up to 45%. Based on these results, the pilot CW with vertical (VF) and horizontal flow (HF) was constructed near textile factory mainly for cotton and cotton/PES processing with intention to treat real textile wastewater in situ. It was designed for 1 m³/day, covering 80 m², packed with sand and gravel, and planted with Phragmites australis. The average treatment efficiency of the CW for the selected pollution parameters were: COD 84%, BOD₅ 66%, TOC 89%, N_total 52%, N_organic 87%, NH₄-N −331%, sulphate 88%, anion surfactant 80%, total suspended solids (TSS) 93%, and colour 90%, respectively. The results unequivocally proved that the CW could offer an optimal solution to meet the environmental legislation as well as requirements for effective and inexpensive textile wastewater treatment.