Available online at www.sciencedirect.com Journal of Hazardous Materials 155 (2008) 76–82 The use of constructed wetland for dye-rich textile wastewater treatment Tjaˇ sa G. Bulc a , Alenka Ojstrˇ sek b,∗ a LIMNOS Company for Applied Ecology, Podlimbarskega 31, 1000 Ljubljana, Slovenia b University of Maribor, Faculty of Mechanical Engineering, Textile Department, Smetanova 17, 2000 Maribor, Slovenia Received 30 July 2007; received in revised form 12 November 2007; accepted 12 November 2007 Available online 23 November 2007 Abstract 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 m 3 /day, covering 80 m 2 , 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%, BOD 5 66%, TOC 89%, N total 52%, N organic 87%, NH 4 -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. © 2007 Elsevier B.V. All rights reserved. Keywords: Coloured textile wastewater; Constructed wetland; Phragmites australis 1. Introduction Coloured textile effluents represent severe environmental problems as they contain mixture of chemicals, auxiliaries and dyestuffs of different classes and chemical constitutions with elevated organic parameters such as chemical oxygen demand (COD), total organic carbon (TOC), adsorbable organic halo- gens (AOX), inorganic parameters such as metals, chloride, sulphate, sulphide and nitrogen. A literature review regarding dye-bath wastewater treatments reveals the consideration of dif- ferent approaches to handling such effluents, which include biodegradation, adsorption, advanced oxidation and membrane filtration [1–5]. Choosing the most appropriate treatment method or combination depends on the nature and the amount of effluent from textile processing plant. In the past few years, we became aware that systems imi- tating the self-cleaning ability of natural wetland ecosystems by establishing optimal physical, chemical and biological con- ∗ Corresponding author. Tel.: +386 2 220 7935; fax: +386 2 220 7990. E-mail address: alenka.ojstrsek@uni-mb.si (A. Ojstrˇ sek). ditions for in situ wastewater treatment should be considered with greater importance [6]. Constructed wetland (CW) is an example of such system that is also simple to use, environmen- tally friendly, with low construction and operational costs, and efficient enough to treat diverse wastewaters, although the expe- rience in treating textile wastewaters is limited. CW’s designs differ regarding to the type of flow and applied bed material [7,8]. The removal efficiencies of natural systems could be exceed- ingly variable, and influenced by numerous parameters such as water/bed material temperature, air temperature, sedimenta- tion, pollutant concentration, and vegetation. These parameters cause changes in uptake or release of chemical substances, and biochemical activities of microorganisms and plants. Methods of decolourisation of dyes, reported by a number of researchers [1–5], are often not feasible for treating dye- rich wastewater because of technology intensiveness, reliable power demand, and complexity of components, unproven long- term effectiveness and high investment and maintenance costs [9]. Promising results of CW recorded in last few years for industrial wastewater and lacking of literature on textile wastew- ater treatment with CW conducted us to research the viability of treating dye-rich wastewater with CW. The main objective 0304-3894/$ – see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.jhazmat.2007.11.068