engleski

The Use of Constructed Wetland for Dye-house Waste Waters Treatment- Ajdovščina, Slovenija (Research within Eureka Textilwet E!2983 Project)

Wet processes employed in modern textile industry require water of a very good quality concerning the amount of suspended solids, dyes or detergents. Also, legislation concerning ecology imposes great demands when discharge of toxic materials is in question, which means ensuring a better performance of waste water treatment and water recycling. The emission of sewage from the communities, small industrial plants and dumping-sites has not been solved until today. Not before recently we recognized the real value of the wetland ecosystem also from the point of view of their self-clearing capacities. Therefore, development of alternative technologies as constructed wetlands (CW) for waste water treatment (WWT) was initiated. CWs have many advantages such as low construction and operation costs, simple installation and maintenance. Today, they represent a “ greening” trend in environmental engineering in Slovenia, where over 50 CW were designed and constructed. CWs are being used for both small and large applications. Variations of this technology are in use to deal with single-family residences to highway runoff, landfill sites, food processing industries, and settlements up to 1000 PE. On the basis of treatment efficiency, it is evident that the CW is ecologically acceptable small WWT technology. The idea of WWT in the lagoons with floating plants and later in the CW came to us in the second half of the eighties (Bucksteeg et al., 1987). The experiences with floating plants showed that the CWs are more suitable than lagoons by many reasons (cold winters, potential odours and insects, large areas needed). An experimental period of treating wastewater in CW followed. During this period we based on experiences on some European researchers (Kickuth 1984 and Clayton, 1988). Later on we introduced our own experiences to the technology, primarily regarding the geographical, demographical and water management characteristics of Slovenia. From 1989 to 2005 Limnos constructed 32 systems in different regions in Slovenia. Systems were designed on the basis of hydraulic and pollution loads, and Slovenian regulations for discharging the effluent into the receiving waters (OG RS, 35/96). The media has an important role in treatment of wastewater therefore different mixture in each system in accordance with organic loads was selected. In the early systems we followed the guidelines issued by Cooper (1990). The main attention was paid to prevent clogging. Theoretical hydraulic loading of media was in each case at least 10-3 m/s. The basic design criteria were based on a project started in 1991 in Austria (Perfler and Haberl, 1992), which was modified through selection, application and comparison of various options in situ (Urbanc-Bercic et al., 1998). After 1995, cleaning sumps and drainages, mechanical system for exchanged water flow in the vertical beds, and combination between vertical and horizontal flow within one bed were introduced into the systems. Vertical and horizontal flow (VF, HSF) was examined in 10 systems. In others, which consist of one or more interconnected beds, the flow was horizontal. CWs were installed to treat sewage, landfill leachate, industrial wastewaters, and motorway run-off. A Constructed Wetland System for the treatment of dye-house waste waters from Textina textile factory has been designed and constructed in Ajdovščina, Slovenia. In this paper, a model scale experiments (carried out at Faculty of Textile Technology in Zagreb, Croatia and Faculty of Mechanical Engineering, University of Maribor, Slovenija) for the optimisation of CW (Limnos) performance for the treatment of dye-house waste waters, are shown. Obtained results of the preliminary investigations directly influenced the design and construction of the pilot CW system. Also, in order to determine the efficiency of the process, two types of model dye-stuff (mixture), belonging to reactive and vat group, were used. Parameters measured and used for the evaluation of the waste water quality before and after the purifying process were COD, BOD5, TOC, AOX, el. conductivity, pH, degree of decolouration and the amount of Cl- ions. Obtained biological parameters were determined by standard methods and should be within the limits regulated through the legislation.

constructed wetland; biological parameters; dye-house waste waters

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