E FFECTIVENESS OF DOMESTIC WASTEWATER TREATMENT IN THE “ G RMEČ ” TEACHING CENTER USING PILOT-SCALE CONSTRUCTED WETLAND AS UNCONVENTIONAL METHOD

Environmental care, higher requirements for quality of effluent, high cost of conventional wastewater treatment, and increased energy costs required for their work, have led scientists to more comprehensive research on a possibility of using a constructed wetland in wastewater treatment technology. Constructed wetlands are artificially shaped swamps with the aim of creating conditions conducive to the purification of wastewaters flowing through them. They are used for treatment of municipal wastewater from small settlements and a small industrial facility, as well as other types of wastewater. The educational pilot scale constructed wetland on which the research was conducted is located in the area of Bihać municipality, on a plot used by the Biotechnical Faculty in Bihać. The pilot scale constructed wetland for wastewater treatment covers an area of 20 m2 and is dimensioned for 10 equivalents of population. In this research we have examined the effectiveness of domestic wastewater treatment in the "Grmeč" Teaching Center using pilot scale constructed wetland. Plants planted in the constructed wetland were Typha latifolia and Phragmites australis, and the substrate was made of sand and pebbles of different granulations. The recipient of purified wastewater is the Drobnica stream, which is about 10 m away from the site. The research was conducted in May, with the flow varied depending on a weekly student workload. Efficiency of purification using constructed wetland depended on flow rate and organic wastewater load, ranging from 37.15% at a minimum flow of 9.89x10-6 m3/s and HPK values of 35 mgO2/L, up to 89.48% at the highest flow value of 2.51x10-5 m3/s, and HPK values of 189 mgO2/L. The highest concentration of ammonia in the influent was 145.62 mg N/L, and the lowest concentration of ammonia in the effluent was 6.31. mg N/L.