نوع مقاله : یادداشت فنی
نویسندگان
دانشکدهی مهندسی، بخش مهندسی راه و ساختمان و محیط زیست، دانشگاه شیراز
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
Waste stabilization ponds have been extensively used in the world for wastewater treatment. Due to their low cost and simplicity of operation and maintenance, stabilization ponds predominate among the small wastewater treatment systems. The low TSS removal efficiency of wastewater stabilization ponds is mainly due to the growth of algae in the maturation ponds. Aquatic plants, such as duckweed, can be successfully used to control algae in wastewaters. Consequently, the use of a modified type of waste stabilization ponds with a floating layer of duckweed on the surface has received growing attention. Duckweed is a floating aquatic plant within the family Lamnaceae that can easily be harvested, providing a potential economic resource as a dietary supplement and nutrient source for livestock. The major mechanism of duckweed plants in the reduction of algal growth is covering the wastewater surface to reduce light penetration. Accordingly, duckweed plants were used in this study. Wastewater effluent collected from maturation pond of Bushehr stabilization pond system was used to evaluate the duckweed plants' efficiency in improving the effluent quality, especially control of algal growth, in a field pilot. The pilot system including two ponds, the duckweed (Lemna gibba L.) inoculated treatment pond and the control one, was constructed under local outdoor natural conditions. Each pond had dimensions of 3m length, 0.5 m width, and 0.5 m depth. The system operated in a continuous mode with a residence time of 15, 10, and 5 days and TSS, COD, pH, EC, $NO_{3}^{-}$,$PO_4^{3-}$; total and fecal coliform was measured. The removal efficiency of duckweed pond was 64\%-90\% for TSS, 46\%- 56\% for COD, 41\%-51\% for $NO_3^-$, 58\%-71\% for $PO_4^{3-}$, 97.2\%-98.7\% for total coliform, and 95.9\%-99.2\% for fecal coliform. The results show that duckweed plants were able to considerably improve the effluent quality, especially for TSS removal.
کلیدواژهها [English]
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