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Research And Development Of A "biofilter Ef" As Method For Wastewater Treatment

Congress: 2015
Author(s): Yenny Fernanda Urrego Pereira (Ibagué,colombia, Colombia)

Keyword(s): Sub-theme 13: Non-conventional sources of water,

Introduction: Currently, 1,230,193 ha are irrigated with river water in Colombia. In plain areas, river water flows with high levels of pollution due to the large volumes of wastewater which are continuously discharged into rivers. Therefore, population located downstream use low quality water for irrigation and human consumption. Only 27% of irrigated area apply river water properly treated. For 73% of the remaining irrigated area, the literature does not accurately report about the composition or treatment for those water sources (Ministry of Agriculture and Development, 2011). The environmental and social problems caused by the consumption of poor quality water have prompted the search for technologies that integrate an efficient production model for agricultural systems with environmentally friendly practices, offering water treatment alternatives which could improve the quality of water resources, the efficiency of production systems, and of course, enhance the quality of life of contemporary peasant. The biofilter method belongs to the set of those technologies that protect the environment, this technology consists of circulating wastewater by chambers containing earthworm populations (Eisenia foetida) to remove organic matter, total coliforms and Escherichia coli and thus, regulating the pH, EC, total or suspended solids, fats, oils and BDO (biochemical demand oxygen), resulting in treated water which complies with current legislation (Bórquez, 2005). This technique has been used in other studies and have reported benefits such as low operating costs, easy maintenance and operation, no odor, and generation of biofertilizers from humus generated during the treatment process (Miranda, 2005). The objective of this project was to implement a sustainable biological technology through the establishment of a bioremediation model called "Biofilter EF" to treat wastewater from an agricultural system and therefore optimize water resources. Method: The biofilter is formed by five tanks made of polyethylene: 1) receiver tank with a grill system where wastewater are stored and then, a first particle filter is performed, 2) solute settling tank in which only the suspended particles can continue the treatment process, 3) microfiltration tank with three layers (gravel, sand and charcoal) to filter the suspended particles, 4) Eisenia foetida container tank which earthworms carried out the biodegradation process, and 5) storage tank with an ultraviolet lamp to generate lights with wavelengths between 200 and 300 nm and thereby, conduct a disinfection process and refine the water quality in this system. Results: A series of parameters were measured in the wastewater before and after passing through the Biofilter. This parameters were: pH; Electrical Conductivity (EC); Total Dissolved Solid (TDS); total nitrogen (Nt) or sum of organic nitrogen, ammonia, nitrite and nitrate; total phosphorus (Pt) or the sum of soluble orthophosphate, inorganic polyphosphates and organophosphates; oils and fat; and total coliforms. First, a model scale of biofilter was constructed in the Laboratory of Hydraulics at University of Tolima. This scale model had the capacity to treat 10 L of wastewater. 10 Kg of earthworm were used to establish the Eisenia foetida container tank. All the bioremediation process lasted two days and required 20 kW of energy. Before passing the biofilter, wastewater had a pH of 8.8, EC of 2.8 dS/m, TDS of 1,4 mg/L, Nt of 40 mg/L, and Pt of 14 mg/L. Likewise, oils and fat ranged between 60 and 68 mg/L, and total coliforms were 6000/10 ml. While, after passing the biofilter, these variables changed, in this case, pH was 7, EC was 1.8 dS/m, TDS was 0.9, Nt was 15 mg/L, Pt was 2 mg/L, oils and fat were 40 mg/L and total coliforms were 4000/10 ml. Conclusions: The results of this study suggest that the Biofilter EF technique could be a method to treat wastewater in agricultural zones with problems of low quality irrigation water because those treated water could meet current legal requirements after being subjected to the process of bioremediation carried out by E. foetida. The long duration of the treatment cycle and the energy requirements of the process indicate that this technique should be deeply studied and developed in future research. Bórquez, Y. P. H. 2005. Anteproyecto de construcción para aplicación de lombricultura al tratamiento de planta llau-llao de salmonera. Invertec SA. Universidad Austral de Chile. Chile. 189 p. Ministry of Agriculture and Development. 2011. Proyecto: desarrollo de capacidades en el uso seguro de aguas residuales para agricultura. Reporte nacional. Colombia. Miranda, P.I. 2005. Sistema Tohá: Una alternativa ecológica para el tratamiento de aguas residuales en sectores rurales.

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