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Innovative Technology For Wastewater Treatment In Rural Communities.

Congress: 2015
Author(s): Juan Vigueras Cortes (Durango, Mexico)


Keyword(s): Sub-theme 4: Infrastructure development,
AbstractVigueras-Cortés J.M*., Villanueva-Fierro I*. and Garzón-Zúñiga M.A*. *Centro Interdisciplinario de Investigación para el Desarrollo Integral Regional, CIIDIR IPN Unidad Durango. Sigma 119, Fracc. 20 de Noviembre II, 34220, Durango, Dgo., México. (52)55 57 29 6000 ext 82602, (52)618 814 2091 mviguer@ipn.mx Introduction: In the world there are many rural communities under 5,000 inhabitants, who do not have an adequate wastewater treatment system. These conditions raise the epidemiology of gastrointestinal illness in vulnerable population, and augmented by the environmental pollution caused by undesirable odors around the house, vector development and runoff into the creek from the streets. As an alternative to reduce this problem, an innovative technology was developed to treat wastewater with organic biofilter using agave fiber as material support. These are characterized by an economic system, simple and easy operation, and minimal cost of set-up, start-up monitoring and control. Agave fiber is a byproduct of mescal production, a spirituous beverage obtained from the fermentation of sugars extracted from the maguey plant (Agave durangensis). Agave fiber is obtained from the cooked stems of the plant that actually are a waste. The mescal is produced in Durango, a State of Mexico, with more than three millions of A. durangensis, so that the availability of the agave fiber is not a problem. Methods/Material: Two series of three laboratory-scale biofilters (BFs) were packed with agave fiber to remove organic matter, expressed as biochemical oxygen demand at five days (BOD5) and chemical oxygen demand (COD); pathogen microorganisms as fecal coliform (FC) and Helminthes egg (HE); and suspended material as total suspended solids (TSS) with five different hydraulic loadings (HL) (0.27, 0.54, 0.80, 1.07 and, 1.34 m3m-2d-1). BOD5, COD, TSS and FC were measured according to the Standard Methods (APHA, 1995), respectively. HE by NOM-003-SEMARNAT-1997. The first series was tested with an aeration rate of 0.62 m3m-2h-1 and the second series was tested without air. To avoid compaction of the filter material a support was placed as internal structure of 4, 8 and 12 acrylic plates for each series of biofilters. Hydraulic head loss in the aerated biofilter and the internal temperature of each biofilter were measured. Cellulose, lignin and acid detergent fiber were analyzed in agave fiber to predict the estimated time use as filter material. The system performance was evaluated during 510 days. Results and discussion: At the beginning of the study, the agave fiber was composed of 55.0% cellulose, 10.7% lignin and 66.5% acid detergent fiber. At the end of the aerated and unaerated biofilters studies, cellulose was reduced to 46.3 and 45.3%; lignin increased to 32.4 and 34.0%, and acid detergent fiber increased to 79.1 and 79.4%, respectively. The fiber has a density of 0.36 gcm-3 and has void spaces that make up 82% of the total volume. At an HL of 0.80 m3m-2d-1, the removal efficiencies of the aerated biofilters were 92.0% of biochemical oxygen demand, 79.7% chemical oxygen demand, 98.0% helminthes eggs, 99.9% fecal coliforms and 91.9% total suspended solids. Statistical analysis showed that the chosen operational parameters significantly influenced the removal efficiencies of the biofilters. The effluent quality obtained under these conditions complied with the Mexican and US EPA standards (USA-EPA, 2004) for agricultural irrigation and green spaces, except for coliforms, and the effluents must be disinfected. Conclusion: In the composition of agave fiber, the cellulose was degraded by 18.1% in aerated biofilters and 15.8% in the no aerated biofilters after 517 days of continuous operation.This difference was potentially caused by the greater removal efficiency of the cellolytic bacteria and fungi under aerobic conditions tan under anaerobic conditions (Pérez et al, 2002).The use of agave fiber as a packing material in the biofiltration process is adequate for the biological removal of pollutants from municipal wastewater. The treated water met the Mexican and US standards. Thus, the treated water could be reused in agriculture and green spaces irrigation and could be safely discharged into lakes if the effluents are disinfected. Agave fiber serve as a good support of biomass because they exhibited low cellulose biodegradation in biofilters due to its high porosity, low cost, regional availability, and could potentially last during five years, similar to the obtained by Schmidt et al., (2004). The maximum HL for both biofilters series, to fulfil the Mexican and US EPA regulation for BOD5, was 0.80m3m-2d-1, but the effluents need disinfection to comply with the coliforms norm. The best results were observed in the BFs with four separation plates and temperatures above 21°C. During this study, the systems had pressure drops below 0.5 mm H2O. It is concluded that agave fiber is a favorable choice for use as a packing material in biofiltration process, and this is a novel technique that can be applied to small generators. 1. Pérez, J., Muñoz-Dorado, J., de la Rubia, T. and Martínez, J. (2002). Biodegration and biological treatments of cellulose, hemicellulose and lignin. An overview. Int. Microbiol 5:53-63 2. Schmidt, D., Janni, K. and Nicolai, R. (2004). Biofilter design Information. University of Minnesota, BAEU-1. USA. 3. USA-EPA. (2004). Manual- Guidelines for water reuse. EPA/625/R-04/108. U.S. Agency International Development, Washington, DC.
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