Volume 11 Issue 4
Evaluation of Hydraulic Retention Time on Treatment of Coffee Processing Wastewater (CPWW) in EGSB Bioreactor
Abumalé Cruz-Salomón, Edna Ríos-Valdovinos, Francisco Pola-Albores, Selene Lagunas-Rivera, Rocío Meza-Gordillo and Víctor M. Ruíz-Valdiviezo
1Faculty of Engineering, University of Science and Arts of Chiapas, Libramiento Norte Poniente No. 1150, Lajas Maciel, Tuxtla Gutiérrez C.P. 29039, Mexico
2Center for Research and Technological Development in Renewal Energies, University of Science and Arts of Chiapas, Libramiento Norte Poniente 1150, Lajas Maciel, Tuxtla Gutiérrez C.P. 29039, Mexico
3Professor CONACYT, Department of Chemical and Biochemistry Engineering, National Institute of Technology of Mexico-Tuxtla Gutiérrez Institute of Technology, Carretera Panamericana Km 1080, Tuxtla Gutiérrez C.P. 29050, Mexico
4Department of Chemical and Biochemistry Engineering, National Institute of Technology of Mexico-Tuxtla Gutiérrez Institute of Technology, Carretera Panamericana Km 1080, Tuxtla Gutiérrez C.P. 29050, Mexico
*Authors to whom correspondence should be addressed.
Abstract
The coffee processing agro-industry generates large quantities of wastewater requiring systematic treatment prior to disposal. For this reason, the aim of this study was to evaluate the hydraulic retention times (HRT) in treatment of coffee processing wastewater (CPWW) using a laboratory scale Expanded Granular Sludge Bed (EGSB) bioreactor at different HRT (3 to 9 days). The EGSB was evaluated in mesophilic condition (26 ± 2 °C) with an average pH of 7.5 ± 0.2 to determine the chemical oxygen demand (COD) removal efficiency. According to the results, the COD removal efficiency increases from 94 to 98% when the HRT increase from 3 to 9 days; the α factor remained stable (0.98) throughout the evolution of the bioreactor. The HRT´s between 7–9 days generated effluents capable to be dischargeable into water bodies with a permitted COD concentration according to World Health Organization (WHO) and Official Mexican Environmental Regulations permissible limits. Results evidenced that the HRT of 9 days was the one that greater COD removal generated, so the EGSB bioreactor can be a sustainable alternative to solve the environmental problems, compared to other conventional methods to CPWW treatment.
Keywords:anaerobic EGSB reactor; coffee processing wastewater; HRT; chemical oxygen demand; wastewater treatment