Document Type : Research Paper
Authors
1
Facultad de Ingeniería. Universidad de Ciencias y Artes de Chiapas. Libramiento Norte Poniente 1150. Lajas Maciel, Tuxtla Gutiérrez, C.P. 29039, Chiapas, México.
2
Departamento de Ingeniería Química y Bioquímica, Tecnológico Nacional de México-Instituto Tecnológico de Tuxtla Gutiérrez, Carretera Panamericana Km 1080, Tuxtla Gutiérrez, C.P. 29050, Chiapas, México.
3
Centro de Investigación y Desarrollo Tecnológico en Energías Renovables, Universidad de Ciencias y Artes de Chiapas, Libramiento Norte Poniente 1150, Lajas Maciel, Tuxtla Gutiérrez, C.P. 29039, Chiapas, México.
4
Catedrática CONACYT, Tecnológico Nacional de México-Instituto Tecnológico de Tuxtla Gutiérrez. Carretera Panamericana Km 1080, Tuxtla Gutiérrez, C.P. 29050, Chiapas, México.
Abstract
Untreated agro-industrial wastewaters are undesirable in the aquatic environment due to the presence of high organic matter contents. However, they may constitute a large potential for biogas production. The present investigation is focused on three laboratory-scale anaerobic expanded granular sludge bed (EGSB) bioreactors, continuously operated for 60 d under mesophilic condition with the aim of exploring the feasibility of treating three most significant agro-industrial wastewaters in Chiapas, Mexico (i.e., cheese whey, vinasse, and coffee-processing wastewater). The EGSB bioreactors were operated with a hydraulic retention time (HRT) of 6 d under stable conditions (i.e., buffer index (BI) of 0.31, 0.34, and 0.03), generating a maximum chemical oxygen demand (COD) removal efficiency of 91, 74, and 96% with an average methane production of 340, 245, and 300 mL/g COD∙d for cheese whey, vinasse, and coffee-processing wastewater, respectively. According to the obtained results, the EGSB bioreactors could be a sustainable alternative to simultaneously solve the environmental problems and to produce bioenergy.
Graphical Abstract

Highlights
- Anaerobic EGSB bioreactors were successfully performed for treating different agro-industrial wastewaters.
- COD removal of upto 91, 74, and 96% for cheese whey, vinasse, and coffee-processing wastewater, respectively.
- CH4 yield of 340, 245, and 300 mL/gCOD∙d for cheese whey, vinasse, and coffee-processing wastewater, respectively.
- Biogas generated contained 63.5, 70.8, and 80.3% CH4 for cheese whey, vinasse, and coffee-processing wastewater, respectively.
Keywords