THERMOPHILIC BIOMETHANE PRODUCTION BY VINASSE IN AN AnSBBR: START-UP STRATEGY AND PERFORMANCE OPTIMIZATION

Juliane N De Albuquerque,Suzana M Ratusznei,Marcela R Orellana,José A D Rodrigues

doi:10.1590/0104-6632.20190362s20170611

Juliane N De Albuquerque, Suzana M Ratusznei + Show 2 more

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https://doi.org/10.1590/0104-6632.20190362s20170611

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Abstract

Abstract Thermophilic anaerobic digestion treatment of industrial wastewater generated at high temperatures can be used as an alternative for environmental pollution control and bioenergy production. Therefore, this study investigated thermophilic anaerobic reactors containing immobilized biomass (AnSBBR) to treat vinasse for methane production, in batch and fed-batch mode, in a three-step approach. In Step I (batch), the biomass was properly adapted to the thermophilic condition (55 °C) with a feed containing vinasse plus molasses as a co-substrate. In Step II (batch), the applied volumetric organic load (AVOL) was increased and resulted in a methane molar productivity of 304 molCH4.m-3.d-1 at an AVOL of 25.9 gCOD.L-1.d-1 and a yield of methane per removed organic matter near 331 NmL-CH4.gCOD-1. In Step III, a fed-batch strategy was employed at an AVOL of 25.1 gCOD.L-1.d-1 and achieved an optimum methane productivity of 352 molCH4.m-3.d-1 with COD and carbohydrate removal efficiencies of approximately 80 % and 90%, respectively. A kinetic model fitted to the experimental data allowed better understanding of the anaerobic metabolic reactions. Finally, the results obtained demonstrated that a thermophilic AnSBBR is an efficient technological alternative for methane production through vinasse digestion.

Highlights

Environmental problems inherent in the exploration and use of fossil fuels have stimulated the development of biofuels, such as ethanol, which can be obtained from different sources (Wilkie et al, 2000; Gamboa et al, 2011)
The stability of the system was confirmed by the results of bicarbonate alkalinity and acids accumulation in the reactor, which were 647 mgCaCO3.L-1 and 504 mgHAc L-1, respectively
The results indicated that the biomass was adhered to the inert support and was adapted to the temperature of 55 oC and influent concentration of 5000 mgCOD.L-1 with molasses-based wastewater

Summary

Introduction

Environmental problems inherent in the exploration and use of fossil fuels have stimulated the development of biofuels, such as ethanol, which can be obtained from different sources (Wilkie et al, 2000; Gamboa et al, 2011). This problem, allied to the growing volume of generated vinasse, has stimulated the search for technologies that reduce the polluting potential of vinasse without losing its nutritive properties. One of these technologies is the anaerobic reactor operated in batch and fed-batch mode (AnSBBR) which has presented promising results regarding environmental compliance and energy recovery from wastewaters. These reactors are indicated for wastewaters with high organic load and nutritive characteristics, such as vinasse, because nutrient properties are conserved even after treatment, which enables further use as fertilizer (Vlissidis and Zouboulis, 1993; Barros et al, 2016)

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