Effect of the Progressive Increase of Organic Loading Rate in an Anaerobic Sequencing Batch Reactor for Biodiesel Wastewater Treatment

Erlon Pereira,Alisson Borges,Greicelene Da Silva

doi:10.3390/w14020223

Abstract

The wastewater from the biodiesel industry is an environmental problem, and from a sanitation resources perspective, the anaerobic sequencing batch reactor (ASBR) is an interesting alternative for wastewater treatment. A better understanding of ASBR operation behavior under the progressive increase of the organic loading rate (OLR) is crucial for upscaling. The objective of this study was to monitor an ASBR operating with an OLR ranging from 1.3 to 9.3 kgCOD m−3 d−1. The average chemical oxygen demand (COD) removal efficiencies of the ASBR were 52, 41, 47, and 11% for phases 1, 2, 3, and 4, respectively. The apparent kinetic coefficient, i.e., the rate of degradation of organic matter, was between 0.10 and 1.80 h−1, considering the kinetic model that considers the residual substrate concentration, which was the one that best fit the obtained data. The progressive increase in applied OLR modified the microbial biomass diversity, which in turn influenced the degradation kinetics of the organic matter. In addition, the values of the applied OLR of 5.1 kgCOD m−3 d−1 and a food to microorganism ratio (F/M) of 0.6 kgCOD kgVSS−1 d−1 were shown to be limiting values that promoted the overload of ASBR.

Highlights

Biodiesel, as a result of extensive scientific research, has emerged as a potential replacement for fossil fuels
The objective of this study was to evaluate the performance of an anaerobic sequencing batch reactor (ASBR) in terms of (i) removal efficiency of organic matter, (ii) substrate degradation kinetics, and (iii) microbiological characteristics and microbial diversity of the biomass of an ASBR operating under progressive increase of applied volumetric organic loading rate (aOLR) based on chemical oxygen demand (COD) of biodiesel wastewater within the range of values usually found at an industrial scale
The concentration of wastewater effluent was the highest at the start of Phase I; there was an improvement in the capacity of the biomass to degrade soluble organic matter over the time of operation, indicated by the increase in removal efficiency of COD (Figure 2A)

Summary

Introduction

As a result of extensive scientific research, has emerged as a potential replacement for fossil fuels. A purification process is required for the commercial viability of the high industrial cost of glycerol [2]. For this reason, it is common to mix unprocessed glycerol with other aqueous by-products, generating the so-called biodiesel industry wastewater (BW). Anaerobic treatment has been widely used in tropical countries for advantages such as low energy consumption and low sludge production. Among such processes, the anaerobic sequencing batch reactor (ASBR) offers advantages in relation to continuous treatment, due to the great process flexibility and lesser need for segregated clarifiers from the unit [3]

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Conclusion