Various Reactor Types for Biodegradation Process

Abstract

In last few decades, biological treatment of toxic pollutants and industrial wastewater has gained tremendous attention in the scientific community as well as in the industrial arena. Consequently, various kinds of reactor configuration for biodegradation process, starting from the more conventional activated sludge system to highly advanced microbial fuel cell (MFC) or hollow fiber membrane bioreactor, have been reported in the literature. Batch or semi-batch reactors are mainly used for laboratory studies, anaerobic digestion and manufacture of pharmaceuticals; while continuous reactors are often employed for aerobic treatment of municipal and industrial wastes [1]. Two extreme mixing regimes are represented by well stirred tank reactor and plug flow reactors. Intermediate degrees of mixing can be achieved by employing well-stirred reactors in series or by designing plug flow reactors with axial dispersion. The overall model of the reactor can be developed by combining the equations for the hydraulic regime and the kinetics of the reactions [1]. As compared to the suspended culture of free microbial cells, the immobilization process affects the bioreactor performance by providing the retention of active biomass on support particles, flexibility of reactor design and the improved thermal and operational stability [2]. A brief account of major types of bioreactors with their successful application in the biodegradation of wastewaters, especially the phenolic pollutants and effluents of petroleum/oil based industries, is presented in the following sections. A more detail and excellent review is reported by Al-Khalid & El-Naas [3].