Chapter 4 - Aerobic Granulation in Wastewater Treatment: A General Overview

Abstract

The cell–cell interaction in a microorganism is a capability of aggregation to make them self-immobilized. These self-immobilized aggregates, mostly formed in a spherical shape, are named as granules (Khan et al., 2013). The rate of oxygen flow and other physical parameters results in the formation of aerobic granules. The granule formed in the absence of oxygen categories as anaerobic granules. Aerobic granules have become the most promising tool in the wastewater treatment technologies. The treatment efficiency depends on the growth of the microorganism and settling properties. Bulk sludge with higher filamentous microorganisms causes the difficulty to settle in the clarifiers because cells naturally have the dispersion characteristic, not aggregation (Etterer, 2006). The applied adhesive force and shearing form aerobic granules which have characteristics features like more settling property (Lochmatter, 2008), high retention time (Liu et al., 2016), and high activity(Bindhu and Madhu, 2013). There are various uses of the aerobic granules in treatment process such as biodegradation of dye, Bisphenol A, fluorinated compounds, antibiotics, herbicides, pesticides, phenols, volatile organic compounds, etc. (Sarma et al., 2016). Recently, aerobic granulation is being used in paper and pulp wastewater treatment (Vashi et al., 2017). In this chapter, various aspects of the aerobic granulation are discussed such as granular characteristics, mechanism of granules formation, microbial diversity, reactors used for granulation, process parameters, and the role and application of aerobic granules in wastewater treatment.