A review on upflow anaerobic sludge blanket reactor: Factors affecting performance, modification of configuration and its derivatives. (5th January 2022) - Mariraj Mohan, S.
Abstract: The upflow anaerobic sludge blanket (UASB) reactor can be considered as one of the promising anaerobic wastewater treatment technologies suitable for the treatment of high‐strength wastewater. In the recent period, researchers have focused on the treatment of low‐strength wastewater using this technology. This review focuses on the key factors affecting the reactor performance such as hydraulic retention time (HRT), temperature, organic loading rate (OLR), pH and alkalinity, granulation, wastewater characteristics, mixing, and modification to conventional configuration. Start‐up and granulation played a major role in the determination of reactor performance, and various theories have been proposed to understand the mechanism of granulation. Correlation between start‐up time and OLR was found to be low, as other operating parameters might have been influencing the start‐up time. Flowchart depicting the development of UASB reactor over time is included. In the present work, further development and derivatives of the UASB reactor such as static granular bed reactor (SGBR) and expanded granular sludge bed (EGSB) reactor are analyzed. The optimal conditions for UASB for treating various types of substrates was found to be HRT of 3–24 h, OLR of 1–15 kg COD/m 3 /d, and operational temperature in mesophilic range (30–40°C). Analysis of various modifications that pave the way for identification of future areas of research to improve reactor performance is also presented. Abstract : The figure shows a schematic view of the conventional UASB reactor, and to improve the performance of the reactor, development of granules should be given more importance. To make the granules suitable for the reactor, start‐up has to be initiated. Furthermore, factors affecting performance of the reactor were also discussed. To improve the performance furthermore, various modifications of UASB by imposing variations in configuration were tried. It also shows schematic view of EGSBR and SGBR (derivatives of UASB). Practitioner Points: Governing factors for better operating conditions are presented. Attaining start‐up with respect to various substrates is discussed. Factors responsible for increase in efficiency, further developments and derivatives of UASB are depicted.