Enhanced biogas production and substrate degradation through the intermittent operation of modified upflow anaerobic sludge blanket-static granular bed reactor series

In the present study, the performance of a modified upflow anaerobic sludge blanket (MUASB) reactor-static granular bed reactor (SGBR) series in intermittent operation was analyzed for the treatment of synthetic wastewater. The reactor series was operated with a hydraulic retention time (HRT) of 24 h. The maximum chemical oxygen demand (COD) removal and biogas production of the reactor series obtained during the intermittent operation were 99 ± 0.29% and 0.529 ± 0.03 m³ /kg COD_digested , respectively. One-way analysis of variance (ANOVA) indicated a significant difference in biogas production during continuous and intermittent operations, whereas the COD removal was similar. Intermittent operation of the reactor series yielded a 56.05% increase in biogas production when compared with the continuous operation. The reactor series was maintained stable throughout the operational period. The maximum total suspended solids (TSS) removal and total nitrogen (TN) removal of the reactor series during the intermittent operation were 91.67% and 72.37%, respectively. Intermittent operation of the reactor series can be considered advantageous because of the reduced operational cost and enhanced biogas production in addition to COD removal. PRACTITIONER POINTS: Intermittent operation of MUASB-SGBR series in terms of COD removal is evaluated. COD removal of reactor series was similar in intermittent and continuous operation. Biogas production in intermittent operation was superior to continuous operation. Reactor series performance is also compared with continuous operation using one-way ANOVA.

A review on upflow anaerobic sludge blanket reactor: Factors affecting performance, modification of configuration and its derivatives

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/m³ /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.