The Impact of Hydraulic Retention Time and Operating Temperature on Biofuel Production and Process Wastewater Treatment


Breweries wastewater containing high concentration of organic and inorganic compounds ranks them among the top pollution generating industries. Anaerobic wastewater treatment with high organic loading rates can be achieved with lower COD strength at higher flowrates using a two-stage expanded granular sludge bed reactor. Hydraulic retention time (HRT), pH, temperature, and COD strength were varied for process optimization. Brewery wastewater with 20, 30, and 40 g COD/L as a substrate for two temperature ranges were evaluated. Under mesophilic conditions (36°C), results show COD removal efficiency (R%) and biogas production rate increased by 6% and 40% respectively as HRTs increased, maintaining a constant OLR. Results imply for equivalent OLRs, better reactor performance is achieved when running high concentration COD at slower rate compared with a lower concentration at higher rate. This implies diffusion limitation where complex proteins and fats are passed through the reactor faster than their metabolism rate in the digester. Under thermophilic conditions (50°C), results show COD removal efficiency (R%) and biogas production rate increased by 4% and 40% respectively as the HRTs increased, while maintaining a constant OLR. This implies the higher and stronger population of anaerobes are present under thermophilic condition rather than mesophilic condition.


Chemical and Biochemical Engineering

Research Center/Lab(s)

Center for High Performance Computing Research

Keywords and Phrases

Anaerobic Digestion; Chemical Oxygen Demand (COD); Hydraulic Retention Time (HRT); Organic Loading Rate (OLR)

International Standard Serial Number (ISSN)


Document Type

Article - Journal

Document Version


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© 2018 Elsevier, All rights reserved.

Publication Date

01 Jul 2018