Enzymatic pre-treatment for enhancement of primary sludge fermentation

Gholamreza Bahreini; Laleh Nazari; Dang Ho; Christopher C Flannery; Elsayed Elbeshbishy; Domenico Santoro; George Nakhla

doi:10.1016/j.biortech.2020.123071

Enzymatic pre-treatment for enhancement of primary sludge fermentation

Bioresour Technol. 2020 Jun:305:123071. doi: 10.1016/j.biortech.2020.123071. Epub 2020 Feb 22.

Authors

Gholamreza Bahreini¹, Laleh Nazari², Dang Ho³, Christopher C Flannery⁴, Elsayed Elbeshbishy⁵, Domenico Santoro⁶, George Nakhla⁷

Affiliations

¹ Department of Civil and Environmental Engineering, Western University, London, ON, N6A 5B9, Canada.
² Department of Chemical and Biochemical Engineering, Western University, London, ON, N6A 5B9, Canada.
³ Suez Water Technologies and Solutions, Oakville, ON, L6M 4B2, Canada.
⁴ Novozymes Biologicals, Inc., Salem, VA, 24153, United States.
⁵ Civil Engineering Department, Ryerson University, Toronto, ON, M5B 2K3, Canada.
⁶ Trojan Technologies, London, ON, N5V 4T7, Canada; Department of Chemical and Biochemical Engineering, Western University, London, ON, N6A 5B9, Canada.
⁷ Department of Civil and Environmental Engineering, Western University, London, ON, N6A 5B9, Canada; Department of Chemical and Biochemical Engineering, Western University, London, ON, N6A 5B9, Canada. Electronic address: gnakhla@uwo.ca.

PMID: 32114298
DOI: 10.1016/j.biortech.2020.123071

Abstract

This research showed the interrelated impact of cellulase enzyme, temperature, and SRT on enhancement of primary and rotating belt filter (PS, RBF) sludges fermentation. SRTs of 1, 2, and 4-days were tested at 25 °C and 35 °C. Enzymatic enhancement was examined using three different doses of enzyme (i.e. 0.5%, 1%, and 1.5% of the total solids in the feed). The results showed a positive impact of enzyme dose as well as temperature and SRT on VFA and soluble COD production. For the RBF sludge, enzyme addition enhanced the VFA yield of fermentation at room temperature (25 °C) from 52-103 mgCOD/g VS to 93-188 mgCOD/g VS, as compared with increase from 78-192 to 87-202 mgCOD/gVS in PS. Intensification of the fermentation process, particularly for the cellulose-rich RBF sludge, by enzyme addition confirms process viability as an alternative to the extraneous carbon sources for biological nutrient removal in wastewater treatment plants.

Keywords: Biological nutrient removal; Enhanced fermentation; Enzymatic pre-treatment; Primary clarifier; Rotating belt filter.