Abstract—For many years, sewage sludge has been processed
for methane production in anaerobic digestion reactors at
wastewater treatment plants around the world. Sewage sludge
is produced in large quantities and is rich in biodegradable
organic materials, from which sugars (e.g., glucose) can be
produced, recovered and used as a substrate to support
hydrogen production through the Dark Fermentation (DF)
process. DF is one of several methods used for bio-hydrogen
production, whereby fermentative bacteria are used to
hydrolyse organic substrates to produce hydrogen gas.
Carbohydrates (sugars) is one of the main fermentable
substrates for hydrogen production, and they are considered
the most favourable substrate for fermentative bacteria (e.g.,
Clostridium bacteria). Although sewage sludge is rich in
organic materials, still the complexity of its structure and low
carbon/nitrogen ratio limits the bio-hydrogen production via
DF processes. Therefore, this paper addresses the impact of
Enzymatic Hydrolysis (EH) as a pre-treatment of sewage sludge
on enhancing the biodegradability and glucose content in
sewage sludge. The result shows that using the EH process as
pre-treatment for sewage sludge, enhanced the glucose content
in sewage sludge and converted some of the macro sewage flocs
to easy digestible micro flocs (glucose). Therefore, the substrate
being more favourable and easier to digest by bacteria in the DF
reactor, enhanced the production of hydrogen and VFAs. More
research needs to be done to find the optimum enzyme dosage,
initial substrate concentration and operation temperature
(especially when the enzyme is used inside the DF reactor).
Index Terms—Anaerobic digestion, dark fermentation, enzymatic hydrolysis, sewage sludge.
Saleh Al-Haddad is with Kuwait Institute for Scientific Research, Kuwait City, Kuwait (e-mail: email@example.com).
Cynthia Okoro-Shekwaga, Louise Fletcher, and Miller Alonso Camargo-Valero are with University of Leeds, Leeds, UK (e-mail: firstname.lastname@example.org, email@example.com, firstname.lastname@example.org).
Cite: Saleh Al-Haddad, Cynthia Kusin Okoro-Shekwaga, Louise Fletcher, and Miller Alonso Camargo-Valero, "The Impact of Enzymatic Hydrolysis of Sewage Sludge as a Pre-treatment for Dark Fermentation," International Journal of Environmental Science and Development vol. 13, no. 6, pp. 279-286, 2022.
Copyright © 2022 by the authors. This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).