Free ammonia enhances dark fermentative hydrogen production from waste activated sludge

Wang, Dongbo, Duan, YuYing, Yang, Qi, Liu, Yiwen, Ni, Bing-Jie, Wang, Qilin, Zeng, Guangming, Li, Xiaoming and Yuan, Zhiguo (2018) Free ammonia enhances dark fermentative hydrogen production from waste activated sludge. Water Research, 133 272-281. doi:10.1016/j.watres.2018.01.051

Author Wang, Dongbo
Duan, YuYing
Yang, Qi
Liu, Yiwen
Ni, Bing-Jie
Wang, Qilin
Zeng, Guangming
Li, Xiaoming
Yuan, Zhiguo
Title Free ammonia enhances dark fermentative hydrogen production from waste activated sludge
Journal name Water Research   Check publisher's open access policy
ISSN 1879-2448
Publication date 2018-02-03
Year available 2018
Sub-type Article (original research)
DOI 10.1016/j.watres.2018.01.051
Open Access Status Not yet assessed
Volume 133
Start page 272
End page 281
Total pages 10
Place of publication London, United Kingdom
Publisher IWA Publishing
Abstract Ammonium and/or free ammonia (the unionized form of ammonium) are generally thought to inhibit the activities of microbes involved in anaerobic digestion of waste activated sludge. It was found in this work, however, that the presence of ammonium (NH4+-N) largely enhanced dark fermentative hydrogen production from alkaline pretreated-sludge. With the increase of initial NH4+-N level from 36 to 266 mg/L, the maximal hydrogen production from alkaline (pH 9.5) pretreated-sludge increased from 7.3 to 15.6 mL per gram volatile suspended solids (VSS) under the standard condition. Further increase of NH4+-N to 308 mg/L caused a slight decrease of hydrogen yield (15.0 mL/g VSS). Experimental results demonstrated that free ammonia instead of NH4+-N was the true contributor to the enhancement of hydrogen production. It was found that the presence of free ammonia facilitated the releases of both extracellular and intracellular constituents, which thereby provided more substrates for subsequent hydrogen production. The free ammonia at the tested levels (i.e., 0-444 mg/L) did not affect acetogenesis significantly. Although free ammonia inhibited all other bio-processes, its inhibition to the hydrogen consumption processes (i.e., homoacetogenesis, methanogenesis, and sulfate-reducing process) was much severer than that to the hydrolysis and acidogenesis processes. Further investigations with enzyme analyses showed that free ammonia posed slight impacts on protease, butyrate kinase, acetate kinase, CoA-transferase, and [FeFe] hydrogenase activities but largely suppressed the activities of coenzyme F420, carbon monoxide dehydrogenase, and adenylyl sulfate reductase, which were consistent with the chemical analyses performed above.
Keyword Anaerobic fermentation
Free ammonia
Waste activated sludge
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: HERDC Pre-Audit
Advanced Water Management Centre Publications
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Created: Wed, 14 Feb 2018, 11:09:42 EST