Enhancing sludge biodegradability through free nitrous acid pre-treatment at low exposure time

Zahedi, S., Icaran, P., Yuan, Z. and Pijuan, M. (2017) Enhancing sludge biodegradability through free nitrous acid pre-treatment at low exposure time. Chemical Engineering Journal, 321 139-145. doi:10.1016/j.cej.2017.03.120

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Author Zahedi, S.
Icaran, P.
Yuan, Z.
Pijuan, M.
Title Enhancing sludge biodegradability through free nitrous acid pre-treatment at low exposure time
Journal name Chemical Engineering Journal   Check publisher's open access policy
ISSN 1385-8947
1873-3212
Publication date 2017-08-01
Sub-type Article (original research)
DOI 10.1016/j.cej.2017.03.120
Open Access Status File (Author Post-print)
Volume 321
Start page 139
End page 145
Total pages 7
Place of publication Amsterdam, Netherlands
Publisher Elsevier BV
Language eng
Subject 1600 Chemistry
2304 Environmental Chemistry
1500 Chemical Engineering
2209 Industrial and Manufacturing Engineering
Abstract The effectiveness of low free nitrous acid (FNA) pre-treatment times (PTs) (<8 h) on waste activated sludge (WAS) is not known. This study explores the effectiveness of four different FNA concentrations (0, 2.49, 3.55 and 4.62 mg N-HNO/L) and three low PTs (2, 5 and 8 h) on WAS characteristics and methane generation. Increasing FNA concentrations and PTs resulted in an increase in the solubility of the organic matter (chemical oxygen demand, proteins and polysaccharides). Cell viability was below 15% in all cases at PTs higher than 2 h. Biochemical methane production tests (BMP) showed a significant increase (20–27%) on specific and total methane production (SMP and MP) when the sludge was pretreated with 2.49- and 3.55 mg N-HNO/L during 5 h and 8 h. Increasing PT (>5 h) resulted in a decrease in MP due to a volatile solid reduction on WAS during the pretreatment. The highest FNA concentration tested (4.62 mg N-HNO/L) did not further improve MP and SMP. This study clearly shows the effectiveness of the FNA sludge pretreatment at low exposure times.
Formatted abstract
The effectiveness of low free nitrous acid (FNA) pre-treatment times (PTs) (<8 h) on waste activated sludge (WAS) is not known. This study explores the effectiveness of four different FNA concentrations (0, 2.49, 3.55 and 4.62 mg N-HNO2/L) and three low PTs (2, 5 and 8 h) on WAS characteristics and methane generation. Increasing FNA concentrations and PTs resulted in an increase in the solubility of the organic matter (chemical oxygen demand, proteins and polysaccharides). Cell viability was below 15% in all cases at PTs higher than 2 h. Biochemical methane production tests (BMP) showed a significant increase (20–27%) on specific and total methane production (SMP and MP) when the sludge was pretreated with 2.49- and 3.55 mg N-HNO2/L during 5 h and 8 h. Increasing PT (>5 h) resulted in a decrease in MP due to a volatile solid reduction on WAS during the pretreatment. The highest FNA concentration tested (4.62 mg N-HNO2/L) did not further improve MP and SMP. This study clearly shows the effectiveness of the FNA sludge pretreatment at low exposure times.
Keyword Anaerobic digestion
Free-nitrous acid pre-treatment
Methane production
Secondary sludge biodegradability
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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