Humic acid inhibition of hydrolysis and methanogenesis with different anaerobic inocula
There is increasing evidence that humic acid (HA) is hampering the performance of anaerobic digesters treating animal manures and thermally-hydrolysed waste activated sludge. In the present study, HA inhibition and inhibition resilience was examined for hydrolysis (carbohydrate and protein) and acet...
| Main Authors: | , , , , , , |
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| Other Authors: | |
| Format: | Journal Article |
| Language: | English |
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2020
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| Online Access: | https://hdl.handle.net/10356/138558 |
| _version_ | 1826126090868883456 |
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| author | Yap, Shao Dong Astals, Sergi Lu, Yang Peces, Miriam Jensen, Paul D. Batstone, Damien J. Tait, Stephan |
| author2 | School of Materials Science & Engineering |
| author_facet | School of Materials Science & Engineering Yap, Shao Dong Astals, Sergi Lu, Yang Peces, Miriam Jensen, Paul D. Batstone, Damien J. Tait, Stephan |
| author_sort | Yap, Shao Dong |
| collection | NTU |
| description | There is increasing evidence that humic acid (HA) is hampering the performance of anaerobic digesters treating animal manures and thermally-hydrolysed waste activated sludge. In the present study, HA inhibition and inhibition resilience was examined for hydrolysis (carbohydrate and protein) and acetotrophic methanogenesis with four distinct full-scale anaerobic inocula. The aim was to further understand HA inhibition and to explore potential relationships between microbial factors and inhibition resilience. For two of the four tested inocula, cellulose degradation showed a start-up delay that lengthened as HA concentration increased from 0 to 2 g L-1. This inhibition was reversible because, after the initial delay, subsequent hydrolysis rates and methane yields were not significantly influenced by HA concentration. Cellulose hydrolysis results at HA concentrations below 2 g L-1 support a threshold inhibition mechanism, i.e. HA complexes with hydrolytic enzymes preventing them from binding with cellulose, but once all the HA had been complexed, enzymes subsequently released are free to bind with cellulose. Inocula with higher cellulose hydrolytic activity were less affected by HA inhibition, suggesting a potential link between HA inhibition resilience and microbial activity. However, above 5 gHA L-1, cellulose hydrolysis rates decreased with increasing HA concentration; indicating that the mechanisms of inhibition may change depending on some threshold HA concentration. Protein hydrolysis and acetotrophic methanogenesis were less susceptible to HA inhibition than cellulose hydrolysis, since signs of inhibition were only observed above 5 gHA L-1. Acetotrophic methanogenesis was partially inhibited at 10 gHA L-1 and completely inhibited at 20 gHA L-1. These results further support that HA inhibition is selective towards particular enzymes. |
| first_indexed | 2024-10-01T06:47:03Z |
| format | Journal Article |
| id | ntu-10356/138558 |
| institution | Nanyang Technological University |
| language | English |
| last_indexed | 2024-10-01T06:47:03Z |
| publishDate | 2020 |
| record_format | dspace |
| spelling | ntu-10356/1385582020-06-01T10:13:43Z Humic acid inhibition of hydrolysis and methanogenesis with different anaerobic inocula Yap, Shao Dong Astals, Sergi Lu, Yang Peces, Miriam Jensen, Paul D. Batstone, Damien J. Tait, Stephan School of Materials Science & Engineering Singapore Centre for Environmental Life Sciences and Engineering Engineering::Environmental engineering Anaerobic Digestion Humic Acid There is increasing evidence that humic acid (HA) is hampering the performance of anaerobic digesters treating animal manures and thermally-hydrolysed waste activated sludge. In the present study, HA inhibition and inhibition resilience was examined for hydrolysis (carbohydrate and protein) and acetotrophic methanogenesis with four distinct full-scale anaerobic inocula. The aim was to further understand HA inhibition and to explore potential relationships between microbial factors and inhibition resilience. For two of the four tested inocula, cellulose degradation showed a start-up delay that lengthened as HA concentration increased from 0 to 2 g L-1. This inhibition was reversible because, after the initial delay, subsequent hydrolysis rates and methane yields were not significantly influenced by HA concentration. Cellulose hydrolysis results at HA concentrations below 2 g L-1 support a threshold inhibition mechanism, i.e. HA complexes with hydrolytic enzymes preventing them from binding with cellulose, but once all the HA had been complexed, enzymes subsequently released are free to bind with cellulose. Inocula with higher cellulose hydrolytic activity were less affected by HA inhibition, suggesting a potential link between HA inhibition resilience and microbial activity. However, above 5 gHA L-1, cellulose hydrolysis rates decreased with increasing HA concentration; indicating that the mechanisms of inhibition may change depending on some threshold HA concentration. Protein hydrolysis and acetotrophic methanogenesis were less susceptible to HA inhibition than cellulose hydrolysis, since signs of inhibition were only observed above 5 gHA L-1. Acetotrophic methanogenesis was partially inhibited at 10 gHA L-1 and completely inhibited at 20 gHA L-1. These results further support that HA inhibition is selective towards particular enzymes. 2020-05-08T04:37:49Z 2020-05-08T04:37:49Z 2018 Journal Article Yap, S. D., Astals, S., Lu, Y., Peces, M., Jensen, P. D., Batstone, D. J., & Tait, S. (2018). Humic acid inhibition of hydrolysis and methanogenesis with different anaerobic inocula. Waste Management, 80, 130-136. doi:10.1016/j.wasman.2018.09.001 0956-053X https://hdl.handle.net/10356/138558 10.1016/j.wasman.2018.09.001 30454992 2-s2.0-85053053087 80 130 136 en Waste Management © 2018 Elsevier Ltd. All rights reserved. |
| spellingShingle | Engineering::Environmental engineering Anaerobic Digestion Humic Acid Yap, Shao Dong Astals, Sergi Lu, Yang Peces, Miriam Jensen, Paul D. Batstone, Damien J. Tait, Stephan Humic acid inhibition of hydrolysis and methanogenesis with different anaerobic inocula |
| title | Humic acid inhibition of hydrolysis and methanogenesis with different anaerobic inocula |
| title_full | Humic acid inhibition of hydrolysis and methanogenesis with different anaerobic inocula |
| title_fullStr | Humic acid inhibition of hydrolysis and methanogenesis with different anaerobic inocula |
| title_full_unstemmed | Humic acid inhibition of hydrolysis and methanogenesis with different anaerobic inocula |
| title_short | Humic acid inhibition of hydrolysis and methanogenesis with different anaerobic inocula |
| title_sort | humic acid inhibition of hydrolysis and methanogenesis with different anaerobic inocula |
| topic | Engineering::Environmental engineering Anaerobic Digestion Humic Acid |
| url | https://hdl.handle.net/10356/138558 |
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