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Published on: October 15, 2015
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Activity of preserved anaerobic sludge
Anna Doloman1, Ronald C Sims1, Charles D Miller1
1Department of Biological Engineering, Utah State University, Logan, Utah, USA.
Summary
Preserving mesophilic anaerobic sludge (MAS) using different methods showed varied effects on sludge activity. Freeze-drying offered comparable biogas production to other methods, despite a longer reactivation period for MAS.
Area of Science:
- Environmental Science
- Microbiology
- Biotechnology
Background:
- Anaerobic sludge is crucial for wastewater treatment and biogas production.
- Prolonged storage of anaerobic sludge can impact its microbial activity and performance.
- Understanding optimal preservation methods is essential for maintaining sludge viability.
Purpose of the Study:
- To evaluate the impact of different preservation conditions on mesophilic anaerobic sludge (MAS) activity.
- To compare the effectiveness of four storage methods over 12 months.
- To investigate the influence of sludge source (upper vs. bottom port) on preservation outcomes.
Main Methods:
- Four preservation methods were tested: 23°C, 4°C, -20°C, and freeze-drying.
- Sludge samples were collected from upper and bottom ports of an upflow anaerobic sludge blanket (UASB) reactor.
- Specific methanogenic activity (SMA) tests were conducted after 2.5, 6, and 12 months of storage.
Main Results:
- Bottom port sludge showed a significant decrease in SMA post-storage, unlike upper port sludge, irrespective of preservation method.
- Freeze-dried sludge exhibited similar biogas production to other methods but required a longer reactivation period.
- Differences in susceptibility were attributed to varying methanogenic microorganism content between sludge ports.
Conclusions:
- Preservation method significantly impacts anaerobic sludge activity, with bottom port sludge being more susceptible to degradation.
- Freeze-drying is a viable preservation option for anaerobic sludge, offering comparable biogas yields.
- Sludge sampling location within the UASB reactor influences its stability during anaerobic sludge preservation.
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