Iron and biogas synergy improves digestionEffect of zero-valent iron (ZVI) and biogas slurry reflux on methane production by anaerobic digestion of waste activated sludge.
We explored how the addition of zero-valent iron (ZVI) and the refluxing of biogas slurry can enhance the efficiency of anaerobic digestion. The research made it clear that the best methane production occurred when the biogas slurry reflux was set at a 60% ratio.
Interestingly, while ZVI didn't enhance its own bioavailability in the anaerobic digestion process, it worked well in combination with the biogas slurry. We observed that this combination notably increased the presence of key microorganisms that play a significant role in the process of direct interspecific electron transfer, which is crucial for methane production.
The dominant bacteria in this mix included Methanosaeta, Methanobacterium, Methanobrevibacter, and Methanolinea, making up more than 60% of the total methanogenic population. By promoting hydrogen production due to the corrosion of ZVI, we found that biogas slurry reflux provided necessary conditions for thriving anaerobic microorganisms.
This cooperative effect not only advanced the growth of hydrogen-producing methanogens but also boosted the functioning of vital enzymes involved in the breakdown and conversion of waste materials, thus enhancing the entire anaerobic digestion system. Ultimately, our findings suggest that while ZVI alone didn’t show a strong effect, it plays an important role when paired with biogas slurry reflux in making the anaerobic digestion process more efficient.
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