Inhibition on anaerobic digestion
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Transcript of Inhibition on anaerobic digestion
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Refferences :
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Oxygen
Sulfur Compounds
Organic Acids (Fatty Acids & Amino Acids)
Nitrate (NO3-)
Ammonium (NH4+) and
Ammonia (NH3)
Heavy Metals
Other InhibitingThresholds
Inhibition Compounds on Anaerobic digestion
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1. Oxygen
• The exclusion of oxygen is not absolutely necessary for acidogens
• Avoiding the presence of oxygen more than 0.1 mg L − 1 O 2 for methanogens
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2. Sulfur Compounds
• Sulphate ions inhibits to the process by following this reaction:
• Hidrogen sulphide inhibits the metabolic activity of anerobic bacteria.
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• Sulphate is reduced to hydrogen sulfide by sulphate reducing bacteria (SRB)
• Hydrogen sulphide is formed by degradating of organic coumponds.
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Monitoring sulphate/sulphide control:
• Increasing the pH (caustic soda addition)
• Addition precipitation chemicals (iron salt) and Physico-chemical techniques (stripping)
The process are coagulation, oxidation, precipitation (Oude Elferink et al., 1994; Song et al., 2001; Chen et al., 2008).
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3. Organic Acids (Fatty Acids and Amino Acids
• Long chain fatty acids (LCFA’s) inhibit on methanogens.
Propionic acids performs most inhibitor (Dublein and Steinhauser, 2008)Lauric acids performs most inhibitor (Gerardi, 2003)
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Volatile acids such as acetate, butyrate, and propionate causes a decreasing pH.
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Nitrate (NO3- )
• The redox potential occure more negative• Gas quality have high portion of nitrogen
content
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Ammonium (NH4+)
and Ammonia (NH3)
Nitrogen source-providing buffering capacity-
(Dublein and Steinhauser, 2008)
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(Gerardi, 2003)
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Controling the ammonia content• ANAStrip-process
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Heavy Metals
• They are stimulator the activity of bacteria• But in higher concentration can be toxic• This groups incudes lead, mercury, cadmiun,
uranium, iron, zinc, copper, chromium, manganese, molybdenum, nickle, and selenium.
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Other inhibiting thresholds
• Disenfectans• Chlorinated hydrocarbons• Benzene ring compounds• Cyanide• Recalcitrant (flavour compounds, essential oil)