Inhibition on anaerobic digestion
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Transcript of Inhibition on anaerobic digestion
Refferences :
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
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
2. Sulfur Compounds
• Sulphate ions inhibits to the process by following this reaction:
• Hidrogen sulphide inhibits the metabolic activity of anerobic bacteria.
• Sulphate is reduced to hydrogen sulfide by sulphate reducing bacteria (SRB)
• Hydrogen sulphide is formed by degradating of organic coumponds.
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).
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)
Volatile acids such as acetate, butyrate, and propionate causes a decreasing pH.
Nitrate (NO3- )
• The redox potential occure more negative• Gas quality have high portion of nitrogen
content
Ammonium (NH4+)
and Ammonia (NH3)
Nitrogen source-providing buffering capacity-
(Dublein and Steinhauser, 2008)
(Gerardi, 2003)
Controling the ammonia content• ANAStrip-process
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.
Other inhibiting thresholds
• Disenfectans• Chlorinated hydrocarbons• Benzene ring compounds• Cyanide• Recalcitrant (flavour compounds, essential oil)