Anaerobic Granular Sludge Bed Technology Pages
(home)

(links)

(discovery)

(science)

(technology)

(sustainability)

(forum)

 

Methanogenic Inhibitors

 

Compound
Category

Anaerobic
Toxicity

Comments

Polysaccharides &
Simple sugars

─

    

Proteins &
Aminoacids

─

    

Fats &
Long chain fatty acids (LCFA)

+

 IC50 for LCFA = 500-1.250 mg/l

Simple alcohols

─

   
Volatile fatty acids (VFA)

+
Non-toxic at pH 7.0-8.0
Toxicity is pH-dependent
Non-ionized form is toxic (free VFA)
Acetate and propionate:
(IC50 = 6-16 mg free VFA/l)
Cyanide (CN-)

+++
IC50=  1 mg/l (unadapted sludge)
IC50= 25 mg/l (adapted sludge)
Formaldehyde

+++
IC50= 100 mg/l (unadapted sludge)
IC50= 400 mg/l (adapted sludge)

Inorganic S compounds
  • Sulfide

++

 Toxicity is pH-dependent
Non-ionized form is toxic (free H2S)
IC50 = 250 mg free S-H2S//l
  • Sulfate
 ─ Only at the very high concentrations
IC50 = 3.300 mg S-SO4-2/l
  • Sulfite
 +++ IC50 = 50 mg S-SO3-2/l
Ammonia

++
Toxicity is pH-dependent
Non-ionized form is toxic (free NH3)
IC50 = 50 mg free N-NH3/l
Heavy metals

+++/++
Some heavy metals are very toxic
Soluble form is toxic. Some metal are very toxic (eg. IC 50= 10-75 mg soluble Cu+2/l)

In anaerobic systems, heavy metals are often detoxified by precipitation with carbonates and sulfides.
Salts
 (eg. Na+, K+, Ca2+)

+
Only at high concentrations
IC50 = 4.700-7.600 mg/l

Aromatic compounds
  • Aromatic hydrocarbons

+

 eg. IC50 benzene =        1970 mg/l
     IC50 ethylbenzene =  340 mg/l
  • Phenol

+

 IC50= 1300 mg/l
  • Benzoic acid
 ─ IC50>> 4.250 mg/l
  • Benzaldehyde

+

   
  • Chlorinated phenols
 +++ IC50 pentachlorophenol = 1 mg/l
  • Chlorobenzenes

+++

   
  • Nitro-aromatic compounds

+

 eg. IC50 nitrobenzene = 10 mg/l
  • Aromatic amines

++

 eg. IC50 aniline = 900 mg/l

Aliphatic compounds
  • Chlorinated aliphatic hydrocarbons

+++

 eg. chloroform
IC50= 0.5 mg/l (unadapted sludge)
IC50= 45 mg/l (adapted sludge)

Surfactants
  • Cationic and anionic detergents

++

   IC50 = 20-50 mg/l

Azo dyes

─/+

  Highly variable

Phytochemicals
  • Lignin

─

 High molecular lignin is non-toxic
  • Lignin monomeric compounds

+/++

 eg. IC50 guaiacol =   2.200 mg/l
     IC50 isoeugenol =   264 mg/l
  • Volatile terpenes
 +++ eg. IC50 pinene = 180 mg/l
  • Wood resin
 +++ eg. IC50 abietane = 140 mg/l
  • Tannins
 ++ eg. IC50 bark tannins = 350 mg/l
High molecular weight tannins are non-toxic