How does nitrification take place in an activated sludge system?
It is important to note that it is the ammonium ion (NH4+) and not ammonia (NH3) that is oxidized during nitrification. When proteins and organic nitrogen compounds, e.g. urea (NH2CONH2), are hydrolysed and degraded amino acids are released. (An amino acid is an organic nitrogen compound that contains the carboxylic group (-COOH) and the amino group (-NH2)). The amino group is removed by bacterial activity this is known as de-amination – and is quickly converted to the ammonium ion, e.g. Citrobacter removes the amino group from the amino acid glycine. Nitrification is a bio-chemical reaction that occurs inside bacteria. Two species of bacteria are involved in the process – Nitrosomonas and Nitrobacter. These bacteria are collectively known as nitrifiers and are autotrophic, i.e. they get their carbon source from inorganic carbon (carbonates, bicarbonates) or carbon dioxide. (The bacteria responsible for breaking down carbonaceous BOD in an activated sludge system are known as organotro
