Growth Characteristics and Nitrification Rate of Nitrifying Bacteria Entrapped in Pellets.

To estimate a biological succession of nitrifying bacteria entrapped in PEG gel, growth rate, death rate and nitrifying rate of nitrifying bacteria were investigated under a various phase condition. The immobilized nitrifying bacteria were acclimated for 2 weeks with supply of inorganic synthetic wastewater containing NH4-N of 20mg/l. Specific growth rate of nitrifying bacteria was 0.73 d-1 and nitrifying bacteria increased to 109 MPN/ml-pellet under acclimation term. After acclimation wastewater with NH4-N 20-100mg/l was continuously treated at a loading rate of 0.16-0.80kg-N/m3/d. The NH4-N concentration of the effluent could be reduced to 2mg/l or less and removal ratio was 90%. Number of nitrifying bacteria was oscillated between 107-109MPN/ml-pellet under steady state loading condition. Nitrification rate was increasing with increase in number of nitrifying bacteria. Nitrifying bacteria was decreasing during no loading condition. The specific death rate was 0.14-0.15d-1 and half life time was 4-5d.