Optimum growth requirements of nitrifying consortia developed from treated sewage

Abstract

The optimum growth requirements of two nitrifying consortia developed from treated sewage by enrichment technique were determined by a series of experiments. There was total inhibition of nitrification at above 2.75 g l^-1 NH₄⁺- N and 2.5g l^-1 NO₂^- - N and the ammonia oxidizing consortium preferred a <i>p</i>H<i> </i>at 8.5 and the nitrite oxidizing consortium a <i>p</i>H of 7.5 as the optima for nitrification. Optimum temperatures were between 20° and 30°C for both the groups. As the rate of airflow was increased from 1 to 7 l/min, the build-up of NO₂^--N increased 10-fold and the consumption of NO₂^- -N increased by a factor of 28.8 implying that the ammonia oxidizing consortium in a bioreactor required three times more aeration than that for nitrite oxidizers for ex pressing their full nitrifying potential. These data directly contribute for developing a fermentation process for the mass production of nitrifiers as well as for designing bio reactors for nitrifying sewage.