Determination of the suitable inoculum for the acclimation of anammox bacteria

Strict wastewater discharge standards are applied in order to reduce the environmental effects of the nitrogen. The biotransformation of the nitrogen has become more economical and efficient with the discovery of new technologies applied by shortening the conventional nitrification-denitrification process pathway. The Anammox (anaerobic ammonium oxidation) process is most preferred nitrogen removal process because of its benefits in terms of reduction in aeration and carbon source costs. The main disadvantage of the process for practical application is the requirement of long acclimation periods due to the low growth rate of Anammox bacteria. For this reason, the selection of the most suitable inoculum is crucial in the startup of the process. In this context, the aim of this study is to determine the appropriate inoculum and the feeding time for the acclimation of the anammox bacteria. For this purpose, two types of inoculum were used, namely inoculum formed by aerobic and anaerobic sludge mixture and inoculum obtained from the solid waste landfill site. The most suitable inoculum was investigated for the acclimatization of anammox bacteria by applying different feeding conditions to these two inoculum. Because very slow growth rates of anammox bacteria, very long processes are required for the acclimation period. Therefore, instead of applying the long acclimation periods during acclimation studies, the suitability of the inoculum and feeding conditions for acclimation of anammox bacteria were determined in a short time by analyzing the relative amount of hydrazine synthase gene, which is specific to anammox bacteria. The results of experimental studies were revealed that anammox bacteria can be acclimated by applying at least 2 hours of feeding period when aerobic and anaerobic sludges are used as inoculum.