ADAPTATION OF METHANOGENIC SLUDGE TO HIGH AMMONIA-NITROGEN CONCENTRATIONS

The influence of ammonia-nitrogen concentrations in excess of 1500 mg 1-1 on the methane formation from volatile fatty acids by two types of methanogenic sludge was investigated in batch experiments. One was digested sewage sludge, acclimated to 815 mg 1-1 ammonia-nitrogen and the other was digested piggery manure, acclimated to an ammonia-nitrogen concentration of 2420 mg 1-1. In the experiment with digested sewage sludge, methane formation took place still at an ammonia-nitrogen concentration as high as 5 g 1-1. However, an increasing lag-phase was observed at increasing ammonia-nitrogen concentrations in the range 730-4990 mg 1-1. On the other hand in digested piggery manure methane formation immediately started without any lag-phase in the ammonia-nitrogen concentration range of 605-3075 mg 1-1. In the experiments with both types of sludge the maximum methane formation rate slowly decreased with increasing ammonia-nitrogen concentrations. © 1979.