The eutrophication of body of waters is a global problem. It is claimed that “Effective microorganisms (EM)” technology enables removal of nutrients from waters by using natural microorganisms. The aim of this work was to clarify how EM mudballs utilizing this particular technology suit for removal of nutrients from natural and wastewaters in Finland.

The function of EM technology and its applications together with the composition of EM mudballs were performed in the theoretical part. The Finnish water systems and the potential usage of EM technology were also familiarized. In the experimental part the change of nutrient contents in six different water samples were followed while using EM mudballs. A part of the samples were kept in the fridge to get closer to the climate conditions in Finland. The analyzed nutrients were nitrate, sulfate, phosphate and nitrogen.

According to the results the usage of EM mudballs mainly removes nitrate from water samples. Instead the removal of sulfate was considerably lower. Except for a few samples the sulfate concentrations didn’t go below the starting level although occasional decrease was observed. Phosphate concentrations were generally very low and they didn’t exceed the detection limit during the experiments. Only the synthetic sample containing phosphate showed decrease in phosphate concentration which however returned close to the original level in the end of experiment. Increased nitrogen concentrations in the samples were caused by ammonium formed as a fermentation product. For this reason also pH increased in the samples.

The experiments confirmed earlier research results which claim that EM mudballs decomposition starts after two weeks from the addition of EM mudballs in the water samples. Unlike in the earlier studies in this experiment the EM mudballs seemed to work better at lower temperature. This experiment indicated that the utilization of EM technology for removal of nitrate from Finnish water systems could be a potential option in the future.