This paper presents the effects of an application of Effective Microorganisms (EM) technology in line with the method developed by Sitarek, thus evaluating its effectiveness as a tool in the biological restoration of a water body. In 2012-2013, EM was applied in Muchawka Reservoir situated in the town of Siedlce (eastern Poland). Analyses of water parameters and bottom sediments were carried out in 2011, before the EM technology was implemented and again in 2013-2015 after the EM application was completed. In spring 2011, the average total nitrogen (TN) content at the surface was 3.1 mg dm-3 while the total mineral nitrogen content equalled 0.893 mg dm-3. After the EM application was completed, in the summer of 2013, the TN content was on average 2.5 mg dm-3. The content of nitrates and nitrites in the summer of 2013 reached 1.20 mg dm-3 at the most. Lower levels of such forms of nitrogen were observed in 2013 and also in subsequent years at the bathing beach (site 1) and the hostel (site 3) than at the inflow (site 4). Likewise, the highest content of phosphates was recorded at the inflow site (4), being four-fold lower at the other sites (1, 3). The average content of TP before the EM technology was applied was 0.205 mg dm-3, whereas after the application of effective microorganisms it fell down to 0.189 mg dm-3 (2013-2015). Only slight changes of TSITP indicated that waters in Muchawka Reservoir were eutrophic. After EM was applied twice, no streaks, cyanobacterial scums or pollution at the bathing sites were visible. The bacteriological evaluation of the water samples was carried out by the County Branch of the State Sanitary Inspectorate in Siedlce. The bacteriological water quality was described as “excellent”. These findings suggest that the method developed by Sitarek, combined with probiotic preparations, could be a useful tool in the restoration of water bodies, but the conclusion requires further detailed verification.

22.2.2017