EFFECT OF EFFECTIVE MICROORGANISMS ON PHYSICAL AND CHEMICAL AQUATIC PARAMETERS Erika Mészáros*, Béla Urbányi, Zoltán Kulik, Gábor Bobák, Árpád Hegyi Department of Aquaculture, Institute of Environmental and Landscape Management, Faculty of Agricultural and Environmental Sciences Szent István University Páter Károly u. 1. H-2100 Gödöllő (Hungary) *Meszaros.Erika@mkk.szie.hu Effective Microorganisms (EM) is a microorganism mixture which contains more than 80 different species. It was invented by the Japanese professor Teruo Higa, in the 1980’s. It was originally developed to improve the quality of soils, but it can be used successfully for other purposes as well, for example in plant production, animal husbandry, environment protection. Our goal was to decrease the thickness of the sludge at the bottom of fish ponds. We wanted to know what kind of other changes occurred at the same time. The EM was applied in a fishing pond, its area was 90 000 m2, the average depth was 1.3 m. The EM was administered into the pond water every month in 100 L volume. There was another pond next to the treated one, which served as a control pond, its area was 50 000 m2. Location of the treated and control pond Administration of EM
We took samples every week at the same day and the same time from both ponds. Samples were transported to the laboratory and were measured immediately. Several parameters were examined. Physical parameters were: turbidity, conductivity and temperature. Chemical parameters were: nitriteion, ammonium-ion, nitrate-ion, ammonia, total nitrogen, pH, total and free chlorine, BOD, TOC, COD and ortophospate, oxygen concentration. I would like to demonstrate only those results, where we found important changes. The most important change was in the pH values. The pH reached significantly lower levels during the whole season (from April to October) in the treated pond compared to the control pond (1. figure). It is essential because the ammonium-ion transforms to ammonia if pH is higher than 8.4. Ammonia is toxic to all living creatures in the water, because this compound can pass freely through the cell membrane, in contrast to the ammoniumion, which can be taken up only by active transport. The ammonia concentration was significantly higher in the control pond, where this parameter was out of the required range during the whole season compared to the treated pond (2. figure). Treated Control
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2. figure: Ammonia concentrations
1. figure: pH values in the ponds and the limit
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3. figure: Orthophosphate-ion concentrations
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There was significantly higher level of orthophosphate-ion in the treated pond (3. figure), and the COD value was significantly higher in the control pond (4. figure) due to the higher organic matter content.
4. figure: Chemical Oxygen Demand
In conclusion the experiment with the EM was successful, it caused reduction in the thickness of the mud. The soft mud thickness was 9,3 cm less in the treated pond after two years which means 8100 m3 less soft mud in the pond. In the control pond there was 6,1 cm rise in sludge, which means 3050 m3 more sludge in the pond after two years. In addition, EM could improve the chemical and physical parameters of pond water. Better water quality was attained in addition to the decreased amount of slugde. As a result aquatic animals have larger, cleaner and healthier living space.