| abstract |
To treat eutrophic surface water, with a muddy bottom, water or a water/gas mixture with or without chemical additives is fed to the water above the sediment until the nutrients in the upper level of the sediment form minerals to form a sepg. layer between the water and the lower levels of the sediment mud. Water enriched with oxygen is fed in to pref. nitrify the sediment. After nitrification, eddied sediment is mixed with water low in oxygen to give denitrification, followed by the addition of a precipitation agent. The precipitating agent can be added at the end of nitrification and before denitrification. At the same time as denitrification, an upwards stream of gas/water/plankton mixt. is formed through the action of the fine bubbles and local pressures with a biochemical reaction, for the mixture stream to pass into a degassing stage. The concn. of matter and harmful substances in the water is measured and controlled to eliminate them and, at the same time, the biochemical cleaning stages are ended. The cleaned water, enriched with oxygen, is either returned to the water or recirculated to treat the sediment. ADVANTAGE - The technique prevents the release of nutrients from the sediment mud into the water on contact with it. |