Emissions of peat production into watercourses are decreasing

The emissions of peat production into watercourses are tried to be decreased by chemical addition into drying waters of peat production area. In the chemical adding test, which is a part of the Aqua Peat-95 research program, carried out in Haapasuo peat production area in Leivonmaeki commune, was used techniques commonly used in purification of drinking water. The method is based on precipitation of dissolved substances from mire water using ferric sulphate, and settling of formed precipitate in multi-stage settling pond system. The ferric sulphate decreases the pH of the water by 2.0-2.5 units, so the acidified water is neutralized with sodium hydroxide before leading into watercourses. In Haapavesi the drying water is pumped from the collecting pond, built in main ditch, via chemical adding station into settling pond, from which the water flows into compartment ponds and from there into lake Rutajaervi. The ferric sulphate is added into water in sewage pipe, mounted after the pumping station, there it is mixed well into water coming from the mire due to strong and turbulent flow. The chemical adding test was started in 26th of may. The concentrations of the chemicals were varied during the test in order to find the optimal dosage, the pond volume and the delay of water in the ponds have been increased, the pump power has been adjusted and the mixing of the chemicals have been improved in order to achieve the right efficiency. The price of the chemical adding is not yet available, but the chemical costs in Haapasuo mire in 1992 were about 0.30 FIM/pumped water m3, which equals to about 500 FIM/d. The equipment costs and the utilization and maintenance costs of the equipment must be added into this