Peat production and utilization for horticultural and chemical purposes in Finland

In Finland, approximately one million cubic meters of peat is utilized annually for non-energy purposes. At the moment the main forms of peat use are horticultural and growing purposes. Nearly one half of production has been exported. The utilization of peat for environmental purposes is increasing, and the production of biological active compounds and mixtures also seems to be attractive. Before reaching the actual fuel peat layer a great deal of light, weakly decomposed surface peat has to be removed or produced. This material may be refined for soil improvement and sorbent purposes, litter, and compost. Horticultural peat production technology has not developed in Finland as intensively as that for fuel peat, but there have been many technical and methodological solutions, which have been also directly applicable to horticultural peat and to peat production in general. The machinery used in peat production and in agriculture has become more suitable for horticultural peat. Horticultural peat bogs have in general been ditched in the same way as in fuel peat production. It often takes nearly twice as long to dewater the Sphagnum peat moss as it does a corresponding fuel peat bog. The aim of effective drainage used in Finland is to reach full and effective production capacity as soon as possible and also to reduce maintenance. Horticultural peat of good quality has large particle size. The peat layer is primarily cut with rotating drum millers, while (rotating) farm harrows are also used. In Finland horticultural peat is not produced using the sod peat method. The turning of milled peat usually takes place with spoon harrows and peat is harvested using the Haku method, and with vacuum and mechanical harvesters. Peat is stored in field stockpiles. Horticultural peat is mostly delivered in plastic bags made by rotating chamber presses. Other horticultural peat products include peat sheets, boards, pellets and pots made from air and artificially dried peat. Quality control is of great importance in production. At the moment peat is used in environmental technology for sludge treatment and dewatering (filtering), as litter and sorbent for oil, liquid and odorous compounds. Production takes place alongside with fuel peat. The full-scale chemical processing of peat has not been successful up until now. Peat coke and synthetic gas have been made on an industrial scale in Finland. Research and bench-scale development have been carried out since the 1940`s by VTT and several universities. The thermochemical processes were studied extensively up to the end of last decade. At the moment interest is focussed on the utilization of separate fractions and compounds found in peat and on biochemical and biological conversion processes. Two process alternatives have been studied in Finland within the research programme on the artificial dewatering of peat (ADEWA): the production of milled peat of high water content using surface cutting technique, and the slurry method. The wet peat will be used in high efficiency electricity production. In connection with this the production of chemicals such as humic substances might also be economically viable. The chemical mapping of peatlands has been carried out for fuel peat production, chemical refining, and the estimation of the environmental impacts of peat production.