Environmental aspects of alternative wet technologies for producing energy/fuel from peat. Final report

Abstract

Peat in situ contains up to 90% moisture, with about 50% of this moisture trapped as a colloidal gel. This colloidal moisture cannot be removed by conventional dewatering methods (filter presses, etc.) and must be removed by thermal drying, solvent extraction, or solar drying before the peat can be utilized as a fuel feedstock for direct combustion or gasification. To circumvent the drying problem, alternative technologies such as wet oxidation, wet carbonization, and biogasification are possible for producing energy or enhanced fuel from peat. This report describes these three alternative technologies, calculates material balances for given raw peat feed rates of 1000 tph, and evaluates the environmental consequences of all process effluent discharges. Wastewater discharges represent the most significant effluent due to the relatively large quantities of water removed during processing. Treated process water returned to the harvested bog may force in situ, acidic bog water into recieving streams, disrupting local aquatic ecosystems.