Use of municipal waste products in energy forestry: highlights from 15 years of experience

Pre-treated wastewater, sewage sludge and methanogenic landfill leachate were applied to short rotation energy forestry, i.e. Salix (willow) plantations. The nutrient content in wastewater was well balanced with the nutrient uptake in Salix stems. With sludge and leachate used as the main fertilizer resource, potassium and phosphorus fertilizers, respectively, must be added for sustainable biomass production. In most cases the growth was increased after application of the waste products. Production rates at same or higher levels as conventionally-fertilized willow plantations were recorded. Water is pointed out as the single most important growth factor. Waste management according to presented concepts could offer good treatment performance without adverse effects on soil, groundwater or vegetation. During the course of the field tests full-scale applications have been established.