Two phase automatic digestion of solid dairy manure

Summary

Agrifood Research Finland completed a feasibility study concerning on-farm dry fermentation. The study included the documentation of a prototype plant of a dairy farm at Järna about 50 km south of Stockholm. Interesting features of the plant are amongst others the recycling of a second-hand smokestack as reactor material, the inclined first reactor for mixing the solid manure by gravity force, the bottomless drawer technique for discharging, the fixed film technique for rapid methane generation, and a manure compost produced with low nitrogen losses. The recently developed technology is in the process of testing and refinement.
The local association of farms, horticulture enterprises, food processing units, food stores, and consumers in Järna aims to recycle organic waste. The goal is reduced use of non-renewable energy and use of the best-known ecological techniques in each part of the system, to reduce consumption of limited resources and minimize harmful emissions to the atmosphere, soil, and water. The biogas plant served as reference plant for nutrient recycling solutions within the BERAS-project of "The Baltic Sea Region INTERREG III B Neighbourhood Programme 2000-2006" of the European Union. Presently the biogas plant digests dairy cattle manure, organic residues, and food remains originating from the farm and the surrounding food processing units.