Outotec manure, slurry, and sludge processing technology

Abstract

Relevant waste flows like sewage sludge, farmyard manure, digestion residues, and humid residues from food and feed production are known for food safety issues and for environmental and waste management problems. If used as a resource for crop nutrients and soil fertility, distribution is the main issue: urbanization and intensive livestock farming produce mass flows requiring extended cropland typically not available in the densely populated regions of our planet. Thermal conversion is an acknowledged option for concentration and recycling of mineral residues including phosphates, but the typical moisture content of > 70 wt% makes it difficult to yield relevant surplus energy flows. This challenge is approached by increasing the efficiency of drying and replacing combustion by gasification, in essence by making effective use of the hydrogen (H 2 ) molecules of water in the process chain. Outotec's technology approach aims at keeping H 2 molecules in the loop and eventually using them in the form of a hydrogen-rich gas in a variety of energy and biochemical applications. The approach is intrinsically circular, and the related processes - closed-loop steam drying and steam gasification - are well known but have not been applied to the waste flows and in the configuration as outlined in this book. If successfully implemented, waste flows in the order of 1-1.5 billion cubic meters in the EU28 may be recycled to a relevant building block of a future hydrogen economy with a vast array of applications in the energy and biochemistry sector.