ReNOx - Utilizing residues from biogas plants for a good cause

The main goal of the project is to explore the potential synergies between industrial biogas and cement production. An efficient plant network such as this would close material and energy cycles and, unlike mainstream processes, enable cheaper biogas production. It could also make biogas production independent of state funding.

In Austria, approximately 70 percent of cement production is already fueled by secondary energy resources such as plastic waste, biogenic substitute fuels, old tires, or solvents. Biogas produced from organic waste material would lend itself as a new, CO2-neutral fuel.

An alternative method for recycling of digestate

The ReNOx project is investigating possibilities to network biogas and cement plants at the same site based on a feasibility study. At the same time, it aims to develop a novel processing technique to recycle ammonia from biogas digestate and residues from municipal wastewater treatment plants.

This treatment system, called “Ion-exchanger loop stripping”, is used to recapture surplus ammonia from digestate and sludge liquor for industrial NOx-removal from flue gas. At the same time, clean water is produced that can, in turn, be re-used in the biogas plant without ammonia inhibition or nitrogen reversal. Obtaining a product (an agent to remove NOx) from organic residues is an innovative approach indeed. Operators of biogas and wastewater treatment plants could stand to benefit from a marketable product (denitrification agent) by recycling their own digested sludge.

This alternative way of recycling ammonia from digestates in a non-agricultural context would, in addition, avoid the necessity of storing huge quantities of the material over the winter months. Agriculture, in turn, is often characterized by over fertilization, ammonia and greenhouse gas emissions, and subsequently, groundwater contaminated with nitrates as a result of spreading digested sludge over the fields.

Now, with the possibility of industrially utilizing surplus ammonia the whole year round, agricultural materials flows could be combined with those of industry to mutual advantage.

Consortium Manager

Montanuniversitaet Leoben - Chair of Process Technology and Industrial Environmental Protection

Other Consortium Partners

• Lafarge Zementwerke GmbH
• Christof International Management GmbH
• Lithos Industrial Minerals GmbH
• Sanitary district Knittelfeld and environs
• University of Natural Resources and Life Sciences Vienna - Institute of Environmental Biotechnology
• Energy Institute, Johannes Kepler University Linz

Project Coordinator

Markus Ellersdorfer
E-mail: markus.ellersdorfer@unileoben.ac.at