Bio-refinery Pyrolysis Waste Water to Become Useful
Carbonization processes such as pyrolysis and hydrothermal carbonization (HTC) expected to fulfil important roles in future bio-refinery concepts. However, until now a major problem is: These processes form waste waters that contain various environmental hazardous substances. Researchers in Potsdam/Germany seem to crack it.
Potsdam/Germany – The production of materials and chemicals from renewable resources usually bases on biological or thermochemical processes. The latter possess the advantage of very high reaction rates. At temperatures of 250°C and above, even complex organic compounds that are recalcitrant to biologic degradation like lignin are rapidly decomposed.
However, thermochemical processes are highly unselective in their product pattern. Besides the target products a range of more or less problematic organic compounds is formed. This decreases the product yield and causes additional costs for the waste water treatment.
Biochar and Syngas
Researchers of ATB’s (Leibniz Institute for Agricultural Engineering) junior research group APECS in Potsdam/Germany have put focus on the liquid by-products of thermochemical biomass conversion. This includes waste waters from HTC as well as pyrolysis.
The main product of pyrolysis and HTC is biochar, a carbon and energy-rich solid material, which can be used as fuel, but also for a range of further applications from soil amendment to carbon electronics. By-products of pyrolysis are the so-called syngas, which can be used as a fuel, and a condensate composed of volatile compounds, for which no satisfying type of use exists today.
In the HTC, a process liquid is formed which contains a wide variety of organic and mineral compounds. Thus, both waste waters from HTC and pyrolysis require an effective treatment before they can be released into the environment. In their latest article published in the scientific journal “Bioresource Technology”, the Potsdam researchers report on the successful anaerobic biological conversion of water-soluble pyrolysis condensates in laboratory tests.