Continuous process monitoring for biogas plants using microwave sensors

The efficiency of biogas production during anaerobic digestion depends heavily on optimal dosing ratios and stable operations which can not be achieved without accurate and reliable monitoring and control of the dry matter (DM) and organic dry matter (oDM) content. The materials in biogas processes to be measured are either stored in a vessel flowing in a pipe, either as a liquid or as solid particles in pneumatic or liquid assisted transportation with a wide area of the content of DM (1% <; DM > 90). In such cases microwave sensors provide an attractive solution, because microwaves penetrate most materials allowing the non destructive measurement to be representative for a special volume or the cross section of the pipe. The setup of the measuring system for materials with high water content and first results are presented.