The main goal of optimising anaerobic digestion processes is to maximise the yield of CH4 and minimise the formation of H2S. Researchers at the University of Kaiserslautern have noticed that calcium nitrate - Ca(NO3)2 - can help achieve this goal by exerting a positive impact on the community of micro-organisms. Based on these findings, Yara International has patented a solution that has the ability to accelerate and optimise the conversion of substrates into biogas.