Frank Wuttke

Mechanical and hydraulic behavior of sub-sea sediments is poorly understood, and prediction of sediment destabilization and mechanical failure is linked to extreme uncertainties. This concerns deep-sea technical activities such as drilling, natural gas production or deployment of deep-sea equipment, stimulating intense effort towards developing novel strategies for sub-marine soil or slope stabilization. Inspired by recent success of microbial carbonate precipitation for terrestrial civil and environmental engineering objectives such as soil stabilization or building restoration1,2, it is assumed that biotechnical precipitation of carbonate minerals could also be the remedy for sub-sea sediment stability issues3. Although engineering objectives appear to be similar, technology transfer might be complicated due to vastly different physical, chemical and microbiological conditions in terrestrial and marine environments. Here we propose a combined microbiological-geomechanical approach to elucidate biotechnical potentials of microbial precipitation and mineral formation for sub-sea sediment stabilization. Our key objective is to test and quantify mechanical and hydraulic effects from different microbially precipitated amorphous phases and minerals (Ca.Mg-carbonates, metal sulfides, metal oxides/hydroxides) under in situ conditions in high-pressure flow-through incubation studies using novel and unique triaxial test systems4. This project brings together scientists from marine microbiology and soil mechanics, combining expertise from CAU and GEOMAR workgroups synergistically in collaborative lab experiments, data evaluation and numerical simulation.