Dear all, I'm a university student in charge of developing a biochemical device (reactor) for the depuration of leather factory wastewaters, this is an european project leaded by Ambiental Engineering University of Florence. Part of this device should be colonized with fungi in order to purify water, and they (the fungi) need a biodegradable material (cellulose, starch) with a certain porosity to grow, but it also has to be non-soluble in water. The material should also be cheap and easy to find. Until now I've looked at some biodegradable polymers such as PLA, PCL, some fibers (bagasse, hemp) and even foams (starch foam pellets are produced as insulating materials), wich seemed to be the best choice... too bad they're water soluble. What do you think? Is there any material or composite or something else you're thinking about?