Bacteria enclosure between silica-coated membranes for the degradation of organic compounds in contaminated water

A non-conventional technique is proposed for the enclosure of either pure bacterial cultures or entire biocoenoses, for
a possible utilization in the treatment of contaminated water. Biological components have been enclosed between
polyester membranes coated by silica films consistingof: (a) SiO2 and nitrocellulose, (b) SiO2, ZnS crystals and
nitrocellulose, (c) SiO2, TiO2 crystals and nitrocellulose, (d) SiO2, ZnS and TiO2 crystals and nitrocellulose.
Morphological, structural and mechanical features of membranes were investigated by means of optical and electron
microscopy, mercury porosimetry and wear resistance tests. Degradation kinetics have been finally studied by dipping
the entrapped biomass into aqueous solutions of three different model organic compounds (a-D-glucose, ethyl alcohol
and peptone). Results are very promising: in fact, no metabolic inhibition mechanisms of microorganisms have been
evidenced. The porosity of the system allows mass transfer through the membranes, hence bacteria can grow and
degrade pollutants. Besides, by this system, cells are constrained, avoiding they to spread across the retainment scaffold.