Influence of the physicochemical properties of inorganic supports on the activity of immobilized bacteria for water denitrification

The denitrification of polluted water was studied by using supported E-coli bacteria. The physicochemical characteristics of supports and the influence of these properties on the bacteria performance were analyzed. Inorganic supports oxides and zeolites were selected in order to cover a wide range of porosity and surface chemical properties and the denitrification process systematically studied. Consecutive denitrification cycles in batch experiments and the toxicity of supports were also analyzed. The acidity of supports provokes a slower reduction processes, favoring also a high concentration of intermediate nitrites in solution for longer periods. The NO3− reduction is faster than the NO2− one, being also less influenced by the support characteristics. Anyway, the total denitrification is reached in all cases. The best performance was obtained with bacteria supported on mesoporous and non-acid silica support. [Display omitted] •Denitrification of polluted water was studied using supported bacteria.•Support strongly influences the bacteria performance.•The bacteria activity decreases with increasing support acidity.•Higher concentration of intermediate nitrite is observed using acid supports.•Nitrates are completely reduced to gaseous products.