Nitrate removal from agricultural infiltrate by bioaugmented free and alginate entrapped cells.

A bench-scale sand column experiment was conducted to investigate nitrate removal from synthetic agricultural infiltrate by denitrifying bacterial cells entrapped in calcium alginate compared to free cells. The effects of methanol as a carbon source and cell loading were examined. Low (0 to 50%) nitrate removal was observed in both entrapped and free-cell columns without methanol supplement. In the presence of methanol, nitrate removals of 90 to 99% and 56 to 75% were obtained for entrapped and free-cell columns, respectively. Nitrate removal followed first-order kinetics. The entrapped-cell columns achieved higher nitrate removal than the free-cell columns because of less bacterial losses. Scanning electron microscopic images supported the nitrate removal results that the denitrifying bacteria proliferated in the entrapment matrix, and several nitrogen gas voids were produced from denitrification.