Nitrate in drinking water is a hazard to both humans and animals. Contamina
ted water can cause methemoglobinemia and may pose a cancer risk. Permeable
barriers containing innocuous oils, which stimulate denitrification, can r
emove nitrate from flowing groundwater. For this study, a sand tank (1.1 x
2.0 x 0.085 to in size) containing sand was used as a one-dimensional open-
top scale model of an aquifer. A meter-long area near the center of the tan
k contained sand coated with soybean oil. This region served as a permeable
denitrifying barrier. Water containing 20 mg l(-1) nitrate-N was pumped th
rough the barrier at a high flow rate, 11121 week(-1), for 30 weeks. During
the 30-week study, the barrier removed 39% of the total nitrate-N present
in the water. The barrier was most efficient during the first 10 weeks of t
he study when almost all of the nitrate and nitrogen was removed. Efficienc
y declined with time so that by week 30 almost no nitrate was removed by th
e system. Nitrite levels in the effluent water remained low throughout the
study. Barriers could be used to protect groundwater from nitrate contamina
tion or for the in situ treatment of contaminated water. At the low flow ra
tes that exist in most aquifers, such barriers should be effective at remov
ing nitrate from groundwater for a much longer period of time. Published by
Elsevier Science B.V.