Nitrate removal from drinking water using anoxic packed reactor

Abstract EN

An anoxic upflow packed-bed reactor was operated to denitrify water having a nitrate-nitrogen concentration of 120 mg / 1.

A methanol to nitrate ratio of 0.55, i.e., less than the stoichiometric requirements was utilized throughout the present investigation.

The effects of hydraulic retention time, oxygen tension, and nutrient concentrations on the performance of the process were investigated.

The minimum hydraulic retention time needed to meet the nitrate standard in drinking water was 6 hours.

A higher hydraulic retention time of 12 hours was needed to meet the nitrate standard of 1 mg/l as nitrogen.

No detectable methanol concentration was found in the effluent of the reactor when the system was operated at a hydraulic retention greater than or equal to 9 hours.

The results of the study indicated that once denitrification was established, the dissolved oxygen concentrations in the feed water did not affect the performance of the process and effective denitrification occurred at a dissolved oxygen concentration as high as 8 mg/l.

Thus, oxygen tension was not found critical for the process.

The phosphorus concentration in the feed did not significantly affect the efficiency of the system.

High denitrification efficiencies were achieved at phosphorus concentrations in the feed as low as 0.05 mg/l.

Based on the findings of this research and other evidence, a biochemical model for the denitrification process is proposed.