Abstract
A pilot-plant study, made to clarify whether biological denitrification is a possible and suitable method for
nitrate reduction of drinking water in Sweden is presented. The concentration of nitrate-nitrogen in un-treated
water was 10–15 mg/l. The reactor was a 1.2 m aluminium tube with a inner diameter of 0.19 m. 0.75 m
was filled with Filtralite®, expanded clay, through which the nitrate-contaminated water was forced to flow
upwards with a velocity of 0.5 m/h. The system was run with artificial nitrate-polluted potable water from the
three pumps during a week. The nitrate was then added to the water by using a solution of sodium nitrate. As
carbon-source, sodium acetate was used. The Hydraulic Retention Time (HRT) of the system was 5.9 h, of
which approximately 2.6 hours were within the bacterial support material. The C:N ratio was found to be below
1.5 and the system was very stable. Since the process will not work as long as oxygen is present, oxygen was
degassed, but the importance of trace oxygen amounts could not be decided, since it wasn’t possible to decrease
the oxygen to really low concentrations in the water prior inlet to the reactor. It was concluded that it is possible
to use biological denitrification for drinking water. Post-treatment in an aerated reactor will be needed to ensure
that no carbon or nitrite-nitrogen comes into the potable water.
nitrate reduction of drinking water in Sweden is presented. The concentration of nitrate-nitrogen in un-treated
water was 10–15 mg/l. The reactor was a 1.2 m aluminium tube with a inner diameter of 0.19 m. 0.75 m
was filled with Filtralite®, expanded clay, through which the nitrate-contaminated water was forced to flow
upwards with a velocity of 0.5 m/h. The system was run with artificial nitrate-polluted potable water from the
three pumps during a week. The nitrate was then added to the water by using a solution of sodium nitrate. As
carbon-source, sodium acetate was used. The Hydraulic Retention Time (HRT) of the system was 5.9 h, of
which approximately 2.6 hours were within the bacterial support material. The C:N ratio was found to be below
1.5 and the system was very stable. Since the process will not work as long as oxygen is present, oxygen was
degassed, but the importance of trace oxygen amounts could not be decided, since it wasn’t possible to decrease
the oxygen to really low concentrations in the water prior inlet to the reactor. It was concluded that it is possible
to use biological denitrification for drinking water. Post-treatment in an aerated reactor will be needed to ensure
that no carbon or nitrite-nitrogen comes into the potable water.
| Original language | Swedish |
|---|---|
| Pages (from-to) | 323-333 |
| Journal | Vatten: tidskrift för vattenvård /Journal of Water Management and research |
| Volume | 62 |
| Issue number | 4 |
| Publication status | Published - 2006 |
Subject classification (UKÄ)
- Chemical Engineering
- Water Engineering