Table 1.
The percentage (%) reduction of nitrate by ABO-NRB enriched in batch cultures containing 2% (v/v) MHGC oil with or without additional electron donor.
| Designation | Source of ABO-NRB inoculum | Electron donor (mM) added to oil |
Electron acceptor (mM) |
Days of incubation | N2 | Nitrate reduction3 (%) | |
|---|---|---|---|---|---|---|---|
| Ethylbenzene | Toluene | Nitrate | |||||
| B_N | 18PW | 0 | 0 | 80 | 35 | 3 | 2.4 ± 2.3 |
| B_EN | 18PW | 475 | 0 | 80 | 35 | 4 | 20.2 ± 0.8 |
| B_TN | 18PW | 0 | 570 | 80 | 35 | 3 | 41.8 ± 2.0 |
| B_EN_EN | B_EN | 475 | 0 | 901 | 20 | 3 | 25.1 ± 1.4 |
These were either inoculated with produced water 18PW from the MHGC field or ABO-NRB primary enrichment grown on 475 mM ethylbenzene in 1 mL of oil and 80 mM nitrate in 49 mL of aqueous phase (B_EN). Each value represents an average ± SD of three or four replicates. 110 mM on day 0 and 80 mM on day 6. 2Number of replicates. 3Nitrate reduction (%) = (nitrite concentration/initial nitrate concentration)∗40% + ((initial nitrate concentration - residual nitrate concentration - nitrite concentration)/initial nitrate concentration)∗100%.