Table 1.
Concentration of PAHs at various stages of sewage treatment (ng/L).
| Date | Stage | 2-Rings | 3-Rings | 4-Rings | ∑LMW PAHs | ∑HMW PAHs | ∑PAHs | ||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| NAP | ANE | ANA | FLU | PYR | BaA | CHR | |||||
| 23 November | IN | 335.66 | 21.06 | 50.82 | 56.49 | 19.14 | 48.06 | 23.13 | 464.03 | 90.33 | 554.36 |
| EG | 85.15 | 19.78 | 38.33 | 36.13 | 16.14 | 46.17 | 20.87 | 179.39 | 83.18 | 262.57 | |
| AS | 55.91 | 29.16 | 39.83 | 35.95 | 15.36 | 47.90 | 23.70 | 160.85 | 86.96 | 247.81 | |
| EA | 86.19 | 18.41 | 30.51 | 26.41 | 14.95 | 49.47 | 22.44 | 161.52 | 86.86 | 248.38 | |
| ES | 100.19 | 15.25 | 29.27 | 25.03 | 15.54 | 51.04 | 25.04 | 169.74 | 91.63 | 261.37 | |
| FE | 43.51 | 11.13 | 28.07 | 22.37 | 14.73 | 49.18 | 23.44 | 105.08 | 87.35 | 192.44 | |
| 2 December | IN | 449.82 | 16.64 | 28.88 | 43.49 | 22.43 | 47.45 | 22.05 | 538.84 | 91.93 | 630.77 |
| EG | 142.31 | 16.16 | 24.46 | 28.46 | 21.53 | 41.39 | 21.27 | 211.39 | 84.19 | 295.58 | |
| AS | 103.53 | 14.86 | 24.19 | 27.51 | 22.37 | 44.11 | 18.42 | 170.09 | 84.90 | 254.99 | |
| EA | 108.20 | 14.04 | 22.62 | 29.25 | 19.62 | 46.94 | 21.04 | 174.11 | 87.60 | 261.70 | |
| ES | 84.94 | 13.97 | 20.88 | 25.70 | 29.07 | 42.15 | 18.21 | 145.50 | 89.44 | 234.93 | |
| FE | 55.66 | 13.69 | 20.83 | 25.34 | 16.24 | 39.18 | 18.70 | 115.52 | 74.12 | 189.64 | |
| 9 December | IN | 480.58 | 27.31 | 41.74 | 59.41 | 36.59 | 51.87 | 25.75 | 609.04 | 114.21 | 723.24 |
| EG | 217.03 | 18.90 | 31.12 | 37.77 | 24.83 | 43.08 | 18.33 | 304.81 | 86.24 | 391.05 | |
| AS | 73.94 | 14.53 | 26.56 | 28.68 | 21.56 | 45.19 | 21.04 | 143.70 | 87.79 | 231.49 | |
| EA | 58.82 | 13.36 | 22.95 | 27.69 | 21.83 | 45.34 | 20.14 | 122.81 | 87.32 | 210.13 | |
| ES | 51.19 | 12.87 | 21.71 | 23.77 | 21.04 | 46.37 | 22.07 | 109.55 | 89.49 | 199.04 | |
| FE | 107.75 | 17.02 | 25.19 | 28.54 | 24.24 | 42.54 | 17.46 | 178.49 | 84.23 | 262.73 | |
| 17 December | IN | 475.85 | 29.38 | 43.63 | 60.99 | 33.21 | 45.57 | 20.71 | 609.85 | 99.48 | 709.33 |
| EG | 171.78 | 16.11 | 29.97 | 30.73 | 20.77 | 40.36 | 15.81 | 248.59 | 76.94 | 325.53 | |
| AS | 51.55 | 13.77 | 24.80 | 26.77 | 18.63 | 40.18 | 15.95 | 116.90 | 74.76 | 191.66 | |
| EA | 126.31 | 13.49 | 28.28 | 30.83 | 20.97 | 40.54 | 15.76 | 198.91 | 77.27 | 276.18 | |
| ES | 92.23 | 13.40 | 25.07 | 27.36 | 20.14 | 40.02 | 15.64 | 158.07 | 75.81 | 233.88 | |
| FE | 113.67 | 13.58 | 24.51 | 28.86 | 19.21 | 39.42 | 15.43 | 180.62 | 74.06 | 254.67 | |
IN = influent; EG = the effluent of grit chamber; AS = the water-sludge mixture in aerobic stage; EA = the effluent of inverted A2/O tank; ES = the effluent of the secondary clarifier; FE = the final effluent after chlorination; DS = dewatered sludge.