Nitrate removal from wastewater generated in wet Flue Gas Desulphurisation Systems (FGD) in coal-fired power generation using the heterotrophic denitrification method
, , y | 30 sept 2020
Publicado en línea: 30 sept 2020
Páginas: 27 - 34
DOI: https://doi.org/10.2478/oszn-2020-0012
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© 2020 Krzysztof Iskra et al., published by Sciendo
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.
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The wet FGD wastewater characteristics during the studies
| 1 | pH value | - | 8.84 | 8.87 | 8.57 | 7.47 | - |
| 2 | BOD5 | gO2/m3 | 0.73 | 0.87 | 1.11 | 1.39 | 1.0 |
| 3 | COD | gO2/m3 | 209 | 213 | 246 | 222 | 222.5 |
| 4 | Total nitrogen (Ntotal) | gN/m3 | 233 | 68.2 | 87.7 | 101.9 | 122.7 |
| 5 | Kjeldahl nitrogen (TKN) | gN/m3 | 43.2 | 21.9 | 35.9 | 0.97 | 25.5 |
| 6 | Ammonium nitrogen (N-NH4) | gN/m3 | 30.5 | 14.9 | 19.6 | 0.62 | 16.4 |
| 7 | Nitrate nitrogen (N-NO3) | gN/m3 | 185.2 | 53 | 58 | 100.9 | 99.3 |
| 8 | Nitrite nitrogen (N-NO2) | gN/m3 | 4.61 | 0,84 | 1.1 | 0.03 | 1.6 |
| 9 | Total phosphorus (P) | gP/m3 | 7.5 | 5.73 | 1.7 | - | 5.0 |
| 10 | Orthophosphates (P-PO4) | gP/m3 | 0.043 | 0.18 | 0.07 | 0.03 | 0.1 |
| 11 | Total suspended solids (TSS) | g/m3 | 422 | 392 | 212 | 69 | 273.8 |
| 12 | Chlorides (Cl−) | g/m3 | 35400 | 19200 | 18500 | 16000 | 22275.0 |
| 13 | Sulphates (SO42−) | g/m3 | 1186 | 1100 | 1227 | - | 1171.0 |
The summary of methods used for wet FGD wastewater treatment
| 1 | Simplified methods | Operation does not require qualified service Resilience to changes in the FGD technology | Large area required for use of lagoons for wastewater / sediment disposal | No |
| 2 | Chemical methods | Small installation volume (short time chemical reaction) Technology with a wide range of both customization and control strategy options | High demand for chemical reagents | No |
| Biological methods | ||||
| 3 | Treatment reactors | Lower maintenance costs compared to chemical methods Consuming less chemical reagents | Operation requires qualified staff Small resilience to changes in wastewater composition | Yes |
| 4 | Hydrophyte wastewater treatment plants | Possibility of achieving parameters similar to those for treatment reactors | Large area required Significant reduction in the efficiency of wastewater treatment at low temperatures | Yes |
| Physical methods | ||||
| 5 | Evaporative methods | A significant reduction in the amount of generated wastewater | High maintenance costs of concentrating wastewater on evaporators | No |
| 6 | Membrane methods | Lower maintenance costs compared to evaporative methods | The need for frequent flushing of membranes High risk of precipitation of mineral salts on the surface of membranes (fouling) High investment costs | Yes1 |
| 7 | Ion exchange methods | In the case of an existing ion exchange installation at the facility, the extension will take lower investment costs | Need for frequent ionites regeneration Higher efficiency of sulphate ion exchange than nitrate ion | Yes |