Discharges via municipal wastewater treatment plants has decreased
Statistical news from Statistics Sweden and Swedish Environmental Protection Agency 2018-04-03 9.30
In 2016, total discharges of nutrients to water via municipal wastewater treatment plants subject to authorisation amounted to 240 tonnes of phosphorus, 15 400 tonnes of nitrogen, 6 600 tonnes of biochemical oxygen demand (BOD7) and 35 300 tonnes of chemical oxygen demand (COD-Cr), including some wastewater overflow at the wastewater treatment plants.
| Major drainage area | Tot-P | Tot-N | NH4-N | BOD7 | CODCr |
|---|---|---|---|---|---|
| Bothnian Bay | 12 | 1 403 | 760 | 675 | 2 213 |
| Bothnian Sea | 34 | 3 599 | 2 187 | 1 163 | 5 244 |
| Baltic Sea | 100 | 5 946 | 1 877 | 2 308 | 14 067 |
| The Sound (Öresund) | 23 | 974 | 482 | 494 | 3 082 |
| Kattegat | 62 | 3 227 | 1 567 | 1 858 | 9 934 |
| Skagerrak | 5 | 265 | 80 | 112 | 716 |
| Total 2016 | 237 | 15 414 | 6 953 | 6 612 | 35 257 |
| Total 2014 | 260 | 15 743 | 7 907 | 7 549 | 44 496 |
Discharges from municipal wastewater treatment plants have decreased since 2014, despite an increased load of phosphorus and BOD7. The average nitrogen removal rate remains unchanged at 62 percent, but for phosphorus and BOD7, the rate has increased slightly.
| Phosphorous | Nitrogen | BOD7 | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| In | Out | Rate of removal | In | Out | Rate of removal | In | Out | Rate of removal | ||
| tonnes | tonnes | % | tonnes | tonnes | % | tonnes | tonnes | % | ||
| Total 2016 | 5 546 | 237 | 96 | 41 049 | 15 414 | 62 | 215 488 | 6 612 | 97 | |
| Total 2014 | 5 176 | 260 | 95 | 41 340 | 15 743 | 62 | 208 340 | 7 549 | 96 | |
Agricultural use is now the most common use of sewage sludge
In 2016, sewage sludge used on farmland became the single most common use of sewage sludge from Swedish municipal wastewater treatment plants. The sum of sewage sludge used in agriculture is estimated to about 69 500 tonnes dry substance, corresponding to 34 percent of total net production. Compared with the use of sludge on farmland in 2014, it constitutes an increase of 36 percent. Plant soil, with both high and normal concentrations of phosphorus, was the second most common use of sewage sludge, at 55 600 tonnes, corresponding to 27 percent of net production. The third most common use was as landfill cover, in order to establish a plant layer at 44 500 tonnes, corresponding to 22 percent of net production. The use of sewage sludge for plant soil or landfill cover decreased by six percent compared with 2014.
The total production of sewage sludge (dry substance) by wastewater treatment plants was estimated at about 204 000 tonnes in 2016. This sewage sludge was produced by 451 wastewater treatment plants.
| Year | Sewage sludge use categories | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Production (tonnes) | Farmland | Forest land | Plant soil normal P | Plant soil high P | Landfill cover | Incineration, no P extraction | Incineration, P extraction | Landfill | Other use | Storage | Use not specified | ||
| 2016 | 204 253 | 69 506 | 150 | 23 908 | 31 733 | 44 506 | 4 154 | 0 | 3 060 | 14 368 | 11 157 | 1 711 | |
| 2014 | 200 510 | 50 950 | 570 | 20 130 | 38 980 | 47 520 | 1 790 | 380 | 3 560 | 20 040 | 13 650 | 2 940 | |
| 2012 | 207 460 | 48 340 | 1 280 | 25 510 | 41 140 | 47 450 | 1 290 | 190 | 7 130 | 23 580 | 2 470 | 9 080 | |
| 2010 | 203 520 | 50 460 | 1 680 | 26 710 | 38 500 | 41 490 | 2 220 | 230 | 7 540 | 17 260 | 17 390 | 40 | |
| 2008 | 213 790 | 55 640 | 1 920 | 17 580 | 40 510 | 42 510 | 330 | 130 | 6 240 | 15 180 | 6 790 | 26 990 | |
| Average values, mg/kg TS | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Population equivalent (pe) | |||||||||||||
| –20 000 | 20 001–100 000 | 100 001– | Total 2016 | Total 2014 | Total 2012 | Total 2010 | Total 2008 | Total 2006 | Total 2004 | Total 2002 | Total 2000 | ||
| Phosphorus | 18 765 | 26 600 | 31 494 | 26 857 | 26 360 | 26 410 | 27 640 | 27 740 | 26 977 | 28 145 | 27 717 | 27 810 | |
| Nitrogen | 37 716 | 42 897 | 51 280 | 45 330 | 45 150 | 43 010 | 44 080 | 42 590 | 42 050 | 40 093 | 37 864 | 38 537 | |
| Cadmium | 0.7 | 0.9 | 0.7 | 0.8 | 0.9 | 1.0 | 0.9 | 0.8 | 1 | 1 | 1.3 | 1.1 | |
| Chromium | 20.5 | 25.1 | 23.0 | 23.1 | 24.2 | 28.0 | 28.8 | 28.3 | 29.3 | 28.9 | 29.7 | 31 | |
| Copper | 281.4 | 346.4 | 373.8 | 342.8 | 348.0 | 352.7 | 347.3 | 335.3 | 357.9 | 345.9 | 370.3 | 373.4 | |
| Mercury | 0.3 | 0.4 | 0.5 | 0.5 | 0.5 | 0.6 | 0.6 | 0.6 | 0.8 | 0.9 | 0.9 | 1 | |
| Nickel | 13.2 | 15.1 | 19.4 | 16.5 | 16.3 | 17.4 | 16.6 | 16.9 | 18.8 | 20.3 | 17.1 | 16.7 | |
| Lead | 13.5 | 16.1 | 17.4 | 16.1 | 19.4 | 22.1 | 21.9 | 22.4 | 27.5 | 24.6 | 30.7 | 33.8 | |
| Zink | 497.8 | 603.5 | 589.9 | 572.0 | 568.2 | 601.5 | 570.1 | 544.3 | 551.5 | 508.3 | 548.6 | 549.4 | |
| Nonylphenol | 2.9 | 5.3 | 9.0 | 6.4 | 7.2 | 8.6 | 10.3 | 10.6 | 14.8 | 14.9 | 17.2 | 17.5 | |
| PAH | 0.37 | 0.55 | 0.95 | 0.68 | 0.85 | 0.88 | 0.94 | 0.98 | 0.7 | 0.9 | 1 | 1.2 | |
| PCB | 0.02 | 0.03 | 0.04 | 0.03 | 0.05 | 0.04 | 0.04 | 0.05 | 0.1 | 0.1 | 0.1 | 0.1 | |
The statistics are now available in the statistical database
The statistics published in the above mentioned Statistical Reports regarding 2016 and 2014 are now available in Statistics Sweden’s statistical database. The aim has been to reproduce the tables shown in the Statistical Report as precisely as possible to help users of the statistics to easily find the requested data. In the statistical database, the tables can be tailored by selecting the variables and groups that fit users’ needs. It is also possible to export the statistics to other file formats for further analysis.
Publication
More detailed statistics about discharges to water from municipal wastewater treatment plants can be found in the Statistical Report Discharges to water and sewage sludge production in 2016.
Statistical Database
More information is available in the Statistical Database
Feel free to use the facts from this statistical news but remember to state Source: Statistics Sweden.