Discharges to water and sewage sludge production in 2020

Discharges continues to decrease

Statistical news from Statistics Sweden and Swedish Environmental Protection Agency 2022-11-17 8.00

Statistics Sweden’s latest statistics show that the discharges of phosphorous and nitrogen have decreased since 2018. Discharges to water via municipal wastewater treatment plants have decreased during a longer period.

In 2020, total discharges of nutrients to water via municipal wastewater treatment plants subject to authorisation amounted to 250 tonnes of phosphorous, 15 000 tonnes of nitrogen, 6 000 tonnes of biochemical oxygen demand (BOD₇), and 39 000 tonnes of chemical oxygen demand (COD_Cr), including some wastewater overflow at the plants.

Discharges from municipal wastewater treatment plants in 2020, by sea basin district, and total biannually 1987-2020

Sea basin district	Tot-P	Tot-N	BOD7	COD-Cr
Bothnian Bay	14	1 275	632	2 084
Bothnian Sea	34	3 472	1 100	4 913
Baltic Sea	103	5 966	1 883	18 739
The sound (Öresund)	27	864	419	2 844
Kattegatt	66	2 979	1 686	9 906
Skagerrak	5	223	102	659
Total 2020	249	14 779	5 822	39 145
2018	266	14 982	6 548	40 483
2016	237	15 414	6 612	35 257
2014	260	15 743	7 549	44 496
2012	275	17 120	7 993	47 264
2010	267	17 419	7 908	46 510
2008	313	18 433	7 447	46 893
2006	362	18 347	8 570	50 118
2004	318	17 779	7 869	48 315
2002	351	18 036	8 158	49 903
2000	424	18 977	9 784	57 472
1998	430	21 376	11 270	58 463
1995	470	25 940	13 060	66 840
1992	470	25 310	12 205	62 190
1990	655	26 200	14 050	69 150
1987	1 050	25 600	16 700	66 300

The average removal rate for nitrogen has slightly increased since 2018, while it was unchanged for phosphorous and BOD₇. In a ten years perspective the average removal rate for phosphorous and BOD₇has been stable and increased for nitrogen.

Quantities of phosphorous, nitrogen and BOD7 in incoming wastewater and outgoing, treated, effluent and corresponding rate of removal, biannually 1998-2020

	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 2020	5 095	249	95	41 737	14 779	65	208 770	5 822	97
2018	5 351	266	95	41 294	14 982	64	224 533	6 548	97
2016	5 546	237	96	41 049	15 414	62	215 488	6 612	97
2014	5 176	260	95	41 340	15 743	62	208 340	7 549	96
2012	5 307	275	95	41 967	17 120	59	196 706	7 993	96
2010	5 563	267	95	42 292	17 419	59	202 100	7 908	96
2008	6 346	313	95	42 360	18 433	56	202 717	7 447	96
2006	6 948	362	95	42 956	18 347	57	207 611	8 570	96
2004	7 113	318	96	41 417	17 779	57	207 736	7 869	96
2002	7 090	351	95	40 999	18 036	56	208 201	8 158	96
2000	7 743	424	95	41 269	18 977	54	213 923	9 784	95
1998	6 578	430	94	40 086	21 376	47	207 471	11 271	95

Agricultural use remains the most common application for sewage sludge

Use on arable land agricultural land is the most common application of sewage sludge from municipal wastewater treatment plants in 2020. In 2020, total sewage sludge used in agriculture was estimated to be around 96 000 tonnes of dry substance, corresponding to 46 percent of total net production. This is seven percentage points more than in 2018.

Wastewater treatment plants’ estimated production of sewage sludge (dry substance) was around 208 000 tonnes in 2020, which is 1,5 percent less than in 2018.

Sewage sludge production and use in Sweden, biannually 2008-2020

		Sewage sludge use categories, tonnes
	Production (tonnes)	Arable land	Forest land	Plant soil normal P	Plant soil high P	Landfill cover	Incineration, no P extraction	Incineration	Landfill	Other use	Storage	Use not specified
2020	208 348	96 328	440	26 281	20 981	33 636	5 158	0	1 697	12 252	10 432	1 142
2018	211 604	82 288	137	26 271	27 768	36 199	2 816	0	2 299	21 095	12 466	265
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

Concentrations of nutrients, metals and organic indicator substances in sewage sludge from municipal wastewater treatment plants, by municipal wastewater treatment plant class size, are given in table 4.

Concentrations of nutrients, metals and organic indicator substances in sewage sludge from municipal wastewater treatment plants

	Averages, mg/kg dry substance
	Population equivalent (pe)
	0–20 000	20 001–100 000	100 001–	Total	Total	Total	Total	Total	Total	Total
				2020	2018	2016	2014	2012	2010	2008
Phosphorous	19 292	26 300	31 910	27 162	26 500	26 857	26 360	26 410	27 640	27 740
Nitrogen	38 571	45 546	51 719	46 672	45 934	45 330	45 150	43 010	44 080	42 590
Cadmium	0.8	0.8	0.8	0.8	0.7	0.8	0.9	1	0.9	0.8
Chromium	20.5	24.6	22.1	22.5	22.1	23.1	24.2	28	28.8	28.3
Copper	280.1	310.8	376.6	333.3	335.3	342.8	348	352.7	347.3	335.3
Mercury	0.3	0.4	0.5	0.4	0.5	0.5	0.5	0.6	0.6	0.6
Nickel	14.3	14.8	20.6	17.3	16.8	16.5	16.3	17.4	16.6	16.9
Lead	14.1	15.7	18.4	16.6	16.2	16.1	19.4	22.1	21.9	22.4
Zink	465.1	507.7	527.8	506.5	562.5	572	568.2	601.5	570.1	544.3
Nonylphenol	2.6	2.9	4.7	3.7	4.3	6.4	7.2	8.6	10.3	10.6
PAH	0.29	0.38	1	0.64	0.6	0.68	0.85	0.88	0.94	0.98
PCB	0.01	0.01	0.02	0.02	0	0.03	0.05	0.04	0.04	0.05

These statistics are now available in the Statistical Database

The statistics published in the Statistical Reports on 2020, 2018, 2016, and 2014 are now available in Statistics Sweden’s Statistical Database. There, the tables can be tailored to the user’s needs by selecting specific variables and groups. It is also possible to export the statistics to other file formats for further analysis and to use Statistics Sweden’s API for automated data requests.

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 2020.

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.