Urban waste water treatment per province and river basin district

Changed on: 12/05/2022 02:00

Urban waste water treatment per province and river basin district
Regions	Periods	Urban waste water treatment plants Numbers by type Total number (number)	Urban waste water treatment plants Numbers by type Trickling filters (number)	Urban waste water treatment plants Numbers by type Aeration tanks (number)	Urban waste water treatment plants Numbers by type Oxidation tanks (number)	Urban waste water treatment plants Numbers by type Oxidation ditches (number)	Urban waste water treatment plants Numbers by type Carrousels (number)	Urban waste water treatment plants Numbers by type Discontinuous systems (number)	Urban waste water treatment plants Numbers by type Parallel installations (number)	Urban waste water treatment plants Numbers by type Multi-stage installations (number)	Urban waste water treatment plants Numbers by type Compact installations (number)	Urban waste water treatment plants Numbers by type Nereda granular sludge reactor (number)	Urban waste water treatment plants Numbers by type Hybrid Nereda - active sludge system (number)	Urban waste water treatment plants Capacity pollution equivalents by type Total capacity pollution equivalents (1 000 pollution equivalent)	Urban waste water treatment plants Capacity pollution equivalents by type Trickling filters (1 000 pollution equivalent)	Urban waste water treatment plants Capacity pollution equivalents by type Aeration tanks (1 000 pollution equivalent)	Urban waste water treatment plants Capacity pollution equivalents by type Oxidation tanks (1 000 pollution equivalent)	Urban waste water treatment plants Capacity pollution equivalents by type Oxidation ditches (1 000 pollution equivalent)	Urban waste water treatment plants Capacity pollution equivalents by type Carrousels (1 000 pollution equivalent)	Urban waste water treatment plants Capacity pollution equivalents by type Discontinuous systems (1 000 pollution equivalent)	Urban waste water treatment plants Capacity pollution equivalents by type Parallel installations (1 000 pollution equivalent)	Urban waste water treatment plants Capacity pollution equivalents by type Multi-stage installations (1 000 pollution equivalent)	Urban waste water treatment plants Capacity pollution equivalents by type Compact installations (1 000 pollution equivalent)	Urban waste water treatment plants Capacity pollution equivalents by type Nereda granular sludge reactor (1 000 pollution equivalent)	Urban waste water treatment plants Capacity pollution equivalents by type Hybrid Nereda - active sludge system (1 000 pollution equivalent)	Influent waste water Quantities Volume waste water (1 000 m3)	Influent waste water Quantities Pollution Equivalents (1 000 pollution equivalent)	Influent waste water Quantities Chemical oxygen demand (COD) (1 000 kg)	Influent waste water Quantities Biochemical oxygen demand (BOD) (1 000 kg)	Influent waste water Quantities Nitrogen compounds as N (total) (1 000 kg)	Influent waste water Quantities Phosphorus compounds as P (total) (1 000 kg)	Influent waste water Quantities Copper (kg)	Influent waste water Quantities Chromium (kg)	Influent waste water Quantities Zinc (kg)	Influent waste water Quantities Lead (kg)	Influent waste water Quantities Cadmium (kg)	Influent waste water Quantities Nickel (kg)	Influent waste water Quantities Mercury (kg)	Influent waste water Quantities Arsenic (kg)	Discharge of waste water (effluent) Quantities Volume waste water (1 000 m3)	Discharge of waste water (effluent) Quantities Pollution Equivalents (1 000 pollution equivalent)	Discharge of waste water (effluent) Quantities Chemical oxygen demand (COD) (1 000 kg)	Discharge of waste water (effluent) Quantities Biochemical oxygen demand (BOD) (1 000 kg)	Discharge of waste water (effluent) Quantities Nitrogen compounds as N (total) (1 000 kg)	Discharge of waste water (effluent) Quantities Phosphorus compounds as P (total) (1 000 kg)	Discharge of waste water (effluent) Quantities Copper (kg)	Discharge of waste water (effluent) Quantities Chromium (kg)	Discharge of waste water (effluent) Quantities Zinc (kg)	Discharge of waste water (effluent) Quantities Lead (kg)	Discharge of waste water (effluent) Quantities Cadmium (kg)	Discharge of waste water (effluent) Quantities Nickel (kg)	Discharge of waste water (effluent) Quantities Mercury (kg)	Discharge of waste water (effluent) Quantities Arsenic (kg)	Sewage sludge Wet sewage sludge by destination Total wet sludge (1 000 kg)	Sewage sludge Wet sewage sludge by destination Agriculture (1 000 kg)	Sewage sludge Wet sewage sludge by destination Wet oxidation (1 000 kg)	Sewage sludge Wet sewage sludge by destination Composting (1 000 kg)	Sewage sludge Wet sewage sludge by destination Landfill (1 000 kg)	Sewage sludge Wet sewage sludge by destination Incineration (1 000 kg)	Sewage sludge Wet sewage sludge by destination Cement industry (1 000 kg)	Sewage sludge Wet sewage sludge by destination Co-incineration at power plants (1 000 kg)	Sewage sludge Wet sewage sludge by destination Other destinations (1 000 kg)	Sewage sludge Dry solids by destination Total dry solids (1 000 kg)	Sewage sludge Dry solids by destination Agriculture (1 000 kg)	Sewage sludge Dry solids by destination Wet oxidation (1 000 kg)	Sewage sludge Dry solids by destination Composting (1 000 kg)	Sewage sludge Dry solids by destination Landfill (1 000 kg)	Sewage sludge Dry solids by destination Incineration (1 000 kg)	Sewage sludge Dry solids by destination Cement industry (1 000 kg)	Sewage sludge Dry solids by destination Co-incineration at power plants (1 000 kg)	Sewage sludge Dry solids by destination Other destinations (1 000 kg)	Sewage sludge Nutrients and heavy metals Ashes (1 000 kg)	Sewage sludge Nutrients and heavy metals Nitrogen compounds as N (1 000 kg)	Sewage sludge Nutrients and heavy metals Phosphorus compounds as P (1 000 kg)	Sewage sludge Nutrients and heavy metals Copper (kg)	Sewage sludge Nutrients and heavy metals Chromium (kg)	Sewage sludge Nutrients and heavy metals Zinc (kg)	Sewage sludge Nutrients and heavy metals Lead (kg)	Sewage sludge Nutrients and heavy metals Cadmium (kg)	Sewage sludge Nutrients and heavy metals Nickel (kg)	Sewage sludge Nutrients and heavy metals Mercury (kg)	Sewage sludge Nutrients and heavy metals Arsenic (kg)
Nederland	2020	315	2	58	56	44	118	1	10	14	1	9	2	29,713	108	10,152	4,615	1,133	9,884	40	956	1,598	91	774	363	1,938,476	27,031	1,056,480	428,585	93,686	13,297	133,000	14,130	433,742	28,269	435	17,391	194	6,449	1,938,476	1,986	72,302	7,512	14,320	1,644	9,156	1,862	68,981	1,244	82	7,143	26	2,603	1,263,335	0	0	0	5,613	1,063,157	14,514	126,468	53,582	308,360	0	0	0	1,480	250,382	13,614	30,765	12,119	91,789	19,111	11,170	120,715	12,003	325,845	25,755	311	7,939	143	3,247
Noord-Nederland (LD)	2020	61	1	9	10	5	29	1	2	2	1	0	1	3,369	54	651	375	81	1,454	40	186	97	91	0	340	222,985	2,812	110,571	44,714	9,589	1,373	15,140	1,667	43,927	2,952	43	1,260	28	604	222,985	255	9,954	906	1,406	170	969	166	5,740	113	10	438	7	256	147,781	0	0	0	990	137,894	0	8,897	0	33,981	0	0	0	278	31,381	0	2,322	0	10,906	2,361	1,233	11,929	1,179	31,138	2,622	25	828	14	328
Oost-Nederland (LD)	2020	83	0	13	13	19	25	0	3	6	0	3	1	6,727	0	1,916	1,684	339	2,270	0	185	211	0	99	23	368,567	6,210	244,548	98,632	21,150	3,027	27,116	3,020	101,902	5,790	84	3,530	36	1,223	368,567	394	13,786	1,221	2,882	379	1,877	369	16,035	241	12	1,205	3	426	294,380	0	0	0	4,623	149,409	0	113,528	26,820	63,700	0	0	0	1,203	29,237	0	27,419	5,841	19,507	4,024	2,198	24,508	2,632	73,493	4,587	63	1,744	29	612
West-Nederland (LD)	2020	121	1	21	28	6	53	0	5	5	0	2	0	13,218	54	4,357	2,113	98	4,617	0	585	927	0	468	0	886,777	11,853	458,913	187,538	42,025	5,664	58,424	5,483	175,465	14,021	167	6,124	90	3,427	886,777	847	30,268	3,086	6,428	681	3,674	721	25,339	581	43	2,801	14	1,449	562,628	0	0	0	0	531,824	0	4,043	26,761	139,549	0	0	0	0	132,248	0	1,023	6,277	37,779	8,631	4,989	54,395	4,565	140,432	12,785	121	2,986	68	1,835
Zuid-Nederland (LD)	2020	50	0	15	5	14	11	0	0	1	0	4	0	6,399	0	3,227	443	615	1,543	0	0	363	0	207	0	460,147	6,155	242,447	97,701	20,922	3,233	32,320	3,960	112,448	5,505	140	6,476	40	1,195	460,147	490	18,294	2,299	3,605	415	2,637	605	21,867	308	17	2,699	2	471	258,545	0	0	0	0	244,031	14,514	0	0	71,130	0	0	0	0	57,515	13,614	0	0	23,597	4,094	2,750	29,884	3,627	80,782	5,761	102	2,380	32	472
Groningen (PV)	2020	22	0	4	4	2	8	1	1	1	0	0	1	1,017	0	180	110	13	260	40	17	56	0	0	340	73,846	840	33,467	12,870	2,773	398	5,718	445	14,064	838	10	395	11	203	73,846	99	3,930	418	622	51	364	42	1,577	35	1	151	3	66	48,346	0	0	0	0	48,346	0	0	0	11,574	0	0	0	0	11,574	0	0	0	4,583	927	416	5,347	405	12,500	1,030	9	338	5	208
Fryslân (PV)	2020	27	1	0	4	1	19	0	0	1	1	0	0	1,336	54	0	170	16	964	0	0	41	91	0	0	91,459	1,101	41,957	17,190	4,051	566	4,876	821	15,675	1,197	17	517	9	273	91,459	86	3,488	243	414	68	338	79	2,545	57	6	177	3	138	71,852	0	0	0	0	71,852	0	0	0	15,285	0	0	0	0	15,285	0	0	0	4,404	1,045	577	4,308	577	11,718	1,117	10	347	5	99
Drenthe (PV)	2020	12	0	5	2	2	2	0	1	0	0	0	0	1,016	0	471	95	51	230	0	169	0	0	0	0	57,680	870	35,148	14,655	2,765	408	4,547	401	14,188	918	16	349	9	128	57,680	69	2,536	245	369	51	267	45	1,618	22	3	110	1	52	27,583	0	0	0	990	17,695	0	8,897	0	7,122	0	0	0	278	4,522	0	2,322	0	1,919	390	240	2,274	197	6,920	476	5	144	3	21
Overijssel (PV)	2020	32	0	9	6	8	2	0	1	5	0	0	1	2,192	0	893	632	219	218	0	21	186	0	0	23	116,450	1,906	74,967	30,880	6,490	949	9,941	803	34,118	2,440	36	1,215	14	261	116,450	128	4,829	407	918	107	676	69	5,448	71	4	439	1	110	97,620	0	0	0	4,623	85,788	0	7,209	0	17,416	0	0	0	1,203	14,442	0	1,771	0	6,218	1,074	704	8,962	954	25,122	1,620	20	694	9	122
Flevoland (PV)	2020	5	0	0	1	0	4	0	0	0	0	0	0	754	0	0	65	0	689	0	0	0	0	0	0	29,602	674	25,766	11,322	2,453	349	2,014	172	5,562	183	6	162	3	406	29,602	33	1,087	91	243	25	170	33	1,468	13	0	75	0	109	38,833	0	0	0	0	35,815	0	0	3,019	8,432	0	0	0	0	7,877	0	0	555	1,870	577	261	1,932	170	4,955	158	4	126	3	229
Gelderland (PV)	2020	46	0	4	6	11	19	0	2	1	0	3	0	3,781	0	1,023	986	121	1,363	0	164	25	0	99	0	222,516	3,631	143,815	56,430	12,206	1,730	15,161	2,045	62,221	3,168	42	2,154	18	556	222,516	233	7,870	723	1,721	247	1,031	268	9,119	157	8	691	2	207	157,927	0	0	0	0	27,806	0	106,318	23,802	37,853	0	0	0	0	6,919	0	25,648	5,286	11,419	2,373	1,232	13,614	1,508	43,416	2,809	39	925	17	260
Utrecht (PV)	2020	22	0	3	4	0	13	0	0	1	0	1	0	2,084	0	185	108	0	1,340	0	0	19	0	432	0	118,175	1,810	70,994	28,645	6,204	823	8,026	792	27,403	1,668	28	795	13	322	118,175	107	3,893	372	864	69	679	106	4,541	71	1	294	1	86	96,947	0	0	0	0	79,419	0	4,043	13,484	21,095	0	0	0	0	16,716	0	1,023	3,356	5,525	1,388	799	6,609	710	20,923	1,544	17	358	9	131
Noord-Holland (PV)	2020	30	1	8	5	3	8	0	3	2	0	0	0	4,582	54	1,940	1,033	82	795	0	433	246	0	0	0	289,642	4,047	153,901	66,440	14,938	1,963	22,881	1,536	58,175	5,318	54	1,821	32	840	289,642	300	10,244	915	2,169	196	1,323	186	8,419	207	18	730	4	350	153,765	0	0	0	0	140,488	0	0	13,277	49,216	0	0	0	0	46,295	0	0	2,921	12,801	2,829	1,724	20,547	1,489	51,003	4,294	40	1,033	24	521
Zuid-Holland (PV)	2020	54	0	4	14	3	30	0	1	2	0	0	0	5,753	0	1,784	786	16	2,439	0	65	662	0	0	0	428,791	5,438	213,200	84,147	18,729	2,612	23,961	2,856	78,047	6,379	73	3,233	41	1,894	428,791	380	13,922	1,479	2,987	368	1,430	385	10,511	280	19	1,657	8	841	287,673	0	0	0	0	287,673	0	0	0	63,216	0	0	0	0	63,216	0	0	0	17,351	4,081	2,261	24,137	2,135	61,158	6,310	57	1,450	32	1,018
Zeeland (PV)	2020	15	0	6	5	0	2	0	1	0	0	1	0	799	0	448	186	0	43	0	86	0	0	36	0	50,169	559	20,819	8,305	2,154	266	3,555	298	11,841	657	12	275	5	371	50,169	60	2,209	321	408	47	242	45	1,868	23	4	120	1	172	24,243	0	0	0	0	24,243	0	0	0	6,021	0	0	0	0	6,021	0	0	0	2,102	333	205	3,103	232	7,348	637	8	145	3	165
Noord-Brabant (PV)	2020	33	0	11	2	14	5	0	0	1	0	0	0	4,358	0	2,744	16	615	620	0	0	363	0	0	0	312,031	4,393	175,023	71,219	14,507	2,482	25,407	2,543	69,720	3,751	90	3,109	29	698	312,031	327	12,437	1,333	2,388	313	2,229	383	14,926	241	17	1,449	1	259	211,980	0	0	0	0	211,980	0	0	0	49,051	0	0	0	0	49,051	0	0	0	15,782	2,933	1,992	23,800	2,547	57,204	4,179	68	1,402	23	354
Limburg (PV)	2020	17	0	4	3	0	6	0	0	0	0	4	0	2,041	0	484	427	0	922	0	0	0	0	207	0	148,116	1,762	67,424	26,482	6,415	750	6,913	1,417	42,728	1,754	50	3,367	12	497	148,116	163	5,857	966	1,217	102	408	223	6,940	67	1	1,250	0	213	46,565	0	0	0	0	32,051	14,514	0	0	22,078	0	0	0	0	8,464	13,614	0	0	7,815	1,162	758	6,084	1,080	23,578	1,582	34	978	9	118
The river Eems	2020	16	0	7	3	0	4	0	0	1	0	0	1	1,134	0	366	102	0	270	0	0	56	0	0	340	78,835	959	38,332	14,910	3,129	440	6,775	482	15,832	914	11	429	12	188	78,835	121	4,683	475	713	62	461	58	1,557	35	2	164	3	64	48,346	0	0	0	0	48,346	0	0	0	11,574	0	0	0	0	11,574	0	0	0	4,583	927	416	5,347	405	12,500	1,030	9	338	5	208
The river Rijn (North Rijn)	2020	38	1	0	5	4	24	1	1	1	1	0	0	1,521	54	0	178	45	1,054	40	17	41	91	0	0	105,753	1,243	47,463	19,412	4,543	639	5,599	888	18,260	1,356	19	580	10	322	105,753	100	4,013	313	494	81	377	83	3,007	64	7	199	3	158	71,852	0	0	0	0	71,852	0	0	0	15,285	0	0	0	0	15,285	0	0	0	4,404	1,045	577	4,308	577	11,718	1,117	10	347	5	99
The river Rijn (East Rijn)	2020	73	0	13	14	13	23	0	2	5	0	2	1	6,849	0	1,509	1,742	314	2,814	0	190	186	0	72	23	365,571	6,114	239,818	97,276	21,032	2,974	26,145	2,790	104,541	6,002	90	3,171	39	1,214	365,571	381	13,503	1,079	2,773	299	1,849	332	16,472	242	9	1,167	2	429	281,660	0	0	0	5,613	162,661	0	84,808	28,579	62,425	0	0	0	1,480	33,037	0	21,077	6,830	19,007	3,867	2,211	23,488	2,468	73,538	4,661	62	1,704	30	563
The river Rijn (Central Rijn)	2020
The river Rijn (West Rijn)	2020	116	1	17	24	11	49	0	6	6	0	2	0	12,860	54	4,602	1,963	153	4,016	0	662	952	0	459	0	868,245	11,879	462,761	189,110	41,499	5,684	57,983	5,674	169,235	13,717	160	6,423	88	3,110	868,245	826	29,325	2,995	6,282	733	3,549	733	23,990	567	42	2,782	14	1,289	573,616	0	0	0	0	506,953	0	41,660	25,003	140,822	0	0	0	0	125,846	0	9,688	5,288	37,845	8,770	4,977	54,156	4,670	139,057	12,467	119	3,008	67	1,720
The river Maas	2020	52	0	14	3	14	16	0	0	1	0	4	0	6,046	0	2,756	427	606	1,686	0	0	363	0	207	0	430,317	5,699	224,044	89,885	19,474	2,976	31,454	3,643	108,624	5,360	129	5,885	37	1,121	430,317	443	16,415	2,151	3,244	342	2,580	563	21,335	302	18	2,500	2	438	232,913	0	0	0	0	218,399	14,514	0	0	66,010	0	0	0	0	52,396	13,614	0	0	21,230	3,862	2,550	27,499	3,132	75,411	5,324	94	2,211	29	423
The river Schelde	2020	20	0	7	7	2	2	0	1	0	0	1	0	1,302	0	919	202	16	43	0	86	0	0	36	0	89,756	1,136	44,064	17,991	4,009	583	5,044	654	17,250	921	26	904	9	493	89,756	115	4,363	499	814	127	340	93	2,620	34	5	332	1	225	54,946	0	0	0	0	54,946	0	0	0	12,243	0	0	0	0	12,243	0	0	0	4,720	640	439	5,918	750	13,621	1,156	16	332	6	234
Source: CBS.

Explanation of symbols

Table description

This table presents the most significant results of the annual survey Public treatment of urban waste water. The results are presented per province and river basin district (Rijn, Maas, Eems and Schelde) and include:
- number and capacity of the urban waste water treatment plants by type of treatment;
- the volume and concentration of organic matter, nutrients and heavy metals in the waste water running into waste water treatment plants (influent) and the volume of treated waste water (effluent). As of 2017, data on heavy metals are only inventoried for even years.
- the volume and destination of the sludge released, with nutrients and heavy metals. As of 2017, sludge data are only inventoried for even years.
Additional data on urban waste water treatment plants, process technology, energy consumption, generation of energy and sludge dewatering can be accessed on the Dutch version of StatLine.

Data available from: 1981

Status of the figures:
The figures in this table are definitive.

Changes as of 12 May 2022:
The figures of 2020 has been added.
Due to new information on 2019, total influent load of CZV and total Pollution Equivalents of the influent has increased with 4 percent in 2019 compared to the previous version. This results for the two parameters also in small changes in underlying classifications.

When will new figures be published?
New figures on 2021 will be published by March 2023.

Description topics

Urban waste water treatment plants

The number and capacity of urban waste water treatment plants in the Netherlands where nearly all domestic waste water and waste water from the private sector is treated. The plants are all operated by regional water quality control authorities.

Numbers by type

Number of sewage water treatment plants broken down by method of treatment.

Total number: The total number of urban waste water treatment plants in the Netherlands.

Trickling filters: Waste water is sprinkled over a layer of porous stones covered with bacteria (biofilm). Thus, organic compounds in the waste water are degraded.

Aeration tanks: Pre-settled waste water runs through an intensively aerated basin containing active sludge (bacteria). Organic pollutants are degraded by oxygen and active sludge. The treatment process takes up only a short period of time and the sludge load is high which is typical of aeration basins.

Oxidation tanks: Operates by the same principle as the aeration tank but the sludge load is significantly lower. The resulting sludge is highly mineralised and will therefore decompose more slowly.

Oxidation ditches: In oxidation ditches, waste water is directed through a aeration circuit several times. The process takes up 2 or 3 days. Consequently, the sludge load is extremely low.

Carrousels: This technology is chiefly applied in large installations. Typical of carrousels are the depth (between 2 to 4 metres) and the aeration method.

Discontinuous systems: Oxidation basins and oxidation ditches. Waste water is let in batch-controlled.

Parallel installations: Various combinations of treatment systems (so-called 'streets') are applied in one installation.

Multi-stage installations: A serial process consisting of two systems, for instance, a trickling filter and an aeration basin. The waste water runs through both stages.

Compact installations: A system consisting of a basin subdivided into four segments. Waste water flows into the aeration segment. Subsequently, the sludge is separated in the central aeration zone. Then part of the sludge is conditioned in the reaeration zone and led back into the aeration zone. The other part (surplus sludge) is stabilised in the sludge mineralisation zone and subsequently removed.

Nereda granular sludge reactor: In the Nereda granular sludge reactor the wastewater is purified by micro-organism clogged in natural granular structures of high density. These granules have a high biological activity and make it easy to separate the micro-organisms from the treated wastewater.

As from 2019 this new treatment type is distinghuished separately in Statline. In the period 2011-2018 already 4 Nereda systems became operational. Until 2019, these installations were classified as oxidation tanks and/or discontinous systems.

Hybrid Nereda - active sludge system: System consisting of a parallel operated Nereda granular sludge reactor and activated sludge system.

In the Nereda granular sludge reactor the wastewater is purified by micro-organism clogged in natural granular structures of high density. These granules have a high biological activity and make it easy to separate the sludge from the treated wastewater.

In activated sludge systems the wastewater is treated in bassins with flocculated sludge . This sludge clumps exists of microorganisms that feed on the the organic pollution in wastewater.

As from 2019 this new treatment type is distinghuished separately in Statline. In the period 2013-2018 already 2 hybrid Nereda - activated sludge sytems became operational. Until 2019, these installations were classified as parallel installations.

Capacity pollution equivalents by type

Capacity urban waste water treatment plant:
A value that indicates how much organic pollution theoretically can be treated by a waste water treatment plant.

The pollution equivalent is the official unit that quantifies the pollution in waste water; one pollution equivalent = 150 g TOD (Total Oxygen Demand).
One pollution equivalent is the daily quantity of oxygen-demanding material in the waste water of one person. The degree of pollution in the waste water produced by the private sector is also expressed in pollution equivalents.
This unit is used as of 2010, so for previous years no values are available.

Total capacity pollution equivalents

Trickling filters: Waste water is sprinkled over a layer of porous stones covered with bacteria (biofilm). Thus, organic compounds in the waste water are degraded.

Aeration tanks: Pre-settled waste water runs through an intensively aerated basin containing active sludge (bacteria). Organic pollutants are degraded by oxygen and active sludge. The treatment process takes up only a short period of time and the sludge load is high which is typical of aeration basins.

Oxidation tanks: Operates by the same principle as the aeration tank but the sludge load is significantly lower. The resulting sludge is highly mineralised and will therefore decompose more slowly.

Oxidation ditches: In oxidation ditches, waste water is directed through a aeration circuit several times. The process takes up 2 or 3 days. Consequently, the sludge load is extremely low.

Carrousels: This technology is chiefly applied in large installations. Typical of carrousels are the depth (between 2 to 4 metres) and the aeration method.

Discontinuous systems: Oxidation basins and oxidation ditches. Waste water is let in batch-controlled.

Parallel installations: Various combinations of treatment systems (so-called 'streets') are applied in one installation.

Multi-stage installations: A serial process consisting of two systems, for instance, a trickling filter and an aeration basin. The waste water runs through both stages.

Compact installations: A system consisting of a basin subdivided into four segments. Waste water flows into the aeration segment. Subsequently, the sludge is separated in the central aeration zone. Then part of the sludge is conditioned in the reaeration zone and led back into the aeration zone. The other part (surplus sludge) is stabilised in the sludge mineralisation zone and subsequently removed.

Nereda granular sludge reactor: In the Nereda granular sludge reactor the wastewater is purified by micro-organism clogged in natural granular structures of high density. These granules have a high biological activity and make it easy to separate the micro-organisms from the treated wastewater.

As from 2019 this new treatment type is distinghuished separately in Statline. In the period 2011-2018 already 4 Nereda systems became operational. Until 2019, these installations were classified as oxidation tanks and/or discontinous systems.

Hybrid Nereda - active sludge system: System consisting of a parallel operated Nereda granular sludge reactor and activated sludge system.

In the Nereda granular sludge reactor the wastewater is purified by micro-organism clogged in natural granular structures of high density. These granules have a high biological activity and make it easy to separate the sludge from the treated wastewater.

In activated sludge systems the wastewater is treated in bassins with flocculated sludge . This sludge clumps exists of microorganisms that feed on the the organic pollution in wastewater.

As from 2019 this new treatment type is distinghuished separately in Statline. In the period 2013-2018 already 2 hybrid Nereda - activated sludge sytems became operational. Until 2019, these installations were classified as parallel installations.

Influent waste water

Data on concentrations and quantities of pollutants in the waste water running into urban waste water treatment plants (influent).

Quantities

Volume waste water: The annual volume of influent waste water.

Pollution Equivalents: The pollution equivalent is the official unit that quantifies the pollution in waste water; one pollution equivalent = 150 g TOD (Total Oxygen Demand).
One pollution equivalent is the daily quantity of oxygen-demanding material in the waste water of one person. The degree of pollution in the waste water produced by the private sector is also expressed in pollution equivalents.
This unit is used as of 2010, so for previous years no values are available.

Chemical oxygen demand (COD): Chemical oxygen demand (COD). Measure of the amount of oxygen consumed when a substance is degraded chemically.

Biochemical oxygen demand (BOD): Biological oxygen demand (BOD). Measure of the amount of oxygen consumed when a substance is biodegraded.

Nitrogen compounds as N (total): The total amount of nitrogen in organic compounds (e.g. proteins) and inorganic compounds (e.g. nitrate and ammonium)

Phosphorus compounds as P (total): The total amount of phosphates and other phosphorus compounds in waste water, measured as phosphorus (P).

Copper

Chromium

Zinc

Lead

Cadmium

Nickel

Mercury

Arsenic

Discharge of waste water (effluent)

Data on concentrations and quantities of pollutants in treated waste water (effluent) discharged from urban waste water treatment plants.

Quantities

Volume waste water: The annual volume of effluent waste water.

Pollution Equivalents: The pollution equivalent is the official unit that quantifies the pollution in waste water; one pollution equivalent = 150 g TOD (Total Oxygen Demand).
One pollution equivalent is the daily quantity of oxygen-demanding material in the waste water of one person. The degree of pollution in the waste water produced by the private sector is also expressed in pollution equivalents.
This unit is used as of 2010, so for previous years no values are available.

Chemical oxygen demand (COD): Chemical oxygen demand (COD). Measure of the amount of oxygen consumed when a substance is degraded chemically.

Biochemical oxygen demand (BOD): Biological oxygen demand (BOD). Measure of the amount of oxygen consumed when a substance is biodegraded.

Nitrogen compounds as N (total): The total amount of nitrogen in organic compounds (e.g. proteins) and inorganic compounds (e.g. nitrate and ammonium).

Phosphorus compounds as P (total): The total amount of phosphates and other phosphorus compounds in waste water, measured as phosphorus (P).

Copper

Chromium

Zinc

Lead

Cadmium

Nickel

Mercury

Arsenic

Sewage sludge

Residue of treated waste water consisting of suspended solids and excess active sludge (biomass). Sewage sludge is measured including water (see Total wet sludge) or as dry solids.

Wet sewage sludge by destination

The volume of wet sewage sludge, i.e. including water by destination (processing method).

Total wet sludge: Total wet sludge discharged.

Agriculture: Application of manure or soil improver in agriculture. Due to rigid legislation impossible since 1995.

Wet oxidation: Wet oxidation of sludge in so-called VerTech installations: the sludge is oxidised under high pressure in a deep shaft.

Composting

Landfill: Dumping of sludge on regional landfill sites or special sludge depots.

Incineration: Incineration of sludge in special sludge incineration plants or in household waste incinerators.

Cement industry: Co-incineration in cement ovens.

Co-incineration at power plants: Sewage sludge used as a secondary fuel at a power plant.

Other destinations: Mainly reuse.

Dry solids by destination

Discharged sewage sludge in kilogrammes of dry solids by destination (processing method). Dry solid is the residue of sewage sludge after evaporation at 105 degrees centigrade.

Total dry solids

Agriculture: Application of manure or soil improver in agriculture. Due to rigid legislation impossible since 1995.

Wet oxidation: Wet oxidation of sludge in so-called VerTech installations: the sludge is oxidised under high pressure in a deep shaft.

Composting

Landfill: Dumping of sludge on regional landfill sites or special sludge depots.

Incineration: Incineration of sludge in special sludge incineration plants or in household waste incinerators.

Cement industry: Co-incineration in cement ovens.

Co-incineration at power plants: Sewage sludge used as a secondary fuel at a power plant.

Other destinations: Mainly reuse.

Nutrients and heavy metals

The total weight of nutrients and heavy metals removed with the sludge. Most heavy metals adsorb strongly to the sludge particles.

Ashes: The residue of non-inflammable, inorganic matter after incineration.

Nitrogen compounds as N: The total amount of nitrogen in organic compounds (e.g. proteins) and inorganic compounds (e.g. nitrate and ammonium).

Phosphorus compounds as P: The total amount of phosphorus in sewage sludge is analysed as P205 (diphosphorus pentoxide) converted to P total.

Copper

Chromium

Zinc

Lead

Cadmium

Nickel

Mercury

Arsenic