Urban waste water treatment per province and river basin district

Changed on: 29/05/2026 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 Mechanical treatment (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 Membrane bioreactor (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 Mechanical treatment (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 Membrane bioreactor (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)	Urban waste water treatment plants Capacity inhabitant equivalents by type Total capacity inhabitant equivalents (1 000 inhabitant equivalents)	Urban waste water treatment plants Capacity inhabitant equivalents by type Mechanical treatment (1 000 inhabitant equivalents)	Urban waste water treatment plants Capacity inhabitant equivalents by type Trickling filters (1 000 inhabitant equivalents)	Urban waste water treatment plants Capacity inhabitant equivalents by type Aeration tanks (1 000 inhabitant equivalents)	Urban waste water treatment plants Capacity inhabitant equivalents by type Oxidation tanks (1 000 inhabitant equivalents)	Urban waste water treatment plants Capacity inhabitant equivalents by type Oxidation ditches (1 000 inhabitant equivalents)	Urban waste water treatment plants Capacity inhabitant equivalents by type Carrousels (1 000 inhabitant equivalents)	Urban waste water treatment plants Capacity inhabitant equivalents by type Discontinuous systems (1 000 inhabitant equivalents)	Urban waste water treatment plants Capacity inhabitant equivalents by type Parallel installations (1 000 inhabitant equivalents)	Urban waste water treatment plants Capacity inhabitant equivalents by type Multi-stage installations (1 000 inhabitant equivalents)	Urban waste water treatment plants Capacity inhabitant equivalents by type Compact installations (1 000 inhabitant equivalents)	Urban waste water treatment plants Capacity inhabitant equivalents by type Membrane bioreactor (1 000 inhabitant equivalents)	Urban waste water treatment plants Capacity inhabitant equivalents by type Nereda granular sludge reactor (1 000 inhabitant equivalents)	Urban waste water treatment plants Capacity inhabitant equivalents by type Hybrid Nereda - active sludge system (1 000 inhabitant equivalents)	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	2024	313	0	1	61	49	45	119	2	12	11	1	0	10	2	30,019	0	54	10,101	4,363	1,194	9,934	91	1,478	1,502	91	0	849	363	23,630	0	60	8,091	3,260	958	7,738	72	1,124	1,320	60	0	692	255	2,229,171	26,382	1,018,038	421,894	95,026	12,958	122,629	14,602	465,146	28,851	298	17,184	118	7,007	2,229,171	2,130	79,073	8,701	15,127	1,713	9,380	2,336	82,683	1,680	57	7,587	16	2,879	1,349,356	0	0	0	803	917,891	11,285	406,585	12,792	303,272	0	0	0	170	219,129	7,642	73,682	2,650	98,816	17,267	10,799	107,508	12,060	346,209	26,073	316	8,099	134	3,742
Noord-Nederland (LD)	2024	61	0	1	9	10	5	28	1	3	2	1	0	0	1	3,369	0	54	651	375	81	1,318	40	322	97	91	0	0	340	2,531	0	60	501	288	59	970	32	250	74	60	0	0	237	246,983	2,600	98,326	44,135	9,726	1,373	12,030	1,836	43,760	2,728	31	1,570	16	743	246,983	251	10,035	1,054	1,336	170	1,503	390	7,665	246	11	652	3	332	148,148	0	0	0	0	93,440	0	54,708	0	33,940	0	0	0	0	21,603	0	12,337	0	9,995	1,772	1,154	10,621	1,417	34,959	2,953	27	807	13	346
Oost-Nederland (LD)	2024	81	0	0	12	13	20	24	0	4	3	0	0	4	1	6,724	0	0	1,488	1,684	404	2,268	0	580	115	0	0	162	23	5,170	0	0	1,178	1,218	319	1,749	0	464	95	0	0	130	18	444,237	6,109	238,586	96,509	21,267	2,879	21,423	2,357	84,046	4,337	49	2,842	20	1,071	444,237	433	15,771	1,494	3,134	427	1,903	376	17,626	264	6	1,300	2	417	344,432	0	0	0	0	89,367	0	254,875	190	62,382	0	0	0	0	22,649	0	39,692	41	20,483	3,748	2,138	20,535	2,507	73,681	4,957	63	1,558	26	628
West-Nederland (LD)	2024	121	0	0	25	21	6	56	1	5	5	0	0	2	0	13,368	0	0	4,586	1,861	95	4,805	51	575	927	0	0	468	0	10,344	0	0	3,548	1,421	77	3,683	40	410	779	0	0	386	0	955,693	11,642	444,842	191,786	42,715	5,640	49,884	5,059	170,390	13,484	138	5,714	61	3,487	955,693	895	32,724	3,783	6,775	690	3,425	740	26,265	681	31	2,545	8	1,401	536,293	0	0	0	803	431,390	11,285	80,740	12,076	128,705	0	0	0	170	101,082	7,642	17,341	2,470	37,050	7,618	4,553	46,323	3,943	135,580	10,998	116	3,079	59	2,061
Zuid-Nederland (LD)	2024	50	0	0	15	5	14	11	0	0	1	0	0	4	0	6,557	0	0	3,375	443	615	1,543	0	0	363	0	0	218	0	5,586	0	0	2,865	334	503	1,336	0	0	372	0	0	176	0	582,258	6,031	236,283	89,464	21,317	3,067	39,292	5,350	166,950	8,302	80	7,058	22	1,706	582,258	551	20,544	2,370	3,882	427	2,550	830	31,126	490	9	3,089	3	730	320,483	0	0	0	0	303,694	0	16,262	526	78,244	0	0	0	0	73,795	0	4,311	138	31,287	4,130	2,953	30,030	4,193	101,989	7,164	110	2,655	36	707
Groningen (PV)	2024	22	0	0	4	4	2	8	1	1	1	0	0	0	1	1,017	0	0	180	110	13	260	40	17	56	0	0	0	340	741	0	0	130	80	11	195	32	15	41	0	0	0	237	82,343	784	29,058	13,974	3,056	411	4,353	627	11,822	812	7	441	7	252	82,343	100	3,988	524	593	65	325	133	2,068	94	2	152	1	120	49,030	0	0	0	0	0	0	49,030	0	10,875	0	0	0	0	0	0	10,875	0	3,154	394	395	4,241	468	13,050	1,087	11	261	5	122
Fryslân (PV)	2024	27	0	1	0	4	1	18	0	1	1	1	0	0	0	1,336	0	54	0	170	16	828	0	136	41	91	0	0	0	1,006	0	60	0	120	10	604	0	119	33	60	0	0	0	101,801	1,069	40,808	17,898	3,911	573	4,297	815	18,233	1,232	16	730	6	353	101,801	90	3,797	315	406	66	417	183	3,384	94	7	366	1	157	68,166	0	0	0	0	68,166	0	0	0	15,078	0	0	0	0	15,078	0	0	0	4,668	898	499	3,991	725	14,164	1,262	11	389	3	185
Drenthe (PV)	2024	12	0	0	5	2	2	2	0	1	0	0	0	0	0	1,016	0	0	471	95	51	230	0	169	0	0	0	0	0	784	0	0	371	87	38	172	0	116	0	0	0	0	0	62,839	748	28,460	12,264	2,759	388	3,381	394	13,705	685	8	399	4	137	62,839	60	2,250	215	337	40	761	74	2,213	58	2	134	1	55	30,952	0	0	0	0	25,274	0	5,678	0	7,988	0	0	0	0	6,525	0	1,463	0	2,174	480	260	2,389	224	7,745	604	6	158	5	38
Overijssel (PV)	2024	32	0	0	9	6	10	2	0	1	2	0	0	1	1	2,157	0	0	865	632	290	218	0	16	90	0	0	22	23	1,740	0	0	703	508	223	182	0	14	75	0	0	17	18	144,870	1,878	73,764	29,518	6,427	860	7,828	732	29,230	1,717	15	985	6	248	144,870	138	5,451	452	918	112	757	56	6,057	93	1	457	0	98	90,303	0	0	0	0	61,146	0	29,157	0	17,909	0	0	0	0	16,767	0	1,142	0	6,731	1,025	713	8,122	907	24,277	1,840	20	551	10	154
Flevoland (PV)	2024	5	0	0	0	1	0	4	0	0	0	0	0	0	0	715	0	0	0	65	0	650	0	0	0	0	0	0	0	612	0	0	0	52	0	560	0	0	0	0	0	0	0	30,922	635	23,828	10,851	2,414	323	1,677	137	4,612	133	4	139	2	267	30,922	27	977	77	204	19	95	26	1,039	8	0	51	0	46	40,599	0	0	0	0	28,221	0	12,188	190	8,772	0	0	0	0	5,882	0	2,849	41	1,944	607	281	1,816	158	4,545	165	4	126	2	194
Gelderland (PV)	2024	44	0	0	3	6	10	18	0	3	1	0	0	3	0	3,851	0	0	623	986	113	1,400	0	564	25	0	0	140	0	2,818	0	0	475	658	96	1,007	0	450	20	0	0	113	0	268,445	3,596	140,995	56,139	12,426	1,697	11,919	1,488	50,204	2,487	30	1,718	12	555	268,445	268	9,343	965	2,012	297	1,051	294	10,530	162	5	793	1	273	213,530	0	0	0	0	0	0	213,530	0	35,702	0	0	0	0	0	0	35,702	0	11,809	2,116	1,144	10,597	1,442	44,860	2,953	38	880	14	280
Utrecht (PV)	2024	23	0	0	3	4	0	14	0	0	1	0	0	1	0	2,110	0	0	185	108	0	1,365	0	0	19	0	0	432	0	1,680	0	0	145	79	0	1,082	0	0	14	0	0	360	0	137,004	1,831	70,764	29,597	6,511	844	7,468	713	32,802	1,834	17	678	9	308	137,004	118	4,490	492	879	87	703	101	5,443	84	0	258	0	108	90,291	0	0	0	0	71,770	0	18,522	0	20,384	0	0	0	0	15,906	0	4,478	0	5,525	1,333	710	5,825	535	21,696	1,571	16	362	7	141
Noord-Holland (PV)	2024	30	0	0	8	5	3	8	1	3	2	0	0	0	0	4,547	0	0	1,929	1,039	79	779	51	424	246	0	0	0	0	3,696	0	0	1,713	781	63	581	40	305	213	0	0	0	0	313,465	4,181	159,096	74,171	15,412	2,027	21,313	1,686	59,426	4,923	64	1,780	19	896	313,465	319	11,530	1,348	2,228	206	1,364	227	8,750	278	17	773	3	354	151,719	0	0	0	252	68,447	11,285	59,768	11,966	43,446	0	0	0	51	20,972	7,642	12,336	2,444	12,045	2,149	1,471	17,267	1,280	48,855	3,672	47	929	21	565
Zuid-Holland (PV)	2024	53	0	0	3	12	3	32	0	1	2	0	0	0	0	5,913	0	0	1,838	714	16	2,618	0	65	662	0	0	0	0	4,405	0	0	1,242	561	13	1,989	0	46	552	0	0	0	0	446,895	5,145	198,158	80,636	18,647	2,530	19,196	2,313	71,862	5,918	46	2,940	27	2,164	446,895	396	14,493	1,641	3,238	351	1,206	356	10,957	271	10	1,386	4	889	267,889	0	0	0	551	264,779	0	2,450	110	58,749	0	0	0	118	58,077	0	527	26	17,323	3,759	2,179	20,320	1,891	56,846	5,114	47	1,637	27	1,162
Zeeland (PV)	2024	15	0	0	11	0	0	2	0	1	0	0	0	1	0	799	0	0	634	0	0	43	0	86	0	0	0	36	0	563	0	0	447	0	0	31	0	59	0	0	0	26	0	58,329	485	16,824	7,381	2,144	239	1,908	348	6,299	808	11	317	5	119	58,329	62	2,211	301	431	47	151	56	1,115	47	3	128	1	50	26,394	0	0	0	0	26,394	0	0	0	6,127	0	0	0	0	6,127	0	0	0	2,157	377	193	2,910	237	8,183	641	6	151	3	194
Noord-Brabant (PV)	2024	33	0	0	11	2	14	5	0	0	1	0	0	0	0	4,506	0	0	2,892	16	615	620	0	0	363	0	0	0	0	3,933	0	0	2,501	11	503	547	0	0	372	0	0	0	0	395,100	4,183	163,877	64,220	14,781	2,305	33,001	3,522	117,506	5,577	68	4,460	16	994	395,100	364	13,737	1,487	2,616	327	2,034	493	20,436	286	9	1,921	2	412	225,595	0	0	0	0	220,178	0	5,417	0	53,528	0	0	0	0	52,217	0	1,311	0	20,995	2,855	2,110	23,832	2,963	72,558	5,242	79	1,630	27	542
Limburg (PV)	2024	17	0	0	4	3	0	6	0	0	0	0	0	4	0	2,051	0	0	484	427	0	922	0	0	0	0	0	218	0	1,653	0	0	365	323	0	790	0	0	0	0	0	176	0	187,158	1,848	72,406	25,244	6,537	762	6,291	1,828	49,444	2,725	12	2,599	6	713	187,158	186	6,807	884	1,265	99	515	337	10,691	204	NaN	1,168	1	318	94,888	0	0	0	0	83,516	0	10,846	526	24,716	0	0	0	0	21,578	0	3,000	138	10,292	1,274	843	6,198	1,231	29,430	1,921	31	1,025	9	166
The river Eems	2024	16	0	0	7	3	0	4	0	0	1	0	0	0	1	1,134	0	0	366	102	0	270	0	0	56	0	0	0	340	819	0	0	267	73	0	201	0	0	41	0	0	0	237	87,564	867	32,049	15,502	3,403	446	5,163	668	13,218	863	8	469	7	230	87,564	109	4,290	580	630	65	917	152	2,387	123	2	144	2	103	49,030	0	0	0	0	0	0	49,030	0	10,875	0	0	0	0	0	0	10,875	0	3,154	394	395	4,241	468	13,050	1,087	11	261	5	122
The river Rijn (North Rijn)	2024	38	0	1	0	5	4	23	1	2	1	1	0	0	0	1,520	0	54	0	178	44	918	40	153	41	91	0	0	0	1,157	0	60	0	127	33	678	32	134	33	60	0	0	0	117,644	1,211	46,054	20,412	4,471	655	5,122	919	21,127	1,428	19	816	7	411	117,644	105	4,367	372	491	78	464	200	3,781	102	7	394	1	188	68,166	0	0	0	0	68,166	0	0	0	15,078	0	0	0	0	15,078	0	0	0	4,668	898	499	3,991	725	14,164	1,262	11	389	3	185
The river Rijn (East Rijn)	2024	73	0	0	13	14	15	23	0	2	2	0	0	3	1	6,775	0	0	1,481	1,742	385	2,775	0	185	90	0	0	92	23	5,178	0	0	1,174	1,284	299	2,137	0	130	75	0	0	61	18	429,921	5,987	232,848	93,669	21,058	2,827	20,194	2,201	85,145	4,278	45	2,618	18	988	429,921	414	15,636	1,253	2,833	345	1,810	361	17,749	248	4	1,183	2	370	350,517	0	0	0	0	114,641	0	235,686	190	64,216	0	0	0	0	29,174	0	35,000	41	20,396	3,922	2,255	20,610	2,523	75,263	5,171	62	1,557	28	614
The river Rijn (Central Rijn)	2024
The river Rijn (West Rijn)	2024	114	0	0	15	22	10	51	1	7	6	0	0	2	0	13,083	0	0	4,245	1,897	143	4,241	51	1,053	952	0	0	502	0	10,209	0	0	3,338	1,442	116	3,244	40	802	799	0	0	429	0	942,525	11,684	449,323	193,633	42,238	5,668	50,364	5,066	170,524	13,045	134	5,857	59	3,484	942,525	883	31,751	3,794	6,821	746	3,442	730	26,192	663	31	2,627	8	1,410	529,235	0	0	0	803	399,464	11,285	105,607	12,076	127,518	0	0	0	170	93,740	7,642	23,496	2,470	36,846	7,464	4,469	45,332	3,888	132,496	10,662	116	3,068	58	1,890
The river Maas	2024	52	0	0	14	3	14	16	0	0	1	0	0	4	0	6,205	0	0	2,904	427	606	1,686	0	0	363	0	0	218	0	5,242	0	0	2,428	323	496	1,448	0	0	372	0	0	176	0	548,198	5,636	220,825	83,635	19,955	2,840	38,225	4,667	162,084	8,122	81	6,420	22	1,592	548,198	505	18,822	2,234	3,491	369	2,465	725	30,265	480	9	2,824	3	683	295,421	0	0	0	0	278,632	0	16,262	526	73,018	0	0	0	0	68,569	0	4,311	138	28,760	3,905	2,756	27,466	3,581	95,339	6,667	102	2,468	34	623
The river Schelde	2024	20	0	0	12	2	2	2	0	1	0	0	0	1	0	1,302	0	0	1,105	16	16	43	0	86	0	0	0	36	0	1,024	0	0	884	11	13	31	0	59	0	0	0	26	0	103,319	998	36,938	15,043	3,901	523	3,561	1,080	13,048	1,114	12	1,004	5	302	103,319	114	4,206	469	863	110	281	169	2,309	65	4	414	1	126	56,988	0	0	0	0	56,988	0	0	0	12,568	0	0	0	0	12,568	0	0	0	4,992	684	424	5,868	876	15,897	1,223	15	357	6	307
Source: CBS.

Explanation of symbols

Table explanation

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 29 May 2026:
The figures of 2024 has been added.

When will new figures be published?
New figures on 2025 will be published by March 2027.

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.

Mechanical treatment: Installation where suspended matter is extracted from waste water by settlement.

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.

Membrane bioreactor: A system where the sludge is separated from the waste water by using a membrane.

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

Mechanical treatment: Installation where suspended matter is extracted from waste water by settlement.

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.

Membrane bioreactor: A system where the sludge is separated from the waste water by using a membrane.

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 inhabitant 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 capacity expressed in Inhabitant Equivalents is determined on basis of: one inhabitant equivalent = 54 g BOD (Biological Oxygen Demand).
One inhabitant equivalent is the daily quantity of oxygen-demanding, organic substances in the waste water of one person.
Nowadays, the use of the unit inhabitant equivalent is decreasing. The most common unit is the pollution equivalent.

Total capacity inhabitant equivalents: The total capacity of all urban waste water treatment plants.

Mechanical treatment: Installation where suspended matter is extracted from waste water by settlement.

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.

Membrane bioreactor: A system where the sludge is separated from the waste water by using a membrane.

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