Urban waste water treatment per province and river basin district

Changed on: 21/03/2025 06:30

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	2023	313	0	1	61	49	45	119	2	12	11	1	0	10	2	29,995	0	54	10,011	4,362	1,197	9,990	91	1,492	1,502	91	0	843	363	23,630	0	60	8,091	3,260	958	7,738	72	1,124	1,320	60	0	692	255	2,245,264	26,036	1,003,290	409,401	92,983	12,757	.	.	.	.	.	.	.	.	2,245,264	2,114	76,385	8,590	15,157	1,773	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.
Noord-Nederland (LD)	2023	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	260,645	2,692	105,180	44,603	9,278	1,368	.	.	.	.	.	.	.	.	260,645	252	9,922	957	1,383	175	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.
Oost-Nederland (LD)	2023	81	0	0	12	13	20	24	0	4	3	0	0	4	1	6,812	0	0	1,522	1,684	404	2,318	0	585	115	0	0	162	23	5,170	0	0	1,178	1,218	319	1,749	0	464	95	0	0	130	18	447,106	5,998	233,702	92,162	20,813	2,869	.	.	.	.	.	.	.	.	447,106	436	15,271	1,464	3,191	441	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.
West-Nederland (LD)	2023	121	0	0	25	21	6	56	1	5	5	0	0	2	0	13,382	0	0	4,582	1,860	98	4,811	51	585	927	0	0	468	0	10,344	0	0	3,548	1,421	77	3,683	40	410	779	0	0	386	0	984,537	11,363	430,439	183,371	42,037	5,425	.	.	.	.	.	.	.	.	984,537	910	32,267	3,792	6,839	723	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.
Zuid-Nederland (LD)	2023	50	0	0	15	5	14	11	0	0	1	0	0	4	0	6,432	0	0	3,255	443	615	1,543	0	0	363	0	0	212	0	5,586	0	0	2,865	334	503	1,336	0	0	372	0	0	176	0	552,976	5,982	233,968	89,264	20,855	3,094	.	.	.	.	.	.	.	.	552,976	516	18,925	2,377	3,744	434	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.
Groningen (PV)	2023	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	85,784	826	33,052	13,647	2,673	406	.	.	.	.	.	.	.	.	85,784	94	3,699	460	571	58	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.
Fryslân (PV)	2023	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	106,597	1,093	41,869	18,382	3,931	585	.	.	.	.	.	.	.	.	106,597	94	3,938	281	446	77	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.
Drenthe (PV)	2023	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	68,264	773	30,259	12,574	2,674	377	.	.	.	.	.	.	.	.	68,264	64	2,285	216	366	40	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.
Overijssel (PV)	2023	32	0	0	9	6	10	2	0	1	2	0	0	1	1	2,196	0	0	899	632	290	218	0	21	90	0	0	22	23	1,740	0	0	703	508	223	182	0	14	75	0	0	17	18	146,451	1,803	69,947	26,868	6,306	868	.	.	.	.	.	.	.	.	146,451	145	5,430	455	1,023	126	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.
Flevoland (PV)	2023	5	0	0	0	1	0	4	0	0	0	0	0	0	0	765	0	0	0	65	0	700	0	0	0	0	0	0	0	612	0	0	0	52	0	560	0	0	0	0	0	0	0	31,339	630	23,657	10,560	2,375	313	.	.	.	.	.	.	.	.	31,339	29	1,053	83	216	21	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.
Gelderland (PV)	2023	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	269,316	3,566	140,099	54,734	12,132	1,689	.	.	.	.	.	.	.	.	269,316	262	8,788	926	1,952	294	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.
Utrecht (PV)	2023	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	142,163	1,790	68,523	28,400	6,455	815	.	.	.	.	.	.	.	.	142,163	112	4,220	429	850	78	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.
Noord-Holland (PV)	2023	30	0	0	8	5	3	8	1	3	2	0	0	0	0	4,565	0	0	1,930	1,038	82	785	51	433	246	0	0	0	0	3,696	0	0	1,713	781	63	581	40	305	213	0	0	0	0	315,490	3,937	148,089	68,846	14,767	1,923	.	.	.	.	.	.	.	.	315,490	337	11,596	1,411	2,348	228	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.
Zuid-Holland (PV)	2023	53	0	0	3	12	3	32	0	1	2	0	0	0	0	5,908	0	0	1,833	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	467,107	5,127	195,941	78,582	18,638	2,444	.	.	.	.	.	.	.	.	467,107	403	14,374	1,643	3,213	357	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.
Zeeland (PV)	2023	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	59,777	508	17,886	7,543	2,177	243	.	.	.	.	.	.	.	.	59,777	59	2,077	309	428	60	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.
Noord-Brabant (PV)	2023	33	0	0	11	2	14	5	0	0	1	0	0	0	0	4,386	0	0	2,772	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	384,884	4,182	164,280	64,398	14,419	2,280	.	.	.	.	.	.	.	.	384,884	335	12,705	1,412	2,440	315	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.
Limburg (PV)	2023	17	0	0	4	3	0	6	0	0	0	0	0	4	0	2,046	0	0	484	427	0	922	0	0	0	0	0	212	0	1,653	0	0	365	323	0	790	0	0	0	0	0	176	0	168,091	1,800	69,688	24,866	6,436	814	.	.	.	.	.	.	.	.	168,091	181	6,219	965	1,303	119	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.
The river Eems	2023	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	91,423	911	36,425	15,219	2,953	438	.	.	.	.	.	.	.	.	91,423	105	4,070	508	628	62	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.
The river Rijn (North Rijn)	2023	38	0	1	0	5	4	23	1	2	1	1	0	0	0	1,521	0	54	0	178	45	918	40	153	41	91	0	0	0	1,157	0	60	0	127	33	678	32	134	33	60	0	0	0	122,917	1,237	47,444	20,700	4,435	662	.	.	.	.	.	.	.	.	122,917	109	4,478	336	537	90	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.
The river Rijn (East Rijn)	2023	73	0	0	13	14	15	23	0	2	2	0	0	3	1	6,863	0	0	1,515	1,742	385	2,825	0	190	90	0	0	92	23	5,178	0	0	1,174	1,284	299	2,137	0	130	75	0	0	61	18	438,362	5,930	230,557	90,572	20,697	2,819	.	.	.	.	.	.	.	.	438,362	412	14,865	1,183	2,865	341	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.
The river Rijn (Central Rijn)	2023
The river Rijn (West Rijn)	2023	114	0	0	15	22	10	51	1	7	6	0	0	2	0	13,096	0	0	4,241	1,896	145	4,247	51	1,062	952	0	0	502	0	10,209	0	0	3,338	1,442	116	3,244	40	802	799	0	0	429	0	968,258	11,359	432,817	184,481	41,482	5,447	.	.	.	.	.	.	.	.	968,258	906	31,695	3,843	6,914	781	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.
The river Maas	2023	52	0	0	14	3	14	16	0	0	1	0	0	4	0	6,079	0	0	2,784	427	606	1,686	0	0	363	0	0	212	0	5,242	0	0	2,428	323	496	1,448	0	0	372	0	0	176	0	519,904	5,651	220,978	84,732	19,722	2,904	.	.	.	.	.	.	.	.	519,904	478	17,404	2,281	3,413	376	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.
The river Schelde	2023	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	104,399	949	35,069	13,697	3,694	486	.	.	.	.	.	.	.	.	104,399	104	3,873	438	800	124	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.
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 21 March 2025:
The figures of 2023 has been added.

When will new figures be published?
New figures on 2024 will be published by March 2026.

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