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Indicator Assessment
Wastewater treatment in all parts of Europe has improved during the last 15-20 years. The percentage of the population connected to wastewater treatment in the southern, south-eastern and eastern Europe has increased during last ten years, but is still relative low compared to the central and northern Europe.
Changes in wastewater treatment in regions of Europe between 1990 and 2005
Note: Only countries with data from (almost) all periods were included, the numbers of countries are given in parentheses
EEA-ETC/WTR based on country data reported to OECD/EUROSTAT Joint Questionnaire. Data are available at Eurostat data tables.
Changes in wastewater treatment in northern countries of Europe between 1980s and 2005
Note: N/A
EEA-ETC/WTR based on country data reported to OECD/EUROSTAT Joint Questionnaire. Data are available at Eurostat data tables.
Changes in Changes in wastewater treatment in countries of Europe between 1980s and 2005 (Western)
Note: N/A
EEA-ETC/WTR based on country data reported to OECD/EUROSTAT Joint Questionnaire. Data are available at Eurostat data tables.
Changes in wastewater treatment in countries of Europe between 1980s and 2005 (Southern)
Note: N/A
EEA-ETC/WTR based on country data reported to OECD/EUROSTAT Joint Questionnaire. Data are available at Eurostat data tables.
Changes in wastewater treatment in countries of Europe between 1980s and 2005 (East)
Note: N/A
EEA-ETC/WTR based on country data reported to OECD/EUROSTAT Joint Questionnaire. Data are available at Eurostat data tables.
Changes in wastewater treatment in countries of Europe between 1995 and 2005 (South-Eastern)
Note: N/A
EEA-ETC/WTR based on country data reported to OECD/EUROSTAT Joint Questionnaire. Data are available at Eurostat data tables.
The main objective of the Urban Waste Water Treatment (UWWT) Directive is to protect the environment from the adverse effects of urban waste water discharges and discharges from certain industrial sectors and the measures concerns the collection, treatment and discharge of most of the waste water.
As a rule, the UWWT Directive provides for biological waste water treatment (secondary treatment), and thus a drastic reduction of the biodegradable pollution in waste water - which otherwise would severely impact on oxygen balance and ecosystems of our waters. In the catchments of particularly sensitive waters (sensitive areas), such as those suffering from eutrophication, more stringent treatment measures are required, to additionally eliminate nutrient pollution (nitrogen and phosphorus) from waste water (tertiary treatment).
The success indicators used in this assessment to measure the reduction in discharges of nutrients and organic matter from urban waste water to European surface waters are:
1. Percentage of population connected to waste water treatment.
2. Percentage of waste water given tertiary treatment.
1. Percentage of population connected to waste water treatment (Fig. 1 and the individual countries in Fig. 2-6). In northern and also in southern European countries more than 80 % of the population is connected to waste water treatment. In sparcely populated countries with a relative high proportion of the population living in scattered dwellings these dwelling are not connected to collecting systems and normally served by individual waste water treatment (e.g. septic tanks). In central Europe more than 90 % is connected. In eastern Europe only 50 % is connected (last data are from 2002, so this percentage may be higher now), whereas in south-eastern Europe (Turkey, Bulgaria and Romania) there is only 35 % that are connected to waste water treatment plants.
2. Percentage of waste water given tertiary treatment (yellow color on Fig. 1 to 6). Most of the population in the northern countries is connected to waste water treatment plants with the highest levels of treatment (tertiary), which efficiently removes nutrients (phosphorus or nitrogen or both) and organic matter. More than half of the waste water in central European countries is subject to tertiary treatment. In southern and eastern Europe only 20 % get tertiary treatment. Around half of the wastewater in southern European countries and 25 % in eastern Europe receive only secondary treatment. In south-eastern Europe the level of tertiary treatment is minor (< 5 %), whereas 20 % is subject to secondary treatment.
The lastest from 2007 EU Commissions Urban Waste Water Treatment (UWWT) Directive implementation report can be found on http://ec.europa.eu/environment/water/water-framework/implrep2007/index_en.htm. According to this report waste water treatment in 349 out of the 571 big cities of
Further information can be found in the WISE section on Urban Waste Water Treatment Directive http://www.eea.europa.eu/themes/water/water-pollution/prevention-strategies/urban-waste-water-treatment-directive.
Specific assessments of waste water treatment in different countries:
Northern Europe: Most of the waste water (80%) in Finland, Sweden and Norway receives tertiary treatment (Fig. 2), while in Iceland the waste water from half of the population is not treated at all and the other half only receive primary treatment. The trends in the rate of national population connected to the UWWTPs are affected by changes in the ratio of rural/urban population as well as by increasing use of separate individual treatment plants in rural areas.
Central Europe: In
Southern Europe: The best situation is in
Eastern Europe: More than 65 % of the population in the
South-Eastern Europe: In south eastern European countries (
The indicator on urban waste water treatment, WAT005, collects data on the percentage of the population connected to sewage collection systems, as well as on the prevalence of primary, secondary and tertiary urban waste water treatment plants.
The amount of urban waste water treated from 'big cities' is expressed as population equivalents (p.e.).
The indicator illustrates:
The percentages of the population connected to primary, secondary and tertiary urban waste water treatment facilities (Figures 1 and 2).
The percentage of population equivalent (p.e.) was used for “big city” treatment (Figure 3).
The main objective of the Urban Waste Water Treatment Directive (91/271/EEC) (UWWTD), and equivalent national legislation for non-EU countries, is to protect surface waters from the adverse effects of waste water discharges. The UWWTD prescribes the level of treatment required before discharge to surface waters. It requires Member States to provide all urban settlements (called 'agglomerations' in the UWWTD) of more than 2 000 p.e. with collecting systems. Primary (mechanical) and secondary (i.e. biological) treatments must be provided for all agglomerations of more than 2 000 p.e. that discharge into fresh waters. Special requirements, with intermediate deadlines depending on the sensitivity of the receiving waters, are placed on urban settlements of more than 10 000 p.e., with various size classes. The performance of the treatment is assessed using several determinands (biochemical oxygen demand (BOD) and chemical oxygen demand (COD); plus total nitrogen and total phosphorus in the case of more stringent treatment).
For urban settlements smaller than those described above and equipped with a collecting system, the treatment must be 'appropriate', meaning that the discharge must allow the receiving waters to meet the relevant quality standards.
The UWWTD, adopted in 1991, is also a basic measure under the Water Framework Directive (WFD). The WFD requires the estimation and identification of significant point- and diffuse-source pollution, in particular by the substances listed in Annex VIII, from urban, industrial, agricultural and other installations and activities, based, inter alia, on information gathered, for instance, under Articles 15 and 17 of the UWWTD. Based on the substances listed in Annex VIII WFD, the following are important for this indicator:
Member States should thus take the necessary steps to collect these data. Reducing pollutants stemming from waste water is one of the key challenges of reaching good ecological and good chemical status of surface waters, as required by the WFD.
Collecting and treating waste water has required huge investment across Europe in recent decades. The kinds of new challenges facing urban waste water treatment, such as climate change, resource efficiency and improved environmental protection, are set out in the EEA briefing Urban waste water treatment for 21st century challenges.
Further information on emissions from industry to water, including to urban waste water treatment plants, is available in Industrial waste water treatment - pressures on Europe's environment.
The UWWT Directive (91/271/EEC) aims to protect the environment from the adverse effects of urban waste water discharges. It prescribes the level of treatment required before discharge and should have been fully implemented in the EU-15 countries by 2005. For the newer Member States (i.e. the EU-13), staged transition periods were set within the Accession Treaties which, in principle, did not extend beyond 2015. However, in Romania, smaller agglomerations (with less than 10 000 p.e.) should have complied with the directive by the end of 2018, and Croatia has different transition periods, from 2018 to 2023.
Under the directive, EU-15 Member States were required to provide all urban settlements of more than 2 000 p.e. with collecting systems and all waste waters collected had to be provided with appropriate treatment by 2005. Secondary treatment (i.e. biological treatment) must be provided for all urban settlements of more than 2 000 p.e. that discharge into fresh waters, while more advanced treatment (tertiary treatment) is required for discharges into sensitive areas.
The achievements resulting from the UWWTD should be seen as an integral part of achieving good status for all waters under the WFD.
The indicator is based on data from Eurostat, which show the percentage of the population connected to each treatment type. Compared with previous versions of the indicator, Figure 1 now shows the treatment level in EEA member and cooperating countries in 2017, rather than grouping countries according to region.
A p.e. of 1 is equivalent to an organic biodegradable load having a 5-day BOD of 60 g per day.
Tertiary treatment is known in the UWWT Directive as 'treatment more stringent than secondary' and includes the application of secondary treatment.
'Big cities' is a term used in the UWWT Directive for cities of at least 150 000 p.e. or agglomerations responsible for large waste water discharges. Countries themselves identify their 'big cities'.
Gap filling was undertaken on the basis that once an urban waste water infrastructure had been put in place, it was likely to be used in subsequent years. Therefore, any gaps were filled with data from the most recent year reported, e.g. 2016 data carried forward to 2017. This approach was used for up to 5 years of gap filling, i.e. 2012 data could be carried forward to up to 2017.
The main uncertainties relate to data reported to Eurostat. In 2005, treatment for 24 % of the population was 'unknown', which fell to 15 % in 2017. The second area of uncertainty relates to numbers of inhabitants, as these do not necessarily align with reported population data, though error here is generally small.
The 'EU-27' value is strongly influenced by the situation in Member States with large populations (France, Germany, Italy and Spain).
At country level, the population figure and the generated p.e. load are not usually the same, as there can be other sources of organic pollution, such as food industry and temporal changes in population owing e.g. to tourism.
Data reported to Eurostat sometimes provide an incomplete picture of inhabitants connected to waste water treatment (e.g. the percentage of the population connected to urban waste water systems is given, but the percentage for which the waste water is collected without treatment is missing).
'Big cities' data sometimes include data from agglomerations that are much smaller than 150 000 p.e. However, the impact of such errors on the final percentages is rather small.
Data from the UWWT Directive focuses on the performance of the treatment plant and of the agglomeration. However, urban waste water treatment systems could also include sewer networks with storm water overflows and storage, which are complex and therefore overall performance is difficult to assess. In addition to the treatments covered by the UWWT Directive, there are other possible treatments, mostly industrial, but also independent treatments of smaller settlements outside urban agglomerations not included in UWWT Directive reporting. Compliance with the levels defined in the directive therefore does not guarantee that there is no pollution due to urban waste water.
In addition, urban waste water treatment (primary, secondary or tertiary, as described above) is the main waste water treatment used across the EEA area, but there are other possible treatments classified as 'Other Waste Water Treatment', which are mostly industrial or independent treatments. Furthermore, there are differences in how countries have interpreted the definitions of different classes of treatment (classes based on performance or design capacity and tertiary treatment for nitrogen, phosphorus or organic matter) that, in turn, lead to differences in the level of purification attributed by the countries to the different classes. These differences emphasise the problem of using types of treatment plant as a proxy for the level of purification.
For references, please go to https://www.eea.europa.eu/data-and-maps/indicators/urban-waste-water-treatment/urban-waste-water-treatment-assessment-1 or scan the QR code.
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