A3 Urban Waste Water Treatment Directive

A3.1 Legislation

The UWWTD is one of the core elements of EU water policy. Adopted in 1991, it regulates discharges of municipal wastewater from cities, towns and larger villages (called agglomerations) and explicitly specifies what kind of treatment must be applied.

Every second year, Member States report their national data on compliance with the UWWTD to the European Commission. The EEA, consultants and the Commission take different parts in checking these data for good quality and subsequent analysis for compliance with the UWWTD. The data and results are visible within a map viewer (http://www.eea.europa.eu/data-and-maps/uwwtd/interactive-maps/urban-waste-water-treatment-maps-1) while the EC publishes a report summarising compliance (EC 2016).

The directive requires the following:

  • Article 3: All European agglomerations with a size of more than 2 000 population equivalents (p.e.) are equipped with collecting and treatment systems for their wastewaters. The UWWTD uses the term ‘population equivalent’ (p.e.) to measure the size of agglomerations. It is calculated on the basis that the average five-day BOD per person is 60 g of oxygen a day.

  • Article 4: Urban wastewater from agglomerations above 2000 p.e., which enters collecting systems, needs to be subjected to secondary treatment. Wastewater treatment should significantly reduce biodegradable pollution, mainly BOD and chemical oxygen demand, in wastewater.

  • Article 5: “Sensitive areas” are those areas suffering from the enrichment of water by nutrients, especially compounds of nitrogen and/or phosphorus, resulting in eutrophication. They and their catchments require more stringent treatment to eliminate nutrients before the wastewater is discharged for agglomerations of more than 10 000 p.e.

Compliance with the requirements of the UWWTD is assessed at the national level as well as at the level of the individual agglomeration. An agglomeration is considered to be in compliance with the UWWTD if it collects all the wastewater it generated and sends it to treatment plants, and all the plants serving the agglomeration comply with the required treatment (treatment type and discharge wastewater concentrations or percentage reduction). However, the EC allows a certain margin of flexibility to Member States when assessing compliance with Article 3 (2 % of the generated load or 2 000 p.e.), Article 4 and Article 5 (1 % of the collected load or 2 000 p.e.).

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A3.2      European results and trend in compliance

European results

The eighth report on implementation of the UWWTD (EC, 2016) assessed the situation in about 19 000 towns and cities (agglomerations) of more than 2 000 inhabitants (generating pollution corresponding to a population of 495 million) during 2011 or 2012 (EC, 2015).

Almost 15 000 towns and cities, or 86 % of the pollution load, are in the 15 Member States that joined the EU before 2004 (EU-15). The remainder are in the 13 Member States that joined the EU in 2004, 2007 and 2014 (EU-13). The compliance assessment was carried out for 25 Member States. Data from Italy and Poland were of insufficient quality to include, while for Croatia no compliance obligation was applicable as of 2012.

Figure A3.1 presents the status of the implementation of the UWWTD across the EU for the reference year (2011 or 2012). It shows the share of the total generated load that requires compliance with the UWWTD (darker bars) and the share of the load for which compliance has been achieved (paler bars), both in relation to the total generated load.

Summarising the results, we can conclude that the obligations for collecting sewage (Article 3) were met for 94.9 % of the total generated load. This corresponds to 479 million p.e. and 98.3 % of the load that had to be collected (only 96.4 % of the total generated load had to be collected).

Article 4 deals with biological (or ‘secondary’) treatment. These obligations were met for 464 million p.e. and 92.0 % of the load that had to be treated (93.5 % of the total generated load required biological treatment).

Article 5 requires more stringent treatment in sensitive areas with agglomerations over 10 000 p.e. These obligations were met for 285 million p.e. and 88.1 % of the load that needed more stringent treatment (57.5 % of the total generated load was identified as needing this level of treatment).

Compliance rates in the EU-15 are, in general, very high. They are lower in the EU-13, especially in sensitive areas (Article 5). Results for the EU-28 overall, however, are still very high because the EU-13 contributed relatively little pollution (14 %).

  

Figure A3.1 Average compliance rates in relation to the total generated load.

Note: darker bars indicate load that should be collected and/or treated; paler bars indicate load for which the collection or treatment provided complies with the provisions in the directive. Data exclude Poland, Italy and Croatia.

Article 3: wastewater collection from agglomerations of more than 2 000 p.e.

Article 4: wastewater with biological treatment.

Article 5: wastewater with more stringent treatment in sensitive areas.

Mpe: million p.e.

Source: EC (2015a).

Trends in compliance

The EC publishes regular implementation reports. Comparing the compliance rates in them, a positive pattern appears: compliance increases over time (Table A3.1).

Table A3.1 European compliance rates for Articles 3, 4 and 5

Report

Reference year

Compliance rate (%)

Collection

Biological treatment

Advanced treatment

2

1998

9

3

2000/2001

83

69

14

4

2001/2002

79

84

5

2005/2006

99

86

85

6

2007/2008

93

78

75

7

2009/2010

94

82

77

8

2011/2012

98

92

88

Note: Nine EU Member States (Bulgaria, Czech Republic, Greece, Ireland, Italy, Malta, Poland, Spain, United Kingdom) are missing from the presentation of the fifth report. The sixth report does not include a dataset for the United Kingdom and the eighth report does not include data for Italy and Poland.

Source: EC 2002-2013

UWWTP indicator: proportion of inhabitants connected to UWWTPs during last 20 years

The percentage of the population connected to primary, secondary and more stringent wastewater treatment in southern, south-eastern and eastern Europe has increased over the last 10 years. The latest proportions of the population connected to wastewater treatment in the southern countries are comparable to those in the central and northern countries, whereas those in eastern and south-eastern Europe are still relatively low.. The percentage of more stringent, also called tertiary treatment is far lower in the southern than in the northern countries. This is also the case in central Europe, where the overall treatment level is fairly high. In eastern and south-eastern Europe, the total number of the population connected to wastewater treatment has increased over the last two years, but the proportion of untreated wastewater is still relatively high. In the non-EU western Balkan countries, an increasing proportion of wastewater is treated, but still most of it is not (Figure A3.2).

Figure A3.2 Changes in wastewater treatment in regions of Europe between 1990 and 2012.

Note: North: Finland, Iceland, Norway, Sweden. Central: Austria, Denmark, England and Wales, Scotland, Germany, Ireland, Luxembourg, Netherlands, Switzerland. South: Cyprus, France, Greece, Malta, Portugal, Spain. East: Czech Republic, Estonia, Hungary, Latvia, Lithuania, Poland, Slovakia, Slovenia. South-east: Bulgaria, Romania, Turkey. West Balkan: Albania, Bosnia and Herzegovina, Macedonia (FYR), Serbia.

Only countries with data from (almost) all periods included (number of countries in parentheses).

The chart is based on the Eurostat data set, which includes information on all wastewater treatment plants reported, regardless of the size of agglomeration they serve. Thus the number may differ (in some countries) from the numbers of wastewater treatment plants reported under the UWWTD, which reports only those serving agglomerations of more than 2 000 p.e.

Source: EEA, Urban Waste Water Treatment Indicator (CSI 024, last update 2015), http://www.eea.europa.eu/data-and-maps/indicators/urban-waste-water-treatment/urban-waste-water-treatment-assessment-3.

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A3.3      Country comparison

For more stringent treatment (removal of nutrients in sensitive areas), the overall compliance rate was 88 %. However, EU-13 Member States showed delays in implementing more stringent treatment. They treated only 32 % of wastewaters appropriately. On the positive side, 11 countries reached 90–100 % compliance.

The maps in Figure A3.3 show compliance rates for collecting systems (Article 3), secondary treatment (Article 4) and more stringent treatment (Article 5) in Member States as a percentage of the load subject to compliance (reference years 2011–2012).

For Article 3 (collecting systems), 20 EU Member States are completely compliant: they collect 100 % of the wastewater load. Belgium has a compliance rate of 98 %, Estonia 94 % and Romania 99 %. Only two EU Member States collect less than 60 % of the load that should be collected (Bulgaria 12 % and Slovenia 57 %).

For Article 4 (secondary treatment), 16 EU Member States reach a level of compliance between 90 % and 100 %. Five (Cyprus, the Czech Republic, , France, Portugal and Spain) have a compliance rate between 60 % and 90 %. Romania’s is 48 %. Low compliance rates can be seen in Bulgaria (11 %) and Slovenia (14 %). Malta shows no compliance with Article 4.

More stringent treatment of wastewaters, also known as tertiary treatment, complements secondary treatment when needed. It mostly aims to eliminate nutrients to combat eutrophication. An additional benefit is increasing the removal rates of hazardous substances. More advanced treatment includes sand filtration, ozonation and ultraviolet (UV) treatment, which are well-known treatment technologies for drinking water. Several treatment plants have installed these measures to reduce bacteriological pollution that might affect human health (e.g. for drinking water zones or bathing waters) and at the same time to further reduce emissions of hazardous substances. Other more stringent treatment technologies are chlorination and membrane technologies. All of the above are widely discussed as ways of reducing the micropollutants (emerging contaminants, including pharmaceuticals, personal care products and industrial chemicals) entering the aquatic environment.

Compliance with Article 5 (more stringent treatment) is between 90 % and 100 % in 10 EU Member States. Five Member States (Belgium, Estonia, Hungary, Portugal and Sweden) show compliance rates of 60 % to 90 %. On the other hand, 10 Member States are still below 50 % compliance; of these, Latvia and Malta have 0 % compliance with Article 5 and Bulgaria and Ireland show 1 % compliance. However, many countries increased their level of compliance in recent years.

Figure A3.3 Share of generated load compliant with Articles 3, 4 and 5 in the EU-28.

  

Source: EC (2016).

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A3.4      Measures to improve treatment

The UWWTD sets minimum requirements for wastewater treatment in agglomerations of more than 2 000 p.e. However, other drivers (e.g. the WFD, other water directives, water utilities benchmarking, Wastewater discharge licence based on more stringent limits than set in the Directive, wastewater reuse) encourage ‘better treatment’ (i.e. more efficient, more stringent or addressing hazardous substances).

Optimisation of the performance of wastewater management systems improves the cost-effectiveness of wastewater treatment. Practical solutions include measures based on advanced knowledge of microbial systems (sequential batch reactors, biological filters, membrane bioreactors) and/or using integrated plant-wide control systems. However there can also be a need to increase the proportion of wastewater receiving treatment. Introducing measures to control the discharge of untreated wastewater from CSOs; maintaining the hydraulic capacity of existing infrastructure; providing suitable retention facilities or introducing decision support systems; are ways to improve quality of final discharge.

Several Member States have achieved the maximum level of compliance with Articles 3, 4 and/or 5 in recent years. However, not content with that, they are regularly improving wastewater treatment by advancing it further, improving the maintenance and technical equipment of UWWTPs, etc.

Agglomerations of more than 10 000 p.e. in sensitive areas must remove nutrients. Figure A3.4 shows that nutrient removal is quite common in agglomerations smaller than 10 000 p.e. in Austria, Finland and the United Kingdom.

Figure A3.4 More stringent treatment.

Austria (2010)

Finland (2009)                         

                            
United Kingdom (2010)
                                             

Source: EEA, DISCOMap, UrbanWasteWater, http://discomap.eea.europa.eu/Services.aspx?agsID=14&fID=5549.

Other measures that go beyond the requirements of the UWWTD are establishing appropriate wastewater collection and treatment in agglomerations smaller than 2 000 p.e. This is particularly the case if they are located in protected areas, or if the discharge affects the status of water bodies.

The hygiene standards for bathing water, and the more stringent limits related to wastewater reuse, encourage additional treatment methods such as disinfection, chlorination and ozonisation. The Urban Waste Water Treatment Maps (http://www.eea.europa.eu/data-and-maps/uwwtd/interactive-maps/urban-waste-water-treatment-maps-1) provide an overview of their use across the EU, in the layer ‘types of additional polishing treatment steps’. A total of 25 807 treatment plants were reported under the UWWTD in 2013. Of them, 778 use UV disinfection, 41 use ozonation and almost 4 000 use chlorination to remove or eliminate pathogens.

Newly identified, potential pollutants can be termed ‘emerging contaminants’. This group now includes certain pharmaceuticals and personal care products. Studies from numerous European wastewater treatment plants have found such emerging contaminants in the treated wastewater. Technologies such as flocculation, ozonation, advanced oxidation, membrane filtration (activated carbon adsorption) and photocatalysis could help remove trace amounts of contaminants from wastewater effluents (Gadipelly et al., 2014; Castiglioni et al., 2006). Increasingly, countries go beyond the requirements of the UWWTD in their efforts to improve water quality under the WFD.

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A3.5      Information dissemination

Every two years, the relevant authorities publish situation reports on the disposal of urban wastewater and sludge in their areas. The principal aim of these reports is to inform the public regularly of the situation, on a given date, regarding wastewater collection and treatment. They also show how the situation has developed since at least the two previous years.

At regular intervals, the EC also draws up implementation reports on the situation of wastewater treatment and the progress of implementing the UWWTD in the EU. Since 2007, reporting under Article 15 of the UWWTD has followed a new standardised approach. The EC, the EEA and Member States developed it jointly and set it up in line with reporting principles under the Water Information System for Europe (WISE).

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