The treatment of urban waste water from our homes and workplaces is fundamental to ensuring public health and environmental quality. The main objective of the Urban Waste Water Treatment (UWWT) Directive (91/271/EEC), and equivalent national legislation for non-EU countries, is to protect surface waters from the adverse effects of waste water discharges, such as organic pollution, the associated development of bacteria and fungi, and oxygen depletion, which degrade aquatic life. This is achieved through the collection and treatment of waste water in settlements and areas of economic activity (agglomerations) with a population equivalent (p.e.) of more than 2 000. In most cases, the UWWT Directive stipulates that waste water must be subject to biological treatment (secondary treatment), but in catchments with particularly sensitive waters, such as those suffering from eutrophication, more stringent tertiary waste water treatment may be required to substantially reduce nitrogen and phosphorus pollution.
The installation of waste water treatment facilities first requires the set-up of a sewage collection system and then the provision of facilities to treat the collected waste water. Where there is a low proportion of a population connected to waste water treatment facilities, it may be due to a lack of financial resources (or priority) for providing the sanitation services or to a high proportion of the population living outside agglomerations. In the latter case, where people live in scattered communities, individual sanitation systems may be the most feasible solution. Such systems may provide treatment efficiencies that are similar to those of larger urban waste water treatment plants.
The indicators used in this assessment to measure discharged loads of organic matter and nutrients from urban waste water treatment plants to European surface waters are:
The percentage of the national population connected to urban waste water treatment facilities
In central European countries, there was a high overall urban waste water treatment connection rate, of 97 % (Austria, Belgium, Denmark, Germany, Luxembourg, Netherlands, Switzerland and United Kingdom). The rate is slightly lower in northern countries, at 86 % (Finland, Iceland, Norway and Sweden).
The connection rates in eastern, southern and south-eastern countries are similar:
75 % of the population in eastern European countries (Czech Republic, Estonia, Hungary, Latvia, Lithuania, Poland and Slovenia);
77 % of the population in southern European countries (Greece, Italy, Malta and Spain);
78 % of the population in south-eastern countries (Bulgaria, Romania and Turkey).
The percentage of the national population connected to tertiary urban waste water treatment facilities
More than 77 % of the population of northern and central Europe is connected to an urban waste water treatment plant that implements tertiary treatment, preventing significant amounts of nutrients and organic matter from reaching surface waters. Waste water generated by more than half of the population in southern and by over 60 % of the population in eastern Europe receives tertiary treatment. In central and southern countries, this percentage increased between 1995 and 2015 (from 47 % to 80 % in central Europe, and from 15 % to 53 % in southern Europe), while for eastern countries the percentage increased from 36 % to 61% between 2005 and 2015. In south-eastern Europe, the percentage of the population connected to treatment plants with tertiary treatment is lower, at about 20 % (an increase from 7 % in 2005), with 23 % of the population in this region being connected to secondary treatment.
Figure 1. Changes in urban wastewater treatment
Figure 2. Type of waste water treatment in ‘big cities’ (agglomerations of more than 150 000 p.e.) in the EU (Countries included in this assessment are Austria, Belgium, Cyprus, Czech Republic, Germany, Denmark, Estonia, Spain, Finland, France, Greece, Italy, Lithuania, Luxembourg, Latvia, Netherlands, Portugal, Romania, Sweden, Slovenia, Slovakia and the United Kingdom.)
Specific regional assessment
Northern Europe: the connection rate is between about 80 and 90 % in Finland, Iceland, Norway and Sweden. In the cases of Finland and Sweden, treatment is almost entirely at the tertiary level. In Norway, about 20 % of connected urban waste water receives primary treatment only, while in Iceland the majority of the collected urban waste water either receives primary treatment only or is not treated. The trends in the rate of the national population connected to urban waste water treatment plants appear stable, with slight increases in the proportion receiving tertiary treatment in Norway being the main change in recent years.
Central Europe: countries in central Europe have some of the highest overall connection rates in Europe — more than 90 % of the population connected in all countries other than Ireland. The proportion of the population connected to tertiary treatment ranges from 80 to 99 % in Austria, Denmark, Germany, the Netherlands and Switzerland. Tertiary treatment connection rates among this group of countries were lowest for Ireland (18 % of the population connected to tertiary treatment).
Southern Europe: the overall percentage of the population connected to urban waste water treatment ranges from 30 to 99 %. The rate is above 90 % in Greece, Malta and Spain. Tertiary treatment is most prevalent in Greece (89 %), followed by France and Spain, with 60-70 % of the urban waste water receiving this high level of treatment. There was a significant upgrade in treatment facilities in these countries between 2005 and 2010. In Cyprus, Malta and Portugal, the percentage of the population connected to tertiary treatment is below 20 %. Moreover, Portugal reported that over 10 % of the population is connected to collecting systems without treatment.
Eastern Europe: the overall proportion of the population connected to urban waste water treatment ranged from 70 to 85 % (with the exception of Slovakia) in 2015. Over 70 % of the population in the Czech Republic and Estonia is connected to tertiary treatment, while Hungary, Lithuania and Poland reported a tertiary treatment connection rate of 59-65 %. In Latvia, the rate of connection to tertiary treatment is lower, at about 17 %, and in Slovenia, about 27 % of the population is connected to tertiary treatment. Slovakia reported that 65% of the population was connected to urban waste water collecting and treatment systems in 2015.
South-eastern Europe: the percentage of the population connected to urban waste water treatment plants ranges from 48 to 87 %. In Bulgaria and Romania, about half of the treatment is tertiary, while in Croatia and Turkey primary or secondary treatment prevails. Just under a quarter of the population of Turkey is connected to collecting systems without treatment, but there has been steady progress in treatment availability and the level of treatment since 1995. While there was a significant increase in treatment availability in Croatia between 2005 and 2012, there has been limited progress in connecting populations to wastewater treatment in Bulgaria and Romania since 2005.
Western Balkans: where it is collected in the Western Balkans, urban waste water is mainly collected without treatment. The overall percentage of the population connected to urban waste water treatment plants ranges from 35 to 59 %, although most of this urban waste water is not treated. In Albania, all the waste water collected receives some level of treatment, with about half receiving tertiary treatment.