3.1.1 Point source pollution (urban waste water, industry)

3.1.1 Point source pollution (urban waste water, industry)


Point source pollution to surface waters relates mostly to discharges from urban waste water including storm overflows, industrial sites or to a much lesser extent to aquaculture. Groundwater is mainly affected by leaching of hazardous substances from landfills and contaminated sites (EEA 2018b).

In Europe, point source pollution discharges have markedly decreased over the last decades caused by improved purification of urban waste water and reduced industrial discharges. Nevertheless, point source pollution still results in water pollution by oxygen consuming substances, nutrients, and hazardous substances with high impacts on aquatic ecosystems and human health. 

According to the 2nd RBMPs, 15 % of all surface water bodies are affected by point source pollution, from which two-thirds are assigned to urban waste water from treatment plants and some 20 % to industrial waste water ([1]). For groundwater, significant point source pressures are present in 14 % of the area mainly from contaminated sites, industrial sites, waste disposal sites, mining areas, and urban waste water (EEA 2018b).

More than 30 000 industrial and urban waste water facilities in Europe discharge more than 40 000 million m³ waste water every year (EC, n.d.; Van den Roovaart, et al., 2017). Three quarters of them treat water from urban sewage systems with a size of agglomeration of more than 2 000 population equivalents (EC 2019a). 90 % of the population in EU Member States are connected to sewage systems. The highest rates of above 80 % are located in Central and Northern Europe, where also the best level of treatment (e.g. nutrient removal) has been implemented in the majority of waste water treatment plants([2]).

Waste water from industry has decreased over the last decade. This is caused by increased regulations (e.g. Industry Emissions Directive – IED or the European Pollutant Release and Transfer Register -  E-PRTR), improvements in treatment and implementation of best available techniques reference documents, e.g. BREF ([3]). Furthermore, relocation of various heavy polluting and energy intensive manufacturing industries outside Europe has also led to water quality improvement ([4]). The connection of industrial waste water to urban waste water treatment plants to avoid direct industrial emissions to water has marginally increased (EEA 2019a). Industries with still high direct releases to water are e.g. pulp and paper, steel, energy supply or chemicals, whereas manufacturing or food production tend to be more connected to urban waste water treatment plants (EEA 2019a). This is also due to the recommendation of the best available technique reference document for industrial installations (Canova, et al., 2018).

Also, storm water causes problems dependent on the sewer system. In case of heavy rains, overflows from combined sewer systems are discharged into surface waters with a mixture of rainwater and untreated waste water. This can lead to a temporally high pollution pressure.

([1]) Source: https://www.eea.europa.eu/themes/water/european-waters/water-quality-and-water-assessment/water-assessments/pressures-and-impacts-of-water-bodies; download 17.04.2020

([2]) Source: https://www.eea.europa.eu/data-and-maps/indicators/urban-waste-water-treatment/urban-waste-water-treatment-assessment-4

([3]) https://eippcb.jrc.ec.europa.eu/reference/

([4]) Source: https://www.eea.europa.eu/data-and-maps/indicators/industrial-pollution-in-europe-3/assessment

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Impacts from point source pollution to waters are caused by oxygen consuming substances, like ammonium or other substances, indicated by the measurement of the biological oxygen demand (BOD), nutrients such as phosphorus and nitrogen, hazardous substances, emerging pollutants, pathogens, like bacteria, viruses, or parasites, and microplastic particles.

The BOD shows how much dissolved oxygen is needed for microorganisms to decompose the organic matter. The resulting oxygen deficit in highly organic polluted waters causes impacts on aquatic communities, e.g. the loss of several macroinvertebrates and acute toxic impacts on fish.

Overall, concentrations of oxygen consuming substances (BOD, ammonium) and nutrients (nitrate and phosphate) have decreased over the last 25 years (Figure 3). It needs to be mentioned, that nitrate as well as phosphorus in rivers is not solely attributable to point sources of pollution. Those substances can also be released from diffuse sources, like agriculture. 

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Figure 3             Trends in biological oxygen demand (BOD), ammonium, orthophosphate and nitrates in rivers

Notes: Insert notes here

Source: (EEA 2019b)

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Hazardous substances are defined as toxic, persistent, and liable to bio-accumulate (Article 2, WFD). Some of the priority substances listed in Annex X of the WFD are defined as hazardous, for which all discharges, emissions and losses must be ceased within 20 years after adoption of cessation proposals by the European Parliament and the Council (WFD, Art. 16 (6)). Those substances are for example 4-Nonylphenol (surfactant) or pBDEs (flame retardants) used in many industrial productions.  Beside the risk of hazardous substances, emerging pollutants are present in low concentrations and include inter alia pharmaceuticals and personal care products, chemical degradation products, or endocrine‑disrupting compounds.

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Measures and management challenges

Due to the successful implementation of the Urban Waste Water Treatment Directive (UWWTD), point source pollution pressure from urban waste water has significantly decreased. This is the result of the improved rate of population connected to sewage systems, but also the implementation of second (biodegradation) and third (nutrient removal) treatment levels all over Europe ([5]).

Measures to further reduce point source pollution from urban waste water but also industry include e.g. construction and adaptation, expansion, optimization of existing treatment plants, connection of households to sewer systems or consolidation and closure of non-effective treatment plants.

Improved efforts to retain chemicals in waste water treatment plants should go hand in hand with clear efforts to reduce them at source. Such measures can range from raising consumer awareness, to encouraging industries to adjust the composition of their products, to, over the longer term, fundamentally reviewing our use of chemicals and product design.

One example of source-based measures is the ban of phosphates in consumer detergents to avoid eutrophication in surface waters. The remaining allowed use of phosphates was legally fixed in Regulation 648/2004/EC (EU 2004). The European Parliament proposed a ban of the use of phosphates in consumer laundry detergents as of 30 June 2013 with similar restrictions to automatic dishwasher detergents for consumers as of 1 January 2017 ([6]).  

Furthermore, measures can be assigned to stricter requirements like lower targets for concentrations of specific pollutants in the discharged waste water by the responsible authority. This has been applied to protect drinking water resources of Lake Constance, the biggest lake in Germany. All treatment plants at the tributaries of the lake reduced markedly their phosphorous concentrations in the waste water discharge. Till today, Lake Constance is at good ecological status with drinking water quality (International Commission for water protection of Lake Constance (IGKB), 2014).

Even though considerable success has been achieved to reduce the discharge of pollutants from point sources, more emphasis is needed to protect water quality and human health. Despite varying conditions such as the density of population in European countries, or economic background, treatment has to be further improved in eastern parts of Europe in particular. A lower storm overflow is necessary with the help of nature-based solutions. To increase treatment, the implementation of the fourth treatment level is in progress. This level consists of innovative treatment techniques (e.g. oxidation with ozone, activated carbon filtration, membrane filtration) (UBA, 2014, EEA, 2019c). For example, by 2040, 100 of the 700 wastewater treatment plants in Switzerland will be equipped with a fourth purification level after decision in a plebiscite ([7]). The investment requirement of CHF 1.2 billion will be financed through a nationwide wastewater tax, which is a maximum of CHF 9 per inhabitant and year ([8]).

Furthermore, increasing energy costs, the reuse of high quality waste water and recycling of raw materials to circular economy as well as the consideration of climate change will be challenging tasks for the future (EEA, 2019).

([5]) Source: Source: https://www.eea.europa.eu/data-and-maps/daviz/changes-in-wastewater-treatment-in-8

([6]) Source: https://ec.europa.eu/commission/presscorner/detail/en/IP_11_1542

([7]) Source: https://www.vdi-nachrichten.com/technik/die-vierte-reinigungsstufe/

([8]) Source: https://www.vdi-nachrichten.com/technik/die-vierte-reinigungsstufe/

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