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Sewage Sludge

sludge spreadingsludgeIntroduction

Sludge originates from the process of treatment of waste water. Due to the physical-chemical processes involved in the treatment, the sludge tends to concentrate heavy metals and poorly biodegradable trace organic compounds as well as potentially pathogenic organisms (viruses, bacteria etc) present in waste waters. Sludge is, however, rich in nutrients such as nitrogen and phosphorous and contains valuable organic matter that is useful when soils are depleted or subject to erosion. The organic matter and nutrients are the two main elements that make the spreading of this kind of waste on land as a fertiliser or an organic soil improver suitable.

The progressive implementation of the Urban Waste Water Treatment Directive 91/271/EEC in all Member States is increasing the quantities of sewage sludge requiring disposal. This increase is mainly due to the practical implementation of the Directive as well as the slow but constant rise in the number of households connected to sewers and the increase in the level of treatment (up to tertiary treatment with removal of nutrients in some Member States). The Directive sets the following targets for secondary treatment of waste waters coming from agglomerations:

  • at the latest by 31 December 2000 for agglomerations of more than 15,000 p.e. (population equivalent);
  • at the latest by 31 December 2005 for agglomerations between 10,000 and 15,000 p.e.;
  • at the latest by 31 December 2005 for agglomerations of between 2,000 and 10,000 p.e. discharging to fresh waters and estuaries.

There are more stringent provisions for agglomerations discharging into sensitive areas such as fresh waters or estuaries. The UWWTD has recently been evaluated. The European Commission will now carry out an impact assessment to assess options to revise the Directive and thus address the shortcomings identified in the Evaluation.

The Sewage Sludge Directive 86/278/EEC seeks to encourage the use of sewage sludge in agriculture and to regulate its use in such a way as to prevent harmful effects on soil, vegetation, animals and man. To this end, it prohibits the use of untreated sludge on agricultural land unless it is injected or incorporated into the soil. Treated sludge is defined as having undergone "biological, chemical or heat treatment, long-term storage or any other appropriate process so as significantly to reduce its fermentability and the health hazards resulting from its use". To provide protection against potential health risks from residual pathogens, sludge must not be applied to soil in which fruit and vegetable crops are growing or grown, or less than ten months before fruit and vegetable crops are to be harvested. Grazing animals must not be allowed access to grassland or forage land less than three weeks after the application of sludge. The Directive also requires that sludge should be used in such a way that account is taken of the nutrient requirements of plants and that the quality of the soil and of the surface and groundwater is not impaired.

The Directive specifies rules for the sampling and analysis of sludges and soils. It sets out requirements for the keeping of detailed records of the quantities of sludge produced, the quantities used in agriculture, the composition and properties of the sludge, the type of treatment and the sites where the sludge is used. Limit values for concentrations of heavy metals in sewage sludge intended for agricultural use and in sludge-treated soils are in Annexes I A, I B and I C of the Directive.

Treating waste water generated almost 8 Mio tons of sludge in 2016 in the EU 28. The sludge destinations vary significantly between Member States; however, agriculture is the main channel for waste water sludge in most of the Member States. 4 Mio tons of sludge are used in agriculture and a significant part is incinerated (1 Mio ton) or put in landfills (0.5 Mio ton). Most countries report a large share of re-use in agriculture but the share varies significantly between countries (0-100%), some using less than 20% in agriculture while others use up to 100%.

Evaluation of the Sewage Sludge Directive

Directive 86/278/ EEC was adopted over 30 years ago with a view to encourage the application of sewage sludge in agriculture and to regulate its use, so as to present harmful effects on soil, vegetation, animals and humans.

In 2014, the Directive was evaluated as part of an "Ex-post evaluation of certain waste stream directives". Findings from the evaluation showed that the Directive has been effective in achieving its initial objectives, by increasing the amount of sludge used in agriculture and by contributing to reducing environmental harm through ensuring that heavy metals in soil and sludge do not exceed the limits set by the Directive. It also showed that the Directive has had other additional benefits over and above its stated objectives, including technological improvements to wastewater and sludge treatment, improved effluent and water quality, discouragement of disposal, increased soil organic matter and water retention, and the use of biogas from dry sludge solids for renewable energy. However, the evaluation also highlighted a number of issues and identified areas where the Directive does not fully match the needs and realities as present in the year 2014, considering that it was adopted 30 years before and was never revised.

Since then, gains in knowledge and scientific progress enabled cost-effective technological developments and the deployment of innovative and sustainable solutions that should be better considered. Additionally the impact of the changing policy landscape resulting from the first and second Circular Economy Action Plan, the Bioeconomy Strategy, the new Fertilising Products Regulation, the Farm to Fork Strategy and the EU Biodiversity Strategy for 2030 also needs to be taken into account. Therefore, a study will be launched in Q3 2020 supporting the Commission to assess the evaluation criteria of the effectiveness, efficiency, relevance, coherence and EU added-value of the SSD in all Member States, in a proportional way building on and complementing the previous evaluation results.

The results of the evaluation will inform the Commission’s decision on the need to progress with an impact assessment for a proposal to revise the Directive, as outlined in the New Circular Economy Action Plan adopted on 11 March 2020.

Background information

Technical proposals for selected new fertilising materials under the Fertilising Products Regulation (Regulation (EU) 2019/1009) -JRC 2019

The European Commission revised the EU Fertiliser Regulation ((EC) 2003/2003), expanding its scope to secondary-raw-material-based fertilising products, and resulting in the publication of the new EU Fertilising Products Regulation ((EU) 2019/1009). This report explores the technical and market conditions for a possible legal framework for the manufacturing and placing on the market of specific safe and effective fertilising products derived from biogenic wastes and other secondary raw materials.

End-of-waste criteria for biodegradable waste subjected to biological treatment (compost & digestate): Technical proposals - JRC 2014

The aim of this study was to provide the full background information and a possible technical proposal on end-of-waste criteria for biodegradable waste subject to biological treatment, in line with Article 6 of the Waste Framework Directive 2008/98/EC.

Ex-post evaluation of certain waste stream directives - BIO Intelligence Service 2014;

FATE-SEES study - JRC 2012

The Commission dedicated one of the FATE series monitoring projects (monitoring of the fate and impact of pollutants on the terrestrial/aquatic interface) to the sewage sludge in order to gather information about the presence of emerging pollutants in the sewage sludge which could contaminate terrestrial and aquatic environment when the sludge is used in agriculture. The goal of this exercise is to gain an European-wide snapshot on the occurrence and concentration levels of "classical" inorganic and organic contaminants such as heavy metals, PCBs, PCDD/Fs, and PAHs, but also on less investigated emerging compounds such as, for instance, brominated flame retardants, ingredients of personal care products, pharmaceuticals, some industrial chemicals, etc. in sewage sludge (FATE SEES) and treated bio-waste (FATE COMES).

The JRC Scientific and Policy report can be accessed here: Occurrence and levels of selected compounds in European compost samples (FATE SEES)

The DG ENV together with DG JRC organized a workshop summarizing the results of FATE-SEES component which was held in Brussels on 6 June 2012. The presentation of results was followed by presentation of some Member States experience when setting limits for contaminants in sewage sludge.

See attached presentations from the workshop:

Environmental, economic and social impacts of the use of sewage sludge on land - Milieu Ltd, WRc PLC and RPA Ltd 2010.

The Commission launched a study to gather existing information on the environmental, economic, and social as well as health impacts of present practices of sewage sludge use on land. This study also assessed the risks and opportunities that can be foreseen in coming years and identified possible options for European policy and estimated their costs and benefits. 

Studies

Publications

  • Proceedings of the Workshop on "Problems around sludge", 18-19 November 1999, Stresa (Italy)
  • Proceedings of the Workshop on "Harmonisation of sampling and analysis methods for heavy metals, organic pollutants and pathogens in soil and sludge"
    Part I
    (pdf 1,600K) 
    Part II
     (pdf 1,900K)

Legislation

Summary of EU Waste Legislation on Sewage Sludge

Past Events

Reporting

Reports on the implementation on waste legislation

For any further information or clarification, please contact: https://ec.europa.eu/environment/contact/contact_en.htm