EU rules promote the use of sewage sludge in agriculture, but regulate its use to prevent harmful effects on soil, vegetation, animals and people.
Sewage sludge is a mud-like residue resulting from wastewater treatment. Sewage sludge contains heavy metals and pathogens such as viruses and bacteria.
It also contains valuable organic matter and nutrients such as nitrogen and phosphorus, and can therefore be very useful as a fertilizer or soil improver.
The quantity of sewage sludge requiring disposal in the EU is increasing, mainly due to the progressive implementation of the Directive on the treatment of urban wastewater.
EU rules on sewage sludge consider the nutrient needs of plants and ensure that the quality of soil, the surface and ground water is not impaired. It covers
- how farmers can use sewage sludge as a fertiliser
- the sampling and analysis of sludge and soils
- keeping detailed records for sludge quantities produced and used in agriculture
- the type of treatment and sites where sludge is used
- sludge composition and properties
Normally, sludge must be treated to reduce its fermentability and the health risks resulting from its use. In some EU countries, untreated sludge can be used in farming if it is injected or worked into the soil. In certain cases, sludge cannot be used at all. This includes
- on soil in which fruit and vegetable crops are grown, except for fruit trees
- on grassland or forage land that will be grazed by animals or harvested in the next three weeks
less than ten months before fruit and vegetable crops are to be harvested, when the crops are in direct contact with the soil and eaten raw
The aims of the Sewage Sludge Directive are
- to protect humans, animals, plants and the environment by ensuring that heavy metals in soil and sludge do not exceed set limits
- to increase the amount of sewage sludge used in agriculture
The Directive also
- sets limits for the concentration of seven heavy metals in sewage sludge intended for agricultural use and in sludge-treated soils (cadmium, copper, nickel, lead, zinc, mercury, chromium)
- bans the use of sewage sludge that results in concentrations of these heavy metals in soil exceeding these limit values
EU countries must send reports on the implementation of the Sewage Sludge Directive to the European Commission every three years.
Note: requested previous Irish reports to Commission on Sewage Sludge Directive from