1. Council Directive 91/271/EEC of 21 May 1991 concerning urban waste water treatment. Off J L 135, 30/05/1991, pp 40–52
2. Draft discussion document for the ad hoc meeting on biowastes and sludges 15–16 January 2004, Brussels
3. Council Directive 86/278/EEC of 12 June 1986 on the protection of the environment, and in particular of the soil, when sewage sludge is used in agriculture. Off J L 181, 04/07/1986 P. 0006–0012
4. Real Decreto1310/1990, de 29 de octubre, por el que se regula la utilización de los lodos de depuración en el sector agrario. Span Off Bull. 262:32339–32340
5. EC, Working Document on Sludge, 3rd Draft. 27 April 2000, ENV.E.3/LM, European Union, Brussels, Belgium