EU policy on sewage sludge utilization and perspectives on new approaches of sludge management

Abstract

This paper presents the current sewage sludge legislation in Europe and expected developments regarding the coming directives on the application of the "End-of-waste" criteria and on fertilizers. Discussion on sludge production and processing is also included. The Directive 86/278 has regulated the use in agriculture of residual sludge from domestic and urban wastewater. After 1986, this directive was transposed in the different member state legislation and currently the national limit values on heavy metals, some organic micropollutants and pathogens are placed in a rather wide range. This seems the inevitable consequence of different attitudes towards sludge management practices in the member states. The discussion by the European Joint Research Center (JRC) in Seville regarding application of end-of-waste criteria for compost and digestate has produced a final document (IPTS 2014) where sludge was excluded from the organic wastes admitted for producing an end-of-waste compost. Sludge processing in Europe seems addressed to different goals: sludge minimization, full stabilization and hygienization by thermal hydrolysis processes before anaerobic digestion, and on-site incineration by fluidized bed furnace. Thermophilic anaerobic digestion was applied with success on the Prague WWTP with a preliminary lysimeter centrifugation. Coming techniques, like wet oxidation and pyrolysis, are applied only on very few plants.

Sustainable Management of Sewage Sludge for the Production of Organo-Mineral Fertilizers

“…During the technological process 50-70% of Cd and 70-97% of Cr pass to the acid from phosphate ores. In addition, Fe, Al, Zn, Cu, V, U and As [22] exhibit a high degree of leaching. As WPPA is generally used for inorganic fertilizers, it is necessary to select resources with low contaminants content in order to reduce the introduction of heavy metals to fertilizers.…”

“…Such countries as the USA, Canada and the UK claim that there is no need for setting limit values on emerging organic pollutants because their typical concentration in sewage sludge cannot pose a threat for environment and human health. However Germany, Sweden, Denmark, France, the Czech Republic and Hungary fixed allowable concentration of toxic organic compounds (PAH, PCB, dioxins, DEHP, alkyl sulphonates, nonylphenol) in sewage sludge [22]. The share of organic pollutants depends on a source of waste water and type of treatment to which sewage sludge was subjected [23].…”

Changes in Phytotoxicity during High-rate Anaerobic Digestion and Sequential Aerobic Composting for Sewage Sludge Stabilization

“…The anaerobic digested and compost sludge were considered to have a high potential fertilizer value by their contents of N, P, K and micronutrients [2]. Thus, land application is an important disposal route and now it's the trend not only in European countries but also in China [3,4]. However, parameters as electrical conductivity, ammonium nitrogen and the behavior of heavy metals in sludge are among the factors of phytotoxicity which limit sludge application in soil [2,5,7].…”

Effect of copper and zinc on microbial tolerance to triclosan in two soil types

“…In order to beneficially re-use sewage sludge and biosolids while protecting human health and the environment, various guidelines for the safe application of sewage sludge and biosolids to land have been released around the world (Department of Environment UK 1989;New Zealand Water and Wastes Association 2003;Mininni et al 2015). Such guidelines regulate the application of sewage sludge, biosolids and sewage sludge compost to land based on the concentration of residual heavy metals, nutrients, pathogens and some selected organic micropollutants (Department of Environment UK 1989;New Zealand Water and Wastes Association 2003;Mininni et al 2015).…”

“…Such guidelines regulate the application of sewage sludge, biosolids and sewage sludge compost to land based on the concentration of residual heavy metals, nutrients, pathogens and some selected organic micropollutants (Department of Environment UK 1989;New Zealand Water and Wastes Association 2003;Mininni et al 2015). However, to the best of our knowledge and that of Bedoux et al (2012), there is no regulation or guideline value for the concentration of triclosan in sewage sludge or biosolids being applied to land.…”