Recovery and recycling

The concept of defining waste as secondary raw materials, and the return of these into the economic cycle according to their valuable properties, are pivotal for increased resource efficiency.  The modern circular economy approach pursues these ideas as the primary goal. For this purpose, quality and material specifications of primary and secondary raw materials have to be mostly equal. These requirements determine the selection of appropriate processing and preparation methodology and strategies. Ultimately, waste management efforts have to focus on the matter of sorting arising waste materials at the site of origin into different material classes. Viable sorting systems have been established for a range of waste materials, e.g. waste paper. However, there is a distinct lack of sustainable sorting and processing procedures for other waste materials. The fact that material recovery plays a vital role in climate protection efforts has been largely ignored to date. The burdens associated with primary raw material production exceed the actual energy content.


Benedikt Kauertz

Dipl. Ing. Spatial and Environmental Planning
Scientific Director
+49 (0)6221 4767 57

Selected waste materials in focus

  • Sewage Sludge

    The valuable properties of sewage sludge are defined by organic energy and nutrient content, especially phosphorus (phosphorus recovery). However, sewage sludge is highly contaminated with organic pollutants and heavy metals at the same time. Common recovery pathways include agricultural distribution, mono-incineration in fluidised bed furnaces, or the co-incineration in coal or cement plants. Sewage sludge recovery is subject to ongoing debate. Direct application for agricultural use is less and less common due to considerably increased associated soil pollution. Stricter regulations and limits in the sewage sludge legislation amendment and the fertiliser ordinance could spell the end of agricultural application for most sewage sludge. ifeu has been exploring environmental aspects of solutions for sewage sludge treatment in a range of projects for a number of years.


  • Waste oil

    The environmental best-practice recovery of waste oil has been subject to intense fundamental debate for many years. According to the Waste Directive, recycling into lubricants is preferable over use as secondary fuel. Existing LCA results illustrate the  superior benefits of waste oil recycling. However, they also show relatively favourable outcomes for fuel use as a substitute for coal. The pioneering LCA work done by ifeu (left) in this context is held in high regard at all levels, including the Federal Environment Agency, the European Commission and business stakeholders. However, technology and material quality requirements in this sector are highly dynamic. The production of primary engine and transmission lubricants requires more and more complex processing and high-quality raw materials, which retain their valuable properties as waste oil recycling potentials. In addition, recycling technology is constantly advancing. Here, innovation influences environmental assessments of recycling technology and products. ifeu monitors these developments and takes care to update existing studies as appropriate. These ongoing efforts include methodology questions of cascading use and footprinting of recycling products.

  • Phosphorus

    Phosphorus as a nutrient has recently attracted considerable attention. The phosphorus loop is very open, yet phosphorus is a finite resource and major deposits are often located in volatile regions with unstable political systems. The phosphorus content of sewage sludge would be sufficient to cover about 40% of mineral phosphorus demand in Germany. Thermal sewage sludge recovery—whether via mono-incineration or co-incineration—is always associated with nutrient loss. Meanwhile, a range of phosphorus recovery methods seamlessly integrated into the sewage sludge treatment chain are available. High-yield processes for the extraction of phosphorus from ash require mono-incineration. Additional phosphorus sources may be found in landfills, primarily for the deposition of sewage sludge and sewage sludge ash. A number of products also contain phosphorus that could be conserved. Ifeu has been exploring the environmental aspects of phosphor recovery and conservation in a number of projects.


  • Plastics

    Conventional plastics are made from mineral oil, a finite resource and energy carrier. Their incineration releases carbon in the form of fossil carbon dioxide, thus feeding and exacerbating the greenhouse effect. Moreover, the production of primary plastics is complex and energy-intensive. In consequence, material use of plastics is paramount. To date, successful recovery often fails due to lack of expertise of the recovery industry, which is frequently unaware of the material properties that other branches of industry seek in their feedstocks. ifeu examines framework conditions for increased material use of plastics in a number of projects.



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