直到20世紀90年代，技術一直是處理廢物和殘留物的主要動力，目標是處理(垃圾填埋)處理、儲存和在某些情況下分類的廢物。在1990年代，原材料的耗竭和社會經濟問題支持了廢物和殘渣的直接回收。然而，當廢物/殘余物含有大量污染物，例如重金屬和有機化合物(VOC、PAH)，以及當去除/穩定或破壞污染物的處理過程產生排放時，直接回收方法是有限的。由于自然資源的耗竭、溫室氣體排放量的增加以及對安全回收廢物和生物量方面的可持續發展的需要的認識，將廢物/生物量轉變為有價值的材料和能源(即價值化)正成為一個強有力的趨勢。

Until the 1990s, technology was the main driver when dealing with waste and residues, the objective being the treatment of waste for (landfill) disposal, storage, and in some cases sorting. In the 1990s, depletion of raw materials and socio-economical concerns supported the direct recycling of waste and residues. However, the direct recycling approach is limited when waste/residues contain significant amounts of pollutants such as heavy metals and organics (VOC, PAH), and when the treatment process to remove/stabilize or destruct the pollutant generates emissions. Due to depletion of natural resources, increasing greenhouse emissions, and awareness of the need for sustainable development in terms of safely reusing waste and biomass, the transformation of waste/biomass to valuable materials and energy (i.e. valorization) is emerging as a strong trend.