## 4 Current Management of IBA  
Currently, waste classification as hazardous or non-hazardous in the EU is based on two documents: (i) Commission Decision 2000/532/EC on the European List of Waste (LoW), revised by EU Decision 2014/955/EU, and (ii) Annex III to Directive 2008/98/EC on waste (Waste Framework Directive--WFD), amended by Commission Regulation (EU) No 1357/2014. The ferrous materials that are generally recovered from IBA are an absolute entry of non-hazardous waste in the LoW with code 19 01 02. However, the remaining material of bottom ashes appears as a mirror entry in the LoW (codes 19 01 11* and 19 01 12), meaning that its classification relies on the evaluation of waste properties that render it hazardous according to Regulation (EU) No 1357/2014, and on the assessment of persistent organic pollutants (POP) and corresponding concentration according to Regulation \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Properties**} & \multicolumn{2}{c}{[59] a  & [60] b  & [55] d  & **SOGAMA (2019) e ** & **TIRME (2020) f ** \\ \cline{2-7}  & **Valorsul** & **LIPOR** & **LIPOR** & **ARM** & **SIRUSA** & **SOGAMA** & **TIRME** \\ \hline P\({}_{2}\)O\({}_{5}\) & 5.5 & 2.9 & 3.91 & 6.27 & 1.55 & 3.51 & 1.69 \\ MgO & 2 & 3 & 5.11 & 2.59 & 2.66 & 1.79 & 2.84 \\ K\({}_{2}\)O & 2 & 2.2 & 3.12 & 1.33 & 1.54 & 2.10 & 0.76 \\ TiO\({}_{2}\) & 0.5 & 0.7 & - & 1.29 & 0.65 & 0.42 & 0.54 \\ SO\({}_{3}\) & - & - & 2.43 & 1.55 & 2.57 & 1.20 & 3.59 \\ BaO & - & - & - & 0.12 & - & 0.12 & 0.08 \\ CuO & - & - & - & 0.2 & 0.13 & 0.16 & 0.27 \\ Cr\({}_{2}\)O\({}_{3}\) & - & - & - & 0.11 & - & 0.04 & 0.07 \\ PbO & 0.35 & - & - & 0.16 & 0.11 & 0.07 & - \\ NiO & - & - & - & 0.02 & - & 0.01 & 0.01 \\ ZnO & 0.3 & - & 0.65 & 0.33 & 0.51 & 0.20 & - \\ MnO & 0.1 & 0.1 & - & 0.09 & 0.03 & 0.04 & 0.08 \\ SrO & - & - & - & 0.05 & 0.07 & 0.07 & 0.05 \\ SnO\({}_{2}\) & - & - & - & 0.04 & 0.02 & - & 0.02 \\ ZrO\({}_{2}\) & - & - & - & 0.03 & 0.03 & 0.03 & 0.02 \\ Cl & - & - & 2.42 & 1.05 & 1.42 & 0.18 & 0.50 \\ Loss on ignition & & & & & & & \\ (1000 \({}^{\circ}\)C) & 5.5 & 7.2 & - & - & 5.8 & 1.5 & 14.8 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: _Cont._(EU) 2019/1021. As a result, there are different approaches for the management of IBA worldwide, particularly among the EU Member States [13; 15]. IBA is commonly classified as non-hazardous [59; 73; 74]. According to the Portuguese and Spanish legislation, IBA has been classified as non-hazardous waste. Given the large amounts of produced IBA, efforts have been made to valorize this material considering different applications instead of disposing of it in landfills. Indeed, IBA has the potential for the recovery of metals and minerals, enabling the saving of natural resources and it has been largely recycled in different countries. Ferrous and non-ferrous metals are usually recovered through magnetic separation and Eddy current separation techniques, respectively [42; 75]. Nearly 80% of metals can be recovered from IBA, and metals such as aluminum, copper, steel, and zinc are frequently separated and applied as secondary raw materials [14]. The remaining ashes are generally landfilled (frequently after a solidification process with Portland cement) or used in different applications according to the policy of each country. Indeed, the rate of usage varies between 100 wt.% and 0 wt.% (i.e., 100 wt.% disposed of in landfills) and the related regulation diverge among countries, particularly in the EU [11; 13; 14; 15; 49; 76]. Before reuse, different treatments may be applied to reduce the potential mobility of potentially hazardous constituents from IBA. Depending on the intended IBA application, these treatments may include natural weathering, washing, heat treatment, particle density-based separation, and stabilization with the addition of hydraulic binders [11; 77]. Natural weathering is the most commonly used treatment. In this case, IBA is stored outdoors and exposed to ambient conditions for 6 to 20 weeks to undergo an aging/weathering process [14; 55].