# Waste-to-Energy Process to Recover Dangerous Pollutants in an Environmental Protected Area
## 2 Materials and Methods
### Fuel Production: Waste to Fuel  
The process starts with a waste extraction on trucks. Each sample is characterized, and high calorific value (HCV) and low calorific value (LCV) are measured. This also determines if it necessary to add reagents (soda) to regulate pH and eliminate suspended solids. The mixture must comply with the specifications indicated by the cement industries (Table 2), for which is necessary to add alkaline mixture. Alkalis are added in order to eliminate cyanide contamination in the aqueous effluent. The final fuel mixture is a mixture in which the viscosity has been reduced. In addition, it also meets specifications for mercury content, viscosity, humidity, and heat of combustion. Table 3 shows the number of samples analyzed, the tons of waste extracted from the lagoon, and the waste's calorific value throughout the entire extraction process (Table 3). The year 2016 presented the largest volume of waste extraction, decreasing from that year onward because of the increase in the viscosity parameter. \begin{table}
\begin{tabular}{c c c c c} \hline  & **Units** & **A Layer** & **B Layer** & **C Layer** \\ \hline Volume & m\({}^{3}\) & 998.00 & 694.00 & 45,143.00 \\ \hline Density & Kg/m\({}^{3}\) & 1028.00 & 1045.00 & 1078.05 \\ \hline Weight & T & 1026.00 & 725.00 & 48,666.00 \\ \hline Viscosity & cP & - & - & 38,195.78 \\ \hline Water & \% & 1.00 & 89.30 & 28.28 \\ \cline{2-5}  & T & 10.30 & 647.00 & 13,853.00 \\ \hline Net Calorific Value & Kcal/Kg & 9632 & - & 5610.00 \\ \hline Acidicity & mg KOH/g & 160.00 & 29.70 & 33.20 \\ \cline{2-5}  & t KOH & 164.00 & 22.00 & 1626.00 \\ \hline Sulphur & \% & 1.75 & 0.30 & 5.78 \\ \cline{2-5}  & T & 18.00 & 2.20 & 2831.30 \\ \hline Lead & mg/Kg & 21.70 & 8.60 & 3873.00 \\ \cline{2-5}  & T & 0.022 & 0.006 & 189.70 \\ \hline Zinc & mg/Kg & 71.00 & 97.00 & 997.00 \\ \cline{2-5}  & T & 0.073 & 0.07 & 48.80 \\ \hline Polychlorinated biphenyl, PCBs & mg/Kg & 41.00 & - & 13.36 \\ \cline{2-5}  & Kg & 42.00 & - & 627.00 \\ \hline \end{tabular}
\end{table} 
Table 1: Characteristics of the waste from lagoon under this study. \begin{table}
\begin{tabular}{c c} \hline
**Contaminants** & **Established Limits (mg/m\({}^{3}\))** \\ \hline Solid particles & 30.00 \\ \hline HCl & 10.00 \\ \hline HF & 1.00 \\ \hline NO\({}_{\rm x}\) & 800.00 \\ \hline Dioxins and furans (ng/m\({}^{3}\)) & 0.10 \\ \hline Cd + Tl & 0.05 \\ \cline{2-3} Heavy metals & Hg & 0.05 \\ \cline{2-3} Sb + As + Pb + Cr + Co + Cu \\  +Mn + Ni + V & 0.50 \\ \hline \end{tabular}
\end{table} 
Table 2: Emission limits values. The waste from the lagoon is not treated, but processed with the mixed waste batches by carrying out this process, as follows:  
* Phase separation: the treated waste is a mixture of water with hydrocarbons with a composition of 95% water, 3% solids, and 2% hydrocarbons. This mixture is an emulsion of water/oil or an emulsion of coolant. Through the addition of sulphuric acid, the emulsion is broken, and once the breakage is done, a decantation is carried out. Then 3% of the solids are taken to landfills outside the plant, 95% of the aqueous phase is transferred, if necessary, to a purification phase; if not necessary, it goes directly to the evapo-condensation process and biological treatment, and this is the last treatment process. From there, 2% of the light phase, if possible, proceeds to energy assessment. * Physical-chemical treatment: in the treatment, less waste is contributed to the alternative fuel line. This waste is the emulsion of oil/water in the modelling of metals; the light phase goes to the alternative fuel line to the biological treatment. * Evapo-condensation: this process requires significant amounts of energy, but combined vacuum systems are used to allow low-temperature distillations. It is a triple-effect process composed of three effects or deposits that have a liquid ring heat pump at the end of the third effect.