## 2 Materials and Methods  
The materials used for the research were plastic waste obtained from recycling of used vehicles (ground and mixed, consisting of both hard and soft plastics, additionally contaminated with inorganic substances) and foils and plastic bags (can be treated as a homogeneous substance) contaminated with organic and inorganic substances. A common feature of the selected samples was the presence of PVC-type plastics containing significant amounts of chlorine. Migration of chlorine was described in the paper [22]. Before further testing, the waste was ground and homogenized. Tests of the low-temperature pyrolysis process were carried out on a test stand consisting of a pyrolytic chamber with a volume of 25 dm\({}^{3}\) and a pyrolytic gas cooler made of a DN 25 pipe with a length of 1000 mm. The main chamber was electrically heated. The pyrolysis chamber is made of cube-shaped alloy steel and its dimensions are: 400/250/250 (mm). It is shell-heated with electric heaters. The maximum operating temperature of the chamber is 500 \({}^{\circ}\)C. The heaters work in a fireproof coating. The chamber is closed with a special cover to prevent air inflow. In the upper right corner of the chamber there is a connection for the discharge of pyrolysis gases. A pipe-in-pipe gas cooler is connected to the stub pipe. The cooling medium is water. The cooler has the ability to regulate the water temperature in the range from 15 to 50 \({}^{\circ}\)C. At the cooler outlet, there is a built-in separator separating the gas fraction from the liquid fraction. The stand is shown schematically in Figure 1.  
The experiment consisted of placing a waste sample of about 750 g in a cold chamber, closing the chamber thoroughly (in order to cut off the air supply) and starting a set of built-in heaters. The process of chamber heating was completed when the temperature inside the chamber reached 425 \({}^{\circ}\)C (such a temperature was selected on the basis of previously conducted tests [7]). This temperature was reached eighty minutes after the heaters were  
Figure 1: Scheme of the test stand for carrying out the pyrolysis process. switched on. At the same time, pyrolytic oil accumulated in the separator was collected from the separator. The total sulfur content was determined using the high-temperature combustion method. The test consisted in burning a sample of the substance in an electric furnace with a ceramic tube at a temperature of 950 \({}^{\circ}\)C and the absorption of SO\({}_{2}\) was generated during combustion in hydrogen peroxide, located in a flask connected to the furnace. Then the resulting solution, after boiling, was titrated with NaOH. The sulfur content in the tested sample was calculated from the formula:  
\[S^{a}=\frac{(V_{1}-V_{2})*0.0008}{m}*100\ [\%] \tag{1}\]  
where:  
* \(S^{a}\)--sulfur content in the tested sample (%);
* \(V_{1}\)--amount of NaOH used to titrate the tested sample (mL);
* \(V_{2}\)--the amount of NaOH used for the titration of the blank (mL);
* 0.0008--mass of sulfur corresponding to 1 cm\({}^{3}\) of 0.05 n sodium hydroxide solution (g/cm\({}^{3}\));
* \(m\)--mass of the waste sample (g). Determination of total nitrogen content was conducted (this nitrogen combines nitrate, nitrite, organic and ammonium). The determination was carried out in two phases. First, a sample of the waste had to be mineralized with the addition of sulfuric acid (VI) and a catalyst. Then, distillation of the obtained solution after mineralization containing ammonia was carried out, together with the addition of NaOH and indicator. The final stage of the determination was the titration of the distillate receiver, which was hydrochloric acid, with sodium hydroxide.