## 3 Results and Discussion
### The Total BaPTE Concentration Alue  
Figure 10 presents the results of total _BaPTE_ concentration of the smoke particles from POSS bio-char combustion. In the initial combustion period, the _BaPTE_ value was found to be 23,145.64 to 64,060.91 ng/m\({}^{3}\); then, it continually decreased until the 60 th minute. The _BaPTE_ value was found to be 435.62 to 1746.49 ng/m\({}^{3}\). This result showed that the increase in time period and the POSS bio-char moisture content had a prime influence on decreasing the total PAHs and _BaPTE_ values, synonymous with the TPMC and MMAD values.  
Figure 8: Mass fraction of each PAH component in smoke particle samples from the palm oil sewage sludge bio-char combustion for different clean air speeds and combustion periods (Phe = Phenanthrene, Act = Acenaphthylene, Fle = Fluorene, Nap = Naphthalene, Ace = Acenaphtheene, Ant = Anthracene, IDP = Indeno[1,2,3-cd]pyrene, Flu = Fluoranthene, BaA = Benz[a]anthracene, Chr = Chrysene, Pyr = Pyrene, Bbf = Benzo[b]fluoranthene, BaP = Benzo[a]pyrene, DBA = Dibenz[a,h]anthracene, and BghiPe = Benzo[g,h,i]perylene).  
Figure 9: Mass fraction of each PAH component in smoke particle samples from the palm oil sewage sludge bio-char combustion for different moisture contents and combustion periods (Phe = Phenanthrene, Act = Acenaphthylene, Fle = Fluorene, Nap = Naphthalene, Ace = Acenaphtheene, Ant = Anthracene, IDP = Indeno[1,2,3-cd]pyrene, Flu = Fluoranthene, BaA = Benz[a]anthracene, Chr = Chrysene, Pyr = Pyrene, Bbf = Benzo[b]fluoranthene, Bbf = Benzo[k]fluoranthene, BaP = Benzo[a]pyrene, DBA = Dibenz[a,h]anthracene, and BghiPe = Benzo[g,h,i]perylene).  
The relationship between the \(Tp\) value changed during the POSS bio-char combustion and with the bio-char moisture content. When substituting the a\({}_{0}\), a\({}_{1}\) and a\({}_{2}\) coefficient values which were calculated by using the least-squares method in Equation (8), the equation of the \(Tp\) value changed and could be written as shown in Equation (12). The experimental and predictable total _BaPTE_ values of the POSS bio-char samples throughout the combustion period are presented in Table 2. The results showed that the total _BaPTE_ value of the POSS bio-char burning was between 65.7 and 261.6. The increase in moisture content of the POSS bio-char samples had a high influence on increasing the total _BaPTE_ values. Meanwhile, when increasing the clean air speed, the total _BaPTE_ values decreased.  
\[T_{p}=69.5083-1.1872 MR+0.0056t \tag{12}\]  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Velocity** **(m/s)**} & \multirow{2}{*}{_MR_ **(\%d.b.)**} & \multirow{2}{*}{**Combustion** **Time (min)**} & \(\sum\)_BaPTE Value_ & \multicolumn{2}{c}{\(\sum\)_BaPTE Value Prediction_} \\  & & & **Experiment** & \multicolumn{2}{c}{**(\(\mu\)g/m3)**} & **Zero** & **First** \\ \hline
0.1 & 15 & 60 & 93.1 \(\pm\) 0.6  & 96.4 & 95.6 \\  & 30 & 60 & 141.3 \(\pm\) 0.8  & 152.8 & 155.7 \\  & 45 & 60 & 194.9 \(\pm\) 1.2  & 192.3 & 194.1 \\  & 60 & 60 & 261.6 \(\pm\) 1.5  & 255.1 & 264.6 \\
0.2 & 15 & 55 & 76.2 \(\pm\) 0.3  & 75.2 & 77.9 \\  & 30 & 55 & 118.1 \(\pm\) 0.6  & 123.5 & 121.7 \\  & 45 & 55 & 163.1 \(\pm\) 0.8  & 161.2 & 167.9 \\  & 60 & 55 & 214.9 \(\pm\) 1.2  & 211.3 & 215.1 \\
0.3 & 15 & 50 & 65.7 \(\pm\) 0.3  & 63.6 & 67.5 \\  & 30 & 50 & 104.5 \(\pm\) 0.9  & 101.2 & 105.7 \\  & 45 & 50 & 148.1 \(\pm\) 0.7  & 152.8 & 156.3 \\  & 60 & 50 & 195.4 \(\pm\) 1.0  & 197.1 & 199.1 \\ \hline \hline \end{tabular} a-h Different letters in the same column indicate a significant difference at \(p\)-value (\(p<0.05\)).  
\end{table}
Table 2: The experimental and predictable total _BaPTE_ values of the palm oil sewage sludge bio-char samples throughout the combustion time.  
Figure 10: _BaPTE_ value in the smoke particle samples from the POSS bio-char combustion for different the clean air speeds and moisture contents.