# Insights into PCDD/Fs and PAHs in Biomass Boilers Envisaging Risks of Ash Use as Fertilizers
## 3 Experimental Part
### Results and Discussion
#### 3.2.1 Chemical Composition and PCDD/F in Biomass, Sludge and Soil
Additionally, PCDD/Fs may originate by photolytic formation from other precursors like chlorophenols, polychlorinated phenoxyphenols and polychlorinated diphenylthers with origin in pesticides production or their progressive degradation, as well as other chemicals such as the widely used biocide triclosan [238]. Forest fires, which are suspected to produce PCDD/Fs [160], also appear to have mainly a dispersive effect of OCDD and precursors existing in vegetation and soils [239]. Predominance of OCDD in the environment may also be enhanced by aging due to preferential degradation of the lower chlorinated PCDD/Fs by natural UV photolysis [240; 241; 242]. The calculated \(\Sigma\)PCDD/Fs and TEQs using UB, MD and LB approaches for ND, are presented in Table 5. The differences between LB and UB reveal how discrepant the reported \(\Sigma\)PCDD/Fs and TEQs can be, for each sample, depending on the ND attribution option. The quantification levels (EQLs), i.e., the sensitivity of the analytical methodology, have a great influence on \(\Sigma\)PCDD/Fs and TEQs. The sludge is an extreme case of this influence; \(\Sigma\)PCDD/Fs may be assumed as 0, or 105, or 210 ng/kg, and TEQ as 0, or 13.5, or 26.9 ng WHO\({}_{2005}\)-TEQ/kg, depending on the ND option. Independently of samples having detectable congeners or ND for all, TEQ values using the MB option are similar for the various samples, 14 ng WHO\({}_{2005}\)-TEQ/kg, 15 ng WHO\({}_{1998}\)-TEQ/kg and 12 ng I-TEQ/kg. Using the UB option, TEQs are also identical among samples. For the LB option, TEQs of biomass blends vary from 0.009-0.43 ng WHO\({}_{2005}\)-TEQ/kg. Similar TEQs were obtained by [PERSON] et al. [74] in pine needles and cones, 0.66 and 0.33 ng I-TEQ/kg, with preponderance of OCDD, followed by 1,2,3,4,6,7,8-HpCDD and 1,2,3,4,6,7,8-HpCDF, and some other congeners, generally in low quantities. The TEQs calculated with different protocols are very similar; WHO\({}_{2005}\)-TEQs are about 10% higher than I-TEQs, and about 10% lower than the WHO\({}_{1998}\)-TEQs, in accordance with [PERSON] et al. [66]. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**(ng/kg)** & **Sludge Mix** & \multirow{2}{*}{**Soil**} & **Biomass Blend** & **Biomass Blend** & **Biomass Blend** \\
**(1/2/2 = 70/30)** & & **BFB3** & **BFB4** & **GF** \\ \hline
2,3,7,8-TCDF & ND(2.0) 1 & ND(2.0) & ND(2.0) & ND(2.0) & ND(2.0) \\
1,2,3,7,8-PcCDF & ND(12) & ND(12) & ND(12) & ND(12) & ND(12) \\
2,3,4,7,8-PcCDF & ND(12) & ND(12) & ND(12) & ND(12) & ND(12) \\
1,2,3,4,7,8-HxCDF & ND(12) & ND(12) & ND(12) & ND(12) & ND(12) \\
1,2,3,6,7,8-HxCDF & ND(12) & ND(12) & ND(12) & ND(12) & ND(12) \\
2,3,4,6,7,8-HxCDF & ND(12) & ND(12) & ND(12) & ND(12) & ND(12) \\
1,2,3,7,8,9-HxCDF & ND(12) & ND(12) & ND(12) & ND(12) & ND(12) \\
1,2,3,4,6,7,8-HpCDF & ND(12) & ND(12) & ND(12) & ND(12) & ND(12) \\
1,2,3,4,7,8,9-HpCDF & ND(12) & ND(12) & ND(12) & ND(12) & ND(12) \\ OCDF & ND(24) & ND(24) & ND(24) & ND(24) & ND(24) \\
2,3,7,8-TCDD & ND(2.0) & ND(2.0) & ND(2.0) & ND(2.0) & ND(2.0) \\
1,2,3,7,8-PeCDD & ND(12) & ND(12) & ND(12) & ND(12) & ND(12) \\
1,2,3,4,7,8-HxCDD & ND(12) & ND(12) & ND(12) & ND(12) & ND(12) \\
1,2,3,6,7,8-HxCDD & ND(12) & ND(12) & ND(12) & ND(12) & ND(12) \\
1,2,3,7,8,9-HxCDD & ND(12) & ND(12) & ND(12) & ND(12) & ND(12) \\
1,2,3,4,6,7,8-HpCDD & ND(12) & ND(12) & ND(12) & ND(12) & ND(12) \\ OCDD & ND(25) & 43 & 260 & 67 & 29 \\ \hline \(\Sigma\) PCDD/F MB 2 & 105 & 135 & 382 & 160 & 122 \\ LB/UB 2 & 0/210 & 43/228 & 295/468 & 67/252 & 29/214 \\ \hline I-TEQ MB & 11.8 & 11.8 & 12.3 & 11.9 & 11.8 \\ \hline WHO\({}_{1998}\)-TEQ MB & 14.8 & 14.8 & 15.1 & 14.8 & 14.8 \\ \hline WHO\({}_{2005}\)-TEQ MB & 13.5 & 13.5 & 13.8 & 13.5 & 13.5 \\ LB/UB & 0/26.9 & 0.01/26.9 & 0.43/27.2 & 0.02/26.9 & 0.009/26.9 \\ \hline \hline \end{tabular}  
* 1 ND—non-detected, (EQL)—Estimated Quantification Level, 2 LB—Lower-Bound (ND = 0), MB—Medium-Bound (ND = EQL/2), UB—Upper Bound (ND = EQL).  
\end{table} 
Table 5: PCDD/Fs and TEQs of biomass blends, sludge and soil, in dry base.