Effect of activated carbon and biochars on the bioavailability of polycyclic aromatic hydrocarbons in different industrially contaminated soils
2016
Kołtowski, Michał | Hilber, Isabel | Bucheli, Thomas D. | Oleszczuk, Patryk
Coal production negatively affects the environment by the emission of polycyclic aromatic hydrocarbons (PAHs). Two soils (KOK and KB) from a coking plant area was investigated and their total PAH concentration was 40 and 17 mg/kg for the sum (∑) 16 US EPA PAHs, respectively. A third soil was sampled from a bitumen plant area and was characterized by 9 mg/kg ∑16 US EPA PAHs. To reduce the freely dissolved concentration (Cfᵣₑₑ) of the PAHs in the soil pore water, active carbon (AC) and two biochars pyrolysed from wheat straw (biochar-S) and willow (biochar-W) were added to the soils at 0.5–5 % (w/w), each. The AC performed best and reduced the Cfᵣₑₑ by 51–98 % already at the lowest dose. The biochars needed doses up to 2.5 % to significantly reduce the Cfᵣₑₑ by 44–86 % in the biochar-S and by 37–68 % in the biochar-W amended soils. The high black carbon (BC) content of up to 2.3 % in the Silesian soils competed with the sorption sites of the carbon amendments and the performance of the remediation was a consequence of the contaminant’s source and the distribution between the BC and the AC/biochars. In contrast, the carbon amendment could best reduce the Cfᵣₑₑ in the Lublin soil where the BC content was normal (0.05 %). It is therefore crucial to know the contaminant’s source and history of a sample/site to choose the appropriate carbon amendment not only for remediation success but also for economic reasons.
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