Pyrolytic Treatment and Fertility Enhancement of Soils Contaminated with Heavy Hydrocarbons

• Published in: Environmental science & technology Vol. 50; no. 5; pp. 2498 - 2506
• Main Authors: Vidonish, Julia E, Zygourakis, Kyriacos, Masiello, Caroline A, Gao, Xiaodong, Mathieu, Jacques, Alvarez, Pedro J. J
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 01.03.2016
• Subjects: Arabidopsis - growth & development; Arabidopsis thaliana; Biomass; Carbon; Fertilizers; Hydrocarbons; Hydrocarbons - analysis; Hydrocarbons - chemistry; Incineration; Lactuca - growth & development; Lactuca sativa; Petroleum production; Plant growth; Polycyclic aromatic hydrocarbons; Polycyclic Aromatic Hydrocarbons - analysis; Polycyclic Aromatic Hydrocarbons - chemistry; Soil - chemistry; Soil contamination; Soil fertility; Soil Pollutants - analysis; Soil Pollutants - chemistry; Technology - methods; Thermogravimetry
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/acs.est.5b02620

Pyrolysis of contaminated soils at 420 °C converted recalcitrant heavy hydrocarbons into “char” (a carbonaceous material similar to petroleum coke) and enhanced soil fertility. Pyrolytic treatment reduced total petroleum hydrocarbons (TPH) to below regulatory standards (typically <1% by weight) within 3 h using only 40–60% of the energy required for incineration at 600–1200 °C. Formation of polycyclic aromatic hydrocarbons (PAHs) was not observed, with post-pyrolysis levels well below applicable standards. Plant growth studies showed a higher biomass production of Arabidopsis thaliana and Lactuca sativa (Simpson black-seeded lettuce) (80–900% heavier) in pyrolyzed soils than in contaminated or incinerated soils. Elemental analysis showed that pyrolyzed soils contained more carbon than incinerated soils (1.4–3.2% versus 0.3–0.4%). The stark color differences between pyrolyzed and incinerated soils suggest that the carbonaceous material produced via pyrolysis was dispersed in the form of a layer coating the soil particles. Overall, these results suggest that soil pyrolysis could be a viable thermal treatment to quickly remediate soils impacted by weathered oil while improving soil fertility, potentially enhancing revegetation.