High proportions of petroleum loss ascribed to volatilization rather than to microbial degradation in greenhouse-enhanced biopile

• Published in: Journal of cleaner production 2021-06, Vol.303, p.127084, Article 127084
• Main Authors: Zheng, Yi-Ming, Xi, Bei-Dou, Shan, Guang-Chun, Yu, Min-Da, Cui, Jun, Wei, Kun-Hao, Liu, Hong-Bao, He, Xiao-Song
• Format: Article
• Language: English
• Subjects: Greenhouse-enhanced biopile; Microbial community; Numerical simulation; Petroleum-contaminated soil; Temperature
• ISSN: 0959-6526; 1879-1786
• DOI: 10.1016/j.jclepro.2021.127084

Biopile could improve the remediation efficiency of petroleum-contaminated soil, but the volatilization of petroleum also occurred during the biopile process. To quantitatively estimate the roles of volatilization and microbial degradation during the biopile process, a field-scale greenhouse-enhanced biopile was applied. Four group field trials added cow dung and exogenous microorganism were conducted in greenhouses built in Qingyang, China. Cow dung had little effect on the microbial community of biopile. Incubated-microbes initially changed the microbial community composition, but had few effects on petroleum degradation due to the continuous mesophilic-range (298–323 K) and excessive soil drying. In greenhouses, temperature could affect not only microbial degradation but also volatilization of petroleum. COMSOL Multiphysics was adopted to estimate the volatilization of petroleum during greenhouse-enhanced biopile (GEB) process. The heat transfer between the biopile and the air in GEB process can be divided into three stages: forward heat transfer, two-way heat transfer and reverse heat transfer. The heat transfer drove the volatilization of petroleum in GEB process, and the optimum radius of biopile was 0.15 m. The half-life of petroleum in a surface of 5 cm biopile was 3 days. In GEB process, the removal of volatile organic compounds in surface soils reached 80% within 30 days, while that of semi-volatile compounds and non-volatile compounds were only 50% and 30%, respectively. Only volatile organic compounds were removed from the inner soil without turning over. The removal efficiency of petroleum doubled in GEB than that in normal temperature (298 K), and it correlated significantly with the ambient temperature during the GEB process. [Display omitted] •Petroleum was barely degraded during greenhouse-enhanced biopile (GEB) process.•The volatilization of petroleum was estimated by numerical simulation.•The removal efficiency of petroleum doubled in GEB than that in outdoor (298 K).