TY - JOUR
T1 - Enhancing bioremediation of oil-contaminated soils by controlling nutrient dispersion using dual characteristics of soil pore structure
AU - Mori, Yasushi
AU - Suetsugu, Atsushi
AU - Matsumoto, Yuko
AU - Fujihara, Atsushi
AU - Suyama, Kosuke
N1 - Funding Information:
The authors are grateful to bachelors students who supported the flow experiment for this paper in 2005. We are also grateful to Ayayo Ohira for her support with the biological experiment. This work was partially supported by the Japan Society for the Promotion of Science, NEXT program (GS021), 2011–2014, and a Grant-in-Aid for Scientific Research (C) , 18510074 , 2006–2008.
PY - 2013/2
Y1 - 2013/2
N2 - Soil structure is heterogeneous with cracks or macropores allowing bypass flow, which may lead to applied chemicals avoiding interaction with soil particles or the contaminated area. We investigated the bioremediation efficiency of oil-contaminated soils by applying suction at the bottom of soil columns during bioremediation. Unsaturated flow conditions were investigated so as to avoid bypass flow and achieve sufficient dispersion of chemicals in the soil column. The boundary conditions at the bottom of the soil columns were 0. kPa (saturated flow) and -3. kPa (unsaturated flow), and were applied to a volcanic ash soil with and without macropores. Unsaturated flow was achieved with -3. kPa and an injection rate of 1/10 of the saturated hydraulic conductivity. The resultant biological activities of the effluent increased dramatically in the unsaturated flow with macropores condition. Unsaturated conditions prevented bypass flow and allowed dispersion of the injected nutrients. Unsaturated flow achieved 60-80% of saturation, which enhanced biological activity in the soil column. Remediation results were better for unsaturated conditions because of greater biological activity. Also, unsaturated flow with macropores achieved even remediation efficiency from upper through lower positions in the column. Finally, taking the applied solution volume into consideration, unsaturated flow with -3. kPa achieved a 10 times higher efficiency when compared with conventional saturated flow application. These results suggest that effective use of nutrients or remediation chemicals is possible by avoiding bypass flow and enhancing biological activity using relatively simple and inexpensive techniques.
AB - Soil structure is heterogeneous with cracks or macropores allowing bypass flow, which may lead to applied chemicals avoiding interaction with soil particles or the contaminated area. We investigated the bioremediation efficiency of oil-contaminated soils by applying suction at the bottom of soil columns during bioremediation. Unsaturated flow conditions were investigated so as to avoid bypass flow and achieve sufficient dispersion of chemicals in the soil column. The boundary conditions at the bottom of the soil columns were 0. kPa (saturated flow) and -3. kPa (unsaturated flow), and were applied to a volcanic ash soil with and without macropores. Unsaturated flow was achieved with -3. kPa and an injection rate of 1/10 of the saturated hydraulic conductivity. The resultant biological activities of the effluent increased dramatically in the unsaturated flow with macropores condition. Unsaturated conditions prevented bypass flow and allowed dispersion of the injected nutrients. Unsaturated flow achieved 60-80% of saturation, which enhanced biological activity in the soil column. Remediation results were better for unsaturated conditions because of greater biological activity. Also, unsaturated flow with macropores achieved even remediation efficiency from upper through lower positions in the column. Finally, taking the applied solution volume into consideration, unsaturated flow with -3. kPa achieved a 10 times higher efficiency when compared with conventional saturated flow application. These results suggest that effective use of nutrients or remediation chemicals is possible by avoiding bypass flow and enhancing biological activity using relatively simple and inexpensive techniques.
KW - Bioremediation
KW - Bypass flow
KW - Oil contaminated soils
KW - Solute transport
KW - Unsaturated zone
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U2 - 10.1016/j.ecoleng.2012.12.009
DO - 10.1016/j.ecoleng.2012.12.009
M3 - Article
AN - SCOPUS:84872174020
VL - 51
SP - 237
EP - 243
JO - Ecological Engineering
JF - Ecological Engineering
SN - 0925-8574
ER -