Hydrocarbon removal in an experimental constructed wetland lysimeter

Omari K.O., . and Revitt D.M., . and Garelick H., . and Shutes R.B.E., . (2003) Hydrocarbon removal in an experimental constructed wetland lysimeter. [Proceedings Paper]

Two subsurface flow lysimeters control and experimental were constructed in an open area under the direct influence of atmospheric processes and filled with a substrate of pea gravel 3-6 mm to a depth of 60 cm. Each of the lysimeters was connected through three pipes located at different heights in the end walls to a head-tank at the outlet and a flow meter at the inlet. Water can be continously circulated within each lysimeter. The flow rate can be varied to provide different residence times. A tube attached to the inlet pipe enables the pollutant dosing solution to be fed into the lysimeters at a controlled rate. The experimental lysimeter or small-scale constructed wetland was planted with Typha seedlings at a density of 7.5 plants/m2. A diesel oil was selected for the dosing experiments because initial GC/MS analysis showed the presence of distinct alkane peaks in the range C-9 to C-26. Both reedbeds experimental and control were treated with the same aqueous concentrations of diesel oil under identical dosing conditions. The average removal efficiencies at the three monitored levels top middle and bottom in the sub-surface systems were 95.8 92.2 and 86.7 in the experimental lysimeter and 93.2 84.9 and 68.7 in the control lysimeter. These high levels are almost certainly due in part to the high adsorption capacity of the new gravel substrate. However overall differences in the removal efficiencies of the planted and the unplanted lysimeters as well as at different depths in both systems indicate that other removal processes are also occuring. The populations of bacteria actinomycetes and fungi were determined in the experimental and control lysimeters both before and after dosing with diesel oil/industrial methylated spirit/water solution. A comparison of the microbial populations in the experimental and control lysimeters top and bottom sections before and after dosing with diesel oil/industrial methylated spirit/water solution shows that that were an increase in microbial populations after dosing. Generally microbial populations in the experimental lysimeter were higher than in the control lysimeter p 0.001. The presence of Typha will cause an increase of oxygen in the root rhizosphere zone in the top section of the experimental lysimeter. Both lysimeters were supplied with oxygen via pumps located in the head tanks but this appeared to have no effect on the distribution of microorganisms in their substrates. There was no difference between the microbial population members in the two lysimeters before planting of the experimental system with Typha. The hydrocarbon removal results and mechanism including microbial degradation plant uptake and adsorption onto gravel substrate and plant surfaces will be modelled to provide information to assist the design of full scale constructed wetland systems.

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Abstract

Two subsurface flow lysimeters control and experimental were constructed in an open area under the direct influence of atmospheric processes and filled with a substrate of pea gravel 3-6 mm to a depth of 60 cm. Each of the lysimeters was connected through three pipes located at different heights in the end walls to a head-tank at the outlet and a flow meter at the inlet. Water can be continously circulated within each lysimeter. The flow rate can be varied to provide different residence times. A tube attached to the inlet pipe enables the pollutant dosing solution to be fed into the lysimeters at a controlled rate. The experimental lysimeter or small-scale constructed wetland was planted with Typha seedlings at a density of 7.5 plants/m2. A diesel oil was selected for the dosing experiments because initial GC/MS analysis showed the presence of distinct alkane peaks in the range C-9 to C-26. Both reedbeds experimental and control were treated with the same aqueous concentrations of diesel oil under identical dosing conditions. The average removal efficiencies at the three monitored levels top middle and bottom in the sub-surface systems were 95.8 92.2 and 86.7 in the experimental lysimeter and 93.2 84.9 and 68.7 in the control lysimeter. These high levels are almost certainly due in part to the high adsorption capacity of the new gravel substrate. However overall differences in the removal efficiencies of the planted and the unplanted lysimeters as well as at different depths in both systems indicate that other removal processes are also occuring. The populations of bacteria actinomycetes and fungi were determined in the experimental and control lysimeters both before and after dosing with diesel oil/industrial methylated spirit/water solution. A comparison of the microbial populations in the experimental and control lysimeters top and bottom sections before and after dosing with diesel oil/industrial methylated spirit/water solution shows that that were an increase in microbial populations after dosing. Generally microbial populations in the experimental lysimeter were higher than in the control lysimeter p 0.001. The presence of Typha will cause an increase of oxygen in the root rhizosphere zone in the top section of the experimental lysimeter. Both lysimeters were supplied with oxygen via pumps located in the head tanks but this appeared to have no effect on the distribution of microorganisms in their substrates. There was no difference between the microbial population members in the two lysimeters before planting of the experimental system with Typha. The hydrocarbon removal results and mechanism including microbial degradation plant uptake and adsorption onto gravel substrate and plant surfaces will be modelled to provide information to assist the design of full scale constructed wetland systems.

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Item Type:	Proceedings Paper
Additional Information:	Summary En
AGROVOC Term:	LYSIMETERS
AGROVOC Term:	HYDROCARBONS
AGROVOC Term:	DIESEL OIL
AGROVOC Term:	MICROBIAL ECOLOGY
AGROVOC Term:	POPULATION DENSITY
AGROVOC Term:	BIOLOGICAL ANALYSIS
AGROVOC Term:	UNITED KINGDOM
Geographical Term:	MALAYSIA
Depositing User:	Ms. Norfaezah Khomsan
Last Modified:	24 Apr 2025 05:27
URI:	http://webagris.upm.edu.my/id/eprint/16115

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