This study examined the ability of duckweed (Lemna minor) to remove soluble lead from water. The duckweed was obtained from the Devils Lake wastewater treatment plant in North Dakota. The viable aquatic plants were exposed to a single dose of lead (from Pb(NO3)2) at a concentration of 5.0 mg/l for a time period of 21 days. Lead concentrations were measured in the water daily and in the biomass at the conclusion of the experiment. All measurements were done in triplicate and performed in accordance with standard methods. These data were used to calculate the removal efficiency with respect to time, and to provide the necessary empirical constants to model the removal behavior. Viable biomass removed 85-90% of the lead, viable duckweed previously exposed to lead removed 70-80% of the lead, non-viable biomass (control group) removed 60-75% of the lead, and there was no removal in the 'no-biomass' control group. Based on these results we conclude that the viable biomass is effective in removing lead present at sub-lethal levels.
Bibliographical noteFunding Information:
The authors thank Dr Charles Moretti, Dr Rashid Hasan, Dr John Erjavec and Joe Miller for their valuable advice and Dr Harvey Gullicks for use of the Environmental Engineering Laboratory. We also wish to express gratitude to ND-EPSCoR (North Dakota Experimental Program to Stimulate Competitive Research) for financial assistance to this study.
- Kinetic model
- Lemna minor