Nutrient and Trace Element Uptake By Cattail During Remediation of Municipal Biosolids Using a Wetland System: A Microcosm Experiment.

Nutrient and trace element uptake by cattail during remediation of municipal biosolids using a wetland system: a microcosm experiment Adenike Hassan1, Francis Zvomuya1 and Lisette Ross2 1Department of Soil Science, University of Manitoba, Winnipeg MB. R3T 2N2 Canada 2Ducks unlimited A-1238 Chevrier Blvd Winnipeg MB. R3T 1Y3 Canada hassana3@cc.umanitoba.ca Oral presentation Land spreading is currently the most commonly used method of disposal of municipal biosolids in many jurisdictions, including Manitoba. However, the technique is expensive and presents a risk of pathogen and contaminant transfer during transportation and spreading of the biosolids. This growth room study examined the effectiveness of a constructed wetland as an alternative in-situ remediation approach. The wetland microcosm experiment was laid out in a completely randomized design with a 2 x 2 factorial treatment structure and three replications. The two factors tested were growth medium (PB and PBS) and harvest frequency [one harvest vs. two harvests per growing season (cycle)]. Two controls, which consisted of the growth media with no plants, were included for comparison. Cattail seedlings were transplanted into pots containing 4.54 kg (dry wt.) of either biosolids from the lagoon's primary cell (PB) or a 1:1 mixture of PB and soil (PBS), above which a 10-cm deep water column was maintained. Readings were taken weekly to determine the oxidation-reduction potential in the sediment and water column as well as the pH, EC and dissolved oxygen (DO) concentration in the water column. Plants were harvested and analyzed for nutrients and trace elements. Preliminary results indicate that redox potential in the biosolids was significantly lower in the control than in the PB and PBS. Zinc, copper, nitrogen and phosphorus uptake were significantly higher in the PB than in the PBS. Repeated harvesting increased nutrient and trace element uptake compared to a single harvest. Keywords: Wetlands, Remediation