PARENT SESSION
PM5 - Fate & Effects of Metals in Wetland & Terrestrial Systems
Monday, 18 November 2002
8:00 AM to 6:30 PM
Exhibit Hall

(P260) Comparison of a microcosm-scale and full-scale constructed wetland treatment system designed to treat a copper-contaminated wastewater.

Murray-Gulde, Cynthia^*,1, Huddleston, George², Rodgers, John¹, ¹ Clemson University, Pendleton, SC, USA² ENTRIX, Clemson, SC, USA

ABSTRACT- Performance was evaluated for a full-scale constructed wetland treatment system designed for treatment of a copper contaminated wastewater stream. Design of the full-scale system involved theoretical and physical modeling of the constructed wetland system, with a primary objective of poising the system to limit copper bioavailability. Performance objectives for this constructed wetland treatment system were to decrease total copper to <22 g/L and to eliminate toxicity (Ceriodaphnia dubia; 7-d, static/renewal). The microcosm/physical model predicted overall copper removal from simulated wastewater to be 73% (±14) with the inflow acid-soluble copper concentrations averaging 46(±9)g Cu/L while average outflow copper concentrations were 12 g Cu/L (±7) following a 48-h HRT. Simulated wastewater was toxic to C. dubia, while no toxicity was observed in the post-treatment outflow. Monitoring of the full-scale system began in Spring 2001 and continues. Inflow wastewaster concentrations averaged 27 (± 11) g Cu/L and outflow averaged 5 (±2) g Cu/L, with 75% (±8) overall copper removal. Inflow water was toxic to C. dubia, while no toxicity was observed in outflow water. Hydrosoil redox potential in the microcosm and full-scale systems (average = −125 and −133 mV, respectively) and AVS:SECu (3.1:0.04 and 2.0:0.04, respectively) indicated that the system was poised to limit bioavailable copper, with no adverse seasonal effects on wetland performance. A comparison of the microcosm and full-scale results indicated that this microcosm-scale constructed wetland system accurately predicted the performance of the full-scale system. However, information on the functional roles of the wetland macrofeatures (vegetation and hydrosoil) were discernable in the full-scale system and not in the microcosm system. The function and performance information gained from this research allows for ready transfer of this mitigation technology to other sites.

Key words: Constructed wetland, copper, AVS, bioavailability