Potentials of duckweed (Lemna gibba) for treatment of 1,4-dioxane containing wastewater using duckweed multi-ponds system

Abstract Duckweed (Lemna gibba) was investigated for the treatment of wastewater containing 1,4-dioxane (e.g., polyester industry wastewater). Three continuous flow duckweed-pond systems (DWP), i.e., one pond, two ponds, and three ponds, were operated achieving different hydraulic retention time (HRT) of 2, 4 and 6 d, respectively. Results indicated that DWP3 is the most efficient one in 1,4-dioxane and NH 4 -N removals from wastewater. 1,4-dioxane and NH 4 -N removal efficiencies by DWP3 (56.9 ± 25% and 87.2 ± 7.1%, respectively) were slightly higher than that obtained by DWP2 (44.8 ± 19.6% and 81.9 ± 8.6%, respectively). It was found that, at DWP3, the pH value was reduced from 8.80 to 7.45, the dissolved oxygen (DO) was increased from 3.5 ± 1.9 to 7.5 ± 3 mg/L, and the concentration of total dissolved solids (TDS) was decreased from 921.5 ± 120.6 to 837.6 ± 83.6 mg/L. Eventually, duckweed (Lemna gibba) is effective to remove 1,4-dioxane from wastewater, representing an eco-friendly, effective and low operation and maintenance costs technology.