Long-Term Assessment of 1,4-Dioxane Uptake via Duckweed with Emphasis on Operational Parameters

Abstract

Duckweed (Lemna Gibba) was successfully used for phytoremediation of wastewater containing 1,4-dioxane, which could also result in biomass with high protein and carbon content. 1,4-dioxane is not easily removed or separated from wastewater by traditional physicochemical processes such as coagulation and activated carbon adsorption because of its high solubility [1]. Three duckweed-pond continual streams (DWs) lab-scale reactors, i.e., one pond (DW1), two ponds (DW2), and three ponds (DW3), were operated at variable hydraulic retention times (HRTs) of 2, 4, and 6 days respectively that are designed to treat wastewater containing 1,4dioxane. The results showed that the removal efficiency of 1,4 dioxane, COD, TOC, and ammonia were quite high in the DW3 which had the highest removal efficiency in 1,4-dioxane and NH4-N. 1,4-Dioxane and NH4-N removal efficiencies using DW3 (i.e., 56.9 ± 25% and 87.2 ± 7.1%, respectively) were slightly higher than that obtained using DW2 (i.e., 44.8 ± 19.6% and 81.9 ± 8.6%, respectively). Further, it was noted that, at DW3, the average effluent pH decreased that range from (8.80) to (7.45, c (TDS) decreased that range from( 921.5 ± 120.6) to (837.6 ± 83.6) mg/L, and Dissolved Oxygen (DO) increased that range from (3.5 ± 1.9) to (7.5 ± 3) mg/L. Eventually, DW removed 1,4dioxane effectively from wastewater, representing an effective, low operation, eco-friendly, and maintenance costs technology.