Studies on the Dynamic Process to Remove Single and Joint Sulfadiazine Pollution by Vetiveria zizanioides from Aqueous Media

In order to investigate the removal capacity of Vetiveria zizanioides for single treatments of sulfadiazine(SDZ) and joint treatments with different kinds of sulfonamides, an experiment was conducted under the condition of simulated hydroponics in greenhouse for 15 days. Contaminants under study included single kind of SDZ with initial concentration of 100 μg/L, at the same time, 5 kinds of sulfonamides(sulfapyridine, sulfadiazine, sulfamethoxazole, sulfadimethoxine, sulfaquinoline) with each concentration of 100 μg/L were added to the hydroponic solution. The growth index of V. zizanioides, the concentration change of SDZ in hydroponic solution and V. zizanioides tissues were collected, the purposes were to evaluate the absorption, enrichment, transfer and remove of SDZ by V. zizanioides. The results indicated that there were no significant differences in the length of the shoots and roots of V. zizanioides under SDZ or SAs stress compared with the no pollutants group. On the 15^th day of contamination exposure, the removal rates of single(C_{P + SDZ}) and joint(A_{P + SAs}) treatments in the hydroponic solution of V. zizanioides group were 38.49% and 33.47% respectively, which were 13.47% and 15.45% higher than those of the control group without plants. The removal ability of V. zizanioides for SDZ in the single pollution group was significantly stronger than that of SAs joint pollution. The residual concentrations in 2 groups of hydroponic solutions were 61.51 μg/L and 66.52 μg/L respectively. And the degradation period of 99% SDZ were 88 and 111 days, which were 49, 75 days shorter than those in the control group without plants. The enrichment coefficients of roots and shoots in the C_{P + SDZ} group were higher than those in the A_{P + SAs} groups. The accumulation ability of roots of V. zizanioides to SDZ was stronger than that of shoots, and the enrichment coefficients were all less than 1. The transfer coefficient TF was within the range of 0.2–0.4. Although the concentration of SDZ absorbed and transported by V. zizanioides directly were limited, but it could effectively promote the removal of SDZ in water. The net removal rate of V. zizanioides in SDZ hydroponic solution was directly related to the removal rate of hydroponic solution , cultivate time, shoots enrichment coefficient and SDZ concentration of shoots.