PLUG-FLOW REACTOR-BASED ANTIBIOTIC AND NUTRIENT REMOVAL BY VETIVER GRASS (CHRYSOPOGON ZIZANIOIDES)

Prolonged persistence of chemotherapeutic drugs in treated wastewater is the primary reason for the emergence of antimicrobial resistance. Innovative, economical, and environment-friendly remediation techniques are necessary to address this emerging health issue. Due to their high solubility, antibiotics are poorly retained in animal physiological systems, and a majority of them are excreted as active compounds that enter the environment via municipal and hospital sewage. Although antibiotics like ciprofloxacin (CIP) and tetracycline (TTC) are susceptible to photodegradation in clear water, they cannot be degraded in wastewater due to certain physico-chemcial conditions, such as an abundance of organic matter. Vetiver System (VS) has been proven to be a well-accepted phytoremediation technique all over the world due to its excellent capability to uptake a wide range of contaminants from both soil and water. In this study, we investigated the potential of Vetiver (Chrysopogon zizanioides), a fast-growing perennial grass with high biomass that can be grown hydroponically, to remove two widely used pharmaceutical compounds (CIP and TTC) from secondary wastewater effluent in a plug-flow-reactor-based, floating, macrophyte-constructed wetland. Our previous studies have shown the capability of vetiver grass to remove both antibiotics (CIP and TTC) and nutrients from a wastewater matrix in a bench-scale study. This continuous flow system reached a steady-state after seven days, and vetiver grass significantly (p<0.05) removed 93% and 97% of the CIP and TTC (initial concentration 10 mg/L) respectively during the steady-state period. Vetiver grass also significantly (p<0.05) removed 93% and 84% total nitrogen and phosphorus respectively from the secondary wastewater effluent. At steady-state, 84% of chemical oxygen demand was removed by the vetiver grass. During the experiment period, a 4% increase in the vetiver biomass was also observed.