Green remediation of veterinary antibiotics in soil-water systems.

摘要

Veterinary antibiotics (VAs) are considered emerging contaminants of concern. Considerable efforts have been made to understand the fate and transport of VAs in soil and water environment and very few have attempted to develop novel remediation strategies to overcome the problem of antibiotic resistance and potential toxicity to aquatic species. To our knowledge, the present study is a pioneer study in which it attempts to develop a low-cost, "green" remediation technique utilizing a waste by-product of the drinking water treatment industry, namely, the Al-based water treatment residuals (Al-WTR), as a sorbent to stabilize tetracycline (TTC) and oxytetracycline (OTC) in aqueous medium, manure piles and manure-treated soil. The ultimate goal of the study was to evaluate the effectiveness of Al-WTR in treating manure, soils, and manure-amended soils to immobilize tetracyclines (TCs) to lower risk associated with TCs in environment. We conducted: i) laboratory batch sorption study followed by modeling and surface spectroscopic characterization to understand the extent and mechanism of TTC/OTC retention by Al-WTR, ii) short-term incubation study to evaluate the effectiveness of Al-WTR in immobilizing and stabilizing TTC and OTC in manure, soils, and manure-amended soils under static conditions, and iii) long -term greenhouse column study to evaluate the effectiveness of Al-WTR in immobilizing and stabilizing TTC and OTC in soils and manure amended soils under dynamic conditions in a controlled environment. Results from the batch sorption study showed that Al-WTR has high sorption capacity for TTC and OTC as a function of solution properties. This, along with the rapid sorption kinetics and low release potential make them excellent sorbents for TCs removal from aqueous medium. Results from modeling and spectroscopic studies suggest that TTC and OTC are adsorbed on Al-WTR surface via strong inner-sphere mechanism, indicating permanent retention. Short term incubation and long term greenhouse column studies showed immobilization of TTC and OTC in Al-WTR amended soils and manure amended soils. LC/MS/MS analysis did not reveal any known detectable degradates or metabolites of TCs other than very low concentration of daughter compounds. Greenhouse column studies also showed that Al-WTR application significantly reduces plant available and water soluble TCs from soils and manure-amended soils. Overall, this research demonstrated the potential of Al-WTR to develop into an effective, low-cost, green remediation technology for TC-contaminated soil-water systems.