Woodchip bioreactors are increasingly being applied to remove nitrate from aqueous environments. However, in addition to nitrate, trace organics such as pharmaceuticals and anticorrosive agents are also a concern. The aim of this study is to investigate the removal efficiency and to elucidate the degradation mechanisms in woodchip bioreactors for six widely used and often detected pharmaceuticals and two anticorrosive substances.  The eight target compounds in this study were acetaminophen, ibuprofen, caffeine, sulfathiazole, benzotriazole, 5-methyl-1-H-benzotriazole, carbamazepine and lincomycin. The experiments were conducted in a up-flow mode column reactor (10 cm i.d. × 50 cm) with 700 g woodchips. Liquid chromatography−tandem mass spectrometry equipped with an electrospray ionization interface were used for analysing the eight target compounds.  The results showed consistantly high removal efficiency of nitrate (~80%); the degree of removal the eight compounds through woodchip reactor is very compound dependent. Complete removal was observed for acetaminophen while ibuprofen was persistant. Soprtion and biodegradation were found to be the two major degradation mechanisms, and compound physical-chemical properties significantly affected their removal efficiencies. Compounds such as acetaminophen and caffiene were removed mainly through biodegradation processes while sorption process dominated rest of analytes’ removal. The source of the woodchip (US and Taiwan), the age of the woodchip, the initial concentration of target compounds (100 and 1000 μg/L) and the operating flow rate (1 and 5 mL/min) were also investigated to assess changing conditions on the overall removal efficiency. In addition, the same woodchip reactor experiments were done in different regions of the world (Taipei vs. California) and different season of the year to evalute potential locational effects. Consistent and promising results were observed in both places.

Harnessing woodchips to remove pharmaceuticals and anticorrosive substances

256th National Meeting (2018)

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