Long term laboratory column experiments to simulate bank filtration: Factors controlling removal of sulfamethoxazole

Biodegradation of sulfamethoxazole: current knowledge and perspectives

“…In addition to these sludge and manure fermentation studies, anaerobic and anoxic column tests (as described in the previous section) were carried out with surface water containing 0.25 and 4.5 μg/L SMX in order to model microbial degradation during bank filtration. The results showed no SMX degradation at the lower concentration (0.25 μg/L) but 27 % removal (anoxic; 49-day half-life) and 51 % removal (anaerobic; 16-day half-life) after 14 days at the higher SMX concentration (4.5 μg/L); these SMX removal rates are significantly less than those measured under aerobic conditions in the same study (see previous section) (Baumgarten et al 2011). A batch test carried out in soil samples under anaerobic conditions with water containing SMX combined with four other pharmaceutical compounds (40 μg SMX/kg soil; described in previous section) resulted in a measured SMX half-life ranging from 15.3 to 18.3 days, which agrees with the results of Baumgarten et al (2011).…”

“…The results showed no SMX degradation at the lower concentration (0.25 μg/L) but 27 % removal (anoxic; 49-day half-life) and 51 % removal (anaerobic; 16-day half-life) after 14 days at the higher SMX concentration (4.5 μg/L); these SMX removal rates are significantly less than those measured under aerobic conditions in the same study (see previous section) (Baumgarten et al 2011). A batch test carried out in soil samples under anaerobic conditions with water containing SMX combined with four other pharmaceutical compounds (40 μg SMX/kg soil; described in previous section) resulted in a measured SMX half-life ranging from 15.3 to 18.3 days, which agrees with the results of Baumgarten et al (2011). This is greater than the aerobic half-life but considerably less than the 59-day half-life observed in sterilized soil and indicates successful biodegradation under anaerobic conditions (Lin and Gan 2011).…”

“…The column test (2 m filter bed height, 0.155 m diameter) used technical quartz sand loaded with surface water containing 0.25 or 4.5 μg/L SMX (0.13 m/days, 14 days HRT) and resulted in 60 % SMX removal after 14 days exposure to 0.25 μg/L SMX and 90 % removal after 3.5 days exposure to 4.5 μg/L SMX. The estimated SMX half-life under these conditions ranged from 1 to 9 days (Baumgarten et al 2011). This experiment was also carried out under anoxic and anaerobic conditions, which will be discussed in the following section.…”

Role of the hyporheic heterotrophic biofilm on transformation and toxicity of pesticides

“…Water flow and recirculation through these different porous media should permit contact with micro-organisms that perform different degradation steps with various redox potential of a single toxicant. Concerning redox conditions, Baumgarten et al (2011) outline that bank filtration under aerobic conditions should be suitable to remove SMX to levels below 0.12 mg.L x1 . However, previous field studies suggested that organic pollutants were removed more effectively under anoxic (97%) and anaerobic conditions than under aerobic (64%) conditions (Schmidt et al, 2004;Jekel and Gruenheid, 2005).…”

“…In laboratory microcosms investigations, Jekel and Gruenheid (2005), Gruenheid et al (2005) and Baumgarten et al (2011) demonstrated that in bank filtration, as in long retention soil column the major factors that influence the degradation of bulk and trace organics are redox conditions and retention times. In laboratory columns degradation of the antibiotic sulfamethoxazole takes months (Baumgarten et al, 2011) and led to the conclusion that it is essential to provide several weeks or even months of travel time in bank filtration to allow the degradation of this toxicant. The most efficient conditions to give evidence of this retention capacity must consider the physical, chemical and biological conditions of the natural that is to say microbial community of interstitial biofilm and reproduce it in artificial hyporheic sediment.…”