Antibiotics and sweeteners in the aquatic environment: biodegradability, formation of phototransformation products, and in vitro toxicity

Abstract

In the present study, in vitro toxicity as well as biopersistence and photopersistence of four artificial sweeteners (acesulfame, cyclamate, saccharine, and sucralose) and five antibiotics (levofloxacin, lincomycin, linezolid, m a r b o f l o x a c i n , a n d s a r a f l o x a c i n ) a n d o f t h e i r phototransformation products (PTPs) were investigated. Furthermore, antibiotic activity was evaluated after UV irradiation and after exposure to inocula of a sewage treatment plant. The study reveals that most of the tested compounds and their PTPs were neither readily nor inherently biodegradable in the Organisation for Economic Co-operation and Development (OECD)-biodegradability tests. The study further demonstrates that PTPs are formed upon irradiation with an Hg lamp (UV light) and, to a lesser extent, upon irradiation with a Xe lamp (mimics sunlight). Comparing the nonirradiated with the corresponding irradiated solutions, a higher chronic toxicity against bacteria was found for the irradiated solutions of linezolid. Neither cytotoxicity nor genotoxicity was found in human cervical (HeLa) and liver (Hep-G2) cells for any of the investigated compounds or their PTPs. Antimicrobial activity of the tested fluoroquinolones was reduced after UV treatment, but it was not reduced after a 28-day exposure to inocula of a sewage treatment plant. This comparative study shows that PTPs can be formed as a result of UV treatment. The study further demonstrated that UV irradiation can be effective in reducing the antimicrobial activity of antibiotics, and * Marlies Bergheim

Use of column experiments to investigate the fate of organic micropollutants – a review

“…They were thus able to confirm the transport behavior observed in the laboratory experiments through their own field measurements. Bertelkamp et al (2012) also compared the degradation of organic micropollutants in column experiments with field measurement. Results from laboratory experiments and from investigations at a riverbank filtration site both showed that the charge and LogD of the micropollutants defined their biodegradation potential.…”

“…Other materials used for columns include PVC (e.g., Bertelkamp et al, Figure 2. Schema of common setups used in column experiments: (a) unsaturated/leaching experiments (e.g., Siemens et al, 2010); a fluctuating water table is established in some experimental setups (e.g., Sinke et al, 1998), (b) saturated/groundwater flow experiments (e.g., Scheytt et al, 2004), and (c) saturated columns connected in series in order to measure the evolution of hydrochemical parameters (such as the oxidation-reduction potential) along the flow path (e.g., Nay et al, 1999). 2012; Greenhagen et al, 2014;Salvia et al, 2014;Sinke et al, 1998), polyethylene (Bertelkamp et al, 2012), and aluminum (Burke et al, 2014).…”

“…Short columns enable fast experiments and many repetitions, while longer columns need more time for equilibration before the actual start of the experiment but allow longer reaction times (which means that more reactions can be distinguished) and more complex settings (e.g., the establishment of redox zonings). The dimensions of columns vary considerably due to the broad range of research applications; for example, lengths have been reported ranging from 5 cm (Estrella et al, 1993;Teijón et al, 2014) to 2.4 m (Cordy et al, 2004), and inner diameters have been reported ranging from 2 cm (Teijón et al, 2014) to 36 cm (Bertelkamp et al, 2012(Bertelkamp et al, , 2014. The choice of a reasonable length-to-diameter ratio is important if scaling effects are to be avoided.…”

“…The tubing and other materials reported are commonly made from Teflon/PTFE (e.g., De Wilde et al, 2009;Fan et al, 2011;Ke et al, 2012;Strauss et al, 2011;Teijón et al, 2014) or stainless steel (e.g., Ke et al, 2012;Nay et al, 1999;Teijón et al, 2014), which are known to be inert materials. Other materials that have been used in column experiments are Pharmed tubing (Strauss et al, 2011), (dark) polyethylene (Bertelkamp et al, 2012(Bertelkamp et al, , 2014, PVC, (black) Tygon tubing, vinyl, polysulfone, brass (Greenhagen et al, 2014), polypropylene, and silicone (Srivastava et al, 2009). However, the influence of many of these reported materials on organic compounds is unknown and may be problematic, as is the case for Pharmed tubing, silicone, and Tygon tubing (Hebig et al, 2014).…”

“…There are similar uncertainties in reported flow velocities to those previously mentioned for porosities, as authors do not always state clearly whether they are referring to porewater velocity or Darcy velocity. Various types of fluid have been used as solvents in column experiments depending on their objectives, including natural (site-specific) groundwater (Greenhagen et al, 2014;Mersmann et al, 2002;Preuss et al, 2001;Scheytt et al, 2004) or surface water (e.g., Banzhaf et al, 2012;Baumgarten et al, 2011;Burke et al, 2014;Schaffer et al, 2012), model or artificial (ground)water (De Wilde et al, 2009;Estrella et al, 1993;Murillo-Torres et al, 2012;Xu et al, 2010), treated wastewater (e.g., Alotaibi et al, 2015;Cordy et al, 2004;Ke et al, 2012), tap water (Bertelkamp et al, 2012;Burke et al, 2013), distilled water (Aga et al, 2003), ultrapure water (Simon et al, 2000), and even liquid manure (Strauss et al, 2011).…”