Sorption and biodegradation of six pharmaceutically active compounds under four different redox conditions

Abstract

This study explored the removal of six pharmaceutically active compounds (PhACs) in lab-scale experiments with sediments under four redox conditions, namely aerobic, nitrate reducing, sulfate reducing, and methanogenic conditions using batch and column set-ups. Redox conditions were found to influence PhAC removal by sorption and biodegradation. The most optimal PhAC removal was observed at the outer ranges of the redox spectrum, i.e. either aerobic or deep anaerobic (sulfate reducing and methanogenic conditions), whereas nitrate reducing conditions were found least effective for PhACs biodegradation and sorption. For instance, sorption coefficient K values for metoprolol in column experiments were 90, 65, 42 and 11 L/kg for sulfate reducing, methanogenic, aerobic and nitrate reducing conditions, respectively. For the same conditions K values for propranolol were 101, 94, 55 and 55 L/kg, respectively. As expected, biodegradation efficiencies were highest under aerobic conditions, showing >99% removal of caffeine and naproxen, but no removal for propranolol and carbamazepine. The adaptive capacity of sediment was demonstrated by pre-exposure to PhACs leading to improved PhAC biodegradation. The results of this study indicate the necessity to combine diverse redox conditions, including aerobic conditions, for maximizing PhAC removal by sorption and biodegradation. Furthermore, our findings stress the need for additional treatment measures as recalcitrant PhACs are not effectively removed under any redox condition.

Trace Organic Removal during River Bank Filtration for Two Types of Sediment

“…With regard to metoprolol, for which degradation rate constants of 19.7 day −1 (core A) and 4.9 day −1 (core B) have been observed, our results concur with results reported by other authors, who found a strong redox dependency of metoprolol degradation by means of laboratory experiments [18,67], and also confirm our previous findings [66].…”

Using recirculating flumes and a response surface model to investigate the role of hyporheic exchange and bacterial diversity on micropollutant half-lives

“…The main removal process of ACS and CBZ in this experiment was expected to be biodegradation. Although CBZ was oen found persistent and thus not biodegradable in sediment-water systems, 8,13,23,55 in experiments comprising longer incubation times, slow biodegradation has been observed previously. 9,[56][57][58] Biodegradation of ACS in WWTPs was only recently reported and has evolved either by independent evolution or global spreading of organisms or genes responsible for the biotransformation pathway.…”

Anaerobic manganese- or iron-mediated pharmaceutical degradation in water

“…Pharmaceutical removal efficiency during biological Fe(III) production is similar, or even less than that with only NO3 -. In previous studies, the biodegradation of six selected pharmaceuticals is inefficient with NO3 - [268,339] , similar to the results in this study. In addition, the results indicate that in our experiments Fe(II) is a more reactive electron donor for denitrification than the pharmaceutical compounds tested.…”

“…Under anaerobic conditions, microorganisms can use different alternative electron acceptors, including nitrate, Mn, Fe, sulphate, and CO2 [74] . The biodegradation of various pharmaceuticals has been observed under these different redox conditions [74,339] . However, in comparison with other redox conditions, biodegradation of pharmaceuticals under Mn and Fe reducing conditions has been insufficiently addressed.…”

“…The samples for pharmaceutical measurement were centrifuged at 10,000 rpm for 10 min immediately after taken. The supernatant was collected and pre-treated by solid phase extraction (SPE) as described previously [339] . The recovery rate of SPE is 85 -115%.…”