Microbiome-Triggered Transformations of Trace Organic Chemicals in the Presence of Effluent Organic Matter in Managed Aquifer Recharge (MAR) Systems

Abstract

Microbiome triggered transformations of trace organic chemicals in the 2 presence of effluent organic matter in managed aquifer recharge (MAR)

Analyzing (Initial) Biotransformation Reactions as an Organizing Principle for Unraveling the Extent of Trace Organic Chemical Biotransformation in Biofiltration Systems

“…Experimental Setup. Experiments were conducted in a sand column system, which was previously described by Hellauer et al 25 In short, the system consists of two large columns (A1 and A2, height of 0.5 m, inner diameter of 0.14 m) filled with technical sand (0.2−1.0 mm) and four short columns (b1−b4, 0.3 m, 0.09 m, aquifer material: d 50 = 0.8 mm, foc = 0.003%) connected in series (Figure 1). The effluent of column A2 was reaerated with compressed air to provide oxic conditions in the second column system.…”

“…WWTP in Garching, Germany (during sampling for batch experiments), have been described previously. 25 Importantly, the system showed rapid depletion of dissolved oxygen leading to anoxic conditions in deeper layers of the first infiltration stage (columns A1 and A2). Reaeration resulted in oxic to partly suboxic (defined as DO < 1 mg/L and NO 3 -N removal < 0.5 mg/L 30 ) conditions in subsequent columns b1−b4.…”

“…DOC decreased from 6.8 ± 1.1 to 4.7 ± 0.2 mg/L before reaeration and was further reduced to 3.1 ± 1.1 mg/L in the effluent of column b4. A more comprehensive characterization of bulk organic matter changes, including three-dimensional fluorescence and FT-ICR-MS measurements, can be found in ref 25. Measured influent concentrations of ammonia remained below 0.1 mg/L NH 4 + -N throughout the experiment, and the pH was stable within the system (mean of 8.3 ± 0.3).…”

“…Thus, in this study we focused on biotransformation of a very broad selection of TOrCs with a wide range of functional characteristics in a well-characterized column system. 25 The column system was designed with a first infiltration step characterized by fast degradation of biodegradable DOC leading to rapid depletion of dissolved oxygen and anoxic conditions followed by reaeration and a subsequent set of four columns operated under mostly oxic and carbon-limited conditions. Our previous studies showed that some TOrCs are well transformed in the first column while biotransformation of others benefits from oxic and carbon-limited conditions after reaeration.…”

“…Our previous studies showed that some TOrCs are well transformed in the first column while biotransformation of others benefits from oxic and carbon-limited conditions after reaeration. 6,25,26 We also complemented the continuously operated column studies with batch experiments using material from different columns of the biofiltration system. The purpose of those batch studies was twofold.…”