Sequential Managed Aquifer Recharge Technology (SMART) for enhanced removal of trace organic chemicals

Transcription

1 Sequential Managed Aquifer Recharge Technology (SMART) for enhanced removal of trace organic chemicals Karin Hellauer 1, Uwe Hübner 1, Julia Regnery 2, and Jörg E. Drewes 1,2 1 Technical University of Munich (Germany) 2 NSF ERC ReNUWIt, Colorado School of Mines (CO, USA) 1 9 th International Symposium on Managed Aquifer Recharge Mexico City, June th, 2016

2 Engineering natural treatment systems Design and operation of MAR systems as a unit process Understanding boundary conditions Contaminant transport models MAR field site Removal rates for trace organic chemicals (TOrC) R C t v C x D 2 C x 2 C 2

3 1.0 C/C 0 Gemfibrozil C/C 0 Diclofenac Redox-dependent biodegradation oxic suboxic anoxic Regnery et al. J Contam. Hydrol. 2015, 179, Travel time in days

4 Relative abundance Microbiome metabolic function Relative abundance of functional genes related to xenobiotic degradation pathways for soil columns receiving lower and higher amounts of biodegradable dissolved organic carbon (BDOC) Shift in gene abundance toward lower BDOC content Higher BDOC Lower BDOC Li et al., Appl Microbiol Biotechnol 2014, 98,

5 Concept of SMART Sequential Managed Aquifer Recharge Technology Multi-sequence configuration featuring: carbon-rich and predominantly anoxic subsurface conditions, followed by carbon-depleted and predominantly oxic conditions Conceptual design of a full-scale treatment train: Regnery et al. Chemosphere 2016, 154,

6 10 cm 30 cm 50 cm 10 cm 5 cm 5 cm 16,7 cm SMART at lab-scale Hydraulic retention time (HRT) of 4.2 days during the first infiltration step and 3.6 days during the second soil passage with intermediate aeration WWTP Effluent Garching B01 B02 air b1 b2 b3 b4 Oxygen sensor spot Sampling port Effluent 6

7 Δ dissolved organic carbon [mg/l] Δ dissolved oxygen [mg/l] DOC and oxygen consumption aeration aeration 7

8 TOrC removal in the SMART system Enhanced removal of moderate degradable TOrC, e.g., metoprolol, diclofenac No effect on recalcitrant TOrC such as carbamazepine Removal of easy degradable TOrC (e.g., citalopram) during the first infiltration TOrC degrada on [%] HRT [d] Metoprolol Diclofenac Citalopram Aera on 8

9 SMART at full-scale Prairie Waters Project, Aurora Water, Colorado, U.S. Regnery et al. Chemosphere 2016, 154,

10 Effect of multi-sequence configuration Large reduction in DOC (51 ± 8%) and UV 254nm absorbance (51 ± 9%) during RBF passage, reduction of nitrate (63 ± 18%) and dissolution of manganese Redox shift from oxic in the stream to suboxic (absence of dissolved oxygen) and predominantly anoxic (denitrifying) conditions during RBF passage Re-aeration during ARR surface spreading Dissolved manganese and iron in recovered ARR groundwater below U.S. EPA secondary maximum contaminant limit (MCL) of 0.05 mg/l and 0.3 mg/l 10

11 TOrC removal RBF/ARR treatment Regnery et al. Chemosphere 2016, 154,

12 RBF vs. ARR performance Comparison of RBF and ARR wells with <10 days subsurface travel time and <20% dilution with native groundwater Low BDOC/oxic ARR passage outperforms high BDOC/anoxic RBF passage Regnery et al. Chemosphere 2016, 154,

13 ARR performance Comparison of ARR wells with <2 weeks or >2 weeks subsurface travel time and <20% dilution with native groundwater Almost no difference in removal efficiency for moderately degradable TOrC Regnery et al. Chemosphere 2016, 154,

14 Impact of SMART on TOrC removal Significantly improved TOrC removal (i.e., higher biodegradation rate coefficients for moderately biodegradable compounds) compared to just extending travel times in an anoxic aquifer Most of the TOrC attenuation occurs within the first few meters of infiltration under carbon-depleted and predominant oxic conditions Opportunities to further reduce the physical footprint of the recharge facility while still maintaining similar water qualities Regnery et al. Chemosphere 2016, 154,

15 Transfer SMART to other sites First infiltration step Reduction of electron donors, denitrification Short travel times in biologically active system Additional carbon supply needed for denitrifcation of elevated nitrate concentrations Intermediate aeration or ozonation Engineered recharge facility characterized by high hydraulic conductivity and relatively low soil organic carbon content More frequent cleaning cycles or engineered iron filtration step prior to infiltration at elevated iron concentrations (>0.5 mg/l) in the reduced water Second infiltration step Establishing oxic redox conditions 15

16 Acknowledgements Research funded by National Science Foundation - ERC ReNUWIt WateReuse Research Foundation (WRRF-10-05) Role of retention time in the environmental buffer of indirect potable reuse projects Thank you for your attention 16

17 Influence of sorptive processes 17