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The Removal Of Pharmaceuticals From Wastewater By Anaerobic Digestion

Congress: 2015
Author(s): Kaitlin Ramsay, Ole Pahl, Moyra McNaughtan, Colin Hunter
Glasgow Caledonian University1

Keyword(s): Sub-theme 13: Non-conventional sources of water,
Abstract Ramsay, K1 supervised by Pahl, O1., McNaughtan, M1. and Hunter, C1.

1 Glasgow Caledonian University, School of Engineering and Built Environment, Cowcaddens Road, Glasgow, G4 0BA. Contact Email: Kaitlin.Ramsay@gcu.ac.uk

Introduction: Many pharmaceuticals are partially metabolised and both the parent compound and its active metabolites are excreted via the urine or faeces. Unwanted or out-of-date pharmaceutical products are also often disposed of via the toilet. The resultant pharmaceutical residues reach wastewater treatment plants (WWTP), which are not capable of fully removing all of these compounds prior to distributing treated water back into the environment (Halling-Sorensen, 1998; Hedgespeth, 2012; Guerra, 2014; Pills, 2012). Whilst the concentrations of these micropollutants are expected to be relatively low, there is a lack of knowledge in regards to the fate of these substances and their bioaccumulation throughout the environment could impose irreversible effects (Diaz-Cruz et al., 2003).
The anaerobic digestion (AD) process has been widely adopted by industry to facilitate the breakdown of sewage sludge and research suggests that it also increases pharmaceutical removal rates (Samaras et al., 2013). This report will determine the pharmaceutical removal efficiency of AD. Crucially, as the majority of pharmaceutical residues of concern lies with the aqueous phase of wastewater, it will investigate the direct anaerobic treatment of wastewater.

Methodology: Two anaerobic digesters (20L; 2L inoculum:18L substrate; 5 days hydraulic retention time) have been inoculated and fed with artificial wastewater that has been prepared in accordance to the OECD guidelines (OECD, 2001). Digesters will be used for long term process monitoring and for production of inoculums for batch tests. Batch tests are set to mimic the same conditions of the reactors at a working volume of 400ml and will evaluate the impact of temperature and loading on process performance. The project will determine the effects of temperature on pharmaceutical removal by applying psychrophilic (5-25C) and mesophilic (25-40C) conditions to each reactor (Connaughton et al., 2006). The AD process is monitored by measuring: biogas production by gas chromatography, volatile fatty acids formation by liquid chromatography, removal of chemical oxygen demand (COD) and nitrogen transformations (TKN, TAN, nitrate).
Once steady state of the AD process is established, wastewater will be spiked with priority pharmaceuticals at relevant concentrations: Atenolol (8.626g/L), Carbamazepine (0.289g/L), Ciprofloxacin (1.885g/L), Clarithromycin (1.855g/L), Fluoxetine (1.543g/L), Naproxen (25.732g/L), Oxytetracycline (3.388g/L), Paracetamol (46.752g/L), Ranitidine (5.377g/L) and Simvastatin (1.994g/L). The realistic concentrations calculated are based on 2012/13 national (Scottish) community consumption (Source: Personal Communication, Helwig (to be written up)). Their removal will be detected by liquid chromatography/ mass spectrometry (Thermal Fisher Q Exactive).

Results and Discussion: In the absence of pharmaceuticals, batch tests mimicking the reactors have shown activity in both mesophilic and psychrophillic conditions, with COD removal rates of 94.4 (+/- 1.98)% and 49.4 (+/- 4.98)% respectively. An increase of total ammoniacal nitrogen % (TAN) was identified throughout all batch samples. Whilst COD removal is common in both aerobic and anaerobic conditions, an increase of TAN% is only affiliated with the latter. Therefore, the initial batch tests have shown a positive performance of anaerobic activity in psychrophilic and mesophilic temperatures. The efficiency of psychrophilic AD is expected to increase once the bacterial matter adapts to the conditions of a lower temperature.

Conclusion: Initial batch tests established positive AD activity, enabling the application of pharmaceuticals. Batch tests identifying the effects of AD on caffeine, carbamazepine and lidocaine are currently on trial, results are to be expected by November 2014. The addition of caffeine will be used to monitor the AD process as it is typically removed during conventional treatment. Should the initial results to be reported here show potential of AD in this application, then longer term work will include membrane filtration. 1. Connaughton, S., Collins, G. & O'Flaherty, V. 2006, "Psychrophilic and mesophilic anaerobic digestion of brewery effluent: A comparative study", Water research, vol. 40, no. 13, pp. 2503-2510.

2. Dı́az-Cruz, M.S., López de Alda, M.J. & Barceló, D. 2003, "Environmental behavior and analysis of veterinary and human drugs in soils, sediments and sludge", TrAC Trends in Analytical Chemistry, vol. 22, no. 6, pp. 340-351.

3. Guerra, P., Kim, M., Shah, A., Alaee, M. & Smyth, S.A. 2014, "Occurrence and fate of antibiotic, analgesic/anti-inflammatory, and antifungal compounds in five wastewater treatment processes", Science of The Total Environment, vol. 473--474, pp. 235-243.

4. Halling-Sørensen, B., Nors Nielsen, S., Lanzky, P.F., Ingerslev, F., Holten Lützhøft, H.C. & Jørgensen, S.E. 1998, "Occurrence, fate and effects of pharmaceutical substances in the environment- A review", Chemosphere, vol. 36, no. 2, pp. 357-393.

5. Hedgespeth, M.L., Sapozhnikova, Y., Pennington, P., Clum, A., Fairey, A. & Wirth, E. 2012, "Pharmaceuticals and personal care products (PPCPs) in treated wastewater discharges into Charleston Harbor, South Carolina", Science of The Total Environment, vol. 437, pp. 1-9.

6. OECD (2001),Test No. 303: Simulation Test - Aerobic Sewage Treatment -- A: Activated Sludge Units; B: Biofilms, OECD Guidelines for the Testing of Chemicals, Section 3, OECD Publishing. doi: 10.1787/9789264070424-en

7. PILLS project. 2012. Pharmaceutical residues in the aquatic system -- a challenge for the future. Insights and activities of the European cooperation project PILLS. Emschergenossenschaft, Essen, Germany.

8. Samaras, V.G., Stasinakis, A.S., Mamais, D., Thomaidis, N.S. & Lekkas, T.D. 2013, "Fate of selected pharmaceuticals and synthetic endocrine disrupting compounds during wastewater treatment and sludge anaerobic digestion", Journal of hazardous materials, vol. 244--245, pp. 259-267.

2011 IWRA - International Water Resources Association office@iwra.org - http://www.iwra.org - Admin