|Ph.D Student||Gur-Reznik Shirra|
|Subject||Fate of Pharmaceutical Active Compounds (PhACs) during|
Advanced Wastewater Treatment Processes
|Department||Department of Civil and Environmental Engineering||Supervisor||Professor Emeritus Carlos Dosoretz|
|Full Thesis text|
The presence of micropollutants in treated wastewater effluents is of increasing concern due to conservation of freshwater resources and for safeguarding the aquatic environment. The overall aim of the present research was to examine the input-output relationship of pharmaceutical model compounds during advanced wastewater treatment processes under controlled conditions.
The interaction of selected pharmaceutical model compounds with effluent organic matter, their relative distribution between sludge and effluents, as well as their fate during desalination and post-desalination treatment of tertiary effluents were studied. The rejection efficiencies applying nonporous membranes of decreasing selectivity, three reverse osmosis-RO (sea, brackish and tap water types) and two nanofiltration-NF (loose and tight), in combination with non-thermal plasma (NTP) oxidation was examined. Carbamazepine, an antiepileptic drug, and two representatives iodinated contrast media (ICM), diatrizoate, ionic, and iopromide, non-ionic, were used as pharmaceutical tracers.
Rejections of the model pharmaceuticals from effluents were comparatively tested with ultrapure water in order to establish the influence of background matrix. Effect of seasonal changes, ionic strength, effluent dilution, membrane pressure and spiking concentration on the rejection were also examined. The results strongly indicate that RO is required for a reliable and constant high quality of the effluents, independent of membrane resolution, water matrix or season. In the NF membranes, season and water matrix were found to markedly influence the rejection. These season-dependent interactions were strengthened during summer, increasing the removal of NF membranes, but weakened during winter, reducing the rejection. Dialysis experiments suggested that these interactions occur with the effluent organic matter fraction < 1000 Da.
Oxidation of the model pharmaceuticals in the feed and brines of effluent desalination by NTP resulted very effectively, reducing their concentration, including ICM which are usually considered as resistant to oxidation. NTP mediated oxidation was high even in the presence of relatively high background dissolved organic matter levels, as normally found in treated effluents and desalination brines, and without the need for chemical additives as required in other advanced oxidation processes. Based on transformation and de-iodination profiles and extents, two distinct patterns of initial oxidation were established and differentiated for the two ICM tested in this research. As a result of the NTP oxidation, treated brines and effluents displayed a substantial increase in biodegradability. Our results evidenced that ICM can serve as excellent markers for process evaluation and environmental regulation due to their relative resistance to oxidation processes and biological transformation as well as the endogenic iodine tracing.