The Korak Research Group has three main research areas. Check out the "Projects" tab to learn about recent and ongoing work in each area. We are always looking for collaborators with similar interests.
Efficient Waste Management for Water Treatment Processes
Efficient water treatment requires more than removing unwanted constituents or contaminants from water. In many cases, the technology exists to purify any water, but the process is inefficient or uneconomical due to low water recovery or expensive waste management. We research holistic strategies to provide clean water while simultaneously managing the waste. Residuals management is not an afterthought but an integral part of developing robust water treatment processes.
One example is the management of spent brine from ion exchange processes. Resin is regenerated periodically using a highly concentrated salt solution. While the volume of this waste brine is often less than 1% of the total volume of treated water, handling and disposal of the waste brine is the primary economic barrier to implementing ion exchange. Improving waste management would make ion exchange an economical solution for communities with decentralized water sources.
Hexavalent Chromium Removal from Groundwater
- Korak, J.A.; Huggins, R.; Arias-Paic, M.; Nanofiltration to improve process efficiency of hexavalent chromium treatment using ion exchange. Journal-American Water Works Association, 2018, 110 (6), E13-E26. https://doi.org/10.1002/awwa.1051
- Kennedy, A.M.; Korak, J.A.; Flint, L.; Hoffman, C.; Arias-Paic, M. Pilot-scale studies of chromium removal using stannous chloride. Journal-American Water Works Association, 2018,110 (4), E29-E42. https://doi.org/10.1002/awwa.1048
- Korak, J.A.; Huggins, R; Arias-Paic, M. Regeneration of pilot-scale ion exchange columns for hexavalent chromium removal. Water Research, 2017, 118, 141-151. https://doi.org/10.1016/j.watres.2017.03.018
Distribution System Water Quality and Corrosion Control
Internal corrosion of distribution system pipes
Drinking water quality depends on more than just the source water and water treatment process. The distribution system and household plumbing through which water is transmitted from the treatment facility to the consumer has a large impact of water quality. Water distribution systems in the US are aging infrastructure. Water chemistry, pipe and fixture materials, microbiology and system hydraulics all play important roles in maintaining drinking water quality. It is the interaction between factors that determines whether internal corrosion has the potential to release metals (e.g., iron, manganese, lead, and copper) into drinking water or whether chlorine residuals and microbiology safety can be maintained throughout the system.
We focus on system level assessments of lead release and evaluating the potential for adverse water quality when water sources change. With increasing water scarcity, water utlities look to diversify water portfolios using multiple water sources and implementing water reuse. Changing or blending potable water sources changes the water chemistry in distribution systems, which may adversely impact water quality. Proactive planning and developing tools to identify and mitigate impacts is important for maintaining drinking water quality in the future.
Real-time Optical Monitoring and Process Control
Reliable water treatment systems need a robust monitoring strategy that can quickly identify changes in influent water quality and deviations in treatment performance. Dissolved organic matter (DOM) is ubiquitous in all natural waters, and its chemistry can be informative for montioring water treatment performance. The optical properties (e.g., fluorescence and absorbance) of DOM can provide real-time insight into treatment operations or changes in source water quality (e.g., the presence of algal blooms). We focus on identifying the most informative and practical optical metrics to implement via online sensors. An important consideration is that laboratory instruments often have capabilities and features that are not yet available in online sensors. An overarching goal for our research is to develop smart monitoring strategies that leverage the most promising laboratory instrument features and implement them into practical online sensors.
2019-2020: Graduate student Juliette Kaplan is collaborating with a local water utility and design team to conduct bench testing and support pilot testing for a new drinking water treatment plant.
Dissolved Organic Matter Coagulation
- Korak, J.A.; Rosario-Ortiz, F.L.; Summers, R.S. Evaluation of optical surrogates for the characterization of DOM removal by coagulation. Environmental Science: Water Research & Technology, 2015, 1 493-506. https://doi.org/10.1039/C5EW00024F
- Korak, J.A.; Rosario-Ortiz, F.L.; Summers, R.S. Fluorescence characterization of humic substance coagulation: Application of new tools to an old process. In Advances in the Physicochemical Characterization of Organic Matter; Rosario-Ortiz, F.L., Ed; ACS Symposium Series 1160; American Chemical Society: Washington DC, 2014; pp 281-300. https://doi.org/10.1021/bk-2014-1160.ch014
Cyanobacteria Intracellular Organic Matter Release
- Korak, J. A.; Wert, E. C.; Rosario-Ortiz, F. L. Fluorescence spectroscopy as a surrogate for the release of intracellular organic matter upon oxidation of cyanobacteria cells. Journal-American Water Works Association, 2015, 107 (1), E523-E542. https://doi.org/10.5942/jawwa.2015.107.0142
- Korak, J.A.; Wert, E.C.; Rosario-Ortiz, F.L. Evaluating fluorescence spectroscopy as a tool to characterize cyanobacteria intracellular organic matter upon simulated release and oxidation in natural water. Water Research, 2015, 68 432-443. https://doi.org/10.1016/j.watres.2014.09.046
- Wert, E.C., Korak, J.A., Trenholm, R.A., Rosario-Ortiz, F.L. Effect of oxidant exposure on the release of intracellular microcystin, MIB, geosmin from three cyanobacteria. Water Research, 2014, 52, 251-259. https://doi.org/10.1016/j.watres.2013.11.001
Photophysical Properties of Dissolved Organic Matter
- McKay, G.; Korak, J. A.; Rosario-Ortiz, F. L. Temperature dependence of the fluorescence of dissolved organic matter: Implications for DOM photophysics. Environmental Science and Technology, 2018, 52, 9022-9032. https://doi.org/10.1021/acs.est.8b00643
- McKay, G.M.; Korak, J.A.; Erickson, P.R.; Latch, D.E.; McNeill, K.; Rosario-Ortiz, F.L. The case against charge transfer interactions in dissolved organic matter photophysics. Environmental Science and Technology, 2018, 52, 406-414. https://doi.org/10.1021/acs.est.7b03589
- Rosario-Ortiz, F.L.; Korak, J.A.; Oversimplification of Dissolved Organic Matter Fluorescence Analysis: Potential Pitfalls of Current Methods. Environmental Science and Technology, 2017, 51 (2), 759-761. https://doi.org/10.1021/acs.est.6b06133 (Viewpoint Article, not peer-reviewed)
- Cawley, K.M.; Korak, J.A.; Rosario-Ortiz, F.L. Quantum yields for the formation of reactive intermediates from dissolved organic matter samples from the Suwannee River. Environmental Engineering Science, 2015. 32 31-37. https://doi.org/10.1089/ees.2014.0280
- Korak, J.A.; Dotson, A.D.; Summers, R.S.; Rosario-Ortiz, F.L. Critical analysis of commonly used fluorescence metrics to characterize dissolved organic matter. Water Research, 2014, 49, 327–338. https://doi.org/10.1016/j.watres.2013.11.025
- Mostafa, S.; Korak, J.A.; Shimabuku, K; Glover, C.M.; Rosario-Ortiz, F.L. Relation between optical properties and formation of reactive intermediates from different size fractions of organic matter. In Advances in the Physicochemical Characterization of Organic Matter; Rosario-Ortiz, F.L., Ed; ACS Symposium Series 1160; American Chemical Society: Washington DC, 2014; pp 159-179. https://doi.org/10.1021/bk-2014-1160.ch008