Research

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.

Publication List

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. 

Recent Publications:

1. Korak, J.A.*; Mungan, A.L.; Watts, L.T. Critical Review of Waste Brine Management Strategies for Drinking Water Treatment Using Strong Base Ion Exchange. Journal of Hazardous Materials 2023, 441, 129473. https://doi.org/10.1016/j.jhazmat.2022.129473
2. Flint, L.C; Arias-Paić M.S.; Korak, J.A.*. Removal of hexavalent chromium by anion exchange: non-target anion behavior and practical implications. Environ. Sci.: Water Res. Technol 2021, 7, 2397–2413. https://doi.org/10.1039/d1ew00382h
3. Korak, J.A.*, Flint, L. C. & Arias-Paić, M. Decreasing waste brine volume from anion exchange with nanofiltration: implications for multiple treatment cycles. Environmental Science: Water Research and Technology, 2021, 7, 886-903. https://doi.org/10.1039/d1ew00001b
4. Arias-Paic, M.S.*; and Korak, J.A.; Forward osmosis for ion exchange waste brine management. Environmental Science and Technology Letters, 2020, 7 (2), 111-117.  https://doi.org/10.1021/acs.estlett.9b00733

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 monitoring 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.

Recent Publications:

1. Korak, J.A. and McKay, G.M. Use of Fluorescence and Absorbance as Surrogates for the Aromaticity and Molecular Weight of Dissolved Organic Matter. Environmental Science: Processes and Impacts.  Advance Article
   https://doi.org/10.1039/D4EM00183D
2. Korak, J.A. and McKay, G.M. Meta-Analysis of Optical Properties for the Characterization of Dissolved Organic Matter. Environmental Science & Technology, 2024, 58 (17) 7380-7392. https://doi.org/10.1021/acs.est.3c10627
3. Ulliman, S.L.; Korak, J.A.; Linden, K.G.; Rosario-Ortiz, F.L. Methodology for Selection of Optical Parameters as Wastewater Effluent Organic Matter Surrogates. Water Research, 2020, 170, 115321.  https://doi.org10.1016/j.watres.2019.115321

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 utilities 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.

Recent Publications: 

Warren, M.; Crespo-Medina, M.; Ramirez-Toro, Rodriguez, R.; Hernandez, M.; Rosario-Ortiz, F.L.; Korak, J.A. Water quality in Puerto Rico after Hurricane Maria: Challenges associated with lead assessment and potential regulatory implications. ACS ES&T Water, 2023, 3 (2), 354-365. https://doi.org/ 10.1021/acsestwater.2c00425