Operating Bicarbonate-Form versus Chloride-Form Ion Exchange Resins without Regeneration for Natural Organic Matter Removal. Liu, ZH., I. Papineau, M. Mohseni, S. Peldszus, P.R. Bérubé , S. Sauvé, and B. Barbeau , 2021. ACS ES&T Water, 1, 6, 1456–1463
In this collaboration, a team of researchers from British Columbia and Montreal, and chair team member Dr. Sigrid Peldszus looked at ion exchange (IX) as a promising drinking water treatment process for natural organic matter (NOM) removal. More specifically, they investigated at a process called biological ion exchange (BIEX), where IX is operated with infrequent regeneration to favor biomass development on the resins, which benefits NOM removal and reduces brine volumes. For this study, they evaluated the performance of pilot-scale BIEX filtration for NOM removal using parallel bicarbonate-form and chloride-form BIEX filters, which were fed with surface water for 9 months without regeneration. The bicarbonate-form BIEX pilot filters had a slightly lower DOC removal, a higher removal of biodegradable dissolved organic carbon (BDOC) and the removal of disinfection by-product precursors was similar to the chloride-form IX resins. In summary, both resins provide good NOM removal while reducing brine production when operated as BIEX.
Identifying the Best Coagulant for Simultaneous Water Treatment Objectives: Interactions of Mononuclear and Polynuclear Aluminum Species with Different NOM Fractions. Lapointe, M., I. Papineau, S. Peldszus, N. Peleato, and B. Barbeau, 2021. Journal of Water Process Engineering, 40, pp. 1-12.
Researchers from Polytechnique de Montreal, the University of British Columbia and from the Chair, Dr. Sigrid Peldszus, worked on prehydrolyzed coagulants containing polymeric and/or cationic aluminum (Al) species as a treatment for NOM in different source waters. Liquid chromatography-organic carbon detection-organic nitrogen detection (LC-OCD-OND) was used to characterize, and compare residual organic matter after coagulation. Other, more conventional performance parameters such as removal of turbidity, dissolved organic carbon (DOC) and disinfection by product (DBP) precursors in addition to residual aluminum/iron and alkalinity consumption were also assessed. Six different Al coagulant species were evaluated during bench-scale, sand ballasted coagulation tests on three surface waters and removal mechanisms were proposed for NOM fractions. Advantages and disadvantages of using monomeric vs. polymeric species were revealed. Considering all indicators and NOM fractions PAX 14, a slightly prehydrolyzed coagulant (basicity of 23 %), performed best during enhanced coagulation at pH 6.0 and may be considered as an alternative to alum. Overall, prehydrolyzed coagulants were less pH-sensitive for the removal of all NOM fractions, and in general they have a lower alkalinity consumption compared to alum. In conclusion, often only one of these advantages is sufficient to justify the higher cost associated with the use of prehydrolyzed coagulants for municipalities.
Impact of Vacuum UV on Natural and Algal Organic Matter from Cyanobacterial Impacted Waters. Visentin, F., S. Bhartia, M. Mohseni, S. Peldszus, S. Dorner and B. Barbeau, 2020. Environmental Science: Water Research & Technology, 2020, 6, pp. 829-838.
In another collaboration, a similar team of researchers as in the BIEX paper investigated the effects of vacuum UV (VUV) treating waters with and without cyanobacterial blooms. VUV is an advanced oxidation process (AOP), where UV light at wavelengths < 200nm is applied and no chemical addition is required as is typical for other AOPs. VUV was tested on three lake waters with different natural and algal organic matter (NOM/AOM) contents. The main objective was to assess how NOM and AOM were impacted by VUV treatment, and how DBP precursors may be affected. NOM/AOM were characterized by LC-OCD, which utilizes size exclusion chromatography (SEC) to ‘bin’ NOM/AOM fractions, and fluorescence emission-excitation matrix (FEEM), before and after VUV treatment. Results demonstrated that high molecular weight NOM fractions increased, while low molecular weight fractions decreased after VUV treatment. FEEM analysis related certain regions of the humic substances (HS) signal to cyanobacteria blooms. With respect to DBPs, trihalomethane (THM) yield increased by 15-20% after VUV treatment and the HS are the most important fraction causing the increase in DBP formation. Smaller water utilities may want to consider VUV for a range of treatment goals, because it is simpler to operate than other AOPs where chemical addition is required.
