Research Project Full Title: Coupled ED and NF Treatment System for NOM Removal: Hollow Fiber Membrane Experimental System
Principal Investigator(s): Lynn Katz and Frank Seibert (UT-SRP)
Researchers: Soyoon Kum
Sponsor(s): USEPA WINSSS
Full Abstract: Water disinfection significantly reduces the risk of an outbreak of waterborne pathogens; however, reactions between disinfectants and natural organic matter (NOM) can lead to the formation of disinfection by-products (DBPs) which are potentially carcinogenic. EPA has set federally enforceable maximum contaminant levels (MCLs) that limit DBP concentrations in drinking water. For THMs, the first stage called for an MCL on total trihalomethanes (TTHM) of 0.08 mg/L, while MCLGs were placed on bromodichloromethane (BDCM), dibromochloromethane (CDBM) and bromoform (TBM) of 0.0, 0.06 and 0.0 mg/L respectively. In the second stage the previously set limits and goals were left unchanged, while TCM received a MCLG of 0.07 mg/L. To meet these contaminant levels two main approaches can be taken: reduction of the concentrations of NOM and disinfectants that serve as precursors to the formation of DBPs, or reduction of the concentration of DBPs after they have formed. It has been shown that an overwhelming majority of treatments systems lacking compliance are characterized as small water systems serving less than 10,000. Often these small systems lack the financial or technological means to achieve compliance in the same method of treatment as large water systems, and thus several technologies including hollow fiber membrane air stripping have been researched as solutions to broaden EPA compliance for small water systems. The effectiveness of removing of disinfection by-products using membrane air stripping in comparison to packed tower aeration was first shown in early work by Zander et al., (JAWWA, 1989) in experiments focused on the removal of chloroform, bromoform, and bromodichloromethane among other volatile organic chemicals (VOCs). Comparison showed that hollow fiber membrane (HFM) air stripping produced higher volumetric overall mass transfer coefficients and lower air-to-water ratios than in packed tower aeration. However, advances in membrane technology by Liqui-Cell suggest that application of this process for THM removals in small systems may be particularly attractive. The goals of this project are to assess the potential of this process for THM removal in small water systems.
Additional Links: https://www.umass.edu/winsss/