Membrane Filtration of Challenging Surface Waters- Design of Pre-treatment Based on the Structure of Membrane Fouling Layer

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Many water facilities in Canada are under boil water advisories because their municipal water is not safe to drink; numerous water treatment plants are not able to meet the potentially carcinogenic chlorine disinfection by-products (THMs) regulations. This project is a part of a global strategy to improve water quality and decrease THMs by the use of membrane technology. Nanofiltration (NF) has become widely used in potable water treatment as a method that can meet increasingly stringent water quality regulations and THMs standards. However, a major problem with this approach is NF fouling, which is loosely defined as the loss of performance and increase in plant operation cost due to formation of undesirable deposits (i.e. fouling layer) on the membrane surface. Given that many surface water sources in Canada contain major membrane foulants in high concentrations, understanding the mechanism of fouling and fouling control is of utmost interest to the designers and owners of water treatment systems. The overall objective of the proposed research is to control membrane fouling and significantly reduce operating costs of membrane systems by increasing their operational life. In this proposal, I will address two sub-objectives that will help to advance my overall research program: 1) study fouling mechanisms using new membrane autopsy methods that are applicable to membranes used for filtration of challenging surface waters, and 2) design a customizable pre-treatment process that will lead to the formation of a fouling layer with high permeability to minimize fouling. Two doctoral, three masters and a number of undergraduate students will be trained during this research. These students will have a unique set of skills that is urgently needed in the Canadian water treatment industry, particularly in applications where membranes are being used to produce drinking water. The graduate students will be trained on the application of leading edge technologies such as, Small Angle Neutron Scattering (SANS) and Fourier Transform Infrared (FTIR) Spectroscopy with an Attenuated Total Reflectance (ATR) for water treatment. Control of membrane filter fouling will increase filter life, which will result in millions of dollars in savings each year to individual municipalities and water co-operatives. Currently, owners of Canadian plants operating on waters most challenging to membrane filtration consult with international companies on membrane autopsies and methods to reduce membrane fouling. This research will provide targeted strategies to minimize fouling of membranes operating on Canadian waters.