AWWA WQTC59026

The Minneapolis Water Works (MWW) has been conducting long-term ultrafiltration membrane studies for its future 70-mgd Columbia Heights Membrane Filtration Plant (CHMFP) since May 2001. The first 6 months of membrane testing was a component of the CHMFP membrane procurement and the performance data was used in the bid evaluation process. After the contract was awarded, the selected membrane supplier, Ionics, retained the pilot equipment onsite for the continuation of the long-term membrane testing program. This testing program is intended to last until the completion of the construction of CHMFP in 2006. The primary objective of this program is to evaluate the variability of membrane performance at different water quality conditions over the course of four years. Various operational issues, such as cold temperature production, flexibility and the optimization of membrane cleaning regime, are also scheduled to be investigated in this project. This paper focuses on the abrupt, excessive membrane fouling phenomena observed during spring-runoff seasons. Although the membrane permeability during the excessive fouling event was still higher than what the CHMFP is designed for, it was important for MWW to understand the nature of this unusual type of fouling. Also, identifying effective cleaning or preventive measures that can be used to handle such an event in the full-scale plant is highly desirable. Substantial collaborative efforts from the owner (MWW), consulting engineers (HDR/MP/SPI), and membrane provider (Ionics/Norit) were incorporated into the extensive studies on fouling identification and membrane permeability recovery approach. Includes tables, figures.