Review of Ice Slurry Pigging Techniques for the Water Supply Engineering Design and Application

It has been established that treated water can be easily impacted when delivered through drinking water distribution systems (DWDS), with issues such as discoloration, metal ion release, and bacterial regrowth. As part of good practice, water companies should take reasonable steps to prevent contamination from DWDS. Because traditional maintenance strategies have limitations, ice pigging can be employed as a powerful pipeline cleaning technique with the advantages of high cleaning efficiency, environmentally friendliness, not sticking, and cost effectiveness in some scenarios. This study aims to provide a review of the state-ofthe-art techniques of ice pigging for the water supply industry. After providing the mechanism of ice pigging, the generation and storage of ice slurries and ice fraction measurement were investigated. The critical aspects during the ice pigging process concerning the flow pattern, pressure drop, and survival distance of ice slurries were also discussed. In addition, this critical review integrated scattered knowledge on engineering design to improve the performance of ice pigging. Three important factors in practical engineering include ice slurry flow velocity, ice fraction, and ice pig length. Finally, informed by in-depth analysis of suitable applications and underlying mechanisms, ice pigging is expected to further enhance fouling removal capacity and enable better water quality, reduced service interruptions, and have fewer customer complaints.