UF System Provides Pretreatment

3M Industrial Group - Membranes Business Unit

Ultrafiltration (UF) is commonly used as a pretreatment to reverse osmosis (RO) to ensure consistent and efficient operation. As Shandong Hongxin Chemicals Co. Ltd in China recently discovered, this reliability—along with enabling quick setup and installation times—helped them realize convenience and cost savings. Additionally, given the fluctuations in contamination levels of the water source, the selected UF modules continuously exceeded requirements.

In 2014, HWTT designed a 13,000 cu m/day UF system that was equipped with 120 Liqui-Flux W10 modules to provide pretreatment to RO. The water source for this project was the middle and lower reach of the Yellow River.

The system design consisted of a settling pool to lower total suspended solids, such as sludge and sand from the river.

Due to the presence of algae and other organic contaminants, the feed water to the UF is continuously conditioned with 2-ppm NaClO, which improved the filtration process. Finally, 100-μm disc filters are used to protect the UF capillary membrane from obstruction by large particles.

The reliable and robust design of the Liqui-Flux W10 UF modules permitted HWTT to install, preserve and ship the entire skid after testing was completed. This allowed the customer to shorten installation time by several weeks and save on construction and testing costs. A heat exchanger is used to maintain a certain minimum of water temperature in winter.

This UF system has been running since March 2014 without incident. The produced water continues to exceed the customer’s technical requirements with a silt density index of no more than 3 and turbidity of less than 0.2 ntu. The recovery yield exceeds 90%, and maintenance and service levels have also proven to be better than expectations.