Integrated Membrane Operations in Difficult Waters, Commercial Case Studies of UF + RO in China

Two commercial case studies are presented utilizing integrated membrane operations (UF +RO) for difficult waters in Northern China. WangTan Power Plant produces up to 7,200 m3/day of water for their power plant process water. This is a seawater desalination project. Almost 2.5 years of operating experience demonstrated long term reliable operation of the UF +RO system. Clean in place (CIP) was only required every 4-12 months. Tai Steel reuses internal waste water to produce 33,000 m3/day of water for both the boiler make-up of the power plant and for the steel production process. The waste water is highly challenging resulting in frequent CIP operations. More than two CIP operations per month were required to maintain stable RO operations. Root cause analysis determined that the SDI of the UF permeate was low enough to not be a source of RO fouling. Autopsy analysis of the first pass RO modules revealed both high inorganic fouling and high biofouling. It was shown that the antiscalant feed tank was the source of biofouling. It was also shown that improper Poly-Aluminum (PAC) coagulant dosing and improper antiscalant dosing were responsible for inorganic contamination. Adjustment of operating conditions resulted in a reduction of the more than 2 CIPs per month to 1 CIP per month.