CUF retrofit: Results in quality, performance and savings

The Nanostone ceramic ultrafiltration (CUF) membranes installed at Zhejiang Hengyang Thermal Power Company are operating at twice the capacity of polymeric ultrafiltration (PUF). The plant has also achieved a 95% water recovery rate, and can go six months between cleaning-in-place (CIP) reliably.

Located in China’s Zhejiang province, Zhejiang Hengyang Thermal Power Company operates a coal-fired central steam and power plant producing 60MW of power and 200 tonnes per hour of stream. The plant, situated along the Haiyangtong River, uses the river water – first treated with a clarifier and sand filtration step – as a source for both cooling and boiler feed makeup water, but during high turbidity excursions, the downstream multi-media filtration (MMF), ultrafiltration (UF) and reverse osmosis (RO) systems both experienced issues.

Nanostone Water determined that both the MMF and polymeric ultrafiltration (PUF) system could be replaced with its CM-151 technology, streamlining operations for the customer. Due to a high flux rating for CM-151 in this application, Nanostone determined that only 50% of the 112 PUF modules would be required across four treatment trains to meet current and peak capacity.

With minor mechanical modifications, the piping connections were retrofitted to accommodate the ceramic ultrafiltration (CUF) membranes, then connected to the existing common pipe and valve set for each membrane train. All of the remaining parts of the existing PUF system were reused including the feed pumps, feed strainers, backwash pumps, and chemically enhanced backwash (CEB) system.

Implementing CM-151 into the treatment process also reduced the need for the polymer programme as the ceramic membrane system was able to create silt density index (SDI) below two consistently and reliably. In addition to significant chemical cost savings, an increase in recovery rates for the RO pre-treatment solution helped reduce backwash water generation by 50%. Furthermore, a reduced CEB frequency of 50% helped reduce additional operating expenses for the plant.

The full article is published on the latest edition of Water & Wastewater Asia Jul/Aug 2021 issue. To continue reading the article, click here.