Dow's dual-membrane technology enables blow down water reuse in China power plant

For the past 40 years, the Gaojing Power Plant has supplied heat and electricity to its local communities and industries. Facing increased environmental regulations from the Chinese government in recent years, the plant enlisted Dow Ultrafiltration modules and Dow Filmtec brackish water reverse osmosis elements as a solution for reuse using the blow down from their cooling towers as boiler feed water.

"Water recycling systems for cooling tower blow down have become more common in fossil fuel power plants because of the large volume of wastewater needed," said Kelvin Cheung, strategic marking manager for Dow Water & Process Solutions. "Coupled with the proper pretreatment and chemical dosing, Dow Ultrafiltration modules and Filmtec membranes help eliminate problems in subsequent wastewater reuse systems."

Located in Mengtougou and constructed in the 1960s, Gaijing is one of the earliest power plants built by Datang Corporation in Beijing. Traditionally, the source of the cooling tower makeup was from surface water, but was changed to secondary effluent from the Gaobeidian Municipal Wastewater Treatment Plant in 2007. Due to the wastewater's concentration, contaminants varied substantially with seasons and cooling tower makeup quality.

Dow Water & Process Solutions' dual-membrane technology was able to overcome a waste stream containing high hardness, alkalinity, silicon dioxide and sulfate, typical in cooling water blow down to help the power plant meet government requirements. The integrated technology helped the plant realise more than 70 per cent reuse of the cooling tower blow down-even after five years of operation. This dual-membrane solution consists of Dow Ultrafiltration SFP-2660 and Dow Filmtec BW30-365FR and BW30-400 reverse osmosis membranes.