Guoneng Taishan Power Plant FGD Wastewater Zero Liquid Discharge System (40 m³/h, 7 Units)

The Guoneng Taishan Power Plant, owned by China Shenhua under the National Energy Investment Group, sits on Tonggu Bay in Taishan, Jiangmen, Guangdong. On 24 February 2025 its flue-gas desulfurization (FGD) wastewater zero liquid discharge (ZLD) system completed a 168-hour trial run and entered commercial service, ending liquid discharge from the whole station. According to the National Energy Investment Group newspaper, the system handles FGD wastewater from all seven units at a design rate of 40 tonnes per hour, among the largest such facilities in the industry. Background Wet FGD plants must continuously bleed gypsum slurry to keep absorber chemistry stable and chloride in check. The bleed stream is acidic and carries high suspended solids, heavy metals and chloride. Conventional three-tank treatment removes metals and adjusts pH but leaves dissolved salts in the water. Taishan chose a concentrate-then-dry route: water is recovered as vapour back into the plant's heat cycle, and the residual concentrate is evaporated to dryness, so no liquid outfall remains. Process Five subsystems — flash concentration, bypass duct drying, heat extraction, concentrate handling and chemical dosing — are built around low-temperature multi-effect flash evaporation. Instead of a dedicated boiler, the system draws steam from flue-gas heat exchangers ahead of the FGD units of No.6 and No.7 boilers, plus standby auxiliary steam, turning low-grade waste heat into evaporation duty and improving overall thermal efficiency. Pre-treated wastewater enters the multi-effect flash evaporator and is concentrated stage by stage under vacuum. The concentrate is pumped to a storage tank and then to the drying section, where hot flue gas in the bypass duct evaporates the remaining moisture. A May 2025 follow-up report put the maximum concentration ratio at 92%, with on-line automatic turndown between 50% and 90%, allowing the system to follow unit load and wastewater generation — important for plants that cycle deeply. Performance All subsystems ran stably through the trial period and met design parameters. The plant cites a small footprint, stable performance, simple operation, a high degree of automation and low maintenance cost. With the system in service, FGD wastewater is no longer discharged, water is recycled inside the plant, pressure on nearby water bodies is reduced, and the station gains a key building block for its zero-waste enterprise programme. For comparable coal plants, the value of the waste-heat flash concentration plus bypass duct drying route is that it consumes no high-grade steam and needs no large evaporation-crystallisation building, making it suitable for retrofits at operating units — particularly in coastal or water-scarce regions with tightening discharge limits. Not disclosed Capital cost, construction start, EPC contractor, concentrate solids content and the final fate of the salts are not given in public reporting and are not estimated here. Sources 1. National Energy Investment Group News, "Guangdong Taishan Power Plant FGD wastewater ZLD system commissioned", 5 March 2025, https://epaper.ceic.com/pc/content/202503/05/content_11619.html 2. Shenhua Energy News, same title, 4 March 2025, https://www.nybsweb.com/shny/20250304/mhtml/page_02_content_20250304003005.htm 3. Shenhua Energy News, photo caption, 28 February 2025, https://www.nybsweb.com/shny/20250228/html/content_20250228002002.htm 4. National Energy Investment Group News, "Building a zero-waste benchmark through technology", 12 May 2025, https://epaper.ceic.com/pc/content/202505/12/content_13472.html Image: the 168-hour trial run of No.2 drying tower on 24 February 2025, with the bypass flue-gas drying tower and concentrate tanks behind (in operation; source: Shenhua Energy News, photo by Guo Siying).