[Chinese Mainland] Zero Liquid Discharge for Desulfurization Wastewater Wins First Prize at CEC Power Innovation Awards: "Seed Crystal Scale Inhibition + Waste Heat Utilization" Pathway Achieves 75%–90% Wastewater Recovery Rate, with Operating Costs Reduc

9月8日, the China Electricity Council announced the list of winners of the 2026年 Electric Power Innovation Award. The complete set of technology for full-load zero liquid discharge of desulfurization wastewater based on seed crystal scale inhibition and waste heat utilization, completed by Datang Environment Industry Group Co., Ltd. in collaboration with Tianjin University of Science and Technology, Southeast University, and Datang Yan'an Power Generation Co., Ltd., won the First Prize for Technological Achievements. Application of this technology in multiple 660MW to 1000MW-level units shows: wastewater recovery rate 75%—90%, overall operating cost reduced to 20—30元/ton, a decrease of over 60% compared with traditional routes.

Desulfurization wastewater from coal-fired power plants has long been called the "toughest nut to crack" in coal power environmental protection. It is high in salinity, high in suspended solids, and contains heavy metals, with complex treatment routes and high costs. Moreover, after deep peak shaving of units became the norm, the traditional technical route gained another new problem—if the flue gas temperature is insufficient, the system has to shut down.

An award-winning achievement announced by 9月8日 provides a new solution to this difficult problem.

Three Cost Walls of the Traditional Route

To understand the value of this technology, one must first see clearly where the traditional route is expensive.

• High cost of chemical softening—the traditional route relies on complex chemical softening pretreatment, with chemical costs of about 40—50元/ton, while also generating sludge that must be disposed of as hazardous waste;
• High energy consumption of evaporation and crystallization—the terminal evaporation and crystallization stage has energy costs as high as 50—80元/ton;
• Poor peak-shaving adaptability—when units participate in deep peak shaving, the flue gas temperature is insufficient, and systems relying on flue gas waste heat frequently "shut down," making the actual operating rate difficult to guarantee.

The superposition of these three walls has made zero liquid discharge of desulfurization wastewater a showcase project that many power plants "can afford to build but cannot afford to operate." Especially under the new power system, coal-fired units increasingly undertake peak-shaving tasks, and load fluctuations have become the norm, imposing hard requirements on the full-load adaptability of zero liquid discharge systems.

Triple Innovation: Seed Crystal, Waste Heat, and Full-Load Coupling

The core of the award-winning complete set of technology is the reconstruction of the technical logic of zero liquid discharge of desulfurization wastewater through the triple innovation of "seed crystal scale inhibition + waste heat utilization + full-load coupling."

### Using Natural Gypsum in Wastewater as Seed Crystal

This technology uses the naturally present gypsum in desulfurization wastewater as a seed crystal. By directionally regulating the particle size and concentration of the seed crystal, scaling ions are made to precipitate directionally on the surface of the seed crystal, rather than crystallizing on the heat exchange surface. This change brings three direct effects: no cleaning required for the heat exchange surface, no hazardous waste generation, and no pretreatment required.

Turning scaling from "an accident to be guarded against" into "a controllable crystallization process" is the most ingenious part of this technology. Traditional chemical softening essentially uses chemicals to precipitate scaling ions in advance, at the cost of chemical fees and hazardous waste sludge; the seed crystal route, by contrast, utilizes the components of the wastewater itself and guides the precipitation process to the surface of the seed crystal, eliminating the two cost lines of chemicals and sludge.

### Using Low-Temperature Flue Gas Waste Heat to Drive Flash Evaporation

In terms of heat source, the technology uses low-temperature flue gas waste heat to generate 90—95℃ saturated steam to drive flash evaporation, replacing traditional auxiliary steam. According to public data, concentrating 1 tons of water can reduce coal consumption by about 50—60 kilograms.

This change also improves the energy consumption structure: flue gas waste heat was originally low-grade waste heat, and using it to produce 90—95℃ saturated steam exactly matches the flash evaporation demand, saving high-grade steam while also reducing the overall coal consumption of the power plant.

### Stable Operation Across the Full-Load Range

Through the heat source decoupling design of "low-temperature flash evaporation + rotary atomization drying," the system operates stably across the 30%—100% full-load range, truly adapting to the deep peak-shaving needs of the new power system.

Heat source decoupling is the key—after separately configuring the heat sources for the evaporation and concentration stage and the drying stage, the impact of unit load changes on the system is weakened, which also directly addresses the pain point of the traditional route "shutting down" during peak shaving.

From Yan'an Power Plant Demonstration to Multi-Unit Verification

This technology has not remained in the laboratory. According to public information, Datang Environment has assembled a cross-university, cross-disciplinary R&D team since 2022年, working with Tianjin University of Science and Technology and Southeast University to deeply study the mechanism of seed crystal scale inhibition, and implemented the first full-process demonstration at Datang Yan'an Power Generation Co., Ltd..

2024年7月, the system was commissioned in one pass, with a wastewater reduction rate exceeding 85% and a condensate reuse rate exceeding 90%.

Subsequently, applications in multiple 660MW to 1000MW class units showed:

• Wastewater recovery rate — 75%–90%;
• Overall operating cost — reduced to 20–30元/ton;
• Cost reduction — over 60% lower than conventional routes.

Upon appraisal, the technology was deemed to have reached the internationally leading level as a whole.

What 20–30元/ton Means

Putting the three figures in the same table makes the cost changes clear at a glance:

| Item | Conventional Route | Award-Winning Technology |

|---|---|---|

| Chemical cost | 40–50元/ton (dosing and softening) | No pretreatment, no hazardous waste |

| Evaporative crystallization energy consumption | 50–80元/ton | Replaced by waste heat-driven flash evaporation |

| Overall operating cost | On the order of approximately 50–130元/ton | 20–30元/ton |

For a million-kilowatt-class unit, although the desulfurization wastewater volume is not particularly large, calculated at an operating cost of 20–30元/ton, the long-term operating cost savings are considerable. More importantly, the cost reduction makes "real operation" possible — ZLD facilities are no longer decorations to pass inspections, but sustainable environmental assets.

The social significance also extends beyond the facility itself: blocking high-salinity and heavy metal discharge at the source eliminates risks to surrounding water bodies and soil; after flue gas waste heat replaces auxiliary steam, the annual coal consumption reduction for a single plant is considerable, equivalent to forming carbon dioxide emission reductions; units can participate more flexibly in grid peak shaving, also freeing up regulation space for high-proportion renewable energy integration.

Transferable Value for Other High-Salinity Wastewater Scenarios

Although this achievement targets desulfurization wastewater, its technical approach has reference significance for broader high-salinity wastewater treatment.

• The seed crystal approach is transferable — for any high-salinity wastewater with scaling tendency (coal chemical concentrated brine, mine water, some industrial wastewater), the route of "guided crystallization" rather than "chemical softening" can be considered, provided that usable seed crystal components exist in the wastewater;
• Low-grade heat sources are worth tapping — many industrial parks have substantial low-grade waste heat; if it can match the temperature requirements of evaporative concentration, it will significantly improve the energy consumption economics of ZLD processes;
• Full-load adaptability is a hard indicator — in an era when electricity load fluctuations and production condition fluctuations have become the norm, whether the treatment system can operate stably within the 30%–100% load range should become a mandatory question in scheme review.

What It Means for Us: TIANYI TECH's Assessment

TIANYI TECH has long served municipal and industrial park wastewater treatment and Reclaimed Water Reuse clients. In light of this award-winning achievement, we recommend that clients focus on three points when advancing high-salinity wastewater ZLD projects: first, conduct water quality component analysis to determine whether usable natural seed crystals exist, and evaluate the feasibility of "guided crystallization" replacing "chemical softening"; second, systematically sort out low-grade waste heat resources within the plant, treating heat source matching as a constraint for process selection rather than a post-hoc optimization item; third, incorporate the load fluctuation range into the design input, requiring suppliers to specify guaranteed operating values for the 30%–100% load range. The cost ceiling of ZLD is often raised in these three areas.

About TIANYI LIMITED: TIANYI LIMITED is deeply engaged in the field of wastewater treatment and Reclaimed Water Reuse, committed to providing efficient, low-carbon, and sustainable water treatment solutions for municipal and industrial clients.