The coal-fired power industry faces pressing needs to improve disposal practices for the generated flue gas desulfurization (FGD) wastewater and coal fly ash (CFA). Zero-liquid-discharge (ZLD) strategies are gaining significant interest and can be achieved by co-disposing the concentrated FGD wastewater brine with CFA and Portland cement in a solidification/stabilization (S/S) process—a novel strategy that manages two wastes simultaneously. In this study, the stability of such S/S solids produced by utilizing bituminous CFA was evaluated for the mass transport release of major components (Ca²⁺, Cl⁻, Mg²⁺, Na⁺, and SO₄²⁻) and heavy metal oxyanions (As, Cr, and Se) in long-term leaching tests. Particularly, the impact of FeSO₄ (FS) addition to the S/S mixture for the purpose of enhancing heavy metal immobilization was assessed. Results showed that FS addition to the S/S process decreased the solid’s cumulative release and flux at shorter leaching times for the major components Ca²⁺, Cl⁻, Mg²⁺, Na⁺, and SO₄²⁻, but this effect was diminished over time. However, FS addition significantly decreased release of oxyanions As, Cr, and Se throughout the prolonged leaching time, indicating that FS addition could increase the likelihood of successful long-term disposal of S/S solids of concentrated FGD brines containing these heavy metal oxyanions. Results of this study can help the power industry to further assess and optimize the co-disposal ZLD strategy to minimize environmental risks.

燃煤电力行业面临着紧迫的需求，以改善对产生的烟道气脱硫（FGD）废水和粉煤灰（CFA）的处置方法。零液体排放（ZLD）策略引起了人们的极大兴趣，可以通过在固化/稳定化（S / S）过程中将浓缩的烟气脱硫废水与CFA和硅酸盐水泥共同处置来实现，这是一种管理两种废物的新颖策略同时。在这项研究中，例如S的稳定性/ S通过利用沥青CFA产生的固体被评价为主要成分（Ca的质量运输释放²⁺，氯^- ，镁²⁺，钠⁺和SO ₄ ^2-）和长期浸出试验中的重金属氧阴离子（As，Cr和Se）。特别地，评估了FeSO ₄（FS）添加到S / S混合物中对增强重金属固定化的影响。结果表明，FS除了S / S处理降低在更短的时间浸出固体的累积释放和通量的主要成分的Ca ²⁺，氯^- ，镁²⁺，钠⁺和SO ₄ ^2-，但是随着时间的流逝，这种影响逐渐减弱。但是，在整个浸出时间内，添加FS显着降低了氧阴离子As，Cr和Se的释放，这表明添加FS可能会增加长期成功处置含有这些重金属氧阴离子的浓缩FGD盐水中S / S固体的可能性。这项研究的结果可以帮助电力行业进一步评估和优化联合处置ZLD策略，以最大程度地降低环境风险。