The push for tighter fluoride discharge standards in industrial wastewater is reshaping how plants manage their effluent—and new research from Beijing University of Technology is offering a clearer path forward. In a study published in *Gongye shui chuli* (Industrial Water Treatment), LIU Yawen and the team at the College of Architecture and Civil Engineering have quantified how key properties of polyaluminum chloride (PACl) coagulants—specifically aluminum oxide content, basicity, dosage, pH, and aluminum speciation—directly influence fluoride removal efficiency. Their findings aren’t just academic; they point to practical levers that plant operators can adjust to meet stricter compliance targets without overhauling existing systems.
“What we found is that the basicity of PACl has a stronger effect on fluoride removal than the Al₂O₃ mass fraction,” LIU explained. “That’s significant because basicity can be fine-tuned during coagulant manufacturing, giving producers and plant managers a real handle on performance.” The study shows that when treating water with 10 mg/L of fluoride, using PACl with high basicity (75–89%) and a moderate Al₂O₃ content (28–35%), dosed at 600–700 mg/L, consistently brought effluent fluoride levels down to 1.28–1.40 mg/L—well within advanced treatment thresholds.
Energy-intensive industries like power generation, aluminum smelting, and semiconductor manufacturing face mounting pressure to reduce fluoride in wastewater due to tightening environmental regulations. Traditional lime precipitation, while effective, often produces large volumes of sludge and struggles to reach low fluoride concentrations. Coagulation with PACl, already a common step in water treatment, emerges as a scalable upgrade—especially when process parameters are optimized.
The research also highlights a nuanced relationship between pH and aluminum speciation. “At pH 7, the proportion of medium-polymeric aluminum (Alb) in the coagulant peaks,” LIU noted. “That form is particularly effective at binding fluoride ions.” The study found that within the optimal pH range of 6–8, fluoride removal efficiency rose as Alb increased and fell as low-polymeric aluminum (Ala) dominated. This suggests that operators could use real-time monitoring of aluminum speciation—not just pH—to dynamically adjust dosing and improve outcomes.
For plant managers, the implications are clear: small changes in coagulant chemistry and process control can yield outsized improvements in fluoride removal, potentially avoiding costly tertiary treatment steps. As industries transition toward circular water use and zero liquid discharge, such optimizations could become a cornerstone of compliance and sustainability strategies.
The work doesn’t just validate lab findings—it was verified using real industrial wastewater, confirming that the trends hold under field conditions. That practical validation, published in *Gongye shui chuli*, signals that the next wave of fluoride treatment innovation may come not from entirely new technologies, but from smarter use of existing ones.