Online analysis of cadmium in incineration plant wet gas scrubbers

Importance of the Topic

Incineration of municipal solid waste is an efficient way to reduce waste volume and recover energy, but it produces flue gas containing toxic heavy metals. Control of cadmium, zinc and lead emissions through wet scrubbing is critical for environmental protection and regulatory compliance. Continuous monitoring of scrubber effluent helps prevent breaches of discharge limits and supports operational decision-making.

Objectives and Overview

This application note demonstrates the use of an online voltammetric analyzer to track cadmium in the wastewater from wet gas scrubbers at incineration plants. The goal is to illustrate how the 2060 VA Process Analyzer delivers hourly metal concentrations, issues real-time alarms before limit exceedances, and enables timely corrective actions such as ion exchanger regeneration.

Methodology

The 2060 VA Process Analyzer employs anodic stripping voltammetry (ASV) using a glassy carbon electrode coated with a mercury film. The system automates sample intake, deposition of metal on the electrode, stripping, and data evaluation. ASV offers high sensitivity and can handle variable matrices, including saline or particulate-laden scrubber water. Key parameters monitored include:

• Cadmium at 1–30 μg/L
• Zinc at 1–80 μg/L
• Lead at 1–30 μg/L

Použitá instrumentace

2060 VA Process Analyzer: fully automated online analyzer for heavy-metal voltammetry with integrated pumps, dosing units and alarm capability.

Main Results and Discussion

The analyzer delivers hourly quantification of cadmium, zinc and lead in scrubber effluent. Real-time data reveal fluctuation in metal loads linked to ion-exchanger capacity and feed composition. The built-in alarm threshold warns plant operators before discharge limits are exceeded, enabling timely interventions and ensuring continuous compliance.

Benefits and Practical Application

• Guarantees adherence to stringent wastewater discharge regulations.
• Reduces downtime by signaling out-of-specification values promptly.
• Optimizes ion exchanger regeneration schedules, reducing chemical and maintenance costs.
• Provides 24/7 process data without reliance on intermittent laboratory tests.

Future Trends and Potential Uses

Advances in electrochemical sensor materials and miniaturization could further enhance online metals monitoring. Integration with plant control systems and cloud-based analytics may deliver predictive maintenance and tailored treatment strategies. The approach is extendable to other combustion processes, such as coal-fired power stations, and to additional contaminants.

Conclusion

The deployment of the 2060 VA Process Analyzer for online cadmium monitoring in wet gas scrubber effluent strengthens continuous compliance, improves process control and reduces operational costs. Its automated voltammetric detection and alarm functions offer real-time insights that laboratory methods cannot match.

Reference

1. Phua, Z.; Giannis, A.; Dong, Z.-L.; et al. Characteristics of Incineration Ash for Sustainable Treatment and Reutilization. Environ Sci Pollut Res 2019, 26 (17), 16974–16997. DOI: 10.1007/s11356-019-05217-8.