TOC and TN Measurements of Wastewater

Importance of Total Organic Carbon (TOC) and Total Nitrogen (TN) Analysis

Monitoring TOC provides a direct measure of organic pollutants and reflects the overall degree of water contamination. TN assessment is crucial for preventing eutrophication and ensuring that effluent discharges meet environmental regulations. Reliable TOC and TN data support optimized operation of wastewater treatment facilities and protect receiving water bodies.

Objectives and Article Overview

This study demonstrates simultaneous determination of TOC and TN in wastewater from a metal plating plant before and after precipitation treatment. The goal is to highlight a rapid, reagent-free analytical approach and evaluate its performance for routine process control and environmental compliance.

Methodology

Samples of raw and treated wastewater were acidified and sparged for TOC analysis using a catalytic oxidation technique. Calibration for TOC employed 0 and 5 mgC/L standards of potassium hydrogen phthalate. TN was measured via thermal decomposition followed by chemiluminescence detection, with calibration based on 0 and 30 mgN/L potassium nitrate solutions. Both calibration curves were shifted to pass through the origin to correct for background carbon and nitrogen in ultrapure water.

Used Instrumentation

• Shimadzu TOC-LCPH total organic carbon analyzer
• TNM-L total nitrogen unit
• TOC/TN platinum catalyst
• Automatic sample dilution function for high-strength wastewater

Main Results and Discussion

Measured values for the raw wastewater sample were 1.365 mgC/L (TOC) and 23.03 mgN/L (TN). After precipitation treatment, TOC dropped to 0.9746 mgC/L and TN to 5.120 mgN/L. These results demonstrate effective removal of organic carbon and nitrogen, confirming method accuracy and repeatability. The rapid analysis time (approximately five minutes per run) contrasts favorably with traditional digestion-based TN methods requiring hours of sample preparation.

Benefits and Practical Applications

• Fast, simultaneous TOC and TN determination without chemical digestion
• High precision and minimal matrix interference
• Automatic dilution reduces reagent consumption and maintenance
• Supports real-time monitoring and optimization of wastewater treatment plants

Future Trends and Potential Uses

Advances may include integration of online TOC/TN analyzers with plant control systems, coupling with additional sensors for multi-parameter water quality assessment, and the application of data analytics for predictive maintenance. Sustainable catalyst materials and expanded detection ranges will further broaden application scope.

Conclusion

The combined TOC-LCPH and TNM-L system provides a rapid, reliable, and environmentally friendly approach for monitoring organic and nitrogenous pollutants in industrial wastewater. Its ease of use and accuracy make it an invaluable tool for process control and regulatory compliance.