Analysis of Sewage and Sewage Sludge by ICPE-9000

Significance of the Topic

Sewage treatment generates large volumes of wastewater and sludge that contain heavy metals. Monitoring these contaminants is essential to protect public health and the environment. Analytical methods that can accurately quantify a wide range of elements support regulatory compliance, landfill disposal decisions, and resource recovery strategies.

Objectives and Study Overview

This study demonstrates the use of the ICPE-9000 inductively coupled plasma emission spectrometer for simultaneous determination of trace and macro elements in sewage effluent and sludge ash. It aims to validate the method against ICP-MS results and illustrate the instrument’s flexibility across varying concentration levels.

Methodology

• Sample Preparation
  • Sewage effluent: Acid digestion with nitric and perchloric acids, hot-plate decomposition, internal standard addition (yttrium), final dilution with HCl to 10 mL.
  • Sludge ash: Nitric acid digestion of 10 g solidified sludge, hot-plate heating, yttrium as internal standard, dilution with HCl to 100 mL.
• Analytical Approach
  • Calibration curve with internal standard method.
  • Comparison with ICP-MS (Shimadzu ICPM-8500) for effluent quality control.

Instrumentation

• ICPE-9000 multitype ICP emission spectrometer
• RF power: 1.2 kW
• Plasma gas flow rate: 10 L/min; auxiliary gas: 0.6 L/min; carrier gas: 0.7 L/min
• Sample introduction: coaxial nebulizer and cyclone spray chamber
• Plasma torch: mini torch with axial and radial viewing options

Results and Discussion

The ICPE-9000 provided quantitative values for elements such as B, Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn in both matrices. Effluent concentrations closely matched those obtained by ICP-MS, with differences within acceptable limits (e.g., B: 0.083 mg/L vs. 0.084 mg/L). Sludge ash levels ranged from low mg/kg (Cd 2.4 mg/kg) to tens of thousands mg/kg (Fe 22,200 mg/kg). Spectral profiles illustrated clear peak separation at optimal wavelengths selected automatically by the instrument for each element and sample matrix.

Benefits and Practical Applications

• Single instrument analysis across a broad concentration range reduces equipment needs.
• Automatic wavelength selection simplifies method development for diverse samples.
• Reliable data support environmental monitoring, regulatory compliance, and sludge reuse initiatives.

Future Trends and Opportunities

Advances may include higher-throughput sample introduction systems, improved detection limits through enhanced plasma stability, and integration with automated data management platforms. Expanding multi-element capabilities to emerging contaminants will further broaden environmental and industrial applications.

Conclusion

The ICPE-9000 offers a versatile and accurate solution for determining heavy metals in sewage effluent and sludge ash. Its multi-view capability and automated wavelength selection enable comprehensive analysis from trace to high concentrations, aligning with environmental monitoring requirements and waste management practices.

References

1. Japan Sewage Works Association. Wastewater Examination Method, 1997.
2. Prime Minister's Ordinance No. 5. Criteria for Verification Concerning Industrial Wastes, 1973.
3. JIS K0102-2008. Testing Methods for Industrial Wastewater.