Preliminary Emission Air Quality & TEQ Analysis

2026-02-15

Stack Gas Measurements, Oxidation Behavior, and Reference Comparison

Original publication: 15 February 2026
Technical revision: 11 October 2026

Introduction

This technical note reviews emission air quality measurements obtained during field operation of a gas-phase thermal oxidation process developed for Synthetic Polymer Compound Waste (SPCW).

The assessment draws on three emission analysis reports, including measurements conducted by SGS in Thailand, and considers additional field-testing experience in Korea.

The purpose is to distinguish measured emission concentrations from technical interpretations, evaluate preliminary Dioxin/Furan (TEQ) results, and provide context through publicly available data from conventional Waste-to-Energy (WtE) facilities.

The findings represent specific operating and sampling conditions. They do not constitute regulatory certification or a demonstration of long-term emission compliance.

1. Operating Conditions and Combustion State

The reported stack gas measurements include:

The residual oxygen concentration indicates operation under excess-air conditions during the sampling period.

The presence of CO₂ confirms carbon oxidation, while the reported zero opacity indicates an absence of measurable visible plume opacity under the test conditions.

However, oxygen concentration and opacity alone cannot establish complete combustion. Carbon monoxide (CO), total organic carbon (TOC), operating temperature, and residence-time information are also relevant to a comprehensive assessment.

The reported stack temperature represents the temperature at the sampling location and should not be interpreted as the peak temperature within the oxidation chamber.

2. Conventional Air Pollutants

The reported measurements include:

These results indicate relatively low measured concentrations of several conventional pollutants during the sampled operation.

The low NOx concentration is noteworthy, but it cannot independently establish a low peak flame temperature. NOx formation depends on multiple factors, including local temperature, oxygen availability, nitrogen-containing feedstock, and gas residence time.

Similarly, low particulate concentration and zero opacity provide favorable evidence concerning particulate emissions, but they do not independently demonstrate the absence of gaseous products of incomplete oxidation.

Regulatory comparisons require confirmation of the applicable emission limits, dry-gas basis, oxygen correction, sampling methods, and averaging periods.

3. Heavy Metals

Selected reported heavy-metal concentrations were:

These measurements indicate low or non-detectable concentrations for the selected metals under the reported conditions.

A non-detect result means that the substance was below the applicable analytical detection or reporting limit. It does not establish absolute absence.

Heavy-metal emissions may vary with waste composition, metal content, temperature, and particulate behavior. The available results should therefore not be generalized to all SPCW feedstocks.

4. Dioxins and Furans — Preliminary TEQ Assessment

Dioxins and furans are evaluated using Toxic Equivalency (TEQ), which weights individual congeners according to their relative toxic potency.

The SGS Thailand analysis provides the following reference result:

The oxygen-reference conversion is calculated using:

C(ref) = C(measured) × (21 − O₂ ref) / (21 − O₂ measured basis)

Therefore:

0.0332 × (21 − 11) / (21 − 7) = 0.0237 ng-TEQ/Nm³

The 11% O₂ value is a calculated equivalent, not a separate laboratory measurement. It assumes that the reported 7% O₂ concentration is already expressed on the relevant reference basis.

The previously published preliminary value of 0.00229 ng-TEQ/Nm³ has been excluded from the principal results pending verification of its original calculation basis.

The TEQ results require careful interpretation. Comparisons must account for the toxicity equivalency scheme (such as I-TEQ or WHO-TEQ), oxygen reference, dry-gas basis, analytical treatment of non-detected congeners, and sampling conditions.

The measurements provide evidence of low TEQ concentrations during the sampled operation but do not establish consistently low dioxin and furan emissions across all operating conditions.

5. Reference Comparison — Conventional Waste-to-Energy Facilities

Public emission-monitoring records from UK Waste-to-Energy facilities provide useful external context.

For example, Kent Enviropower publishes periodic Dioxin/Furan monitoring results expressed as percentages of its applicable emission limit.

Selected results for Line 1 include:

These percentages are the operator’s published results, not directly reported TEQ concentrations.

Using a reference limit of 0.1 ng I-TEQ/Nm³, the corresponding arithmetic equivalents would range from approximately 0.006 to 0.0916 ng I-TEQ/Nm³ for the selected observations.

This conversion is illustrative and must not be treated as an independently verified reconstruction of the original laboratory results.

The SGS Thailand result of approximately 0.0237 ng-TEQ/Nm³ at an 11% oxygen reference lies within the numerical range of these selected WtE reference values.

However, this does not establish equivalent environmental performance.

Conventional WtE facilities commonly employ dedicated flue-gas cleaning systems, while the reported AZADrg field configuration did not use a downstream scrubber or comparable pollution-control train. The test arrangement included heat exchange for sampling-equipment protection.

Differences in waste composition, treatment capacity, sampling duration, pollution-control systems, TEQ methodology, and operating conditions prevent a direct performance ranking.

The comparison demonstrates that publicly available industrial emission data can provide useful context for further technical investigation.

6. Interpretation of the Oxidation Process

The available measurements may be considered under three distinct categories.

Combustion State

Residual oxygen, CO₂ formation, low reported particulate concentrations, and zero opacity are consistent with an excess-air gas-phase oxidation regime during the sampled operation.

These indicators support the interpretation of controlled oxidation behavior, although complete combustion requires additional evidence.

Thermal Behavior

The measured NOx concentration was relatively low during the sampling period.

However, NOx alone cannot determine the peak oxidation temperature or characterize the full thermal history of the gas stream.

Chamber-temperature measurements, gas residence time, and temperature distribution are needed for a more complete assessment.

Toxicity Indicators

The reported Dioxin/Furan TEQ, selected heavy metals, and acid-gas concentrations provide preliminary evidence concerning the emission profile under the tested conditions.

These are emission indicators, not a complete assessment of environmental or human-health risk.

7. Process Configuration and Field Experience

The AZADrg approach is based on controlled formation and completion of a self-sustained oxidation flow (SSOF) within a staged gas-phase oxidation architecture.

The field configuration is intended to promote oxidation through controlled air distribution rather than relying on a conventional secondary combustion chamber.

Field trials in Thailand and Korea have contributed operational observations under different waste-loading and operating conditions.

The Korean field experience included extended operation with heterogeneous waste materials. However, the available information does not establish a directly comparable emissions dataset for every operating condition.

The Thailand emission results therefore remain the principal quantitative reference discussed in this note.

The absence of a downstream scrubber in the reported test configuration is an important engineering characteristic, but it does not remove the need for emission-control evaluation or compliance with applicable environmental regulations.

8. Limitations and Further Validation

The present assessment is preliminary for several reasons:

• Measurements represent specific sampling periods rather than continuous long-term monitoring.
• Waste composition and operating conditions may vary substantially between applications.
• The relationship between chamber temperature, gas residence time, and emission formation has not been comprehensively established.
• Additional verification of TEQ calculation conventions and reference conditions is required.
• Startup, shutdown, abnormal feeding, and transient operating conditions require further evaluation.
• Repeated independent sampling is necessary before drawing conclusions about reproducibility and regulatory compliance.

Future testing should include representative SPCW feedstocks, documented operating conditions, repeated Dioxin/Furan sampling, and comprehensive measurement of conventional pollutants.

Conclusion

The available field measurements provide encouraging preliminary evidence of controlled gas-phase oxidation and relatively low concentrations of selected air pollutants during the tested operating conditions.

The SGS Thailand Dioxin/Furan result of 0.0332 ng-TEQ/Nm³ at 7% O₂, equivalent by calculation to approximately 0.0237 ng-TEQ/Nm³ at 11% O₂, is a useful reference point for further technical evaluation.

Selected publicly reported UK WtE measurements provide comparative context, but the available evidence does not justify a claim of superior or equivalent overall emission performance.

The principal significance of these findings lies in the opportunity to investigate a comparatively simple gas-phase thermal oxidation architecture under independently measured operating conditions.

The next objective is not to claim universal performance, but to establish reproducibility through transparent measurement and field validation.

References and Data Sources

1. SGS Thailand — Stack Gas Emission Analysis and Dioxin/Furan TEQ reports, AZADrg field-test records.
2. Kent Enviropower — Public Emissions Monitoring Reports: https://kentenviropower.fccenvironment.co.uk/emissions-reports/
3. UK Environment Agency — Incinerator Annual Monitoring Reporting: https://environment.data.gov.uk/dataset/3500ab14-6546-45cf-acb2-c2a40e350737

Note: The numerical comparisons presented here are for technical reference only. They are not regulatory equivalence assessments or certifications of environmental performance.