| 英文摘要 |
Solid Recovered Fuel (SRF) can reduce the demand for landfill space while lowering the use of fossil fuels, thereby reducing greenhouse gas emissions. However, due to the complex composition of SRF, its combustion process may generate harmful pollutants that pose environmental risks. Therefore, the objective of this project is to investigate pollutant emissions from SRF utilization sites and conduct environmental risk assessments.
As of November 2024, there are a total of 22 domestic facilities with stationary pollution sources permitted for either the "establishment" or "operation and fuel use" of SRF/RDF as fuel. The total maximum permitted usage of SRF/RDF is approximately 1.96 million metric tons per year. In 2023, the reported production volume of SRF-related products in the country was approximately 290,000 metric tons, accounting for 15% of the maximum permitted usage.
Among the 16 SRF-utilizing facilities that had obtained permits and were operating normally earlier this year, this project completed pollutant emission investigations for 5 facilities across 7 sessions last year (2023). This year, investigations for the remaining 11 facilities across 12 sessions were completed. The analysis covered emissions in the flue gases, waste (fly ash and bottom ash), and effluent. Pollutants tested included persistent organic pollutants (PCDD/Fs), polycyclic aromatic hydrocarbons (PAHs), heavy metals, PSN (particulate matter, sulfur dioxide, and nitrogen oxides), and plasticizers.
Additionally, 27 samples of alternative fuels and raw materials were collected for analysis of elemental composition, heavy metals, and plasticizer content. All tested items under the Ministry of Environment’s Solid Recovered Fuel Quality Standards (Cl, Pb, and Cd) met the required criteria.
During the pollutant emission investigations, three SRF-utilizing facilities were found to have PCDD/Fs concentrations in the flue gases exceeding standards. The SRF fuel used at these facilities exhibited higher Cu content than others, with Cu known to act as a catalyst for the low-temperature re-synthesis of PCDD/Fs. Moreover, one facility recorded higher emissions during the sampling period due to instability in the startup phase.
Among waste samples, only one facility exceeded the PCDD/Fs concentration limit in its fly ash. This was attributed to a high co-combustion ratio of SRF (86.2%) and the highest Cu content in the fly ash. An analysis of PCDD/Fs emission factors revealed a positive correlation between PCDD/Fs concentrations and Cl content in SRF or alternative fuels, as well as Cu content in fly ash.
For PSN concentrations in the flues (including particulate matter, SO₂, and NOₓ), only one facility recorded SO₂ levels exceeding the standards. This was due to the use of high-sulfur waste rubber as alternative fuel and an inefficient dry desulfurization process. All other pollutions in the flue gases, waste, and effluent samples complied with current emission standards.
This project uses AERMOD to simulate the dispersion and deposition of pollutants such as PCDD/Fs, PAHs, and heavy metals from SRF-utilizing facilities in areas like Taichung and Yunlin, serving as the basis for environmental risk assessments. After collecting and comparing environmental risk assessment models from Europe, the U.S., and Japan, this project found that these models all require the use of built-in parameters, which are specific to the environmental characteristics of Europe and the U.S. In contrast, California's multimedia model allows for the incorporation of Taiwan's local environmental parameters and uses Monte Carlo analysis to reduce uncertainty. Currently, based on Tier 1 environmental risk estimation, the hazard quotients (RQ values) for different chemical species (PCDD/Fs, PAHs, heavy metals) in various media (soil, water, sediment) across different facilities are all less than 1. This indicates that there is no immediate need for ecological risk assessment.
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