Dioxin Abatement Strategies and Mass Balance at a Municipal Waste Management Plant

Abstract

Since the thermal management of municipal solid waste (MSW) is considered to be one of the major sources of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs), the purpose of this study was to show the results of a dioxin abatement program performed in the municipal waste incineration (MWI) plant of Tarragona (NE Spain). Previously, stack gas emission levels of PCDDs/PCDFs around 3.26 ng I-TEQ/Nm3 were determined when the gas-cleaning system consisted only of an electrostatic precipitator (ESP). Decreased levels, below 0.1 ng I-TEQ/ Nm3, were observed when a new air pollution control system was installed. This new system was improved by the injection of activated carbon, which helped to lower the levels of PCDDs/PCDFs to around 0.01 ng I-TEQ/Nm3. Considering the absence of a particular impact on herbages, soils, and ambient air around the plant, as reported in previous works, and the hypothesis that a modern installation could become a sink for dioxins instead of a source, a dioxin mass balance was evaluated. The study compared in a large-scale MWI plant the levels of PCDDs/PCDFs of all input and output contributors (MSW, ambient air, stack gas emission, fly ash, and slag) forming part of the inventory collected in various monitoring campaigns. The findings revealed a remarkable homogeneity in output values (between 1.19 and 2.62 ng I-TEQ/yr) in contrast to the large variability observed in input values. In the first sampling campaign, the dioxin content in MSW was around 64.15 ng I-TEQ/kg, and a negative balance of 7.68 g I-TEQ/yr was calculated. However, in the latest campaign, levels were about 2.36 ng I-TEQ/kg MSW, resulting in a positive balance of 2.28 g I-TEQ/yr.

Variations and factors that influence the formation of polychlorinated naphthalenes in cement kilns co-processing solid waste

“…It has previously been found that the technique used, residence time, and raw material composition influence the formation of organic compounds during thermal processes [16,26]. The gases and solid materials flow in opposite directions in cement kiln system, meaning that the performance in terms of PCN formation will be affected by many factors.…”

The influence of electrodialytic remediation on dioxin (PCDD/PCDF) levels in fly ash and air pollution control residues

“…Lower temperatures and consequent unstable combustion might result in the formation of products of incomplete combustion, which might be precursors for PCDD/PCDF [21]. Electrostatic precipitators represent a low cost technology, but one which might lead to the formation of PCDD/PCDF [22], especially in old MSW incinerators without control of the flue gas treatment temperature. MSW incinerators are divided into four broad classes [23] and their description and emission factors are shown in Table S2 (Supplementary material).…”

Field pilot study on emissions, formations and distributions of PCDD/Fs from cement kiln co-processing fly ash from municipal solid waste incinerations

“…However, at the same facility, the concentrations of PCDD/Fs in fly ash were still as high (10-100 ng I-TEQ g −1 ). Similarly, at a municipal solid waste incinerator (MSWI) in Spain, the stack gas emissions of PCDD/Fs were reduced to below 0.01 ng TEQ m −3 from 3.26 ng TEQ m −3 after installation of a new air pollution control system combined with injection of activated carbon [9]. However, in this case, the PCDD/F concentrations in fly ash samples remained around 0.5 ng TEQ g −1 or higher.…”

“…Filters and activated carbon have been used to reduce emissions of PCDD/Fs into the atmosphere from industrial thermal facilities, including waste incinerators [4][5][6][7][8][9]. These techniques are very effective, for example, the stack gas concentrations of PCDD/Fs were reduced from 194 ng International Toxic Equivalents (I-TEQ) m −3 to below 1.0 ng I-TEQ m −3 by injection of activated carbon and addition of a dual baghouse filter system in a kiln using the Waelz process [4].…”