Typical Municipal Solid Waste Incineration Research Articles

Evolution of physicochemical and leaching characteristics of municipal solid waste incineration fly ash in China under ultra-low emission standard

The physical and chemical characteristics of fly ash has changed significantly under ultra-low emission system and the current leaching system is no longer suitable for high alkalinity fly ash. This work investigated the pH values and evolution of physical and chemical characteristics of fly ash from 24 typical municipal solid waste incineration plants in China. The pH value of the leaching solution obtained by HJ/T 300–2007 presented two different acid and alkali characteristics, where high and low alkalinity fly ash accounted for 54.17% and 45.83%, respectively. The alkali content in fly ash increased significantly after ultra-low emission standard, increasing by 18.24% compared with before the implementation of GB 18485-2014. The leaching behavior of high alkalinity fly ash showed the illusion that they could enter the landfill only by the addition of a small amount of chelating agent or even without stabilization treatment, and its long-term landfill risk is significant. The phase change of high alkalinity fly ash and pH value change of the leaching solution after carbonation were the key factors for the leaching concentration change of heavy metals. Therefore, it is recommended to improve the existing leaching system or conduct accelerated carbonization experiments to scientifically evaluate the long-term leaching characteristics of high alkalinity fly ash, and to reduce the risk of heavy metal release from high alkalinity FA after entering the landfill site.

Exergy Profit Evaluation of Municipal Solid Waste Processing

This article evaluates the processing of Municipal Solid Waste (MSW) and its contribution to sustainability from the viewpoint of its net exergy balance. The evaluation follows the recent framework for estimation of Exergy Footprint and Exergy Profit for a given Process System. The method evaluates the Exergy Assets and Liabilities, estimating the Exergy Profit as the balance of these two. The concept of avoided exergy by substituting the useful chemical to its primary production, similar to the concept of avoided emission is also proposed in this work. The obtained estimate is the specific contribution of the considered MSW processing system. For estimating the overall impacts, the obtained Exergy Profit has to be added to the contributions of the potential upstream and downstream processes. The results show the potential value that can be obtained and sustainability contribution to be achieved by the extraction of useful chemicals from waste and waste-to-energy conversion. The chemical extraction option shows a marginally higher Exergy Profit compared with the typical MSW incineration practice, indicating that, as long as there is a sufficient market demand for the chemical products, this route can be more beneficial. An important outcome is that the product substitution can lead to three-fold increase in the Exergy Profit and the related emission savings.

Occurrence characteristics of microplastics and heavy metals in pyrolysis incineration residues of small towns in Southern China

Closed oxygen-limited pyrolysis is becoming a widely used waste treatment method in small towns. In the present study, we selected some typical municipal solid waste incineration plants in Jiangxi Province in Southern China as the research areas, and collected the ash samples which from the stacking ground after pyrolysis of refuse and its surrounding environment soil with ash slag and surface soil as the research materials. The flotation separation method, scanning electron microscopy method, ICP-MS and BCR three-step continuous extraction methods were used to study the abundances of microplastics and the occurrence characteristics of different forms of heavy metals such as Cu, Cd, Pb, Zn and Cr. The results showed that there were some differences in the abundance of microplastics in samples from different sources. The abundance range of microplastics in ash from different garbage factories was from 131.00 n·kg-1 dw to 176.00 n·kg-1 dw (the amount of microplastics in dry soil samples per kg), which was significantly higher than that in the soil with ash slag and surface soil in the surrounding environment. The morphological types of microplastics were mainly debris (38.5%) followed by film (17.6%), fiber (26.7%) and foam (17.2%). The main colors of microplastics were black (29.4%), white (12.2%), transparent (20.8%), blue (12.4%) and red (25.3%). The proportions of the microplastics abundances with different particle sizes were > 5 mm (11%), 2.5—5 mm (13%), 1—2.5 mm (19%), 0.5—1 mm (24.2%) and Cd (73.48%) > Zn (55.69%) > Cu (38.8%) > Cr (38.02%). The results of correlation analysis showed that the abundance of microplastics and the occurrence of heavy metals in pyrolysis residue of the garbage were corelated and the correlation between the content of heavy metals and microplastics with different characteristics was different. There was a significant correlation (P<0.05) between black microplastics and most heavy metal elements, and also between microplastics with particle size less than 0.5 mm and most heavy metal elements.

Spatial distribution and pollution evaluation of heavy metals in soils surrounding a typical municipal solid waste incineration plant in Hang-Jia-Hu plain

In this study, soil samples around the typical municipal solid waste incineration (MSWI) plant in Hangzhou-Jiaxing-Huzhou Plain were collected. The concentrations of heavy metals were determined using X-ray fluorescence spectrometry (XRF), atomic absorption spectrometry (AAS) and mercury analyser. Mean concentrations of Cr, Mn, Cu, Pb and Fe were 174, 708, 47.68, 41.95 and 39,058 mg/kg in this region, respectively. Principal component analysis and cultural enrichment factor (CEF) analysis showed that Cr, Mn and Fe were present as background origin in soils surrounding the incineration plant. Combined with historic land use information, the results showed that the application of pesticide with high content of Cu probably contributed to Cu distributions in the study region. The MSWI plant with high Pb emission from stack resulted in the Pb distribution patterns in surrounding soils. The study highlighted that MSWI could contribute to heavy metal accumulation in surrounding soil.

Spatial distribution and pollution evaluation of heavy metals in soils surrounding a typical municipal solid waste incineration plant in Hang-Jia-Hu plain

Spatial distribution and pollution evaluation of heavy metals in soils surrounding a typical municipal solid waste incineration plant in Hang-Jia-Hu plain

Mercury Emission Characteristics and Mercury Concentrations of Municipal Solid Waste in Waste Incineration Plants

Municipal solid waste (MSW) incineration is one of the most important atmospheric mercury emission sources. To investigate the mercury concentrations of MSW and mercury emission characteristics in incineration plants, this study analyzed the MSW sampled in 3 typical MSW incineration plants in Shanghai, Guangzhou and Wuhu respectively. The exhaust gas samples in incineration plants were sampled by using OH (Ontario Hydro) method. The mercury concentrations in fly ash, and bottom ash samples were also analyzed. The results indicated that mercury concentrations of MSW in Shanghai, Guangzhou, and Wuhu incineration plants were (0.39±0.04) mg·kg-1, (0.57±0.05) mg·kg-1, and (0.27±0.08) mg·kg-1 respectively. The mercury concentrations of exhaust gas in Guangzhou, Wuhu MSW incineration plants were (9.5±3.9) μg·m-3 and (24.1±6.0) μg·m-3 respectively; Particulate mercury (Hgp), gaseous oxidized mercury (Hg2+), and gaseous elemental mercury (Hg0) represented (0.9±0.8)%, (89.0±5.4)%, (10.1±4.6)% in Guangzhou MSW incineration plant, and (1.0±0.8)%, (65.4±27.6)%, (33.6±27.5)% in Wuhu MSW incineration plant, respectively. Gaseous oxidized mercury (Hg2+) of exhaust gas in different incineration process showed different distribution proportions. Besides, mercury removal efficiency of Guangzhou, Wuhu MWS incineration plants was 96.7% and 33.7%, respectively. The atmospheric mercury emission factors of Shanghai, Guangzhou, and Wuhu MSW incineration plants were (0.156±0.016) mg·kg-1, (0.019±0.002) mg·kg-1, (0.178±0.027) mg·kg-1 respectively. Compared with MSW incineration plants in Japan and Korea, the atmospheric mercury emission factor of Guangzhou incineration plant was slightly lower; Atmospheric mercury emission factors of Shanghai and Wuhu MSW incineration plants were close to those of domestic fractional MSW incineration plants.

Concentration and distribution of PCNs in ambient soil of a municipal solid waste incinerator

The impact of a typical municipal solid waste incinerator (MSWI) on polychlorinated naphthalene (PCN) concentrations in surrounding soil was studied. We collected 6 stack gas samples from the MSWI and 21 soil samples from sampling sites at distances of between 300 and 1700m from the MSWI stack. Total dl-PCN (dioxin-like PCN) concentrations in the stack gas samples ranged from 6898 and 89,032pgm−3, with a mean value of 36,241pgm−3. The total dl-PCN concentrations in the soil samples ranged from 30.35 to 280.9pgg−1, with a mean value of 87.03 and a median value of 70.32pgg−1, while the TEQ values were between 7.7 and 130.2fg TEQ g−1, with a mean value of 41.12fg TEQ g−1 and a median value of 31.52fg TEQ g−1. The PCN homologue patterns and the results of Principal Component Analysis suggested that the MSWI may be a source of PCNs in the soils. A contour map, created using an ordinary Kriging interpolation technique, showed that a limited area (≤1000m radius) surrounding the MSWI was influenced by the emissions from the MSWI. Furthermore, an exponential function equation was proposed to quantify the relationship between TEQs of PCNs and the distance from the stack.

Spatial distribution of polychlorinated biphenyls in soil around a municipal solid waste incinerator

The impact of a typical municipal solid waste incinerator (MSWI) on polychlorinated biphenyl (PCB) concentrations in the surrounding soil was studied. Six stack gas samples were taken from the MSWI and 21 soil samples were collected from sampling sites between 300 and 1700 m from the MSWI stack. The total (PCB) concentrations of dioxin-like (dl) PCBs and indicator PCBs in the stack gas samples were between 3.41 and 34.3 ng/m3, and the corresponding toxic equivalents (TEQs) ranged from 4.45 to 66.9 pg WHO-TEQ/m3, with a mean of 28.6 pg WHO-TEQ/m3. A total of 2.43 g WHO-TEQ of PCBs per year was calculated to be released into the environment from MSWIs in China. The PCB concentrations in the soil samples ranged from 28.0 to 264.4 pg/g, with mean and median values of 127.6 and 127.7 pg/g, respectively, while the TEQ values were between 0.020 and 0.18 pg WHO-TEQ/g, with mean and median values of 0.074 and 0.062 pg WHO-TEQ/g, respectively. Comparing this study with other studies performed around the world suggest that PCB emission from incinerators has a critical influence on PCB concentrations in the surrounding soil. An exponential function equation is proposed, which indicates a clear decline in PCB concentrations with increasing distance from the stack. A contour map created using an ordinary kriging interpolation technique showed that a limited area (≤ 1250 m radius) from the stack was clearly influenced by PCB emission from the MSWI.

Chemical characteristics and risk assessment of typical municipal solid waste incineration (MSWI) fly ash in China

The release of heavy metals in municipal solid waste incineration (MSWI) fly ash has become a worrying issue while fly ash is utilized or landfilled. This work investigated the potential mobility of heavy metals in the fly ashes from 15 typical MSWI plants in Chinese mainland by the characterization of distribution, chemical speciation and leaching behavior of heavy metals. The results showed that total content of heavy metals decreased in the order Zn>Pb>Cu>Cr>Ni>Cd in samples. The toxicity characteristics leaching procedure (TCLP) of fly ash indicated that the amount of leached Cd in 67% of samples exceeded the regulated limit. Also, the excess amount of leached Zn and Pb was observed in 40% and 53% of samples, respectively. The chemical speciation analysis revealed that this excess of heavy metal leached in TCLP was contributed to the high content of acid soluble fraction (F1) and reducible fraction (F2) of heavy metal. Moreover, the great positive relevance between leaching behavior of heavy metals and F1 fraction was supported by principal component analysis (PCA). Risk assessment code (RAC) results suggested that Cd and Pb showed a very high risk class to the environment.

Concentrations and Profiles of Polychlorinated Dibenzo-p-Dioxins and Dibenzofurans in Air and Soil Samples in the Proximity of a Municipal Solid Waste Incinerator Plant

This study investigated the influence of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in the waste gas from an incinerator on the surrounding environment. A series of air and soil samples were collected at distances from 1.35 to 4.72 km from a typical municipal solid waste incineration plant along the prevailing north wind direction. Concentrations of PCDD/Fs in the ambient air samples ranged from 0.23 to 1.66 pg I-toxic equivalent (TEQ)/m3, with an average of 0.82 pg I-TEQ/m3; while concentrations in the soil samples varied from 0.54 to 1.96 pg I-TEQ/g, with an average of 1.33 pg I-TEQ/g. Principal component analysis and hierarchical cluster analysis showed that the municipal solid waste incinerator has a potential influence on the environmental level of PCDD/Fs, and that emissions from traffic also play an important role.

MSWI flue gas two-stage dry treatment: Modeling and simulation

Power generation from Municipal Solid Waste incineration is widespread used as a technology for solid waste treatment and energy recovery. One of the main impacts of these plants is the continuous emission of pollutants into the atmosphere. Another issue to be addressed is the generation of solid or liquid residues from flue-gas cleaning, depending on the flue-gas treatment process.Among the substances produced during thermal incineration, acid gases are of particular interest because of their environmental impact. One of the most promising combination of Best Available Technologies for an enhanced removal efficiency of acid gases is the two-stage dry treatment. In the analysed process, solid powder of calcium hydroxide (slaked lime) is used in the first stage while in the second one sodium bicarbonate (more effective) is injected, allowing the decrease of pollutants concentration until the design values.In the present study an operational model (based on the ratio of reactant rate to stoichiometric rate) is proposed to fit literature data concerning the performance of the process considered. The implementation of the model in a simulation software has allowed describing the design conditions of a typical Municipal Solid Waste Incinerator (MSWI). Other simulations were carried out with the aim of reducing solid products formed by flue gas treatment without decreasing the removal efficiency. The model was also used to assess the possible cost optimization by the identification of optimal reactant feed rates.

Change in MSW characteristics under recent management strategies in Taiwan

Reduction and recycling initiatives such as producer responsibility and pay-as-you-throw are being implemented in Taiwan. This paper presents a study assessing the impact of recently implemented municipal solid waste (MSW) reduction and recycling management strategies on the characteristics of waste feedstock for incineration in Taiwan. Through the periodic sampling of two typical MSW incineration plants, proximate and ultimate analyses were conducted according to standard methods to explore the influence of MSW reduction and recycling management strategies on incineration feed waste characteristics. It was observed that the annual amount of MSW generated in 2005 decreased by about 10% compared to 2003 and that the characteristics of MSW have changed significantly due to recent management strategies. The heating value of the MSW generated in Taiwan increased yearly by about 5% after program implementation. A comparison of the monthly variations in chemical concentrations indicated that the chlorine content in MSW has changed. This change results from usage reduction of PVC plastic due to the recycling fund management (RFM) program, and the food waste as well as salt content reduction due to the total recycling for kitchen garbage program. This achievement will improve the reduction of dioxin emissions from MSW incineration. In summary, management strategies must be conducted in tandem with the global trend to achieve a zero-waste-discharge country. When implementing these strategies and planning for future MSW management systems, it is important to consider the changes that may occur in the composition and characteristics of MSW over time.

A Novel Energy-Efficient Process Utilizing Regenerative Burners for the Detoxification of Fly Ash

During the last decade, the debate concerning incineration has focused mainly on potential risks from air emissions. Today, waste incineration will only gain full public acceptance if a high quality of ash residues can be guaranteed, particularly with respect to low levels of organic compounds such as polychlorinated dibenzo- p -dioxins and polychlorinated dibenzofurans (PCDD/Fs) and the high elution stability of toxic heavy metals. Conventional thermal treatment techniques such as vitrification have been used in the past for detoxification of the ash residues from incinerators, but at a significantly high cost due to the massive energy consumption of the process. This paper addresses the problem of safe disposal of millions of tonnes of contaminated fly ash produced each year by developing an economically viable energy efficient process that can convert this toxic material into a non-toxic material. The decontaminated material can then be safely land-filled or used in construction applications such as in road foundations. This approach is based on the fact that sintering of the ash residue results in destruction of its toxic organic components, and also fixation of its heavy metal content. The novelty of the process includes the integration of the sintering process with the concept of regenerative heating. This is a very energy-efficient concept that results in typical fuel savings of 65% in industrial furnaces. A fully operational ash detoxifying pilot plant with a throughput suitable for continuous treatment of fly ash generated by a typical municipal solid waste incinerator plant was constructed and operated. An extensive series of analytical tests were carried out on both the raw and thermally treated ash samples. The results obtained showed an achievement of up to 96% reduction in the heavy metal leaching potential in the sintered ash. The sintering process de-volatilized metals having a high vapour pressure and effectively trapped other heavy metals in oxide sinters/melts. The reduction in leaching potential can be largely attributed to the formation of these stable oxides. This finding was verified by computational analysis that showed that up to 99.9% of some metals were converted into metal oxides during the sintering process. Analysis of the sintered ash samples/pellets for PCDD/Fs using standardized methods with GS-MS/MS equipment showed a major reduction in PCDD/Fs concentrations to below the detectable limit of 0.1 pg g − 1. These results are exceptionally encouraging since they eliminate the concern over the safety and suitability of the sintered ash material/pellets for re-use. Each cyclone was designed to provide enough residence time for the ash particles to be heated up to the sintering temperature of 850°C. High temperature conditionswere maintained throughout the cyclone thus helping to avoid any re-formation of toxic organic compounds such as PCDD/Fs. Detailed analysis showed that the use of heat regeneration in our sintering process provided significant energy and economic savings of up to 50%.

Assessment of the environmental impact of PCDD/Fs in the vicinity of a municipal waste incinerator: Congener profiles of PCDD/Fs in soil and vegetation samples

Municipal solid waste (MSW) incineration is a component of integrated waste management in many countries. Among typical MSW incinerator contaminants, polychlorinated dibenzo‐p‐dioxins (PCDDs) and dibenzofurans (PCDFs) are of especial concern. Measuring PCDD/F concentrations in soil and vegetation samples collected in the vicinity of a MSW incinerator can be a suitable method to determine the environmental impact of PCDD/F emissions from MSW incinerators. However, these concentrations can be increased by the presence of other emission sources of PCDD/Fs in the area under evaluation. In the present study, we have used PCDD/F congener profiles from soil and vegetation samples collected near an old MSW incinerator (Montcada, Barcelona, Spain) in 1996, 1997 and 1998 in order to estimate the direct contribution of the plant to the environmental levels of PCDD/Fs in the area under potential influence of the facility. PCDD/F congener profiles were compared with those from samples collected in the vicinity of another MSW incinerator, as well as with those from an area which is not under the direct influence of any MSW incinerator. From an accurate inspection of the PCDD/F congener profiles, it can be concluded that emissions of PCDD/Fs from the MSW incinerator of Montcada are neither the only nor the main responsible for the presence of these pollutants in soil and vegetation samples collected in the area under direct influence of the plant.