Evaluation on speciation and removal efficiencies of mercury from municipal solid waste incinerators in Taiwan

Two large-scale municipal solid waste incinerators (MWIs) located in Taiwan were selected for conducting flue gas sampling to determine the chemical speciation of mercury by both USEPA Method 29 and Ontario Hydro Method (OHM). In addition, the emission characteristics and removal efficiencies of mercury were evaluated via isokinetic sampling of flue gas upstream and downstream of APCDs. Results indicated that the average removal efficiencies of Hg for MWI-A and MWI-B were 29.56 and 44.70%, respectively. In terms of mercury speciation by USEPA Method 29 and Ontario Hydro Method (OHM), oxidized mercury (Hg2+), in the flue gas was predominant at the inlet of APCD for both incinerators. Less than 30% of mercury in the flue gas existed in the elemental form (Hg0) at APCD inlet. Mercury emitted from the stack also predominated as a form of Hg2+ in MWI-A. Approximately 90% of total mercury emission from the stack existed in the form of Hg2+ for MWI-A. Due to the higher removal efficiency of soluble mercury (Hg2+) in wet scrubber, less total Hg was actually emitted from MWI-B than MWI-A. Regarding the removal efficiency of Hg0 in the flue gas, the APCDs of MWI-A (DSI + FF) had a higher removal efficiency than that of MWI-B (ESP + WS) possibly due to the reduction of Hg2+ which occurred in the wet scrubber.     

Spatial modelling of gaseous emissions from two municipal solid waste dump sites

This paper reports the spatial modelling of gaseous emissions from two municipal solid waste dump sites to determine exposure to landfill gases. The AERMOD modelling software and the Mexican Biogas Model were used, with information from nearby meteorological stations for the period 2015–2016. It was observed that, at one of the dump sites, gas emissions reach populated areas, but in concentrations too low to be detected by the olfactory pathway (benzene <5 µg/m³, toluene and xylene <50 µg/m³). At the second dump site, concentrations are greater; there are no population settlements close by. The highest concentrations of benzene, toluene, xylene and hydrogen sulphide are found within, or around, the dump sites, reaching levels greater than 38 μg/m³ for benzene, 770 μg/m³ for toluene and 237 μg/m³ for xylene.     

Regional development and climate change mitigation modelling of municipal solid waste emissions in the middle east

This study adapts a climate change mitigation model to assess impacts of municipal solid wastes in the Middle East and North Africa region, taking into account the future development of integrated waste management infrastructure involving collection, treatment and disposal. Mitigated and unmitigated disposal scenarios including waste growth reduction are used to estimate disposal methane emission changes at regional and subregional level. This study shows that unmitigated regional emissions by 2050 could rise to 296 542 GgCO_2eq from a current level in 2015 of 128 184 GgCO_2eq additionally decreasing annually by up to 8.75% falling to 10.16% due to waste characterisation changes as developing countries in the region progress to developed country status. A further annual rise, due to hotter drier climate conditions experienced as desertification, of up to a range of 1.70% increasing to 2.29% is also demonstrated. The findings enable regional planners to better assess and develop plans for implementation of integrated waste management policies.     

Evaluation and prediction of emissions from a road built with bottom ash from municipal solid waste incineration (MSWI)

In autumn 2001, a full-scale test road was built with municipal solid waste incineration (MSWI) bottom ash at the D?vamyran landfill, Ume?, Northern Sweden. Leachates were collected from asphalted sections with either bottom ash or gravel as filling material. In this research, 12 months of ash leachate sampling were evaluated with respect to emissions of contaminants such as trace metals and chlorides (Cl). The usefulness of regression models describing trace metal mobility from bottom ash was also tested as predictive tools for reusability applications of MSWI bottom ash. Cl, Cu, and Cr had the highest mobility (considering leachate concentrations) in the ash leachate, though concentrations of Cl and Cu decreased during the sampling period (Cl from 10,000 to 600 mg l(-1); Cu from 1600 to 500 microg l(-1)). An increased mobility of Cr during the autumns (about 3-4 times higher compared to the summer) was noted with a maximum value of nearly 70 microg l(-1) during autumn 2001. Pb showed a very low mobility over the entire year with leachate concentrations of around 3-4 microg l(-1). Chemical equilibrium calculations using Minteq indicated that several Cu minerals were oversaturated in the leachate, thus mineral precipitation could be responsible for declining amounts of Cu in the leachate. Adsorption to iron oxides was found to be a probable explanation for the low mobility of Pb. A reasonably good agreement between regression models and field values were achieved for Ni, Pb, Zn, and Cu, while the models for Cd and Cr were less promising. Even though a large part of the variation (R2=61-97%) in the leaching experiment could be explained by only pH and L/S, field data were much more scattered than expected from field pH.     

Life cycle assessment of municipal solid waste management with regard to greenhouse gas emissions: Case study of Tianjin, China

The environmental impacts of municipal solid waste (MSW) management have been highlighted in China, due to the continually increasing amount of MSW being generated and the limited capacity of waste treatment facilities. Of particular interest is greenhouse gas (GHG) mitigation, aided by the Kyoto Mechanisms. China is an important case study for this global issue; however, an analysis of the entire life cycle of MSW management on GHG emissions is not available for China. This study evaluates the current and possible patterns of MSW management with regard to GHG emissions, using life cycle assessment (LCA), based on the Tianjin case. We assess the baseline scenario, reflecting the existing MSW management system, as well as a set of alternative scenarios, five exploring waste treatment technology innovations and one exploring integrated MSW management, to quantitatively predict potentials of GHG mitigation for Tianjin. Additionally, a sensitivity analysis is used to investigate the influence of landfill gas (LFG) collection efficiency, recycling rate and methodological choice, especially allocation, on the outcomes. The results show GHG emissions from Tianjin's MSW management system amount to 467.34 Mg CO₂ eq. per year, based on the treatment of MSW collected in the central districts in 2006, and the key issue is LFG released. The integrated MSW management scenario, combining different improvement options, shows the highest GHG mitigation potential. Given the limited financial support and the current waste management practice in Tianjin, LFG utilization scenario would be the preferred choice. The sensitivity analysis of recycling rate shows an approximately linear relation of inverse proportion between recycling rate and total GHG emissions. Kitchen waste composting makes a considerable contribution to total GHG emissions reduction. Allocation choices result in differences in total quantitative outcomes, but preference orders and contributions analysis are found to be robust, suggesting LCA can support decision making.     

Burden of disease attributable to air pollutants from municipal solid waste incinerators in Seoul, Korea: a source-specific approach for environmental burden of disease

Few studies have attempted to quantify the integrated health burden, incorporating both mortality and morbidity as these factors pertain to air pollutants, on the population in the vicinity of the incinerators. The aims of this study are to estimate the attributable burden of disease caused by incinerators in Seoul, Korea and to present an approach based on source-specific exposure for the estimation of the environmental burden of disease (EBD). With particular attention on the development of a measurement means of the source-specific, exposure-based population attributable fraction (PAF), we integrated air dispersion modeling, Geographic Information Systems (GIS), the population distribution of exposure, and the exposure-response relationship. We then estimated the PAFs caused by additional concentrations of four air pollutants (PM₁₀, NO_2, SO₂, and CO) emitted from four municipal solid waste incinerators (MSWIs) in Seoul in 2007. We, finally, estimated the attributable burden of disease, using the estimated PAF and the disability-adjusted life years (DALY) method developed by the Global Burden of Disease Group of the World Health Organization (WHO).The PAF for NO₂ to all-cause mortality was assessed at approximately 0.02% (95% CI: 0.003-0.036%), which was the highest among all air pollutants. The PAFs for respiratory and cardiovascular disease were 0.12% (95% CI: 0.01-0.16%) and 0.10% (95% CI: 0.04-0.16%), respectively. The sum of the attributable burden of disease for four pollutants was about 297 person-years (PYs) (95% CI: 121-472 PYs) when the incinerators observed to the emission standards. The attributable burdens of respiratory disease and cardiovascular disease were about 0.2% and 0.1%, respectively, of the total burden of respiratory disease and cardiovascular disease of Seoul citizens for the year 2007. Although the air emissions from one risk factor, an incinerator, are small, the burden of disease can be significant to the public health when population exposure is considered.     

Estimation of greenhouse gas emissions from municipal wastewater treatment systems in India

Greenhouse gas (GHG) emissions generated from municipal wastewater treatment plants in India is estimated in this study. The emissions from the wastewater treatment process as well as from the electricity used during the treatment process are estimated by using the methodology of Intergovernmental Panel on Climate Change. The present treatment plants of capacity 15 997 million litres per day (MLD) contributes towards GHG emissions of 7.3 Mt of CO₂‐eq/year. The future GHG emissions would depend upon the treatment technology used for treating 34 109 MLD of untreated wastewater. The highest GHG emissions would occur if all new wastewater treatment plants are based on upflow anaerobic sludge blanket technology, 19.66 Mt CO₂‐eq/year and lowest if sequential batch reactor technology is adopted, 2.93 MtCO₂‐eq/year.     

A model for de novo synthesis and decomposition rates of dioxins and furans in municipal waste incinerators

We present a concise summary of a de novo synthesis model for the rates of formation of dioxins and furans in incinerators. Representative numerical results are used to illustrate numerical predictions and their utilization.     

气压和温度变化共同作用下垃圾填埋场边坡稳定性研究

城市生活垃圾填埋场在高渗沥液水位情况下发生边坡失稳滑坡的工程事故已多次发生,初步分析认为滑坡由渗沥液水位、垃圾降解产气和温度升高等因素共同引起。目前尚未见考虑渗沥液水位、气压和温度共同影响填埋场边坡稳定性研究的报道。通过简化垃圾填埋场气压和温度分布的计算,利用瑞典条分法进行考虑渗沥液水位、气压和温度共同影响的填埋场边坡稳定性分析。计算结果表明:考虑气压和温度的影响使得填埋场边坡稳定安全系数降低24.7%～43.0%;建议在同时考虑渗沥液水位、气压和温度的影响进行填埋场边坡稳定分析时,控制最小安全系数大于1.0可保证填埋场安全运行。本研究可为垃圾填埋场的设计、施工和运行管理提供理论支撑。     

Impact of medical waste incineration in the atmospheric PCDD/F levels of Porto, Portugal

As a consequence of a monitoring program of a new municipal waste incinerator initiated in 1998, a large data-base of dioxin and furan concentrations in the atmosphere of the metropolitan area of Porto, in northern Portugal, has been collected. The existence of this data coincides with the shutdown in January 2001 of two medical waste incinerators that were under operation in the inner city of Porto. Dioxin emissions from these facilities were measured indicating emissions 100 to 1000 times larger than recent European Union directive limits. Data show that the shutdown of these two units had a clear effect on the improvement of air quality in the region that was observed either on the overall level of dioxins and furans or as in subtle alterations of the homolog pattern of these compounds in the atmosphere.     

Increases in ambient PCDD/F and PCB concentrations in Northern Taiwan during an Asian dust storm episode

In spring 2006, an Asian dust storm (ADS) that originated in the deserts of Mongolia and China eventually reached populated areas of East Asia, including Taiwan. The concentrations of total suspended particles (TSP), vapor/solid-phase dioxin-like compounds and metal content in atmospheric aerosols were monitored at two sampling sites in northern Taiwan during the ADS episode: one along the northern coast (Site A), and the other in Taipei city (Site B). The ADS swept across northern Taiwan from 13 March to 19 March, 2006. Data indicate that the atmospheric dibenzo-p-dioxin and dibenzofuran (PCDD/F, 32.2 to 52.5 fg-I-TEQ/m(3)) and polychlorinated biphenyl (PCB, 2.23 to 4.49 fg-TEQ(WHO)/m(3)) concentrations measured at the two sampling sites prior to the ADS episode were considerably lower than those measured in other Asian countries. However, measurements made at both sites on 13 and 18 March 2006 indicate that the atmospheric PCDD/F and PCB concentrations increased 2.5 and 3.2 times at Site A, and 2.1 and 1.9 times at Site B, respectively, during the ADS episode. The concentrations of aluminum (Al), potassium (K) and Titanium (Ti) in atmospheric aerosols were also found to increase about 2 to 5 times during this period. As no specific dioxin emission sources exist within nearly 20 km of Site A, the increase in PCDD/F and PCB concentrations observed there is likely to be related to the ADS from mainland China. Additionally, the amount of PCDD/Fs bound to suspended particles increased from 257-259 to 339-512 pg-I-TEQ/g-TSP during the ADS episode. The distribution of OCDD congener observed in Taipei city increased dramatically during the ADS episode, however, the distribution of PCB congener did not vary significantly.     

Measurement of atmospheric PCDD/F and PCB distributions in the vicinity area of Waelz plant during different operating stages

A comprehensive sampling program was conducted at four sampling sites in the vicinity area of a Waelz plant prior to and after the retrofitting of this plant for reducing PCDD/F (polychlorinated dibenzo-p-dioxin and polychlorinated dibenzofuran) and polychlorinated biphenyl (PCB) emission to evaluate its effects on atmospheric PCDD/F and PCB concentrations. During the shutdown stage of the Waelz plant investigated, the atmospheric PCDD/F and PCB concentrations measured in the vicinity area (sites A, B and C) range from 24 to 170 fg-I-TEQ/m(3) and 5.0 to 8.2 fg-TEQ(WHO)/m(3), respectively. As the facility restarted to operate, the atmospheric PCDD/F and PCB concentrations measured increased to 570-1460 fg-I-TEQ/m(3) and 23-59 fg-TEQ(WHO)/m(3), respectively. When activated carbon injection (ACI) was adopted in the facility in early 2006, the PCDD/F concentrations measured in stack gas decreased dramatically from 190 to 3.4 ng-I-TEQ/Nm(3), while the PCB concentrations decreased from 4.9 to 0.08 ng-TEQ(WHO)/Nm(3). In the meantime, the atmospheric PCDD/F and PCB concentrations measured at sites A, B and C decreased to 150-340 fg-I-TEQ/m(3) and 13-19 fg-TEQ(WHO)/m(3), respectively. However, relatively high PCDD/F (180-1460 fg-I-TEQ/m(3)) and PCB (9.3-59 fg-TEQ(WHO)/m(3)) concentrations were measured at site D during all sampling stages. Overall, atmospheric sampling results indicate that over 50% of PCDD/Fs distributed in solid phase, while over 90% of PCBs distributed in vapor phase during all sampling stages.     

Ratio variation of congener profiles of PCDD/Fs and dioxin-like PCBs in human milk during lactation

This study investigates the compositional variations, changes in concentrations and contribution of particular congeners of PCDDs, PCDFs, non-ortho PCBs and mono-ortho PCBs in human milk from two mothers sampled during the 12-month lactation period. Total PCDD/F and dioxin-like PCB concentration in milk sampled from the primiparous mother on day 5 after delivery was 37 pg TEQ/g fat, and this value decreased significantly by 43% at 12 months. In milk sampled from the multiparous mother nursing her second child on day 5 after delivery was 12 pg TEQ/g fat, and this value decreased by 40% at 12 months. The decrease was statistically significant not for PCDD/Fs, but for dioxin-like PCBs. The ratio variance of the congener profiles of PCDD/Fs and dioxin-like PCBs in the milk remained similar during lactation. Moreover, the congener profiles of PCDD/Fs and dioxin-like PCBs in the milk showed similar percentages for both mothers independent of the lactation event and the number of previous births. The mean daily intake of dioxins by the infant nursed by the primiparous mother and the infant nursed by the multiparous mother up to six months of age was 140 and 46 pg TEQ/kg body weight, respectively. From seven to twelve months of age, the mean daily intake was 37 and 13 pg TEQ/kg body weight, respectively. Both values decreased by approximately 70%. The reasons why the mothers' body burden of dioxins decreased by breastfeeding and why the infants' daily intake of human milk per body weight decreased as the infant grows older consequently decreased were considered.     

Studies on the detection of salmonellae in municipal solid waste and incinerator residue

Significant factors in recovering Salmonella organisms from solid waste/sludge mixture, municipal solid waste, and incinerator residue and quench water were sample weight, number of samples, enrichment and subculture media, and incubation temperature. The optimal sample weight was 30 g; the optimal incubation temperature of inoculated enrichment medium, 39.5°C. The two enrichment media, Selenite F and Selenite brilliant green/sulfa, were equally efficient. The plating media were also important; best results were obtained with salmonella/shigella agar. Field studies conducted at four municipal incinerators of different operational design indicated that when enteric pathogens are present in the solid waste they can survive the incineration process.     

The influence of soluble organic matter from municipal solid waste compost on trace metal leaching in calcareous soils

The use of municipal solid waste (MSW) compost as fertilizer may cause increased leaching due to its high content of trace metals and thus pose a threat to groundwater quality. The effect of MSW compost application on trace metal leaching in calcareous soils has been studied in soil column experiments under laboratory conditions using three soils from the study area in the Gaza Strip and Israel. Higher levels of organic matter in solution (TOMS), nitrate, and the trace metals Cu, Ni and Zn were found in the leachates of a sandy soil and, to a lesser extent, a loamy soil, to which MSW compost had been applied at a rate of 65 Mg ha(-1) (dry weight basis). Nevertheless, the majority of water-soluble trace metal species from compost accumulated in the topsoil rather than washing out, with the exception of aqueous Ni species. Ni concentrations exceeded the maximum allowable limits for drinking water (in Germany: 50 microg l(-1)) at peak times in the leachates from sandy soil, while all other trace metals remained far below the corresponding limits. The highest absolute concentrations of trace metals were found for the leaching of Cu from compost-amended sandy soil (100 microg l(-1)). For Cd, Pb and Hg no evidence of downward movement was found in any assay. Gel filtration studies of the collected soil leachates showed that all trace metals encountered in the leachates existed mostly as organic complexes. In sandy soil most of the water-soluble organic matter added with the compost had leached from the rootzone after a year's equivalent of rainfall, while TOMS mobility was greatly reduced in the loamy soil. The makeup of the TOMS in the sandy soil and its metal-binding capacity was strongly influenced by compost-derived dissolved organic matter (DOM) as observed by FTIR spectrometry. Hence the vertical displacement of trace metals (Cu, Ni, Zn) in these calcareous soils seemed to result primarily from the presence of mobile metal-organic complexes in the soil solution after compost addition. Further studies are required to validate these findings in the field, especially to assess the risk of Cu and Ni leaching in sandy soil.     

Suspended particulate variations and mass size distributions of incense burning at Tzu Yun Yen temple in Taiwan,Taichung

Concentrations of eight trace elements (As, Cd, Cu, Hg, Ni, Pb, Se and Zn), lindane and six groups of organic contaminants (total-chlordane, total-PCB, total-DDT, Dieldrin and Aldrin, total-butyltins, total-PAHs) at the 11 NOAA mussel watch project (MWP) sites located in North and South Carolina have been compared with the national US MWP data. Three sites from North and South Carolina had concentrations of PAHs in the upper 15th percentile on a national scale. One site had high concentrations of butyltins, and two sites had high Se concentrations. All sites from Beaufort, North Carolina, south had high As concentrations. Decreasing temporal trends were found for As, Cd, total-chlordane, DDT, PCB, and PAHs at some sites.     

气体压力和孔隙对垃圾土体气体渗透系数影响的研究

垃圾土的非饱和气体渗透系数是填埋场气体运移分析和抽气井设计的重要参数,孔隙比、有机物含量、饱和度等是影响垃圾土渗透特性的主要因素。通过研制的垃圾土非饱和渗透试验仪,进行了不同影响因素下的非饱和垃圾土气体渗透试验,发现渗透系数随渗透压力呈现非线性特性,可以用Forchheimer非达西渗流方程较好地拟合。孔隙比增加,渗透系数增大,非达西系数Ba逐渐减小,分界点的气体压力减小;有机物含量越高,渗透系数越小,分界点气体压力越大;片状分布有机物使有效连通的渗透路径减少是垃圾体气体渗透特性降低的原因;饱和度越高,垃圾土的渗透系数越小,分界点气体压力越大;在试验的有效孔隙范围内,渗透系数、分界点气体压力与有效孔隙呈现较好的相关关系、非达西系数变化不大。     

Utilization of municipal solid waste incineration ash in stone mastic asphalt mixture: Pavement performance and environmental impact

The objective of this study is to the use of municipal solid waste incinerator (MSWI) fly ash as a partial replacement of fine aggregate or mineral filler in stone matrix asphalt (SMA) mixture. For saving natural rock and reusing solid waste, basic oxygen furnace slag (BOF slag) was used as part of coarse aggregate. And this makes SMA mixtures contain more than 90% solid waste materials by mass. A comparative study of the performance of two mixes designed using superior performance asphalt pavements (SUPERPAVE) and Marshall mix design procedures was carried out in this research. Samples from both mixes were prepared at the design asphalt contents and aggregate gradations and were subjected to a comprehensive mechanical evaluation testing. These tests included Marshall stability, water sensibility, resilient modulus, fatigue life and rutting. In all the performed tests SUPERPAVE mixtures proved their superiority over Marshall mixtures. TCLP test for environmental impact indicated that asphalt is an effective stabilization and solidification agent for heavy metal in MSWI ash. The heavy metal leachates in TCLP tests have great positive correlation with their initial concentration in waste. But Ni is an exception that lower initial concentration leaded to higher cumulative leaching rate.     

Spatial distribution and temporal variation of metals in the vicinity of a municipal solid waste incinerator after a modernization of the flue gas cleaning systems of the facility

In June 1994 and 1997, the concentrations of a number of elements were determined in soil and herbage samples collected in the vicinity of a municipal solid waste incinerator (MSWI) (Tarragona, Catalonia, Spain). In August 1997, an adaptation to the EU legislation on pollutant emissions from the stack was carried out to the incinerator. In June 1999, soil and herbage samples were collected again at the same sampling points and the levels of arsenic (As), cadmium (Cd), chromium (Cr), lead (Pb), manganese (Mn), mercury (Hg), nickel (Ni) and vanadium (V) were measured by ICP-MS or AAS with graphite furnace. The results are compared with those obtained in the 1994 and 1997 surveys. In the period 1997-1999, the only significant changes in soil levels corresponded to Cd and Pb, with decreases of 21.0% and 53.5%, respectively. In vegetation, only Mn levels showed a significant reduction, which contrasts with the notable increases found in the concentrations of As, Hg and Ni. According to the results of this survey, it seems evident that other metal emission sources in the same area of study are masking the environmental improvements carried out in the MSWI.     

Comparing the anaerobic digestion of Ascophyllum nodosum,the organic fraction of municipal solid waste and white rice in batch reactors

The biogas potential of marine macroalga Ascophyllum nodosum was compared with the organic fraction of municipal solid waste (OFMSW) and white rice to determine the applicability of the feedstock for anaerobic digestion. For OFMSW three dry matter contents were compared, 3%, 10% and 25%, to determine the effect of dry matter on methane yield. Biogas was evolved in each system, but the rate of evolution of biogas changed with moisture content. The highest total methane yield was obtained from 3% OFMSW but A. nodosum yielded more methane at 176±37.62 L/kg VS than white rice and the drier anaerobic digestion of OFMSW. The substrates were digested using wastewater treatment plant inoculum to determine gas yield and gas quality under batch mesophilic digestion conditions.