Effects of chlorides on emissions of toxic compounds in waste incineration: study on partitioning characteristics of heavy metal

Chlorides derived from plastics and food residue content in MSW will affect the formation and partitioning of metal chlorides in the incineration discharges. Our study investigated the effects of waste-derived chlorides on the partitioning of heavy metals in a single-metal combustion system. The results indicate that the heavy metal partitioning behaviors are mainly affected by the presence of chloride, alkaline metals (i.e., Na, K) and moisture in the wastes. The configuration of the metal partitioning is determined by the availability of chlorine, hydrogen, and alkaline metals, or the extent to which the elements may divide from their compounds at a given combustion temperature. The effects of chlorides, including PVC, C2Cl4, FeCl3, NaCl and KCl, were also discussed.     

Effect of SiO2 on immobilization of metals and encapsulation of a glass network in slag

The final disposal of ash from an incinerator is of special concern because of the possibility of its releasing toxic substances. Melting/vitrification has been regarded as a prospective technology of ash treatment. The object of this investigation was to evaluate the effect of silica (SiO2) addition on the immobilization of hazardous metals and the encapsulation of a glass network during the vitrification process. Four specimens with SiO2/fly ash mixing ratios of 0, 0.1, 0.2, and 0.3, respectively, were tested. The mobility of metals in slag was then estimated by a sequential extraction procedure. X-ray diffraction analysis indicates that SiO2 leads to the polymerization of silicates. The encapsulation of aluminum, calcium, and magnesium would not be observed unless adequate amount of SiO2 was added. It was also found that SiO2 addition enhances the formation of a compact and interconnected glass network structure and, thus, contributes to the chemical stability of metals in slag. After vitrification, the mobility of cadmium, copper, iron, chromium, nickel, lead, and zinc was significantly reduced. However, there is no significant correlation between the immobilization of these metals and the addition of SiO2.     

Control of particle re-entrainment by wetting the exposed surface of dust samples

Experiments have been conducted in a wind tunnel to measure the emission factor of re-entrained particles from a dry or wetted dust sample with a smooth or rough surface. Effects of wind velocities and water contents in the sample on the emission factor also were investigated. The results show that re-entrainment of particles can be controlled efficiently in a certain period of time when the surface watering density is between 60 and 80 g/m2 at a wind velocity from 7 to 15 m/sec for both smooth and rough surfaces. After the effective period is elapsed, which depends on wind speeds and environmental conditions, water will eventually evaporate, and re-entrainment starts to occur again. The experimental water evaporation rates at different wind speeds are in good agreement with theoretical values. After watering for 210, 130, and 110 min at average wind velocities of 0, 2, and 4 m/sec, respectively, the dust sample must be replenished with water to avoid dust re-entrainment.     

Emissions of polychlorinated dibenzo-p-dioxins and dibenzofurans from stack flue gases of sinter plants

This study investigated four sinter plants, classified into two categories--with selective catalytic reduction (SCR) (S1, S2 and S3) and without SCR (S4) as its air pollution control device. Polychlorinated dibenzofurans (PCDFs) are dominant in the stack flue gases of sinter plants with and without SCR. The polychlorinated dibenzofurans/polychlorinated dibenzo-p-dioxins (PCDFs/PCDDs) ratio exceeds 1 extremely. The degree of chlorination of the sinter plant without SCR is towards hepta and hexa congeners while that of the sinter plant with SCR is towards penta and hexa congeners. PCDD/Fs are indeed decomposed (75.5% and 69% on ng and ng TEQ bases, respectively) and not only reduced in degree of chlorination. The overall concentration in the stack flue gas of sinter plants with SCR (7.97-14.1 ng/Nm(3); 0.995-2.06 ng TEQ/Nm(3)) is lower than that of the sinter plant without SCR (28.9 ng/Nm(3); 3.10 ng TEQ/Nm(3)). In Taiwan, based on the emission factors of 0.970 microg TEQ/ton-feedstock (sinter plants with SCR) and 3.13 microg TEQ/ton-feedstock (sinter plant without SCR), the annual PCDD/F emission of 44.7 g TEQ/year from sinter plants is 60 and 121 times higher than those from municipal solid waste incinerators (0.750 g TEQ/year) and MWIs (0.369 g TEQ/year). These results show that sinter plants have become the dominating PCDD/F emission source since tighter emission limits have been applied to incinerators.     

The Integration of a Genetic Programming-Based Feature Optimizer With Fisher Criterion and Pattern Recognition Techniques to Non-Intrusive Load Monitoring for Load Identification

Identification of electricity energy consumption on individual household appliances used in a smart house is the first important step for making the use and conservation of electricity energy more efficient. In the past, Non-Intrusive Load Monitoring (NILM) techniques, which are part of smart grid techniques realized to improve electricity energy usage efficiency, have been developed to identify individual appliances with avoiding installing many smart meters for appliances in a field. In this paper, a new NILM technique that integrates an efficient Genetic Programming (GP)-based feature optimizer with pattern recognition techniques is proposed to identify which appliance is being turned on or off. The proposed GP-based feature optimizer with Fisher criterion is used to generate a more efficient feature than original potential transient features extracted from captured transient response of household appliances through analysis of NILM. The new feature generated by GP is used by pattern recognition techniques as load identifiers for load identification. The load identifiers used and compared in this paper include k-Nearest-Neighbor Rule, Back-Propagation Artificial Neural Network, and Learning Vector Quantization. Experiments are conducted under different single-load and multiple-load operation circumstances at different actual experimental environments with small disturbances. As shown from the experimental results, the proposed is confirmed to be feasible and usable.     

Cross‐cultural comparisons between the earthquake preparedness models of Taiwan and New Zealand

Taiwan and New Zealand are both located in the Pacific Rim where 81 per cent of the world's largest earthquakes occur. Effective programmes for increasing people's preparedness for these hazards are essential. This paper tests the applicability of the community engagement theory of hazard preparedness in two distinct cultural contexts. Structural equation modelling analysis provides support for this theory. The paper suggests that the close fit between theory and data that is achieved by excluding trust supports the theoretical prediction that familiarity with a hazard negates the need to trust external sources. The results demonstrate that the hazard preparedness theory is applicable to communities that have previously experienced earthquakes and are therefore familiar with the associated hazards and the need for earthquake preparedness. The paper also argues that cross‐cultural comparisons provide opportunities for collaborative research and learning as well as access to a wider range of potential earthquake risk management strategies.     

PM<Subscript>2.5</Subscript> particulates and metallic elements (Ni,Cu, Zn,Cd and Pb) study in a mixed area of summer season in Shalu,Taiwan

PM_2.5 has become an important environmental issue in Taiwan during the past few years. Moreover, electricity increased significantly during the summertime and TTPP generated by coal burning base is the main electricity provider in central Taiwan. Therefore, summer season has become the main research target in this study. The ambient air concentrations of particulate matter PM_2.5 and PM₁₀ collected by using VAPS at a mixed characteristic sampling site were studied in central Taiwan. The results indicated that the average daytime PM_2.5 and PM₁₀ particulate concentrations were occurred in May and they were 44.75 and 57.77 µg/m³ in this study. The results also indicated that the average nighttime PM_2.5 and PM₁₀ particulate concentrations were occurred in June and they were 38.19 and 45.79 µg/m³ in this study. The average PM_2.5/PM₁₀ ratios were 0.7 for daytime, nighttime and 24-h sampling periods in the summer for this study. This value was ranked as the lowest ratios when compared to the other seasons in previous study. Noteworthy, the results further indicated that the metallic element Pb has the mean highest concentrations for 24-h, daytime and nighttime sampling periods when compared to those of the other metallic elements (Ni, Cu, Zn and Cd). The average mean highest metallic Pb concentrations in PM10 were 110.7, 203.0 and 207.2 ng/m³ for 24-h, daytime and nighttime sampling periods in this study. And there were 59.53, 105.2 and 106.6 ng/m³ for Pb in PM2.5 for 24-h, daytime and nighttime sampling periods, respectively. Moreover, the results further indicated that mean metallic element Pb concentrations on PM_2.5 and PM₁₀ were all higher than those of the other elements for 24 h, day and nighttime.     

The effects assessment of firm environmental strategy and customer environmental conscious on green product development

The purpose of this study is to examine why both parties (industry and consumer market) have mutual interests in protecting the environment but they still are hesitant to act green. The study used two-stage sampling from consumer market to depict ideal green product characteristics and reliable toy companies, and visit these companies for the second sample collection to examine whether the organizational eco-innovation strategy with customer value has a positive effect on green product development. In other words, the customer's benefit is an important factor for new product development strategy for green toys. This research shows that the willingness to buy green toys increases if most people in society buy green toys. This represents that customers are environmentally conscious and care about protecting the environment, or buying green toys is the result of a new economic trend and childhood education. The willingness to buy green toys increases if customers think that green products implies an enhancement on new product development to toy manufacturers. Further, if manufacturers are able to manage the difficulty of cooperation with all parties in the supply chain and difficulties related to production, they are willing to adopt customers' perceived value on green toys for their new product development strategy. It is rare to find academic research discussing the perspectives of both consumers and manufacturers in the same study because the research topic is very broad and many conditions must be considered. This research aims to find the effect of consumer-perceived value and company eco-innovation on green product development.     

A model for the implementation of a two-shift municipal solid waste and recyclable material collection plan that offers greater convenience to residents

Separating recyclables from municipal solid waste (MSW) before collection reduces not only the quantity of MSW that needs to be treated but also the depletion of resources. However, the participation of residents is essential for a successful recycling program, and the level of participation usually depends on the degree of convenience associated with accessing recycling collection points. The residential accessing convenience (RAC) of a collection plan is determined by the proximity of its collection points to all residents and its temporal flexibility in response to resident requirements. The degree of proximity to all residents is determined by using a coverage radius that represents the maximum distance residents need to travel to access a recycling point. The temporal flexibility is assessed by the availability of proximal recycling points at times suitable to the lifestyles of all residents concerned. In Taiwan, the MSW collection is implemented at fixed locations and at fixed times. Residents must deposit their garbage directly into the collection vehicle. To facilitate the assignment of collection vehicles and to encourage residents to thoroughly separate their recyclables, in Taiwan MSW and recyclable materials are usually collected at the same time by different vehicles. A heuristic procedure including an integer programming (IP) model and ant colony optimization (ACO) is explored in this study to determine an efficient two-shift collection plan that takes into account RAC factors. The IP model has been developed to determine convenient collection points in each shift on the basis of proximity, and then the ACO algorithm is applied to determine the most effective routing plan of each shift. With the use of a case study involving a city in Taiwan, this study has demonstrated that collection plans generated using the above procedure are superior to current collection plans on the basis of proximity and total collection distance.     

Environmental hazards and health risk of common liquid perfluoro-n-alkanes, potent greenhouse gases

This article aimed at introducing the main physical properties and commercial/industrial uses of common liquid perfluoro-n-alkanes (including perfluoropentane, perfluorohexane, perfluoroheptane, perfluorooctane, and perfluorononane) and the environment and health hazards posed by their toxic decomposition products (especially in hydrogen fluoride and perfluoroisobutylene) because these perfluorocompounds are potent greenhouse gases, which have been blanketed into the Kyoto Protocol, but was rarely described in the National Inventory Reports by Annex I Parties. The environmental properties (including octanol-water partition coefficient, water solubility and Henry's law constant) of liquid perfluoro-n-alkanes were evaluated, and further discussed were its atmospheric implications according to the predicted properties and possible proposal for the formation of trifluoroacetic acid (CF(3)COOH) in the atmosphere by the ionized photolysis. These predicted values revealed that liquid perfluoro-n-alkanes tend to be hydrophobic and partitioned into organic matter, and they have exceptionally low solubility in water and extremely high vaporization from the water bodies, suggesting that it will sink into the atmosphere if it is released into the environment.