Municipal solid waste landfill age and refuse-derived fuel.

Landfill sites are hard to obtain in Taiwan. Municipal solid waste (MSW) in the closed landfill sites has high combustible content and calorific value (CV). Therefore, activating the closed landfill sites as municipal mine sites to prolong their service life will promote a sustainable environment. This study transforms combustibles from the closed municipal landfill sites of different landfill ages (LAs) into refuse-derived fuel (RDF) through pretreatment and squeeze forming equipment, so to investigate the characteristics of the MSW of different LAs, and the manufacturing conditions and firing behaviour of RDF. The results indicate that the proportion of the combustibles in MSW declines as the LA grows, and therefore the proportions of both incombustible materials and soil and debris correspondingly increased. The LA of the MSW is thus negatively correlated with the CV. The MSW at the LA of 10 years still has high potential as fuel material. The fixed carbon initiation temperatures (i.e. ignition temperatures) of combustibles of the MSW at the LAs of 1 year, 5 years and 10 years are 259°C, 256°C and 245°C, respectively. The CV and flame temperature of the RDF increase slightly with the increasing squeeze temperature (ST) at 100-120°C, but it will decrease when the ST reaches 130°C. Therefore, this study recommends the squeeze pressure of the RDF as 41.65 ± 8.24 kg cm-2, ST 110°C and combustible size 10-20 mm.

Destruction kinetic of PCDDs/Fs in MSWI fly ash using microwave peroxide oxidation.

Microwave peroxide oxidation is a less greenhouse gas emission and energy-efficient technology to destroy toxic organic compounds in hazardous waste. The research novelty is to adopt the innovative microwave peroxide oxidation in H2SO4/HNO3 solution to efficiently destroy the polychlorinated dibenzo-p-dioxins (PCDDs)/Fs in municipal solid waste incineration fly ash. The major objective of this paper is to study dynamic destruction of PCDDs/Fs using the microwave peroxide oxidation. Almost all PCDDs/Fs in the raw fly ash can be destructed in 120 min at a temperature of 423 K using the microwave peroxide oxidation treatment. It was found that the microwave peroxide oxidation provides the potential to destruct the PCDDs/Fs content in municipal solid waste incinerator (MSWI) fly ash to a low level as a function of treatment time. A useful kinetic correlation between destruction efficiency and treatment conditions is proposed on the basis of the experimental data obtained in this study. The significance of this work in terms of practical engineering applications is that the necessary minimum treatment time can be solved using a proposed graphic illustration method, by which the minimum treatment time is obtained if the desired destruction efficiency and treatment temperature are known. Because of inorganic salt dissolution, the temperature would be a critical factor facilitating the parts of fly ash dissolution. Material loss problem caused by the microwave peroxide oxidation and the effects of treatment time and temperature are also discussed in this paper.

Development of a methodology for strategic environmental assessment: application to the assessment of golf course installation policy in Taiwan.

Some countries, including Taiwan, have adopted strategic environmental assessment (SEA) to assess and modify proposed policies, plans, and programs (PPPs) in the planning phase for pursuing sustainable development. However, there were only some sketchy steps focusing on policy assessment in the system of Taiwan. This study aims to develop a methodology for SEA in Taiwan to enhance the effectiveness associated with PPPs. The proposed methodology comprises an SEA procedure involving PPP management and assessment in various phases, a sustainable assessment framework, and an SEA management system. The SEA procedure is devised based on the theoretical considerations by systems thinking and the regulative requirements in Taiwan. The positive and negative impacts on ecology, society, and economy are simultaneously considered in the planning (including policy generation and evaluation), implementation, and control phases of the procedure. This study used the analytic hierarchy process, Delphi technique, and systems analysis to develop a sustainable assessment framework. An SEA management system was built based on geographic information system software to process spatial, attribute, and satellite image data during the assessment procedure. The proposed methodology was applied in the SEA of golf course installation policy in 2001 as a case study, which was the first SEA in Taiwan. Most of the 82 existing golf courses in 2001 were installed on slope lands and caused a serious ecological impact. Assessment results indicated that 15 future golf courses installed on marginal lands (including buffer zones, remedied lands, and wastelands) were acceptable because the comprehensive environmental (ecological, social, and economic) assessment value was better based on environmental characteristics and management regulations of Taiwan. The SEA procedure in the planning phase for this policy was completed but the implementation phase of this policy was not begun because the related legislation procedure could not be arranged due to a few senators' resistance. A self-review of the control phase was carried out in 2006 using this methodology. Installation permits for 12 courses on slope lands were terminated after 2001 and then 27 future courses could be installed on marginal lands. The assessment value of this policy using the data on ecological, social, and economic conditions from 2006 was higher than that using the data from 2001. The analytical results illustrate that the proposed methodology can be used to effectively and efficiently assist the related authorities for SEA.

Distribution of chloride ion in MSWI bottom ash and de-chlorination performance.

When recycling bottom ash from municipal solid waste incinerators (MSWIs), salts and heavy metals contents must be considered; in particular, chloride ions must be addressed because they cause serious corrosion in metals. Therefore, only limited amounts of bottom ash can be utilized as a substitution for material or the bottom ash must be treated at high temperatures prior to use. These factors markedly decrease the applications of bottom ash. In addition to the distribution characteristics of chloride ions, this study also investigates the characteristics change before and after de-chlorination using a counter-flow pipe column and three different flow fluxes for different refuse incinerators as the experiment variables. Thus, this study attempts to determine the appropriate conditions for de-chlorination and an appropriate policy for use of bottom ash as concrete aggregate. The experimental results show that a negative correlation exists between the natural logarithm of the chloride ion concentration and particle size in bottom ash. Characteristics of de-chlorinated bottom ash, such as pH value, mud content, loss on ignition, chloride ion concentration, turbidity, and species intensity, all decrease, meaning that de-chlorination decreased chloride ion content and generates a cleaning effect. The per-unit-time efficiency of de-chlorination is highest in the high flux flow. When flow flux is 80 mL/min, the de-chlorination efficiency is >0.3%/h. However, the shortest time required for bottom ash de-chlorination does not reduce in proportion to the legally prescribed concentration of chloride ion.

Development of a multiple objective planning theory and system for sustainable air quality monitoring networks.

Air quality monitoring data are important bases for air quality management strategies planning and performance assessment. Therefore, the environmental protection authorities need to plan the air quality monitoring network effectively. However, in Taiwan, the national Environmental Protection Administration (EPA) and some county environmental protection bureaus (EPB) separately installed their own monitoring stations. This study developed an integrated methodology and computer system for planning air quality monitoring networks. The environmental, social, and economic objectives and sub-objectives, and their weights were identified using system analysis and multiple objective planning, based on the principles of sustainable development. A multiple objective optimization model and procedure for sustainable air quality monitoring networks planning are developed in this study. According to the procedure, a multiple objective planning system for sustainable air quality monitoring networks (MOPSSAQMN) is developed using computer software based on the modified bounded implicit enumeration algorithm with the constraint arrangement method. The air quality monitoring network of Taoyuan County, in northern Taiwan, was used as a case study to demonstrate the proposed method. Two satisfactory alternatives based on different conditions were generated using MOPSSAQMN. The compared results show that this study generated better alternatives than the current monitoring network. An installation schedule for the alternative was proposed, and its first step is now being implemented by the EPB of Taoyuan County Government. The procedure and computer system developed in this study can be used to assist the competent authorities to devise good and different alternatives for air quality monitoring networks planning.

Lightweight aggregate made from sewage sludge and incinerated ash.

In this study, sewage sludge ash (SSA), with similar characteristics to expansive clay, was used as the principal material and sewage sludge (SS) as the admixture to sinter lightweight aggregate and to study the influences of raw material composition on pelletising, sintering effect and aggregate properties. Results showed that both SS and SSA could be sintered to produce synthetic aggregates individually or mixed. Increasing the amount of SS would decrease the pelletising ratio. Under the consideration of energy saving, the mixture of SSA was better for sintering normal weight aggregate. On the contrary, the mixture that added 20-30% of SS was more adequate to make lightweight aggregates. Adding SS would enhance the oxidation-reduction reaction and lower the bulk density and sintering temperature of aggregates to save energy. Sintering temperature affected the properties of sewage sludge ash lightweight aggregate (SSALA) more than retention period did. Prolonging the retention period could improve bloating effect.

Development of a dynamic strategy planning theory and system for sustainable river basin land use management.

Land use management is central to government planning for sustainable development. The main purpose of this study is to develop a novel strategy planning theory and system to assist responsible authorities in obtaining alternatives of sustainable top river basin land use management. The concepts and theory of system analysis, driving force-state-response (DSR) framework, and system dynamics are used to establish the DSR dynamic strategy planning procedure in this work. The integrated management of the land, water, and air resources of a river basin system is considered in the procedure. Two modified land use management procedures combined with the DSR dynamic strategy planning procedure are developed in this work. Based on the DSR dynamic strategy planning procedure, the sustainable river basin land use management DSR dynamic decision support system (SRBLUM-DSRD-DSS) is developed by using the Vensim, MS Excel, ArcView, and Visual Basic software. The concepts of object-orientation are used to develop the system dynamic optimization and simulation models of SRBLUM-DSRD-DSS. Based on the modified land use management procedures, SRBLUM-DSRD-DSS is used to assist decision makers in generating the land use plans of the Nankan river basin in Taoyuan County of Taiwan. Since the decisions of land, water and air resources management are still made at different agencies, the land use management system should be modified based on the innovational procedure to implement the management strategy developed in this work. The results show that the modified land use management procedures can be a guidance for the governments in modifying the systems and regulation of urban and regional plans in Taiwan.

Transparent conductive oxide films embedded with plasmonic nanostructure for light-emitting diode applications.

In this study, a spin coating process in which the grating structure comprises an Ag nanoparticle layer coated on a p-GaN top layer of InGaN/GaN light-emitting diode (LED) was developed. Various sizes of plasmonic nanoparticles embedded in a transparent conductive layer were clearly observed after the deposition of indium tin oxide (ITO). The plasmonic nanostructure enhanced the light extraction efficiency of blue LED. Output power was 1.8 times the magnitude of that of conventional LEDs operating at 350 mA, but retained nearly the same current-voltage characteristic. Unlike in previous research on surface-plasmon-enhanced LEDs, the metallic nanoparticles were consistently deposited over the surface area. However, according to microstructural observation, ITO layer mixed with Ag-based nanoparticles was distributed at a distance of approximately 150 nm from the interface of ITO/p-GaN. Device performance can be improved substantially by using the three-dimensional distribution of Ag-based nanoparticles in the transparent conductive layer, which scatters the propagating light randomly and is coupled between the localized surface plasmon and incident light internally trapped in the LED structure through total internal reflection.

Characteristics of PCDD/F content in fly ash discharged from municipal solid waste incinerators.

Different from most previous studies with quantity-limited data, this paper presents PCDD/F content characterization in the fly ash discharged from sixteen large-scale commercial MSWIs. From the results with over hundreds of data using periodically sampling and analysis, it was found that the PCDD/F contents in the fly ash were from 9.07 to 46.68ng/g, d.w., and if based on international toxicity equivalent quantity, they were from 0.78 to 2.86ng I-TEQ/g, d.w. The higher chlorinated PCDDs likely dominated more than lower chlorinated PCDDs, but this tendency was not for PCDFs. The OCDD had the highest contribution to the total PCDD/F content, but if based on I-TEQ content, 2,3,4,7,8-PeCDF is the PCDD/F congener with the highest toxicity contribution. Moreover, the PCDD/F characteristic index (DCI) is suggested using the representative congener content of 2,3,4,7,8-PeCDF to characterize the fly ash. The DCI is 0.875±7.6% for the fly ash discharged from the MSWI with the APCD assembly of SD, AC and BF. The findings obtained in this work provide overview information on the PCDD/F content characterization in fly ash. They will provide PCDD/F fingerprint information to distinguish from other PCDD/F sources, like steel refinery industry, hazardous waste incinerators, or cement kilns, and thus be applied to fly ash management in the environment.

Sustainable water quality management framework and a strategy planning system for a river basin.

In Taiwan, the authorities have spent years working on remedying polluted rivers. Generally, the remediation planning works are divided into two phases. During the first phase, the allowed pollution discharge quantity and abatement quantity of each drainage zone, including the assimilative capacity, are generated based on the total river basin. In the second phase, the abatement action plans for each pollution source in each drainage zone are respectively devised by the related organizations based on the strategies generated during the first phase. However, the effectiveness of linking the two phases is usually poor. Highly integrated performances are not always achieved because the separate two-phase method does not take system and management thinking into consideration in the planning stage. This study pioneers the use of the Managing for Results (MFR) method in planning strategies and action plans for river water quality management. A sustainable management framework is proposed based on the concept and method of MFR, Management Thinking, and System Analysis. The framework, consisting of planning, implementation, and controlling stages, systematically considers the relationships and interactions among four factors: environment, society, economy, and institution, based on the principles of sustainable development. Based on the framework, the Modified Bounded Implicit Enumeration algorithm, which is used as a solving method, is combined with Visual Basic software and MS Excel to develop a computer system for strategy planning. The Shetzu River, located in northern Taiwan, is applied as a case study. According to the theoretical, practical, and regulatory considerations, the result-oriented objectives are defined to first improve the pollution length of the Shetzu River in specific remediation periods to finally meet regulated water quality standards. The objectives are then addressed as some of the constraints for the strategy planning model. The model objective is to pursue the maximum assimilative capacity (environmental phase) subjected to the constraints of water quality standards (institutional phase), social equity (social phase), and proper available technology (economic phase). The pollution quantity abatement and allocation, which are named the top strategies, of each drainage zone for different scenarios can be obtained based on each water quality standard. The middle as well as lower strategies and action plans, which consist of pollution quantity abatement and allocation of each class (domestic, industrial, livestock, and non-point pollution sources) and their individual pollution sources in each drainage zone, are then generated based on the top strategies. The performance indicators and measure plans are proposed based on the action plans to promote the comprehensive effectiveness of river water quality management. The authorities have begun to develop a budget based on the strategies and action plans developed in this study. The analytical results indicate that the objectives, strategies, and action plans developed based on the sustainable management framework and strategy planning system can effectively help the related authorities to fulfill the tasks of water quality management for a river basin.