Applicability assessment of empty fruit bunches from palm oil mills for use as bio-solid refuse fuels.

Palm kernel shells (PKS), empty fruit bunches (EFB), and trunks are by-products of the palm oil industry and form approximately 50 wt % of fresh fruit bunch (FFB). In particular, EFB accounts for approximately 20 wt % of FFB. Although large amounts of EFB are generated from palm oil mills every year in Indonesia and Malaysia, EFB is treated as waste because commercial technologies for thermo-chemical conversion of EFB into renewable energy are still under development. A robust conversion method can transform EFB into an appealing renewable energy source. In order to secure this renewable energy source, Korea can import EFB as biomass. This paper investigates literature on the status of utilization of EFB, by-products from palm oil mills in order to identify the best available technological process to use EFB as bio-solid refuse fuels (SRF). Meanwhile, physico-chemical analyses (proximate, elemental, and calorific value analyses), biomass and heavy metal content were measured in order to assess whether EFB would be suitable for use as a bio-SRF, in accordance with the Korean quality standard for SRF. According to the analysis results, EFB showed applicability to use as bio-SRF; main analysis results - moisture (9.63 wt %), ash (5.94 wt %), biomass content (97.82 wt %) and calorific value (3668 kcal kg).

Strategic environmental assessment for effective waste management in Korea: A review of the new policy framework.

This study examines the new policy framework, which includes effective environmental assessment procedure to manage waste in Korea. Concept of this framework pursues the important strategies toward the waste reduction, preservation of landfill area, stabilization and removal of hazardous substance in wastes, and optimal treatment for energy and material recovery from wastes. Therefore, it has begun on three points. First, activating the effective recycling system to reuse wastes will be essential to waste reduction. Second, the utilization of substitute resource can be expected through the optimal transforming the wastes into the recycled product, raw material, thermal energy, etc. Third, the characteristics of waste must be evaluated by strategic environmental assessment. To realize this concept, the strategic environment assessment with reinforcement of hazardous property, categorization of recycling type, and classification of environmental assessment procedure depending on the recycling type was provided. In addition, based on this environment assessment, the new policy framework was built through the established and revised Wastes Control Act by focusing on simple systematic procedure for decision of the possible recycling and strengthening the safety of the wastes to a higher level with promoting recycling activities.

Aspect ratio has no effect on genotoxicity of multi-wall carbon nanotubes.

Carbon nanotubes (CNTs) have specific physico-chemical and electrical properties that are useful for telecommunications, medicine, materials, manufacturing processes and the environmental and energy sectors. Yet, despite their many advantages, it is also important to determine whether CNTs may represent a hazard to the environment and human health. Like asbestos, the aspect ratio (length:diameter) and metal components of CNTs are known to have an effect on the toxicity of carbon nanotubes. Thus, to evaluate the toxic potential of CNTs in relation to their aspect ratio and metal contamination, in vivo and in vitro genotoxicity tests were conducted using high-aspect-ratio (diameter: 10-15 nm, length: ~10 µm) and low-aspect-ratio multi-wall carbon nanotubes (MWCNTs, diameter: 10-15 nm, length: ~150 nm) according to OECD test guidelines 471 (bacterial reverse mutation test), 473 (in vitro chromosome aberration test), and 474 (in vivo micronuclei test) with a good laboratory practice system. To determine the treatment concentration for all the tests, a solubility and dispersive test was performed, and a 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) solution found to be more suitable than distilled water. Neither the high- nor the low-aspect-ratio MWCNTs induced any genotoxicity in a bacterial reverse mutation test (~1,000 µg/plate), in vitro chromosome aberration test (without S9: ~6.25 µg/ml, with S9: ~50 µg/ml), or in vivo micronuclei test (~50 mg/kg). However, the high-aspect-ratio MWCNTs were found to be more toxic than the low-aspect-ratio MWCNTs. Thus, while high-aspect-ratio MWCNTs do not induce direct genotoxicity or metabolic activation-mediated genotoxicity, genotoxicity could still be induced indirectly through oxidative stress or inflammation.

Practices in dioxin emission reduction by special regulatory enforcement and utilizing advanced control technologies for incinerators in Korea.

This study strives to estimate the emission of dioxin and furthermore attempts to find the best technological control methods available for waste incinerators by investigating the emission status thereof. In order to incorporate the Stockholm Convention, a particular stringent law was promulgated in Korea and in recent years incinerators were forced to utilize better technological control. After the enforcement of special dioxin emission regulation in 2003, the average concentration of dioxin emitted from municipal and industrial waste incinerators decreased from 15.25 and 12.86 ng TEQ Nm(-3) to 5.53 and 4.96 ng TEQ Nm(-3) in 2001 and 2004, respectively. Based on test results at commercial plants, several best arranged sets of air pollution control devices (APCDs) were suggested in order to provide guidelines to help operators. These sets included combinations of spray dry absorbers, bag type filters, wet scrubbers, selective catalytic reductions and electrostatic precipitators. Different suggestions and real installations of APCD arrangement were investigated during the years around the regulation in effective. The results were presented depending on the capacity of the incinerators and different waste streams to observe the efforts to reduce dioxin emission by operators of incineration plants. The annual amount of dioxin emission from the incinerators is expected to be 212.5 g-TEQ in 2011 and 234.3g-TEQ in 2015, respectively, compared to 891.6g-TEQ recorded in 2001. The enforcement of new regulation and the installation of better APCDs showed the significant effect on such reduction. This reduction in dioxin emission from incinerators confirmed the nation's commitment to the regulatory requirement set by the Stockholm Convention.

Use of soybean protein hydrolysates for promoting proliferation of human keratinocytes in serum-free medium.

Human keratinocytes are generally cultured in media containing bovine pituitary extract (BPE), an animal product that can be a source of infectious contaminants. We investigated whether a safer plant product could replace BPE in the culture medium. Medium containing both BPE and soy protein hydrolysates (Bacto Soytone and Soy Hydrolysate) produced the largest number of viable cells, followed in descending order by medium supplemented only with BPE, only with the hydrolysates, and without supplementation (basal medium only). Soybean protein is thus an excellent source of nutrients for the growth of adherent keratinocytes, although they do not fully substitute for BPE.

A semantic inheritance/inverse-inheritance mechanism for systematic bio-ontology construction.

In this paper, we propose a semantic inheritance/inverse-inheritance mechanism for systematic bio-ontology construction. This mechanism allows domain experts to easily manage sophisticated bio-ontologies in which biological knowledge is encoded; it automatically captures semantics inferred from the ontology structure being constructed or already constructed. Based on the captured semantics it suggests appropriate recommendation to the experts. While inheritance enables them to consistently determine the semantics of relationships between ontology concepts (or classes), inverse-inheritance allows them to incrementally refine the semantics by exploiting a huge amount of relationships between the instances of the concepts. To demonstrate the feasibility of the mechanism, we also implement an OWL(Web Ontology Language)-based graphical bio-ontology management system. In the system, the mechanism is seamlessly applied to the ontology by well defined graphic notations based on OWL. OWL is adopted to fully express the subtle semantics inherently buried in the bio-ontology.

Cellular toxicity of various inhalable metal nanoparticles on human alveolar epithelial cells.

Nanoparticles (NPs) have a greater potential to travel through an organism via inhalation than any other larger particles, and could be more toxic due to their larger surface area and specific structural/chemical properties. The aim of this study was to evaluate in vitro biological effects of various inhalable metallic NPs (TiO2, Ag, Al, Zn, Ni). Human alveolar epithelial cells (A549) were exposed to various concentrations of NPs for 24 h. The extent of morphological damage was in the order of m-TiO2 > n-TiO2 > m-silica >> n-Ni approximately = n-Zn approximately = n-Ag approximately = n-Al and was affected in a dose-dependent manner. The extent of apoptotic damage measured with two-color flow cytometry was in the order of n-Zn > n- Ni > m-silica >> n- TiO2 > m- TiO2 > n-Al > n-Ag. The extent of apoptotic damage measured with DNA fragmentation was in the order of n-Zn approximately = m-silica > n- Ni >> m- TiO2 approximately = n- TiO2 approximately = n-Al > n-Ag, indicating no significant difference in the damages by both m-TiO2 and n-TiO2. The extents of apoptotic damages were also affected in a dose-dependent manner. Uptake of no other NPs but n-TiO2 and m-TiO2 into the cells was observed after 24 h exposure. The intracellular generation of ROS was significant with n-Zn but not with the other particles. These results demonstrated that various inhalable metallic NPs (TiO2, Ag, Al, Zn, Ni) could cause cell damages directly or indirectly. More detailed studies on the influence of size, structure, and composition of the NPs are needed to better understand their toxic mechanisms.

Distribution of dioxins, furans, and dioxin-like PCBs in solid products generated by pyrolysis and melting of automobile shredder residues.

Polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans, and dioxin-like polychlorinated biphenyls (PCBs) in char and slag produced from automobile shredder residue by pyrolysis and melting process were analyzed to measure changes in the characteristics and distribution of their congeners caused by thermal treatment. In particular, a large quantity of dioxin-like PCBs occurred in low-chlorinated congeners. The concentration of PCDDs/PCDFs in char was 0.542 microg/kg, with mostly PCDFs dominant and its toxicity equivalent concentration (TEQ) was about 70ngTEQ/kg. The concentration and toxicity equivalent concentration of dioxin-like PCBs in char were 0.869 microg/kg and 1.60ngTEQ/kg, respectively. Melted char slag was produced using various cooling methods: water quenching, air cooling, and slow cooling. The concentrations of PCDDs/PCDFs in slag produced by the methods were 1.51, 1.38, and 2.43ngTEQ/kg, respectively; those of dioxin-like PCBs were close to 0.01ngTEQ/kg. The congener distributions varied only slightly among the cooling methods. Applying melting procedure to char reduced PCDD/PCDF concentration by 95.3%, and the corresponding TEQ concentration was reduced by 97.9%. We thus conclude that melting process is an efficient way to reduce the concentrations of PCDDs/PCDFs in solids produced by pyrolysis.

Enrichment of PCDDs/PCDFs in the cooling system of municipal solid waste incineration plants.

This study measured the levels of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDDs/PCDFs), destroyed or formed in combustors and re-synthesized in cooling systems. For the proper control of PCDDs/PCDFs in municipal solid waste (MSW) incinerators, three grate-type MSW incinerators were selected, two of which had boilers, and one of which had a water spray tower (WST) as a cooling system. At the combustor outlets, dusts were in the range of 1640-4270 mg/Sm3 and PCDDs/PCDFs were in the range of 0.103-2.619 ng-TEQ/Sm3, showing the different values according to the grate structure of combustor and the flow direction of flue gas. After the flue gases passed through the cooling system, PCDDs/PCDFs at the waste heat boiler (WHB) outlets were enriched to levels that were 10.8-13.6 times higher than those at the furnace outlets, but PCDDs/PCDFs at the WST outlet was reduced to 5% of the level found at the furnace outlet. The emission patterns, such as the ratio of PCDFs to PCDDs, the ratio of gaseous-phase to particulate-phase PCDDs/PCDFs, and the compositional percentiles of each 2,3,7,8-substituted congener varied according to the types of air pollution control devices (APCDs). Reducing re-synthesis in the cooling system rather than enhancing the removal efficiencies of the APCDs seems to be more effective for lowering the levels of PCDDs/PCDFs in MSW incineration plants.

Effects of oxygen, catalyst and PVC on the formation of PCDDs, PCDFs and dioxin-like PCBs in pyrolysis products of automobile residues.

End-of-life vehicles are dismantled to recover reusable parts and then sent to a shredding facility for steel material recovery. The residue generated from the shredding process, so-called automobile shredder residue, is now being mostly disposed in landfill, however landfill will be prohibited in the near future. More recycling and energy recovery must be made by the regulation. The most appropriate method is the thermal treatment that will produce various forms of fuels and less volume of vitrified residue. In this research, an automobile shredder residue was simulated with considering the residue from a shredding factory based on the new vehicle and thermally treated by pyrolysis or gasification to observe the yields of gas, oil and char. In the temperature range of 400-800 degrees C, the yields of gas, oil, and char were 38.7-45.8%, 12.3-18.2%, and 36.0-49.0%, respectively. The optimum pyrolyzing temperature for more oil production was around 600 degrees C. Emission characteristics of the byproducts, PCDDs, PCDFs and dioxin-like PCBs were studied at the temperature of 600 degrees C. The analysis on the concentration and distribution of the isomers in various forms of the products were completed with and without oxygen, PVC, and catalytic metals, in order to observe how the existence of oxygen, PVC, and catalytic metals affect the formation of PCDDs, PCDFs, and dioxin-like PCBs from pyrolysis or gasification process. Without PVC, no PCDDs, PCDFs and dioxin-like PCBs were found in any products. PCDFs were predominant in any conditions. Catalyst and oxygen were found to affect to form more PCDDs, PCDFs, and dioxin-like PCBs. Effects of catalyst and oxygen on the byproduct formation seemed to be similar in oil and gas while that was different in char.

Management status of end-of-life vehicles and characteristics of automobile shredder residues in Korea.

An end-of-life vehicle (ELV) is dismantled to recover and recycle any re-usable parts, then shipped to the shredding facility for further recovery of iron with any remaining Automobile Shredder Residue (ASR) to be considered as wastes and to be disposed of by either thermal treatment or landfill. Overall ELVs management status in Korea, including recycling resulting from the dismantling processes, was surveyed using some questionnaires given to dismantlers and other available information to provide some feasible means for future treatment. The averaged recycle rate in the dismantling stage showed a value of 44% and the rest of an ELV was then compressed and transported to shredding companies to recover mainly the iron content which averaged 38.7% of the mass of a new vehicle. The non-ferrous metals such as copper, antimony, zinc and aluminum accounted for only 1.5%. The Shredder dusts (SDs) were found to be composed of light and heavy fluffs and soil/dust and amounted to 15.8% based on the mass of a new vehicle. Dumping of fluff and inorganic residues into a landfill site, however, will be restricted when new regulations are implemented to reduce the disposal amount to less than 5% of a new car as done in European countries and Japan. The detailed characteristics of SDs were investigated to provide an idea of how to treat them in order to meet a future expected enforcement.

Characteristics of ashes from different locations at the MSW incinerator equipped with various air pollution control devices.

The characteristics of ashes from different locations at a municipal solid waste incinerator (MSWI) equipped with a water spray tower (WST) as a cooling system, and a spray dryer adsorber (SDA), a bag filter (BF) and a selective catalytic reactor (SCR) as air pollution control devices (APCD) was investigated to provide the basic data for further treatment of ashes. A commercial MSWI with a capacity of 100 tons per day was selected. Ash was sampled from different locations during the normal operation of the MSWI and was analyzed to obtain chemical composition, basicity, metal contents and leaching behavior of heavy metals. Basicity and pH of ash showed a broad range between 0.08-9.07 and 3.5-12.3, respectively. Some major inorganics in ash were identified and could affect the basicity. This could be one of the factors to determine further treatment means. Partitioning of hazardous heavy metals such as Pb, Cu, Cr, Hg and Cd was investigated. Large portions of Hg and Cd were emitted from the furnace while over 90% of Pb, Cu and Cr remained in bottom ash. However 54% of Hg was captured by WST and 41% by SDA/BF and 3.6% was emitted through the stack, while 81.5% of Cd was captured by SDA/BF. From the analysis data of various metal contents in ash and leach analysis, such capturing of metal was confirmed and some heavy metals found to be easily released from ash. Based on the overall characteristics of ash in different locations at the MSWI during the investigation, some considerations and suggestions for determining the appropriate treatment methods of ash were made as conclusions.