The decomposition of NF3 using only an electron beam, and an electron beam in the presence of hydrogen are assessed in terms of the destruction and removal efficiency (DRE, %). Experiments were conducted at a flow rate of 500 LPM. The inlet concentration of NF3 in nitrogen gas was about 1,000 ppm, and the concentration of hydrogen ranged from 1,500to 8,000 ppm, respectively. Absorbed dose (kGy) and electric current ranged from 33.87 (5 mA) to 203.21 kGy (30 mA). The results in this study indicate that the DRE increased about 35% with hydrogen addition at electric current 30 mA. Additionally hydrogen gas played a significant role in the constituents of byproducts.
In 2010, amidst nationwide foot and mouth disease (FMD) outbreak and avian flu (AI), burial sites were urgently created for the disposal of animal carcasses. Some of the burial sites didn`t satisfy the carcass burial standard (e.g. too many carcasses were buried in one site, or size or location were not suitable), causing secondary environmental pollution including collapse of burial sites, contamination of ground water, soil and adjacent streams, and malodor. In this regard, there has been growing demand for measures to reduce the environmental impact of the burial sites and guidelines for designing and management of burial sites, considering domestic characteristics, to stabilize them. This study aims to acquire basic data to build pilot burial sites. To this end, we established lab scale reactors to analyze decomposition characteristics of buried bovine and swine carcasses and properties of leach ate and malodorous substances from them. The results showed that the decomposition of the samples inflated all reactors on its fifth day. But with time, as the volume of the samples decreased, the solum started to subside. In conclusion, at least 8 weeks was needed for the burial sites to stabilize. Malodorous substances, unlike other types of gas, were found to have relatively high content of sulfurous gases from 43 to 355 ppb. The four types of detected sulfurous gases were all classified as specific malodorous substances, producing rotting and unpleasant smell, irritating skin, eyes and the respiratory system, and damaging the central nervous system. Therefore, it is considered that controling sulfurous gases will play an important role in treating malodorous substances from burial sites.
The components of municipal solid waste incineration bottom ash produced over 3 million ton every year are similar to the components of geological features, therefore it is suitable to be used as the raw materials of lightweight aggregate. Development of lightweight aggregate using this bottom ash will be helpful to solve landfill and environmental problems. Lightweight aggregate was developed at 1,110oC by using clay, kaolin, bentonite and silica as the raw material to 50%of municipal solid waste incineration bottom ash. Silicon carbide (SiC) was used as a blowing agent. Optimal mixing ratio is bottom ash 50%, kaolin 22%, clay 22%, bentonite 6% and blowing agent 0.1%. As the result of quality test, produced lightweight aggregate met the all appraisal standards. The result of heavy metal leaching test was much lower than the elution reference value of ceramic manufactures made by using bottom ash.
In this study, the waste gasification gas was co-fired with LNG and water electrolysis gas (or stoichiometrically wellmixed hydrogen oxygen gas) in order to see the change of flame characteristics compared to the standard case of well known LNG flame. In detail, a numerical study was made to figure out the fundamental combustion characteristics of the waste produced gas blended LNG or hydrogen-oxygen mixture gas flame in an existing industrial LNG combustor. As a preliminary study, the mixture of 70% synthetic gas blended with 30% LNG or hydrogen-oxygen mixture gas was compared with pure LNG fuel with maintaining the same total input of heating value. Especially, the reason to include the hydrogen-oxygen mixture gas, that is, the mixture of H2 and 1/2 O2, as a fuel is following : the hydrogen-oxygen mixture gas has a rather high heating value since it does not need air as oxidizer, which consists of 79% N2 as inert material. The result shows that the case of mixture fuel with LNG exhibits more broadening flame shape than the 100% LNG flame. Further, it is observed that there is a phenomenon like a disappearance of CTRZ (Central Toroidal Recirculation Zone) and flame extinction showing partial lift-off of flame around strong swirl flow near burner. This kind of observation appeared in the case of blended fuel mixture is considered probably due to the increased effect of velocity and turbulence stress caused by the mass increase by the addition of low calorific fuel. However, the case of mixture fuel with hydrogen-oxygen mixture gas and water vapor does not show any flame instability phenomenon due to increased flow rate as in LNG case.
Anaerobically treated food wastewater still contains high concentration of organic carbon and nitrogen. Consequently, subsequent treatments are needed to meet the effluent criteria of wastewater. Injection of treated food wastewater into a waste landfill body could be one alternative for its subsequent treatment. In this study, preliminary experiments were conducted to inject treated food wastewater into waste landfill body. Firstly, Biochemical Methane Potential (BMP) test was conducted to evaluate the methane generation potential of the injected food wastewater. Secondly, anaerobically treated food wastewater showed clogging problem during the initial stage of laboratory scale lysimeter injection experiment. Accordingly, pretreatments were needed, and we experimented the change of viscosity of the wastewater after chemical injection (1 N acid or base solution) or aeration of wastewater. From the results, BMP for the treated food wastewater showed 373.8 mL CH4/g VS, which was 53% of untreated food wastewater`s. Practically feasible solution to reduce the viscosity of treated food wastewater was 1 day aeration before injection into the waste landfill body.
This paper presents the estimation of actual recyclable amounts and the evaluation of waste oil recycling processes at recycling facilities using material flow analysis (MFA). The estimation of actual recycling rates through the processes of waste lubricating oils is a very important subject not only in the point of view oil recycling efficiency by energy conversion processes but also in the perspective of the recycling technology level. In this study, the recycling processes and recycling rates of waste lubricating oil recycling facilities were evaluated by using a MFA approach, a total of 10 site visits and a total of 30 site questionnaires in Korea. The MFA methodology based on mass balance approach applied to identify the inputs and outputs of waste oils during the recycling processes at waste oil recycling facilities. It is necessary to determine the composition and flows of the input materials to be recycled and foreign substances in a waste recycling facility. A complete understanding of the waste flows in the processes along with the site visit and data surveys for the recycling facilities was required to develop a material flow for the processes and determine the process yield by different treatment methods (chemical distillation, vacuum distillation and high temperature pyrolysis). The results show that on average the process yields for chemical distillation, vacuum distillation, and high temperature pyrolysis were 89.9 ± 7.7%, 77.9 ± 16.1%, and 57.9 ± 9.3%, respectively. During the chemical distillation method, water in waste oils was a major fraction (> 50%), while the vacuum distillation method resulted oil large amounts of oil sludge produced during the recycling process. The process yields for different treatment methods depended upon several factors including the quality of incoming waste oils, the type and operating conditions of recycling processes that are applied to. Based on the material flow analysis in this study, the actual recycled amount of waste oil was estimated to be approximately 260,809 ton in 2011.
This paper examined energy consumption distribution by process and energy production-effect of MBT facilities in Korea. Generally, facilities that use fossil fuels for drying consumed energy about 70 ~ 80% in drying and exhaust gases treatment process and energy distribution was heavily affected a position of drying and a kind of fuel. Energy production effect by the ratio of input-energy to output-energy ranged from 4.54 to 9.60, however, if generation efficiency is reflected, it was standardized to low levels from 3.10 ~ 3.77. So we were able to confirm that the superiority of energy production effect between facilities is not considerable.
This study provides a result of thermal mercury reduction for inventing a mercury recovery technology from the sludge which contains high concentration of mercury. Physical, chemical and thermal properties of the sludge were analyzed and mercury degradation at elevated temperatures was investigated to find out the optimum temperature range for thermal recovery of mercury from the sludge generated from an industrial facility, which contained high concentration of mercury. The study was carried out in the temperature range of up to 650℃ from 200℃, and 500 ~ 710 μm particle size of waste sludge samples were selected from such industries. As primary thermal tests the sludge was heated up to observe weight degradation at a continuous weight measurable thermo gravimetric analyzer and a muffle furnace and the degradation curves from both devices were found to be well matched. Mercury conversion to gaseous form was investigated from the analyzed data of mercury concentrations sampled every 25℃ from a muffle furnace. Cold vapor atomic absorption spectroscopy (CVAAS) Hg analyzer was used for the analysis of mercury content in solid and liquid samples. Most of mercury was degraded and released as gas phase at the temperature range from 300℃ to 550℃, which could be the optimum temperature of mercury recovery by thermal method for the sludge containing high concentration of mercury. Based on these thermal mercury reduction studies, degradation kinetics study of mercury was conducted to provide the reaction kinetics data for further reactor design to recover mercury using a thermal method.
In order to cope with resource depletion and global warming, many countries around the world are seeking the technical land political alternatives and are focusing on production of refuse derived fuel (SRF) as a viable approach. SRF is classified into pellet SRF and fluff SRF based on the shape. In domestic trend, Pellet RDF has been mainly produced until now, but as the quality standard of fluff SRF was set up lately, it is expected to raise supply and demand on Fluff SRF after this. Fluff SRF is a solid fuel not to be processed pelletizing step, and has advantages that manufacturing process is simple and economical. In this paper, we selected 3 MBT plants to produce Pellet SRF in Korea and examined reduction effects of energy and CO2 emission by conversion of pellet SRF to fluff SRF. As a result, the saving energy by the conversion of SRF type is 2,509 Gcal/yr (A), 1,716 Gcal/yr (B) and 1,210 Gcal/yr (C) respectively, and the reduction rate of energy consumption in full process is about 23% ~ 26% by comparison with pellet SRF. Also, the average of reduction of CO2 emission per unit of MSW is 0.0272 tCO2/ton. After estimating the reduction of CO2 emission of 9MBT plants in Korea, based on the results of a survey of target plants, we concluded that the reduction effect of CO2emission is created 11,374 tCO2/yr.
This study investigated the prospective increase in the amount of hazardous substances in packing containers. Thestudy`s aim was to analyse phthalates, which are regulated for use in food containers in the EU, as well as four heavy metals (Pb, Cd, Hg, and Cr6+) regulated domestically and abroad. Furthermore, we endeavored to confirm the need for additional regulations for packaging material by analysing PBDEs (Polybrominated diphenyl ethers), a brominated flame retardant that has recently become an issue because of its wide use in plastic packaging. The concentration of the heavy metal, namely Pb, Cd, Hg and Cr6+ in packaging material samples were in ranged from ND to 7.2 mg/kg, ND to 0.47mg/kg, ND to 0.07 mg/kg, and ND to 5.01 mg/kg, respectively. With total concentration of the four heavy metals (ΣPb +Cd + Hg + Cr6+) ranging from ND to 9.14 mg/kg, all samples were below the standard threshold (Σ 100 mg/kg). The concentration of phthalates in packaging samples was less than the standard of all foreign nations of 0.1% (1,000 mg/kg). In particular, DEHP, DEHA, and DBP were detected higher in smart phone cases than others; other materials were found to be at similar levels. The concentration of PBDEs in packaging material samples was detected in the range of ND to 24.2 mg/kg, thereby not exceeding the standard of WEEE and RoHS of 0.1% (1,000 mg/kg) for electrical appliances and electronics.
Considering possibility of public health risk and environmental hazards, it is important to manage the disposal of "medical waste" properly. Although Korean government has made many efforts to provide safe medical waste management system, some institutional problems are still existing and need to be improved. We focused on medical waste management in emergency situations. Currently, the most common method of medical waste disposal is off-site incineration, which accounts for approximately 99.6% of total waste. However, in case some incineration facilities stopped unexpectedly because of fire, strike, breakdown, etc., inappropriate management of the medical waste has been of important environmental concern due to potential secondary infection. This paper presents current limitations of resignment-related regulation and suggests improvement methods for effective and safe treatment of the medical waste, especially in emergency situations.
The present study was conducted to provide basic data for efficient vermin composting of swine manure by investigating the effect of rice hull mix on growth and reproduction of earthworms, amount of earthworm cast produced, and its chemical composition when mixing swine manure in different levels (0 (SRH0), 10 (SRH10), 20 (SRH20), 30 (SRH30), and 40%(SRH40)) with rice hull commonly used as a bulking agent for facilitation in manure composting. The C/N ratio of the feed was 10.19-13.95 and increased with higher level of rice hull mixed, and the survival rate of earthworms during the experiment period was 35.2-99.2%. The biomass growth rate of earthworms was significantly higher in the SRH30 andSRH40 treatments than others (p < 0.05), and young worms were not found in any treatments, but the number of cocoons was 7.4 in the SRH40 treatment. The production of earthworm cast and digested amount were higher with the higher level of mixed rice hull (p < 0.05), and the C/N ratio of cast increased with the mixed rice hull ratio, being significantly higher ratio in SRH40 than other treatments (p < 0.05). Among heavy metals, the copper content tended to decrease with the mixed rice hull level. To summarize, the higher level of mixed rice hull was associated with improvement in growth, reproduction, and cast production of earthworms, and 30-40% rice hull mix in particular could result in efficient vermicomposting.
Mercury distribution and hazardous characteristics of major components from SCFLs (Spent compact fluorescent lamps)for 3 lamp manufactures (A, B, C) are estimated by the analysis of mercury concentration and leaching tests such as Korean Extraction Test (KET) and Toxicity Characteristic Leaching Procedure (TCLP). SCFLs can be separated into glass tube, phosphor powder, metals, ballast, plastics, and binder. Through the analysis of mercury in major components for SCFL, mercury concentration in phosphor powder is much higher than that in other components regardless manufactures of lamp. Also, mercury concentration in phosphor powder is dependent of the manufactures of lamp. From the leaching tests, all components except phosphor powder from 3 lamp manufactures are verified to be non-hazardous waste because all leaching concentrations are below the regulatory level. However, the leaching concentration of mercury in phosphor powder of SCFLs is higher than the regulatory level in both KET and TCLP regardless manufactures of lamp. Hence, phosphor powder should be managed as a hazardous waste and should be separately managed to control mercury
Geopolymer foam block was prepared and its characteristics discussed to evaluate the possibility of replacing blast furnace slag (below BFS) with melting slag in this study. 10 ~ 20wt% of BFS was replaced with melting slag. And also10wt% of mine tailing was replaced with fly ash discharged from municipal solid waste incinerator (below MSWI). The compressive strength of foam block prepared was similar to that of foam block prepared without replacing BFS. And also it was increased by replacing 10wt% of mine tailing with MSWI fly ash. Considering these results, melting slag maybe used instead of BFS without damaging the quality of foam block.