• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.2D
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• pp.143-151
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• 2010

Currently, one of the most interested things at home and abroad country will be an eco-friendly construction. Among these, one of the most important elements will be the recycle and reuse of construction and demolition waste. Because construction waste is generated the most at the demolition phase, it is important to minimize the quantity of the demolition waste at the phase. And it is also important to develop a system to manage rightly the generated demolition waste. But in the domestic country, a research for this has hardly been carried out. In recent, the government has realized its importance and is making a research to improve demolition technique and is preparing a research to make a raw for deconstruction. Therefore, this study examined its application situation and importance by analyzing the trend of demolition technique used in the domestic industry. Also this study carried out a survey for situation analysis of the demolition industry. This study suggested items needed for the development of demolition technique, demolition design and reduction of C&D waste through a survey results and a situation analysis.

• Environmental Engineering Research
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• v.23 no.3
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• pp.258-264
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• 2018

The objectives of this research were to 1) isolate and identify thermophilic bacteria for food waste treatment; 2) investigate the capability of food waste treatment using Bacillus species; and 3) develop air-dried Bacillus starters for food waste treatment. Five Bacillus species were isolated from food wastes and identified as Bacillus licheniformis (B. licheniformis) G1, Bacillus circulans C2, Bacillus subtilis (B. subtilis) E1, Bacillus vanillea F1, and Bacillus atrophaeus G2 based on 16S rDNA sequencing. Each identified Bacillus and the mixture of Bacillus species were cultivated in the standard food waste at $45^{\circ}C$ for 8 d. Changes in cell count, solid contents, and pH of the food waste were monitored during cultivation. Air-dried Bacillus cell powders were prepared using wheat flour and lactomil as excipients, and the cell count and survival rate were determined. The cell count of B. licheniformis G1 exhibited the highest number among the tested Bacillus (${\sim}10^8CFU/mL$). The greatest reduction in solid contents of food waste was achieved by B. subtilis E1 (22.6%). The mixture of B. licheniformis G1 and B. subtilis E1 exhibited a synergistic effect on the reduction of solid contents. Lactomil was determined as better excipient than wheat flour based on the greatest survival rate of 95%.

• Journal of Powder Materials
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• v.24 no.1
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• pp.34-40
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• 2017

This study is carried out to obtain basic data regarding oxidation and reduction reactions, originated on the recycling of waste tungsten hard scraps by oxidation and reduction processes. First, it is estimated that the theoretical Gibbs free energy for the formation reaction of $WO_2$ and $WO_3$ are calculated as ${\Delta}G_{1,000K}=-407.335kJ/mol$ and ${\Delta}G_{1,000K}=-585.679kJ/mol$, from the thermodynamics data reported by Ihsan Barin. In the experiments, the oxidation of pure tungsten rod by oxygen is carried out over a temperature range of $700-1,000^{\circ}C$ for 1 h, and it is possible to conclude that the oxidation reaction can be represented by a relatively linear relationship. Second, the reduction of $WO_2$ and $WO_3$ powder by hydrogen is also calculated from the same thermodynamics data, and it can be found that it was difficult for the reduction reaction to occur at $1,027^{\circ}C$, in the case of $WO_2$, but it can happen for temperatures higher than $1127^{\circ}C$. On the other hand, $WO_3$ reduction reaction occurs at the relatively low temperature of $827^{\circ}C$. Based on these results, the reduction experiments are carried out at a temperature range of $500-1,000^{\circ}C$ for 15 min to 4 h, in the case of $WO_3$ powder, and it is possible to conclude that the reduction at $900^{\circ}C$ for 2h is needed for a perfect reduction reaction.

• Journal of the Korea Institute of Building Construction
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• v.17 no.3
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• pp.269-277
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• 2017

In this work, as a preliminary experimental works, which focuses on utilizing separated pastes from activated (or radioactive) concrete as solidifying agents for radioactive waste immobilization, were performed. It was found that density of hydrated cement paste, which was lower than that of ordinary portland cement, increased as temperature for heat treatment increased. Highest compressive strength was observed with the specimens that was heat treated at $600^{\circ}C$. However, heat treatment over $700^{\circ}C$ showed higher CaO content that caused higher heat of hydration after in contact with water, lows of workability, and lower strength. Based on experimental results, it is suggested that $600^{\circ}C$ heat treatment is more appropriate for waste cement paste to be used as a solidifying agent.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.12
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• pp.3761-3767
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• 2009

This study was investigated to determine the combustion characteristics, decomposition efficiency, and the flue gas concentrations after combustion in the high temperature reactor($1,250{\sim}1,400^{\circ}C$, 1 atm) for the liquid wastes(waste oil and waste solvent) generated from the industrial complex. The concentration of nitrogen oxide(NOx) is decreased and the synthetic gas is increased when the mass ratio of $O_2$/waste is about 1.53 because the reaction condition was changed to reduction state. And BTEXs(benzene, toluene, ethylbenzene, xylene) are decomposed more than 99.99%. If the highly concentrated liquid waste (waste oil and waste solvent) is treated under the operating conditions suggested by this study, our treatment method for the liquid waste was found to be proper because of the contaminants emission concentration is very low. In addition, the synthetic gas after combustion can be used as an alternative fuel.

• Environmental Engineering Research
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• v.23 no.3
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• pp.323-329
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• 2018

The municipal solid waste (MSW) management system in one of the Class II Indian cities i.e. Rishikesh was studied and analysed to identify the key issues in solid waste management in the city. A total of 329 solid waste samples from 47 households were collected to characterize the household solid waste (HSW). The average (HSW) generation rate was 0.26 kg/c/d and it was composed of organic waste (57.3%), plastics (14%), paper (10.9%), and glass and ceramic (1.3%) and other materials (16.5%). There was an inverse relationship between household waste generation rate and family size (p < 0.05). The MSW management system practiced in Rishikesh is unsound. There is no waste segregation at source, no provisions of composting and no recycling by formal sector. The collection and transportation of waste is inadequate and inappropriate. Collected waste is dumped in open dumping site without scientific management. Following are some recommendations for developing a sustainable solid waste management system in Rishikesh city: (1) sensitize people for segregation at source; (2) promote reduction, reuse and recycling of wastes; (3) promote community based composting; (4) provision for 100% door to door collection and; (5) formalize the informal sectors such as rag pickers and recycling industries.

• Resources Recycling
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• v.7 no.2
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• pp.39-45
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• 1998

We smelted thc pellets made by mixing the distilled carbon from wlISte Lires, LD converter dust and slag with reduction process in the revcrberatory furnace. Thc obtained results are as follows 1) The removal mte of zinc appears above 97% after T reducing the pellets at $1300^{\circ}C$ for Ihr and the zinc content in the residue are 0.1~D.2%. 2) Under the mixing condition of 500 g LD dust. 150-200 g LD slag and 30-50 g distilled carbon of waste lires the removal raho of zinc shows above 95%, while t the 50-60% Fe remains in the residue. 3) After smelting at $1350^{\circ}C$ for 3hrs, the recovery ratio of pig iron reduced from lhe p pellets containing 15-20% LD slag and 4.1-7.2% distilled carbon of waste tires appears in the range of 89.3-92%. 4) Tbe c chemical composition of the recovered pig iron is 1.7%C, O.05%P, 0.05%S and balance Fe. 5) Tbe recovered dust from the d dust collcctor alter finishing the reduction rcaction appears as a crude zinc oxide conLaining 60% zinc.

• Particle and aerosol research
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• v.15 no.1
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• pp.1-13
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• 2019

Current desulfurization and denitrification technologies have reached a considerable level in terms of reduction efficiency. However, when compared with the simultaneous reduction technology, the individual reduction technologies have issues such as economic disadvantages due to the difficulty to scale-up apparatus, secondary pollution from wastewater/waste during the treatment process, requirement of large facilities for post-treatment, and increased installation costs. Therefore, it is necessary to enable practical application of simultaneous SOx and NOx treatment technologies to remove two or more contaminants in one process. The present study analyzes a technology capable of maintaining simultaneous treatment of SOx and NOx even at low temperatures due to the electrochemically generated strong oxidation of the wet-pulse complex system. This system also reduces unreacted residual gas and secondary products through the wet scrubbing process. It addresses common problems of the existing fuel gas treatment methods such as SDR, SCR, and activated carbon adsorption (i.e., low treatment efficiency, expensive maintenance cost, large installation area, and energy loss). Experiments were performed with varying variables such as pulse voltage, reaction temperature, chemicals and additives ratios, liquid/gas ratio, structure of the aeration cleaning nozzle, and gas inlet concentration. The performance of individual and complex processes using the wet-pulse discharge reaction were analyzed and compared.

• Environmental Engineering Research
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• v.22 no.3
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• pp.237-244
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• 2017

At present, in India, handling of solid waste has become a major challenge for the municipal authorities. Composting of solid waste, especially organic waste, can be one of the solutions to tackle the issue of handling solid waste. The present study is focused on agitated piles composting of flower waste (FW). Five combinations of FW with dry leaves (DL) and cow dung (CD) were prepared to conduct the study. Significant changes were observed due to the addition of bulking agent. The bulking material helps to reduce the production of leachate and also to maintain the aerobic condition within the piles. The reduction of total organic carbon was 21% in FW composting which increased by 36.48% during the composting of FW on addition of DL and CD. On the 120th day of composting, the pH of pile five (70 kg FW + 20 kg CD + 15 kg DL) was 7.33, electrical conductivity 2.77 mS/cm, total organic carbon 26.9%, total nitrogen 2.2%, and C:N ratio was 12. Appropriate proportion of waste mixture played an important role in providing favorable conditions for the microbial transformation of flower waste to stabilized compost. Finally, FW with the combination of CD and DL was found to be successful during pile composting.

• Korean Chemical Engineering Research
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• v.48 no.1
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• pp.39-44
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• 2010

Economic feasibility of power generation system using waste woody biomass in a circulating fluidized bed combustor has been investigated. Effects of important variables such as capital investment, cost of waste wood, certified emission reduction(CER), system marginal price(SMP) on the benefit of business have been analyzed. Internal rate of return(IRR) was predicted as 16.67%, which implicates the business is promising based on the assumptions such as SMP of 99 Won/kWh, capital cost of 10.65 billion won, and complimentary providing of waste wood. Major factors affecting the benefit of business were as follows; system marginal price, operational rate, capital investment, expenditure of waste wood, certified emission reduction. In addition, it must be necessary to consider CHP power plant providing steam as one of the means to diversify sales network, for the management of the business risk.