• Environmental Engineering Research
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• v.22 no.1
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• pp.1-11
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• 2017

One of the most threatening consequences of eutrophic freshwater reservoirs is algal blooming which typically occur after the long a mega drought or/and irregular rainfall under influence of climate change. The long-term experiences of chemical treatment are known as a most practical effort to reduce health concerns from human exposure of harmful cyanobacteria as well as to preserve ultimate freshwater resources. Even though these conventional chemical treatment methods do not completely solve the algal residue problem in water treatment plant or directly in the water bodies, they still have big advantages as fast and efficient removal process of cyanobacteria due to cheaper, easier to manage. This review summarizes their chemical treatment scenarios of the representative coagulants, pre-oxidants and algaecides composed to chemical compounds which immediately may help to manage severe cyanobacteria blooms in the summer seasons.

• Journal of the Korean Geotechnical Society
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• v.21 no.3
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• pp.79-85
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• 2005

An experimental study was carried out to investigate the recycling possibility of waste oyster shells, which induce environmental pollutions by piling up out at the open or the temporary reclamation. The purpose of this study is to develope eco-friendly binder using waste oyster shells, and to reinforce dredged soils fur soft soil improvement. In this paper, a series of laboratory tests including compressive strength tests were performed to evaluate strength characteristics of soils treated by developed binder with different water content of dredged soils, mixing rates of binder, curing days. Based on test results, eco-friendly binders manufactured from waste oyster shells were estimated as good resource materials for soft soil improvements.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.553-560
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• 2005

An experimental investigation was carried out to study recycling possibility of waste oyster shells, which induce environmental pollutions from piling up out at the open or the temporary reclamation. The purpose of this paper is to develop eco-friendly binder using waste oyster shells, and to investigate their reinforcing effects for dredged soil improvement. A series of laboratory tests including compressive strength tests were performed to evaluate strength characteristics of soils treated by developed binder with varying water content of dredged soils, mixing rates of binder, and different curing days. Based on laboratory test results, eco-friendly binders developed here using waste oyster shells were found as good resource materials for soft soil improvements.

• Proceedings of the Korean Institute of Resources Recycling Conference
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• 2006.09a
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• pp.15-32
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• 2006

Biomass had been attracted public attention as eco-friendly resource which not increases the greenhouse gas like carbon dioxide. In this study, it had been collected pyrolytic products such as bio-oil, char and pyrolytic gas from various biomass in a fluidized bed reactor which is one of the fast pyrolysis processes. To understand the characteristics of biomass pyrolysis, the variation of products yield and chemical composition was determined with various operating parameters like temperature, gas velocity($U_{0}/U_{mf}$) and bed height(L/D). In the optimum operating conditions, gas yield and water content was the lowest and concentration of guaiacols and syringols were the highest. The maximum yields of bio-oil was from 55% to 58% at $400^{\circ}C$.

• Resources Recycling
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• v.32 no.2
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• pp.12-18
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• 2023

In 2018, the demand for silver (referred to as Ag) in the electrical and electronics sector was 249 million tons. The demand stood at 81 million tons in the solar module production sector. Currently, due to the rapid increase in solar module installation, the demand for silver is increasing drastically in Korea. However, Korea's natural metal resources and reserves are insufficient in comparison to their consumption, and the domestic silver ore self-sufficiency rate was as low as 2.2% as of 2021. This implies that a recycling technology is necessary to recover valuable metal resources contained in the waste plating solution generated in the metal industry. Therefore, this study compared and analyzed, the results of the impact evaluation through life cycle assessment according to an improvement in the process of recovery of valuable metals in the waste plating solution. The process improvement resulted in reducing GWP (Global Warming Potential) and ADP(Abiotic Depletion Potential) by 50% and 67%, respectively. The GWP of electricity and industrial water was reduced by 98% and 93%, respectively, which significantly contributed to the minimization of energy and water consumption. Thus, the improvement in recycling technology has a high potential to reduce chemical and energy use and improve resource productivity in the urban mining industry.

• Journal of the Korea Organic Resources Recycling Association
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• v.10 no.3
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• pp.98-109
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• 2002

Each kinds of the leather process wastes which is occurred in the leather making process is almost more than 50% on the basis of the raw hide. The emitted process wastes are important oil and fats and protein resources because they are composed of animal oil and fats and fibrous protein. But most of them are incinerate or filled up simply as the industrial wastes without applying to recycling into the other use. Thus the problems of environmental pollution are becoming more critical and the processing cost of the leather process wastes (40,000~60,000 won) is a heavy burden on the production cost. Because the organic wastes such as fleshing scrap, pelt scrap are high fetid, its unlawful abandonment without being processed properly causes the occurrence of secondary pollution by an offensive odor and leakage of waste water. Thus we made the re-resource experiments in order to resolve this problems. The principal contents of this study are to process the collected leather waste scrape through separate the oil and fat ingredients with various propert by processing various chemicals and enzymes on the next effector. The re-resource application of separated oil and fat ingredients produced chemical for leather applicable to manufacturing process of leather through chemical transformation process(sulphation reaction, sulphitation reaction etc.) of oil and fats.

• Resources Recycling
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• v.31 no.2
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• pp.40-48
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• 2022

In this study, the effects of solution components were investigated in the recovery of vanadium as ammonium metavanadate from vanadium-ore-salt roasting-water leaching solution. The vanadium-containing solution is strongly alkaline (pH 13), so the pH must be lowered to 9 or less to increase the ammonium metavanadate precipitation efficiency. However, in the process of adjusting the solution pH using sulfuric acid, aluminum ions are co-precipitated, which must be removed first. In this study, aluminum was precipitated in the form of an aluminum-silicate compound using sodium silicate, and the conditions for minimizing vanadium loss in this process were investigated. After aluminum removal, the silicate was precipitated and removed by adjusting the solution pH to 9 or less using sulfuric acid. In this process, the concentration and addition rate of sulfuric acid have a significant influence on the loss of vanadium, and vanadium loss was minimized as much as possible by slowly adding dilute sulfuric acid. Ammonium metavanadate was precipitated using three equivalents of ammonium chloride at room temperature from the aluminum-free, aqueous solution of vanadium following the pH adjustment process. The recovery yield of vanadium in the form of ammonium metavanadate exceeded 81%. After washing the product, vanadium pentoxide with 98.6% purity was obtained following heat treatment at 550 ℃ for 2 hours.

• Environmental Engineering Research
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• v.19 no.3
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• pp.185-195
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• 2014

Despite the enormous technical and economic efforts to improve environmental conditions, currently about 40% of the global population (or 2 billion people) are still lack access to safe water supply and adequate sanitation facilities. Pollution problems and transmission of water- related diseases will continue to proliferate. The rapid population growth and industrialization will lead to a reduction of arable land, thus exacerbating the food shortage problems and threatening environmental sustainability. Natural systems in this context are a transdisciplinary approach which employs the activities of microbes, soil and/or plants in waste stabilisation and resource recovery without the aid of mechanical or energy-intensive equipments. Examples of these natural systems are: waste stabilisation ponds, aquatic weed ponds, constructed wetlands and land treatment processes. Although they require relatively large land areas, the natural systems could achieve a high degree of waste stabilisation and at the same time, yield potentials for waste recycling through the production of algal protein, fish, crops, and plant biomass. Because of the complex interactions occurring in the natural systems, the existing design procedures are based mainly on empirical or field experience approaches. An integrated kinetic model encompassing the activities of both suspended and biofilm bacteria and some important engineering parameters has been developed which could predict the organic matter degradation in the natural systems satisfactorily.

• Culinary science and hospitality research
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• v.11 no.3 s.26
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• pp.121-137
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• 2005

Today's rapid industrialization and population concentration in cities lead to a vast economic growth, and consequently, people's increased desire of spending demands abundant and diverse food. As a result in Korea, annual food waste is 4.1 million tons (24.6% of household waste) and daily food waste amount to 11,397 tons which is equivalent to 1,400 loads of 8-ton truck. It is best to recycle toed waste as manure, forage, and fuel than reclamation but separate collection of food waste is very difficult by reason of water content. So only a little portion of food waste from large-scaled restaurants and cafeterias that handle food waste relatively well. requirement for recycling food wastes into forage and manure needless to say, reduction activity is best way. Therefore, large-scaled restaurants and cafeterias need to seek plans to minimize food resource waste thus reducing the cost and waste processing cost by implementing appropriate reduction program.

• Industry Promotion Research
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• v.1 no.1
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• pp.143-149
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• 2016

This study verified the relationship on the perception of water reuse R&D support and water reuse vitalization policy. The study results showed that the perception of water reuse importance and effectiveness positively affected the perception of the necessity of water reuse vitalization policy, necessity of supporting water reuse water-saving product company, necessity of investing water reuse(p<.001). Also, gender, education, occupation, type of residence and monthly water rate significantly affected the between-group differences of the perception of water reuse vitalization policy. This study provided implications for preparing water reuse investment and vitalization policy by the relationship on the perception of water reuse R&D support and water reuse vitalization policy.