장성호 Seong-ho Jang , 김고은 Go-eun Kim , 배종명 Jong-myeong Bae , 이병인 Pyong-in Yi , S. Sivakumar , 정은상 Eun-sang Jung , 이재용 Jae-yong Lee , 박진식 Jin-sick Park , 류재용 Jae-yong Ryu

DOI:10.9786/kswm.2017.34.8.761

Abstract

As industry continues to develop, the amount of various recalcitrant substances that cannot be removed by conventional wastewater treatment has increased in modern society. The SCFs (Soluble Cutting Fluids) used in metalworking processes contain many chemical substances, such as mineral oils, anticorrosive agents, extreme-pressure additives and stabilizers, as well as high concentrations of organics. Recently, electrolysis has been expected to become an alternative to conventional processes and to be useful in various wastewater treatments. Electrolysis is a highly adaptable industrial wastewater treatment method, having a high efficiency, short processing time, and simple equipment composition, regardless of the biodegradable nature of the contaminants. The effects of operating time, current density, and electrolyte on COD removal of waste SCFs have been studied using the stainless steel (SUS316) electrode in a batch type reactor. The results were as follows. ① Without electrolytes, when the current density was adjusted to 40 A/㎡, 60 A/㎡, and 80 A/㎡, the removal efficiencies of the COD were 25.0%, 37.7%, and 49.1% after 60 min, respectively. ② In the comparison between NaCl (5 ~ 10 mM) addition and non-addition, the removal efficiency with NaCl was higher than for without after 60 min for all current densities. ③ In the comparison between Na₂SO₄ (5 ~ 10 mM) addition and nonaddition, the removal efficiency with Na₂SO₄ showed no significant difference to that with NaCl at all current densities.

Key Words

COD, Electrolysis, Stainless, Soluble Cutting Fluids (SCF)

양회원 Hoiweon Yang , 안조환 Johwan Ahn , 김장호 Jangho Kim , 민성재 Sungjae Min , 김정환 Junghwan Kim

DOI:10.9786/kswm.2017.34.8.768

Abstract

This study was conducted to investigate the feasibility of nutrient recovery and reuse from centrate, which was produced by the centrifugal dewatering of anaerobic digested sludge. A continuous stirred reactor was operated for 3 months to recover phosphorous and nitrogen as magnesium ammonium phosphate (MAP) crystals from the centrate. More than 95% of phosphate could be recovered from the centrate into the crystalline materials. The contents of TP and TN in the crystalline materials were 28.1% and 5.17%, respectively. Some heavy metals were identified, but remained under Korean standards for organic fertilizer. On the other hand, X ray diffraction analysis clearly showed that the crystalline materials was MAP crystals. However, chemical analyses suggested that some undesirable crystals like magnesium potassium phosphate or hydroxyapatite might be formed during the MAP crystallization. Nevertheless, both results strongly confirmed that the MAP crystals could be a useful and valuable nutrient fertilizer, which slowly and continuously releases essential nutrients in response to the demand from farming and planting.

Key Words

Anaerobic digested sludge, Centrate, Magnesium ammonium phosphate (MAP), Nutrient recovery, Reuse

유흥민 Heung-min Yoo , 엄남일 Nam-il Um , 김용준 Yong-jun Kim , 조윤아 Yoon-a Cho , 신선경 Sun-kyoung Shin , 김기헌 Ki-heon Kim

DOI:10.9786/kswm.2017.34.8.776

Abstract

By the end of 2012, the recycled proportion of domestic waste tires was 287,330 ton (93.9%) of the amount of waste tires discharged (305,877 ton). The waste tires have been reused for heat supply, material recycling and other purposes; the proportions are 50.1%, 20.7% and 23.1%, respectively. In the case of heat supply, waste tires are supplied to cement kiln (104,105 ton, 68%), RDF manufacture facilities (47,530 ton, 31%) and incinerators (1,923 ton, 1%). Recently, there has been an increase in the use of waste tires at power generation facilities as an auxiliary fuel. Thus, physico-chemical analysis, such as proximate analysis, elemental analysis and calorific value analysis have been carried out to evaluate potential of waste tires as an auxiliary fuel in Korea. The LHV (Lower Heating Value) of waste tires is approximately 20% higher than that of coal, at an average of 8,489 kcal/kg (7,684 ~ 10,040 kcal/kg). Meanwhile, the sulfur content is approximately 1.5wt. %, and balance of plant (e.g. pipe line, boiler tube, etc.) may be corroded by the sulfur. However, this can be prevented by construction and supplementation with refractories. In this study, TDF (Tire Derived Fuel) produced from waste tires was co-combusted with coal, and applied to the CFB (Circulating Fluidized Bed) boiler, a commercial plant of 100 tons/day in Korea. It was combined with coal, ranging from 0 to 20wt. %. In order to determine the effect on human health and the environment, gas emission such as dioxin, NOx, SOx and so on, were continuously analyzed and monitored as well as the oxygen and carbon monoxide levels to check operational issues.

Key Words

Waste tires, TDF (Tire Derived Fuel), Dioxin, TDF/coal Co-combustion, CFB (Circulating Fluidized Bed)

장성호 Seong-ho Jang , 정영빈 Young-been Jeong , 배종명 Jong-myeong Bae , 홍성철 Sung-chul Hong , 서정민 Jeong-min Suh , 이병인 Pyong-in Yi , 이재용 Jae-yong Lee , 박진식 Jin-sick Park , 문추연 Choo-yeun Moon

DOI:10.9786/kswm.2017.34.8.784

Abstract

The mother machine makes the necessary shape by processing materials such as metal. The SCFs are applied to the processing surface when the mother machine processes the material, thereby improving the cutting conditions. SCFs contain high concentrations of organic components and nitrogen compounds, which can cause problems such as eutrophication and algae bloom. Therefore, proper treatment is required. Electrochemical treatment is expected to be an alternative to conventional processes, and to be useful in various wastewater treatments. Moreover, it is an efficient elimination technique for contaminants and has a simple equipment composition. In this study, the removal efficiency of the T-N contained in the waste SCF using electrochemical treatment is analyzed. The electrode was made of titanium and iridium, made into a perforated metal sheet to prevent an imbalance of the sample concentration in the reactor. Experiments were conducted to examine the effects of current density and the concentration of the supporting electrolyte (NaCl, Na₂SO₄) on removal efficiency. In the cases with 60 A/㎡, 80 A/㎡, and 100 A/㎡ current densities, the removal efficiencies of the T-N contained in the waste SCF were 51.03%, 68.83%, and 79.58%. Comparing between the addition and non-addition of NaCl, the removal efficiency with the addition of NaCl (5 ~ 10 mM) was higher than for no addition at 60 min for all current densities. The addition of Na₂SO₄ increased the removal rate of the T-N, but it was less effective than NaCl addition.

Key Words

Wasted soluble cutting fluids, Electrochemical treatment, Ti/Ir electrode, T-N

김용준 Yong-jun Kim , 황동건 Dong-gun Hwang , 오정근 Jung-keun Oh , 조윤아 Yoon-a Cho , 신선경 Sun-kyoung Shin , 김기헌 Ki-heon Kim

DOI:10.9786/kswm.2017.34.8.791

Abstract

The purpose of this study is to understand the current situation for waste generation from domestic industries and to calculate the designated waste generation containing heavy metals using Korean waste statistics. Analytical data regarding heavy metals for hazardous waste in a previous study was reviewed. In addition, the designated waste generation for each heavy metal was estimated by comparing the data of the Allbaro system (2014). The designated waste generations were, in order, Pb > CN-> Cd > Cu > Hg > Cr⁶⁺ > As, and the sludge, ash, slag, dust, etc. generated from the process of wastewater treatment, plating and anodizing of metals, waste treatment, and the manufacture of basic iron and steel, considered as designated waste containing heavy metals, were investigated. The waste generation with heavy metals was 1.812 % of the total waste generation, which is higher than the 1.317 % collected from the Allbaro system (2014). These results will be used as a baseline in establishing waste management policy. Further analytical data about heavy metals in the designated wastes that are mentioned in this study are required for a more accurate picture of waste generation containing heavy metals.

Key Words

Heavy metal, Designated wastes, Allbaro system, Statistics

권오철 Oh Chul Kwon , 박영규 Young Gyu Park

DOI:10.9786/kswm.2017.34.8.801

Abstract

Biogas is a gaseous mixture produced from the microbial digestion of organic materials in the absence of oxygen. Raw biogas, depending upon organic materials, digestion time and process conditions, contains about 45 ~ 75% methane, 30 ~ 50% carbon dioxide, 0.1% hydrogen sulfide gas, and a fractional percentage of water vapor. To achieve the standard composition of the biogas, treatment techniques like absorption or membrane separation are performed for the resourcing of biogas. In this paper, the experiments are performed using biogas produced in an environmental digestion facility for food waste. The membrane module was imported from overseas, its membrane process has achieved up to 98% of the methane and 99% of the carbon dioxide separated, and it has manufactured and stored pressurized carbon dioxide. The effects of the feed pressures on the separation of CO₂-CH₄ by the membrane are investigated. A chelate was utilized to purify the methane from the H₂S concentration of 0.1%.

Key Words

Biogas, Food waste, Methane, Carbon dioxide, Hydrogen sulfide

박종훈 Jong-hun Park , 강신영 Shin-young Kang , 김상현 Sang-hyoun Kim

DOI:10.9786/kswm.2017.34.8.813

Abstract

This study investigated the feasibility of odor removal using ultrasonic droplets of electrolyzed water. 91.65% of the injected electrons were converted to oxidizing agents including hypochlorous acid at HCl 2.2%, 3 V, and a retention time of 5 min. The size of the droplets generated by the ultrasound showed a distribution with D25=1.359 μm and D75=2.506 μm. The odor removal efficiency of the electrolyzed water droplets was over 90% for a composite odor composed of acetaldehyde, hydrogen sulfide, and ammonia, while that of tap water droplets was 50%. The electrolyzed water droplets were also effective in removing ammonia generated in full-scale organic waste treatment facilities.

Key Words

Organic waste odor, Odor removal, Electrolyzed water, Ultrasonic droplet generation

박세원 Se-won Park , 서용칠 Yong-chil Seo , 이장수 Jang-soo Lee , 양원석 Won-seok Yang , 이상엽 Sang-yeop Lee , 한건호 Gun-ho Han , 정연욱 Yeon-ouk Jeong , 구재회 Jae-hoi Gu , 오종혁 Jong-hyeog Oh

DOI:10.9786/kswm.2017.34.8.819

Abstract

Bottom ash char, which is released and collected from a solid refuse fuel (SRF) gasification pilot plant, has been used as a feed material for one more step of the gasification process. This char contains higher unburned materials than the bottom ash collected from incineration plants. This could have sufficient potential for application to gasification technology. The lab-scale gasification experimental process consists of a downdraft gasifier, a cyclone, a scrubber, and a filtering system for the analysis of syngas. To find the optimal conditions and to decrease loss on ignition, the air equivalent ratio (ER) was adjusted from 0.1 to 0.5. The results of this experiment showed that 0.2 ER was the optimal condition, with 32.41% of cold gas efficiency and 40.41% of carbon conversion ratio. However, compared to the general gasification process, this efficiency and conversion ratio still seem to be low since the feedstock was the leftovers of the gasification process with a lower amount of volatile carbonaceous components. Furthermore, with increasing ER, the loss on ignition of the bottom ash in this experiment decreases due to the enhancement of the oxidation reaction. On average, it decreased by up to about 20% compared to the feedstock.

Key Words

Bottom ash, Char, Gasification, Syngas, Loss on iginition

고영재 Youngjae Ko , 강준구 Jun-gu Kang , 유하녕 Ha-nyoung Yoo , 권영현 Young-hyun Kwon , 손지환 Ji-hwan Son , 전태완 Taw-wan Jeon , 신선경 Sun-kyoung Shin

DOI:10.9786/kswm.2017.34.8.826

Abstract

Insulation materials used for building save energy and can be classified into inorganic and organic materials. Organic insulation emits toxic gases in a fire and has lower water resistance. Inorganic insulation is heavy and has poorer thermal performance than that of organic material. This study evaluated the physical properties and fire resistance of lightweight inorganic insulation foaming material made of waste glass powder. The test results showed that the inorganic material performed well with low density and low thermal conductivity for an insulation material. Foam insulation material manufactured from glass powder was sufficient as a fire-resistant product.

Key Words

Energy recovery rate, Pyrolysis-melting facility, Incineration heat, Incineration facility, Waste heat

이원준 Weon Joon Lee

DOI:10.9786/kswm.2017.34.8.835

Abstract

The use of mechanical treatment (MT) for preparing solid refuse fuel (SRF) using municipal solid waste has been growing in Korea. One of the problems with using this treatment measure is the generation of residual waste from the MT, which will not be contained in the SRF. Most of this waste will be dumped into landfill instead of being used for the production of SRF. Much of the waste will be organic portions originating from food and biodegradable wastes. Consequently, the organic portion dumped into the landfill generates methane gas, which is a strong greenhouse gas. In this paper, the waste from MT was investigated directly at the MT facility located at Su-Do-Kwon landfill site to develop proper treatment measures to avoid disposing of the MT waste in landfill, which is prohibited in Germany and England.

Key Words

Mechanical treatment, Leftovers, SRF (Solid Refuse Fuel)

정용길 Yong-gil Chong , 박진규 Jin-kyu Park , 김란희 Ran-hui Kim , 이남훈 Nam-hoon Lee

DOI:10.9786/kswm.2017.34.8.844

Abstract

The objective of this research was to estimate the greenhouse gas (GHG) emission factors for food, paper, and wood wastes through methane (CH₄) flow analysis. The GHG emissions from a given amount of landfill waste depend on the carbon (C) flows in the waste: (1) carbon storage in landfills, (2) C in carbon dioxide (CO₂) and CH4 generated in anaerobic waste decomposition, (3) C in CO₂ and CH₄ emitted to the atmosphere through vertical gas wells, (4) C in CO₂ from CH₄ oxidation through cover soils, and (5) C in CH₄ emitted to the atmosphere through cover soils. This study reviews the literature on the ranges for DOC_f (the fraction of degradable organic carbon that can decompose) and OX (oxidation factor) values of food, paper, and wood, with a particular focus on the role of lignin. There is an inverse relationship between lignin and the DOC_f of paper and wood wastes. In this respect, the lignin content could be used as an abatement indicator for the DOC_f of paper and wood. The literature review shows that the average DOC_f values for food, paper, and wood were 0.72, 0.61, and 0.12, respectively. The country-specific DOC_f value for wood (0.44) is significantly higher than the ranges reported in the literature, which implies that the country-specific DOC_f for wood can overestimate GHG emissions compared to the DOC_f obtained from the literature. The estimated GHG emissions factors were 1,055 kg-CO₂e/ton-wet waste for food, 1,367 kg-CO₂e/ton-wet waste for paper, and 276 kg-CO₂e/ton-wet waste for wood. Sensitivity analysis results showed that the most influential parameters were MCF (CH₄ correction factor), DOC_f, and OX. In order to reduce GHG emissions from landfill in Korea, landfill sites currently in operation should be converted from anaerobic to semi-aerobic.

Key Words

Greenhouse gas, Emissions factor, Landfill, Municipal solid waste, Carbon flow

한소영 Soyoung Han , 최연석 Yeon-seok Choi , 최상규 Sang-kyu Choi , 김석준 Seock-joon Kim , 타우시프라만 Tawsif Rahman

DOI:10.9786/kswm.2017.34.8.853

Abstract

To produce palm kernel shell (PKS) biocrude oil, a bubbling fluidized bed pyrolyzer was used with different sample sizes and reaction temperatures. The PKS sample sizes used were 0.1 ~ 0.4 mm, 0.4 ~ 1.0 mm, and 1.0 ~ 2.0 mm and the reaction temperature were 465℃, 490℃, 530℃, 560℃, and 590℃. The yield of PKS biocrude oil increased with decreasing the sample size. The maximum yield of PKS biocrude oil was 47.31% at 560℃ with a PKS sample size of 0.1 ~ 0.4 mm. In addition, the maximum energy yield of PKS biocrude oil was 45.05% at 560℃ and size 0.1 ~ 0.4 mm. Among the characteristics of PKS biocrude oil, the high heating values are from 15.98 MJ/Kg to 20.29 MJ/Kg, the moisture content is from 20.14wt.% to 31.57wt.%, and the viscosity ranges from 0.0117 N s/㎡ to 0.0408 N s/㎡. In addition, proximate analyses and elemental analysis of PKS biocrude oil were conducted.

Key Words

Biocrude-oil, Palm kernel shell, Biomass pyrolysis, Bubbling fluidized bed (BFB)