박연진 Youn Jin Park , 신원식 Won Sik Shin , 최상준 Sang June Choi

DOI:

Abstract

The effects of chemical binders (ladle slag, ordinary portland cement (OPC), hydroxyapatite and calcium hydroxide) on the solidification/stabilization of heavy metals (Cd, Cu, Ni, Pb, Zn) in sewage sludge were evaluated by chemical leaching tests such as EDTA (ethylenediaminetetraacetic acid) extraction, TCLP (Toxicity Characteristic Leaching Procedure) and sequential extraction. The results of EDTA extraction showed that heavy metal concentrations in sewage sludge were highly reduced after solidification/stabilization with slag, cement or calcium hydroxide. However, EDTA interrupted solidification/stabilization of heavy metals by hydroxyapatite. The TCLP-extracted heavy metal concentrations in sewage sludge after solidification/stabilization with chemical amendments were highly reduced. However, Cu concentration in sewage sludge solidified/stabilized with slag, cement or calcium hydroxide increased because the pH of TCLP solution was higher than 7. Mixtures of sludge 1: slag 0.1: calcium hydroxide 0.05 (wt. ratio) showed the least leachability in batch TCLP and EDTA extraction. The results of sequential extraction, The Standard, Measurements and Testing programme of European Union (SM&T, formaly BCR) indicated that the distribution of heavy metals moved from exchangable and carbonate fractions to strongly bound organic material and sulfides fraction. It was found that maximum leachate concentrations of Ba, Cd, Cr and Pb from sewage sludge amended with ladle slag and calcium hydroxide were far below TCLP regulations.

Key Words

Solidification/Stabilization, Sewage sludge, Heavy metals, Chemical binders, Ladle slag, Ordinary Portland cement (OPC), Hydroxyapatite, Calcium hydroxide

윤상훈 Sang Hoon Yoon , 정숙경 Suk Kyeong Jung , 송형명 Hyung Myung Song , 위환 Whan Wi , 강영주 Yeong Ju Kang , 백계진 Ke Jin Paik , 문용운 Yong Un Moon , 이용운 Yong Un Lee

DOI:

Abstract

The purpose of this study was to investigate the sources and characteristics of city nonpoint pollutant and also provide the basic data for proper management plans of nonpoint pollutant by using the results to analyze heavy metals and organic matter from the major roadside sediment. Total 20 samples from the roadside sediment were collected in Gwangju City during April and August in 2010. The results of pH were ranged from 6.8 to 9.3, slight alkalinity generally. Average concentrations of heavy metals were 336.861 mg/kg for Zn, 98.377 mg/kg for Cu, 58.406 mg/kg for Pb, 32.153 mg/kg for Ni and 0.583 mg/kg for Cd. The case of Hg and As were similar to natural abundance. Average concentration of Ni, Cu and especially Zn increased during April and June which is called the yellow sand season, but decreased during July and August, which is called the rainy season. Average concentration of organic matter were 5782 mg/kg for CODcr, 82.72 mg/kg for T-N and 282.29 mg/kg for T-P. The correlation analysis among heavy metals, showed that the correlation between Cu and Cd was highest (0.75, P<0.01) and also there were significant correlations among Cu - Ni, Zn - Ni, Zn - Pb and Zn - T-P. In addition, geoaccumulation index indicated the Igeo-class of Cu was ``very strongly polluted``, Pb and Cd were ``strongly polluted``, Zn was ``Moderately/strongly``.

Key Words

Roadside sediment, Nonpoint pollutant, Geoaccumulation index, Igeo-class

김영훈 Young Hun Kim , 송태협 Tae Hyeob Song , 이세현 Sea Hyun Lee

DOI:

Abstract

One of the basic physical properties of the hardened cement paste, the rigidity, is deteriorated during concrete matrix forming, depending on the replacement rate of the crushed stone powder, and due to drying shrinkage. Therefore, the concrete containing crushed stone powder has been limitedly used as non-structural construction material. To improve these disadvantages, a hydrothermal reaction employing method can be considered. High-temperature and high-pressure water is involved in the hydrothermal reaction in the mixing with specific materials. The rigidity improving mechanism is related to the synthesis of calcium silicate. The calcium silicate is produced through reaction between calcium compounds and the silicic acid. Various kinds of calcium silicate can be produced depending on the CaO/SiO2 mole ratio, the temperature of the hydrothermal synthesis, the pressure, and the reaction time. The product of the synthesis mechanism, tobermorite crystal, plays a pivotal role for the rigidity reinforcement. The crushed stone powder, analyzed in this study, contains 50 to 60% of SiO2 and 10 to 20% AlO2. The composite rate is appropriate to create the tobermorite crystal through formation of hardened cement matrix under the hydrothermal synthetic conditions and with the CaO in the cement. Moreover, further reinforcement was promoted using the property of material under the identical density through promoting the formation of tobermorite crystal.

Key Words

Crushed stone powder, Cement, Hardened cement matrix, Hydro thermal reaction

김홍석 Hong Seok Kim , 이태진 Tae Jin Lee

DOI:

Abstract

The largest problem of domestic anaerobic digestion was low digestion efficiency. The cause of the problem would be low organic matters input, low mixing efficiency and refractory sludge etc.. In this study, in order to solve these sludge problems, ozone solubilization was used. Results of this study, SCODcr concentration was reported to have increased average 355.5% (100.7 to 680.0%) by ozone solubilization. In addition, the sludge solubilization efficiency was investigated to average 77.2 (51.8 to 96.0) %, and SCODcr/TCODcr ratio of digested sludge (before solubilization) was investigated to average 0.02 (0.01 to 0.04); and SCODcr/TCODcr ratio of solubilized sludge (after solubilization) was investigated to average 0.19 (0.09 to 0.70). Biochemical methane potential (BMP) results showed that microbial activity was decreased by the ozone solubilization and methane generation rate (reaction rate k) was decreased to 3.02-fold. However, this study`s results showed that methane production was increased to 1.52-fold and the methane generation rate (k) was improved to 1.44-fold in mixed sludge (mixing of digested and solubilized sludge) than only the digested sludge.

Key Words

Anaerobic digestion, Ozone, Solubilization, BMP test

이상혁 Sang Hyouck Lee , 박성근 Sung Geun Park , 이병인 Pyong In Yi

DOI:

Abstract

Using Bio Jet Reactor (BJR) to remove the high concentration wastewater generated by the solution separated from food waste, the results got from a pilot test are summarized as follows. 1. The characteristics of food wastewater was 4,010~8,640 mg/L for BOD5, 9,010~25,060 mg/L for CODCr, 2,810~5,160 mg/L for CODMn, 3,150~5,320 mg/L for T-N, 1,228~4,395 mg/L for NH4-N, 10.5~50.0 mg/L for T-P and 350~570 mg/L for SS. 2. The characteristics of the food wastewater that was treated by BJR was 78~186 mg/L for BOD5, 35~360 mg/L for CODCr, and 70~118 mg/L for CODMn, 26.5~650 mg/L for T-N, 0.3~14.5 mg/L for NH4-N, 3.8~6.9 mg/L for T-P and 40~65 mg/L for SS. 3. The removal efficiency for BOD and CODCr was about 98.3% and 98.5% respectively. and the removal efficiency for T-N and NH4-N was about 97.7% and 99.8% respectively. 4. When the quantity of the wastewater or the pollution load was increased in the treatment plant using a conventional activated sludge process, the BJR was found as the most efficient treatment method that is not restricted by the size of the plant. 5. The optimum operation condition to remove the high concentration wastewater was 0.6 kg/m3·d for TKN volumetric loading, 0.12 kgTKN/kgSS·d for TKN-sludge loading, 20~35oC for temperature, and 300% for Internal recycle of First Anoxic Tank.

Key Words

Food waste, Food wastewater, High concentration nitrogen removal, Treatability test, Bio Jet Reactor (BJR), Optimum operation condition

김득모 Deuck Mo Kim , 이화영 Hwa Young Lee , 박찬규 Chan Kyu Park , 이승훈 Seung Hoon Lee , 문경주 Kyoung Ju Mun , 소양섭 Yang Seob Soh

DOI:

Abstract

This paper focused on investigation of anti-acid properties of hardened geo-polymer, mainly involving observation of changes in mass, which resulted from corrosion by acid and also, compressive strengths of different geo-polymer. Analytical techniques including SEM, EDS (Energy Dispersive x-ray Spectroscopy), MIP (Mercury Intrusion Porosimetry) were performed in order to investigate corrosion processes induced by different types of acid. The results showed that the mass of hardened geopolymer decreased in hydrochloric acid while it increased in sulfuric acid.

Key Words

Geo polymer, Alkali activate slag, Chemical resistnace, Pore Analysis, SEM

석종혁 Jong Hyuk Seok , 최홍복 Hong Bok Choi

DOI:

Abstract

Mixing characteristics in a plug-flow multi-stage (PFMS) anaerobic reactor and effects of shock loads in food waste treatment were examined In this study. Mixing in the PFMS reactor showed the typical characteristics of multi-stage reactor and was more effective than in a general type of longitudinal reactor mainly due to gas eruption from the gas hold-up spaces of columns. At steady state with 30 d of HRT, pH and COD were maintained stable, but pH and COD removal efficiency were quickly decreased under shock loads resulting from the unstability of the reactors under the shock loads. At steady states, acetic (HAc) and propionic (HPr) acids, were less than 4,000 mg/L for HAc and 2,000mg/L for HPr, respectively. However, HAc was increased up to 12,616 mg/L and HPr 17,569 mg/L when shock loads were applied. Gas production was ranged in 0.62~0.64 Nm3/kg VS removed and 1.6~1.7 Nm3/m3 digester-d. Methane production rates were rapidly decreased at shock loads, and remained unstable even after being returned to normal operating condition, indicating that the adverse effect of shock loads would not be short but lasted enough to lead system failure, and thus should be avoided. In particular, it was revealed that longer input interval at the same organic loads showed more detrimental on the reactor performance. Unlike TS, pH, organic fatty acids, organic removal efficiency and gas production rate were proven to be useful as indicators of shock loads.

Key Words

Food waste, Shock Loads, Plug-flow multi-stage reactor, Anaerobic treatment, Biogas

박송인 Song In Park , 나숙현 Suk Hyun Na , 강창민 Chang Min Kang , 정선용 Seon Yong Chung , Saido Kstsuhiko , Sato Hideto

DOI:

Abstract

Recently, the huge quantity of plastic waste floating on the world`s oceans was swept Korea ashore. Bisphenol A (BPA) and styrene oligomer (styrene monomer, styrene dimer and styrene trimers) eluted from floating plastic waste become instigators of disrupted endocrine function and related human health problems. Therefore, to investigate the contamination degree of the coastal areas by the drifting polystyrene materials, we perfomed the field investigation of Korea coasts - East Sea, South Sea, West Sea, and Jeju Island by using GC/MS. In East Sea, concentration of BPA was detected in 0.96 to 23.8 ng/mL range, and BPA values of West Sea and South Sea were detected in 2.20 to 4.95 ng/mL and from 2.16 to 6.11 ng/mL range, respectively. Also, in all of Korean coastal area, Styrene Monomer (SM) was detected in lower concentration and Styrene Trimer (ST) showed relatively higher concentration. Futhermore, concentraion of styrene oligomer (SM, SD, and ST) showed the highest value at coast of Jeju Island among them. These results indicate that plastic marine debris is the cause of the new marine environmental hormonal pollution in Korea coastal areas.

Key Words

Bisphenol A, Contamination investigation, Korea coastal areal, Polystyrene, Styrene oligomer

최재서 Jae Seo Choi , 이종철 Jong Chol Lee , 최성한 Sung Han Choi , 김선환 Sun Hwan Kim

DOI:

Abstract

Solid propellant for rocket motor consists of an oxidizer and aluminum powder cured in a polymeric binder. The oxidizer, ammonium perchlorate (AP) can be readily removed by suitable solvents leaving a residue consisting of aluminum and polymer. Since AP is highly soluble in water, water-washout process was proved to be safe and economical way to remove propellant from the motors. High pressure water-jet was used to remove propellant loaded in rocked motors. The removed propellant was then shredded, macerated with water and filtered to separate non-soluble materials such additives as binder and aluminum used as fuel. After evaporating water from the AP solution, AP crystal was obtained for recycle. Using this process, we safely disposed unserviceable rocket motors and recovered AP with purity above 99%.

Key Words

Solid rocket motor, Ammonium perchlorate, Rocket motor demilitarization, AP recovery

이병선 Byung Sun Lee , 남상철 Sang Chul Nam , 남궁완 Wan Nam Koong

DOI:

Abstract

In this study, the single stage anaerobic co-biogasification (SSACB) was performed to convert dehydrated liquids to bio-gas (CH4) after Grinded food waste (GFW) and primary sewage sludge (PSS) was blended and dehydrated, together nuder mesophilic condition (35oC), and 5,000 ppmCaCO3, various foodwaste mixing ratio-MR1 (GFW: PSS mixing ratio, 1: 1 volume base), MR3 (GFW: PSS mixing ratio, 1: 3 volume base) and MR5 (GFW: PSS mixing ratio, 1: 5 volume base) for Bio-gasification. At MR5 (the lowest food waste mixing ratio), It showed the highest TS and VS reduction of 47.4% and 61.7% individually, Percentage of Acidified COD was 44.2%, The optimal Experimental cumulative methane yield (ECMY) and Experimental bio-energy production (EBEP) were 0.18 L CH4/g VSfed and 1,552 cal/g VSfed for 31 days. In the case of MR1 and MR3, Food waste was broken down and solubilized too faster, which produced excessive VFA. It caused buffering capacity to be declined and reduced pH up to about 5.8 and 6.3 respectively. It was considered that methanogenic bacteria was inhibited from harmoniously converting VFA to CH4, VFA built up continuously in each reactor. As result of this study, It is important factor that mixing ratio of more easily biodegradable organic waste like food waste among various organic materials should be controlled to effectively operate SSACB.

Key Words

Anaerobic digestion, Co-Biogasification, Food waste, Sludge, Bio-gas

정봉진 Bong Jin Jung

DOI:

Abstract

Viscosities of melting samples as a function of temperature were measured using rotating bob viscometer in an inert atmosphere to find the optimum operating temperature in a melting system for the treatment of various samples including coal ashes, sewage sludge ashes, MSW incineration bottom and fly ashes. Viscosities of the above samples were closely related with their ash compositions. The alkali or alkaline earth content was higher, the viscosity was lower at a given temperature. Temperature ranges corresponding 8 Ns/m2 which gives sufficient fluidity to allow free flow of slag without difficulty were higher at the high-rank coal and sewage sludge ash slags than the low-rank coal and MSW incineration bottom ash and fly ash slags. The viscosity results were also compared with Base/Acid Ratio, Basicity, Lignite Factor and Silica Ratio based on their ash compositions to describe the slagging propensity of solid wastes and coal ashes in the melting system.

Key Words

Solid waste ash, Coal ash, Viscosity of slag, Base/Acid Ratio, Lignite factor, Silica ratio

김은영 Eun Young Kim , 최상원 Sang Won Choi , 박지현 Ji Hyun Park , Viktor Kim , Li Yujia

DOI:

Abstract

We investigated the effect of hydrochloric acid and particle size of the slag from ferronickel manufacturing process on the extraction of magnesium, iron and silica components. The major chemical composition of the slag sample was as follows: 54.05% SiO2, 34.33% MgO, 5.51% Fe2O3 and the main structure components were forsterite and fayalite of olivine group. The highest extraction of Mg and Fe, correspondingly 81.38% and 80.55%, was provided by leaching the slag particles of 200 μm with 6 M HCl. The main structure of small particles (under 350 μm) was mainly composed of forsterite and the big particles was composed of fayalite, as identified by XRD analysis. As the particle size was decreased from 1,000 μm to 53 μm, the extraction ratio of magnesium was increased from 51.13 to 87.52% and iron was increased from 56.68 to 88.70%. The extraction ratio of magnesium and iron was also increased with increasing HCl concentration.

Key Words

Ferronickel, Slag, Extraction, Magnesium, Particle size

이승희 Seung Whee Rhee

DOI:

Abstract

Control characteristics on VOC reaction with ceramic supports manufactured by the mixture of spent foundry sand (SFS) and sewage sludge (SS) were estimated. Formaldehyde (HCHO) among VOCs is used in the experiment of column test. Types of ceramic supports used in the experiment are SFS/loess/SS/additive support, SFS/loess support, SFS/loess/SS support, and loess support. As increased the residence time (dimensionless) in the column test, HCHO concentration is dramatically decreased until the residence time of 1 and almost constant after the residence time of 3. Since reaction rate constant of HCHO reaction is exponentially decreased with increasing input flow rate, the control of HCHO is mainly occurred at the beginning stage of reaction. As increased input flow rate, breakthrough time is dramatically decreased until flow rate of 100 ml/min and dereased slowly above the flow rate of 100 ml/min. The removal efficiency of HCHO in the column test is increased from 88% at the residence time of 1 to 98% at the residence time of 10. The control effect of HCHO with types of ceramic support is followed by the order of SFS/loess support

Key Words

Spent foundry sand, Sewage sludge, Ceramic support, VOC, HCHO, Control reaction

홍선화 Sun Hwa Hong , 신기철 Ki Chul Shin , 이은영 Eun Young Lee

DOI:

Abstract

The role of plant growth-promoting bacteria (PGPB) in the bioremediation of BTEX contaminated environment is important in overcoming its limitations for field application. A plant growth-promoting bacterium, Pseudomonas putida AY-10, was isolated from the rhizosphere of wastewater treatment reed. This isolate has shown capacities for indole acetic acid production (10.72 mg/L of IAA accumulation during 5 days) and ACC deaminase (Absorbance value: 0.49±0.01 72) by 72 hours incubation. In addition, although P. putida AY-10 was incubated in BTEX-BH medium, it could degrade pure B, T, E, and X without any lag period. The P. putida AY-10 was able to completely degrade BTE after 15 h, almost 100% and X after 50 hour incubation under aerobic condition. Measured BTEX removal efficiencies by various means were±10% by natural attenuation, 70% in benzene, toluene, and o-xylene by the combination of Pteridium aquilinum and Pseudomonas putida AY-10. These results indicate that rhizoremediation using both Pteridium aquilinum and Pseudomonas putida AY-10 is a promising strategy for enhancing remediation efficiency of BTEX-contaminated soils.

Key Words

Biodegradation, BTEX, DGGE, Rhizosphere, Pseudomonas putida, Wastewater treatment