이주광 , 이승목 , 윤이용 Ju Goang Lee , Seung Mok Lee , Yi Yong Yoon

DOI: Vol.12(No.3) 237-243, 1996

A survey of Volatile Organic Compounds(VOCs) was conducted in the Kangnung City raw water, treated water and groundwater from Mar. 1994 to Dec. 1994. Four VOCs. 1,1,1- trichloroethane, carbon tetrachloride, trichloroethylene and tetrachloroethylene, were detected below detection limit level. Among those, 1,1,1-trichloroethane, carbon tetrachloride and trichloroethylene were detected at trace and frequently. Trichloroethylene was contaminated in the highest level among detected four VOCs. The mean concentrations of trichloroethylene were 1.15㎍/ℓ of the raw water, 3.30㎍/ℓ of the treated water and 0.47㎍/ℓ of the groundwater. respectively. The concentration levels of the VOCs from the raw water and the treated water were increased from winter to summer, while this trend cannot be found in groundwater.

염혜정 , 강구영 , 박갑성 Hye Jung Yeum , Gu Young Kang , Kap Song Park

DOI: Vol.12(No.3) 245-248, 1996

Bioremediation of PAHs(Polynuclear Aromatic Hydrocarbons) contaminated soils was evaluated using cooxidation process. Bioremediation potential for hazardous PAHs constituents was substantial in the presence of growth substrate phenanthrene. Mean half-life values of pyrene and benz(a)anthracene with phenanthrene substrate were 27.7% and 33.3%, respectively, of the half lives for each pyrene and benz(a)anthracene without phenanthrene. Soil enzyme activities were significantly enhanced by the addition of phenanthrene substrate through catalyzing oxidation of pyrene and benz(a)anthracene.

김영주 Young Ju Kim

DOI: Vol.12(No.3) 249-255, 1996

The wet oxidation catalyzed by UV -irradiation for the treatment of waste water or liquid waste needs hydrogen peroxide as an oxidizing agent. Hydrogen peroxide as a metastable substances is subjected to a gradual decomposition. In the process, shortliving and highly reactive hydroxyl radicals are formed. The decomposition can be significantly accerated by use of an appropriate catalyist, such as the ultraviolet radiation in the wavelength range between 190 and 300nm. In this study for the treatment of wastewater with hydrogen peroxide and UV-irradiation a falling film reactor was used. The waste water, which contains a high concentrations of organic compounds and AOX, was from a chemical-phamaceutical industry. By using a high pressure mercury lamp without dosage of hydrogen peroxide as well as with dosage of hydrogen peroxide could be AOX and TOC good eliminated. With dosage of hydrogen peroxide l0㎖/ℓ AOX could be eliminated from a concentration of 25㎎/ℓ to 0.6㎎/ℓ and anly using a high pressure mercury lamp without dosage of hydrogen peroxide could be AOX eliminated to 1.2㎎/ℓ. The effect of AOX elimination was higer at high controled pH condition of 10 than original pH condition of 6.3.

최의소 , 이경수 Eui So Choi , Kyeong Su Lee

DOI: Vol.12(No.3) 257-265, 1996

Nitrogen removal from sanitary landfill leachate representing average COD of 3000㎎/ℓ and TKN of 1200㎎/ℓ intensively studied with SBR operated with 5d HRT(30d SRT) with 24hr cycle time at 20℃. Addition of phosphorus as nutrient was necessary, but pretreatments like ammonium stripping, and electrolysis did not improve the overall nitrogen removal since the elevated pH showed increased inhibition to nitrifiers. NO₂N accumulation was typical phenomenon throughout the operating periods and this inhibited the conversion to NO₂N. However, nitrogen removal efficiencies were varied with COD/TKN ratio; higher nitrogen removal with higher ratio and lower removal with lower ratio. COD/TKN$gt; 4.6 exhibited more than 93% nitrogen removal efficiencies. Addition of acetate as external carbon source could improve nitrogen removal efficiencies. Acetate requirements as COD were respectively 1.49㎎ COD/㎎ NO₂N, and 2.01㎎ COD/㎎ NO₄ N. The remained NO₂N in effluent increased COD, and a complete removal of NO₂N would reduce the COD concentrations in the effluent. Kinetic evaluation would suggest the denitrification from NO₂N could reduce the aeration and anoxic times to 30% and external carbon source to 26% in comparison to those from NO₃N.

민왕기 , 고영송 , 남상호 Wang Gi Min , Young Song Ko , Sang Ho Nam

DOI: Vol.12(No.3) 267-275, 1996

This study is to investigate the characteristics of changes in Humic acid before and after ozonation. The results were compared with such terms as COD_(Cr),(K₂Cr₂O_7), COD_(Mn)(KMnO₄), UV_(254)(Ultra-violet absorbance, λ 254), BDOC and yield coefficient after ozonation of Humic acid were determined by the means of Heterotrophic plate count(HPC) method and Total Organic Carbon(TOC) analyzer. The percentage of BDOC in DOC of Humic acid before the ozonatiott was 4%, which was relatively low. The yield coefficient of HPC per Humic acid was 3.8 × 10^7 CFU/㎎ which is equivalent to 2.3 × 10^9 CFU/㎎ of BDOC. UV_(254) was more sensitively decreased than CUD_(Cr) and COD_(Mn). From this fact, it was inferred that the characteristics of Humic acid was changed by the different levels of ozone oxidation. As a result of ozonation. BDOC was increased. But at the maximum BDOC level, the concentration of ozone per ㎎ DOC was l㎎ to 1.5㎎ and 1.9㎎ at a ozone concentration of 2㎎/ℓ in the solution. The yield coefficient of BDOC was also increased.

조영관 , 배석진 , 백순기 , 이정전 Young Gwan Cho , Seok Jin Bae , Soon Ki Baik , Jung Jun Lee

DOI: Vol.12(No.3) 277-284, 1996

When wild growing plants such as Alopecurus aegualu var. amurensis were submerged in water for experiment, the conductivity and color of the water increased to a maximum 67 times that of raw water on the edged of Dongbok reservoir. In case of withered matters of Setaria viridis, the variation of color vas small, but when withered matters of Persicaria lapathafolia - which is used for dye materials - were submerged, the increasing rate of water color was very high. The variation of concentration of phosphorus and nitrogen in growing plants such as A. aegualis var, amurensis was 4∼37times and 2.5∼10times higher than that of withered plants(S. viridis and P. lapathafolia). As for treatment method. when ashes of A. aegualis var. amurensis were submerged in water, the concentration of total nitrogen(TN) and total phosphorus(TP) decreased more than that of non-treated. On the contrary, in case of withered matter of Persicaris lapathafolia, when ashes were submerged in water, the concentration of TN and TP increased more than that of the nontreated. Total nitrogen amount from the total plant biomass in the Dongbok reservoir was 12,821㎏ and total phosphorus amount was 1,141㎏. From among them, the amount of TN and TP in Persicaria lapathafolia was larger than that of any other dominant species.

염익태 , 안규홍 Ick Tae Yeom , Kyu Hong Ahn

DOI: Vol.12(No.3) 285-295, 1996

Dissolution of PAHs from a mixture of soil and multi-components coal tar was studied in batch experiments. Equilibrium aspects of the release of individual components into water were evaluated by washing the soil/tar mixture with deionized water. Solubilities of PAHs in the mixture were much less than their intrinsic aqueous solubilities. Only a small fraction ($lt;0.1%) of soil-bound PAHs could be dissolved when 100g soil was washed with 1L water. Equilibrium partitioning of PAHs between soil/tar and water could be described by Raoult`s law assuming the tar residues in the soil behave ideally. To investigate kinetic aspects of PAH release from the soil/tar, Tenax - TA, a polymeric adsorbent was used. Tenax adsorb aqueous PAHs completely from solution and thus maximize their mass transfer at the soil/tar - water interface. With Tenax in water, most constituent PAHs failed to attain equilibrium, indicating the release of PAHs from soil/tar mixture is a slow, rate-limiting process. To elucidate the rate- limiting process, both interfacial mass transfer(film diffusion) and matrix diffusion models were tested to fit the observed data. Model analysis revealed the diffusion of PAH through the organic matrix of soil/tar is most likely the process responsible for the slow release of PAHs.

최상일 , 류두현 , 김광수 , 장민 Sang Il Choi , Doo Hyun Ryoo , Kwang Soo Kim , Min Jang

DOI: Vol.12(No.3) 297-304, 1996

To improve the efficiency of recovering polycyclic aromatic hydrocarbons(PAHs) from soil and aquifer, the solubilization of naphthalene was studied for the commercial nonionic chemical surfactants and a microbial surfactant : polyoxyethylene alkyl ester, polyoxyethylene acyl sorbitan. and sophorolipid. The critical micelle concentration(CMC), molar solubility ratio (MSR), and partition coefficient(K◎) were measured or calculated for each surfactant. Effect of surfactant structure on solubilization was compared. MSR and K◎ were generally increased as hydrophile-liptrophile balance(HLB) of a surfactant was decreased. Surfactants having HLB of 8 and 13 were recommended for ex-situ soil washing and in-situ soil flushing. respectively. Considering physical characteristics such as CMC, MSR, K◎ and HLB, sophorolipid was the most desirable surfactant for ex-situ soil washing and in-situ soil flushing of polycyclic aromatic hydrocarbons from the contaminated soil.

이재영 , 최상일 Jai Young Lee , Sang Il Choi

DOI: Vol.12(No.3) 305-311, 1996

The cover system at municipal and hazardous waste landfills is expected fo perform the following functions: 1) promote surface runoff, 2) the minimum of impede infiltration, and 3) provide a buffer from surface exposure of the waste. However, in spite of cover systems in the landfill is very important, there are not much researches of the landfill cover liner systems. Generally, one of the primary mechanisims of landfill cover liner failure in cold regions is cracking due to the freeze/thaw phenomena. Once the cover liner cracks, performance of these functions ins compromised. Also, The degradation of cover liner systems causes to increase the leachate generation and makes one of the major reason in groundwater contamination. In this investigation, the research performed cover liner behavior in cold weather and actually, allowing inclusion of the field cover systems, clay and layered material profiles. This paper provides the description of testing cover systems, experimental results and a discussion of results of the simulation. The experimental results include rainfall, moisture contents in the clay, leakage data and water balance for each design. The results also indicate the depth of frost penetration for four designs, and a design which consists of soil drainage has superior leakage performance.

박철휘 , 정태학 Chul Hwi Park , Tai Hak Chung

DOI: Vol.12(No.3) 313-319, 1996

Operational characteristics of the UASB Process were studied using a l㎥ pilot plant treating wastewater from a starch manufacturing industry. The reactor was operated with a HRT of 8 hours and the temperature was maintained at 35, 30, 25, and 20℃ for a significant period. COD loading rate varied from 7 to 14㎏/㎥-day as a result of fluctuating influent COD concentration. Both COD removal and the gas production decreased gradually as the temperature decreased. However, reduction of the treatment efficiency at low temperatures was not severe at all. Gas production decreased from 0.256㎥ per ㎏ COD removed to 0.191 as the temperature droped from 35℃ to 20℃. VS reduction efficiency also decreased gradually as the temperature decreased. Although slight increase of the volatile fatty acid was observed at low temperatures, stability of operation based upon pH, alkalinity and volatile fatty acid was maintained at all temperatures. It is believed that stable operation at low temperatures is possible due mainly to accumulation of active sludge granules in the reactor. The sludge granules, 0.7 to 1.2㎜ in size, were mostly composed of rod shaped and filamentous microorganisms with a number of pores.