A milky gray scum was observed at some water area of the lake Daecheong in the summer of 1997 and 1998. To identify a causing organism of scum and affecting factors, we observed the scum material by a phase contrast microscope and surveyed the phsico-chemical water quality during the outbreak of scum. The scum was found out to be clogging cysts of amoeboid protozoan, Asterocaelum sp.(Protozoea Sarcodina Aconchulinida), grazer of filamentous cyanobacteria, Anabaena genus. The protozoan scum appeared during Anabaena bloom period, which continued for a while. This protozoan was presumed acting as a regulator of Anabaena bloom in the lake Daecheong during the summer season. Moreover this is the first report on Asterocaelum sp. a grazing filamentous cyanobacteria occurred in Korean freshwater.

To develop the removal technique of algal bloom the efficiencies of algal flocculation/ autoflotation by the kinds of coagulant and oversaturated oxygen concentration were investigated. The summarized results are as follow. 1. In the algae flocculation test with alum[$Al_2(SO_4)_3{\cdot}18H_2O$], optimum pH was 5.5 and, with chitosan optimum pH was 7.0. 2. Chitosan which was natural polymer showed the 5~10 times higher algal biomass flocculation efficiency than alum in the condition of same algal concentration. 3. For the each coagulant, the higher ${\Delta}DO$(oversaturated dissolved oxygen concentration - saturated dissolved oxygen) was, the faster the rising velocity of the algal floc was. 4. In the condition of about 4mg/L ${\Delta}DO$, the rising velocity of chitosan is about 2 times higher than that of alum, and chitosan formed the stronger algal floc.

The water treatment by ozone was performed to remove VOC and organic substances in the multistage ozone contactor. This paper is secondary paper about the theme of ozone treatment since the first paper (Kor. Sanitary J., 15, 1(2000)) publicized, it was compared experimental results with theoretical those which were derived from the mathematical model associated with chemical reactions and mass transfer. Basic designing factors were determined as an optimal conditions for the removal rate of VOCs as follows: ozone input concentration in the contactor was 2mg/L, ozone contact time was 7 min and number of contactor was three-layered.

1%, 2%, 10%, 및 20%의 가교도를 갖는 클로로메틸화된 1,4-divinyl benzene에 1-aza-15-crown-5 거대고리 ligand를 치환반응으로 결합시키고, 이들 수지로부터 흡착에 미치는 pH, 시간, 수지의 가교도 그리고 용매의 유전상수 크기에 따른 흡착특성을 조사하였다. 금속이온들은 pH 4 이상에서 우라늄과 칼슘 이온들은 루테튬 이온보다 큰 흡착률을 보였으며, 금속이온들의 흡착 평형시간은 약 2 시간이었다. 한편, ethanol 매질에서의 흡착선택성은 $UO_2^{2+}>Ca^{2}>Lu^{3+}$ 이었고, 흡착력은 1%, 2%, 10%, 20%의 가교도 순 이었으며, 용매의 유전상수(물 : 78.54, 메탄올 : 32.63, 에탄올 : 24.30) 크기에 반비례하였다. 컬럼에서 1%의 가교도를 가진 수지와 금속이온들을 흡착시킨 후 용리액으로 pH2.5 $HNO_3$을 사용하여 각각 분리할 수 있었다.

In the screening of phenol-degrading bacteria, a strain showing good growth in media containing phenol was isolated by using enrichment culture from various sample and identified as genus Klebsiella pneumoniae. The optimal temperature and pH for cell growth of Klebsiella pneumoniae was $35^{\circ}C$ and 8.0, respectively. When phenol was added to the minimal media as a sole source of carbon and energy, the concentration of maximum and optimum for cell growth was 1,200ppm and 1,000ppm, respectively. It was observed that Klebsiella pneumoniae was able to degrade 98% of phenol (1,000ppm) after 40hr in culture. The isolated could utilize various kinds of aromatic compounds and showed good growth in presence of phenol, m-cresol and 3-methyl catechol.

The purpose of this study was conducted to indentified the fixing quality of $CO_2$, the most important greenhouse effect gas, by microalgae Chlorella ellipsoidea in batch test apparatus. The glass flask of $1.4{\ell}$ culture media which was saturated with 99.99% pure $CO_2$ gas was setted water bath of $25^{\circ}C$, 5000Lux, and seeded 100$m\ell$ algae liquid. We checked the change of inorganic carbon concentration and algae population with time in culture media. The result were next: the growth of algae population relied on aquatic IC(inorganic carbon) concentration. And the pH was increased with decrease of IC concentration. The growth of algae population had positive correalation with $CO_2$ concentration, and the coefficient of correlation was 0.982. The specific growth rate($\mu$) of Chlorella ellipsoidea was 1.104/d, the maximum specific growth $rate({\mu}_{max}$) of 9.21/d, and helf velocity constant($K_s$) of $259mg/{\ell}$ by Monod equation.

Korea has been free of malaria since the mid-1970s. Since the first malaria case was reported in 1993, the incidence of indigenous malaria has increased yearly, In this study, we planned to understand of malaria outbreak in the northern part of kyonggido. The subjects were a civilians except korean soldiers in the northern part of Kyonggido and the number of civilian malaria cases was 254 in 1997, 677 in 1998, 772 in 1999. The collected rates of Anopheles sinenis in 11 county from May to October were 10.1% to 85.1% and the monthly collected rates at June was highest. The incidence of malaria antibody according to the county was 5.4% in Paju-shi Tanhyun-myun 4.9% in Kapyong-gun Ha-myun, 3.0% in Yonchon-gun Yonchon-eup. etc. At the result of relationship between civilian cases and No. of A. sinenis, envionmental factor were showed high association.

We studied the adsorption characteristics on the treatment process of heavy metal wastewater by using cuttle fish bones powder. When adding the 0.25% cuttle fish born powder in the heavy metal solution, $Fe^{3+}$ and $Pb^{2+}$ were high removed than other heavy metals as above 95%. In the solution which was adjusted to pH 5, 7 and 9, there was not observed the difference thing on the heavy metal removal rate. At test using plating wastewater treatment, adding 1%, 1.5% and 2% of the cuttle fish born powder, the heavy metal removal rate were as follows; Zn 12.5 - 37.5%, Mn 18.0 - 62.2%, Cd 36.8 -93.0%, Cu 51.4 - 97.4%, Cr 70.8 - 99.1%, Fe 87.2 - 99.3% and Pb 92.8 - 99.9%. When adding the 0.15% cuttle fish born powder and mixing for 20 minutes, the solution was happened the adsorption equability. Applied this results to the Freundlich＇s iso-thermal equation, we found the cuttle fish born＇s probability as a good adsorbent.

This study was investigated to the recovery of alumina from the first calcined waste pottery using alkaline sintering. This study was based on calcination result of a commercial ${\alpha}-Al2_O_3$ with NaOH powder. $NaAlO_2$ was formed by calcination of ${\alpha}-Al_2O_3$ with NaOH and conversion of $NaAlO_2$ from ${\alpha}-Al_2O_3$ was 91.4% at calcination condition ; weight ritio of $NaOH/{\alpha}-Al2_O_3$ 1.5, $800^{\circ}C$, and 90min. The first calcined waste porrery from the manufacturing Procedure of H Ltd. was grinded to 170/270mesh by a ball mill and calcined over $500^{\circ}C$ with NaOH powder. The calcined sample was dissolved in $25^{\circ}C$ water and sodiumaluminosilicate solid was formed. After filtration, the contained aluminum was leached out by dissolving sodiumaluminosilicate solid in 1N HCl. We estimated the efficiency of Al extraction from waste pottery by ICP analysis and NaOH was added to the filtrate and then aluminum compound was precipitated with $Al(OH)_3$ and recovered. The investigation was carried out with the variables ; the calcination temperature($500-900^{\circ}C$), the calcination time(30~90min), and the weight ratio of NaOH/waste pottery(0.5~1.5). The treatment efficiency of the waste pottery and the recovery of Al as 97.9%, 91.9% were obtained under the optimum conditions as followed ; the weight ratio of NaOH/waste pottery was 1.5 and the calcination conditions were $900^{\circ}C$ and 60min.

폐수거품은 전 세계의 폐수처리장에서 악취생산과 BOD의 증가 및 부유고형물의 원인과 같은 수많은 문제들을 야기시킨다. Actinomycetes가 폐수거품에 존재하는 주요 미 생물군으로 알려져있다. Hexadecane은 폐수, 토양, 바닷물과 같은 자연환경에서 오염물질로 고려되는 복잡한 기름 성분의 대표적인 구성성분이다. Hexadecane은 폐수로부터 얻어진 폐수거품에 의한 분해가능성을 평가하기 위한 대표적인 모델 화합물로서 사용되었다. Gas chromatography (GC)/mass (MS)가 시료중에 있는 hexadecane의 분석을 위해 사용되었다. 본 연구를 통해서, hexadecane은 폐수거품에 의해 분해될 수 있는 것으로 사료된다. 멸균시킨 폐수거품시료를 포함하고 있는 control시료에서, hexadecane은 거의 분해되지 않았다. 반면에, 같은 방법에 의해 멸균되지 않은 폐수시료에서, hexadecane은 급속히 분해되었다. 덧붙여서, 농축폐수거품이 들어있는 시료는 3주 동안 건조된 폐수거품의 시료보다 hexadecane을 분해하는 데 더욱 효과가 높았다. 그러나, 3주 후에는 농축폐수거품의 시료에 남아있는 hexadecane의 농도는 건조된 폐수거품시료의 농도와 유사하였다. 요약컨대, 농축된 폐수거품시료와 건조된 폐수거품시료는 control시료와 비교했을 때, hexadecane의 급속한 분해를 보여주었다. 그러므로 본 연구의 실험결과를 통해서 건조된 폐수거품시료가 hexadecane을 비롯한 다른 chemical들로 오염된 장소를 정화하는 데 실제적으로 적용될 수 있을 것으로 사료된다.

클로로메틸화된 스틸렌, 1,4-디비닐벤젠과 동공의 크기를 달리한 여러 가지 거대고리 화합물을 개시제로 하여 공중합법에 의하여 1%, 2%, 10% 및 20%의 가교도를 가진 새로운 이온 교환수지를 합성하였다. 그리고 이들 수지에 대한 우라늄(VI), 니켈(II) 및 네오듐(III) 금속에 대한 흡착특성을 검토하였다. 이 수지들은 강산, 강염기 및 열에 대해서 안정하였으며, pH 4.0 이상에서는 $UO_2^{2+}$ 이온에 대한 겉보기용량이 가장 크게 나타났고, 합성수지들은 네오듐(III) 금속이온에 대하여 선택성을 보였다.

The purpose of this study was to analyze and compare the contents of minerals and ionic components in domestic commercial natural mineral waters, and to investigate the relationship between water quality and characteristics of suspended and rocks there of its source. All mineral waters tested in this study met the korean mineral water quality guideline, although chemical components varied widely depending upon the geological characteristics and degree of urbanization of the source area or physical water treatment method. The water quality of commercial bottled water was different from that of source water, especially in cationic components, and showed a tendency to become worse with time elapsed. The water quality on the bottle was also different from the measured quality.

This study was investigated to the reaction of alumina sintering with alkaline. The soluble $NaAlO_2$ was made after the commercial ${\alpha}-Al_2O_3$ was calcinated with NaOH. The reaction of alumina was carried out to be based on the effects of calcination temperature, time, and the mixing ratio of ${\alpha}-Al_2O_3/NaOH$. The alumina was calcined over $500^{\circ}C$ with NaOH powder after it was sieved with 170/270 mesh. The calcined alumina with NaOH powder was dissolved into $25^{\circ}C$ distilled water and filtrated, and HCI was added to adapt pH 6.5~7.5. The residue was separated with vacuum pump for filtration after it was adapted to proper pH, and aluminum compound was precipitated with $Al(OH)_3$. The investigation was carried out with the variables; the calcination temperature($500-900^{\circ}C$), the calcination time (30~90 min), and the concentration of HCI when leaching(0.5~3.0N) respectively. In this investigation, the main product of ${\alpha}-Al_2O_3$ and NaOH was $NaAlO_2$ and the maximum conversion ratio was 91.4% under the optimum conditions as followed ; the ratio of NaOH/${\alpha}-Al_2O_3$ was 1.5 and the calcination conditions were $800^{\circ}C$ and 90 min.

Seasonal variation of $NO_2$ and $SO_2$ concentration was investigated at the underground shopping center in Chonan from October 1997 to August 1998. $NO_2$ and $SO_2$ was collected by personal air sampler at $0.4{\ell}/min$ and $0.5{\ell}/min$ respectively and analyzed using UV spectrophotometer at 550nm and 548nm individually. The results were as follows. 1. The concentration of $NO_2$ was 0.070 ppm in spring, 0.068 ppm in summer, 0.074 ppm in autumn and 0.085 ppm in winter. There was no significant difference. 2. The concentration of $SO_2$ was 0.0233 ppm in spring, 0.0216 ppm in summer, 0.0188 ppm in autumn and 0.0621 ppm in winter. There was significant difference (p<0.01). 3. The higher concentration of $NO_2$ and $SO_2$ gases were shown near the cafeteria (p<0.001, p<0.05). 4. The higher concentration of $NO_2$ was observed at indoor than the underground passage. There was significant difference between two values (p<0.01).

This study was designed to investigate the quality of the simplified water supplies by regional groups in Uijoungbu. For this objective physicochemistric and microbiological experiment were performed. Simplified water in Uijoungbu(Howondong Darakwon, Singokdong Chudong, Songsandong Mangadae, Songsandong Gacbawe, Songsandong Gusungmal, Songsandong Baebul, Ganeung3dong) tested by this study physicochemistric elements suited the test. However, Songsandong Mangadae exceeded the minimum level suggested as $NO_3-N(10mg/{\ell})$. The population of general bacteria were exceeded the minimum level suggested as drinkable water(less than $100CFU/m{\ell}$). Some simplified water in Uijoungbu were proven to be contaminated.