신응배 , 윤현식 , 이영대 , 이정욱 Eung Bai Shin , Hyun Sik Yoon , Young Dae Lee , Jung Wook Lee

DOI: Vol.10(No.4) 393-399, 1994

Pollutants in wastewater are ranging from dissolved materials with molecular mass to particulate materials well over 100㎛ and it is known that wastewater treatment efficiency is influenced by the size distribution characteristics of pollutants in wastewater. In this work, such analytical techniques as membrane filter technique and gel filtration chromatography are employed to analyze size spectrum of organic pollutants in domestic wastewater. It is observed that a higher fraction of particulate matters is found in raw sewage than in treated effluent, thus exihibiting a larger mass mean diameter (Dmms,o) and the fraction tends to decrease as wastewater flows through treatment processes. It is interesting to note that the dissolved matter constitutes mainly inorganic substances as has been demonstrated by COD/Solids ratios. Three peaks are observed in a molecular mass distribution curve. The maximum is in a range of 10³∼10^5 Molecular Mass, which may contain humic acids, fulvic acids and some proteins in a broad molecular mass spectrum. This highest peak is also found in effluent as well as in influent. Other peaks are in a range of 20∼200 M. M. (synthetic organics, amino acids, nutrients such as nitrogen and phosphorus) and in a range of l.6×10³∼7×10^5 M.M. (large molecule protein, polysaccharides, nucleic acids). These two peaks are also found in treated effluent.

조정우 , 김수철 , 박주영 , 박갑성 Chung Woo Cho , Soo Chul Kim , Joo Young Park , Kap Song Park

DOI: Vol.10(No.4) 400-404, 1994

Ames Mutagenicity assay has been used to evaluate mutagenicity of Kumho river water and chlorinated drinking water. Kumho river water showed negative mutagenic responses both far strains TA98 and TA 100, however the mutagenic ratios increased with. the volume of water samples. Generally, chlorinated drinking water showed positive mutagenic responses. Mutagenic responses were clear in the acid drinking water samples, which suggested that acid chlorinated by-products may induce mutagenicity in the Kumho drinking water samples.

김정규 , 임연택 , 류재근 , 서윤수 Jeong Gyu Kim , Yeong Taek Lim , Jae Keun Ryu , Yoon Soo Suh

DOI: Vol.10(No.4) 405-411, 1994

The treatability of the textile wastewater containing so many kinds of recalcitrant such as organic dyes and PVA (polyvinyl alcohol) is usually poor, because of the high temperature high alikalinity and the recalcitrant containings of the wastewater. Although the major part of textile wastewater treatment plants in Korea consist of a physico-chemical process and a biological process, the treatability is not so high in the reason above mentioned. Therefore, we have developed a new process without physico-chemical pretreatment process, using anaerobic microorganisms which is more resistant for the biotoxicants and recalcitrants. A bench scale reactor of the anaerobic & aerobic (AA) process consists of two anaerobic tanks (2 liters each) and an aerobic tank. The hydraulic retention time(HRT) of anaerobic and aerobic tank was 30 hours and the temperature was setted to 40℃. The dissolved oxygen concentration was maintained at the range of 2∼3 ㎎/ℓ. The reactor was operated with the wastewater from the textile industry which produce cotton and systhetic fiber. This industry has a dyeing and a printing process. The chemical oxygen demand(COD), biochemical oxygen demand (BOD), concentration of PVA, color index and the Microtox biological toxicity were observed for 150 days of operation period. This experiment represents a good treatablity. The removal efficiency of COD, BOD, PVA and color index were 82%, 94%. 98% and 73%, respectively. The causes of this high treatment effciency were primary degradation of recalcitrants and the decreasing of biotoxicity in anaerobic tank.

황규대 , 김복현 Gye Dae Whang , Bok Hyun Kim

DOI: Vol.10(No.4) 412-420, 1994

The objective of this research was to develop and evaluate the combined physicochemical-biological process of phosphorus removal. Four bench scale activated sludge reactors were operated with domestic wastewater generated from Kyung Hee University. Iron electrodes were connected to the aeration basin of three reactors and received an electric current to produce Fe^(3+) formed by the anode dissolution process. One reactor without iron electrode was operated as a control unit. The surface area of iron electrode, phosphorus concentration in influent and operating condition of activated sludge units were changed to study the effect of electrolysis with the iron electrodes. The test results indicated that the electrolysis of iron is an effective way for phosphorus removal and the addition of iron oxide improve the substrate removal efficiency of activated sludge and sludge settling characteristics. It was determined that the effective surface area of iron electrode to obtain 80% of phosphorus removal was 30㎎P/㎠ iron electrode day, and with that condition, more than 90% of TCOD and TSS removal efficiency could be accomplished. It seems that the electrolysis with iron electrode did not affect the biological kinetic coefficients. The obtained yield coefficient(Y) and decay coefficient(K-d), were 0.64㎎MLSS/㎎COD and 0.19day, respectively and were approximately same as the value of conventional activated sludge process.

서정범 , 윤조희 , 임연택 , 조광명 Jeong Beom Seo , Cho Hee Yoon , Yeon Taek Rim , Kwang Myeung Cho

DOI: Vol.10(No.4) 421-426, 1994

To investigate the phosphorus adsorption characteristics of soil, a sandy loam and a phosphate solution were used in this experiment. The results obtained from this study are as follows. The adsorption of phosphorus on soil reached an equilibrium after a contact time of 6 days. The phosphorus adsorption capacity of soil could be well expressed by a Freundlich isotherm Coefficients in the Freundlich isotherm, rate constants and effective pore diffusivities of a naturally dried soil and a soil dried at 100℃ for 6 hours showed similar values. The exponent in the Freundlich isotherm of the naturally dried soil was slightly higher than the one for the soil dried at 100℃ for 6 hours. The adsorption quantity decreased a little when the pH of the solution was increased from 5 to 9

최용수 , 조재현 Yong Su Choi , Jae Hyun Cho

DOI: Vol.10(No.4) 427-434, 1994

This study was conducted to develop an advanced chemical wastewater treatment technology using new coagulants extracted from vermiculite. In order to make an optimal vermiculite extract solution(VES) that includes various cations useful for coagulation, extraction experiments by sulfuric acid were carried out. The characteristic of VES as coagulants was evaluated and compared to the existing inorganic coagulants, alum and ferric chloride. According to the experimental results, the concentrations of Al^(3+), Fe^(3+), ㎎^(2+), and Si^(4+) cations in VES were increasing with the increase of particle sizes, sulfuric acid concentration below 10N, temperature up to 100℃. and agitation time. It is found that VES can be applicated to the treatment of alkaline wastewater without pH control, because VES has various cations to make a coagulation with suspended colloids in a diverse pH range. The SS and COD removal efficiencies from the tannery wastewater by the dose of 0.2g-vermiculite(23.8㎎-Al^(3+), 27.6㎎-Fe^(3+), 33.6㎎-㎎^(2+), 0.2㎎-Si^(4+))/ℓ VES were higher than 80% and 30%, respectively, and independent on pH values. Especially a high COD removal rate of 61% was shown at the dose of 0.6g-vermiculite (72㎎-Al^(4+), 82.8㎎- Fe^(3+), 100.8㎎-㎎^(2+) , 0.6㎎-Si^(4+))/ℓ VES. However dosage more than lg(78.9㎎- A1^(3+))/ℓ of alum or 0.5g(103.6㎎-Fe^(3+))/ℓ of ferric chloride was required to maintain SS removal rates higher than 80%. Alkalinity and pH in the reactor decreased with the dose of VES, for example pH value of tannery wastewater decreased to 8 at the dose of 0.4g- vermiculite(47.6㎎-Al^(3+), 55.6㎎-Fe^(3+), 67.6㎎-㎎^(2+), 0.4㎎-Si^(4+))/ℓ VES. Turbidity removal rates in the reactor were 91∼93% at the dose of 0.l∼0.3g/ℓ VES. Another advantage from the coagulation by VES is less sludge generation in comparison with other inorganic coagulants.

고영송 , 남상호 Young Song Ko , Sang Ho Nam

DOI: Vol.10(No.4) 435-442, 1994

In public water supply systems, Alum and/or PAC has been used as a coagulant. It is well known that in general their use led residual aluminum concentration increased in filtered water. This study was conducted to investigate the optimum conditions that both the concentration of residual aluminum and turbidity are minimized. At the same time, the physical characteristics of floc such as floc strength. floc settling rate, floc size and type were observed. The results obtained at a given experimental condition can be summarized as follows. With the increase of mixing rate, rapid and slow, both the concentrations of residual aluminum and turbidity were increased and the same trend was observed in increment of mixing time. The size of floc produced was smaller in high rapid mixing rate, and the larger floc was more complex in the shape. The mean size of floc produced was 33-63㎛ in diameter. The concentrations of residual aluminum and turbidity were increased with the increment of mechanical floc breakup strength. When the degree of floc breakup was large. the reunion capacity was more deteriorated, by consequent, the flocs showed slow settling rate.

윤주환 , 박재형 Zu Whan Yun , Jay Hyung Park

DOI: Vol.10(No.4) 443-450, 1994

One of the current issue in this country is that the existing sewage treatment plants have to find economically feasible alternatives to meet more stringent effluent standards of both SOD_5 and SS of 20㎎/L in 1996. In order to meet the stringent effluent limitations with a simple process modification, add-on treatment of the secondary effluent using the aerated upflow biological fixed-film(ABF) reactor was examined. The primary effluent taken from the sewage treatment plant was overloaded to the laboratory activated sludge unit in order to produce an effluent with both BOD and SS of near 30㎎/L. The activated sludge effluent was then fed to the ABF unit with crushed stone medium. The volumetric organic loading to the ABF unit was maintained in the range of 0.42 to 0.66㎏ BOD_5/㎥·d. Various operation mode of aeration in ABF unit was examined. For 146 days of the experimental period, it has been found that the ABF could produce a high quality effluent without any clogging problem. In addition, the solids carry-over from the ABF was exceptionally good in settle ability and dewaterability.

한무영 Moo Young Han

DOI: Vol.10(No.4) 451-454, 1994