Seung Hwan Lee , Kyu Hong Ahn

DOI: JANT Vol.13(No.4) 345-352, 1997

Excessive phosphorus (P as orthophosphate) is one of the major pollutants in natural water that are responsible for algae blooms and eutrophication. P removal by soil is an attractive solution if the P sorption capacity of the soil is significant. To design an efficient land treatment facility, basic information on the behavior of P in the media and water environment is required. In this study, detailed column experiments were conducted to study the P transport under dynamic condition, and mathematical models were developed to describe this process. The column experiments conducted with a sandy loam soil from North Sydney, Australia, as an adsorbing medium indicated its high sorption capacity of P. P transport in the soil column exhibited characteristic S-shaped or curvilinear breakthrough curves. The simulated results from a dynamic physical non-equilibrium sorption model (DPNSM) and Freundlich isotherm constants satisfactorily matched the corresponding experimental breakthrough data. The mobility of P is restricted by the adsorbent.

Seung Hwan Lee , S . Vigneswaran , Kyu Hong Ahn

DOI: JANT Vol.13(No.4) 353-361, 1997

Proper estimation of phosphorous (P as orthophosphate) removal rate is one of the important factors to consider for the design of an efficient land treatment facility. As wastewater containing NH₄^+ in addition to P flows along the hydraulic channel, detailed batch (static) and column (dynamic) sorption experiments for P removal onto slag media from BHP steel industry, Australia, were conducted to study the effects of agitation and NH₄^+ concentration. It took almost 3 times to adsorb more than 90% of the P in the system without agitation. Kinetics of P sorption gives satisfactory predictions by a static, physical, non-equilibrium sorption model (SPNSM) using Freundlich isotherm constants. Effect of agitation was quantified by using the distribution and fluctuation of film transfer constants. The experimental results show that P sorption is slightly affected by agitation. Both for the batch and column experiments on P sorption in the slag, the amount of P adsorbed by which is reduced in the presence of NH₄^+. This reduction was more significant in the static condition. The percentage of P reduction in the presence of NH₄^+ in the dust solution ranged from 33 to 57% depending on the initial P concentration. The average reduction of P sorption in the cake solution was 10% .

이승환 , 안규홍 Seung Hwan Lee , Kyu Hong Ahn

DOI: JANT Vol.13(No.4) 363-372, 1997

Crossflow microfiltration is a pressure driven membrane process allowing better permeate flux by shearing action of flow. It can remove most of the impurities found in water and wastewater. But there are still main problems to be solved due to fouling, deposition and internal clogging, which reduce the efficiency of separation. Inline flocculation CFMF (Cross Flow Micro Filtration) with pulsation cleaning technique was found to be one of the desirable techniques to avoid or minimize these drawbacks. In AIT(Asian Institute of Technology) domestic wastewater treatment, alum along with PAC (Powdered Activated Carbon) were added to investigate the performance of this system. Optimal amount of alum and PAC dose which corresponded to maximum flux was clear while the increase of the chemicals produced better effluent quality. The comparison of pulsation cleaning technique at different chemicals doses indicated that this technique was more effective in improving the permeate flux when PAC along with alum was added than no chemicals or any alum was added. This improvement was 26%.

정영희 , 김삼권 , 신선경 , 이재인 , 이원석 , 이준배 Y . H . Chung , S . C . Kim , S . K . Shin , J . I . Lee , W . S . Lee , J . B . Lee

DOI: JANT Vol.13(No.4) 373-383, 1997

The monitoring technique for trace organic pollutants is developed to find the pollutant and solve the environmental accident by persuiting the effluent source. Twenty five samples of the inffluent, effluent and stream water were collected to apply the monitoring technique for trace organic pollutant in the Imjin liver. In Mumyung stream, the collected samples from pollutant source of the downstream are analyzed. The peak patterns of volatile organic compounds such as sulfur compounds, toluene and indene compounds agreed to the leather factory and the peak patterns of semivolatile organic compounds such as phosphate compounds agreed to the foundry. In Hyochon stream, the volatile organic compounds such as trichlorobenzene, naphthalene, benzene and toluene are detected in the main stream of the Shin stream. These peak patterns agreed to the effluent peaks of painting and textile manufacturing industries. Also, the peak patterns of semi-volatile organic compounds (phenol compounds and hydrocarbons of high boiling point) conformed to the furs manufacturing industry. In Sangpai stream, the collected samples from midstream of Sangpai stream are detected the trichlorobenzene and trihalomethans as volatile organic compounds. These characteristic organic pollutants are generally discharged from the textile & dyeing based on the established database. From these information, we found that the wastewater is discharged from two textile industries as the result of pursuit. The semi-volatile organic compounds, which are indole and phenol compounds, also accorded to the peak patterns of textile & dyeing.

Jong Tae Jung , Jin Han Kim

DOI: JANT Vol.13(No.4) 385-391, 1997

A simpler, easier and more effective tool to study biodegradation of organic compounds by controlling the parameters, dissolved oxygen(DO) and pH is presented. Microorganisms from activated sludge are entrapped in calcium alginate gel, and are used in a packed-bed batch recirculation reactor to study degradation of organic compounds such as methyl methacylate(MMA), styrene, ethylene glycol and tetraethylene glycol(TEG). It is shown how preliminary but useful information can be easily generated about degradation of a compound by on-line measurement of DO and pH without detailed analysis of the substrate. This design can also be incorporated in a biodegradation process, thus eliminating the need for continuous analysis of the substrate. DO is used as a rate limiting substrate and is supplied to the reactor controlled by a set point or time based control. The DO and pH profile clearly show different stages (initiation, acceleration, completion) of the reaction. From these profiles the degradation rates of the organic compounds in question can be estimated easily.

구이경 , 황덕흥 , 이상봉 , 김동윤 Lee Kyoung Ku , Deok Heung Hwang , Sang Bong Lee , Dong Youn Kim

DOI: JANT Vol.13(No.4) 393-400, 1997

Since 20th century began, chlorine has been used as a primary disinfectant for the water treatment. But it was suggested that disinfection by chlorine should be modified because the undesirable disinfection byproduct such as THMs had been found in drinking water. And so this study was carried out to understand the characteristics of chlorine demand variation through the water treatment process. Investigated results from this study were as following. The short term and the total chlorine demand during research period in Nakdong river, varied over the range of 3.09∼6.69 and 4.78∼9.78㎎/ℓ, respectively. The total chlorine demand was reduced about 80% after BAC filtration. Because NH₃-N reacted with chlorine rapidly, this reaction influenced the short term chlorine demand and the mean correlation coefficient was 0.99. The relationship between chlorine demand and NBDOC among DOC portion showed low correlation coefficient of 0.24, but that between chlorine demand and BDOC showed high correlationship. The correlation coefficients of 4hr, 72hr and 168hr were 0.77, 0.88 and 0.87, respectively.

김응호 , 허순철 , 조진규 Eoung Ho Kim , Soon Cheol Hur , Jin Kyu Cho

DOI: JANT Vol.13(No.4) 401-406, 1997

Calcium ion and pH of leachate from converter slag as phosphorus crystallizer were measured with respect to diameter and space velocity(SV) for stable crystallization. Since conventional crystallization process in municipal wastewater treatment requires calcium concentration over 70㎎/L and usually secondary effluent includes Caz^(2+) concentration of 40㎎/L, it must be leached above 30㎎/L from converter slag itself which is the critical concentration to judge the effective slag duration. Diameter of used slag was ranged from 0.4 to 2.0㎜. As the leaching pH of all slag media is over 11.0, the slag process needs the additional pH decreasing adjustment. When using below l.0㎜ diameter of slag media under the space velocity of 2hr^(-1), the effective duration lasted 40days. When using slag ranged from 0.42 to 2.0㎜ under the space velocity of lhr^(-1) and 2hr^(-1) , the effluent Ca^(2+) concentration maintained over 30㎎/L until 40days, but in case of SV of 3hr or above the critical 30㎎/L cannot be obtained from initial operation.

성동모 , 윤태일 Dong Mo Sung , Tai Il Yoon

DOI: JANT Vol.13(No.4) 407-414, 1997

When the artificial kaoline suspension was coagulated with coagulants, the effect of pH were studied. After temperature of suspension were adjusted to 5℃ and 25℃, the experiments were conducted by the Camp type jar tester. The floc formation process was on-line monitored by PDA(photometric dispersion Analyzer) and the floc characteristics such as residual turbidity and mean floc size were analysed. Flocculation velocity at 25℃ was found to be faster than 5℃. Single inorganic coagulant use and the combined use of inorganic coagulant with the organic polymer showed similar coagulation characteristics. By the PDA results, the temperature effect in case of alum coagulation was smaller than the case of the coagulation by PAC or PACS.

최지용 , 신은성 Ji Yong Choi , Eun Sung Shin

DOI: JANT Vol.13(No.4) 415-425, 1997

To assist in the dissemination of water quality information to expert as well as layman, Korea Water Quality Index(K-WQI) has been developed. The K-WQI is based on ten physico-chemical and biological determinants which were adopted by an intensive interview and questionnaire survey, and a review of water quality criteria. The sub-index is developed by use of both opinion research and mathematical techniques. The former involves the completion of a series of questionnaires by a panel of water experts thus facilitating the objective selection, transformation and weighting of determinants. The latter involves the use of regression for the construction of the sub-index functions. Aggregation for sub-index is used weighted product function. The weighted product, when applied to decreasing scale subindices, does not exhibit eclipsing. Application of the K-WQI to water quality data, drawn from a selection of Korean river reaches typifying a range of river qualities, has shown that the Index not only act as indicators of water quality change, but can also indicate the effects of these changes on potential water use.

이상형 , 이준상 , 전항배 , 박종호 Sang Hyung Lee , Jun Sang Lee , Hang Bae Jun , Jong Ho Park

DOI: JANT Vol.13(No.4) 427-433, 1997

In this research, an wasted washing machine was remanufactured to a sequencing batch reactor(SBR) and investigated for treating swine wastewater with it. This SBR system was operated for removing COD, ammonia, and suspended solid, that were the major pollutants in animal wastewater. Aerobic and anoxic conditions after FILL were applied intermittently for effective removal of nitrogen. SETTLE and DRAW modes were followed by the complete aerobic and anoxic REACT. The total volume of the SBR was 75 liters, while the working volume in a cycle was 35 liters. When the final operating strategy of the SBR was FILL/REACT/SETTLE/DRAW of 0.5/10/1/0.5 hr, the removal efficiencies of TCOD_(Cr), NH₄-N, and T-N were 95, 98, and 85%, respectively. Finally, this SBR system can handle 10(based on 70㎏) pigs effectively.

김영주 Young Ju Kim

DOI: JANT Vol.13(No.4) 435-440, 1997

In order to remove ammonium for tannery wastewater, electrochemical-oxidation using packed activated carbon was investigated. As electrode, platinium platinized anode and stainlessteel 316L cathode were used. Ammonium elimination was influenced by concentration of chloride, electrical dencity and negatively influenced by the presence of organic compounds. Ammonium elimination efficiency after 15min of electrolysis at a current dencity of 7.9A/dm² and chloride concentration of 11,000㎎/L was equal to about 99.5%. The removal efficiency of chemically and biologically treated wastewater was about twice as good as anly chemically pretreated wastewater. Electrooxidation using paked activated carbon proved more efficient about 50% than the conventional electrical oxidation system. In conculusion electrochemical oxidation system can be used as a polishing step for the biological step for the treatment of tannery wastewater.

류동춘 , 정형숙 , 양병수 Dong Choon Ryou , Hyung Sook Chung , Byung Soo Yang

DOI: JANT Vol.13(No.4) 441-450, 1997

In advanced water treatment, it has been reported that pre-ozonation attributed to the preceeding processes through the enhancement of coagulation by the oxidation of algae, organic, and inorganic matters in the raw water as well as it enhanced the quality of the treated water by preventing the formation of the disinfection by-products. In this research, in order to find the effects of the pre-ozonation on the conventional water treatment system with raw water from the Nak-dong River and to get the optimal design factors and the operational conditions of ozone, the followings were concluded from the batch experiments. 1. The variation of DOC and UV-254 concentrations during ozone oxidation of raw water were not much at the ozone dosage of 2 to 3㎎/ℓ and contact time of 3 to 5minutes, while the disinfection efficiency for algae based on chlorophyll-a concentration was increased according to the increase of ozone dosage and contact time. 2. At the coagulation-sedimentation test followed by pre-ozonation, turbidity removal efficiency was not improved apparently independent from ozone contact time. But the capability of coagulation was increased compared to the case without preozonation. 3. Optimal ozone dosage to the raw water will increase the DOC and UV-254 removal efficiencies through the coagulation improvement. 4. The optimal operational conditions for pre-ozonation to improve the efficiency of the coagulation -sedimentation process in the existing water treatment plant were found to be ozone dosage of 2 to 3㎎/ℓ and contact time of 3 to 5 minutes. 5. Based on this experiment, the pre-ozonation may improve the raw water quality in the Nak Dong River.