박재홍 Jae Hong Park , 최의소 Eui So Choi , 공동수 Dong Soo Kong

DOI: Vol.21(No.2) 109-117, 2005

Understanding the condition of our nation`s water resources, identifying what caused problems, and determining how to solve these problems are essential but difficult undertakings. The natural water cycle is itself intricate, and the addition of human activities increased this complexity. Consequently, answering the basic question "How clean and safe is our water?" is not easy. One way to present the condition of our water resources and the impacts of related human activities is to develop understandable measures, or indicators, that singly or in combination provide information on water quality. Managers and scientists can then use this information to develop effective solutions and make sound decisions to protect our water resources. It is important to note that environmental indicators can be used to measure a variety of phenomena. Indicators can present information on status or trends in the state of the environment, can measure pressures or stressors that degrade environmental quality, and can evaluate society`s responses aimed at improving environmental conditions.

Environmental indicators, Water quality, Water resources

서성녀 Seong Nyeo Seo , 김영택 Young Taek Kim , 박철휘 Chul Hwi Park

DOI: Vol.21(No.2) 118-124, 2005

The oxygen solubilized device(O.S.D) and standardized microorganism culture system is more efficient than physical and chemical purification techniques in closed water. This study was to determine how the O.S.D and standardized culture system is efficient in purification capacity in closed water based on the lab scale and pilot plant. In the batch test, inducing the quantitative results from pilot plant operation condition, removal efficiency of COD and TN were about 48.3% and 35% respectively, while SS and chlorophyll-a were 94.9% and 68.7%. The pilot plant results showed that suspended solid(SS) and chlorophyll-a removal efficiency were 60% and 59% respectively, due to coagulation characteristics by standardized culture. Total nitrogen(TN) and total phosphorus(TP)showed good effect for the purification of target pond water quality from field data. Additionally, released velocity was determined in control condition of 5.31 mgPO₄^(3-)·m^(-2)·day^(-1) and 2486.8 mgCOD·m^(-2)·day^(-1). Otherwise, phosphate and COD reflux in the aeration and microorganism condition was showed -9.95 mgPO₄^(3-)·m^(-2) ·day^(-1) and -397.88 mgCOD·m^(-2)·day^(-1). This technology is the most effective not only removal of SS and chlorophyll-a but also control of phosphate and COD release which is very important phenomena in evaluating water quality in closed water like a reservoir and pond.

Oxygen solubilized device, Standardized microorganism, Pond, Reservoir, Purification technology

유순주 Soon Ju Yu , 김창수 Chang Soo Kim , 하성룡 Sung Ryong Ha , 황종연 Jong Yeon Hwang , 채민희 Min Hee Chae

DOI: Vol.21(No.2) 125-131, 2005

Natural organic matter(NOM) is defined as the complex matrix of organic material and abundant in natural waters. It affects the performance of unit operations for water purification. Several kinds of analytical indicators such as DOC, specific ultraviolet absorbance(SUVA), apparent molecular weight (AMW), fractionation and high performance size exclusive chromatography(HPSEC) have been used to understand characteristics and variations of NOM. This study aims to evaluate the characteristics of NOM in the Geum River system comprising with stream flows and reservoirs. It was identified that SUVA denoting the portion of humic substance in water ranged within 1.60~3.36. Using resin adsorbents, dissolved organic carbon(DOC), was fractionated into three classes: hydrophobic bases(HOB), hydrophobic acids(HOA) and hydrophilic substances(HI). HI dominates in all samples, collectively accounting for more than 62% of the DOC. HOA was the second dominated fraction and it varied considerably but accounted for about 30% of the DOC. The distribution of high molecular weight(HMW) measured by HPSEC being used to determine the molecular weight distribution of aquatic humic substances was 40.1% and 38.7% in reservoir and stream flow, respectively. The distribution of low molecular weight(LMW) in stream flow was 13.2% higher than that in reservoir. And apparent molecular weight less than 1KDa, which include the molecular weight of hydrophilic organic matter, occupied with 69.2% and 68.2% in stream flow and reservoir, respectively. While the molecular weight of 1 to 100 KDa including humic substances ranged with 18.6% and 21.6% in stream flow and reservoir, respectively. Seasonal variation of refractory dissolved organic carbon was similar to that of SUVA.

Natural organic matter, NOM, Specific ultraviolet absorbance, SUVA, Apparent molecular weight, High performance size exclusive chromatography, HPSEC, Refractory dissolved organic carbon, Biodegradable dissolved organic carbon

김승준 Seung Jun Kim , 최용수 Yong Su Choi , 홍석원 Seok Won Hong , 권기한 Gi Han Kwon , 정익재 Ik Jae Chung

DOI: Vol.21(No.2) 132-140, 2005

The pilot test of a new alternative for small wastewater treatment system has been conducted for two years. It consists of a hybrid bioreactor and the expert system including the process control logic, PLC system, and HMI for the process automation. In order to monitor and remote control its status, the real-time data was transferred from the on-site control center to the central station via a wireless local area network. More efficient and stable performances were observed at automatic operating mode compared with the manual. On an average, COD, SS, T-N and T-P concentrations in the effluent from the hybrid bioreactor were less than 14, 7, 12 and 0.9 ㎎/L, respectively. According to the result from pilot tests, the quality of treated wastewater with sand filtration was enough to be utilized again.

Hybrid bioreactor, Expert system, Process control Logic, PLC system, HMI system, Small wastewater treatment system

심수용 Soo Young Shim , 김범철 Bum Chul Kim , 호소이요시히코 Yoshihiko Hosoi , 마스다다카노리 Takanori Masuda

DOI: Vol.21(No.2) 141-146, 2005

The aim of this study is to quantify and characterize the dissolved organic carbon (DOC) from paddy fields and crop fields in Tottori, Japan. DOC and ultraviolet (UV) absorption were measured in the filtrated water of each sample. The DOC concentration and the SUVA (specific UV absorption) of biodegradation analysis samples were determined around 50 days after their incubation. In the Fukui paddy fields, DOC concentration varied seasonally from 1.1 to 10.1 ㎎ Cl^(-1), becoming higher during heavy runoffs in April, a non-agriculture period. Variations in DOC concentration did not always correspond to rainfall, though. The Obadake paddy fields showed a DOC concentration pattern similar to that of the Fukui paddy fields. The daily DOC discharge per area in the Fukui (up), Fukui (down), Obadake (south) and Obadake (north) paddy fields influent from paddy fields were 0.02, 0.0161, 0.0135 and 0.0027 ㎏ a^(-1) day^(-1), respectively. These differences resulted from differences in agricultural types and customs of farmers according to paddy fields and other kinds of fields. Also, the SUVAs [which are indirect means to evaluate humic substances (hydrophobic fractions)] of the studied influent waters from paddy fields were generally lower than those of the influent waters from crop fields. Nonbiodegradable DOC accounted for 50.2-98% and 46.8-85.5% of the total DOC in the paddy fields and in the crop fields, respectively.

Dissolved organic carbon, DOC, Paddy field, Non-biodegradable

원성연 Seung Yeon Weon , 박승국 Seung Kook Park , 민경국 Kyung Kook Min , 정근욱 Keun Yook Chung , 전병희 Byong Hee Jun , 이상일 Sang Ill Lee

DOI: Vol.21(No.2) 147-152, 2005

Fermentation efficiencies of organic wastes from the variety of sources were evaluated based on the production of total volatile acids(TVA) in batch reactor. Mixing and pH were not significant factors in producing TVA from the organic wastes. After a 10-day fermentation, final TVA concentrations in piggery, cattle, poultry, and primary settled sludge of domestic wastewater were 8,900, 2,900, 7,370 and 1,630 ㎎/L, respectively. The pH of organic wastes was decreased from neutral to 5.7. The ratio of TVA to NH₄^+-N produced from the animal waste ranged from 11.5 to 30.1, whereas, that in the primary settled sludge of domestic wastewater, was 5.4. Possibility of fermented organic wastes as the electron donors for denitrification in the activated sludge was investigated. In both acclimated and nonacclimated activated sludge, higher denitrification rates were obtained with fermented piggery sludge added than with either methanol or acetate added. The fermented organic acids derived from the primary settled sludge gave the higher denitrification rate (4.2 ㎎ NO₃-N/g vss·hr) in the acclimated activated sludge. Denitrification rate was 1.5 ㎎ NO₃-N/gvss·hr in the nonacclimated sludge with the fermented acids from the primary settled sludge of domestic wastewater added.

Fermentation, Total volatile acids, Primary settled sludge of domestic wastewater, External carbon source, Denitrification

오병수 Byung Soo Oh , 김경숙 Kyoung Suk Kim , 강준원 Joon Wun Kang

DOI: Vol.21(No.2) 153-157, 2005

The purpose of this study was to find out the effect of oxidation by-products for the formation of haloacetic acid (HAA) during ozonation. The phenol was used as a model precursor of HAA, and its oxidation by-products, such as hydroquinone, catechol, glyoxal, glyoxylic acid and oxalic acid were investigated to find out how much HAA formation potential (HAAFP) they have. As the result, among the phenol and its oxidation by-products, the highest reactivity with chlorine was found from the phenol, showing the highest HAAFP. Even though the tested by-products had a lower HAAFP than phenol, it was confirmed that all of them can act as the precursor of HAA. From the ozonation of phenol-containing water, it was found that the efficiency of ozone in controlling of HAAs can be reduced due to the oxidation by-products. In addition, the ozonation of HAAFP was performed under the both pH conditions (acid and base), and the result indicates that OH radical play a important role to decrease HAAFP.

Haloacetic acid formation potential, HAAFP, Ozonation, Oxidation by-product, Phenol

김영철 Young Chul Kim , 안익성 Ik Sung An , 강민기 Min Gi Kang

DOI: Vol.21(No.2) 158-168, 2005

In this study, the discharging effluents from have been 9 municipal wastewater treatment plants surveyed for 1 year-period. Statistics including probability distribution, cumulative occurrence concentration and other statistical parameters were presented. In addition, treatment performance and its stability were also discussed. Most of the plants, have an operational problem of high soluble organic content in the secondary effluent which may be associated with the integrated treatment of human and livestock manures. Nitrogen concentration in the effluents were usually higher during the period of summer and winter. It was found that this is mainly due to lack of the proper C/N ratio during the summer, or/and the effects of low temperature and less dilution by dry weather during the winter. Phosphorus concentration is sharply increased in June. Discussion with plant operators told that it is due to the dissolution of phosphate from the sludge accumulated in the primary settling tanks from the early spring to june. During this period, usually, sludge treatment line is highly overloaded with flush-outs of the sediments also stored in the bottom of combined sewer due to the low flow during winter season. Most of the plants can meet new effluent discharge limits of the nitrogen and phosphorus, and total coliform without further treatment.

Municipal wastewater treatment plant, Treatment performance, Secondary effluent, Stability

최선화 Sun Hwa Choi , 최호진 Ho Jin Choi , 장정렬 Jeon Ryeol Jang , 이승헌 Seung Heon Lee , 오종민 Jong Min Oh

DOI: Vol.21(No.2) 169-175, 2005

This study was carried out to investigate the effects of irrigation water pollution on the yield and grain quality of rice. It acquires fundamental data to set up water quality standards for irrigation and produce agricultural safety products. The correlations of BOD, T-N, T-P, pH, ECw of the irrigation water with yield, grain appearance quality, and the protein content were evaluated. The field and pot experiments were conducted by using Japonica of Oryza sativa L. during 2 years. BOD concentration in irrigation water effects strongly on grain appearance quality and yield of rice. T-N in irrigation water has strong effect on the yield, appearance, and quality of rice. T-P concentration in irrigation water have not any correlation with yield and quality of rice. pH showed strongly negative correlation with maturity ratio(MTR), 1000 grain weight(TGW), and yield of rice(YLD) as r=-0.803~-0.828(p＜0.001) and have no effect on the appearance quality of rice. EC_w indicating salt content showed strongly negative correlation with MTR, TGW, number of grains per panicles(NGP), and number of panicles per unit area(NPM) as r=-0.759~0.798, and with YLD as -0.753.

Irrigation water, Water quality, BOD, T-N, T-P, pH, ECw, Rice yield, Grain appearance quality, Rice quality

백영석 Young Seog Beck , 손진식 Jin Sik Sohn

DOI: Vol.21(No.2) 176-183, 2005

Chlorination of wastewater is recently practiced in Korea. While many researchers have studied the kinetics of aqueous chlorine(HOCl) with nitrogeneous compounds and other organic/inorganic contaminants in drinking water, the researches of wastewater chlorination are relatively few. The purpose of this study was to investigate the chlorine decay kinetics and parameters on wastewater chlorination. Chlorine decay rate increased with increasing initial chlorine concentration. The parameters affecting chlorine decay rate were different in each wastewater treatment plant. One of the most important parameters affecting chlorine decay was initial chlorine concentration, and other parameters such as NH₃-N, total coliform, UV_(254) and Fe were also affected. The decay ratio of chlorine was decreased with increasing initial chlorine concentration, and the disinfection efficiency showed good correlation with the decay ratio.

Total residual chlorine, Chlorination, Wastewater, Chlorine decay rate

여중현 Joong Hyun Yur , 김건하 Geon Ha Kim

DOI: Vol.21(No.2) 184-189, 2005

Impacts of non-point source pollution on water quality are well known. In this paper, effects of land use, precipitation characteristics, discharge characteristics on non-point source pollutant loadings at urban, agricultural and forestry watersheds were discussed. Rainfall runoffs from fifteen rainfall events were sampled and analysed at two urban watersheds, one rural watershed, and one forestry watershed. EMCs (Event Mean Concentration) were calculated based on monitored flow rates and concentrations. Statistical analysis carried out with runoff loadings and affecting variables indicated that runoff loadings are weakly correlated with the rainfall intensity and the dry days before rainfall events while showed no correlations with rainfall depth nor runoff quantity. By comparing EMCs between study watersheds on log-normal cumulative probability scale, EMCs ranking were in the descending order of urban watershed＞agricultural watershed>forestry watershed for SS, TCOD, TN, and TP.

Non-point source, Watershed, Loading, Statistical analysis, Water quality, Rainfall

안지훈 J. H. Ahn , 박종복 J. B. Park , 김성원 S. W. Kim , 박재홍 J. H. Park , 하준수 J. S. Ha , 최의소 E. Choi

DOI: Vol.21(No.2) 190-195, 2005

The laboratory and pilot scale BAFs (biological aerated filters) were operated with 0.3 hr to 1.1 hr EBCT(empty bed contact time) at a maximum filtration rate of 472 m³/m²/day as a treatment method for reuse of secondary effluent and by-pass flow in this study. The effluent BOD and SS were generally 3.5 to 5 ㎎/L and 2 to 3 ㎎/L, respectively with 2ndary effluent, but the SS concentrations increased to 4 to 8 ㎎/L with the increased flow rates of by-pass flow. Potential nitrification rates were very high, but the nitrogen removal efficiencies were low due to the limited carbon sources. Bypass of a part of primary effluent seemed to be desirable to increase the nitrogen removal. Disinfection must be furnished for the reuse of BAF effluent.

BAF, First flush, Nitrification, Reuse, Tertiary treatment, Reuse

김민국 Min Kuk Kim , 전양근 Yang Kun Chun

DOI: Vol.21(No.2) 196-204, 2005

The objective of this study is to evaluate the possibility to apply pre-ozone and membrane system for drinking water. This system is improved in fouling control by pre-ozone system. It is composed of ultrafiltration hollow fiber type membrane and ozone reactor. The result of this study is that the flux is increased about 10.7% and decreased in TMP by the pre-ozone. Also, backwashing pressure decreased about 18%. The optimum concentration of residual ozone is 0.3~0.5 ppm. During the period, the recovery ratio of this system was turned out to be 90% as the flowrate of effluent is 67.1 ㎥/day. When the TMP and backwashing pressure was 0.85 ㎏/㎠ and 1.10 ㎏/㎠, this system was stable without sudden fouling. Finally, the quality of effluent is satisfied the guidelines for potable water quality such as turbidity, color, E.coli, Mn, Al, Fe and so on.

UF membrane, Ozone, Potable water, Membrane fouling, Flux

정용준 Yong Jun Jung , 민경석 Kyung Sok Min

DOI: Vol.21(No.2) 205-210, 2005

There has been a growing interest in NF membrane for drinking water treatment, because it can remove simultaneously both hardness and hazardous micro pollutants such as pesticides and THM precursors. In this work, a hollow fiber NF membrane known as a composite membrane was employed for the rejection properties of both hydrophilic solutes and micro organic pollutants, where the former was used to evaluate the molecular sieving effect of this membrane and the latter was employed for the investigation of solute-membrane interaction as hydrophobic materials. This membrane effectively rejected the hydrophilic solutes and the permeation of them was mainly controlled by the molecular sieving effects such as molecular weight and molecular width. In the case of all micro organic pollutants, the rejections were varied from 42.2% for Simazine to 91.6% for Malathion, and the parameters related to the steric hindrance could significantly play an important role in the rejection. In the batch type adsorption experiments, all micro organic pollutants were entrapped mildly on the membrane in spite of lower degree compared with that of aromatic compounds, and they were correlated with log K.

Rejection property, Micro organic pollutants, Hollow fiber NF, Molecular weight, Molecular width