• Journal of Korean Society on Water Environment
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• v.20 no.5
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• pp.409-414
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• 2004

Pilot-scale experiments were performed for the treatment of bank filtrate contammg high manganese concentration around 2mg/L using rapid manganese sand filtration to investigate effects of oxidant dose and pH control on the removal efficiency of manganese. For theoretical dose ranges of oxidant (sodium hypochlorite) between 3 and 4mg/L, the manganese concentration of effluent was 0.57 mg/L, which corresponded to 72.5% removal and was higher than drinking water quality standards of 0.3mg/L. For excess dose ranges of oxidant between 4 and 8mg/L, the manganese concentration of effluent was reduced to 0.14mg/L, which corresponded to 94.5% removal, but the residual chlorine concentration was over 1.0mg/L. On the other hand, manganese removal efficiency drastically increased up to the value of 98.0%, which is equivalent to the effluent concentration of 0.03mg/L by controling pH to the range between 7 and 8 for the theoretical dose of oxidant. Consequently, these results indicated that appropriate dose of chemicals, such as oxidant and alkali, and continuous monitoring of manganese should be necessary to obtain efficient removal of manganese and to optimize the maintenance of treatment facilities for the treatment of bank filtrate with high concentration of manganese.

• Journal of Animal Science and Technology
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• v.48 no.2
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• pp.315-324
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• 2006

This research was conducted to clarify the characteristics of electrochemical decolorization of effluent discharged from a biological animal wastewater treatment process and to finally establish parameters or mode for optimum operation of electrolysis system. Average color unit of wastewater was about 1,200 and DSA(Dimensionally Stable Anode) was used as electrode. Experiments were performed with two different operation conditions or modes, fixed voltage-free current(Run A) and free voltage-fixed current(Run B). Color removal rate was proportional to the electrode area and electrical conductivity, and an equation subject to them at a condition of fixed voltage was derived as follows; Ct=C0ekt, k=[{0.0121×ａ(dm2)× c(mS/cm)}+0.0288], [where, C0: initial color, Ct: color unit after treatment for t, k: reaction coefficient, t: time(min.), ａ: electrode area, c: conductivity]. From the study on the effects of current density on color removal, it was revealed that the removal efficiency of color was function of the current density, showing direct proportion. However, when considered energy consumption rate, maintenance of low current density was an economical way. Based on the obtained results, it was concluded that supplementation of electrolyte is not necessary for the removal of color from the effluent of secondary treatment process and operation with the mode of free voltage-fixed current, rather than operation with fixed voltage-free current mode, would be an efficient way to increase the removal performance and capacity per consumed energy.

• Environmental Engineering Research
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• v.11 no.3
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• pp.134-142
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• 2006

The treatment of high-strength swine wastewater by anaerobic digestion combined with an aquatic plant system was investigated. Anaerobic digestion of swine wastewater gave volatile solids (VS) removal efficiencies of 43.3%, 52.1% and 54.5% for hydraulic retention times (HRTs) of 20, 30, 40 days, respectively. The removal efficiencies of VS, total chemical oxygen demand (TCOD) and soluble chemical oxygen demand (SCOD) decreased with increasing VS volumetric loading rate (VLR). Higher organic removal efficiency was observed at longer HRTs for the same VS volumetric loading rate. As VS volumetric loading rate increased, biogas production increased and the methane content of the biogas decreased. Experiments using duckweed (Lemna species) as an aquatic macrophyte gave the following results. In the case of nitrogen, removal efficiency was above 60% and effluent concentration was below 10.0 mg/L when the influent ammonia-N loading was about $1.0\;g/m^2/day$. In the case of phosphorus, removal efficiency was above 55% and effluent concentration was below 2.0 mg/L when the influent $PO_4$-P loading was about $0.15\;g/m^2/day$. In addition, crude protein and phosphorus content of duckweed biomass increased from 15.6% to 41.6% and from 0.8% to 1.6%, respectively, as the influent nutrient concentration increased. The treatment of high-strength swine wastewater by anaerobic digestion combined with an aquatic plant system offers good performance in terms of organics and nutrient removal for relatively low operation and maintenance costs. The results indicate that under appropriate operational conditions, the effluent quality is within the limits set by Korean discharge criteria.

• Journal of Environmental Science International
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• v.13 no.10
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• pp.911-919
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• 2004

The purpose of this research was evaluated economical effect to apply alternative external carbon source. Conventional activated sludge process in municipal wastewater treatment plant was adapted and introduced to Biological nutrient removal processes to meet the newly enforced effluent quality standard for nutrient removal in Korea. Low $COD/NH_4^+-N$ ratio and higher nutrient concentration of influent characteristics force to inject external carbon source for denitrifying recycled nitrate. In the most case, methanol was used as external carbon source. But Methanol is expensive and very dangerous in handling. So we could find cheaper and safer external carbon source substituted methanol in last study. This alternative external carbon source is named RCS(recoverd carbon source) and a by-product of fine chemical product at chemical plant. When RCS was applied real municipal wastewater treatment plant, average $55\~65\%$ of T-N removal efficiency, 8.8mg/l of effluent T-N concentration, 11.3mg/l of effleunt COD concentration were obtained without effluent COD increase as against used methanol. To apply RCS in municipal wastewater treatment plant obtain approximately $\74.5%$ expenditure cost reduction in comparison with methanol dosage cost.

• Proceedings of the Korean Society of Environment and Ecology Conference
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• 2003.10a
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• pp.105-126
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• 2003

In Korea most of annual rainfall is concentrated in several episodic heavy rains during the season of summer monsoon and typhoon. Because of uneven rainfall distribution many dams have been constructed in order to secure water supply in dry seasons. The Han River system has the most dams among Korean rivers, and the river is a series of dams now. Reservoirs need different strategy of water quality control from river water. Autochthonous organic matter and phosphorus should be the major target to be controlled in lakes. In this Paper some problems are discussed that makes efforts of water quality improvement ineffective in lakes of Korea, even after the substantial investment to wastewater treatment facilities.1) Phosphorus is the key factor controlling eutrophication of lakes and the reduction ofphosphors should be the major target of water treatment. However, water quality management strategy in Korea is still stream-oriented, and focused on BOD removal from sewage. Phosphorus removal efficiency remains as low as 10-30%, because biological treatment is adopted for both secondary treatment and advanced treatment. The standard for TP concentration of the sewage treatment plant effluent is 6 mgP/l in most of regions, and 2 mg/l in enforced region near metropolitan water intake point. TP in the effluents of sewage treatment plants are usually 1-2 mg/1, and most of plants meet the effluent regulation without a further phosphorus removal process. The generous TP standard for effluents discourages further efforts to improve phosphorus removal efficiency of sewage treatment. Considering that TP standard for the effluent is below 0.1 mg/l in some countries, it should be amended to below 0.1 mg/l in Korea, especially in the watershed of large lakes.2) Urban runoff and combined sewer overflow are not treated, even though their total loading into lakes can be comparable to municipal sewage discharges on dry days. Chemical coagulation and rapid settling might be the solution to urban runoff in regard of intermittent operation on only rainy days.3) Aggregated precipitation in Korea that is concentrated on several episodic heavyrains per year causes a large amount of nonpoint source pollution loading into lakes. It makes the treatment of nonpoint source discharge by methods of other countries of even rain pattern, such as retention pond or artificial wetland, impractical in Korea.4) The application rate of fertilizers in Korea is ten times as high as the average ofOECD countries. The total manure discharge from animal farming is thought to be over the capacity of soil treatment in Korea. Even though large portion of manure is composted for organic fertilizer, a lot of nutrients and organic matter emanates from organic compost. The reduction of application rate and discharge rate of phosphorus from agricultural fields should be encouraged by incentives and regulations.5) There is a lot of vegetable fields with high slopes in the upstream region of the HanRiver. Soil erosion is severe due to high slopes, and fertilizer is discharged in the form of adsorbed phosphorus on clay surface. The reduction of soil erosion in the upland area should be the major preventive policy for eutrophication. Uplands of high slope must be recovered to forest, and eroded gullies should be reformed into grass-buffered natural streams which are wider and resistant to bank erosion.

• Journal of Korean Society on Water Environment
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• v.27 no.2
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• pp.200-209
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• 2011

The purpose of the study is to optimally manage sewage treatment plant with analysis of phosphorus contribution and improvement of water quality contributing rate in the effect of inflowing point of effluent and Pal-Dang lake after reducing T-P discharge from large scale public sewage treatment plant at upstream of Pal-Dang lake. Also, this study, for enforcement of T-P in effluent, plans optimal management of effluent T-P through examining propriety of environmental, technological, and economical aspect such as water quality standard of domestic and foreign T-P and related policy. In regarding optimal management of T-P discharged from public sewage treatment plant located in upstream of Pal-Dang lake, the study drew following conclusions. With the optimal management of public sewage treatment plant, it showed that a pollution level became higher in the order of Sumgang E in South-Han river, C in Dalcheon, B1 B2, A in North-Han river, and J in Kyungancheon, and it is required reduction of T-P first. The highest value in analysis of benefit-costs from sewage treatment plant in the selected research area was Kyungan B, and the others are with the order of Jojong A, Bokha A, Kyungan A, and Yanghwa A. With result of this study, all 14 areas are required more enforced phosphorus treatment. The study resulted that the most top priority areas were Hangang F, Sumgang B, and Gyungan A, top priority areas were Bokha A, Dalcheon B, and Cheongmi A, priority areas were Hangang E, Heukcheon A, Gyungan B, and Jojong A, and potential areas were Sumgang A, Yanghwa A, Dalcheon A, and Hangang D. It seems to be appropriate to apply 0.2 mg/L of T-P treatment for water supply source reservation, 0.5 mg/L for the other areas by locally, and 0.2~0.5 mg/L for biological nitrogen phosphorus treatment method and 0.5~1 mg/L for Conventional Activated Sludge by technologically. Also, it may be appropriate to apply 0.2 mg/L for the most top priority area(I), 0.3 mg/L for the top priority area(II), 0.4 mg/L for priority area(III), and 0.5 mg/L for potential area(IV) by the separation of priority area.

• Journal of Korean Society on Water Environment
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• v.23 no.5
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• pp.766-775
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• 2007

The use of toxic chemicals was extended as the industry in Korea has grown dramatically during the last three decades. However, list of toxic substances and limit concentrations in the water environment are not consistent within management of ambient water, drinking water and industrial effluent. This article suggests the systematic framework to classify toxic substances in the water environment and deriving their effluent limits. The most important factor for decision-making to classify toxic substances is whether their concentrations in the water environment are higher than the reference concentrations, estimated by considering human health risk and ecological risk. Using a risk-based reference concentration, the ambient water quality criterion, it is possible to derive the regulatory limit concentrations of toxic substances in drinking water and in industrial effluent. The goal concentrations in the effluent, which guarantee the human and ecological safety, should be determined with scientific investigation, balancing environmental benefit and economical effect, considering availability of treatment technology and identifying characteristics of wastewater from different industries.

• Korean Chemical Engineering Research
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• v.55 no.6
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• pp.822-829
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• 2017

As a method to reduce the total phosphorus in sewage treatment plant, we applied the integral type slow mixing/sedimentation fiber filtration system to compare the control methods for the sewage effluent and the reject water. It was analyzed that about 92.4 kg T-P/day should be removed in order to satisfy the final concentration of phosphorus of 0.2 mg T-P/L, which is reinforced effluent standard. Therefore the total phosphorus removal efficiency should be 96% for sewage effluent and 69.2% for reject water (dehydrated filtrate) respectively. The system operation cost to achieve the target of total phosphorus removal efficiency was assessed. It has been found that the treatment cost of the reject water containing high concentration of phosphorus with a low flow rate is reduced to about 1/2.4 of the coagulant cost and about 1/120 of the electricity cost, compared to that of the sewage effluent treatment. Also the economics of the integral type slow mixing/sedimentation fiber filtration system and the general coagulation and sedimentation system were compared. It was evaluated that the development system was more economical because the installation area of the integral type slow mixing/sedimentation fiber filtration system was about 1/7 smaller than that of the general coagulation and sedimentation system, and the annual operation cost including the required amount of coagulant and electricity cost of the development system was lowered about 1/1.7 than that of the general system.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.5
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• pp.326-334
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• 2012

To determine the concentrations and the mass flow of selected 10 perfluorinated compounds (PFCs), a field study was conducted in a wastewater treatment plant. Raw influent, primary influent, primary effluent, aeration tank effluent, secondary effluent, final effluent, dehydration liquor, primary sludge, thickened sludge, final sludge were collected over 3 days in the summer and the winter respectively. Collected samples were equally mixed and then served as an analytical sample. Total 10 compounds were analyzed. In terms of treated water, the concentration of perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA) were in range of N.D.~26.29 ng/L and N.D.~38.15 ng/L respectively. Perfluorononanoate (PFNA) and perfluorohexanesulfonate (PFHxS) were ranged from N.D. to 36.79 ng/L and from N.D. to 24.36 ng/L. In terms of sludges, a concentration of PFOS, PFOA, and perfluorodecanesulfonate (PFDS) were detected from 6.82 to 59.37 ng/g, from 0.13 to 0.37 ng/g, from N.D. to 0.83 ng/g respectively. Mass loading for PFCs increased during wastewater treatment except for PFNA. The observed increase in mass flow of PFCs may have resulted from biodegradation of precursor compounds.

• Journal of Environmental Health Sciences
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• v.7 no.1
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• pp.9-20
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• 1981

This study was performed to determine the correlationship between temperature and overall removals of BOD, SS and to demonstrate the effect of temperature on treatment performance. These data for a period from February 1, 1977 to January 31, 1980 were obtained from the Cheong-Gye Cheon Sewage Treatment plant. The results of correlation and stepwise multiple regression analysis were as follows. 1) Secondary effluent BOD and SS showed negative correlationship with water temperature, with correlation coefficient of -0.1710, and -0.1654 respectively. 2) Correlation coefficient of BOD, SS removal rate and water temperature were 0.1823 and 0.0429 respectively. 3) Regresion equation for estimate of BOD removal rate was as follows $\widehat{Y}_1$ (BOD removal rate)=63.9994+0.5442X(water temperature). And BOD removal rate showed non significant change according to the water temperature. 4) Regression equation for estimate of SS removal rate was as follows $\widehat{Y}_2$ (SS removal rate)=61.6881+0.1514X(Water temperature). And SS removal rate showed non significant change according to the water temperature. 5) According to the Stepwise Multiple Regression analysis, water temperature ranked second order in the BOD removal rate estimation and the equation was as follows $\widehat{Y}_1$ (BOD removal rate)=69.7398+0.2665 $X_1$ (Primary effluent BOD)+0.3562 $X_2$ (Water temperature)-0.0122 $X_3(Flow)+4413.271X_4$ (Organic Loading).