• Resources Recycling
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• v.13 no.3
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• pp.3-11
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• 2004

Basic studies have been conducted regarding the crystal formation of hydroxyapatite which was produced in the treatment process of phosphate-containing wastewater using calcium ions as the precipitating agent for its employment as the material for artificial bones. The precipitation of hydroxyapatite were conducted in the synthetic solution which simulating human body fluid for its increased applicability. Ca($NO_3$)$_2$$.$$4H_2$O and ($NH_4$)$_2$$HPO_4$ were employed for the precipitation of hydroxyapatite and its composition was analyzed after drying at 80oC. The thermal behavior of precipitate was investigated by examining the change in its crystalline structure according to the sintering temperature. DTA/TG analysis showed that the escape of moisture from the precipitate occurred at ca. $100^{\circ}C$ and the decomposition of ammonia and the evaporation of lattice water were brought about at around $250^{\circ}C$. X-ray diffraction analysis indicated that the thermally treated precipitate consisted mainly of hydroxyapatite. For dried precipitate, the bonds in the component materials which used for the precipitate formation were observed by FT-IR, and after thermal treatment the major bonds in the precipitate were shown to be $OH^{-}$, $PO_4^{3-}$ , and $CO_3^{ 2-}$ , which were main comprising bonds of hydroxyapatite.

• Korean Journal of Soil Science and Fertilizer
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• v.30 no.4
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• pp.334-340
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• 1997

It was proven that rice straw can serve can serve as a good support medium for trickling filter with livestock wastewater treatment. The efficiency of removal of removal of environmentally undesirable components from the wastewater by the straw medium was no less inferior to other commonly used support materials. The treated straw was also proven to be a source of abundant plant nutrients. The growth of orchard grass was enhanced greatly by the application of large quantity of the support medium. A maximum yield of dry matter was obtained at the rate of 40 ton/ha. Inorganic NPK elements as background fertilizers were highly recommended for better development in an early stage of growth. The nutritional status of the soil was very much improved by the addition of the medium in terms of exchangeable cations(K, Ca, Mg and Na), available phosphate, and organic matter contents. Nutrient uptake by orchard grass such as N, P and cations was enhanced by rice straw medium treatment and that was proportional to the levels of treatment.

• Korean Journal of Ecology and Environment
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• v.34 no.2 s.94
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• pp.119-125
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• 2001

Total bacterial density was investigated in the main stream and tributaries of the Kyongan Stream and inlet parts of Paltang Reservoir from September 2000 to February 2001 by acridine orange direct count (AODC) method. Total bacterial number in the Kyongan Stream was mainly under influence of the effluent discharge of sewage wastewater treatment plant (SWTP) located in the upstream or downstream. Decreasing rate with water flowing distance (km) in the main stream is $0.13\;{\time}\;10^6$ cells/ml, and it was estimated to much accumulating quantity on the stream bed during transport to downstream. Average values of total bacterial number in September${\sim}$October, November and December${\sim}$February were range $1.74{\sim}3.10{\time}10^6$, $1.86{\sim}7.30{\time}10^6$ and $4.56{\sim}8.75{\time}10^6$cells/ml, respectively, and were high at low temperature than that of high temperature period. Total bacterial number was more abundant at below $10^{\circ}C$ with $2.1{\sim}3.0$ folds than at above $10^{\circ}C$. Water quality by total bacterial number was classify to eutrophic and the potential of wastewater treated effluent for the microbial contamination assessed to very high. The results of this study indicate that the management of point source, SWTP effluent, is urgent to mitigate bacterial impact of Paltang Reservoir as well as the Kyongan Stream.

• Journal of Korean Port Research
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• v.11 no.2
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• pp.231-240
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• 1997

In the United States, a number of ocean outfalls discharge primary treated effluent into deep sea water and contribute for more efficient wastewater treatment. The long multiport diffuser connected by long pipe from a treatment plant discharge wastewater into deep water due to the steep slope of the sea bed. However, Plume discharged from the diffuser can have significant impacts on coastal communities and possibly immediate consequence on public health. Therefore, there have been growing interests about the dynamics of plume in the vicinity of the ocean outfalls. It is expected that the ocean outfall should be considered for more efficient and reliable wastewater treatments as soon as possible around coastal area in South Korea. A number of studies of plume ynamics have used various models to predict plume behavior. However, in many cases, the calculated values of plume behavior are in significantly poor agreement with realistic values. Therefore, in this study, it is recommended that improvements should be made in the application of the plume model to more simulate the actual discharge characteristics and ocean conditions. It should be noted that input parameters in plume models reflect realistic ocean conditions like waves as well as currents. In this study, as one of the new parameters, current and long wave-influenced plume rise and initial dilution have been taken into account by using simple linear wave theory under some specific assumptions for more reliable plume behavior description. Among the improved plume models approved by EPA (Environmental Protection Agency), the RSB(Roberts-Snyder-Baurngartner) and UM(Updated Merge) models were chosen for the calculation of plume behavior, and the variation calculated by both models on the basis of long period wave was compared in terms of plume rise and initial dilution.

• Journal of the Korea Organic Resources Recycling Association
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• v.14 no.3
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• pp.77-84
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• 2006

The objective of this research is to evaluate various reclamation methods of sewage sludge cake after treating with microwave under optimum conditions. In this study the sewage sludge cakes used from S and N wastewater treatment plants in the P city. Microwave with an induced electricity heating way was employed for dehydration of sewage sludge cake. Microwave operation conditions is 2,450 MHz of frequency and the power with 1 to 4 kW. This sewage sludge cake had a moisture content of 70%. The moisture content of the sludge decreased notable up to 2%(wt) resulted in breaking of cell wall. When the treated sewage sludge cake mixed with soils could be applied to use midterm and last cover material soils. Moreover, the adsorption ability of heavy metals such as copper, lead, chromium and cadmium was greatly enhanced by treated sewage sludge cake. Within 30 minutes, 1ppm of copper, chromium and cadmium and 10ppm of lead with 1g of the treated sewage sludge cake in $100m{\ell}$ were below detection. It was possible to use the treated sewage sludge cake as an absorbent for absorption of toxic heavy metals. Results from this research indicated that using of microwave radiation was an effective method for treating sewage sludge cake economically and environmental. A point of view of reclamation, the treated sewage sludge cake appeared to be feasible with an adsorption of heavy metals in steady of using expensive yellow earth.

• Korean Journal of Environmental Agriculture
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• v.26 no.1
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• pp.62-68
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• 2007

Concerns about endocrine disrupting chemicals emitted from humans and animals have been increased because these compounds are detected at very low levels in environment and adversely affect on indigenous fauna. To date, there is little information regarding the concentration of these compounds in animal wastes. In this study, the female hormones, $17\beta-estradiol$ (E2), estrone (E1) and estriol, were measured to provide baseline data in animal wastes. Samples were collected from animal waste storage, methane digester and sludge separated wastewater and analyzed by gas chromatography-mass spectrometry. To measure the mass ratios of estrogen to macronutrients, nitrogen and phosphorous were also determined. Sample collected from animal waste storage had the highest estrogen concentration (98.7 ${\mu}g/L$), while sludge separated wastewater had the lowest concentration (3.4 ${\mu}g/L$). The mean concentrations of E2 and E1 in waste storage sample were (6.8 ${\mu}g/L$) and (68.7 ${\mu}g/L$), respectively. In sludge separated wastewater, the mean concentration of both E2 and E1 were reduced to (2.6 ${\mu}g/L$) and (1.9 ${\mu}g/L$), respectively. However, estriol was not detected in any of the samples collected. Mean ratios of E2 and E1 to macronutrients were significantly different between the methane wastewater and sludge separated wastewater owing to elimination of solid particles.

• Journal of Korean Society on Water Environment
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• v.23 no.3
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• pp.319-323
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• 2007

The Advanced Oxidation Process (AOP) is being increasingly used to oxidize complex organic constituents in treated effluents from domestic wastewater treatment plants. Generally, ${NO_3}^--N$ concentrations ranges between 5 and 8 mg/L for biologically well-treated effluents. However, nitrate ions, ${NO_3}^-$, affects on oxidation as not only a well-known strong absorber of UV light below 250 nm of wavelength but also as an OH radical scavenger. The objective of this study was to evaluate the AOP systems for degradation of 2,4-DCP, and to delineate the effect of nitrate ions on UV oxidation of 2,4-DCP by conducting a bench-scale operation at various reaction times and initial concentrations of $H_2O_2$. The experimental results indicated that 2,4-DCP could be completely oxidized by $UV/H_2O_2$ process with an initial $H_2O_2$ concentration of 20 mg/L at a retention time of 1.0 min or longer. Nitrate ions did not show any adverse effect on 2,4-DCP oxidation at this high $H_2O_2$ concentration, and the practical initial $H_2O_2$ concentration and reaction time for the 80% oxidation turned out to be 5 mg/L and 1.0 min, respectively.

• Journal of Korean Society on Water Environment
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• v.28 no.1
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• pp.1-9
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• 2012

It has been known that Golf course could impose negative impacts on water-ecosystem if pollutant-laden runoff is not treated well. It is important to control non-point source and re-use treated wastewater from the golf course to secure water quality of receiving waterbodies. At golf courses, the rainfall-runoff is affected by various practices to manage grasses. In many hydrological modelings, especially in simple rainfall-runoff modeling, effects on runoff of plant growth and cutting are not considered. In the study, the water erosion prediction project (WEPP), capable of simulating plant growth and various management, was evaluated for its runoff prediction from golf course under grass cutting and irrigation. The %Difference, $R^2$ and the NSE for runoff comparisons were 1.15%, 0.93 and 0.92 for calibration, and 18.12%, 0.82 and 0.88 for validation period, respectively. In grass cutting scenario, grass height was managed to be 18~25 mm. The estimated runoff was decreased by 27%. The difference in estimated total runoff was 11.8% depending on irrigation. As shown in this study, if grass management and irrigation are well-controlled, water quality of downstream areas could be obtained.

• Membrane Journal
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• v.7 no.1
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• pp.39-47
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• 1997

The self-designed membrane system was tested to examine the performance of the hollow fiber type polysulfone ultrafiltration(UF) membrane for the treatment of pure water(the 3rd treated water). The molecular weight cut-off's (MWCO) of the membranes used in this study were 5, 000 and 10, 000, respectively. The recovery rate, the ratio of permeate flow rate to the feed flow rate, increased as the temperature rose. The values of MWCO obtained in this study, using 2, 000 ppm polyethylene glycol and dextran solutions with various molecular weight, showed higher values than those suggested by SKI. Based on the results of the primary experiments, the water of the Gongji-stream, in which water quality is deteriorated by the inflow of domestic wastewater, was selected for the UF membrane test. Biological oxygen demand(BOD), total solids, and turbidity of the treated water had much lower values than those of the source water. Therefore, this study confirmed the possibility of the domestic water treatment using the hollow fiber type UF membrane.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.453-458
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• 2001

This study was performed to reuse the dyeing wastewater sludge treated by Fenton process through the solidification/stabilization technique. To solidify the dyeing sludge the industrial by-products such as blast furnace slag, fly ash and waste sand with cement were used. The laboratory scale and pilot scale test were conducted at room temperature to make construction brick which has high compressive strength and low leaching of heavy metals. The experimental results showed that blast furnace slag and fly ash could be used instead of cement and the products satisfied the regulation of Korean Standards. The blast furnace slag increased the compressive strength and the optimum ratio of slag/dyeing sludge on dry basis was found 0.4. The solidifying agent of SB series could increase rapidly the compressive strength and the optimum ratio of solidifying agent/sludge on dry basis was 0.26 at which the strength was two times compared with non-added condition. The portion of waste and industrial by-products in matrix was over 80%. From the pilot test the optimum pressure in molding was 100kg/$\textrm{cm}^2$ at which the compressive strength was over 100kg/$\textrm{cm}^2$. And the strength increased continuously to 160kg/$\textrm{cm}^2$ until 120 days curing time due to pozzolanic reaction. When SB-20 as a solidifying agent was used, the unconfined compressive strength of dyeing sludge could be obtained 110kg/$\textrm{cm}^2$ which satisfied the regulation of cement brick in Korea Standard(KS).