• Journal of Korean Society of Environmental Engineers
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• v.33 no.11
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• pp.783-789
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• 2011

Recently, auto-thermal thermophilic aerobic digestion (ATAD) has a great attention for destruction of wasted sludge biomass in wastewater treatment plant. Reduction of sludge concentration has been successfully achieved with pilot scale ATAD and ceramic filtration process in field condition. However, high concentration of COD, total nitrogen (TN) and total phosphorus (TP) was observed in filtrate, which should be treated before recirculation of filtrate to biological wastewater treatment plant. This study was focused on removal of nitrogen and phosphorus contained in the filtrate of ATAD, using struvite crystallization method. The effect of operational and environmental parameters (such as, N, P and Mg ion concentration and molar ratio, pH, reaction time, agitation strength, seed dosage, and reaction temperature) on the treatment of TN and TP with struvite crystallization were evaluated. Magnesium (as $MgCl_26H_2O$) and phosphorus (as $K_2HPO_4$) ions were, if necessary, added to increase nitrogen removal efficiency by the crystal formation. Average concentration of $NH_4^+-N$ and $PO_4^{3-}-P$ of the filtrate were 1716.5 mg/L and 325.5 mg/L, respectively. Relationship between removal efficiencies of nitrogen and phosphorus and molar ratios of $Mg^{2+}$ and $PO_4^{3-}-P$ to $NH_4^+-N$ was examined. Crystal formation and nitrogen removal efficiencies were significantly increased as increasing molar ratios of magnesium and phosphorus to nitrogen. As molar ratio of $Mg^{2+}:PO_4^{3-}-P:NH_4^+-N$ were maintained to 2 : 1 : 1 and 2 : 2 : 1, removal efficiencies of nitrogen and phosphorus were 71.6% and 99.9%, and 93.8% and 98.6%, respectively. However, the effect of reaction time, mixing intensity, seed dose and temperature on the struvite crystallization reaction was not significant, comparing to those of molar ratios. Settled sludge volume after struvite crystallization was observed to be reduced with increase of seed dose and to be increased at high temperature.

• Korean Journal of Ecology and Environment
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• v.55 no.1
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• pp.1-9
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• 2022

An estuary is an area where a freshwater river or stream meets the ocean. Even before the importance of the value of estuaries was recognized, the estuary was lost because of large-scale conversion by draining, filling, damming, and dredging. In South Korea, 643 estuaries are located, and the total area is 3,248,300 ha, accounting for 32.5% of the total area of South Korea. Over 35% of Korean estuaries are closed estuaries which are only temporally connected with the sea, either permanently or periodically. Since 2008, in order to preserve the estuary ecosystem and solve major issues in the estuary by accumulating knowledge about the estuarine ecosystem, the Ministry of Environment of Republic of Korea has been conducting the "Estuarine Ecosystem Monitoring and Assessment Project". At 668 sites of 325 estuaries, epilithic diatom, benthic macroinvertebrate, fish, and vegetation are investigated, and the habitat condition of each site is evaluated using the newly developed biotic index. More than 100 researchers annually record 2,097 species of estuaries according to the standardized survey guidelines over the past 14 years and provide strictly managed data necessary for establishing estuaries conservation policies. As a result of bibliometric analysis of 1,195 research articles related to the monitoring and assessment of the estuarine ecosystem, research on pollutants such as heavy metals and sediment control have recently been conducted. "Estuarine Ecosystem Monitoring and Assessment Project" is an ecological monitoring type of long-term mandated monitoring that is usually focused on identifying trends. Although it is difficult to identify the mechanism influencing a change in an ecosystem through long-term mandated monitoring, providing empirical data for supporting evidence-based policy, decision-making, and the management of ecosystems. In order to increase the efficiency of the project, research to investigate the relationship between sediments and pollutants and organisms can be conducted at specific estuaries or sites to compensate for the shortcomings of mandatory monitoring.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.28 no.4
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• pp.457-468
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• 1995

In order to develop a more practical culture system from the present running seawater tank system, two experiments of environmental factors, growth, survival rate and rearing density of olive flounder (Paralichthys olivaceus) were carried out for two consecutive years. Two groups of fish in initially averaging 7.5cm of total length, and 3.4g of body weight (EXP. I) and 5.0cm and 1.8g (EXP. II) were reared in the semi-closed recirculating seawater system equipped with the rotating biological contactors with the commercial culture scale. The dissolved inorganic nitrogen concentrations is EXP. I ranged 0,247-0.512 ppm of $NH_4-N$ (0.010-0.043 ppm of$NO_2-N$, and 0.108-0.342 ppm of $NO_3-N$, and those in EXP. II were 0.091-0.715 ppm, 0.002-0.045 ppm, and 0.007-0.277 ppm, respectively. Daily feeding rates of the fish were $0.67-2.41\%$ in EXP. I and $0.69-2.22\%$ in EXP_ II, and teed efficiency were $34.8-59.8\%\;and\;40.5-88.4\%$ in EXP. I and II, respectively. The average total ten說h and body weight were 40.0-42.8cm and 695.0-852.69g after 340 days culture in EXP. I, and 36.7-39.7cm and 552.4-706.4 g after 365 days culture in EXP. II, respectively. Survival rates of the fish at the end of EXP. I and II were $92.0\%\;and\;96.0\%,$ respectively. The ratio to body surface area of non-ocular side in all fish to bottom area of rearing tank, so-called covering rate, was used as an indicator of rearing density. The highest cowering rate and weight density of fish per $m^2$ of rearing tank at the end of experimental period were 2.2 and 34.1kg in EXP. I, and 2.6 and 36.3kg in EXP. II, respectively. For the commercial culture of olive flounder, the semi-closed recirculating seawater system was found to be more effective than the running seawater tank system in aspect to the fish productivity and protection of marine environment.

• Korean Journal of Environmental Agriculture
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• v.27 no.3
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• pp.217-224
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• 2008

To obtain optimum configuration, depth and load of constructed wetlands(CWs) for treating of hydroponic waste solution(HWS) which was produced in greenhouses, the study was conducted with 4 kinds of combined systems such as Vertical flow(VF)-Horizontal flow(HF), VF-VF, HF-VF and HF-HF CWs. In four configurations of CWs, the treatment efficiency of pollutants from HWS under depth of HF and VF beds, HWS loading and HWSs were investigated. Removal rate of pollutants under different depth of VF and HF in 2-stage hybrid CWs was in the order of 50 cm < 70 cm regardless of CWs configuration. Removal rate of pollutants under HWS loading in 2-stage hybrid CWs was in the order of $150L\;m^{-2}\;day^{-1}{\fallingdotseq}300L\;m^{-2}\;day^{-1}\;>\;450L\;m^{-2}\;day^{-1}$. The optimum depth and HWS loading were 70 cm and $300L\;m^{-2}\;day^{-1}$ in four configurations of CWs, respectively. Using this optimum condition, for various HWSs (cucumber, paprika and strawberry HWS), removal rate of pollutants in HF-HF CWs was higher than that in HF-VF CWs. Optimum configuration of 2-stage hybrid CWs for treating hydroponic waste solution in greenhouses was found out to be HF-HF CWs. Therefore, under the optimum conditions, removal rate of BOD, COD, SS, T-N and T-P in HF-HF CWs were 84, 81, 84, 51 and 93%, respectively.

• Journal of Korean Society of Forest Science
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• v.109 no.1
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• pp.41-49
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• 2020

In this study, the effect of seed pre-treatments and pellet coating materials to enhance the efficiency of large-scale propagation of Aster koraiensis seeds were investigated. Seeds were immersed in water for one day, and only those that sank were used for pre-treatment to use filled seeds. Pre-treatments were divided into hormone treatments, with gibberellic acid (GA₃; 200 and 500 ppm) and 24-epibrassinolide (10^-6, 10^-7, and 10^-8M), and priming with potassium nitrate (100 mM of KNO₃). To produce pellet-coated seeds, pellet materials (DTCS or DTK) were applied to control (unprimed) and primed seeds with binders (PVA or CMC). The maximum germination percent (GP) of seeds before pellet coating was 65% (with the priming treatment), and there was no difference in the GP of seeds among hormone treatments. For seeds sown in a growth chamber on filter paper, GP was 41% for control (unprimed/uncoated) seeds, 65% for uncoated primed seeds, 71% for DTCS/PVA-pellet-coated seeds, and 42% for DTK/CMC-pellet-coated seeds. Seeds that were primed first and then pellet-coated showed greatly improved GP, mean germination time (MGT), and germination rate than seeds that were only pellet-coated. For seeds sown in commercial soil in a greenhouse, control seeds had a GP of 27%, whereas primed seeds had the highest GP (58%), and their MGT and GT were 9.4 days and 7.0%·day, respectively. In addition, DTK/PVA-pellet-coated seeds (40%) also had a GP higher than the control (27%), and their MGT was 15-27 days. For seeds sown in sandy-loam soil in a greenhouse, unprimed-pellet-coated seeds and primed-pellet-coated seeds both had GPs ranged of 39%, which were lower than that of control seeds. In general, the seeds that were pellet-coated with DTK had a higher GP than those pellet-coated with DTCS. Furthermore, the MGT of unprimed-pellet-coated seeds was 15.0-19.8 days, which was longer than the MGT of primed-pellet-coated seeds. These results suggest that priming enhances seedling emergence of Aster koraiensis seeds. Moreover, when priming is combined with pellet coating, DTK is a more suitable pellet material than DTCS, and PVA and CMC are equally suitable adhesives.

• Asian Journal of Business Environment
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• v.2 no.1
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• pp.25-34
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• 2012

It is possible to use pallet for forwarding as chinese cabbages and radishes are general large-scale trading items at the agricultural wholesale market though, however, most of these are forwarded as it have packed in net bags or in P·E bags. Thus, it is still hard for palletizing. The type of packing the product in the net bag makes it difficult for palletizing. It is not a stable shape enough and easily collapsed for pallet loading. Because of this collapsibility, the corrugated cardboard box is being used to enhance forwarding efficiency, but the existing corrugated cardboard box could be crushed easily by moist what is from the agricultural product's property and it also could be squashed by the mass of the loaded box layers on itself. In contrary, the functional waterproof corrugated cardboard box is not collapsed through palletizing and it is efficient for product management with it's ventilation function in respond to pre-cooling effect. Furthermore, because it has various functional shapes as the open type, the partition type and so on, it is effective for maintaining freshness of the product and standardizing the distribution of agricultural product. It is well-known that it is possible to introduce this box to cargo-works of agricultural product. Consequently, the recognition of main distributors about the pallet distribution of the chinese cabbage and the radish was apprehended in this study for activating mechanization of loading and unloading. The survey was conducted to the main distributors such as the forwarder, the auction dealer and the commission merchant with Garak-dong wholesale market as the center. The appropriate packing materials and problems of the existing method for loading and unloading were derived through the survey. Especially, it was focused on analyzing the difference of recognition between the subject groups for the way of using waterproof cardboard corrugated box to deal with the difficult product for packing in normal corrugated box because of the box's absorption of moist from the agricultural product like a chinese cabbage and a radish. Total In the cases of the forwarders and the commission merchants, the net was highly responded as 45%, 74% from each groups for the best packing material for mechanization of distribution and the waterproof corrugated cardboard box was responded as 20%, 22% from each groups as much preferable than multi-stage wooden box. However, for the radish, the waterproof corrugated cardboard box was the best material as 56%, and the auction trader group supported it for 80%. So, the using the waterproof corrugated cardboard box for mechanization of distribution was negative for the chinese cabbage, but it was positive for the radish. The average was 2.42, the standard deviation was 1.24. The negative response(about 55%) was prevailing more than positive response(about 23%). It could be analyzed that even there was the positive recognition for using the waterproof corrugated cardboard box for the radish though the preference for low price of net bag in the chinese cabbage forwarding procedure. Still now, it seems that is a burden for using the waterproof corrugated cardboard box with high price. In the analysis on the recognition differences about using the waterproof corrugated cardboard box for the chinese cabbages and the radish between the forwarders and the commission merchants, generally the negative recognition was prevailing, but the forwarders(2.696) were more positive for using the waterproof corrugated cardboard box than the commission merchants(2.145).

• Korean Journal of Environmental Agriculture
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• v.18 no.3
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• pp.280-286
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• 1999

This studies were conducted to evaluate efficiency of microbial inoculator for active composting of food wastes. The Microbial inoculators used in this studies were purchased from different comparise to evaluate their effectiveness for composting of food waste in Korea. The number of bacteria growing at $30^{\circ}C$ in commercial inoculator collected were below $91.0{\times}10^8\;CFU/g$ which were counted from well cured compost made by animal manure. The number of bacteria in commercial microbial inoculator, such as FL, VP, B9, CM and GE were higher than that of composted at $50^{\circ}C$ or $60^{\circ}C$ of incubation temperature. Fungi were counted in GR, VP and B9 as over $10^3CFU/g$ at $30^{\circ}C$ of incubation temperature, while fungi of all the commercial inoculator collected could not grown at $50^{\circ}C$ and $60^{\circ}C$. Actinomycetes in most of the these had higher number($10^5CFU/g$) than that of compost : however, it was not detected at $60^{\circ}C$ incubation temperature from all the samples collected. The amount of carbon dioxid production was order to VP>HU>B9>GE>CM>Control>Compost in the lab scale composting test with or without inoculation of commercial inoculators, however, but the difference in carbon dioxide production was similar among each treatments. The effect of inoculation on composting parmeter such as pH changes, temperature increasing and change of chemicals properties were a little among each treatments, with or without inoculation of commercial inoculator in active composting of food waste. Using commercial inoculator did not show any statistical difference in food waste composting process under various condition such as pH changes, temperature changes, etc.

• Journal of Animal Environmental Science
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• v.15 no.2
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• pp.171-182
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• 2009

Conventionally, many pig producers have utilized a continual sow managements system that the matings, farrowings and weanings are done weekly basis. But this transitional method is not able to cut the cycle of diseases and fully apply all-in/all-out system because of the continuous flow of sows and pigs. Conventional weekly management system is currently limiting in small farm to work efficiently both for workers and pigs. Therefore, pig producers have found novel management methods for applying all-in/all-out system, improving pig health, leading to better growth, lowering mortality and reducing medication costs nowadays. Moreover, all-in/all-out pig management system has known as a strategy for improving productivity in swine farm. The batch system is one of the best management methods to adopt all-in/all-out pig management system that prevent spreading diseases in pig and remove cycle of diseases. Batch farrowing system is a concept for providing a group of sows that delivery within a specific farrowing interval and inducing a large enough scale of piglets to fill the weaner facilities. There are different types of batch farrowing system with batch size and interval of farrowing when several factors at the swine farm are considered such as total number of sows, available facilities in the farm, and the efficiency of workforce. Sow managements such as farrowing, weaning and breeding, every 3 weeks rather than weekly, 2 or 5-week interval have advantages for workers and reproductive cycle of sows as well as pig flow. Because there are several pros and cons both in weekly and batch management system, various factors should be considered to apply the most suitable management system in each individual farm. To improve poor swine productivity in Korea compared to ED, batch system for sows will be an alternative choice which is able to prevent high incidence of diseases in swine farm such as PMWS, PRRS, PRDC and PED because all-in/all-out pig management can be also applied automatically by using this management system.

• Journal of Korean Society of Forest Science
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• v.77 no.1
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• pp.92-99
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• 1988

The dark respiration, photosynthesis($CO_2$ refixation), $CO_2$ balance and chlorophyll content of 1st-year conelets and 2nd-year cones of Korean pine(Pinus koraiensis S.et.Z.) were investigated after pollination up to the end of maturation. The results obtained are as follows : 1. The growth of 1st-year conelet was 3.6cm in length. 2.4cm in diameter and 3.058 in dry weighs during the first year. The growth of 2nd-year mature cone was 13.5cm in length, 9.3cm in diameter and 141.0g in dry weight in the late of 2nd-year. 2. The refixation of carbon dioxide released from a cone by the dark respiration was less than 50 percent at light saturation through the growing period. The refixation of carbon dioxide released by dark respiration for one year was 7.3 percent in 1st-year conelets and 8.7 percent in 2nd-year cones. 3. The dark respiration rate of cones by increasing temperature was rapidly increased with increasing temperature up to $25^{\circ}C$. The dark respiration rate of cones was much higher in non-growing season than that in growing season at the same temperature. 4. The rates of dark respiration and $CO_2$ refixation, based on the dry weight, were much higher in 1st-year conelet than that in 2nd-year cone. 5. The $CO_2$ balance for a cone was negative from pollination to the end of maturation. The net dark respiration loss for a cone was 7.23g $CO_2$/year in 1st-year conelet and 164.8g $CO_2$/year in 2nd-year cone. 6. The respiratory loss efficiency for a cone(=$CH_2O$ weight calculated by net dark respiration/dry weight of cone) for one year was 1.61 in 1st-year conelet and 0.81 in 2nd-year cone for one year. 7. The total chlorophyll content of surface scale of the cone was lower than 2mg/g dw through the growing period, and chl. a/b ratio was 2 to 3.

• Korean Journal of Ecology and Environment
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• v.47 no.1
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• pp.13-23
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• 2014

To obtain optimum filter media, configuration method and greenhouse wastewater loading in small-scale constructed wetlands (CWs) for treating greenhouse wastewater, the apparatuses were constructed with 4 kinds of combined systems such as vertical flow (VH)-Horizontal flow (HF), HF-VH, HF-VF-HF, VF-HF-HF CWs. The efficiencies of pollutants in greenhouse wastewater were investigated in various CWs under different filter media, configuration methods and agricultural water loading. Removal rates of pollutants under different filter media were in the other of coarse sand>broken stone${\fallingdotseq}$calcite${\fallingdotseq}$mixed filter media for COD, broken stone>mixed filter media>coarse sand>calcite for T-N, and calcite>mixed filter media>broken stone>coarse sand for T-P. The removal rates of pollutants in HF-VH-HF CWs at different configuration methods were higher than those in other configuration methods. The removal rates of pollutants were higher in the order of $150L\;m^{-2}day^{-1}{\fallingdotseq}300L\;m^{-2}day^{-1}$ > $600L\;m^{-2}day^{-1}$ under different greenhouse wastewater loading. Therefore, optimum configuration method was HF-VH-HF CWs, the optimum filter media was mixed filter media (coarse sand : broken stone : calcite=1 : 1 : 1), and the optimum greenhouse wastewater loading was $300L\;m^{-2}day^{-1}$ in HF-VH-HF CWs.