• FLOWER RESEARCH JOURNAL
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• v.17 no.1
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• pp.1-8
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• 2009

This study was conducted to investigate the efficiency of water quality remediation and the inorganic ion removal characteristics by floating plant; water lettuce (Pistia stratiotes L.) in a batch reactor. Water lettuce can be used to remove N and P and other inorganic nutrients, by consuming them in the form of plant nutrient. The highest nutrient absorption of water lettuce was $112.5meL^{-1}\;N$ in Sonneveld-2S, $56.6meL^{-1}\;N$ in Sonneveld-1S, $31.8meL^{-1}\;N$ in sewage and P value was also the highest in Sonneveld-2S as $15.6meL^{-1}$ and in sewage as $5.0meL^{-1}$. These results indicated that using water lettuce held some promise in the context of purification of eutrophication. Also water lettuce had a preference for absorption N. Under Sonneveld-2S treatment, nitrogen percentage was the highest in plant tissue due to the highest concentration of nitrogen and removal by water lettuce. Under sewage, percentage of total N in both plant parts was high. Both above and underground parts, P percentage was less than N. It might be due to the fact that the absorption amount of P was less than N by water lettuce. It meaned that the ability of N removal by water lettuce was higher than that of P, relatively. In summary, these results show that the use of this plant was a viable option.

• Journal of Wetlands Research
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• v.15 no.1
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• pp.1-8
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• 2013

A pilot scale coagulation system, which has a function of physicochemical treatment, was developed to treat Combined sewer overflows(CSOs). This coagulation system requires evaluation of optimum design factors whether it has reflected those of lab scale system, moreover, the pilot scale system can be evaluated differently according to the characteristics of influent CSOs even though it has reflected lab scale's design factors. We conducted an experiment using lab scale system that could treat $1m^3$ of CSOs in a day, and also pilot-scale system with $100m^3/day$ CSOs flowed into the Cheongju sewage treatment plant. Therefore the aim of this study is to evaluate a hydraulic similarity between the design factors of pilot scale and those of lab scale coagulation system, and to evaluate feasibility of the coagulation system for the CSOs treatment with optimum operation conditions. From the result of pilot-test, we drew the optimum operation factors of in line mixer and flocculator having similarities with those of lab scale system as well as the optimum coagulant dose. Finally we confirmed that the coagulation system has feasibility to treat the CSOs with high removal efficiency.

• Journal of the Korea Organic Resources Recycling Association
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• v.6 no.2
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• pp.45-57
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• 1998

The object of this experiment was to determine the optimum mixing ratio of paper mill sludge and sewage sludge with woodchips as a bulking agent. The bulking agent was mixed with the mixture of paper mill sludge and sewage sludge(2:1 by dried weight) at the rates of 0(W-0), 20(W-20), 33(W-33), and 50(W-50)% on volume basis, and then the mixtures were composted by forced aerated static pile. The changes of physicochemical properties of the mixtures were measured during the composting in order to evaluate the maturity of composts. The temperatures of W-30 and W-50 treatments increased rapidly as soon as the composting started, and reached $60^{\circ}C$ in the fifth day of composting. Reduction of hot water soluble C/N ratio of W-33 and W-50 treatments showed faster than that of W-0 and W-20 treatments at early stage of the composting. The contents of hot water soluble $NO_3{^-}-N$ showed little change in the early stage of the composting in all treatments, but increased rapidly after 20 days of the composting, and the contents of W-0 among all treatments were lower than the others. The G.I. values of W-50 treatment were over 80 before 20 days after starting the composting, those of W-0 treatment were over 80 after 30 days. As a result of evaluation of compost, W-33 and W-50 treatments were found very reasonable at the mixing ratio of a bulking agent. But it is very difficult to aerate compost pile for W-50 treatment than W-33 treatment due to intensified fluctuation of temperature. Considering cost, availability of a bulking agent, and productivity of compost, W-33 treatments more efficient than W-50 treatment.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.110.2-110.2
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• 2011

바이오가스 생산은 현재 정부에서 추진하고 있는 저탄소 녹색성장으로 인해 더욱 그 가치의 중요성이 부각되고 있다. 스웨덴 Scandinavian Biogas Fuel AB(SBF) 사의 바이오 가스 생산 기술을 이용함으로 소화효율을 개선하고 바이오가스 발생량을 극대화하였다. 전국 403개 공공하수처리시설 중 소화조가 설치된 처리시설은 65 개소이며 이중 57 개소에서 총 64개 소화조를 운영 중이다. 하지만 국내 소화조의 효율은 유입수질 저하, 운영, 관리 미숙으로 인해 전진국의 1/4 수준으로 에너지 이용률이 미미한 편이다. 환경부는 2010년부터 에너지 이용, 생산사용 확대, 추진을 위해 하수처리시설별 이용 가능한 에너지 잠재력의 종류, 양, 지역 내 수요자, 공급자 의 현황 규모 등을 정리해 2012년부터 에너지 이용사업 확대를 추진한다. SBF의 기술을 바탕으로 하수처리시설에서 들어오는 하루 슬러지 $1370m^3$와 음식물쓰레기 180t을 함께 처리하며 바이오가스 생산량을 더욱 늘렸다. 각 $7,000m^3$의 달걀모양(egg shape) 소화조 2개를 운영하며 생 슬러지와 음식물 쓰레기 처리 후 바로 소화조로 투입, 혐기 소화하는 방식이며 슬러지 최종처분방법은 탈수 후 소각된다. 반입되는 생 슬러지의 평균 TS 1.7%, VS 63% 이며 농축 후에는 평균 TS 9%, VS 75% 이다. 또 소화조로 들어가는 음식물 쓰레기는 평균 TS 8%, VS 85% 이며 소화 후 평균 TS 3.6% VS 59% 이다. 그리고 소화조의 pH는 7.3~7.8,유기산의 농도는 150mg/L~350mg/L, 가스발생량은 하루 평균 $26,500Nm^3$이며 소화효율은 평균 67%이다. 혐기성소화는 산소가 없는 무 산소 상태 에서 분해 가능한 유기물을 분해시켜 메탄으로 전환시키고 우리는 현재 이 가스를 소화조 가온에 사용하고, 판매하고 있다. 소화효율을 높이기 위하여 가온과 교반이 행해지는데 가온방식은 직접가온방식(증기주입식)과 간접가온방식(열교환방식)이 있다. 그중 우리는 간접가온방식을 채택하여 소화효율을 높였고 일반중온 혐기소화온도보다 약간 높은 $38^{\circ}C$로 운전한다. 그리고 일반적으로 알려진 교반방식인 가스교반, 기계교반, 이 둘은 병행한 교반이 아닌 독자적인 방법을 이용, 소화조 내의 슬러지가 정체되어 교반되지 않는 부분을 최소화 하였다. 이때 미생물이 투입되기 힘든 소화조 아래 쪽 으로도 고루분포 되어 슬러지를 이용 하게 되고 소화조 상하부의 온도차가 $1^{\circ}C$ 이하로 거의 완벽한 교반상태를 보여 줌 으로써 소화효율을 최대한으로 한다. 더욱이 소화일수 부족으로 인한 전반적 소화효율 저하가 발생하지 않도록 input과 output 조절을 통한 적정소화일수 20~25일을 최대한 맞추어 운전하여 소화조 설계용량의 평균 90%를 활용하고 있다.

• Korean Journal of Ecology and Environment
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• v.35 no.2 s.98
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• pp.133-140
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• 2002

This study was performed in lab scaled oxidation pond. The removal efficiency of pollutant on the influence of changes of hydraulic retention time and pond style was investigated. The correlation between organic removal efficiency and dissolved oxygen concentration on algal photosynthesis showed the light time revealed a higher relationship more than the dark time, and the squares of the correlation coefficient of 15 days retention time were higher than that of 5 days in single pond. The variation of dissolved oxygen concentration of a series pond was from 4.2 to 19.8 mg/l under 5 days retention time, the concentration of dissolved oxygen increased with increasing step of series pond. Between the single pond and a series of pond system, a series of pond system showed better organic removal efficiency. Average removal efficiency range of $TBOD_5$ and $SBOD_5$ was $49{\sim}83%$ and $87{\sim}92%$, respectively. Algae should be removed appropriately to increase the removal efficiency of organic matter.

• Journal of the Korea Organic Resources Recycling Association
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• v.24 no.3
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• pp.35-43
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• 2016

COD properties of waste activated sludge (WAS) were investigated for various solubilization rate of mechanical pretreatment method in anaerobic digestion process. Inert COD was 37.0% of total COD in untreated WAS. Particulate biodegradable COD was converted to soluble biodegradables and particulate unbiodegradables as solubilization was processed. Particulate unbiodegradable portion of COD in WAS can be increased as particulate biodegradable portion is decreased in case of relatively long SRT of biological treatment. Thus, COD properties of WAS should be investigated in case of relatively low particulate biodegradable COD, because of possible low effect of solubilization. COD removal rate in anaerobic digester was enhanced as much as 2.1% and 15.1% for solubilization rate 5% and 35% due to pretreatment, respectively. COD removal rate was increased from 25% to 40%, and methane gas generation was increased from $607m^3/d$ to $907m^3/d$ as particulate COD of WAS was solubilized to 35% in pretreatment facilities.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.9 no.2
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• pp.74-85
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• 1997

Accurate analysis of water budget and seawater exchange characteristics is essential for the improvement and management of the degraded water quality in Masan Bay. In this study, water budget is simulated for the four divided coastal zones on the monthly base, and watershed runoff discharges which are important as input parameters are estimated using the runoff coefficient(=0.7). The main results are as follows : The runoff-contribution rate due to water supply discharge is increased from 10% in 1978 to the equivalent amount at present. The reduction quantity due to the wastewater interception is about 25% of total inflow discharges, and the net effects of both precipitation and evaporation is about 10%. As the hydraulic detention time in Masan Bay is estimated about 3 months, water exchange rate is to be very low. From the analysis of the salinity variation on account of water mixing, it appears no temporal correlation between monthly average precipitation and salinity, whereas only regional correlation is apparent.

• Journal of the Korea Organic Resources Recycling Association
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• v.10 no.3
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• pp.110-116
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• 2002

The aim of this study was to analyze food waste treatment cost and to estimate effect of by-product, such as wastewater and foreign materials, on amount cost. In cost analysis, man power and facility capacity are fixed, whereas operation cost, by-product treatment and et, al. are varied by treatment methods. The rate of by-product treatment cost in amount cost are between 5% and 39%. The methods which consume large electric power or generate much wastewater showed higher rate of by-product treatment cost in range of 14 to 39%. On the other hand, the methods which have simple process showed lower rate in range of 5 to 11%. Thus, this study recommend that by-products should be treated in sewage treatment facilities or landfill sites to prevent illegal disposal of by-products or to reduce burden of by-product from private sectors.

• Journal of the Korean association of regional geographers
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• v.10 no.3
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• pp.568-578
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• 2004

This study is aimed at investigating floodgate characteristics and environmental issues in Gwangjucheon and examining possible problems of expanding river maintenance water being carried on in the context of river recovery works. In general, the obtained results show the following. The treatment water provisioned in the restoration project of the drying stream going through the water circulation device can pollute the land and groundwater in the Gwangjucheon Basin. Besides, although about $17,565m^3$/day of water is available in the upper ground, most of it go to the junction and exhausting directly to the waste water treatment or going into the groundwater. Because of the drying stream, the amount of water going to the ground is increased. Therefore, efficient land use along with regulations to protect cultivated land and ensure recovery works of city stream through the recovery of water circulation by constructing and expanding a special drainage system are of vital importance.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.425-425
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• 2021

북평산업단지내 공공폐수처리시설(6,500톤/일)의 가동률은 30% 이하로 매우 저조하며, 폐수배출업체는 29개소로 그 수가 적어 배출오염부하량 비율에 따른 처리비용이 일부 업체의 경우 과도하게 부과되고 있는 실정이다. 입주업체 운영비용 부담을 저감하기 위해 해당 지자체에서는 운영비용의 65% 이내에서 일정금액을 지원하고 있으나, 동일업종에 대한 원인자비용부담금 비율의 경우, 동해시 A업체는 30.18%로 타 지역 B업체의 4.83% 보다 높은 것으로 나타났으며, 지자체 지원금을 제외한 순수 처리부과금의 경우 A업체가 2배 이상 큰 것으로 나타났다. 이에 북평산업단지 공공폐수처리시설의 전체 운영비 절감을 위한 효율적인 운영방안 마련이 필요하다. 따라서 본 연구에서는 북평산업단지내 공공폐수처리시설의 운영 및 관리현황을 검토하여 효율적인 운영방안을 제시하고자 하였다. 현재 운영시설에 대한 현황을 파악하고 관련 법률 및 계획등을 검토한 결과, 북평산단 지역은 하수처리 구역이 아닌 공공폐수처리구역으로 산업폐수의 공공하수도처리시설 연계처리 지침에 따라 인근 공공하수처리시설과의 연계처리가 불가한 것으로 나타났다. 또한, 환경부에서는 가동률이 저조한 처리시설에 대해서는 시설개선을 통한 방안을 제시하고 있어 현 처리시설의 공정개선을 통한 운영비 절감방안이 가장 효율적인 것으로 판단되었다. 이에, 현재 생물 반응조 후단에서 운영 중인 가압 부상조에 새로운 배관을 설치하여, 최초 침전지 유출수를 가압부상조 처리 후, 생물 반응조로 유입하고, 최종 침전 후 총인을 제어 할 수 있는 약품투입 시설을 설치하는 공정 개선 방안을 제시하였다. 이처럼 생물 반응조 이전에 가압부상조를 설치하고, 후단 가압 부상조 미운영시 공정개선 전·후에 따른 총 슬러지 발생량은 24.2%, 탈수케익 처리비용은 27.6% 절감할 수 있는 것으로 산정되었으며, 전체 처리시설에 대한 총 운영비 감소율은 13.4%로 분석되었다.