• Journal of Wetlands Research
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• v.21 no.2
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• pp.147-151
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• 2019

Recently, rural areas are rapidly developing, while existing infrastructure is inadequate and aging compared to developing rural areas. The most representative of these is the sewer system. Therefore, in this study, the rural area of Gyeonggi A city was selected as the study area and analyzed the effect of the sewer maintenance business on the operation of the sewage treatment plant. The analysis items were pollutant treatment efficiencies, the changes of inflow sewage amount, sewage concentration, influnet load, and C / N ratio by comparing before and after the development. As a result of the analysis, the sewage amount increased significantly after the development, and the sewage concentration increased after the development and the load of the sewage in the wastewater treatment plant also increased after the development. And improvement and management of inflow of unidentified water such as infiltration water and influent water in the sewage pipe was improved due to improvement of sewage pipe, which is considered to have affected the increase of C / N ratio and the improvement of TN and TP removal efficiency. The results of this study can be used as a representative example of the sewerage maintenance project in the rural area that positively influenced the operation of the sewage.

• Journal of the Korea Organic Resources Recycling Association
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• v.7 no.2
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• pp.47-55
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• 1999

Recently, the treatment of that wastes according to increase of food waste has been a great problem of modern society for long time. This study was aimed to evaluate possibility for food waste and sewage sludge mixture treatment using pilot scale two-phase anaerobic digester. Pilot scale two-phase anaerobic digestion system was performanced at 1 : 9 mixture ratio of food waste and sewage sludge infield. The detention time of digester was 20days. The average COD and VS removal efficiencies in organic loading rate $3.03kg\;TCOD/m^3-day$ were 57.7 and 47.7%, and the gas production rate and methane content were $0.4m^3/kg$ VS-day and 65.3%, respectively. TS, VS and VS/TS(%) of mixing tank were 4.44%, 2.59% and 58.34%, respectively and TS. VS and VS/TS(%) of digester in steady state were 3.32%, 1.39% and 41.90%, respectively, Through this study. it was possible to accomplish effective mixture treatment of the sewage sludge and food waste.

• Resources Recycling
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• v.26 no.2
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• pp.33-38
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• 2017

Waste can be utilized as secondary or alternative fuel. Solid recovered fuel (SRF) and dried sewage sludge were combusted to investigate heavy metal emissions from their combusiton in this study. Content of copper (Cu), chromium (Cr), cadmium (Cd), nickel (Ni), zinc (Zn), lead (Pb), arsenic (As) and mercury (Hg) of coal, SRF and dried sewage sludge were determined, respectively. Concentrations of these heavy metals in the combustion flue gas were also determined. As a result, emissions of gas-phase Cu, Cr, Cd, Ni, Zn, Pb and As compounds were found to be little. However, a significant amount of gas-phase Hg was emitted from combustion of coal, SRF and dried sewage sludge. While SRF showed a high mercury oxidation percentage in its combustion flue gas, dried sewage sludge showed a high level of gaseous mercury emission.

• Journal of Korean Society on Water Environment
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• v.36 no.6
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• pp.535-545
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• 2020

This study aims to conserve and monitor energy use in public sewage treatment plants by utilizing data from the SCADA system and by controlling the aeration rate required for maintaining effluent water quality. Power consumption in the sewage treatment process was predicted using the equipment's uptime, efficiency, and inherent power consumption. The predicted energy consumption was calibrated by measured data. Additionally, energy efficiency indicators were proposed based on statistical data for energy use, capacity, and effluent quality. In one case study, a sewage treatment plant operated via the SBR process used ~30% of energy consumed in maintaining the bioreactors and treated water tanks (included decanting pump and cleaning systems). Energy consumption analysis with the K-ECO Tool-kit was conducted for unit processing. The results showed that about 58.7% of total energy consumed was used in the preliminary and biological treatment rotating equipment such as the blower and pump. In addition, the energy consumption rate was higher to the order of 19.2% in the phosphorus removal process, 16.0% during sludge treatment, and 6.1% during disinfection and discharge. In terms of equipment energy usage, feeding and decanting pumps accounted for 40% of total energy consumed following 27% for blowers. By controlling the aeration rate based on the proposed feedback control system, the DO concentration was reduced by 56% compared pre-controls and the aeration amount decreased by 28%. The overall power consumption of the plant was reduced by 6% via aeration control.

• 수도
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• s.15
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• pp.13-24
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• 1978

• Korean Journal of Environmental Agriculture
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• v.18 no.3
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• pp.236-244
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• 1999

A feasibility study was performed to examine the agronomic application of treated sewage on paddy rice culture by field experiment. The domestic sewage was treated by the constructed wetland system which was in subsurface flow type and consisted of sand and macrophyte. The effluent of the wetland system was adjusted to maintain the total nitrogen concentration below $25mgL^{-1}$ and used for irrigation water. Four treatments include (1) irrigation of treated sewage after concentration adjusted with conventional fertilization (TWCF), (2) irrigation of treated sewage after concentration adjusted with half of the conventional fertilization (TWHF), (3) irrigation of treated sewage after concentration adjusted without fertilization (TWNF), and (4) irrigation of treated sewage as it was without fertilization (SWNF). These cases were compared to the control case of tap water irrigation with conventional fertilization (Control). Generally, addition of the treated sewage to the irrigation water showed no adverse affect on paddy rice culture, and even improvement was noticed in both growth and yields. TWCF showed the best result and the yields exceed the Control in about 10%. Overall performance of the treatments was TWCF, Control, TWHF, TWNF, and SWNF in decreasing order. From this study, it appears that reuse of treated sewage as a supplemental irrigation water could be feasible and practical alternative for ultimate sewage disposal which often causes water quality problem to the receiving water body. For full scale application, further study is recommended on the specific guidelines of major water quality components and public health.

• Journal of Environmental Science International
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• v.5 no.1
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• pp.61-69
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• 1996

The combined wastewater of municipal landfill leachate and municipal sewage was treated using several sets of bench-scale aerated circulating system including porous media. Investigated items in this experiment were the dominant protozoa and metazoa in this system, the variation of microfauna relationship between operating condition and dominant genera. Also considered the factors determining dominant genera and their role. The outcome of this research is as follows; 1. Aspidisca, Vorticella, Truhellophyllum, Lecane, Philodina, Cyclops were mainly appeared prior to combinding leachate, while Trachelocerca, Bodo, Glaucoma were the dominant genera after combinding leachate. 2. As to metazoa, Nematode and Philodina were not influenced by 5oA leachate mixing ratio, meanwhile Crustacea has high sensitivity for increased leachate mixing ratio and it was not appeared in 5% leachate mixing ratio. 3. The appropriate treatability could'nt be expected at the above 10% leachate mixing ratio. Especially, in the condition of 20% leachate mixing ratio, all of the microfauna were affected damage seriously on their existence. Meanwhile hydraulic retention time, substrate loading rate and slut자e production rate didn't give notable influence on increasing the number of microfauna. 4. As to protozoa, saprozoic and holozoic species were appeared commonly and polysaprobic species were dominent. 5. Filamentous organsms were nearly not affected by leachate mixing. It seems that they could live without any trouble at the 10% leachate mixing ratio, if the substrate is sufficient. 6. Diversity of microfauna had a reducing trernd as the sewage was mixed with leachate.

• Journal of Digital Convergence
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• v.10 no.10
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• pp.221-227
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• 2012

In Korea, ocean dumping has been widely used as the ultimate disposal of sewage sludge. However, ocean dumping of food wasted and sewage sludge from 2013 is expected to legally restricted as London convention on marine pollution prevention has been effective in 2009. This research aims to examine the effect of HEAS in treating the environmental pollution load caused by organic high concentrated sludge. Thus, onsite laboratory scale treatability test using HEAS was adopted to treat the high concentrated organic sludge from sewage and industrial wastewater treatment plant. The research results showed that the HEAS is useful to reduce the environmental pollution caused by organic high concentrated sludge. Specific results are as follows. 1. The organic removal after the sludge digestion using the high efficiency aeration system was 55.2-85.8%. Although these results were lower than those from the general sewage treatment, the high efficiency aeration system could be evaluated as efficient, considering the object sludge contained the industrial waster water. 2. The average removal efficiency was about 25.2%. 3. It was revealed that sludge digestion by the high efficiency aeration system could effectively contribute to the sludge treatment cost. Especially, the high efficiency aeration system is more applicable to the onsite treatment of small sewage and wastewater treatment plant that contains high solid content sludge, industrial wastewater sludge, high fixed solid sludge.

• Journal of Ecology and Environment
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• v.41 no.11
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• pp.318-327
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• 2017

Background: A typical sewage treatment plant is designed for organic and nutrient removal from municipal sewage water and not targeted to eliminate micropollutants such as pesticides, pharmaceuticals, and nano-sized metals which become a big concern for sustainable human and ecological system and are mainly discharged from sewage treatment plant. Therefore, despite contaminant removal by wastewater treatment processes, there are still remaining environmental risks by untreated pollutants in STP (sewage treatment plant) effluents. This study performed aquatic toxicity tests of raw wastewater and treated effluents in two sewage treatment plants to evaluate toxicity reduction by wastewater treatment process and analyze concentration of contaminants to reveal potential toxic factors in STP effluents. Methods: Water samples were collected from each treatment steps of two STPs, and acute and chronic toxicity tests were conducted following USEPA (United States Environmental Protection Agency) and OECD (Organization for Economic Cooperation and Development) guidelines. Endpoints were immobility for mortality and reproduction effect for estrogenicity. Results: Acute $EC_{50}s$ (median effective concentration) of influents for Seungki (SK) and Jungnang (JN) STPs are $54.13{\pm}32.64%$ and $30.38{\pm}24.96%$, respectively, and reduced to $96.49{\pm}7.84%$ and 100%. Acute toxicity reduction was clearly correlated with SS (suspended solids) concentration because of filter feeding characteristics of test organisms. Chronic toxicity tests revealed that lethal effect was reduced and low concentration of influents showed higher number of neonates. However, toxicity reduction was not related to nutrient removal. Fecundity effect positively increased in treated wastewater compared to that in raw wastewater, and no significant differences were observed compared to the control group in JN final effluent implying potential effects of estrogenic compounds in the STP effluents. Conclusions: Conventional wastewater treatment process reduced some organics and nutritional compounds from wastewater, and it results in toxicity reduction in lethal effect and positive reproductive effect but not showing correlation. Unknown estrogenic compounds could be a reason causing the increase of brood size. This study suggests that pharmaceutical residues and nanoparticles in STP effluents are one of the major micropollutants and underline as one of estrogenic effect factors.

• Journal of Korean Society of Water and Wastewater
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• v.19 no.5
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• pp.557-564
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• 2005

The objective of this study is to evaluate a criteria of intercepting capacity and a reduction goal of overflow pollution load in combined sewer system. In the current criteria of intercepting capacity in the domestic sewage facility standard, it is known that three times of peak sewage (Q) in dry period or runoff flow by 2mm/hr is not appropriate since the intercepted flow is estimated by runoff and show different result even in the same watershed. Though a reduction goal of overflow pollution load can be determined from 1) same level of storm-water runoff pollution load in separated storm sewer, 2) less than 5% sewage load in dry weather period, by the domestic sewage facility standard, the simulated results from storm-water model show large differences between two criteria. While it is predicted that sewage pollution load standard three time larger than separated storm sewer standard in high population density and urbanized area, it is shown that separate storm sewer standard larger than sewage pollution load standard in middle population density and developing area. Accordingly, it is proposed that more reasonable intercepting flow and reduction goal of overflows pollution load should be established to minimize discharging pollution load in combined sewer systems. For the purpose, a resonable standard has to be amended by pollution load balance considering the characteristics of a watershed for generation, collection, treatment, and discharging flow.