• Journal of Korean Society of Water and Wastewater
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• v.27 no.5
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• pp.603-610
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• 2013

According to industrialization, increased toxic chemicals discharge has been causing water pollution. Especially domestic sewage is a major source of water pollution. Sixty percent of the total wastewater discharged is domestic sewage. Self-purification capacity of rivers and streams is drastically reduced by the emission of domestic sewage, industrial wastewater and livestock wastewater. Although domestic sewage is managed by implementing standards and regulations, toxicity effect of domestic sewage to humans and the environment is not yet clearly understood. In this study, by using daphnia magna, the ecotoxicity of domestic swage was assessed. Cl, Cu, Pb, COD, T-N, DO, pH and residual chlorine were investigated as background concentrations. The experiments were conducted with water samples obtained from three local sewage treatment plants. The experiment results indicated that higher level of toxicity corresponds to the higher pollution concentrations. The higher level of combinations of background concentrations such as heavy metals leads to the worse ecotoxicity. Especially, the Cu concentration affects the TU value.

• Journal of Korean Society on Water Environment
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• v.25 no.2
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• pp.268-280
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• 2009

Oncheon basin which are located in Busan is divided into 43 basin on the basis of main pipe, constructed with Storm Water Management Model (SWMM). Occurrence situation for Outflow and pollutant loads by long-term continuous rainfall is examined for treatment district and river analysis point of Oncheon basin and a reduction vs effectiveness table for effective CSOs managements is made for each of treatment districts according to each of managements. In case that treatment equipment is located at the discharge point of CSO, treatment efficiency is analysed. It is supposed that treatment equipment have an efficiency on the basis of a concentration and runoff discharge over a critical flow is discharged with it untreated and treating runoff discharge with treatment equipment at each of runoff discharge points and treating it gathered at sewage treatment plant (STP) through trunk sewer is compared for a relative treatment efficiency.

• Journal of Korean Society on Water Environment
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• v.26 no.5
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• pp.871-879
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• 2010

To figure out the removal efficiency of indicator and pathogenic bacteria by unit processes of a sewage treatment plant using activated sludge process, analyses were done for incoming sewage, influent and effluent of primary clarifier, aeration tank, secondary clarifier and final discharge conduit of the plant. A matrix of bacterial items (average of bacterial reduction [log/ml], p value of paired t-test, number of decreased cases of twenty analyses, removal percentage only for decreased cases) between incoming sewage and final effluent of the plant were heterotrophic plate counts (1.54, 0.000, 20, 95.01), total coliforms (1.38, 0.000, 19, 83.94), fecal coliforms (0.90, 0.000, 20, 94.84), fecal streptococci (0.90, 0.000, 20, 98.08), presumptive Salmonella (0.23, 0.561, 7, 99.09), and presumptive Shigella (1.02, 0.002, 15, 92.98). Total coliforms, fecal coliforms, heterotrophic plate counts, and fecal streptococci showed highest decrease through secondary clarifier about 1-log (p<0.001) between 88% and 96%, and primary clarifier represented the significant (p<0.05) decrease. However, final effluent through discharge conduit showed higher total coliforms and fecal streptococci than effluent of secondary clarifier (p<0.05). In addition, final effluent once violated the water quality standard while effluent of secondary clarifier satisfied the standard. Hence some control measures including elimination of deposits in discharge conduit or disinfection of final effluent are necessary.

• Journal of Korean Society of Water and Wastewater
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• v.19 no.4
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• pp.462-472
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• 2005

This study was carried out to suggest the plans for installation of rural sewage treatment facilities through the analysis of these facilities installed in Chungchongnam-do Province. About 5% of all installation was carried out by the department of wastewater and related environment problems and the other case was carried out by the department of construction or residence. In wastewater caused by 250 and 300 persons, facilities capacity do not exceed about $50m^3/d$, caused by 2,500 and 3,000 persons, $500m^3/d$. Advanced sewage treatment process were first needed in the discharge area where affected the water environment greatly. However, in carrying out the water quality pollutant of the total amount management system in the other areas, they should be driven only over the scale of pollutant quota object facilities standard. Rural sewage must be included in the special accounts according to the regulations of local government, and sewage treatment cost should be collected to manage. Installation type uses integrating joint treatment method in case the distance among villages is short or one treatment facility independently.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.40 no.1
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• pp.127-133
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• 2020

Most sewage treatment plants located offshore are discharged to the shore either directly or through rivers. Therefore, the water quality of the treated water discharged from the sewage treatment plant affects the water quality of the river water discharged to the river and the ocean. In this study, field surveys and numerical simulations were conducted to investigate the effect of treated water from the sewage treatment plant adjacent to the coastal environment. As a result of analyzing the water quality and sediment quality with the samples collected from the river and the estuary where the treated water was discharged to understand the impact on the coast, the treated water discharged from the sewage treatment plant was discharged to the river without exceeding the design criteria. However, the water quality discharged to the shore through estuaries was more contaminated than treated water. The cause of water quality deterioration of coastal effluent is due to the sedimentation of estuary temporarily by longshore sediment sransport which appeared around the estuary, the occurrence of estuary obstruction, and the increase of stagnant time in the estuary. As it was released and discharged, it was analyzed to affect the water quality, water quality and marine life around the estuary. Therefore, in the case of the east coast where the longshore sediment transport is strong, when planning the sewage treatment facility discharged to the ocean, it is necessary to closely examine the water quality change of the river water in the treated water such as the river mouth occlusion by the longshore sediment transport.

• Journal of Environmental Science International
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• v.23 no.10
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• pp.1755-1762
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• 2014

Water quality of the Koejong-reservoir was estimated by using the ecological model to evaluate the effects of industrial sewage discharge. State variables consist of POC, DOC, phytoplankton, DIP, DIN, DO and COD. Initial conditions for the compartment are applied to the model based on the observed results. The reproducibility was found to be satisfactory with the relative error ranging between the calculated value and the observed value. Water quality simulation was conducted by applying additional industrial sewage discharge into the Koejong-reservoir. The concentrations of COD, Chl.a, DIP and COD showed fluctuations of a narrow range. The increment percentages of Chl.a, COD and DIP were 26.6%, 20.2% and 18.2%, respectively. In the case of DO, the concentration decreased 4.8%.

• Journal of Soil and Groundwater Environment
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• v.17 no.2
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• pp.37-46
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• 2012

This study was conducted to identify groundwater recharge and discharge amounts of a representative urban-rural composite area located in Yongin city, Kyounggi-do, Korea. Groundwater recharge would be affected by mainly two processes in the study area: rainfall and leakage from public water pipelines including water-supply and sewage system. Groundwater recharge rate was estimated to be 13.5% by applying annual groundwater level data from two National Groundwater Monitoring Stations to the master regression curve method. Subsequently, the recharge amounts were determined to be $13,253{\times}10^3m^3/yr$. Leakage amounts from water-supply and sewage system were estimated to be $3,218{\times}10^3$ and $5,696{\times}10^3m^3/yr$, respectively. On the whole, a total of the recharge amounts was $22,167{\times}10^3m^3/yr$, of which 60% covers rainfall recharge and 40% pipeline leakage. Groundwater discharge occurred through three processes in the composite area: baseflow, well pumping, and discharge from urban infrastructure including groundwater infiltration into sewage pipeline and artificial extraction of groundwater to protect underground facilities from submergence. Discharge amounts by baseflow flowing to the Kiheung agricultural reservoir and well pumping were estimated to be $382{\times}10^3$ and $1,323{\times}10^3m^3/yr$, respectively. Occurrence of groundwater infiltration into sewage pipeline was rarely identified. Groundwater extraction amounts from the Bundang subway line as an underground facility were identified as $714{\times}10^3m^3/yr$. Overall, a total of the discharge amounts was determined to be $2,419{\times}10^3m^3/yr$, which was contributed by 29% of artificial discharge. Even though groundwater budget of the composite area was identified to be a surplus, it should be managed for a sound groundwater environment by changing deteriorated pipelines and controlling artificial discharge amounts.

• Journal of Environmental Science International
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• v.25 no.2
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• pp.323-329
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• 2016

In this study, the applicability of MBR process was evaluated to improve processing of personal sewage treatment facilities of $50m^3/day$ or less. As result of the research, stable discharge water quality could be secured as result of the MBR effector operation according to rate of inflow and inflow load and treatment efficiency of 98% or higher was shown by the membrane filtering method operation for SS, $BOD_5$. it was found that high treatment efficiency of 99% or higher. It is judged that detention time can be designed until 6.9 hr when applying MBR process on personal sewage treatment facilities with high pollution load and that cutback of pollution load can be possible through this study. It was shown that MBR process application reduces an annual cost of 4,829,600 won based on the basic unit calculation results and solves burden of amount of borne by causers according to excess of discharge water quality standards.

• Proceedings of the Korean Environmental Health Society Conference
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• 2001.04a
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• pp.69-70
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• 2001

• Journal of The Korean Society of Agricultural Engineers
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• v.47 no.5
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• pp.75-86
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• 2005

Recently since urbanization has brought about a dried stream and a worse water quality, Anyang city discharged the third treated sewage into the upper stream of Anyancheon and Hakuicheon. As the result, Hakuicheon had the water level and velocity enough for a living thing in the water to live in but water quality was worse than it had been. Therefore in case of meeting the water level and velocity of the second grade water-quality which living things in the water can live in, the discharge and water quality to secure in-stream flow must be at least 0.350 $m^3/s$ and $BOD_5\;3.2 mg/{\iota}$ respectively. In Anyancheon the water level was increased a little higher than it had been but the velocity was almost unchanged in comparison with it before. On the other hand the water quality was a little better than it had been. Therefore in case of meeting the water level and velocity of the third grade water-quality that people can do water-friendly activity, the discharge and water quality to secure in-stream flow must be at least 0.688 $m^3/s$ and $BOD_5\;4.8 mg/{\iota}$ respectively. The water-quality prediction on the suggested eight scenarios was simulated in all satisfying the third grade water-quality.