• Journal of Korean Society on Water Environment
• /
• v.24 no.6
• /
• pp.641-650
• /
• 2008

This paper reviews the infrastructure of the water supply and sewerage system in North Korea. North Korean has similar legal protection to preserve water environment that can be seen in Republic of Korea, but North Korean regulations seemed lack of detailed measures. The critical pollution problems of rivers and lakes in the northern part of peninsula is mainly due to the lack of sewage collection system and poor treatment works. It has been estimated that less than 20% of sewers are connected to the wastewater treatment plants. Although the availability of water resources seemed sufficient, North Koreans suffer the lack of the drinking water supply which needs an urgent attention. Based on the analysis, it has been suggested that the reconstruction of North Korean water and sewage infrastructure needs at least 17.5 trillion Korean Won.

• Journal of Korean Society of Water and Wastewater
• /
• v.29 no.4
• /
• pp.447-457
• /
• 2015

Water cycle within the human civilization has become important with urbanization. To date, water cycle in the eco-system has been the focus in identifying the degree of water cycle in cities, but in practicality, water cycle within the human civilization system is taking on an increasing importance. While in recent years plans to reuse water have been implemented to restore water cycle in cities, the effect that such reuse has on the entire water cycle system has not been analyzed. The analysis on the effect that water reuse has on urban areas needs to be go beyond measuring the cost-savings and look at the changes brought about in the entire city's water cycle system. This study uses a SWAT model and water balance analysis to review the effects that water reuse has on changes occurring in the urban water cycle system by linking the water cycle within the eco-system with that within the human civilization system. The SWAT model to calculate the components of water cycle in the human civilization system showed that similar to measured data, the daily changes and accumulative data can be simulated. When the amount of water reuse increases in urban areas, the surface outflow, amount of sewer discharge and the discharged amount from sewage treatment plants decrease, leading to a change in water cycle within our human civilization system. The determinant coefficients for reduced surface outflow amount and reduced sewer discharge were 0.9164 and 0.9892, respectively, while the determinant coefficient for reduced discharge of sewage treatment plants was 0.9988. This indicates that with an increase in water reuse, surface flow, sewage and discharge from sewage treatment plants all saw a linear reduction.

• Journal of Wetlands Research
• /
• v.22 no.4
• /
• pp.321-327
• /
• 2020

Recently The amount of wastewater and linked wastewater is being increased every year due to industrial development, population growth, and improvement in living standards. Linked wastewater shows the feature-low flow rate and high concentration. Therefore, it has been shown that it has a great impact on the operation of the sewage treatment plant and costs a lot for treating linked wastewater. In this study, a scenario with low increase of water quality when the total amount of the inflow of linked wastewater was entered into individual reactors is obtained. According to the result of modeling, The effluent water quality get the least increment once the water was introduced into the influent and anoxic tank. We generated the various scenarios Based on these results. scenarios are varying according to inflow from linked waste water's distribution ration. As a result of modeling through various scenarios, it was found that the increment of TN and TP were at the least when the inflow of linked water was distributed with ratio between sewage (80%) and oxygen-free tank (20%).

• Journal of Korean Society of Water and Wastewater
• /
• v.27 no.5
• /
• pp.603-610
• /
• 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 of Coastal and Ocean Engineers
• /
• v.19 no.4
• /
• pp.385-398
• /
• 2007

It was analysed that spatial and temporal change patterns of general water quality constituents were measured monthly from 2002 to 2005 in Jumunjin Harbour. The measured constituents are temperature, salinity, pH, SS and DO. Concentration difference of upper lower layer for general water quality constituents was small. Temperature and DO concentration show the clear difference at temporal concentration change pattern, but SS, pH and salinity have irregular change pattern. Also, water quality improvement effect of seawater exchange facilities and sewage treatment plants is analysed quantitatively using averaged spatial and temporal data set. From this result, it is found that effect of sewage treatment plants is small and seawater exchange facilities at zone 1 and 2 is clear concentration reduction effect to be about 26% and 16%, respectively. After sewage treatment plants operation, DO concentration reduced about 10% at inner zone of Jumunjin Harbour, the other side, after seawater exchange facilities concentration DO concentration increased about 10%. DO concentration at 2005 estimated little than that of 2002, it is concluded that a yearly change of DO concentration has about 10%.

• Journal of Korean Society of Water and Wastewater
• /
• v.18 no.1
• /
• pp.59-65
• /
• 2004

The change of the microbial community structure in excess sludge of different sewage treatment plants by ozone treatment was investigated by quinone profiles. The resulting ozone dosage ranged from 0.1 to $0.4gO_3/gTS$. In terms of overall sludge reduction, more than 50% reduction of the total sludge mass could be achieved by ozone treatment at $0.4gO_3/gTS$. Quinone concentration and type in sludge of different treatment plants were remarkably decreases with increasing ozone dose. Ubiquinones(UQs)-8, -10 and MK-8 were still remained in the ozonized sludge at $0.4gO_3/gTS$. The results of this study showed that the remaining microorganisms belong to UQs-8, -10 and MK-8 were difficult to destruct cell membrane or wall by ozonation. Fecal Streptococci and Salmonella were not detected at ozone dose of $0.2gO_3/gTS$, but Fecal Coliform was not detected at ozone dose of $0.4gO_3/gTS$.

• 제어로봇시스템학회:학술대회논문집
• /
• 1991.10a
• /
• pp.922-927
• /
• 1991

This study is aimed to investigate a design problem of the fuzzy logic controller for the activated sludge process(ASP) in sewage treatment. The modeling technique proposed by Sugeno is used to express the ASP effectively and identification of a fuzzy model of the ASP is carried out utilizing actual operational data obtained from a metropolitan sewage plants. The model-based fuzzy controller is designed by rules generated from the identified ASP fuzzy model. Feasibility of the designed controller is tested through computer simulations.

• Journal of Environmental Health Sciences
• /
• v.36 no.2
• /
• pp.141-147
• /
• 2010

Indicator bacteria of fecal pollution were enumerated and compared by various detection methods for influent and final effluent of a sewage treatment plant. Total coliforms were enumerated by four methods including most probable numbers, chromogenic enzyme substrate test, membrane filtration, and plate counts and were about $10^4$ for influent and $10^2{\sim}10^3\;CFU/ml$ for final effluent. Fecal coliforms ranged between $10^3$ and $10^4$ for influent and $10^2\;CFU/ml$ for effluent by chromogenic enzyme substrate test and membrane filtration. Fecal streptococci counts were 1-log less than fecal coliforms counts, $10^2{\sim}10^3$ for influent and $10^1\;CFU/ml$ for effluent. Total coliforms numbers by plate count both in influent and in effluent showed 1-log higher than by the other three methods. Statistical analysis revealed that numbers of total coliforms by plate count in final effluent had the highest average of correlation (r=0.778, p<0.01) compared with those by the other three methods. In addition, total coliforms numbers by plate count showed most significant correlation (r=0.835, p<0.01) with those by chromogenic test which is well-known as its highest recovery efficiency. These results suggest that the plate count would be the optimum detection method for total coliforms in wastewater treatment plants which are the only microbiological standard of final effluent from wastewater treatment plants in the Republic of Korea, considering economic aspects and difficulties in laboratories.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.16 no.2
• /
• pp.81-87
• /
• 2008

We have investigated the efficacy and efficiency of the used briquets for the sewage treatment in this study. The effluent of wastewater treated by Used Briquets Process (UBP) showed very low values of $BOD_5$, CODcr, and SS (1.1 mg/L, 9.5 mg/L, and 3.8mg/L, respectively), which corresponded to 99%, 92.7%, and 96.3% of removal efficiency to the raw wastewater. The number of total bacteria and E. coli in the effluent water treated by UBP was found to be 9 and 1.2 cfu/ml, respectively, showing the remarkable decrease in number, when compared to that of other sewage treatment plants. In the long period of experiment over 1 year, UBP has also shown the high removal efficiency with less sludge production, and low seasonal fluctuation of the values. This UBP is very environmentally-friendly process in the aspects of recycling used briquets and reducing the sludge production. We think that this process will be useful for both the small-scale sewage treatment and reuse of the effluent water.

• Journal of Korean Society on Water Environment
• /
• v.20 no.3
• /
• pp.275-280
• /
• 2004

This study was performed to investigate the disinfection efficiency and the formation characteristics of disinfection by-products(DBPs) by chlorination in the sewage effluent. The effluent was sampled from the sewage treatment plants operated in the activated sludge process and the advanced sewage process. The type of DBPs investigated were Trihalomethanes(THMs), Dichloroacetonitrile(DCAN), Chloral hydrate(CH), Dichloroacetic acid(DCAA), Trichloroacetic acid(TCAA). Major findings are as follows. First, the optimum injection concentration for chlorination in sewage effluent were found to be in the range $0.5{\sim}1.0mg\;cl_2/L$. Also, It was found that the chlorine dosage in the effluent of activated sludge process was higher than in the effluent of advanced sewage process. Second, the maximum formation concentration of THMs were $12.7{\mu}g/L$. The THMs formation reaction was finished in a short time of several seconds and chloroform was mainly formed. Also, it was found that the concentration of ammonium nitrogen is higher, the concentration of THMs is lower. Third, it was found that DCAA and TCAA were mainly formed as DBPs by disinfection.