• Journal of Environmental Impact Assessment
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• v.21 no.4
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• pp.543-552
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• 2012

Namgang mid-watershed is located in downstream of Nakdong river basin. There are many pollution sources arround this area and it's control is important to manage a water quality of Nakdong river. A target year of Namgang mid-watershed water environment management plan is 2013. To predict a water quality at downstream of Namgang, we have investigated and forecasted the pollutant source and it's loading. There are some plan to construction the sewage treatment plants to improve the water quality of Nam river. Those are considered on predicting water quality. As results, it is shown that the population is 343,326 and sewerage supply rate is 79.2% and the livestock is 1,662,000 in Namgang mid-watershed. It is estimated that the population is 333,980, the sewerage supply rate is 86.9% in 2013. The milk cow and cattle were estimated upward and the pigs were downward by 2013. The generated loading of BOD and TP is 75,957 kg/day and 4,311 kg/day, discharged loading is 18,481 kg/day and 988 kg/day respectively in 2006. It were predicted upward the discharged loading of BOD and TP by 4.08% and 6.3% respectively. The results of water quality prediction of Namgang4 site were 2.5 mg/L of BOD and 0.120 mg/L of TP in 2013. It is over the target water quality at that site in 2015 about 25.0% and 9.1% respectively. Consequently, there need another counterplan to reduce the pollutants in that mid-watershed.

• Journal of Korean Society of Water and Wastewater
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• v.27 no.1
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• pp.113-120
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• 2013

This study aimed to obtain quantitative data for WWTP operators in phosphorus removal process. This was done by reviewing and comparing phosphorus removal efficiency(%), coagulants dosage(Al/P and $Al_2O_3$(mg/L)), sludge production($kg/m^3$), and operation cost($won/m^3$) of start-up and normal operation data. Phosphorus removal efficiency of all tertiary treatment process was up to 70 ~ 89 % in start-up and normal operation. Average molar ratio(Al/P) was similar as 5 in both operations, but average coagulants dosage (mg/L) of start-up (8.5 mg/L) was higher than normal operation (6.2 mg/L). Average operation cost was higher for start-up ($33.6won/m^3$) than normal operation ($28.4won/m^3$), while electricity cost required for the normal operation ($9.0won/m^3$) was higher by $3.5won/m^3$.

• Journal of Wetlands Research
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• v.18 no.3
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• pp.267-274
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• 2016

Sewerage supply in rural community is the important for water quality protection of water system such as river, lake and wetland. And characteristic of small scale wastewater system that have wide range of inflow and concentration in sewage should be considered for stable operation of small scale wastewater treatment plant. In this research, characteristics of flow ratio (flow / designed flow), effect on treatment efficiency of small scale wastewater treatment plant and assessment of optimal flow ratio were conducted through analysis on operation result of 18 small scale wastewater treatment plant in Bong-hwa gun. As a result, flow ratio shows the higher value during summer. However pollutants concentration in sewage was shown the higher concentration during autumn and winter. Treatment of small scale wastewater treatment plant is increased when flow ratio increased, and nutrient treatment efficiency is more sensitive to change of flow ratio than organic compound and suspended solids. According to this research result, it need to be maintained flow ratio 0.8 over value for stable treatment efficiency of small scale wastewater treatment plant.

• Advances in environmental research
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• v.9 no.4
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• pp.233-249
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• 2020

To date, there is no central wastewater (WW) treatment plant in Erbil city, Kurdistan region, Iraq. Therefore, raw WW disposes to the environment and sometimes it used directly for irrigation in some areas of Erbil city. Disposal of the untreated WW to the natural environment and using for irrigation it causes problems for the people and the environment. The aims of the current work were to study the characteristics, design of primary and different secondary treatment units and reusing of produced WW. Raw WW samples from Ashty city-Erbil city were collected and analyzed for twenty three quality parameters such as Total Suspended Solids (TSS), total dissolved solids, total volatile and non-volatile solids, total acidity, total alkalinity, total hardness, five-day Biochemical Oxygen Demand (BOD5), Chemical Oxygen Demand (COD), biodegradability ratio (BOD5/COD), turbidity, etc. Results revealed that some parameters such as BOD5 and TSS were exceeded the standards for disposal of WW. Design and calculations for primary and secondary treatment (biological treatment) processes were presented. Primary treatment units such as screening, grit chamber, and flow equalization tank were designed and detailed calculation were illustrated. While, Conventional Activated Sludge (CAS), Sequencing Batch Reactor (SBR) and Moving Bed Biofilm Reactors (MBBR) were applied for the biological treatment of WW. Results revealed that MBBR was the best and economic technique for the biological treatment of WW. Treated WW is suitable for reusing and there is no restriction on use for irrigation of green areas inside Ashty city campus.

• Journal of Korean Society on Water Environment
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• v.30 no.5
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• pp.524-531
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• 2014

Korea has been trying to manage water quality of rivers and lakes in many ways. Ministry of Environment is making continuous efforts of operation control improvement such as strengthening effluent standards in sewage treatment plants and expanding Tele-Monitoring System (TMS). However, evaluation method for operations of sewage treatment plants and establishment system of effluent standards are inadequate. The objective of this study is to evaluate for operations of sewage treatment plants using statistics technique such as frequency analysis, percentile, normal distribution analysis. We used the effluent data (BOD, COD, SS) collected at 299 plants in 2012. The values were very low by comparison with standards. The Data followed a normal distribution. We think that distribution characteristics are closely related with effluent standards, especially T-P and BOD. Statistics technique attempted in this study can be used to evaluate for operations of sewage treatment plants and assess the appropriateness of effluent standards based on TBEL(Technology-based effluent limitation). And, this technique can be used to figure out the overall level of plants, the status of each plant and the favorable treatment process for each item (BOD, COD etc.). Data acquired through this method can be used to improve facilities and operation techniques and decide on a sewerage policy.

• Journal of Korean Society on Water Environment
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• v.33 no.6
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• pp.754-768
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• 2017

Polybrominated diphenyl ethers (PBDEs) are a group of industrial aromatic organobromine chemicals that have been used since the 1970s as flame retardants in a wide range of consumer products and articles, including plastics, computers, textiles and upholstery. Commercial PBDEs were added to Annex A of the Stockholm Convention as persistent organic pollutants in May 2009. PBDEs are still frequently found in sludge and effluent from wastewater treatment plants, even though commercial PBDEs were prohibited or voluntarily phased out several years ago. Conventional wastewater treatment processes are not designed to effectively remove PBDEs. This indicates that there is an urgent need for new developments and improvements to enhance upon the treatment techniques which are currently available. Several studies have suggested the potential removal and degradation technologies for PBDEs in wastewater. In this study, the concentrations and compositional profiles of PBDE congeners in sludge and effluent are investigated by analyzing the relevant literature data in relation to their usage patterns in commercial products in North America and South Korea. The strengths and weaknesses of the current PBDEs removal techniques (i.e., biodegradation, zero-valent iron, photolysis, sorption, etc.) are discussed critically. In addition, future research direction regarding the treatment and removal of PBDEs from wastewater is also suggested, based on the literature review.

• Journal of Environmental Health Sciences
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• v.32 no.5 s.92
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• pp.469-477
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• 2006

When denitrification was connected with a single stream process by using biofilter and sulfur-limestone, it was found that such connection enabled highly efficient nitrification without special unit operation of microorganisms or injection of external carbon sources which is being shown in general biological treatment processes. It was observed that in the trickling filter bed, decomposition of organic substances and highly efficient nitrification by both the forced pressure feed trickling and the air fan were simultaneously done. In the denitrification tank where sulfur-limestone was mixed at a certain ratio, limestone was used by autotrophic microorganisms as a source of supply for alkalinity, and nitrate $NO_{3}^{-}$-N was denitrified into nitrogen gas. And in the sulfur-limestone autotrophic denitrification, $NO_{3}^{-}-N\;or\;NO_{2}^{-}-N$ was denitrified as a sulfur compound in reduction state was oxidized into a final output of $SO_{4}^{-2}$. The mean concentration of the discharge water was 8.6 mg/l for T-N and 0.8 mg/l for T-P, respectively, and their mean treatment efficiency was 79.2% and 80.8%, respectively. Implementing highly efficient denitrification without injection of an external organic carbon source or internal return, it is concluded that the proposed process is suitable for a sewerage in a small village with the merits of low power consumption and easy maintenance.

• Journal of Korean Society on Water Environment
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• v.33 no.3
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• pp.359-369
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• 2017

Water distribution systems supply drinking water to consumers' taps. Internal corrosion of metallic pipe used in drinking water distribution systems has reduced water quality and led to increased levels of toxic heavy metals such as lead, copper and nickel. These problems have been experienced to varying degrees by water utilities in many countries. North America has successfully managed and controlled pipe corrosion and corrosive water in water distribution system based on various policies, regulations and rules. Practical and engineering guidelines for evaluation of pipe corrosion and determination of treatment options are also provided to assist drinking water supplies. In addition, the corrosion mechanism in water distribution systems, such as the complex effects of physical and chemical parameters on the corrosion pipes has been improved to accurately predict corrosion rates of metallic pipes in actual water distribution systems. This paper reviews various regulations, policy statement, and treatment produces on controlling corrosion in drinking water distribution systems in US and Canada and then offers suggestion for management of corrosive water and pipe corrosion in drinking water distribution system in Korea.

• Journal of Korean Society of Water and Wastewater
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• v.22 no.6
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• pp.647-655
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• 2008

Sewer Rehabilitation Project (SRP) is planed, designed and constructed to perform its intended performance as sewerage delivery systems. Recently, a subject of performance evaluation methodology development for SRP has become a great deal of concern among researchers in Korea. From the view point of Sewage Treatment Plant (STP), however, the estimation of improvement efficiency for SRP is in lack of reliability due to the fact that affections for the treatment efficiency and operating condition are not reflected on SRP design and construction. In this study, statistical methodology was used in the analysis of data, which are taken during 1,186 days ($1^{st}$ Jan. 2005 - $31^{th}$ Mar. 2008) from the influent, effluent and operating conditions of full-scale STP($25,000m^3/d$). Then the effect of SRP on the influent characteristics and operating conditions changing was compared and evaluated. Results from the statistical evaluation show that SRP causes characteristic changes in influent and exerts a significant effect especially on the performance of STP.

• Journal of Korean Society of Water and Wastewater
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• v.33 no.2
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• pp.103-110
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• 2019

Management of stormwater runoff is considered a nationwide challenge. To deal with this challenge, many researches have been conducted to study initial stage of stormwater fee imposition. The objective of this study was to recommend a framework for stormwater fee imposition not only for funding the stormwater management programs but also for encouraging people to decrease impervious area. This study focused on, regulations, financial resources and international cases related to stormwater runoff management. Polluter pays principle, which is generally recognized environmental policy principle is regarded the basis of stormwater fee imposition. Three components suggested for the stormwater rate structure are 1) stormwater utility revenue requirement, 2) billable equivalent stormwater unit, 3) system unit cost. The key point of stormwater rate structure is the "Equivalent Residential Unit(ERU)". The concept of an ERU is one residential area with a runoff coefficient. The runoff coefficient is that portion of rainfall that becomes runoff rather than infiltrating into the ground. In addition to this, this study took into account the observed data simulation for the separation of stormwater treatment expenditure from the comprehensive wastewater treatment cost.