In order to prevent secondary pollution of tap water, corrosion characteristics are investigated, and corrosion index are calculated using LI and LR to manage corrosiveness. As targeted water treatment plants from 2014 (July, once) to 2015 (July and October, 2 times), 70 plants are selected by making a division for each area and water system. (treated water samples, n=240, raw water samples, n=72). In result of pH analysis, treated water was lower than raw water to 7.12, and 7.29, respectively. LI were investigated in the order of Seomjin river, Nakdong river, Han river, Geum river, to -2.08, -1.24, -1.11, -1.10 (at raw water), and -2.18, -1.59, -1.51, -1.35 (at treated water), respectively. In case of water quality goal value (LI = -1) in Japan as control of corrosiveness, management object was investigated about 83.3%.

In this study, we investigated influent and effluent water pollutants in 53 Public Sewage Treatment Works (PSTWs) where industrial wastewater or landfill leachate is combined four times for two years from 2014 to 2015. Also, we analyzed the characteristics of heavy metals and volatile organic carbons at influent and effluent of these PSTWs caused by sewage treatment combined with industrial wastewater or landfill leachate. As a result, six heavy metals such as barium, copper, iron, manganese, nickel and zinc, and four volatile organic carbons (VOCs) including phenols, di(2-)ethylhexyl phthalate (DEHP), formaldehyde and toluene were observed above detection limits in most of PSTWs. Also, it was revealed that six heavy metals such as hexavalent chromium, mercury, cadmium, chromium, nickel and selenium, and four VOCs including 1,1-dichloroethylene, vinyl chloride, naphthalene, and epichlorohydrin were observed more frequently according to precipitation. As a result of reviewing the monitoring data on “Water Quality Monitoring Networks” in lower watersheds of PSTWs, both heavy metals and VOCs were below detection limits, indicating that the effluent water had little influence on the watershed. Nevertheless for the better management of influent and effluent pollutants in PSTWs, it is necessary to establish the advanced management plans for water pollutants in PSTWs, which include a list of priority substances management, monitoring plans, and guidelines for industrial wastewater and landfill leachate combined in PSTWs.

In many countries in order to manage corrosion of water treatment process, it is currently using Langelier index (LI). However, management of the Larson's ratio (LR) to compare corrosion management and LI which can be generated by the water treatment process is required. In this study, in order to ensure data LR, factors associated with the actual corrosion resistance of water treatment plant was measured. Using the measured data, the model equation can be estimated alkalinity, and using the statutory water quality data, LR and alkalinity is estimated. At comparison of the measured value and estimated value of alkalinity, it appeared in R2 = 0.629, using the statutory water quality data and estimated alkalinity model, LR and alkalinity (Whole water treatment plants : 472) is estimated. Concentration of estimated alkalinity is 0.5 mg/L to 107.5 mg/L (average : 23.2 mg/L), and LR is 0.1 to 10 (average : 1.3). At tendency to corrosion of investigated LR, “No metal tendency” (>0.5) is 39 water treatment plants, 8.26 %, and “corrosion metal tendency” is 433 water treatment plants, 91.74%.

Various kinds of processes are used in the Public Sewage Treatment Works(PSTWs) in order to achieve water quality criteria and TMDL in the watershed. The performance of the existing processes at PSTWs depends on influent characteristics, effluent quality target, amount of sludge production, power cost and other factors. In present, the Selection Guideline for the Available Treatment Process of PSTWs is used for a process decision in the country. But there are some problems regarding redundancy of assessment factors and complexity of assessment procedure in the guideline. In this study, we did a test application of AHP for process selection of PSTWs, which propose is to simplify assessment factors such as pollutant removal amount, sludge generation, electricity consumption, stability of operation, convenience of maintenance, easiness of existing process application, installation cost, and operating cost concerning of environmental factors, technical factors and economical factors. According to the study, the PSTWs selection procedure guideline can be improved using application of AHP method.

As the Enforcement Ordinance of Environmental Policy Act was revised in 2013, total organic carbon(TOC) was added as an indicative parameter for organic matter in Water and Aquatic Ecosystem Environmental Criteria. Under these imminent circumstances, a regulatory standard is needed to achieve the proposed TOC limitation control water quality from the public sewage treatment plants(PSTWs). This study purposes to present the determination method for TOC effluent limitation at the PSTWs. Therefore we investigate the TOC effluent limitation of foreign countries such as EU, Germany and USA, and analyse the effluent water qualities of PSTWs. In using these TOC data, we review apprehensively the statistics-based, the technology-based, and the region(water quality)-based determination method of TOC effluent limitation for PSTWs.

In accordance with the Watershed Sewer System Maintenance Plan enforced on February 2, 2013, the different compliance concentration of effluent limit be applied to effluent discharged from public sewage treatment works(PSTWs) in each watershed on the basis of water quality thereof. With the introduction of watershed sewer system, it is necessary to set the compliance concentration of effluent limit for PSTWs situated in the watershed, by region and PSTW size, to achieve water quality criteria for regional watersheds or target water quality under TMDL program. Watershed Environmental Agencies establish the Watershed Sewer System Maintenance Plan and set the compliance concentrations of effluent limit for PSTWs under the plan. The agencies plan to apply tougher effluent BOD concentration limits in Class Ⅰ to Ⅳ areas. Effluent BOD concentration limits will be toughened from 5~10 mg/L to 3 mg/L in class Ⅱ~Ⅲ areas, from 10mg/L to 5mg/L in class Ⅳ areas. Uniform application of effluent BOD concentration limits to PSTWs in the watershed sewer system need to be complemented considering type of sewage treatment technology employed and watershed characteristics. Therefore, this study presents method to determine the compliance concentration of effluent limit from PSTWs in the watershed.

Under Korea’s Enforcement Decree of the Framework Act on Environmental Policy amended in 2013, total organic carbon (TOC) is newly added as water quality parameter to assess organic pollution in the aquatic ecosystem. To meet the TOC requirement and improve quality of effluent discharged into public watershed, it is also necessary to develop standards for TOC in effluent from public sewage treatment works (PSTWs).In this study, we reviewed the characteristics and removal efficiency of TOC in influent and effluent of PSTWs. The study found that phosphorus treatment process removed not only soluble phosphorus but also a portion of TOC remaining after the secondary treatment process. TOC concentration in effluent from PSTWs operated in tandem with industrial wastewater treatment work was higher due to influx of insoluble substances from the industrial wastewater treatment work.In order to lay a foundation for the management of TOC from PSTWs, it is necessary to carry out research on TOC from different perspectives. For example, studies on the generation mechanism of TOC and the impact of TOC on drinking water resources, assessment of effluent qualities through monitoring, and development of measures to control TOC for the preservation of aquatic ecosystem are needed.

Mechanical properties of concrete such as compressive strength and elastic modulus are affected by the moisture inside the concrete members. Concrete specimens with various diffusion conditions are tested and the relations between the pore relative humidity and mechanical properties are suggested based on the experimental results. Suggested models are applied to the experimental results in the previous researches and the comparison results show that the models are reasonable.