A dynamic water quality model is presented in order to simulate water quality under slowly varying flow conditions over time. To improve numerical accuracy, the proposed model uses a lumped system approach instead of extended period simulation, unlike the other available models. This approach can achieve computational efficiency by assuming liquid and pipe walls to be rigid, unlike the method of characteristics, which has been successfully implemented in rapidly varying flows. The discrete volume method is applied to resolve the advection and reaction terms of the transport equation for water quality constituents in pipes. Numerical applications are implemented to the pipe network examples under steady and unsteady conditions as well as hydraulic and water quality simulations. The numerical results are compared with EPANET2, which is a widely used simulation model for a water distribution system. The model results are in good agreement with EPANET2 for steady-state simulation. However, the hydraulic simulation results under unsteady flows differ from those of EPANET2, which causes a deviation in water quality prediction. The proposed model is expected to be a component of an integrated operation model for a water distribution system if it is combined with a computational model for rapidly varying flows to estimate leakage, pipe roughness, and intensive water quality.

In order to determine reduction of greenhouse gas emissions (GHGs) when the submerged membrane bioreactor with granular sulfur (MBR-GS) is used in wastewater treatment plant (WTP), the amount of GHGs was compared and analyzed in the advanced treatment process of P wastewater treatment plant (WTP). The amount of GHGs was estimated by classifying as construction and operation phase in WTP. The amount of GHGs in construction phase was evaluated from multiplying raw materials by using carbon emission factors. Also the amount of GHGs in operating phase was calculated by using total electricity consumption and carbon emission factor. The construction of anoxic tank and secondary settling tank is unnecessary, because the MBR-GS conducts simultaneously the nitrification and denitrification in aeration tank and filtration by hollow fiber membrane. The amount of $CO_2$, $CH_4$, and $N_2O$ emitted by constructing the MBR-GS was 6.44E+06 kg, 8.16E+03 kg and 1.38E+01 kg, respectively. The result shows that the GHGs was reduced about 47 % as compared with the construction in the MLE process. In operating the MBR-GS, the electricity is not required in the biological reactor and secondary setting tank. Thus, the amount of $CO_2$, $CH_4$, and $N_2O$ emitted by operating in the MBR-GS was 7.39E+05 kg/yr, 5.80E+02 kg/yr and 2.44E+00 kg/yr, respectively. The result shows that the GHGs were reduced about 37 % as compared with the operation in the MLE process. Also, $LCCO_2$(Life Cycle $CO_2$) was compared and analyzed between MLE process and MBR-GS. The amount of $LCCO_2 $emitted from the MLE process and MBR-GS was 3.56E+04 ton $CO_2$ and 2.12E+04 ton $CO_2$, respectively. The result shows that the GHGs in MBR-GS were reduced to about 40 % as compared in the MLE process during life cycle. As a result, sulfur-utilizing autotrophic denitrification process (SADP) is expected to be utilized as the cost-effective advanced treatment process, owing to not only high nitrogen removal efficiency but also the GHGs reduction in construction and operation stage.

This study focuses on the feasibility of bio-gas production using anaerobic digestion by measuring methane generation and biodegradability through the BMP test of industrial organic wastes. Organic wastes consist of entrails of pigs and organic residues of rumen generated from slaughter houses, wastewater sludge from slaughter waste water, fish offal and residues of vegetables from public wholesale markets, and wastewater sludge from the process of wastewater treatment in paper mill. The cumulative methane production by BMP test ranges from 149.3 ml/g-VS to 406.6 ml/g-VS and this is similar to methane generation of the normal wastewater sludge and food waste. As a result of measurement of biodegradability, wastewater sludge (S1 ~ S4) is low, ranging from 27.1% to 58.9 % and organic residues of rumen (G1) is low at 49.6 %. In conclusion, it turned out that raising the hydrolysis by various pre-treatments is necessary in order to produce bio-gas by using industrial organic wastes.

Recent series of flooding events in urban area has brought a growing concern on storage facilities as a major stormwater management method. The Korean Ministry of Environment has announced diverse plans to tackle the problem, including plans for multi-purpose storages which deal both the stormwater and wastewater. Even though storages can be categorized for different perspectives, classification of possible storages in urban area has not been throughly studied so far. This study investigated diverse references of urban storages and suggested systematic classifications on structural, functional and some other basis. Structural classification mainly concerns structural shape of facilities and includes (1)Cisterns & Rain barrels, (2)Forebays, (3)Dry basins, (4)Wet basins and (5)Constructed wetland. Those functions can be (1)flood prevention (2)water quality control and (3)reuse of stored water. Other criteria that categorize storages depend on (1)height, (2)location, (3)configuration, (4)depth, (5)site of the installation and (6)shape.

In this study, the influencing factors for efficient anaerobic digestion of high strength ammonia-nitrogen wastewater removal were investigated by testing biochemical methane potential test. In the influencing factors, the trace metals which could increase activity of anaerobic microorganisms, microbial concentration and types were evaluated. In the results, trace metals supplementation showed gas production amount higher than those without addition of trace metals. Among the tested trace metals, B, Ni, and Se were preferable to gas production. In the result of gas production according to the microbial concentration, the amount of gas production was proportional to the microbial concentration. In addition, the shortest lag time and the fastest gas production rate were achieved when the highest microbial concentration was tested. granule-type microorganism produced more gas than suspended-type microorganism. In conclusion, the efficient anaerobic digestion for high strength ammonia-nitrogen wastewater removal could be achieved by applying necessary trace metals injection and high concentration granule type microorganism.

In Korea, almost every water treatment plant suffers from seasonal problem of algae and turbidity which result from eutrophication and heavy rainfall. To relieve this problem, experimental investigation was performed to study the applicability of a floating-media and sand filter to preliminary water treatment in terms of algae and turbidity removal. Experimental results using pure-cultured algae influent showed that the shape of algae species as well as filtration velocity affects the removal efficiency. From the experiments using natural river water, it was concluded that algae removal is more sensitive to floating-media depth but turbidity more sensitive to sand depth. As the filtration velocity increased, the removal of turbidity decreased but that of algae was not affected. The floating-media and sand filter removed more than 30 % of TP, TN, turbidity, Chl-a and CODcr, and less than 20 % of DOC and $UV_{254}$.

The water supply pipes are buried across wide range of areas, so it is hard to spot them using excavation and takes a large amount of expense. Thus, there is a high risk for direct research and application, accompanying many difficulties in implementation of them. Therefore, it is more economical and convenient to use indirect evaluation variables than direct evaluation of the buried pipes in assessing the degree of pipe deterioration. To assess the degree of pipe deterioration using the indirect evaluation variables, it should be done first to identify how and to what extent they affect the degree of deterioration. This study measured the evaluation variables for pipe deterioration using the pipe endoscope and analyzed the measurement results and the degree of impact on the pipes. In addition, this study attempted to evaluate the adequateness of the pipe deterioration evaluation using the indirect variables based on the analysis results. The evaluation variables measured through the pipe endoscope were the thickness of sediments, size of scale, degree of desquamation and condition of connections. For the indirect evaluation variables, the data such as the property data from GIS pipe network map as well as the material, diameter, age and pipe lining material of the pipe, road type, leakage frequency, average water velocity and water pressure using the leakage repair records was collected. Using the collected data, this study comparatively analyzed the indirect evaluation variables for the degree of pipe deterioration and the results from the pipe endoscope to choose appropriate variables for pipe deterioration evaluation and calculated the weights of the indirect variables on the degree of deterioration. The results showed that the order of the impact of indirect variables on deterioration was pipe age > pipe lining material > road type > leakage frequency > average water velocity with their weights of 0.45, 0.20, 0.15, 0.10, and 0.10, respectively. Conclusively, the results suggest that the measures of sediment thickness, scale size, degree of desquamation and condition of connections are appropriate for the evaluation of pipe deterioration and sufficient for the analysis of the impact of the indirect variables on deterioration.

UV technology is widely used in water and wastewater treatment. Many researches have been conducted on microbial disinfection and micro pollutant reduction with UV treatment. However, the study on NOM with UV has limited because low/medium pressure UV lamp is not sufficient to affect refractory organics such as NOM. Pulsed UV treatment using UV flash lamp can be operated in the pulsed mode with much greater peak intensity. The pulse duration is typically in microseconds, whereas the interval between pulses is in the order of milliseconds. The high intensity of pulsed UV would mineralize NOM itself as well as change the characteristics of NOM. Chlorine demand and DBPs formation is affected on the changed amounts and properties of NOM. The objective of this study is to investigate the effect on NOM, chlorine residual, and chlorinated DBPs formation with pulsed UV treatment.

Leakage in water supply system can cause water resources loss in addition to the water quality degradation. In this research, leakage reduction after establishment of a block system in the area with leakage rate of 69.0 % was investigated using EPANET simulation. The average water pressure for the research area was $5.17kgf/cm^2$ which was relatively high, and several sites were deviated from recommended water pressure ranges(i.e., 1.5 ~ $7.1kgf/cm^2$). However, the average water pressure in the area was reduced to 3.81 and $3.49kgf/cm^2$ after the introduction of block system with a water pressure relief valve(PRV) setting of 3.0 and $2.5kgf/cm^2$, respectively. Under the installation of a PRV with regulating pressure of $2.5kgf/cm^2$, the predicted leakage was reduced from $4,420.3m^3/d$ to $3,028.1m^3/d$, which was equivalent to the leakage reduction from 31.0 % to 23.5 %.

Selecting Daechung Dam as a sample study site, this study simulates virtual water quality incident which can be occurred using EFDC maintained by USEPA. In order to predict the behavior and diffusion of leaked conservative pollutant within dam under the worst condition, the hydrological data and information from 2008 were used. EFDC was successfully calibrated for observed water level obtained from the above sources. From the results of simulations, even though the concentrations (500 ppm, 1,000 ppm and 10,000 ppm) of leaked pollutant were different with each other at the same sources, the travel time of each peak concentration appeared similar. Also, changing the leak source point from dam gate(0 km) to 7 km, it was found that as leak source point was nearer to the dam gate, the travel time of each peak concentration showed up sooner. It was simulated to take 1 day to 15 days for initial appearance of the leaked pollutant according to the leaked points, and 3 days to 25 days for the reach of the peak concentration, respectively.

강이나 호수로 유입되는 인(P)이 종종 부영양화의 가장 큰 제한요소로 작용한다. 그런데 하수처리장의 방류수가 자연수계에 인의 중요한 공급처로 작용하는 경우가 많기 때문에 하수처리장의 최종 처리수에서 인의 제거가 요구된다. 하수에서 인을 제거할 수 있는 많은 기술 중에서, 활성 칼슘-황토의 복합체를 이용한 흡착기술을 연구하였다. 칼슘을 황토에 첨가하여 인의 흡착 용량과 흡착강도를 증가시켰다. 칼슘을 첨가한 황토를 최적 온도로 밝혀진 $400^{\circ}C$의 고온에서 활성화시켰다. $400^{\circ}C$ 미만에서 활성화시킨 칼슘-황토는 하수처리 공정의 활성칼슘-황토 복합체를 이용한 처리조에 적용하기엔 강도가 부족하였다. 반면 $400^{\circ}C$ 초과 온도에서 활성화시킨 칼슘-황토 복합체는 복합체 표면이 유리화되어 흡착용량이 감소하였다. 활성칼슘-황토 복합체는 표면에 충분한 기공이 발달하지 못하여 인의 흡착용량에 한계는 있으나 칼슘을 첨가하였기 때문에 흡착강도는 높았다. 활성칼슘-황토는 입자형 복합체로 만들어졌다. 제조된 복합체를 흡착칼럼에 채워 하수처리공정에 적용하였다. 활성칼슘-황토의 복합체를 충진한 칼럼을 파일롯트 플랜트에 적용한 결과 0.5 mg/l의 인의 농도를 0.1 mg/l로 낮출 수 있었고, 이온성 인을 4개월의 운전기간 동안 완전하게 흡착시켜 제거할 수 있었다.