• Journal of Korean Society of Environmental Engineers
• /
• v.34 no.1
• /
• pp.1-6
• /
• 2012

Down Stream K River has high COD (4-10 mg/L) and high $NH_3$-N concentration (3.5 mg/L during winter period). Although $NH_3$-N itself is not reported harmful at this level, it must be removed to meet drinking water standard (0.5 mg/L). We constructed a pilot plant modifying the processes of conventional drinking water facilities. Prechlorination and powdered activated carbon (PAC) dechlorination was adopted prior to a flocculation tank to remove ammonia and prevent disinfection byproducts (DBPs) formation. Also, GAC processes was included after sand filter to remove residual DOC. This pilot having a capacity of 36 ton/day was operated for one year. The GAC processes were successful to remove ammonia and many organic pollutants (DOC, MBAS, UV-254 nm absorbance, etc). Influent DOC concentrations were very high as 3~6 mg/L throughout the plant operation. It was impossible to achieve 1.0 mg/L effluent DOC, indicating that bed depth (2 m) should be increased to achieve more strict DOC quality standards. When $Cl_2$ dose was well controlled ($Cl_2/NH_3$-N ratio 10~11 on a weight basis), $NH_3$-N removal was 98% and THMs was very low possibly due to low free residual chlorine and PAC dechlorination.

• Journal of Korean Society of Environmental Engineers
• /
• v.27 no.10
• /
• pp.1035-1042
• /
• 2005

Granular Activated Carbon(GAC) is widely used in drinking water treatment. At S and B Water Treatment Plant, GAC is used in place of granular media in conventional rapid filters(GAC Filter-Adsorber) for removal of Disinfection By-products(DBPs). The primary focus of this study is on the performance of existing filter-adsorber, and their operation. It was found that F/A process removed turbidity as effective as sand system. The ratio of Hydrophobic DOM (HPO) and hydrophilic DOM (HPI) fraction in the raw water at S and B WTP was similar. Filter Adsorber presented earlier DOC breakthrough and steady state condition which was contributed by biodegradation during operation period. The removal efficiency of DBPs were used to evaluate the filter performance. The DBPs concentration of F/A treated water was below treatment goal level (THM < $80\;{\mu}g/L$, HAA < $60{\mu}g/L$). The removal efficiency of THM decreased rapidly during operation period. However, HAA were removed steadily regardless of the influent concentration of HAA. These results indicate that the removal of THM depend upon the adsorption mechanism while the removal of HAA depend upon biodegradation as well as adsorption. The decrease of adsorption capacity and characteristic value of GAC may be attributed to the effect of high organic loading, residual free chlorine, coagulants, manganese oxidants and frequently backwashing. This study has confirmed that Filter adsorber process can be considered as effective alternatives for the removal of DBPs, especially HAA.

• Analytical Science and Technology
• /
• v.28 no.1
• /
• pp.58-64
• /
• 2015

This study aimed to investigate the concentration distributions and formation characteristics of trihalomethanes (THMs) in drinking water supplies to rural communities. Water samples were collected twice from 40 rural households located on the outskirts of Chuncheon city of Gangwon Province in the summers of 2010 and 2011, and urban drinking water samples were collected from 20 faucets during the same period in 2011 for comparison purpose. Water temperature, pH, and residual chlorine (total and free) concentrations were measured in the field, and samples were analyzed for dissolved organic carbon (DOC) and THM concentrations in the laboratory. The average DOC concentrations in rural water samples were not greatly different between groundwater (n = 20) and surface water (n = 20) which were used as sources for drinking water (1.81 vs. 1.91 mg/L). However, the average concentrations of total THMs (TTHMs) in groundwater ($9.77{\mu}g/L$) were much higher than those in surface water ($2.85{\mu}g/L$) and similar to those in urban drinking water samples ($10.8{\mu}g/L$). Unlike urban water supply, rural water (particularly groundwater) contained more brominated THM species such as dibromochloromethane (DBCM), suggesting its relatively high content of bromide ion (Br-). This study showed that rural water supplies have different THM formation characteristics from urban water supplies, probably due to their differences in source water quality properties.

• Korean Journal of Poultry Science
• /
• v.13 no.1
• /
• pp.41-48
• /
• 1986

In order to investigate the storage period of packed chicken meat in relation to the bacterial contamination of each processing part, a special grade poultry processing plant located at Dongdoochun-City, Gyeonggi-Do, was surveyed mainly in point of sanitary conditions. The results are summarized as follows. 1. processing room near reception and packing room next to shipping area showed the highest bacterial counts in air. 2. Equipments and instruments for slaughtering also showed a high degree of bacterial contamination even before the operation. This finding suggested that the possibility of the bacterial contamination of carcasses through equipments and instruments would be high, if the continuous sanitary control measures are not properly taken. 3. The bacterial count of scalding water was 3${\times}$10$\^$7/ for standard plate count and 4${\times}$10$\^$5/ for most probable number of coliform bacteria at 1 hour after the start of operation. These values were maintained until the completion of processing. 4. At the ending of chilling process, the bacterial counts of chilling water were 3.3 ${\times}$10$^4$ and 3.0${\times}$10$^3$for standard plate count, when the volume of water used per bird were 21 and 51, respectively. Bacterial contamination was further decreased about 10$\^$-3/-10$\^$-4/ times as the effective chlorine concentration in chilling water was maintained about 50 ppm. 5. An average standard plate count of the residual water In abdominal cavity of carcasses was 3.9${\times}$10$^4$immediate after chilling, however, it increased to 4.7${\times}$10$\^$7/ when the carcasses were packed and stored for 10 days at 4$^{\circ}C$. off-odour development was observed as the bacterial count was not less than 10$\^$6//$m\ell$ of the residual water of the packed carcasses. Data indicated that if the standard plate count of the residual water in abdominal cavity of carcasses was not less than l0$^4$immediate after chilling, the packed chicken meat would not be stored longer than 5 days at 4$^{\circ}C$.

• Journal of Korean Society of Environmental Engineers
• /
• v.30 no.4
• /
• pp.453-458
• /
• 2008

Laboratory experiments were conducted to investigate disinfection as well as removal of color and residual organics from reclaimed municipal wastewater by electrochemical processes with Nb/Pt anode installed. RNO was rapidly bleached by OH$\cdot$ and the second order rate constants of RNO removal were $\frac{0.223l}{mg{\cdot}min}$, $\frac{1.679l}{mg{\cdot}min}$ and $\frac{2.322l}{mg{\cdot}min}$ with for 5 A, 10 A, and 15 A, respectively, with r$^2$ of > 96%. In batch electrochemical processes, after 15 min at currency of 15 A and initial pH of 5, 7,5 and 9, COD$_{Mn}$ was below 4 mg/L, color unit below 5 degree and general bacteria was not detected, the concentration of which are suitable for drinking water regulation. In the continuous electrochemical process, with HRT of 3.7$\sim$49.2 min, free chlorine were 0.2$\sim$0.7 mg/L, general bacteria was not detected, color unit below 5 degree and THMs was 0.017 mg/L. Therefore, electrochemical process with Nb/Pt anode was employed satisfactory to meet for reusing biologically treated water as well as disinfection.

• Journal of Korean Society of Environmental Engineers
• /
• v.22 no.4
• /
• pp.661-669
• /
• 2000

This research was carried out to evaluate effect of metallic release and change of water corrosive indices by the pH and alkalinity adjustment using the SDLS (Simulated Distribution Loop System) which consist of six types of pipe loop with DCIP, PVC, PE, STS304, CP, GSP, respectively, and its effects on water quality changes which were microbes quality(SPC), residual chlorine. THMs and other parameters. And it was to propose optimal criteria of water quality control for the field application. According to the results, water control system by pH and alkalinity adjustment showed the changing of corrosive water and reducing of metallic release rate and it was not affects of THMs formation, microbes regrowth and variation of other parameters. Water quality stability and corrosion control were due to calcium carbonate precipitation film formation of pipe inner by water quality control. Therefore, corrosive water control system by pH and alkalinity adjustment can be attributed to effective water quality management in water distribution system according to water quality stability of pH and TIC(Total Inorganic Carbonate concentration) that affect the precipitation and dissolution of solids.

• Journal of Korean Society of Water and Wastewater
• /
• v.33 no.5
• /
• pp.353-366
• /
• 2019

This research proposes an optimal flushing operation technique in an effort to prevent secondary water pollutions and accidents in aged pipes, and to improve the cleaning effect of unidirectional flushing. Water flow directions were analyzed using EPANET 2.0, while flushing and air scouring experiments in forward and reverse directions were performed in the field. In 42 experiments, average residual chlorine concentration and turbidity were improved after cleaning compared to before cleaning. It was found that even when the same cleaning method was used, further improvement of cleaning effect was possible by applying air injection and reverse direction cleaning techniques. By means of one-way ANOVA(Analysis of variance), it was also possible to statistically verify the need of actively utilizing air injection and reverse direction cleaning. Based on correlation between turbidity and TSS, the total amount of suspended solids removal was estimated for 874 flushing operations and 194 air scouring operations. The result showed that air scouring used more discharge water than flushing by an average of $4.9m^3$ yet with larger amounts of suspended solids removal by an average of 145.9 g. The result of analysis on turbidity values from 887 flushing operations showed low cleaning effect of unidirectional flushing for the pipes with diameters over 300 mm. In addition, the turbidity values measured during cleaning showed an increasing tendency as pipe age increased. The methodology and results of this research are expected to contribute to the efficient maintenance and improvement of water quality in water distribution networks. Follow-up research involving the measurement of water quality at regular time intervals during cleaning would allow a more accurate comparison of discharge water quality characteristics and cleaning effects between different cleaning methods. To this end, it is considered necessary to develop a standardized manual that can be used in the field and to provide relevant trainings.

• Journal of the Korean Society for Marine Environment & Energy
• /
• v.10 no.3
• /
• pp.127-137
• /
• 2007

To confirm whether or not the Electrochemical Disinfection System (EDS) meet with the D-2 regulation established by IMO (International Maritime Organization), the biological treatment efficacy of the EDS was assessed using three groups of natural marine plankton (bacteria, $10-50\;{\mu}m$ and $>50\;{\mu}m$ sized organisms). Influent water was passed through the EDS under the flow velocity ($23.8\;m^3/hr$) and test design was consisted of control (no treatment) and experimental (10 ppm and 30 ppm) condition for total residual chlorine (TRC). And the biological condition of the influent water followed the standards established by the guidelines for the approval of ballast water management systems. The disinfection efficacy of the $10-50\;{\mu}m$ sized organisms (phytoplankton) was assessed by three kinds of measurements using photomicroscope, epifluorescence microscope and fluorometer (fumer Designs 10-AU). After being passed through the EDS, all motile phytoplankton lost their motility under photomicroscope, the colour of chlorophyll fluorescence fumed from red into green under epifluorescence, and the high chlorophyll fluorescence (Expt. 1: 6.95, Expt. 2: 7.11) detected by fluorometer decreased into value not detected. These results indicated phytoplankton community was totally killed after electrochemical disinfection treatment. Survivorship of the larger organisms than $50\;{\mu}m$ was determined based on the appendage's movement under a stereomicroscope. Natural assemblage collected from ambient seawater was killed shortly after being passed through the EDS, whereas some Artemia remained alive. However, no live Artemia was found after 24 hour further exposure to each TRC concentration (10 and 30 ppm) under darkness. After electrochemical treatment, the target bacteria such as aerobes, coliform and Escherichia coli were completely killed on the basis of CFU (colony forming unit) on Petrifilm plate ($3\;M^{TM}$) after 48 hr incubation. Moreover, no regrowth was found in the three groups of plankton during five days under additional exposure to the treated water. These results indicated that the disinfection efficiency of the EDS on the three groups of plankton satisfy D-2 regulation.