• Journal of Korean Society of Disaster and Security
• /
• v.12 no.1
• /
• pp.23-34
• /
• 2019

It is an urgent issue to manage and reduce non-point pollution sources for improving the water quality of stream and lakes in rural areas. In this study, in order to reduce non-point pollution sources in rural area, Gabion mattresses was proposed to provide protection of riverbanks with anaerobic and aerobic area. The utilization of this was assessed by lab scale model test and pilot plant test. After filling the inside of the gabion mattresses with aggregate, the filtration zone under anaerobic and aerobic conditions was formed to treat the contaminants. In addition, vegetation was deposited on the surfae of the gabion to prevent the inflow of soil and to promote purification by the plant. COD and nitrogen content (T-N, $NH_4{^+}$, -N, $NO_3{^-}N$) were monitored in model and field tests. The lab scale model test showed removal efficiency of 17% of TCOD, 35% of SCOD, 14% of TN, 62% of $NH_4{^+}$, -N, and 33% of $NO_3{^-}$ N. Also, pilot plant test showed removal efficiency of 24% of TCOD, 29% of SCOD, 47% of TN, 50% of $NH_4{^+}-N$, 33% of $NO_3{^-}$, N and 29% of TP.

• Korean Journal of Ecology and Environment
• /
• v.42 no.2
• /
• pp.161-171
• /
• 2009

A 'continuous removal of organic matters (CROM) system' using a native freshwater bivalve in Korea Anodonta woordiana, was developed to determine its potential of controlling various sestons in eutrophic lake system, and to evaluate its effect on water quality improvement under consideration of sediment addition as habitat. We designed CROM experiments with four treatments: no mussels and no sediment (W, negative control), no mussels and sediment (WS, positive control), mussels and no sediment (WM), and mussels and sediment (WMS). The experiments were performed at the condition of 18${\sim}$25 L $h^{-1}$ of inflow, mussel density of 486.1 indiv. $m^{-2}$, and temperatures between 15 and $22^{\circ}C$ for 13 consecutive days. Physicochemical and biological parameters were measured at daily (10:00 am) intervals after the mussel addition. Results indicated that mussel stockings without addition of sediment effectively removed sestons (suspended solids and chlorophyll-a) at nearly same level over 80 percentage of the control during the study, while there were no differences in removal activities of sestons between with and without sediment (P>0.5). Therefore, it clearly suggests that CROM system using A. woordiana has a strong potential to control the seston in surface water of eutrophic lake.

• Korean Journal of Ecology and Environment
• /
• v.39 no.4 s.118
• /
• pp.471-480
• /
• 2006

The field scale experiment was performed to examine the performance of the constructed wetland for nonpoint source (NPS) pollution loading reduction. Four sets (each set of 0.88 ha) of wetland (0.8 ha) and pond (0.08 ha) systems were used. Water flowing into the Seokmoon estuarine reservoir from the Dangjin stream was pumped into wetland systems. Water depth was maintained at 0.3-0.5 m and hydraulic retention time was managed to about 2-5 days; emergent plants were allowed to grow in the wetland. The wetland effluent concentrations of $BOD_5$, TSS, and T-N were higher in winter than in the growing season excepting the T-P, and effluent $BOD_5$ concentration was higher than influents in winter. Mass retention of T-N and T-P was stable throughout the year, whereas mass retention of $BOD_5$ and TSS was decreased in winter. $BOD_5$, TSS, T-N, and T-P performance of the experi-mental system was compared with the existing database (North American Treatment Wetland Database), and was within the range of general system performance. From the first-order analysis, T-P was virtually not temperature dependent, and $BOD_5$ and TSS were more temperature dependent than T-N. Overall, the wetland system was found to be an adequate alternative for treating polluted stream water with stable removal efficiency and recommended as a NPS control measures.

• Journal of Korean Society on Water Environment
• /
• v.29 no.3
• /
• pp.354-364
• /
• 2013

The performance of the stormwater wetlands can be significantly influenced by antecedent stormwater in storage at the commencement of a stormevent. As inflows are intermittent and stochastic in nature, the evaluation of the treatment efficiency of a stormwater wetland should be considered by runoff capture and water treatment characteristics during interevent periods. In this study, analytical probabilistic model is applied to identity runoff capture rate and treatment efficiency of the stormwater wetland. To achieve this, continuous rainfall data recorded in Busan for 31 years has been analyzed to derive the runoff capture rate, and 1st order kinetic decay constants ($k_V$, 1/d) are calculated from regression analysis to identify pollutants removal during interevent periods. The results show that about 60.9% of annual average runoff is captured through the stormwater wetland. The annual average treatment efficiencies of SS, BOD, COD, TN and TP is about 11.4, 8.9, 9.8, 4.3 and 9.6%, respectively. The analytical model has been compared with the numerical model and it shows that analytical model is valid. Performance evaluation methods developed in this study has the advantages of considering characteristics of rainfall-runoff, facility type and pollutant removal.

• Journal of environmental and Sanitary engineering
• /
• v.20 no.3 s.57
• /
• pp.36-43
• /
• 2005

Prior to the study of the sewage treatment methods, water quality for Gwangju sewage of fluent was investigated from January to December, 2004 for sewage water reuse. Monthly mean values of BOD, SS, turbidity, total phosphorus and color were 4.1 mg/L, 2.9 mg/L, 0.8 NTU, 1.3 mg/L, and 27 unit, respectively. Jar-test was performed to investigate the removal efficiency of pollutants under the coagulation conditions of fast mixing for 5 min, slow mixing for 15 min and precipitation for 1hr. Here, alum and polyaluminium chloride (PAC) were used as coagulants to reduce color, turbidity, total phosphorus (TP) and total organic carbon (TOC) in sewage effluents. The results showed that PAC gave better efficiency in removing turbidity and dissolved phosphorus than alum. It was also found from the relative molecular weight (RMW) distribution analysis that organic matter over 1,000 Dalton (Da) was easily removed by coagulation and subsequently MF treatment, while it was not effective for less than 500 Da. Based on tis result, Natural organic matter (NOM) with lower molecular weight (< 500 Da) may cause harmful disinfectant by-product (DBP) after chlorine treatment. Thus, activated carbon adsorption seems to be required for the complete removal of DBP in the hybrid system.

• Journal of Korean Society on Water Environment
• /
• v.18 no.4
• /
• pp.401-409
• /
• 2002

In this study, to evaluate the applicability of ORP and pH as process control parameters for an intermittent aeration process, a 200L/d bench-scale plant was installed and operated for 90 days. It was fed with synthetic wastewater which contained $COD_{Cr}$ : 400mg/L, TN : 40mg/L and TP : 7mg/L. ORP & pH were measured on-line and compared with the variation of nutrient concentrations. As the results, both of the ORP and pH were able to monitor successfully nitrification and denitrification. Bending-points on the ORP curve and peak points on the pH curve corresponded to the termination of nitrification and denitrification. For P uptake and release, pH was the best indicator for performance evaluation. The aerobic pH apex was appeared when P uptake was accomplished and there was a relationship between the P release and pH variation. But the pH curve needed filtering because there were many noises on it. In this study, the shape of the ORP & pH curves were varied as the operating conditions such as aeration rates and organic loads were changed. It allowed the operating states of biological systems to be effectively evaluated. If it is properly managed to show the bending points and peak points clearly, the on-line monitoring of ORP & pH will be a reliable and effective technique for process control of intermittent aeration processes.

• Journal of Korean Society of Water and Wastewater
• /
• v.21 no.6
• /
• pp.737-744
• /
• 2007

Recently, one of the most interesting topic in the field of wastewater treatment is the disposal of excess sludge. The new concept of excess sludge reduction with recirculation of solubilized sludge via effective microorganisms for cell disruption within the wastewater treatment process has been developed in this study. The alkalophiles for degradation of sludge cell wall were isolated as Exiguobacterium sp., which could be more effectively solubilized sludge in the anaerobic condition. The SCOD of solubilized excess sludge by Exiguobacterium sp. was up to about 2,000mg/L and average TN and TP concentration of solubilized component were 117mg/L and 58mg/L, respectively and C/N ratio was more than 17. To investigate the effects of solubilized sludge by alkalophiles on excess sludge reduction and nutrient removal efficiency, the pilot plant of $DF^{(S)}-MBR$ process, combined with membrane bioreactor and sludge solubilization tank, was operated. In the control run(without sludge solubilization), the daily sludge production was about 4.54 kgMLVSS/day. However, in the $DF^{(S)}-MBR$(with sludge solubilization), the daily sludge production was decreased to 1.39kgMLVSS/day. The effluent quality satisfied the effluent regulation in both cases. Furthermore, the $DF^{(S)}-MBR$ showed relatively better TN removal efficiency in spite of high influent loading. So we concluded that the solubilized excess sludge by alkalophiles was effectively degraded in the MBR process as the carbon source and 70% of sludge reduction efficiency can be achieved.

• Journal of Korean Society of Water and Wastewater
• /
• v.24 no.5
• /
• pp.629-639
• /
• 2010

To evaluate the performance of high rate coagulation system(HRCS) for CSOs treatment, fundamental function of lab scale HRCS has been tested by using the Jar tester and lab scale HRCS. The optimum pH dose by Streaming Current value was found in the range of 5.3~6.0 in Fe(III), and in the range of 5.8~6.6 in Al(III) and the optimum chemical dose were 0.44mM of $Al_2(SO_4)_3$ and 0.93mM of $FeCl_3$. The removal efficiencies at optimum $Al_2(SO_4)_3$ dose were 75%($TCOD_{Cr}$), 97%(TP), 95%(SS) and 96%(turbidity), respectively. And the removal efficiency of particles with less than $5{\mu}m$ of diameter was 70% and that of particles with higher than $5{\mu}m$ of diameter was 90%. The optimum alum dose in lab scale HRCS was 150mg/L, and the treatment efficiency was the best with addition of 1.0mg/L polymer. The effect of Micro sand addition was not clear, because the depth of the sediment tank in lab scale HRCS was not long enough. But the HRT of this lab scale HRCS was able to be shorten less then 7 minutes by adding the micro sand. The surface loading rates with respect to using different chemicals were 0.43m/h with alum only, 5.78m/h with alum and polymer and 6.22m/h with alum, polymer and micro sand. As a result, HRCS using coagulant, polymer and micro sand developed in this study was evaluated to be very effective for CSOs treatment.

• Journal of Korean Society of Water and Wastewater
• /
• v.29 no.3
• /
• pp.359-370
• /
• 2015

This study developed an up-flow wetland providing either an eco-friendly follow-up process of medium-sized public treatment facility for livestock manure or a non-point source pollution controller near livestock farms. The four bench-scale up-flow wetlands were operated with four different bed media sets. The removal efficiencies of the wetland effluent for CODCr, TN, TP, SS were 35.2 %, 29.5 %, 31.2 % and 52.2 % for set 1(Blank, without reed, with bio-ceramic), 40.6 %, 43.4 %, 42.2 % and 55.4 % for set 2(with bio-reed & without bio-ceramic), 45.2 %, 48.7 %, 46.6 % and 66.3 % for set 3(with bio-reed & bio-ceramic), 32.9 %, 27.3 %, 29.3 % and 54.1 % for Set 4(with reed & bio ceramic), respectively. The set 3 condition having a mixture of bio-reed and bio-ceramic showed the highest efficiency in the bench-scale evaluation. This study suggests a mixture of bio-reed and bio-ceramic as suitable bed media in the construction of artificial wetlands near livestock farms. Soils including the bed media were monitored during the evaluation for trace elements. Soil analysis results were satisfied with the Korean Soil Contamination Standard. This study showed that the up-flow constructed wetland was feasible to treat the effluent livestock wastewater treatment facility.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.47 no.1
• /
• pp.93-102
• /
• 2005

A prototype surface flow constructed wetland was built in the upstream area of Sihwa reclaimed tidal lands to improve the water quality of Lake Sihwa by treating severely polluted stream water. In this study, we monitored hydrology, macrophyte (Phragmites communis Trin,) growth, and water quality in the Banwol and Donghwa wetlands to evaluate their performance during the initial period after the completion of wetland construction, The average removal efficiency($\%$) in each wetland was relatively low compared with the performance data from the North America Wetland Treatment System Database (NADB), which mainly includes urban sewage-treatment wetlands. However, the average removal rates per unit area ($g/m^{2}/day$) were 0.72, 0.72 and 0.51 (BOD), 2,04, 2.46 and 0.70 (SS), 0.89, 0.43 and 1.09 (TN) and 0.02, 0.02 and 0.02 (TP) in the Banwol and Donghwa wetlands and NADB, respectively. The overall performance of the Banwol and Donghwa wetlands was within the expected range of the wetland system processes contributing the reduction of the pollutant load to Lake Sihwa during the initial period of wetland operation. Considering the low influent concentration, high hydraulic loading rate, and insufficient macrophyte growth since the wetland was constructed, better performance is expected if an improved operational scheme is adopted.