생태계에서 인산염은 중요한 영양물질이지만, 일정 농도 이상일 경우 부영양화의 원인이 된다. 본 연구는 수중 인산염의 제거효율 향상을 위해 Cu(Ⅱ)용액을 이용하여 분말활성탄의 표면개질을 진행하였으며, 회분식 실험을 통해 인산염의 흡착 특성을 분석하였다. SEM 분석을 통해 PAC-Cu 표면에 구리 기반의 결정을 보았고, 용출실험 결과 구리가 정량적으로 24 mg/g 용출된 것을 제시하였다. BET 분석결과 개질 후 비표면적과 기공 부피가 각각 7.53%, 8.66%로 유사하게 감소하였다. 제거 효율 실험에서 PAC-Cu는 PAC대비, 중성인 pH조건에서 최대 3.46배 높은 인산염 흡착능을 보였다. pH 실험에서 PAC의 경우 pH 6에서 최대 효율을 나타내고 있으나, PAC-Cu는 넓은 pH 범위(pH 5~8)에서 일정한 제거효율을 보였다. 등온흡착 모델링 결과, Langmuir와 Sip모델 적용했을 때 최대흡착량은 각각 52.3 mg/g과 126 mg/g으로 PAC의 9.48 mg/g과 31.6 mg/g보다 높은 값을 나타내고 있다. 반응속도실험의 경우, PAC-Cu와 PAC모두에서 30분 이내에서 모두 평형에 도달하였으나, PAC-Cu가 PFO 및 PSO 모델 적용시 높은 k값을 가진다.

초순수(UPW) 생산 공정에서는 이온과 유기물의 효과적인 제거가 필수적이며, 그 핵심 공정으로 역삼투(RO)가 활용된다. 본 연구에서는 다양한 RO 막 모듈의 성능을 평가하여 생산수 수질을 비교⋅분석하였다. 실험 결과, 모든 막에서 생산수 전기전도도(EC)는 거의 동일하게 나타나 염 투과 특성이 일정함을 확인하였다. 반면, 생산수 총유기탄소(TOC) 농도는 막 모듈 간 뚜렷한 차이가 관찰되어, 유기물 제거 효율이 막 모듈 특성에 크게 의존함을 보여주었다. 흥미롭게도, 원수의 농도가 높아질수록 생산수 TOC 품질이 개선되거나 저하되지 않는 경향을 나타냈으며, 이는 2차 RO 공정에서 높은 회수율을 유지하면서도 TOC 제거 효율을 저하시키지 않을 수 있음을 시사한다. 또한, 막 성능은 수 투과계수(A)와 염 투과계수(B)를 이용해 표준화하였으며, 이를 통해 막 간의 성능 비교가 가능함을 확인하였다. 분석 결과, 특히 B값이 낮은 막일수록 생산수 TOC를 더 효과적으로 감소시키는 우수한 성능을 보였다. 이러한 결과는 염 투과 성능이 비교적 균일한 반면, 유기물 제거 효율이 모듈 선택의 핵심 기준임을 강조한다. 따라서 A 및 B값을 활용한 표준화된 비교는 유기물 제거에 효과적인 막 모듈을 합리적이고 정량적으로 선택할 수 있는 근거를 제공하며, 초순수 제조 공정의 효율성과 신뢰성을 향상시킬 수 있음을 보여준다.

본 연구에서는 S시 소재의 하수처리장의 총인(TP) 처리 시설에서 수질 개선을 위해 적합한 응집제의 선정과 적용 방안을 검토하였다. 해당 시설에서는 17% 무기 고분자인 폴리알루미늄 클로라이드(PAC)를 이용한 화학적 처리법을 사용하고 있었다. 그러나 겨울철에는 17% PAC의 낮은 용해도와 염기성 부족으로 인해 반응성이 저하되고, 이로 인해 침전물과 응집제 공급라인의 막힘 문제가 발생하였다. 자테스트 시험 결과, 염기성이 높은 10% PAC가 고체-액체 분리와 침전 성능 면에서 우수하여 와류흐름용존공기부상법 (Swirling-flow dissolved air flotation)을 사용하는 대규모 TP 처리 시설에 적용하였다. 2019년부터 2021년까지는 17% PAC를 사용한 운영 데이터와, 2022년부터 2024년까지는 10% PAC로 변경된 데이터를 비교 분석하였다. PAC 10% 적용 후 약품 사용량은 감소하였으나, 응집제 단가가 상승하여 전체 약품비는 증가하는 경향을 보였다. 2021년 이후 유입수 TP 농도가 상승함에 따라 약품 사용량도 증가하였다. 본 연구는 고염기성 10% PAC가 기존 17% PAC 대비 수질 개선 및 안정성 향상에 효과적이며, 오염물질 제거 성능과 함께 운영 비용 측면에서도 유리함을 확인해 주었다.

이 연구의 목적은 염전에서 폐기되는 간수로 만든 담체의 비소 제거 특성을 연구한 것이다. 간수담체의 물리적 특성은 800 ~ 900℃에서 소성된 것을 사용하여 검토하였다. 비표면적과 흡수율은 각각 16.670 m2/g, 42.3%이었고 압축강도와 총 기공부피는 각각 28.3 kgf/cm2, 0.00818 cm2/g이었다. 간수담체의 화학적 조성은 SiO2가 55.3%이었고 특히, MgO가 19.2%로 매우 높은 농도로 존재하였다. 이런 결 과는 마그네슘 이온을 고농도로 포함하고 있는 간수의 영향을 받은 것으로 판단된다. 또한, X-Ray 회절 분석 결과, 간수담체는 Forsterite(Mg2SiO4)와 결정구조가 유사한 것으로 밝혀졌다. 간수담체는 제올라이트와 다양한 간수 용량으로 제조되었고 20% 간수로 만든 간수담체에서 비소 제거 효율이 최대화되었다. 또한, 수용액 중 간수담체의 용량이 40%일 때 90% 이상의 비소 제거 효율을 나타냈다. 간 수담체의 비소 제거 반응은 매우 빠르게 발생하였고 대부분의 비소 제거 반응이 수 시간 내에 끝났다. 회분식 실험을 통해서 간수담체의 비소 제거율에 미치는 pH 영향을 검토한 결과, 간수담체는 넓은 pH 범위(pH 5 ~ 10)에서도 높은 비소 제거 효율을 나타내었다.

This study evaluates the potential of various coagulants to enhance the efficiency of total phosphorus removal facilities in a sewage treatment plant. After analyzing the existing water quality conditions of the sewage treatment plant, the coagulant of poly aluminium chloride was experimentally applied to measure its effectiveness. In this process, the use of poly aluminium chloride and polymers in various ratios was explored to identify the optimal combination of coagulants. The experimental results showed that the a coagulants combination demonstrated higher treatment efficiency compared to exclusive use of large amounts of poly aluminium chloride methods. Particularly, the appropriate combination of poly aluminium chloride and polymers played a significant role. The optimal coagulant combination derived from the experiments was applied in a micro flotation method of real sewage treatment plant to evaluate its effectiveness. This study presents a new methodology that can contribute to enhancing the efficiency of sewage treatment processes and reducing environmental pollution. This research is expected to make an important contribution to improving to phosphorus remove efficiency of similar wastewater treatment plant and reducing the ecological impact from using coagulants in the future.

PURPOSES : Recently, air pollution due to fine particulate matter has been increasing in Korea. Nitrogen oxides (NOx) are particulate matter precursors significantly contributing to air pollution. Increasing efforts have been dedicated to NOx removal from air, since it is particularly harmful. Application of titanium dioxide (TiO2) for concrete road structures is a suitable alternative to remove NOx. As the photocatalytic reaction of TiO2 is the mechanism that eliminates NOx, the ultraviolet rays in sunlight and TiO2 in existing concrete structures need to be contacted for the reaction process. For the application of vertical concrete road structures such as retaining walls, side ditches, and barriers, a pressurized TiO2 fixation method has been developed considering the pressure and pressurization time. In this study, longterm serviceability and repeatability were investigated on concrete specimens applying the dynamic pressurized TiO2 fixation method. Additionally, the environmental hazards of nitrate adsorbed on TiO2 particles were evaluated. METHODS : Concrete specimens to simulate roadside vertical concrete structures were manufactured and used to evaluate the long-term serviceability and repeatability of the dynamic pressurized TiO2 fixation method. The NOx removal efficiency was measured using NOx evaluation equipment based on ISO 22197-1. In addition, the nitrate concentration was measured using a comprehensive water quality analyzer for evaluating environmental hazards. RESULTS : As the experiment to evaluate the NOx removal efficiency of the dynamic pressurized TiO2 fixation method progressed from one to seven cycles, the nitrate concentration increased from 2.35 mg/L to 3.06 mg/L, and the NOx removal efficiency decreased from 53% to 25%. After seven cycles of NOx removal efficiency evaluation, the average nitrate concentration was 3.06 mg/L. The nitrate concentration collected immediately after the NOx removal efficiency test for each cycle was in the range of 2.51 to 2.57 mg/L. By contrast, it was confirmed that the nitrate concentration was lowered to approximately 2.1 mg/L when the surface was washed with water. CONCLUSIONS : The NOx removal efficiency was maintained at over 25% even after seven cycles of NOx removal efficiency evaluation, securing long-term serviceability. In addition, the harmful effects on the environment and human health are insignificant, since the nitrate concentration was less than 10 mg/L, in accordance with domestic and foreign standards. Practical applicability of the pressurized TiO2 fixation method was established by evaluating the long-term serviceability, repeatability, and environmental hazards.

PURPOSES : The increase in particulate matter due to increased air pollutant emissions has become a significant social issue. According to the Ministry of Environment, air pollutants emitted from large-scale businesses in 2022 increased by 12.2% compared to the previous year, indicating that air pollution is accelerating owing to excessive industrialization. In this study, TiO2, which is used to reduce airborne particulate, was used. The TiO2 coating fixation and dynamic pressure coating-type TiO2 fixation methods were used to solve the material peeling phenomenon caused by gravity, which is a limitation when the TiO2 penetration method is applied to a vertical concrete structure along the road. The long-term durability and performance were analyzed through environmental resistance and NOx removal efficiency evaluation experiments. These analyses were then assessed by comparing the NOx removal efficiency with the dynamic pressure permeationtype TiO2 fixation method used in previous studies. METHODS : To evaluate the long-term durability and performance of the TiO2 coating fixation method and dynamic pressure coating TiO2 fixation method for vertical concrete structures, specimens were manufactured based on roadside vertical concrete structures. Environmental resistance tests such as the surface peeling resistance test (ASTM C 672) and freeze-thaw resistance test (KS F 2456) were conducted to evaluate the long-term durability. To evaluate the long-term performance, the NOx removal efficiency of TiO2 concrete owing to road surface deterioration during the environmental resistance test was evaluated using the NOx removal efficiency evaluation equipment based on the ISO 22197-1 standard. This evaluation was compared and analyzed using the dynamic pressure infiltration TiO2 fixation method. RESULTS : The long-term durability of the TiO2 coating fixation and dynamic pressure coating TiO2 fixation methods were evaluated using environmental resistance tests. During the surface peeling resistance test, the TiO2 material degraded and partially detached from the concrete. However, the NOx removal efficiency was ensured by the non-deteriorated and fixed TiO2 material. The long-term performance was confirmed through a freeze-thaw resistance test to evaluate the NOx removal efficiency after 300 cycles of surface deterioration. The results showed that when the TiO2 coating fixation and dynamic pressure infiltration TiO2 fixation methods were applied to vertical concrete structures, the durability of the structure was not compromised. In comparison to the dynamic pressure infiltration TiO2 fixation method, the NOx removal efficiency observed during the surface peeling resistance test was lower, while the freeze-thaw test exhibited notably higher removal efficiency. CONCLUSIONS : To solve the material peeling phenomenon caused by gravity, the long-term durability and performance were evaluated by applying the TiO2 coating fixation and dynamic pressurized coating TiO2 fixation methods to vertical concrete specimens. Long-term durability was confirmed through environmental resistance tests, and long-term utility was secured by measuring the NOx removal efficiency according to surface degradation. These findings show that implementing the TiO2 coating fixation method and dynamic pressure coating TiO2 fixation methods on-site effectively reduce NOx.

This study focused on using indirect filtration through riverbeds to produce high-quality drinking water. Data on water quality from a water intake facility(capacity 10,000 m3/day) and nearby rivers were collected over a three-year period. The average intake facility specifications were found to be a specific surface area of 58 balls/m2, a mean particle size of 24 mm, an inflow velocity of 2.2 cm/sec, and a burial depth of 5 m. The water quality improvement rate was assessed as grade Ia, surpassing the adjacent river’s water quality. Correlation analysis showed a weak correlation between opening ratio, Suspended Solid (SS), and Biochemical Oxygen Demand (BOD) compared to total coliforms and fecal coliforms. The correlation coefficient R value of SS was -0.614, BOD was –0.588, total coliforms -0.870, and fecal coliforms -0.958. The R value shows a negative value, which showed that the larger the opening rate, the lower the removal rate of water pollutants. The correlation coefficient R values according to the depth of burial were found to be BOD 0.914, SS-0.124, total coliforms 1.000, and fecal coliforms 0.866. The deeper the burial depth, the higher the removal rate of BOD and microbial groups.

Daechung Reservoir has been suffering from severe cyanobacterial blooming periodically due to the water pollutants from the watershed, especially nutrients from nonpoint sources. As a countermeasure, an artificial wetland was constructed to mitigate the pollutant load from the watershed by utilizing the vegetation. We investigated the water quality of the influent and outflow of the wetland during years 2014~2020 to evaluate the performance of pollutant removal through the wetland. Major pollutants (e.g. BOD, COD, SS, T-N, and T-P) were largely reduced during the retention in the wetland while nutrients removal was more efficient than that of organic matters. Pollutant removal efficiency for different inflow concentrations was also investigated to estimate the wetland’s capability as a way of managing nonpoint sources. The efficiency of water treatment was significantly higher when inflow concentrations were above 75th percentile for all pollutant, implying the wetland can be applied to the pre-treatment of high pollution load including initial rainfall runoff. Furthermore, the yearly variation of removal efficiency for seven years was analyzed to better understand long-term trends in water treatment of the wetland. The annual treatment efficiency of T-P was very high in the early stages of vegetation growth with high concentration of inflow water. However, it was confirmed that the concentration of inflow water decreased, vegetation stabilized, and the treatment efficiency gradually decreased as the soil was saturated. The findings of the study suggest that artificial wetlands can be an effective method for controlling harmful algal blooms by alleviating pollutant load from the tributaries of Daechung Reservoir.

PURPOSES : Advancements in science and technology caused by industrialization have led to an increase in particulate matter emissions and, consequently, severity of air pollution. Nitrogen oxide (NOx), which accounts for 58% of road transport pollutants, adversely affects both human health and the environment. A test-bed was constructed to determine NOx removal efficiency at the roadside. TiO2, a material used to reduce particulate matter, was used to remove NOx. It was applied to a vertical concrete structure using the dynamic pressurized penetration TiO2 fixation method, which can be easily applied to vertical concrete structures. This study was conducted to evaluate the NOx removal efficiency of the dynamic pressurized-penetration TiO2 fixation method in a test-bed under real roadside conditions. METHODS : A test-bed was constructed in order to determine the NOx removal efficiency using the dynamic pressurized penetration TiO2 fixation method on the roadside. The dynamic pressurized-penetration TiO2 fixation method was applied by installing a vertical concrete structure. NOx was injected into the test-bed using an exhaust gas generator. By installing a shading screen, the photocatalytic reaction of TiO2 was suppressed to a maximum concentration of 1000 ppb along the roadside. The removal efficiency was evaluated by measuring NOx concentrations. In addition, illuminance was measured using an illuminance meter. RESULTS : From the results of the analysis of the NOx removal efficiency in the test-bed which the dynamic pressurized type TiO2 fixation method was applied to, an average removal efficiency ranging from 18% to 40% was achieved, depending on the illuminance. Similarly, according to the results of the evaluation of the NO removal efficiency, an average of removal efficiency ranging from 20% to 62% was achieved. Thus, the NOx removal efficiency increased when the illuminance was high. CONCLUSIONS : From the results of the experiment conducted, the efficiency of NOx removal per unit volume was obtained according to the illuminance of TiO2 concrete along an actual road. Field applicability of the dynamic pressurized-penetration-type TiO2 fixation method to vertical concrete structures along roads was confirmed.

Most of the white fumes from the tenter process of a textile plant in an industrial complex are generated by water vapor and oil mist. While general water vapor disappears when the humidity is lowered, the white fume generated in the tenter process does not disappear and is continuously maintained, resulting in environmental problems and complaints. Efforts to reduce white fume are being conducted, but it is vitally important to develop a performance index that quantitatively calculates and deduces the degree by which white fume has been reduced, so that a tangible and visible result can be obtained in the performance evaluation of prevention facilities. In this study, the removal efficiency or performance of a general wet scrubber and a wet electrostatic precipitator (electrical fume collector, EFC) installed in the actual textile tenter process was analyzed by the light scattering method that can measure the concentration of particles up to a high level. The white fume removal efficiency of the EFC was 92%, much higher than the 17% removal efficiency of the general scrubber. In addition, the EFC was more effective in removing toluene, 1,1'- [oxybis(methylene)]bis- Benzene, and benzothiazole, which are the major substances generated from the textile tenter process, as well as complex odors. From these results, it was found that the light scattering method is one of the useful tools to evaluate the performance of white fume prevention facilities in the industrial field in terms of satisfying the urgent need for measurement and the ability to obtain a clear and precise result on site. This approach is meaningful in that real-time quantification is applicable more intuitively than the gravimetric method in assessing the fume removal performance as it can be observed with the naked eye.

PURPOSES : Recently, air pollution caused by particulate matter has been worsening. Among the substances generating particulate matter, NOx is the main precursor of particulate matter and is widely distributed in areas with a high volume of traffic. TiO2 has been used as a material for removing NOx through a chemical reaction as a photocatalyst. In this context, the reduction of NOx through TiO2 concrete is proposed. However, the research on the surface deterioration on the performance of TiO2 concrete is not documented yet. Therefore, the objective of this study was to evaluate the long-term durability and NOx removal efficiency of TiO2 concrete by considering the concrete surface deterioration. METHODS : Freezing–thawing resistance test (KS F 2456) and scaling test (ASTM C 672) were performed to investigate the variation in the TiO2 penetration distribution and NOx removal efficiency of TiO2 concrete corresponding to surface deterioration. The long-term durability of TiO2 concrete was evaluated through an environmental resistance test and changes in TiO2 penetration depth and distribution characteristics. In addition, the NOx removal efficiency of TiO2 concrete was evaluated as surface deterioration occurs. RESULTS : As a result of the freeze–thawing resistance test, a relative dynamic elastic modulus of more than 80 % was detected. In addition, a TiO2 penetration depth of 0.3 mm, NOx removal efficiency of 11.2 %, and a 30 % of TiO2 surface prediction mass ratio were achieved after 300 cycles. As a result of visual observation of the scaling test, “0, no scaling” was secured. After 50 cycles of scaling test, the TiO2 penetration depth, NOx removal efficiency, and TiO2 surface prediction mass ratio were 0.3 mm, 36.3 %, and 63 %, respectively. Through the results of the environmental resistance test, the excellent long-term durability and NOx removal efficiency of TiO2 concrete were confirmed. CONCLUSIONS : As a result of the experiment, long-term durability and NOx removal efficiency of TiO2 concrete were secured. The application of TiO2 concrete can be a good alternative with long-term performance and durability.