• 한국환경과학회지
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• 제10권2호
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• pp.113-117
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• 2001

This study was conducted to investigate the effect of the prechlorination on algal removal by application of a varying amount of different coagulants, such as LAC, PAC, PACS following the process of coagulation and sedimentation of algae in the Nakdong River. The samples used as a source for the raw water of the Nakdong River were collected from the D Water Purification Plant in Taegu city. With the application of the process of prechlorination, the removal rate of the algae was increased from 10~25% for Synedra spp., 20~35% for diatoms and 4~17% for turbidity. Generally, the removal rate of the algae was increased with the increase of the concentration of the coagulants. The PAC and PACS showed 5% higher removal rate for turbidity as compared to the LAS. On the hand, LAS showed 12% higher removal rate for Synedra spp. as compared to the PAC and PACS. The variations in the removal rate of diatoms with the change of coagulant were not significant. In conclusion, the application of LAS, polymeric coagulant and chlorination for at least 20 minutes could be considered as a reliable treatment process for the removal of source water containing a variety of algae.

• 생태와환경
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• 제42권3호
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• pp.404-406
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• 2009

본 연구노트는 우리나라의 원천기술로서 개발된 녹조제거용 특수선박을 소개하고자 하였다. 녹조제거용 특수선박은 +자형으로서 크게 선박 본체와 탈부착 가능한 보조체로 구성되어 있다. 선박의 특징은 초경량 및 저홀수이다. 주요 세부장치는 흡입장치, 집수장치, 여과장치 및 수집장치의 4가지로 구성되어 있다. 이 중에서 여과장치는 스크린 필터(망목크기 30${\mu}m$)를 사용하였고 압축에어 분사작용에 의해 물과 녹조를 순수 분리 및 제거할 수 있다. 농축된 녹조입자의 함수율은 85%이었다. 최종적으로 녹조와 분리된 물은 하천과 저수지의 공공수역으로 배출된다. Chlorophyll-$\alpha$ 농도로 비교한 제거효율은 약 57% (유입수 83.2 ${\mu}g\;L^{-1}$, 배출수 35.8 ${\mu}g\;L^{-1}$)이었고, 향후 녹조제거장치의 효율성 제고와 기술적 향상을 위해 다양한 조건(조류 생물량, 유량 등)에서 효과분석을 수행할 필요가 있다. 다발성 녹조발생 우심지역을 효과적으로 관리하고, 저수지 하류수역으로 확산을 방지하는 녹조현상의 사전예방체제 구축에 기여하고자 하였다.

• 대한환경공학회지
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• 제37권10호
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• pp.563-572
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• 2015

본 연구는 영산강 수계 승촌보에서 시행되었던 조류배제를 위한 다기능보 운영 사례를 대상으로, 3차원 모델링을 통한 효과 분석을 목적으로 수행되었다. 2013년 5월 영산강 승촌보 구간에서 녹조류 Eudorina sp.가 대량 발생하였으며, 집적된 녹조의 배제를 위하여 서로 다른 방법으로 두 차례에 걸쳐 플러싱 방류를 시행하였다. 조류 발생의 공간적 분포에 대한 상세분석과 이해를 위해 고해상도의 3차원 모형 ELCOM-CAEDYM을 적용하여 1개월 동안의 수질과 chl-a 분포를 모의하였다. 모델링 결과 ELCOM-CAEDYM 모형은 실제 조류의 발생 패턴을 우수하게 모의하였으며, 저비용으로 조류 발생에 대한 고해상도의 공간적인 데이터를 재생산 하는데 적합할 것으로 판단되었다. 모델링 결과를 이용하여 두 가지 방법의 플러싱 방류 CASE를 분석한 결과, 가동보를 이용하여 플러싱 방류를 실시한 CASE1의 경우 서창교~황룡강 합류지점에 발생하였던 조류는 가동보 운영에 의하여 빠르게 하류로 이동되었으나, 이후 방류량이 감소하면서 보 내에 잔류하였던 것으로 분석되었다. 반면, 소수력발전을 중단하고 고정보를 통한 월류를 실시한 CASE2는 비교적 배제 효과가 크게 나타나 대부분의 조류가 플러싱되어 감소된 것을 관측 자료와 모델링 결과로서 확인할 수 있었다.

• 상하수도학회지
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• 제33권1호
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• pp.9-16
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• 2019

The algal blooms in stagnant streams and lakes have caused many problems. Excessive algae leads to disturbance of ecosystem and overload of water treatment processes. Therefore, phosphorus(P), source of algal blooms, should be controlled. In this study, a filtration trench has been developed to convert dissolved phosphorus into hydroxyapatite(HAP) so that it could be crystallized on the surface of 'phosphorus removal granular material'; and residual particulate phosphorus could be removed by additional precipitation and filtration. The front and rear parts of filtration trench consisted of 'phosphorus removal granular material contact bed' and 'limestone filtration bed', respectively. As a result of the column test using phosphorus removal granular material and limestone serially, $PO_4-P$ was removed more than 90% when EBCT(empty bed contact time) of the contact bed was over 20 minutes; and T-P represented 60% of removal efficiency when total EBCT was over 1.5 hours. The results of column tests to figure out the sedimentation characteristics showed that more than 90% of particulate phosphorus could be removed within 24 hours. It was necessary to optimize the filtration part in order to increase removal efficiency of T-P additionally. Also, it was confirmed through the simulation of Visual MINTEQ that most of particulate phosphorus in the column tests is the form of HAP. Based on the results of the study, it could be suggested that the design parameters are over 0.5 hour of EBCT for phosphorus removal granular material contact bed and over 1.5 hours of EBCT for limestone filtration bed.

• Membrane and Water Treatment
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• 제9권3호
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• pp.173-179
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• 2018

Microcystin-LR, one of algal toxins induced by the eutrophication of a reservoir, is known to be harmful to human by adversely affecting our liver and brain. Hypochlorous acid is very efficient to remove Microcystin-LR in a clear well. The previous researches showed that CT, pH and temperature affected removal rate in batch tests. It was noted that hydrodynamic properties of clear well could also influence its removal rate. A mathematical model was built using an axial dispersion reactor model and software was used to simulate the removal rate. The model consisted of the second order differential equations including dispersion, convection, Microcystin-LR reaction with chlorine. Kinetic constants were obtained through batch tests with chlorine. They were $0.430{\times}10^{-3}L/mg/sec$ and $0.143{\times}10^{-3}L/mg/sec$ for pH 7.0 and 8.1, respectively. The axial dispersion reactor model was shown to be useful for the numerical model through conservative tracer tests. The numerical model successfully estimated the removal rate of Microcyctin-LR in a clear well. Numerical simulations showed that a small dispersion number, low pH and long hydraulic retention time were critical for higher removal rate with same chlorine dosage. This model could be used to optimize the operation of a clear well during an eutrophication season.

• 상하수도학회지
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• 제18권2호
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• pp.208-214
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• 2004

Dissolved air flotation (DAF) is an effective solid/liquid separation process for low density floc particles such as algal, color-alum and clay-alum flocs produced from low turbidity water. The removal of taste and odor-causing organics (2-mthylisoboneol and geosmin) originating from algae in drinking water is a local and worldwide concern. Although DAF has been effectively applied for the removal of suspended solid, its application for the treatment of dissolved organic carbon is very limited. In this study, a new hybrid system consisting of adsorption and DAF processes was introduced for the simultaneous removal of algae and taste and odor-causing organics. Powdered activated carbon (PAC) was used as an adsorbent. In this proposed system, the major concern of eliminating the spent PAC from the system was also addressed. It was found that zeta potential of algae and PAC was increased with coagulant dosage, and the removal efficiency in DAF was also enhanced up to 90~95% under the given experimental conditions. Based on this study, the hybrid process was found to be a promising technology for the simultaneous removal of algae and dissolved organic pollutants.

• Environmental Engineering Research
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• 제22권1호
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• pp.1-11
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• 2017

One of the most threatening consequences of eutrophic freshwater reservoirs is algal blooming which typically occur after the long a mega drought or/and irregular rainfall under influence of climate change. The long-term experiences of chemical treatment are known as a most practical effort to reduce health concerns from human exposure of harmful cyanobacteria as well as to preserve ultimate freshwater resources. Even though these conventional chemical treatment methods do not completely solve the algal residue problem in water treatment plant or directly in the water bodies, they still have big advantages as fast and efficient removal process of cyanobacteria due to cheaper, easier to manage. This review summarizes their chemical treatment scenarios of the representative coagulants, pre-oxidants and algaecides composed to chemical compounds which immediately may help to manage severe cyanobacteria blooms in the summer seasons.

• ALGAE
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• 제31권3호
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• pp.189-204
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• 2016

Microalgal bioremediation of CO₂, nutrients, endocrine disruptors, hydrocarbons, pesticides, and cyanide compounds have evaluated comprehensively. Microalgal mitigation of nutrients originated from municipal wastewaters, surface waters, and livestock wastewaters has shown great applicability. Algal utilization on secondary and tertiary treatment processes might provide unique and elegant solution on the removing of substances originated from various sources. Microalgae have displayed 3 growth regimes (autotrophic, heterotrophic, and mixotrophic) through which different organic and inorganic substances are being utilized for growth and production of different metabolites. There are still some technology challenges requiring innovative solutions. Strain selection investigation should be directed towards identification of algal that are extremophiles. Understanding and manipulation of metabolic pathways of algae will possible unfold solution to utilization of algae for mitigation of dissolve organic nitrogen in wastewaters.

• 한국물환경학회지
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• 제33권1호
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• pp.8-14
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• 2017

Microcystis aeruginosa (M. aeruginosa) is a cyanobacterium species that can form harmful algal blooms in freshwater bodies worldwide. The use of pine needle extract (PNE) to control nuisance algae by allelopathic inhibition will be environmentally friendly and promising. PNE removed successfully upto 98% of M. aeruginosa at the following optimal conditions: pH 7, $25^{\circ}C$ of temperature, 100 rpm of mixing rate, 5 min of mixing time. These results was indicated that the amount of 1 g/L PNE was removed 1g dryweight/L of M. aeruginosa. The kinetic data showed substrate inhibition kinetics and maximum growth rate was obtained when the M. aeruginosa was grown in medium containing 0.5 g/L of initial concentration of PNE. Different substrate inhibition models were fitted to the kinetic data and found the Luong model was best. The model predicted kinetic parameters were in agreement with the experimental findings. The natural extract, PNE, can be a promising inhibition due to its high efficiency and low dose requirements.

• ALGAE
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• 제19권1호
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• pp.7-14
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• 2004

Blue-Min was initially developed as an adsorbent for harmful gas removal and recently improved to apply to livestock, agriculture and aquaculture as an assistant feed. In the Blue-Min treatment, growth of harmful algae (Cochlodinium polykrikoides and the others causing the red-tide in the ocean) were inhibited below 10% in comparison with control and coagulation removal of harmful alge with Blue-Min treatment was more efficient than that of yellow loess treatment. It would be expected that the Ble-Min can be useful for the extirpator against the red-tide organisms and restrain the toxic algal growth around the fish aquaculture using the assistant feed. Recently, its utility has become to be diverse as it was revealed that aquaculture productivity increase by its application and, in addition, that it improve the water quality or sediment conditions in the aquaculture of Chinese White Shrimp. When Blue-Min was treated with the proper dose, the growth inhibition of Microcystis aeruginosa and lsochrysis galbana, which are typical red-tide organisms in freshwaters and food organisms in aquaculture, respectively, were less than that of marine red-tide organisms, while their growth slightly increased with low concentration treatiment. In addition, polyunsaturated fatty acids (PUFA) content of I. galbana slightly increase with the Blue-Min treatment. Through our research, the Blue-Min has diverse and comples function against various biological organisms and is proved as a biological activator or depressor.