국내 Y정수처리시설에 20-40 m3/m2/h의 표면부하율을 갖는 고속 용존공기부상공정을 도입하였다. 우선, 용존공기부상공정과 입상활성탄 공정이 결합된 반응기를 일처리용량 500 m3/day의 조건으로 운전하였다. 운전결과는 두 공정이 원수내 탁도, 조류, 지오스민, 2-MIB를 감소시킬 수 있음을 증명하였다. 도출된 최적 설계요소를 활용하여 현장규모의 공정(5,000 m3/day)에 용존공기부상공정을 도입하였다. 여름철 56일간 조류와 탁도 제거율을 평가하였다. 처리수 내 조류의 개체수는 20-30 cells/mL 이하로 유지되었으며, 조류 제거효율은 80-89%를 기록하였다. 침전법 및 용존공기부상공정 처리수질의 탁도 제거효율을 비교한 결과 평균 탁도 제거효율은 77%를 나타냈다. 이러한 결과들은 고속 용존공기부상공정이 여름철 음용수의 탁도 및 조류와 같은 저밀도 고형물을 제거하는데 유의미한 방법임을 나타냈으며, GAC는 맛･냄새를 유발하는 화합물(지오스민, 2-MIB)를 제거할 수 있는 공정 옵션인 것을 확인하였다.

본 실험에서는 실제 원수와 모사 원수를 이용하여 유기막(PES, PVDF 및 PTFE)을 이용하여 재질에 따른 막오염 특성을 분석하고자 하였다. 먼저 원수를 운전압력 1kgf/cm2로 여과하였다. 재질별 소요된 여과 시간은 약 5분, 약 13분, 약 17분으로 각각 나타났다. 또한 모사 원수 실험을 진행하였고, 원수 실험과 동일한 결과를 나타냈다. Jucker 와 Clark(1994)에 따르면 소수성 재질의 막이 유기물 흡착에 의한 Flux 감소가 크다고 보고하였고, 본 실험에서도 소수성 재질의 막이 높은 Flux 감소율을 나타났다. 실험 결과를 통해 막 재질 특성이 조류 유입에 따른 Flux 감소율에 영향을 미치는 것을 확인하였다. 본 연구는 환경부의 “환경정책기반공공기술개발사업”으로 지원받은 과제입니다.

In recent years there have been large increases in the hydraulic loading rates used to design dissolved air flotation (DAF) facilities for drinking water applications. High rate DAF processes are now available at loading rates of 20 to 40 m3/m2·h. This research evaluated dissolved air flotation as a separation method for algae and organic compounds from water treatment plants. During the service period of 2016. 5. to 2017. 6., DAF pilot plants (500 m3/day) process has shown a constantly sound performance for the treatment of raw water, yielding a significantly low level of turbidity (DAF treated water, 0.21～1.56 NTU). As a result of analyzing the algae cell counts in the influent source, it was expressed at 100-120 cells/mL. In DAF treated water, the removal efficient of alge cell counts was found to be upto 90%. The stable turbidity and algae removal were confirmed by operating the high rate DAF process under the condition of the surface loading rate of 30 m3/m2·hr.

This study was conducted to estimate the removal efficiency of algae by a mechanical Screw Brush Cone Filter in a lake. The device used a stainless steel cone-shaped filter with a screw brush. The ability of the developed device to remove algae larger than 20μm in Lake ChaSa, Gwangyang city was tested from August to September 2014. The results show that the removal rates for chlorophyll-a, suspended solids and volatile suspended solids were 44-87%(mean 61%), 35-54%(mean 40%), and 37-46%(mean 43%), respectively. This study also discusses equipment and device operation costs and device application problems, and suggests in situ. solutions to these problems.

After identifying species by collecting the suspended and attached algae mat inhabiting in the slow sand-filter, Spirogyra sp., Mougeotia sp. and Closterium sp. were main green algae and Synedra sp. was diatom algae. Among them green algae Spirogyra sp. was dominant species. A result of observing the life mode of apple snail for a month after introducing into the slow sand-filter, apple snail eggs were discovered on the filter walls 2 weeks after introducing, 4 weeks later lots of eggs were observed all of the slow sand-filter walls, it means there is no problem for apple snail to live in the slow sand-filter. The observation result for algae removal potential by introduced apple snail after 2 months later, slow sand-filter where apple snail were introduced, a few algal mat were observed. On the other hand, no introduced apple snail into the slow sand-filter, lots of suspended algal mats were formed in the water and attached algal mats on the sand surface as well, these algal mat induced much of operating problems.

The blue-green algae which caused odor problem in the tap water are difficult to precipitate in sedimentation basin and clogged the filter void rapidly. The studies of this paper were not only oxidation, coagulation and sedimentation processes for effectively removing blue-green algae but yellow clay and polyamine for verification as coagulants aids. The results of this research are summarized as follows: Higher ozone dose(C) and longer contact time(T) were needed for a high degree of removing blue-green algae efficiency. the removal rate of blue-green algae was proportional to the C×T value. The removal percent of chlorophyll-a by sedimentation and filter without pre-ozonation was about 75% but 1 mg/L pre-ozonation could increase the removal percent of chlorophyll-a to 99% and more pre-ozonation could remove completely. Though the removal efficiency of turbidity could increased by high dose of chlorination, the dissolved organic carbon was increased. More chlorine dose from 4 to 10 mg/L dissolved organic carbon was decreased. Using yellow clay as coagulant aids increased density of floc so the settling velocity of floc become rising but polyamine could not increase settling velocity of floc though it could formated large floc.

This study was carried out to evaluate the pollutant removal efficiencies of the advanced drinking water treatment using ozonation process. For raw water, Nakdong River was used. By conducting batch test of ozonation, the following results were obtained. When ozone dosage of 5 mg/ℓ was used, ozone transfer and utilization efficiencies of the ozonation were 94 to 92%, respectively. Removal efficiencies of single VOC compound or mixed VOC compounds in the raw water were 80% to 90% by the ozonation with 2 mg/ℓ dosage and 10 minutes contact time. Removal efficiencies of ABS by the ozonation with 1 mg/ℓ, 3 mg/ℓ dosage and 20 minutes contact time were 83% to 96% , respectively. Almost 67% of chlorophyll-a at the concentration of 38.4㎍/ℓ was removed by ozonation at ozone dosage of 1 ㎎/ℓ for 20 min. Considering the efficiency of ozone utilization and water treatment, the most effective ozonation could be obtained with high ozone dosage and short contact time.

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.

HRP(high rate pond) which had kept the manufactured clay of 3㎝-thickness as benthic clay in reactor and the 6 flat-blade turbine as impeller for agitation was named HRASP(high rate algae stabilization pond). And the experiment for treatment of artificial synthesis wastewater containing COD : 300㎎/ℓ. , NH3-N : 30㎎/ℓ, T-P : 9㎎/ℓ. as nutrients was been performed successfully. This reactor was been operated under conditions : 24 hrs.-irradiation and water temperature, 25℃ and pH 7 and agitation velocity, 15, 30, 45rpm and the effect of agitation velocity on algal bioaccumulation of nutrients was been studied with view point of fluid dynamics. The next followings could be obtained as results. 1. The agitation with a turbine impeller blade in HRASP makes clay particle indicate superior suspension effect by means of forming of excellent curl/shear flow in reactor. 2. The excessive suspension of clay particle which is created at 45rpm as rotation velocity of impeller blade of turbine disturbs the light penetration and algal photosynthesis reaction. 3. Efficiencies for removal of nutrients come out as COD : 93.9%∼94.3%, (NH3-N + NO3-N) : 81.9%-99.0%, T-P : 46.8%-53.6%. 4. Kuo values of K1 for algal growth come out seperately as 15rpm : 1.876×10-2, 30rpm : 4.618×10-3. 5. Kuo values of K2 for removal of N, P come out seperately as 15rpm : 8.403×10-1 and 1.397×10-1, 30rpm : 4.823×10-1 and 2.052×10-1. 6. It can be guessed easily that the excessive agitation can inhibit the algal and bacterial symbiotic reaction if it is considered that micro organism' sense to preservation of life is relied on natural function of metabolism. Therefore the studies for this matter should be followed continuously.

This study was performed to determine the optimum coagulant dosing for effective treatment of raw water in Chinyang lake. Removal rates of algae and characteristics of the water according to coagulants dosage were investigated by treatment with Microcystis aeruginosa, which is a kind of blue-green algae, to the raw water below 5NTU. The coagulants dosage for maximum removal rate of algae were 30 ㎎/ℓ of Alum, 30 ㎎/ℓ of PAC and 10 ㎎/ℓ of PACS, respectively. The removal rate of algae in 30 ㎎/ℓ of PAC was highest as 85% compared with the other treatments. At the point of maximum removal rate of algae, the removal rates of turbidity were 34%, 66% and 22% in Alum, PAC and PACS, respectively. Residual Al was decreased depend upon decreasing turbidity in water by treatment of Alum or PAC, but decreased depend upon increasing turbidity in water by treatment of PACS. The removal rate of Mn2+ in water was high in the order of Alum, PAC and PACS treatment. And Fe2+ in water was not changed by treatment of these coagulants. Particle numbers distributions according to the particle size of suspended solids that were not precipitated at 8 min. of settling time after treatment of coagulants dosage for the maximum removal rate of algae were investigated. Most of the particle sizes were below 30 ㎛ and particle numbers distributions below 10 ㎛ were 64%, 56% and 66% by treatment of Alum, PAC and PACS, respectively. Zeta potential was in the range of -6.1∼-9.7 mV at optimum coagulants dosage for algae removal.

The pilot plant had been made so as to be an association system from the various items managed to have degrees of efficiency and it have been done to consider the experimental result with irradiance period and pH influence of all major things to treatment function of Waste Stabilization Pond. The results are as following. The attained results for continuous & cyclic irradiance 1. 24L.-reactor was prior to 12L.-12D.-reactor on oxygen generation & algal production ability. 2. 24L.-reactor was prior to 12L.-12D.-reactor on nutrients removal efficiency. 3. In 24L.-reactor it maintained 5 ㎎/L∼6 ㎎/L, DO concent. enough to a fish`s survival. The attained results for pH condition 1. Oxygen generation & algal production in pH 4-reactor were higher than those in pH 10-reactor. 2. The acidic condition at pH 4 and alkalic condition at pH 10 did not so much affect an algal growth and nutrients removal. The attained results for whole 1. In view of the results appeared as [(NH_3-N)+(NO_3-N)] removal efficiency, 89.1%∼93.9% and PO_4-P removal efficiency, 34.3%∼83.7% & COD removal efficiency, 88.5%∼93.9%, It is possible to treat the wastewater with starch and pH which have been known as thedifficult problem. 2. At the point of non using methanol to nitrificate NO_3-N, the nutrients removal method by using an algal growth is the most economical method in the whole nutrients removal methods. 3. The nutrients removal method by using an algal growth contributes to natural ecosystem. 4. The nutrients removal method by using an algal growth is excellant in the prevention against the eutrophication.