In this paper, the performance of a synthetic fiber filter aimed at high-speed operation and dosed with different coagulants or filter aids was investigated. Without a coagulant, the filter efficiency was about 62% which was greatly enhanced when three types of coagulants namely PAC, Alum, and FeCl3 were used. Among the coagulants tested, PAC was the most effective, giving 91% filter efficiency, followed by Alum with 90%, and FeCl3 with 78%. PAC worked effectively at a very small range of dose, but Alum was relatively effective in a wide range of concentration. Compared with PAC and Alum, FeCl3 provided more or less contant efficiency regardless of its dose but gave the poorest filter efficiency. Moreover, as the inflow turbidity increased, headloss increased and the efficiency decreased at any dose and type of coagulant. The headloss recorded in this particular synthetic fiber filter is not significant as compared to that observed in typical granular filters. The recovery of solids estimated after filter cleaning was about 80% for both PAC and Alum, but poorer at 72% in the case of FeCl3 due to the heavy and large floc characteristics. The recurrence of filter efficiency verified through repetitive filter runs was found to be satisfactory.

A membrane bioreactor by sequentially alternating the inflow and by applying a two-stage coagulation control based on pre-coagulation was evaluated in terms of phosphorus removal efficiency and cost-savings. The MBR consisted of two identical alternative reaction tanks, followed by aerobic, anoxic and membrane tanks, where the wastewater and the internal return sludge alternatively flowed into each alternative reaction tank at every 2 hours. In the batch-operated alternative reaction tank, the initial concentration of nitrate rapidly decreased from 2.3 to 0.4 mg/L for only 20 minutes after stopping the inflow, followed by substantial release of phosphorus up to 4 mg/L under anaerobic condition. Jar test showed that the minimum alum doses to reduce the initial PO4-P below 0.2 mg/L were 2 and 9 mol-Al/mol-P in the wastewater and the activated sludge from the membrane tank, respectively. It implies that a pre-coagulation in influent is more cost-efficient for phosphorus removal than the coagulation in the bioreactor. On the result of NUR test, there were little difference in terms of denitrification rate and contents of readily biodegradable COD between raw wastewater and pre-coagulated wastewater. When adding alum into the aerobic tank, alum doses above 26 mg/L as Al2O3 caused inhibitory effects on ammonia oxidation. Using the two-stage coagulation control based on pre-coagulation, the P concentration in the MBR effluent was kept below 0.2 mg/L with the alum of 2.7 mg/L as Al2O3, which was much lower than 5.1∼7.4 mg/L as Al2O3 required for typical wastewater treatment plants. During the long-term operation of MBR, there was no change of the TMP increase rate before and after alum addition.

Nanosized and aggregated Y2O3:Eu Red phosphors were prepared by template method from metal salt impregnated into crystalline cellulose. The particle size and photoluminescent property of Y2O3:Eu red phosphors were controlled by variation of the calcination temperature and time. Dispersed nanosol was also obtained from the aggregated Y2O3:Eu Red phosphor under bead mill wet process. The dispersion property of the Y2O3:Eu nanosol was optimized by controlling the bead size, bead content ratio and milling time. The median particle size (D50) of Y2O3:Eu nanosol was found to be around 100 nm, and to be below 90 nm after centrifuging. In spite of the low photoluminescent properties of Y2O3:Eu nanosol, it was observed that the photoluminescent property recovered after re-calcination. The dispersion and photoluminescent properties of Y2O3:Eu nanosol were investigated using a particle size analyzer, FE-SEM, and a fluorescence spectrometer.

In the coagulation/sedimentation (C/S) process of the water treatment process, the inflow of massive algal bloom causes many problems including fouling of filter media. This study was conducted to find out the way to remove the algae’s harmful effects by addition of pre-treatment prior to C/S process. Many Jar-tests were conducted such as ① ACF (Algae Coagulation·Flotation) process using natural algae coagulant (Water Health®), ② ACF + C/S process and ③ C/S process with a variety of conditions using cultured algae. The average values of turbidity were ① 0.42 NTU for ACF process, ② 0.13 NTU for ACF + C/S process and ③ 0.25 NTU for C/S process. It was shown that the treatment efficiency of ACF process could get low turbidity results, and ACF + C/S process could achieve more efficient results than those of C/S process. Any negative effects of ACF process to the efficiency of C/S process were not observed in ACF + C/S process. In order to reduce the unfavorable effects of algae, it was found out that the introduction of ACF process in the forms of ① ACF or ② ACF + C/S could be one of the effective and alternative solutions.

Modified coagulants were investigated for the removal of phosphorus from secondary effluent of wastewater treatment. The modified coagulants were prepared by mixing alkali earth metal ions such as calcium and magnesium. The basicity of a coagulant influenced on the removal of phosphorus, and coagulants with basicity of 5.9% showed a better removal of total phosphorus than that of 38.5%. Also, coagulants with alkali earth metals enhanced the performance of coagulation by 10% and resulted in 67.1% for total phosphorus removal. Moreover, the removal of suspended solids and chemical oxygen demand was improved using coagulants with low basicity and earth metal ions. Results of this study demonstrated that the use of coagulants with low basicity, and calcium and magnesium ions is recommended to improve wastewater effluent quality.

Control degree and property changes of dissolved organic matter (DOM) were conducted by coagulation of chemical treatment for 2 sewage treatment plants with different technical methods. As the result, SUVA value of the second treated water (supernatant of the second settling pond after biological treatment) was increased and DOC was reduced in comparison with supplied raw water. And, SUVA value and DOC were reduced by coagulation after coagulation treatment of the second treated water. Properties of dissolved organic matter for 2 sewage treatment plants's DOC were divided. As the result, there was lots of hydrophilic component with hydrophilicity in case of plant A. In case of the second treated water, Plant A showed fulvic acid with little molecular weight was reduced among the hydrophobic component with hydrophobicity, but numic acide with lots of molecular weight was increased. However, in case of plant B, both fulvic acid with little molecular weight and humic acid with lots of molecular weight were increased among the hydrophobic components with hydrophilicity. Before the operation of phosphorus facility, properties of dissolved organic matter after biodegradation with effluent water showed hydrophilic components were reduced and hydrophobic components were increased. However, after coagulation treatment of the second treated water, hydrophilic components and hydrophobic components were outstandingly decreased or increased. During the biodegradation after coagulation treatment, hydrophilic components were significantly decreased and hydrophobic components were increased.

Although microalgae are considered as a promising feedstock for biofuels, cost-efficient harvesting of microalgae needs to be significantly improved. In this study, the use of electro coagulation as a more rapid flocculation method for harvesting a freshwater (Scenedesmus dimorphus) microalgae species was evaluated. The results showed that, electro coagulation was shown to be more efficient using an aluminum anode than using an iron anode. And optimum conditions of electro coagulation for harvesting Scenedesmus dimorphus were found. The optimum stirring speed was 100 rpm and optimum pH was 5. Furthermore, the current density which the fastest and highest recovery efficiency is achieved at 30 A/m2, while the highest energy efficiency was achieved at 10 A/m2. A the rapid and high recovery efficiency indicate that electro coagulation is a particularly attractive technology for harvesting microalgae.

복지생태계사업은 주민의 참여, 관계, 연대, 협력을 통하여 복지공동체를 구축해가는 전통적인 지역사회조직사업이다. 복지생태계사업의 성과는 주민들간의 응집력 형성과 지역사회 네트워크 활동의 확대로 이를 통해 마을의 변화가 나타나는 것이다. S복지재단 에서 지원한 복지생태계 구축 사업 중 3개 지역의 마을살이를 대상으로 주민들을 조직하는 비공식 조직들과의 네트워크 형성 정도를 2013년 및 2014년에 걸쳐 조사하였다. 본 연구를 통하여 3개 지역 모두 주민 중심의 비공식 네트워크의 성장이 나타났으며, 그 유형은 초기 성장의 모습이었다. 앞으로 마을의 강점을 토대로 주민들의 지역사회조직의 수준을 성장시키고, 협력적 관계 구축을 통한 공식적인 네트워크를 활성화시킬 수 있도록 발전시켜야 할 것이다.

This study aims to analyze the aspect of coherence realization of narrative discourse of female marriage immigrants. Considering that discourse structure and cohesive devices are engaged in the coherence of discourse, this study attempts to examine the aspect of structure development of narrative discourse and the utilization of reference and conjunction. The participants in the study are intermediate and advanced-level female marriage immigrants. The analysis results of this study can be summarized as follows: (1) the female marriage immigrants selectively contained [abstract] and [evaluation] while essentially containing [setting], [complicating action], [resolution] when comprising narratives; the coherence of discourse was found to be disrupted due to insertion of extraneous contents, lack of information, excess of information, or delaying of the introduction utterances; (2) the use of cohesive devices was concentrated in a particular expression. Suggestions based on the findings of the study are provided.

침지식 분리막 모듈에서 공기강도에 따른 분리막 위치에 대한 오염을 조사하였다. 분리막의 충진밀도가 낮은 곳에서 높은 유체 유속을 나타내었으며, 유체 속도는 기-액 주입률에 비례하였다. 전단응력은 기-액 주입률 및 유체 유속에 비례하였다. 비가역오염(Rir)은 흡입 압력이 가까운 부분에서 가장 높게 나타났다(position 1). 비가역오염에 대한 저항과 분리막 고유 저항의 비(Rir/Rm) 및 비가역오염에 대한 저항과 가역오염의 저항의 비(Rir/Rr)도 position 1에서 가장 높게 조사되었다. 비가역오염(Rir)은 흡입 압력이 높은 곳인 position 1에 오염물질이 축적되어진 결과이다. 분리막 위치에 따른 오염현상은 모듈 디자인 최적화에 중요한 인자임을 알았다.

분리막 생물반응조내 침지형 평막(공칭공경 0.15 ㎛, CPVC)을 사용하여 운전방식에 따른 막 오염 저감효과를 알아보았다. 또한 SMP, EPS와 같은 입자성 물질을 플록으로 형성시켜 장기운전을 가능하게 하였다. 운전방식은 기존 운전/휴지 방식과 연속적으로 처리수를 생산할 수 있도록 자체 개발한 사인파형 투과유속 연속운전(Sinusoidal flux continuous operation; SFCO)을 적용하였다. 응집제를 투여한 경우 기존 운전/휴지방식에 비하여 SFCO의 TMP는 최대 30% 미만으로 유지됨을 확인할 수 있었다.

Polytetrafluoroethylene (PTFE) membrane has high resistance to chlorine, which is a great advantages in chemical cleaning to recover water flux during membrane processes in drinking water systems. A humic kaolin water with approximately 4 mg/L of DOC and 10 NTU of turbidity was prepared as a feed water. Coagulation pretreatment with or without settling was applied. The coagulation with settling showed the greatest water production. The reduced flux was effectively recovered by NaOCl cleaning, i.e., 21% recovery by 50 mg/L of NaOCl cleaning and 49% recovery by 500 mg/L NaOCl cleaning. The images of SEM and AFM analyses were corresponded to the water flux variation. However, when the floc was accumulated on the membrane surfaces, the efficiency of NaOCl cleaning was substantially limited. In addition, dynamic contact angle became greater after cleaning, which indicates changes in characteristics of fouling layer such as surface hydrophobicity. Proper cleaning technologies during enhanced backwash using NaOCl would expand application of PTFE membranes in drinking water systems.

The determining the appropriate dosage of coagulant is very important, because dosage of coagulant in the coagulation process for wastewater affects removing the amount of pollutants, cost, and producing sludge amount. Accordingly, in this study, in order to determine the optimal PAC dosage in the coagulation process, CCD (Central composite design) was used to proceed experimental design, and the quadratic regression models were constructed between independent variables (pH, influent turbidity, PAC dosage) and each response variable (Total coliform, E.coli, PSD (Particle size distribution) (‹10 μm), TP, PO4-P, and CODcr) by the RSM (Response surface methodology). Also, Considering the various response variables, the optimum PAC dosage and range were derived. As a result, in order to maximize the removal rate of total coliform and E.coli, the values of independent variables are the pH 6-7, the influent turbidity 100-200 NTU, and the PAC dosage 0.07-0.09 ml/L. For maximizing the removal rate of TP, PO4-P, CODcr, and PSD(‹10 μm), it is required for the pH 9, the influent turbidity 200-250 NTU, and the PAC dosage 0.05-0.065 ml/L. In the case of multiple independent variables, when the desirable removal rate for total coliform, E.coli, TP, and PO4-P is 90-100 % and that for CODcr and PSD(‹10 μm) is 50-100 %, the required PAC dosage is 0.05-0.07 ml/L in the pH 9 and influent turbidity 200-250 NTU. Thus, if the influent turbidity is high, adjusting pH is more effective way in terms of cost since a small amount of PAC dosage is required.

본 연구는 오늘날 직장인에게 요구되는 다양한 역할에 있어 상사부하교환관계와 조직지원인식이 조직 의 행동에 어떠한 영향을 미치는가를 알아보았다. 무엇보다 조직유효성을 높이는데 있어 중요하게 인식 되고 있는 구성원의 조직응집력이 어떠한 영향을 미치며 또한 이들 간의 관계에 있어 일과 가정 사이에서 양립할 수 없는 개인의 역할 요구에 있어 느끼게 되는 갈등이 어떠한 역할을 하는지 알아보았다. 이를 위해 조직지원인식과 상사부하교환관계를 선행변수로 선정하였으며, 조직응집력 변수를 종속변수, 그리 고 일-가정 갈등과 가정-일 갈등을 조절변수로 선정하였다. 분석결과, 첫째, 조직지원인식과 상사부하교환관계 모두 조직응집력에 정의 유의한 영향을 미치는 것 으로 나타나 조직응집력을 높이는 것으로 나타났다. 둘째, 조절변수인 일과 가정 사이에서의 개인의 역할 갈등 중 일-가정 갈등은 조직응집력에 유의하지 않았으나, 가정-일 갈등은 유의한 부(-)의 영향을 미치는 것으로 나타나 가정-일 갈등이 조직응집력에 중요한 영향 요인임을 확인하였다. 마지막으로 일-가정 갈 등과 가정-일 갈등의 상호작용항을 투입한 조절효과의 경우 조직지원인식과 일-가정 갈등의 상호작용항 을 투입한 분석만 유의한 부(-)의 조절효과를 보이고 있다. 본 연구의 결과 조직지원인식과 상사부하교환관계가 구성원의 긍정적 태도를 강화하는 영향을 미친다 는 관계를 제시하고 있으며, 개인의 역할 갈등이 조직응집력에 부정적 영향 요인이라는 점에서 의의가 있음을 제시하였다. 하지만 일-가정 갈등과 가정-일 갈등의 조절효과 분석을 통해 오직 조직지원인식과 일-가정 갈등의 상호작용항만이 부(-)의 조절효과가 나타나 조직응집력에 있어 일에서 시작되는 역할 갈 등이 높을수록 조직응집력을 낮게 하는 효과가 있음을 제시하고 있다.

본 연구에서는 MBR 내에 침지된 분리막 오염을 평가하기 위하여 운전시간에 따른 막간차압(TMP)을 측정하였 다. 유효 막면적이 0.02 m2이고 공칭 세공크기가 0.15 μm인 정밀여과용 평막 모듈을 MLSS 5,000 mg/L인 활성슬러지 용액 에 침지시켰다. 운전/휴직(R/S) 및 사인파형 투과유속 연속운전(SFCO) 방식에 따른 TMP를 비교하기 위하여 동시에 투과 실 험을 수행하였다. SFCO 운전방법에 따른 TMP는 R/S에 비하여 최대 93% 낮게 유지되었으며 투과유속이 증가함에 따라서 TMP 감소 효과는 줄어들었다. 또한 응집제인 FeCl3를 활성슬러지 용액에 500 mg/L 농도로 주입시키면 SCFO 운전방식의 경우, 투과 운전시간을 5배 이상 증가시켜도 한계 운전 TMP인 55 kPa의 40% 미만으로 유지됨을 확인할 수 있었다.

This study examined a feasibility of coagulation as post-treatment to remove sulfide and phosphorus for the effluent of anaerobic fluidized bed reactor (AFBR) treating domestic wastewater. Removal efficiencies of sulfide, phosphorus and COD by coagulation were not affected by pH in the range of 5.9 to 7.2. Alkalinity requirement could be estimated by the amount of Fe3+ to form Fe(OH)3(S) and to remove sulfide and phosphorus. At coagulant aid dosage of 2 mg/L, anionic polymer showed best results regarding size and settleability of flocs. Sulfide removal for the AFBR effluent at the Fe3+/S2- ratio of 0.64, close to the theoretical value of 0.67 found with a synthetic wastewater, was only 75.2%. One of the reasons for this low sulfide removal is that the AFBR effluent contains, phosphorus, hydroxide and bicarbonate which can react with Fe3+ competitively. Concentrations of sulfide and phosphorous reduced to below 0.1 and 0.5 mg/L, respectively, at the Fe3+/S2- ratio of 2.0. Average effluent COD of 80 mg/L, mostly soluble COD, was obtained at the dosage 50 mg Fe3+/L (Fe3+/S2- ratio of 2.0) with corresponding COD removal of 55%. For better removal of COD, soluble COD removal at the AFBR should be enhanced. Coagulation with Fe3+ removed sulfide, phosphorus and COD simultaneously in the AFBR effluent, and thus could be an alternative process for the conventional wastewater treatment processes where relatively high quality effluent is not required.

본 연구에서는 직장인의 음주행위와 조직응집력 간의 관계에 있어 음주동기의 조절효과를 살펴보기 위하여 음주행위는 독립변수, 조직응집력은 종속변수로 설정하였으며, 그리고 조절변수로는 음주동기의 하위변인인 고양동기, 대처동기, 동조동기, 그리고 사교동기를 선정하였다. 연구의 결과, 음주행위가 조직응집력에는 유의한 영향을 미치지 않는 것으로 나타났으나, 조직응집력에 대한 음주동기는 부분적으로 유의한 영향을 미치는 것으로 나타났다. 먼저, 고양동기와 사교동기의 경우 유의한 정(+)의 영향을 미치는 것으로 나타났으며, 대처동기는 유의한 부(-)의 영향을 미치는 것으로 나타났다. 반면, 동조동기는 유의한 영향을 미치지 못하는 것으로 나타났다. 마지막으로 음주행위와 조직 응집력 간의 관계에 있어 음주동기의 조절효과를 검증한 결과 음주동기의 사교동기만이 유의한 정(+)의 조절효과를 보이는 것으로 나타났으며, 고양동기, 대처동기, 그리고 동조동기는 조절효과가 없는 것으로 나타났다. 이상의 결과로 보아 음주가 조직응집력에 유의한 영향을 미치지 못하여 조직에 긍정적 영향을 미치지 못할 것으로 보았으나, 음주행위와 사교동기의 상호작용 효과를 통해 나타난 바와 같이 음주동기의 차이에 따라 조직 내 구성원의 태도에 다르게 영향을 미침을 시사하고 있다. 즉, 구성원 간의 상호작용을 위한 목적의 수단으로써 음주를 하게 된다면 음주가 긍정적 역할을 하는 것은 물론 조직 구성원 간의 응집력을 높이는 데 있어 유용한 도구로 사용될 수 있을 것으로 판단된다.

본 연구에서는 정제되지 않은 ZnO 및 TiO₂나노입자를 M4배지에 노출시켜 두 나노입자가 어느 정도 크기의 응집체로 변화되는지를 살펴보고 또한 두 나노입자가 수생태계 생물종인 Daphnia magna에 어떠한 영향을 초래하는지 유영저해 및 폐사율을 통해 살펴보았다. ZnO 및 TiO₂나노입자의 분말상태 크기는 각각 20 nm와 40 nm였지만, M4배지에서는 1333 nm와 1628 nm로 약 40~70배의 크기로 응집되었다. 유영저해의 경우 ZnO와 TiO₂나노입자 모두 시간 및 농도가 높아질수록 D.magna가 유영하는데 영향을 미친 것으로 나타났으며, 특히 ZnO나노입자가 TiO₂나노입자에 비해 더 큰 영향을 미치는 것으로 나타났다. 폐사율의 경우 ZnO나노입자에서는 시간 및 농도가 높아질수록 폐사되는 비율이 높았으며, TiO₂나노입자에서는 72시간이 경과된 시점의 10 ppm 이상의 농도에서 폐사하는 것으로 관찰되었다. 이는 나노입자가 해양에 유입됨으로 인해 원래의 크기에 비해 응집되어 증가되어진다는 것을 알 수 있으며, 또한 그 응집체로 인해 수생태계 생물에 영향을 주는 것으로 나타났다.

A coagulation-flocculation (CF) process using aluminum sulfate as a coagulant was employed to treat highly suspended solids in tunnel wastewater. Response surface methodology (RSM) based on a Box-Behnken design was applied to evaluate the effects of three factors (coagulant dosage, pH and temperature) on total suspended solids (TSS) removal efficiency as well as to identify optimal values of those factors to maximize removal of TSS. Optimal conditions of coagulant dosage and pH for maximum TSS removal changed depending on the temperature (4 ~ 24°C). As temperature increased, the amount of coagulant dosage and pH level decreased for maximum TSS removal efficiency during the CF process. Proper adjustment of optimal pH and coagulant dosage to accommodate temperature fluctuations can improve TSS removal performance of the CF process.