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인분 퇴비화에 대한 첨가제의 역할
Get PDF학위논문 (석사) -- 서울대학교 대학원 : 공과대학 건설환경공학부, 2020. 8. Mooyoung Han .이 연구는 인분에 있어 분변 분리형 건식 화장실(UDDT)로부터의 소규모 현지 인분 처리를 위한 퇴비화 조건 향상에 대한 첨가제의 역할을 보여준다. 첨가제는 질소 손실을 줄이고 유기물질의 분해를 줄이면서, 병원균 제거 효율에 있어 중요한 역할을 한다. 첨가제의 성분과 사용하는 양에 따라 효과는 다르다. 그러한 목적으로 재와 볏짚의 2가지 첨가제가 선정이 되었고, 이들은 현지 지역, 특히 시골 및 농경지에서 쉽게 구할 수 있다. 모든 실험은 실험실 규모로 진행이 되었다.
변과 재는 퇴비화 과정 및 생성물에 보다 나은 효과를 줄 수 있는 최적의 양을 선정하기 위하여 3가지 비율(1:1, 1:3, 1:5)로 혼합이 되었다. pH, 유기물질 함량 또는 총 유기탄소 함량이 주로 측정이 되었으며, E.Coli 농도 변화가 실험 과정에서 측정이 되었다. 최대 pH 11.28이 1:3 비율 조건에서 얻어졌으며, 이 조건에서 유기물질의 감소율은 매우 낮았다. 1:1(v/v) 조건은 pH 10.8의 결과값을 보였으며, pH>10을 멸균 조건에서 실험 기간 이후에도 계속적으로 유지하였다. E.Coli 농도는 WHO기준(2006)을 만족하며 가장 높은 분해율을 보였다. 그래서 1:1 비율이 재를 이용한 전체 변 처리에서 가장 효과적인 것으로 보인다.
유기물질의 안정화를 위하여, 각각 다른 비율(1:0.5, 1:1, 1:2)의 변과 볏짚 혼합물이 조사되었다. 3가지 비율의 변과 볏짚 중, 1:2(v/v) 비율에서 총유기탄소 비율을 51%에서 22%으로 줄였으며, 유기물질 분해에 더 나은 결과를 보였다. 이 조건은 또한 용해성 총 질소의 회수율이 가장 높았으며 E.Coli 제거율이 가장 높았다. 이 조건은 70일 이후에 숙성된 퇴비화 작업이 마쳐졌다. 하지만, 병원균 농도를 안정적으로 맞추는데 있어서는 84일이 소요되었다. 그럼에도 불구하고, 1:2 비율이 볏짚을 이용한 변의 전반적인 처리에 가장 효과적인 것을 확인하였다.
짧은 시간 내에 병원균이 없는 숙성된 퇴비를 얻기 위해서, 2개의 첨가제가 다음의 최적 비율로 변과 혼합이 되었다: F:Ash:RS (1:1:2). 볏짚과 재를 섞은 결과는 하나의 첨가제만을 사용한 것과 비교하였을 때 더 나은 결과를 보였다. 이것은 볏짚을 이용한 유기물질의 안정화와 재를 이용한 병원균 저감이 동시에 일어났기 때문으로 사료된다. 그러므로 건식 화장실에 있어서 1:1:2 비율의 변, 재, 볏짚의 비율이 병원균이 없는 숙성된 퇴비를 만드는데 가장 최적이다.This research present the effect of additives on human feces with different ratios to improve the composting conditions of small-scale on-site feces treatment for urine dividing dry toilet (UDDT). Additives play as an important role for pathogen removal efficiency, reducing nitrogen loss and decomposition of organic matter. Depending on the characteristics of the additives and using amount, the effects are different. For those purposes, two additives; ash and rice straw were selected which are readily available in the local areas, especially in rural and agricultural sites. All the experiments were performed in laboratory scales.
Feces and ash were mixed into three ratios (1:1, 1:3, 1:5) to estimate the optimal amount to have better effects on composting process and end-products. pH, organic matter content or total organic carbon content and mainly, Escherichia coli (E.coli) concentration changes were measured during the process. Highest pH 11.28 was obtain from (1:3) ratio while it had very lower reduction rate of organic matter .1:1 (v/v) achieved pH 10.8 and it maintained pH >10, a sanitization level, even after the experiment period. The E.coli concentration level to meet the guideline of WHO (2006) while maintaining the highest decomposition rate. Thus 1:1 presented the most effective for overall feces treatment with ash.
For stabilization the organic matter, different ratios with feces and rice straw (1:0.5, 1:1, 1:2) were also investigate Among three ratio Feces and rice straw, ratio 1:2 (v/v) reduced the TOC content from 51% to 22%. Which shown the better results for decomposition of organic matter. It also had high recovering soluble TN and reducing E.coli content. It achieve the mature compost after 70 days. However, it took 84 days to reach the safety level of pathogens concentration. Thus, 1:2 presented the most effective for overall feces treatment with rice straw.
To obtain pathogen free mature compost during a short time, 2 additives were mixed together with feces by following the optimal ratios F:Ash:RS (1:1:2). Combine mixing of rice straw and ash showed the better results compare to one additive. That was due to organic matter stabilization by rice straw and pathogen reduction by the present of ash happened at the same time. Thus, 1:1: 2 ratio of Feces, ash, rice straw is a good portion for composting of human feces in dry toilet to achieve pathogen free mature compost.Chapter 1: Introduction 1
1.1 Background 1
1.1.1 Current global sanitation 1
1.1.2 Urine-diverting dry toilet (UDDT) 5
1.1.3 Human feces 7
1.1.4 Role of additives in composting human feces 8
1.2 Objectives 10
1.3 Dissertation structure 11
References 13
Chapter 2: Choosing Additives and Composting Experiment 17
2.1 Choosing additives 17
2.2 Materials and Methods 18
2.2.1 Materials preparation 18
2.2.1 Composting experiment design 19
2.2.2 Measurement of physio-chemical properties 21
2.2.3 E.coli analysis 23
Reference 24
Chapter 3: Investigation and optimization of mixing ratios of human feces and ash 27
3.1 Results and discussion 27
3.1.1 pH 27
3.1.2 E.coli die off 28
3.1.3 Total organic matter reduction 29
3.2 Summary 30
Reference 32
WHO. 2006. "Guidelines for the Safe Use of Wastewater, Excreta and Greywater." Excreta and Greywater Use in Agriculture no. 4 (ISBN: 92 4 154685 9). 34
Chapter 4: Investigation and optimization of mixing ratios of human feces and rice straw 35
4.1 Results and discussion 35
4.1.1 pH 35
4.1.2 Changes in NH4+/NO3- 36
4.1.3 Changes in Soluble TN 37
4.1.4 E.coli die off 38
4.1.5 Total organic matter reduction 39
4.2 Summary 40
Reference 41
Chapter 5: Reducing human feces treatment time by adding combine additives 43
5.1 Introduction 43
5.2. Composting experiment design and Physio-chemical analysis. 44
5.3 Result and discussion 44
5.3.1 pH 44
5.3.2 Changes in NH4+/NO3- 45
5.3.3 Changes in Soluble TN 46
5.3.4 E.coli die off 47
5.3.5 Total organic matter reduction 48
5.4 Summary 49
Reference 50
Chapter 6: Conclusion and Recommendation 52
6.1 Summary 52
6.2 Recommendation 53
Acknowledgement 57Maste
FN을 이용한 케이크 여과의 수학적 모델링과 실험적 검증
Get PDF학위논문 (박사)-- 서울대학교 대학원 : 건설환경공학부, 2015. 2. Mooyoung Han.최근에 탈수공법은 고체-액체 분리가 중요한 역할을 하는 입자분리, 하수 슬러지 처리, 제약 산업, 양조장과 음식 폐기물 관리 등 여러 분야에서 많은 관심을 이끌었다. 슬러지 탈수 공법 중에도 케이크 여과는 광범하게 사용되고 있다.
케이크 여과에는 양 압력이 적용되어 슬러지 내의 수분이 제거된다. 수분 제거는 슬러지와 필터에 의해 저항으로 한다. 현재까지 케이크 여과의 거동모형은 케이크 저항이나 필터 차단으로 개발되었다. 본 논문은 1-차원 케이크 여과 과정의 여과 거동과 단계를 평가하는 해석적 모형을 제시하였다. 제시된 모형은 에너지법칙을 이용하여 여과 매체의 저항 영향을 고려하고 새로운 매개 변수인 필터계수 (FN)가 적용된다. 하수 슬러지에 대해 여과 실험으로 제시된 모형을 검토했다. 실험 과 모형을 비교한 결과, 압력 300 kPa에는 평균상대오차가 21%이고 500 kPa에는 평균상대오차가 31%이다. 결론으로 본 논문에서 제시된 모형은 여과시간과 케이크 여과 과정의 단계를 예측할 수 있다.
압력 및 시간은 실제 운영에는 에너지 및 비용과 밀접한 관계가 있다. 슬러지의 종류와 상태에 따라 어떤 경우에는 압력이 제한 조건으로 되고 어떤 경우에는 시간이 제한 조건으로 된다. 요구되는 탈수 정도와 제한 조건을 고려해서 탈수 운영 그래프를 플롯팅할 수 있다. 그래프 플롯팅은 예측 모형에 의해 이뤄졌고 이 그래프를 통하여 가장 경제적 방법을 선택할 수 있다.Recently, dewatering has received great attention in many fields, includingparticle separation, wastewater sludge treatment, pharmaceutical industries, wineries and food waste management in which solid and liquid separation is important. Among the several types of sludge dewatering techniques, the most widely used is cake filtration. In cake filtration a positive pressure is applied to force liquid through the cake and filter medium. The cake filtration can be divided into two phasesfiltration phase and expression phase. In filtration phase liquid pass through the cake and filter medium while a free suspension is still left on top of the cake. However the expression phase focuses in the removal of the water by squeezing the cake. In expression phase the sludge and filter resistances are stabilized. For decades, the performance of cake filtration has been modeled based on the cake resistance and/or filter blockage. However further study and development of less complicated model is required to appropriately assess the relationship between the cake and the filter resistance, especially filter clogging, as well as the conditions of both the filtration and expression phases.
In this study, a new model for evaluating the filtration and expression phases of a one-dimensional cake filtration process is proposed. The effect of the filtering medium resistance was considered applying energy law and using a new concept of filter number (FN). The effects of the governing parameters on the model predications for both the filtration and expression phases were also investigated. Based on sensitivity analysis of the model on the governing parameters, during the filtration phase the effect of the cake hydraulic conductivity was found to be negligible whereas the compacted sludge layer and filter medium plays the primary role. On the other hand, the hydraulic conductivity of the filtration cake is the dominant factor during the expression phase. Moreover the findings of the model sensitivity analysis are also used to make some cake filtration suggestions.
Four filtration experiments with two types of filter at two pressures (300 kPa and 500 kPa) were performed for wastewater sludge from Gawchon wastewater plant and repeated (totally 8 tests). The Experimental data obtained in this study were used to verify the proposed model. The experimental data and model prediction were compared and regression analysis was made to find the agreement and disagreements part of the model with data. Based on observations form laboratory tests, we found that the new model provides a mean relative error (MRE) of 21%, 31%, 28% and 29% between predicted and observed values of the filter types I and II at 300 and 500 kPa respectively.
The model can be used to predict the time for achieving the certain percent of sludge dewatering which can be very useful in many industrial applications. Pressure and time in the real operational field means energy and money. In some cases, pressure is the limiting factor and sometimes time is the limiting factor, depending on the type of sludge and condition. Based on the demand to achieve the certain degree of dewatering and also by considering the limiting factors of the company, it is possible to plot dewatering operational graph based on model prediction into the most economical way that the company can have.Abstract………………………………………….................. i
Table of content………………………………………….... iv
List of figures……………………………………………... ix
List of tables………………………………………………. xiii
Nomenclature …………………………………………….. xiv
CHAPTER 1………………………………………………. 1
Introduction………………………………………………. 1
1.2. Background…………………………………… 1
1.3. Research Objectives………………………………………….. 6
1.4. Dissertation organization…………………….. 7
CHAPTER 2………………………………………………. 9
Literature Review………………………………………… 9
2.1. Introduction……………………………………………… 9
2.2. Conventional model………………………………… 10
2.3. Diffusional model……………………………………... 14
2.4. Multi-phase (3D)……………………………………… 16
2.5. Particle Dynamic Approach………………………….. 17
2.6. Consideration Theory………………………………. 19
2.7. Conclusion……………………………………………….. 22
CHAPTER 3………………………………………………. 24
Cake filtration modeling…………………………………. 24
3.1. Introduction……………………………………………… 24
3.2. Energy balance equation………………………………………… 26
3.2.1. Model Theory ………………………………..….. 26
3.2.2. Head loss through cake…………………………….. 28
3.2.2.1. Determination of hydraulic conductivity…………. 31
3.2.2.2. Sample calculation of hydraulic conductivity…... 33
3.2.3. Head loss through filter medium…………………….. 37
3.2.3. Basic equations…………………………………….. 38
3.3. Filter number…………………………………………….. 40
3.3.1. Definition of filter number…………………………... 40
3.3.2. Sample calculation of filter number ……………. 43
3.4. Governing equations……………………………... 47
3.4.1. Filtration phase…………………………………. 47
3.4.2. Expression phase……………………………. 48
3.5. Model sensitivity………………………………………… 50
3.5.1. Filtration Test …..…………………………………… 50
3.5.1.1. Wastewater sludge…………..…………………….. 50
3.5.1.2. Experimental set-up and procedure ………… 51
3.5.1.3. Initial and experimental parameters ………..….. 52
3.5.2. Effect of governing parameters……………………… 55
3.5.2.1. Effect of pressure head……………………………. 56
3.5.2.2. Effect of hydraulic conductivity…………...……... 57
3.5.2.3. Effect of filter number………..………………….... 59
3.8. Discussion……………………………………………... 60
3.9. Conclusion……………………………..……………….... 62
CHAPTER 4……………………………………………… 64
Model Evaluation…………………………………...…….. 64
4.1. Introduction……………….…………………………... 64
4.2. Laboratory Experiment……..…………………………… 65
4.2.1. Materials and preparation………………………........ 65
4.2.1.1. Wastewater sludge…………………………….. 65
4.2.1.2. Filters…………………………………………... 67
4.2.1.3. Experimental set-up……………………………. 68
4.2.2. Filtration experiment condition and procedure……. 69
4.2.3. Experiment results………………………………... 70
4.3. Model prediction………………………………………… 71
4.3.1. Pre-experiments…………………………...…………. 71
4.2.1.1. Filter number for clean filter (FN0)……….....… 71
4.3.1.2. Hydraulic Conductivity of Cake………………. 73
4.3.2. Filter number function, FN(t)…………………...… 75
4.3.3. Results of model prediction…......…….………….. 76
4.4. Comparing experimental and modeling results…… 78
4.4.1. Model verification……………….…………………….. 78
4.4.1.1. Error analysis………….……………………….. 80
4.4.1.1.1. Regression Analysis…………….….. 80
4.4.1.1.2. Mean Relative Error……….……….. 82
4.5. Conclusion……………...………….……………………. 82
CHAPTER 5……………………………………………… 84
Model Application………………………………………... 84
5.1. Introduction……………….…………………………… 84
5.2. Degree of dewatering, %D……..………………………. 86
5.3. Operational Diagram………………………………….... 89
5.4. Discussion and Conclusion…...………………………. 90
CHAPTER 6………………………………………………. 91
Conclusion………………………………………………… 91
Appendix………………………………………………….. 93
References…………………………………………………. 96Docto
IoT를 활용한 가정 용수 절약 및 지속가능전략제안
Get PDF학위논문 (석사)-- 서울대학교 대학원 : 공과대학 건설환경공학부, 2018. 8. Mooyoung Han.Much of the water conservation effort has focused on the technological advancement of water-using appliances to make them more water efficient. How-ever, since user interaction with water-using appliances is a major influence on the amount of water used by the appliance, which is itself influenced by the habits, rituals, and expectations of water use, more research is needed that focuses on the user. In this research, IoT application is illustrated through a real implementation of one household water consumption monitoring system. A novel wireless water consumption monitoring system is designed, in which flow rate sensors are placed at different detection spots in a house to collect data, there are two main catego-ries of water saving measures to reduce water use: technical measures include network improvement, repair leaks, developing water-efficient appliancesnon-technical measures cover information, education, awareness that may change con-sumptive habits. This research focuses on both of them and presents the ways of intervening peoples water consumption behavior by using the Internet of Things (IoT) technologiesThis thesis explores a new approach for disaggregating of the end use of residential water consumption by using new technology for real-time monitoring and develop sustainable strategies. The first stage of the study was developing IoT flow meter sensor and installed it in the selected representative household for five months in Ajlune cities, Jordan, for monitoring water consumption in each part of the home. The second stage undertook household survey about the amount of water they used in each part, daily routine, and the highest part of consuming water. The third stage is to suggest some sustainable strategies.
The main goal of this research is to decrease water use consumption by improving family members awareness by using IoT flow meter sensors and sug-gest some sustainable strategies.The result shows that thebehaviors of family members were changed and LPCD at this house was: 126 Liter, but reduced to 109 Liter after monitoring.List of tables I
List of Figures II
CHAPTER 1 INTRODUCTION 1
1.1 Research background 1
1.2 Research objects and scope 5
1.3 Research method outline 6
1.4 Assumption and limitation 7
CHAPTER 2 LITERATURE REVIEW 9
2.1 The water condition in Jordan 10
2.2 Water supply system in Jordan 15
2.3 IoT Technology in water management 16
2.4 IoT flow meter sensor 17
CHAPTER 3 RESEARCH METHOD AND DESIGN 21
3.1 Overview of research method and design 21
3.2 Water conservation using IoT 22
3.2.1 Site description 22
3.2.2 Home information 23
3.2.3 IoT design of the application 25
3.2.4 Install flow meters inside and outside home 28
3.2.5 Survey 30
3.2.6 Seasonal dynamics of water uses 30
3.3 Potential strategies 31
3.3.1 Options for saving-water equipment's 36
3.3.2 Strategies evaluation 37
CHAPTER 4 RESULT 39
4.1 Daily water consumption 39
4.2 Comparison of water consumption 40
4.3 Behavior of water consumption 41
4.4 Water consumption at each unit 43
4.5 Survey result 46
4.6 Water saved effectiveness 49
4.7 Cost evaluation for conservation strategies 48
CHAPTER 5 Conclusion and contribution and implication 56
5.1 Research objective and outcome 56
5.2 Study contribution 57
5.3 Study limitation and future research directions 59
APPENDIX
REFERENCEMaste
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
양(+)의 나노기포 생성과 색도 제거 및 기름-모래 분리에서의 적용
Get PDF학위논문(박사)--서울대학교 대학원 :공과대학 건설환경공학부,2020. 2. Mooyoung Han.나노버블 기술은 이론적으로 그리고 실험적으로 화학물질 소비가 적고 처리시설의 규모를 줄일 수 있는 경향이 있다고 알려져 있다. 따라서 설계 및 작동 비용 절감으로 인한 친환경적 기술로의 상당한 가능성을 가지고 있다. 이러한 관점에서 다양한 조건 하에서 수처리 및 물질 분리 공정을 위한 NB 기술이 연구되어 오고 있으며, 대부분의 경우 NB 표면 전하는 처리 효율에 연관된 주요 인자 중 하나이다. 따라서 이 연구는 양의 전하의 NB를 3가 금속이온(특히Al3) 존재 하에서 발생시키고 이러한 NB를 색도 제거 및 기름-토양 분리에 적용하는 것에 집중하고 있다. 이 연구에서 NB는 믹싱챔버에서 과포화된 공기-물 혼합체가 퍼지면서 생성이 된다. 이는 그 후 테프론 호스에서 미세기포의 분해를 일으킨다. NB의 사이즈와 제타 전위는 동적광산란에 의해 측정이 되었다. 전반적으로 NB의 사이즈는 pH에 의한 경향이 없고 시간에 따라 커지며 여기서 사이즈 증가의 가능한 매커니즘은 용액 내에서의 응집과 연관이 되어있다.
양의 전하를 가진 NB는 화학적 시약의 존재 하에 관찰이 되며 특히Al3+ 는 수처리에서 가장 널리 사용되는 응집제이다. 양의 NB 생성은 양이온의 계면활성제(dimethyldioctadecylammonium bromide)의 존재 하에 확정이 되며, 3가 금속 이온의 추가로 만들어진다 (Al3+ and Fe3+).
NB의 제타전위는 pH 2에서 12까지 증가하면서 모든 용액에서 감소한다. Al3+ 의 존재 하의 양의 NB는 특정 양이온 물질(pH<6 에서) 및 NB 표면의 수화물 침전(pH=6-9에서)에 의해 생성이 된다. Al3+ 의 양의 제타 전위 거동에의 영향이 아래의 조건에서 관찰이 되었다: [Al3+] 0에서 10mM 농도로 150분. 결과는 [Al3+]는 NB의 사이즈에 거의 영향을 주지 않으며 NB의 제타전위는 0, 0.5, ≥ 1 mM 일때 각각 음으로 하전, 전하를 띠지 않고, 양으로 하전되었다. 최대의 제타 전위는 ≥ 2 mM Al3+의 농도를 넣어주었을 때 +20 ± 2 mM였다. 모든 경우에 제타 전위는 150분 이후에는 유지가 되었으며 제타 전위 분석으로 NB의 안정성에 대한[Al3+]의 현저하지 않은 영향에 대해 확인할 수 있었다. 이러한 관점에서[Al3+]의 존재하의 양의 NB는 색도 제거 및 기름-모래 분리를 위한 처리 효율을 평가하는데 사용이 되었다.
색도 제거에 대한 실험적인 결과는 Al3+만을 사용했을 때와 H2O2 만을 사용했을 때를 비교하기 위한 진초록색의 Rit 염색약의 색도 제거로 확인을 하였다. 그리고 양의 NB의 역할, NB만을, 초음파 NB, NB/H2O2를 사용했을 때 공정에서 색도제거 비율에 대한 반응성에 대해 확인하였다. Al3+만을 사용했을 때와 H2O2 만을 사용했을 때 색도 제거 과정은 Rit dye가 500~1200 CU의 농도로 포함이 되어있는 칼럼 반응조의 바닥에 30%의 버블 비율로 기포 용액을 주입하여 자테스트를 하는 것으로 진행이 되었다.
모든 경우에 약한 색깔을 띨수록 색도 제거가 잘 되는 것을 보였다. 게다가 NB 시스템을 이용한 색도 제거가 기존의 방식을 사용하는 것 보다 효과적이었다. 두 염료 농도에서 양의 초음파 NB (제타 전위 +15mV에서 +20mV)와 양의 NB/H2O2 (1 mM) 시스템이 효과적인 처리 과정으로 판단이 되었다. 색도 제거의 매커니즘은 양의 NB와 염료 성분의 정전기식 인력 때문이다.
게다가 OH∙, HO2∙, 그리고 O2∙ 의 반응기들은 초음파 NB와 NB/H2O2 시스템에서 Rit 염료의 저감능력 향상에 있어서 기본적이다. 90% 이상의 Rit 염료가 30분 이내에 제거가 되었으며, 초음파 NB와 NB/H2O2 계에서는 60분 후에 제거가 되었다. 다양한 NB의 존재하에 다른 색도 제거 시간이 기체상에서 응집물질 상으로 변환이 되는 것에 기여를 하였으며 반응기와 Rit 염료 성분의 반응 역학에 영향을 끼쳤다.
기름-모래 분리에의 적용에서 NB의 주입은 TPH 제거율 85% 이상으로 효과적인 처리 공정임이 밝혀졌다. 결과는 NB/기름-모래 비율, 분리 시간, NB주입(배치, 간헐적 반응)이 NB 공정으로 기름-모래 분리의 효율에 영향을 끼치는 것으로 드러났다. 초음파의 적용은 분리능력을 현저하게 향상시키지는 않는 것으로 드러났다. 결과적으로 2/1(v/v) 비율의 NB/기름-모래에서 양의 NB(제타전위 +15에서 +20mV)의 간헐적 주입이 높은 TPH 제거율을 얻을 수 있었다.
그러나, 음으로 하전된 NB 기술은 또한 높은 NB/기름-모래 비율과 긴 처리시간을 요구하지만 기름-모래 분리를 할만한 기술인 것으로 고려가 되었다. 부력이 기름을 떨어뜨리는데 주요한 역할을 하였다. 기포와 기름 층 사이의 큰 외부 접촉각이 기름-모래 반응조에서 NB의 응집으로 인한 미세기포와 매크로기포의 생성을 한다고 밝혀졌다. 그리고 기름층에 부착이 된 응결된 기포의 수의 증가는 더 나은 TPH의 제거를 위해 더 강한 부력을 생성하기에 필수적이라는 것을 알 수 있었다.
NB 공정은 오염된 물의 색도 제거와 기름-모래 제거를 위한 믿을만한 증거가 될 것이라는 것을 확인이 되었다. 두 분야 모두에서 NB의 제타전위 +20mV 값에서 최적의 처리 효율을 보인다는 결과를 얻을 수 있었다. Al3+의 추가로 형성이 된 양의 NB를 사용하는 기술이 가장 효과적이라는 사실이 밝혀졌다. 이 연구에서의 발견은 수처리와 토양 완화를 위한 새로운 지평으로써 NB 기술의 더 나아간 적용을 말해준다.Nanobubble (NB) technologies are theoretically and experimentally known to be less chemical consuming and considerable tendency of reducing size of the treatment facility. Hence, they have significant potential for design and operational cost reduction on top of their contribution as an environment friendly technique. With this respect, some feasible applications of the NB technology for water-treatment and particle separation processes are studied under various conditions and in most of the cases the NB surface charge is one of the major that affects the treatment efficacy. This study therefore focuses on on generation of positively charged nanobubble (NB) in the presence of tri-valent metal ions (especially Al3+) and the applications of such NB for color removal and oil-sand separation. In this research, the NB were produced by dispersing a supersaturated air-water mixture in a mixing chamber, and then causing the breakup of microbubbles in a Teflon hose. The size and zeta potential of the NB were measured by dynamic light scattering. Overall, the NB size had no dependency on pH and grew over time and here, the possible mechanism for the size growth was related to their coalescence in the solutions.
The generation of positively charged NB was observed in the presence of chemical reagents, especially Al3+ - the most widely-used coagulant in water treatment. Positive NB generation was confirmed in the presence of the cationic surfactant (dimethyldioctadecylammonium bromide) and was resulted in the addition of tri-valence metal ions (Al3+ and Fe3+). The NB zeta potential decreased in all solutions, while their pH increased from 2 to 12. The positively charged NB in the presence of Al3+ were created from the specific cationic species (at pH < 6) and hydroxide precipitates (at pH = 6 – 9) on the NB surface. The effects of Al3+ on the behavior of the positive ZP was then observed under conditions: [Al3+] from 0 to 10 mM and timeframe of 150 min. The results showed that [Al3+] had little effect on the NB size and the NB zeta potential was negatively charged, zero-charged, and positively charged in the addition of [Al3+] of 0, 0.5, and ≥ 1 mM, respectively. Maximum positivity of the ZP was obtained at ~ +20 ± 2 mM when adding ≥ 2 mM Al3+. At all cases, the zeta potential remained over 150 min, confirming the insignificant effects of [Al3+] on the NB stability via the ZP analysis. With these respects, the positive NB in the presence of Al3+ were then used to investigate the treatment efficiency for color removal and oil-sand separation.
The experimental results on decolorization proved color reduction of dark green Rit dye using NB in comparison with using Al3+ alone and H2O2 alone; and showed the role of positive NB, reactive species on decolorization ratio in the processes using NB alone, ultrasonic NB, and NB/H2O2. The color removal processes with Al3+ alone and H2O2 alone were performed using a jar tester while bubbling solutions were injected at a bubble rate of 30% through the bottom of a column reactor containing Rit dye at concentrations of ~500 and ~1200 CU. The results indicated greater color removal for weaker colors at all cases. Furthermore, the decolorization rate using NB systems was more efficient than that using conventional processes. In both dye concentrations, positive ultrasonic NB (ZPs of +15 mV to +20 mV) and positive NB/H2O2 (1 mM) systems were found to be effective treatment processes. The color removal mechanisms were owing to the electrostatic attraction between the positive NB and dye components; furthermore, reactive species such as OH∙, HO2∙, and O2∙ were fundamental in enhancing Rit dye degradation in ultrasonic NB and NB/H2O2 systems. More than 90% of Rit dye removal was obtained within 30 min and after 60 min in the ultrasonic NB and NB/H2O2 systems, respectively. Different decolorization times under various NB presences were attributed to the transfer from the bubbly regime to aggregate regime, and the reaction kinetics of the reactive species and Rit dye components.
In the application for the oil-sand separation, the injection of NB was shown to be an effective treatment process with TPH removal ≥ 85%. The results demonstrated that the NB/oil-sand ratio, separation time, and NB injection (i.e. batch and intermittent regimes) were found to noticeably affect the separation efficiency of the oil-sand by the NB process. The application of the ultrasonic sound was proved to insignificantly improve the separation performance. As resulted, greater TPH removal was obtained with the intermittent injection of positive NB (ZP from +15 to +20 mV) at NB/oil-sand of ≥ 2/1 (v/v), and the separation time from 5 to 20 min. However, negatively charged NB technology can be also considered as a reliable application for the oil-sand separation even it required the greater NB/ oil-sand (ca. ≥ 3/1) and longer treatment time (ca. 40 min). Buoyancy force played the major role on detaching the oil. It was found that the larger external contact angle between bubble and oil layer, the creation of microbubble and macrobubble via NB coalescence in the oil-sand reactor, and the increase in the number of coalesced bubble attached on the oil layer were fundamental to produce stronger buoyancy force for the better TPH removal.
The NB processes were confirmed to be a reliable evidence for the decolorization of polluted waters and the oil-sand separation. In both fields, the better treatment efficiency was obtained in accordance with the optimal NB zeta potential value of +20 mV; giving the fact that the technology using positive NB formed in the addition of Al3+ was the most effective. The findings from this study allow further applications of NB technology as a new horizon for water treatment and soil remediation.CHAPTER 1. INTRODUCTION 1
1.1. Background 1
1.2. Research Objectives 5
1.3. Dissertation structure 6
References 8
CHAPTER 2. LITERATURE REVIEWS 12
2.1. Overview on nanobubble (NB) 12
2.2. Physical properties of the NB 14
2.2.1. NB size 14
2.2.2. Zeta potential of NB 19
2.3. Bubble technology for decolorization and oil-sand separation 25
2.3.1. Decolorization 25
2.3.2. Oil removal 27
References 29
CHAPTER 3. GENERATION OF POSITIVELY CHARGED NANOBUBBLE 39
3.1. Introduction 39
3.2. Methodology 40
3.2.1. NB generation 40
3.2.2. Experimental setup 44
3.2.3. NB size and zeta potential measurement 44
3.3. Positively charged NB generation in different reagent solutions 46
3.3.1. Creation and average size of NB 46
3.3.2. Zeta potential of NB 52
3.4. Behavior of NB in the presence of various Al3+ concentration 58
3.5. Summary 62
References 64
CHAPTER 4. DECOLORIZATION OF RIT DYE USING POSITIVELY CHARGED NANOBUBBLE TECHNOLOGY 70
4.1. Objectives 70
4.2. Experimental 70
4.2.1. In coagulation and oxidation processes 70
4.2.2. In NB technologies 71
4.3. Bubble properties observation and hydroxyl radical determination 72
4.4. Color measurement and quality control 73
4.5. Results and discussion 74
4.5.1. Color removal efficiency 74
4.5.2. Optimization of charged NB processes 77
4.6. Summary 90
References 91
CHAPTER 5. SEPARATION OF OIL-SAND USING POSITIVELY CHARGED NANOBUBBLE TECHNOLOGY 95
5.1. Objectives 95
5.2. Experimental 95
5.2.1. Materials and reagents 95
5.2.2. Experimental setup 97
5.2.3. Method validation 100
5.3. Bubble coalescence in oil-sand reactor 101
5.4. TPH removal efficiency 107
5.4.1. In different separation processes 107
5.4.2. Optimization of NB technologies for oil-sand separation 112
5.4.3. Change of the oil-sand morphology using NB technologies 120
5.5. Summary 123
References 124
CHAPTER 6. CONCLUSIONS AND RECOMMENDATIONS 126
6.1. Conclusions 126
6.2. Recommendation for further study 128Docto
다목적 빗물관리를 위한 소규모의 수문학적 모델링
Get PDF학위논문 (박사)-- 서울대학교 대학원 : 건설환경공학부, 2017. 2. 한무영.Most of the world hydrological problems such as flooding, drought, water shortage, water pollution and groundwater depletion are all related to rainwater. By proper rainwater management (RWM), we can resolve the hydrological problems and enhance the resilience. This dissertation is to develop micro-scale hydrology modelling for multipurpose rainwater management.
Traditional methods of draining rainwater from rooftops, based on the Rainfall-Discharge (R-D) model, are challenged. By storing some of the rainfall that falls on building rooftops, flooding of nearby sewer systems can be mitigated, and the reduction of peak runoff can then calculated using the Rainfall-Storage-Discharge (R-S-D) model. The dissertation proposes and develops numerical modellings for innovative RWM systems with controlled measures as a resilient and sustainable flood mitigation approach. Conventional rainfall-runoff analysis was found to be unreasonable for micro-scale of building rooftops. In the Seoul area, 10% probability in the second quartile was set as the time distribution appropriate for determining the tank retention volume. By utilizing stored rainfall in or near a building, flooding can be further mitigated while conserving water, and the reduction of peak runoff and amount of used rainwater can also be calculated using the Rainfall-Storage-Utilization-Discharge (R-S-U-D) model. By controlled pumping, which is developed by the R-S-P-D (Rainfall-Storage-Pump-Discharge) model, runoff flows can be neutralized and thus mitigate flooding in case of heavier rainfall. Further, The R-S-I-D (Rainfall-Storage-Infiltration-Discharge) model, which incorporates with infiltration can be used for multipurpose, working towards not only further flood mitigation but also water conservation and groundwater enrichment. The reduced peak flow and increased design return period for a combination of tank volume and utilization, pumping or infiltration rates can be calculated and presented by TP, TUP, TUD, TPP, TPD, TIP, and THP curves, which can be used in the design and operation of sewer systems. Results from these models can help in designing methods to reduce the flooding risk in existing sewer systems without increasing their capacity, thus reducing expenses. Additionally, total annual water conservation and groundwater recharge in R-S-U-D and R-S-I-D systems can be calculated as a supplement of existing water supply systems.
The dissertation also develops novel modellings for RWM system to resolve the world water shortages. Getting a detailed and suitable rainfall data to have a good design of RWH system is a challenge in developing countries. In RWH system performance predictions, direct use of monthly rainfall data may lead to considerable error instead of using daily rainfall data. This dissertation proposes a simple and reasonable design method of RWH systems from available limited data. The proposed model that employs the designed rainfall which generate daily rainfall for each month with distribution of uniformly number of wet days in the last days of month as its input gives performance predictions quite similar to that of using actual daily rainfall. Further, the seasonal variatiion of rainfall was found to be other hydrological problem in RWM which caused droughts in dry sreason, and thus prohobits the use of RWM. This dissertation develops the novel variable demand model taking rainfall variance into determination of daily demand which can result an optimal performance of RWH system and ensure water saving in even dry seasons. From the model, the TRRC curves and water supply chart are developed. These curves can be used to suggest an optimal design and operation of RWM system.
The developed modellings in the dissertation can be used to resolve the current world water shortage problem and the mitigation of urban flooding, which are working towards increasing the resilience of existing systems against urbanization and climate change, and thus resulting in a solution for Sustainable Development Goals (SDGs 6 and 11).CHAPTER I. INTRODUCTION 1
1.1. Background 1
1.2. The objectives of this dissertation 8
1.3. Dissertation Structure 9
REFERENCES 11
CHAPTER II. REVIEW ON CONVENTIONAL AND MICRO-SCALE HYDROLOGY MODELLING 16
2.1. What is hydrology 16
2.1.1. Conventional Hydrology and Micro-scale Hydrology 16
2.2. Hydrology modelling 19
2.3. Review of conventional hydrology modelling 20
2.4. Situation of micro-scale rainwater management 24
2.5. Review on micro-scale rainwater management hydrology modelling 26
2.5.1. Rainwater management for flood mitigation 26
2.5.2. Rainwater management for water conservation 29
2.6. Summary 31
REFERENCES 35
CHAPTER III. RAINWATER MANAGEMENT FOR FLOOD MITIGATION 41
3.1. Introduction 42
3.2. Design rainfall analysis for flood mitigation 45
3.2.1. Design Storm frequency. 45
3.2.2. Duration of rainfall. 46
3.2.3. Design Rainfall distribution. 48
3.2.3.1. Review on design rainfall temporal distribution methods 49
3.2.3.2. Decision of design rainfall in micro-scale RWM system 55
3.3. Runoff analysis 63
3.4. Rainfall-Storage-Utilization-Discharge (R-S-U-D) model 67
3.4.1. Design of R-S-U-D system 67
3.4.2. Methodology of the R-S-U-D model development 68
3.4.3. Results and Discussions 70
3.5. Rainfall-Storage-Pump-Discharge (R-S-P-D) model 79
3.5.1. Design of R-S-P-D system 79
3.5.2. Methodology of the R-S-P-D model development 80
3.5.3. Results and Discussions 84
3.6. Rainfall-Storage-Infiltration-Discharge (R-S-I-D) model 89
3.6.1. Design of the R-S-I-D system 89
3.6.2. Methodology of the R-S-I-D model development 90
3.6.3. Results and Discussions 96
3.7. Summary 106
REFERENCES 108
CHAPTER IV. RAINWATER MANAGEMENT FOR WATER CONSERVATION 110
4.1. Introduction 111
4.2. Design RWM system for water conservation from limited rainfall data 112
4.2.1. Introduction 112
4.2.2. Rainwater harvesting system performance determination (steady demand model) 113
4.2.3. Comparison of actual daily rainfall data and monthly data 117
4.2.4. Proposal of simple and reasonable design method of RWH system from limited rainfall (monthly) data. 121
4.3. Variable demand model 133
4.3.1. Introduction 133
4.3.2. Methodology of the variable demand development 133
4.3.3. Results and Discussions 138
4.4. Summary 144
REFERENCES 145
CHAPTER V. CONCLUSIONS AND RECOMMENDATIONS 147
5.1. CONCLUSIONS 147
5.2. RECOMMENDATIONS FOR FURTHER STUDY 153Docto
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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