Development and Application of Calcium-Based Capping Material for Physicochemical Improvement of the Coastal Contaminated Sediments
- Abstract
- The coastal area has the most complicated and valuable ecosystem on Earth due to the interaction of land and sea. However, the pollution intensity of coastal sediment has increased due to the accumulation of highly concentrated organic matter and various contaminants. This phenomenon causes environmental problems and devastates the coastal benthic environment. Among various research to improve contaminated coastal sediment through dredging and in-situ capping, calcium-based capping material (CM) is highly effective, and especially, granulated coal ash using coal fly ash and cement has been actively researched. The utilization of cement causes 2nd environmental problems and has low cost-effectiveness. Therefore, new calcium-based CM without low environmental problems is required for the remediation of contaminated coastal sediment.
The industrial by-products, coal bottom ash (CBA) and oyster shell (OS) were researched for the development of new CM in this dissertation. CBA and OS have high silica and calcium contents, and are used in concrete production as aggregates and admixtures. Thus, it was hypothesized that the mixture of CBA and OS could be calcium-based CM without cement. The dissertation aimed to develop calcium-based CM using CBA and OS, and evaluate the effects on the improvement of contaminated coastal sediment.
To evaluate the strength and nutrient fixation ability of the mixture of CBA and OS, compressive strength, isotherm adsorption, and up-flow filtration experiments were conducted. The mixing ratio of 1:1 in CBA and OS (GBO11) showed 0.93 Mpa, showing enough strength as CM. GBO11 followed Redlich-Peterson adsorption model, and the maximum P adsorption amount by GBO11 was 1.360 mg/g. Based on the property of GBO11, it can be suggested that proper amount of GBO11 is 114 kg/m2 on the contaminated coastal sediment for remediation.
In addition, GBO11 aggregated sediment particles, increasing the permeability by 5 times higher than control. Calcium eluted from pyrolyzed OS at 800°C increased viscosity and sediment particle size, decreasing suspended sediment flux by 28% compared to control. And calcium formed a calcium-silicate-hydrate (CSH) and effective bridge, increasing the bonding force between sediment particles. The suitable mixing ratio of CBA and OS for sediment remediation was 1:1 (GBO11), and the remediation effect of GBO11 was maximized at higher water temperatures.
Considering the aforementioned results, GBO11 has enough mechanical strength and is expected to reduce high nutrient concentration. Eluted calcium will also decrease pollution release by increasing sediments' erosion resistance. Increased sediment strength can provide stabilized habitat for marine benthic flora and fauna. In addition, low heavy metal elution is expected from GBO11, indicating that GBO11 will be an environmentally friendly CM. Therefore, GBO11 can be utilized as an effective in-situ reactive CM.
The CBA and OS can be reintroduced into the resource circulation through the GBO11 utilization. Field observation, biological evaluation, and cost-effectiveness of GBO11 should be investigated to utilize GBO11. Thus, a multidisciplinary approach should be conducted in the future for the utilization of GBO11
- Issued Date
- 2023
- Awarded Date
- 2023-02
- Type
- Dissertation
- Publisher
- 부경대학교
- Alternative Author(s)
- Ilwon Jeong
- Affiliation
- 부경대학교 대학원
- Department
- 대학원 해양공학과
- Advisor
- 김경회
- Table Of Contents
- 1. Introduction 1
1.1 Research background 1
1.1.1 Importance of the coastal area 1
1.1.2 Deterioration of coastal sediment 2
1.1.3 Remediation methods for contaminated coastal sediments 4
1.1.4 Classification of in-situ capping material 5
1.1.5 Remediation effects of industrial by-products CM 8
1.1.6 Industrial by-products for new CM development 10
1.2 Purpose and approach of dissertation 12
1.3 Organization of dissertation 13
2. Physicochemical properties of coal bottom ash and oyster shell 16
2.1 Overview 16
2.2 Collection and pretreatment of industrial by-products 17
2.2.1 Coal bottom ash 17
2.2.2 Oyster shells 17
2.3 Physicochemical properties of coal bottom ash and oyster shell 18
2.3.1 TG-DTA 18
2.3.2 XRD and XRF 20
2.3.3 Water content and loss on ignition 25
2.3.4 Particle size distribution and specific surface area 27
2.3.5 Sorption isotherm 29
2.3.6 Cumulative pore surface and volume with pore width 32
2.4 Conclusion 35
3. Development and physicochemical properties of CM 37
3.1 Overview 37
3.2 Phosphorous adsorption mechanism of CBA 38
3.2.1 Background of adsorption isotherm 38
3.2.2 Adsorbent and phosphorus solution 42
3.2.3 Experiment scheme and measurement 42
3.2.4 X-ray absorption fine structure analysis 43
3.2.5 Changes in pH, ORP, and PO4-P concentration 44
3.2.6 Phosphate fixation 48
3.2.7 Suitability of adsorption isotherm model 50
3.3 Development and strength in a mixture of CBA and OS 55
3.3.1 Pretreatment of materials 55
3.3.2 Unconfined uniaxial compression test 56
3.3.3 Result of XRD and XRF 58
3.3.4 Change of compressive strength and displacement 60
3.4 Phosphorus adsorption mechanism of developed CM 62
3.4.1 Preparation of adsorbent and phosphorus solutions 62
3.4.2 Adsorption isotherm experiment 63
3.4.3 Changes in pH, ORP, and PO4-P concentration 63
3.4.4 Suitability of adsorption isotherm 67
3.5 Quantitative evaluation for P fixation ability in GBO11 72
3.5.1 Production of GBO11 72
3.5.2 Up-flow column filtration experiment 72
3.5.3 Changes in pH, ORP, and PO4-P 74
3.5.4 Estimation of P fixation amount by GBO11 77
3.5.5 Feasibility in the application of GBO11 78
3.6 Conclusion 81
4. Effects of calcium on physicochemical changes of coastal sediment 82
4.1 Overview 82
4.2 Permeability improvement of coastal sediment by GBO11 83
4.2.1 Preparation of coastal sediment and GBO11 83
4.2.2 Permeability experiment 83
4.2.3 Changes in permeability and water retention ability 86
4.2.4 Changes in pH, ORP, and nutrients of effluents 90
4.2.5 Changes in water content and loss on ignition 96
4.3 Suppression of coastal sediment resuspension 97
4.3.1 Preparation of experimental materials 97
4.3.2 Generation of water velocity and bottom shear stress 98
4.3.3 Relationship between suspended sediment concentration and turbidity 104
4.3.4 Experimental scheme of resuspension experiment 106
4.3.5 Distribution of water velocity and bottom shear stress 108
4.3.6 Changes in SSC and SS in an annular flume 113
4.3.7 Distribution of particle size in the resuspended sediment particle 119
4.3.8 Concentration of chemical elements 123
4.4 Effects of pyrolyzed oyster shells on the changes in coastal sediment strength 128
4.4.1 Preparation of coastal sediments, seawater, and OS 128
4.4.2 Experiment of shear strength in coastal sediment 128
4.4.3 Changes in shear strength of coastal sediment by pyrolyzed OS 131
4.4.4 Property changes in pore water and sediment 136
4.4.5 Changes in chemical components 142
4.5 Conclusion 145
5. Long-term investigation of suitable conditions for GBO11 application 147
5.1 Overview 147
5.2 Effects of GBO with different mixing ratio on remediation of coastal sediment 148
5.2.1 Collection of sediment and seawater 148
5.2.2 Preparation of GBO 150
5.2.3 Scheme of microcosm experiment 151
5.2.4 Effect of GBO on water quality in overlying water and sediment 152
5.2.5 Optimum mixing ratio of GBO for coastal sediment remediation 164
5.3 Seasonality effects of GBO11 on coastal sediment 165
5.3.1 Preparation of coastal sediment and GBO11 165
5.3.2 Scheme of microcosm experiment 166
5.3.3 Effects of water temperature in overlying and pore water 167
5.4 Conclusion 181
6. Summary and conclusion 183
References 187
Summary in Korean 207
- Degree
- Doctor
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