published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

De-inking sludge generated from pulp and paper industry is considered hazardous since it may contain heavy metals such as Cd, Cr, and Pb. Hence, the de-inking sludge needs to be treated before being disposed of. Sludge combustion is a proven disposal technology, which generates fly ash containing a portion of the heavy metals that may leach out under uncontrolled conditions. The aim of this thesis is to implement a new multi-zone temperature combustion technique (Low-High-Low temperature combustion, LHL) to help contain and immobilize the heavy metals within fly ash particles. During the LHL, the waste will be initially fed into a low-temperature zone (<1100 K) and then subjected to the high-temperature treatment (~1480 K) that will be followed by another low-temperature zone (~1100 K). / This dissertation describes the detailed design and construction of a novel pilot-scale combustion facility, called the Multi-Mode Combustion Facility (MCF), used as a multidisciplinary research tool for investigating the thermal remediation of contaminated solid residues. The MCF is capable of operating in two different modes: Fluidized-Bed combustion mode (FBC) and Single burner furnace mode (SBF). However, this project focuses on the FBC mode (minimum fluidization velocity of 0.42 m/s and bed temperature of 1073 K). / This research compares the combustion characteristics of de-inking sludge obtained in the LHL and in the conventional combustion techniques. The following properties of particulates were studied: morphological evolution of solid particles, structural porosity, metals interactions with fly ash particles, and leachability. / The LHL's final supermicron spherical fly ash went through a molten phase with submicron particles attached to the fly ash particles surfaces. Thus, reducing its porosity to 19%. However, the amorphous final fly ash obtained in the conventional technique reveals 32% porosity. It was found that the physical characteristics of the final LHL's fly ash are the main cause for the reduced heavy metals leachability rates of 0.18, 0.046, and 0.92% for Cd, Cr, and Pb, respectively. The conventional technique had 53.28, 16.79, and 5.20% of Cd, Cr, and Pb respectively, leaching out due to the high porosity percentages. In conclusion, the LHL technique allows for controlling the heavy metals emission from FBCs, while using a waste to energy approach and maintaining environmentally acceptable gas emission levels.

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Chan Chik-yu. / Thesis submitted in: December 1998. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1999. / Includes bibliographical references (leaves 128-152). / Abstract also in Chinese. / Acknowledgments --- p.i / Abstract --- p.ii / Table of Contents --- p.vi / List of Tables --- p.ix / List of Figures --- p.xi / List of Plates --- p.xiii / Chapter Chapter 1 --- INTRODUCTION --- p.1 / Chapter 1.1 --- Fly Ash --- p.1 / Chapter 1.1.1 --- Formation of fly ash --- p.1 / Chapter 1.1.2 --- Physical and chemical properties of fly ash --- p.1 / Chapter 1.1.3 --- Disposal --- p.3 / Chapter 1.2 --- Problems Associated with the Reclamation of Fly Ash --- p.5 / Chapter 1.2.1 --- Physical problems --- p.6 / Chapter 1.2.2 --- Nutrient problems --- p.6 / Chapter 1.2.3 --- Toxicity problems --- p.6 / Chapter 1.2.4 --- Biological problems --- p.7 / Chapter 1.3 --- Ecological Considerations on Wasteland Reclamation --- p.7 / Chapter 1.3.1 --- Ecological basis --- p.7 / Chapter 1.3.2 --- Problems of ecosystem development and its treatments --- p.11 / Chapter 1.4 --- Obj ectives of the Present Study --- p.17 / Chapter Chapter 2 --- EDAPHOLOGICAL CHARACTERISTICS OF FLY ash and vegetation composition on fly ASH LAGOON --- p.23 / Chapter 2.1 --- Introduction --- p.23 / Chapter 2.2 --- Materials and Methods --- p.24 / Chapter 2.2.1 --- Site description --- p.24 / Chapter 2.2.2 --- Collection of fly ash and soil samples --- p.25 / Chapter 2.2.3 --- Physical analysis --- p.26 / Chapter 2.2.4 --- Chemical analysis --- p.26 / Chapter 2.2.5 --- Vegetation analysis --- p.27 / Chapter 2.2.6 --- Statistical analysis --- p.27 / Chapter 2.3 --- Results and Discussion --- p.28 / Chapter 2.3.1 --- Physical properties --- p.28 / Chapter 2.3.2 --- Chemical properties --- p.33 / Chapter 2.3.3 --- Vertical ash profile --- p.42 / Chapter 2.3.4 --- Vegetation survey --- p.48 / Chapter 2.4 --- Conclusions --- p.58 / Chapter Chapter 3 --- GREENHOUSE PLANT SELECTION AND AMELIORATION TRIALS ON LAGOONED FLY ASH --- p.60 / Chapter 3.1 --- Introduction --- p.60 / Chapter 3.2 --- Materials and Methods --- p.62 / Chapter 3.2.1 --- Collection of lagooned fly ash and planting materials --- p.62 / Chapter 3.2.2 --- Plant selection trial --- p.63 / Chapter 3.2.3 --- Amelioration trials --- p.66 / Chapter 3.2.4 --- Statistical analysis --- p.68 / Chapter 3.3 --- Results and Discussion --- p.68 / Chapter 3.3.1 --- Plant selection trial --- p.68 / Chapter 3.3.2 --- Amelioration trials --- p.75 / Chapter 3.4 --- Conclusions --- p.83 / Chapter Chapter 4 --- LEACHING OF SOLUBLE SALTS AND BORON FROM LAGOONED FLY ASH --- p.84 / Chapter 4.1 --- Introduction / Chapter 4.2 --- Materials and Methods --- p.86 / Chapter 4.2.1 --- Setup of column --- p.86 / Chapter 4.2.2 --- Leaching regimes --- p.86 / Chapter 4.2.3 --- Growth of ryegrass on leached ashes --- p.89 / Chapter 4.2.4 --- Chemical analysis on ashes --- p.89 / Chapter 4.2.5 --- Statistical analysis --- p.89 / Chapter 4.3 --- Results and Discussion --- p.90 / Chapter 4.3.1 --- Leaching of soluble salts and B --- p.90 / Chapter 4.3.2 --- Plant growth in leached ashes --- p.101 / Chapter 4.4 --- Conclusions --- p.105 / Chapter Chapter 5 --- EFFECTS OF ORGANIC AMENDMENTS ON plant growth on pre-leached fly ash --- p.106 / Chapter 5.1 --- Introduction --- p.106 / Chapter 5.2 --- Materials and Methods --- p.108 / Chapter 5.2.1 --- Collection of materials --- p.108 / Chapter 5.2.2 --- Chemical analysis of planting media --- p.108 / Chapter 5.2.3 --- Plant growth experiment --- p.109 / Chapter 5.2.4 --- Statistical analysis --- p.110 / Chapter 5.3 --- Results and Discussion --- p.110 / Chapter 5.3.1 --- Chemical properties --- p.110 / Chapter 5.3.2 --- Plant growth on organic-amended ash --- p.116 / Chapter 5.3.3 --- Plant elemental uptake --- p.118 / Chapter 5.4 --- Conclusions --- p.123 / Chapter Chapter 6 --- GENERAL CONCLUSIONS --- p.125 / References --- p.128

Thesis submitted in fulfilment of requirements for the degree Magister Technologiae: Chemical Engineering In the FACULTY OF ENGINEERING At the CAPE PENINSULA UNIVERSITY OF TECHNOLOGY, 2012 / The generation of electricity from coal in South Africa results in millions of tons of fly ash being produced each year. Less than 10 % of the fly ash generated is being used constructively and the remaining unused ash is currently inducing disposal and environmental problems. Intensive research on the utilisation of fly ash has been conducted either to reduce the cost of disposal or to minimise its impact on the environment. It has been shown that South African fly ash can be used as a feedstock for zeolite synthesis due to its compositional dominance of aluminosilicate and silicate phases. Most of the studies conducted on zeolite synthesis using South African fly ash are performed on small laboratory scale. Therefore, production of zeolites on an industrial/pilot plant scale would, in addition to producing a valuable product, help abate the pollution caused by the disposal of fly ash in the country. This research focuses on the investigation of the scale-up opportunity of zeolite synthesis from South African fly ashes with the view of understanding the effects of some reactor and operational parameters on the quality of the zeolite produced. Two types of zeolites (zeolite Na-P1 and zeolite A) were synthesised via two different routes in this study: (1) a two stage hydrothermal synthesis method (zeolite Na-P1) and (2) alkaline fusion prior to hydrothermal synthesis (zeolite A). The synthesis variables evaluated in this study were; the effect of impeller design and agitation rates during the aging step (zeolite Na-P1) using three different impellers (anchor, 4-flat-blade and Archimedes screw impeller) at three agitation speeds (150, 200 and 300 rpm), the effect of fly ash composition and solvents (water sources) on the phase purity of both zeolite Na-P1 and zeolite A, and the effect of the hydrothermal reaction time during the synthesis of zeolite Na-P1 using low amorphous phase fly ash i.e. aging time (12-48 hours) and hydrothermal treatment time (12-48 hours). The raw materials (fly ashes from Arnot, Hendrina, Tutuka, Lethabo and Matla power stations) and the synthesised zeolite product were characterised chemically, mineralogically and morphologically by X-ray fluorescence spectrometry, X-ray powder diffraction and scanning electron microscopy. Other characterisation techniques used in the study were 1) Fourier transform infrared spectroscopy to provide structural information and also monitor the evolution of the zeolite crystals during synthesis and 2) inductively coupled plasma atomic emission (ICP-AES) and mass spectrometry for multi-elemental analysis of the synthesis solution and the solvents used in this study. The experimental results demonstrated that the phase purity of zeolite Na-P1 was strongly affected by agitation and the type of impeller used during the aging step of the synthesis process. A high crystalline zeolite Na-P1 was obtained with a 4-flat-blade impeller at a low agitation rate of 200 rpm. Although a pure phase of zeolite Na-P1 was obtained at low agitation rates, the variation in the mineralogy of the fly ash was found to affect the quality of the zeolite produced significantly. The results suggested that each batch of fly ash would require a separate optimisation process of the synthesis conditions. Therefore, there is a need to develop a database of the synthesis conditions for zeolite Na-P1 based on the fly ash composition. As a consequence, the scale-up synthesis of zeolite Na-P1 would require step-by-step optimisation of the synthesis conditions, since this zeolite was sensitive to the SiO2/Al2O3 ratio, agitation and the mineralogy of the fly ash. On the other hand, zeolite A synthesis had several advantages over zeolite Na-P1. The results suggested that a pure phase of zeolite A can be produced at very low reaction temperature (i.e. below 100 °C, compared to 140 °C for zeolite Na-P1), shorter reaction times (i.e. less than 8 hours compared to 4 days for zeolite Na-P1), with complete dissolution of fly ash phases and more importantly less sensitive to the SiO2/Al2O3 ratio of the raw materials. The zeolite A synthesis process was found to be more robust and as a result, it would be less rigorous to scale-up despite the energy requirements for fusion. This study showed for the first time that different impeller designs and agitation during the aging step can have a profound impact on the quality of the zeolite produced. Therefore, it is not only the hydrothermal synthesis conditions and the molar regime but also the dissolution kinetics of the feedstock that influence the outcome of the zeolite synthesis process. This study has also shown for the first time that a pure phase of zeolite A can be synthesised from various sources of South African fly ash containing different mineralogical and chemical compositions via the alkali fusion method under the same synthesis conditions. Therefore, the effective zeolitisation of fly ash on a large scale would assist to mitigate the depletion of resources and environmental problems caused by the disposal of fly ash.

A site-specific artificial stream system receiving selected levels of fly ash, heavy metals, or sulfates was compared to a natural stream (Adair Run) influenced by effluent from the fly ash settling basin at Glen Lyn, Virginia. Aufwuchs communities colonizing glass microscope slides were monitored for dry weights, ash-free dry weights, chlorophylls, ATP, and 14-carbon and 35-sulfate assimilation rates. Productivity appeared to be enhanced in Adair Run due to increased concentrations of sulfates (150 mg/l), and temperature (delta T=4. 5 C) in the ash basin effluent. A recovery response was observed following termination of basin operation. Artificial streams receiving selected concentrations of fly ash at low TSS (8.0-25 mg/l) exhibited no inhibition for all parameters except chlorophyll a and ATP. Higher levels (80-100 mg/l) depressed all aufwuchs parameters except AFDW within six days. Six heavy metals (Cd, Cr, Cu, Ni, Pb, Zn), when collectively pumped into artificial streams at concentrations modeling the ash basin effluent effectively lowered productivity parameters. This was followed by a slow recovery response. Aufwuchs demonstrated an ability to bioconcentrate heavy metals from ambient water. Streams dosed with sulfates demonstrated a stimulation response at concentrations modeling the Adair Run system. Current U.S. EPA effluent guidelines for fly ash (30 mg/l maximum weekly average; 100 mg/l maximum) are evaluated concerning the degree of protection afforded primary producers of aquatic receiving systems. / Master of Science

Coal-fired power plants constitute a significant source of energy production for the United States, and are projected to do so for decades to come. Most of the scrutiny coal-fired power plants receive is in the form of environmental concerns regarding green house gas emissions of carbon dioxide, sulfur dioxide, and others. It is known that coal fly ash released through the stacks of coal power plants contains concentrated levels of naturally-occurring radiation, such as Radium-226. However, since the source of radiation is natural and the activity levels are low, there are no nuclear regulatory requirements imposed on coal plants. The focus of this study was to use the Nuclear Regulatory Commission’s (NRC) facility release criteria to determine whether the concentration of naturally occurring Radium-226 present in soil surrounding the Centralia Power Plant is elevated relative to soil collected 80 kilometers away. The non-parametric Wilcoxon Rank Sum test was used to compare twenty-eight soil samples collected within 3.4 kilometers of the Centralia Power Plant stacks against an equal number of reference samples collected in Port Orchard, Washington. It was determined that the average concentration of Radium-226 in soil near the power plant was 1.59 pCi/g, while the average concentration in reference soil was 0.59 pCi/g. The study suggests that the area around the power plant would fail to pass the release criteria of a NRC Multi-Agency Radiation Survey and Site Investigation (MARSSIM) Class 3 survey unit. If it is true that coal fired power plants increase background radiation levels measurably, but not at a level sufficient to cause alarm, it may be sensible to revise the strict emissions standards for nuclear facilities or increase requirements for utilities other than nuclear. / Graduation date: 2012