title: Target separation of arsenic from contaminated raw water

authors: Aremu, James Oyediji

subjects: arsenic

abstract: Arsenic is known to be one of the most toxic and carcinogenic elements known to have affected millions of people worldwide. Arsenic in surface and groundwater originates from both natural and anthropogenic sources. Prolonged exposure to arsenic can lead to skin disease, cancer, diabetes and cardiovascular disease. This thesis investigates target separation of arsenic from contaminated water using the adsorption and coagulation/flocculation/dissolved air flotation (C/F/DAF) processes. 
DMI-65, a silica based catalytic media was used as an adsorbent to investigate As (III) and As (V) removal from a contaminated drinking water. Batch adsorption studies were conducted at different pH (5, 6, 7 and 8.5) to determine adsorption kinetics. Equilibrium was achieved after 6 hours of contact time and experimental data were best fitted to the pseudo second-order kinetic model for As (III) and As (V). The adsorption data were best fitted to Langmuir isotherm models and the maximum adsorption capacity of DMI-65 for As (III) and As (V) were estimated to be 0.318 mg/g and 0.237 mg/g respectively. Thermodynamics studies revealed that adsorption capacity and arsenic removal percentage using DMI-65 increased with increase in temperature. The adsorption process can be attributed to physisorption as a result of Van der Waals interaction at the surface of the adsorbent. Regeneration and reusability of a media is an important economic factor. DMI-65 was able to demonstrate its ability to regenerate after several cycles using sodium hydroxide (NaOH) and performed well over a wide pH range. The maximum removal efficiency for As (III) was 96.55 % at pH 5 and 90.40 % for As (V) at pH 8.5. 
A continuous adsorption study was conducted in a fixed-bed column to remove arsenic from the Waikato River using DMI-65. The dynamic adsorption capacity and breakthrough time was well predicted by Thomas and Yoon-Nelson models. The maximum adsorption capacity was found to be 11.96 mg/g using DMI-65 as adsorbent for initial concentration, flowrate and pH of ~ 13.00 – 20.00 µg/L, 20 mL/min and 5, respectively. Results obtained showed that DMI-65 is effective in removing arsenic from contaminated drinking water. It is also effective in reducing turbidity but fouling of the adsorption column is a major drawback and leads to increased pressure drop in the fixed-bed column. 
Competing ions in the form of organic anions such as nitrate (NO₃⁻), silicate (SiO₄⁴⁻), sulfate (SO₄²⁻), bicarbonate (CO₃²⁻) and phosphate (H₂PO₄⁻) are known to interfere with arsenic removal in natural waters. This interference is also influenced by the pH of the solution and anionic concentration. The study was conducted at pH levels (5 – 9) and anionic concentration strength (1, 5 and 10 mM). The most significant interference with the removal of As (V) by polyaluminium chloride (PAC) occurred in the presence of phosphate at pH 6 with a removal rate of 5.52 % at 10 mM phosphate concentration. Overall, the major impact of the competing anions on As (V) removal followed the following order of H₂PO₄⁻ > CO₃²⁻ > NO₃⁻ > SO₄²⁻.
Target separation of arsenic from other contaminants was investigated in a two-stage C/F/DAF process. The results of this study indicated that increase in flotation time (10 – 30 minutes) and saturation pressure (2 – 4 bar) did not result in any significant increase in arsenic removal efficiency. Turbidity removal efficiency was poor at pH 5 and 6 despite recording higher arsenic removal efficiency. The first stage DAF process showed that 88.10 % of arsenic and 3.44 % turbidity removal efficiency was achieved using 9.4 mg/L of PAC at pH 6. Increasing the pH of the remaining solution to 8 in the second-stage DAF process resulted in 83.55 % arsenic removal and 64.08 % turbidity removal after adding 0.47 mg/L PAC. These findings showed that the amount of arsenic leaving the water treatment plant (WTP) to the wastewater treatment plant (WWTP) can be reduced from the current 0.942 kg/day to 0.16 kg/day. This represents an overall reduction of 83.01 % in the amount of arsenic that would have end up in the biosolids thereby making it unfit for agricultural purposes. This result showed that arsenic can successfully be separated from other contaminants in a two-stage C/F/DAF process by change in pH from 6 to 8 and under optimised operating conditions.

text: Target separation of arsenic from contaminated raw water Arsenic is known to be one of the most toxic and carcinogenic elements known to have affected millions of people worldwide. Arsenic in surface and groundwater originates from both natural and anthropogenic sources. Prolonged exposure to arsenic can lead to skin disease, cancer, diabetes and cardiovascular disease. This thesis investigates target separation of arsenic from contaminated water using the adsorption and coagulation/flocculation/dissolved air flotation (C/F/DAF) processes. 
DMI-65, a silica based catalytic media was used as an adsorbent to investigate As (III) and As (V) removal from a contaminated drinking water. Batch adsorption studies were conducted at different pH (5, 6, 7 and 8.5) to determine adsorption kinetics. Equilibrium was achieved after 6 hours of contact time and experimental data were best fitted to the pseudo second-order kinetic model for As (III) and As (V). The adsorption data were best fitted to Langmuir isotherm models and the maximum adsorption capacity of DMI-65 for As (III) and As (V) were estimated to be 0.318 mg/g and 0.237 mg/g respectively. Thermodynamics studies revealed that adsorption capacity and arsenic removal percentage using DMI-65 increased with increase in temperature. The adsorption process can be attributed to physisorption as a result of Van der Waals interaction at the surface of the adsorbent. Regeneration and reusability of a media is an important economic factor. DMI-65 was able to demonstrate its ability to regenerate after several cycles using sodium hydroxide (NaOH) and performed well over a wide pH range. The maximum removal efficiency for As (III) was 96.55 % at pH 5 and 90.40 % for As (V) at pH 8.5. 
A continuous adsorption study was conducted in a fixed-bed column to remove arsenic from the Waikato River using DMI-65. The dynamic adsorption capacity and breakthrough time was well predicted by Thomas and Yoon-Nelson models. The maximum adsorption capacity was found to be 11.96 mg/g using DMI-65 as adsorbent for initial concentration, flowrate and pH of ~ 13.00 – 20.00 µg/L, 20 mL/min and 5, respectively. Results obtained showed that DMI-65 is effective in removing arsenic from contaminated drinking water. It is also effective in reducing turbidity but fouling of the adsorption column is a major drawback and leads to increased pressure drop in the fixed-bed column. 
Competing ions in the form of organic anions such as nitrate (NO₃⁻), silicate (SiO₄⁴⁻), sulfate (SO₄²⁻), bicarbonate (CO₃²⁻) and phosphate (H₂PO₄⁻) are known to interfere with arsenic removal in natural waters. This interference is also influenced by the pH of the solution and anionic concentration. The study was conducted at pH levels (5 – 9) and anionic concentration strength (1, 5 and 10 mM). The most significant interference with the removal of As (V) by polyaluminium chloride (PAC) occurred in the presence of phosphate at pH 6 with a removal rate of 5.52 % at 10 mM phosphate concentration. Overall, the major impact of the competing anions on As (V) removal followed the following order of H₂PO₄⁻ > CO₃²⁻ > NO₃⁻ > SO₄²⁻.
Target separation of arsenic from other contaminants was investigated in a two-stage C/F/DAF process. The results of this study indicated that increase in flotation time (10 – 30 minutes) and saturation pressure (2 – 4 bar) did not result in any significant increase in arsenic removal efficiency. Turbidity removal efficiency was poor at pH 5 and 6 despite recording higher arsenic removal efficiency. The first stage DAF process showed that 88.10 % of arsenic and 3.44 % turbidity removal efficiency was achieved using 9.4 mg/L of PAC at pH 6. Increasing the pH of the remaining solution to 8 in the second-stage DAF process resulted in 83.55 % arsenic removal and 64.08 % turbidity removal after adding 0.47 mg/L PAC. These findings showed that the amount of arsenic leaving the water treatment plant (WTP) to the wastewater treatment plant (WWTP) can be reduced from the current 0.942 kg/day to 0.16 kg/day. This represents an overall reduction of 83.01 % in the amount of arsenic that would have end up in the biosolids thereby making it unfit for agricultural purposes. This result showed that arsenic can successfully be separated from other contaminants in a two-stage C/F/DAF process by change in pH from 6 to 8 and under optimised operating conditions.

year: 2020

title: Protracted armed conflicts, invisible civilian Suffering and international law (II)

authors: Alvarez-Jimenez, Alberto

abstract: The United Nations Security Council receives communications from Israel and Palestine almost weekly, telling the story of their civilians’ indescribable affliction. Fifty were sent from August 2013 to July 2014 – the 65th and 66th years of the conflict.¹ In one letter after another, both states expressed not a single word of concern for the other’s civilians.

text: Protracted armed conflicts, invisible civilian Suffering and international law (II) The United Nations Security Council receives communications from Israel and Palestine almost weekly, telling the story of their civilians’ indescribable affliction. Fifty were sent from August 2013 to July 2014 – the 65th and 66th years of the conflict.¹ In one letter after another, both states expressed not a single word of concern for the other’s civilians.

year: 2018

title: Decolonisation as a social change framework and its impact on the development of Indigenous-based curricula for Helping Professionals in mainstream Tertiary Education Organisations

authors: Moeke-Pickering, Taima Materangatira

subjects: Indigenous Education

abstract: This research examined the social and political approaches that Indigenous peoples undertook to situate Indigenous-based education programmes in mainstream post-secondary/tertiary education organisations. Indigenous-based helping programmes assist to progress Indigenous aspirations for self-determination and are sites that center Indigenous worldviews. A decolonisation analysis framework that is embedded in the curriculum deepens students’ understanding about the impacts of imperialism, colonisation and post colonial issues. This thesis involved researching two Indigenous-based programmes that are based within mainstream tertiary institutes. The first is the Te Whiuwhiu o te Hau Maori Counselling degree programme which is based at the Waikato Institute of Technology (WINTEC) in Hamilton, Aotearoa, New Zealand. The other is the Native Human Services Social Work degree programme which is based at Laurentian University in Sudbury, Ontario, Canada. I start this thesis with “opening the circle” and situating the context for my research. Next is the literature review chapter. This chapter provides a review of decolonisation-colonisation, decolonisation frameworks within Indigenous education, self-determination and Indigenous peoples, and Maori and Native self-determination strategies relevant to health and education. I used a case study method combined with an Indigenous methodology to guide the research. This involved gathering key pieces of information as well as interviewing participants (graduates, tutors/faculty/developers) from each programme. In chapter four is the Te Whiuwhiu o te Hau case study and in chapter five is found the Native Human Services case study. Each case study covers pre-colonial and colonisation contexts and examines assimilative legislation on Indigenous education and health. The backgrounds of social work and counselling, Native social work and Maori counselling are also presented. In the case studies is the background and rationale for the development of each programme, as well as pertinent information on the course content. Chapter six presents on the findings and conclusion and chapter seven “closes the circle”. The main findings highlighted that Indigenous curricula and pedagogies embrace Indigenous theories and discourse relevant to the helping practice fields. Secondly, each programme fosters students to make positive changes for themselves, for their communities, and for their professions. Another finding is that faculty/tutors promote an inclusive Indigenous pedagogy in the classroom that incorporates cultural ceremonies, encourage personal introspection, builds cultural and professional skills, and teaches critical education. Both programmes reflected a pedagogy that taught students to counter negative narratives while instilling a critical analysis of decolonisation and colonisation. I propose that a decolonisation analysis is both a reflective and healing tool, in that students are provided with the hard evidence about their histories and what happened to their communities. I contend that Indigenous-based programmes contribute to the continuity of Indigenous culture and wellbeing of their communities and, that they play a vital role in advancing Indigenous education priorities.

text: Decolonisation as a social change framework and its impact on the development of Indigenous-based curricula for Helping Professionals in mainstream Tertiary Education Organisations This research examined the social and political approaches that Indigenous peoples undertook to situate Indigenous-based education programmes in mainstream post-secondary/tertiary education organisations. Indigenous-based helping programmes assist to progress Indigenous aspirations for self-determination and are sites that center Indigenous worldviews. A decolonisation analysis framework that is embedded in the curriculum deepens students’ understanding about the impacts of imperialism, colonisation and post colonial issues. This thesis involved researching two Indigenous-based programmes that are based within mainstream tertiary institutes. The first is the Te Whiuwhiu o te Hau Maori Counselling degree programme which is based at the Waikato Institute of Technology (WINTEC) in Hamilton, Aotearoa, New Zealand. The other is the Native Human Services Social Work degree programme which is based at Laurentian University in Sudbury, Ontario, Canada. I start this thesis with “opening the circle” and situating the context for my research. Next is the literature review chapter. This chapter provides a review of decolonisation-colonisation, decolonisation frameworks within Indigenous education, self-determination and Indigenous peoples, and Maori and Native self-determination strategies relevant to health and education. I used a case study method combined with an Indigenous methodology to guide the research. This involved gathering key pieces of information as well as interviewing participants (graduates, tutors/faculty/developers) from each programme. In chapter four is the Te Whiuwhiu o te Hau case study and in chapter five is found the Native Human Services case study. Each case study covers pre-colonial and colonisation contexts and examines assimilative legislation on Indigenous education and health. The backgrounds of social work and counselling, Native social work and Maori counselling are also presented. In the case studies is the background and rationale for the development of each programme, as well as pertinent information on the course content. Chapter six presents on the findings and conclusion and chapter seven “closes the circle”. The main findings highlighted that Indigenous curricula and pedagogies embrace Indigenous theories and discourse relevant to the helping practice fields. Secondly, each programme fosters students to make positive changes for themselves, for their communities, and for their professions. Another finding is that faculty/tutors promote an inclusive Indigenous pedagogy in the classroom that incorporates cultural ceremonies, encourage personal introspection, builds cultural and professional skills, and teaches critical education. Both programmes reflected a pedagogy that taught students to counter negative narratives while instilling a critical analysis of decolonisation and colonisation. I propose that a decolonisation analysis is both a reflective and healing tool, in that students are provided with the hard evidence about their histories and what happened to their communities. I contend that Indigenous-based programmes contribute to the continuity of Indigenous culture and wellbeing of their communities and, that they play a vital role in advancing Indigenous education priorities.

year: 2010