Hydrogeochemical modeling of the speciation and leaching of fly ash co-disposed with water, brines and organics : a case study of Sasol-Eskom coal ash disposal, South Africa.

Thesis (Ph.D.)-University of KwaZulu-Natal, Westville, 2012.Two coal utility plants in South Africa selected (one from Sasol and another from Eskom) for this study produce large volumes of fly ash (over 40 Mt from Eskom at Tutuka, and 3 Mt from Sasol Synfuels at Secunda annually), and brines as by-products during coal processing. Co-disposal of the brines and fly ashes has been a normal practice in these coal-utility plants for decades. Long-term management of fly ash is necessary and requires an understanding and knowledge of how the different waste materials interact with water and brines in different chemical situations. However the geochemistry of their interactions, the leaching and mobility of elements in these disposal systems has not been fully understood. This work gives insights into the chemical processes taking place in the brine-water/brines systems that govern the concentrations of major and minor elements in ash leachates under different environmental conditions. The possible presence of organic compounds (subsequently referred to as 'organics') in brines and their effects on the leaching chemistry of fly ash was also studied. Sustainability and long term impact of the co-disposal of fly ash and brines on the environment was studied through static (batch tests) modeling of the pH-dependent acid neutralization capacity (ANC) tests and columns modeling for dynamic leach tests. The modeling was based on experimental results from other Sasol-Eskom ashbrine project collaborators. Modeling results of the ANC tests were in good agreement with the reported experimental results, which revealed that the release trends of various elements (including trace, heavy elements and contaminants) contained in fly ash into solution is highly pH dependent. However Na, K, Mo and Li exhibited constant solubilisation which was independent of pH changes from all the scenarios. The presence of different constituents of brines subjected to ANC resulted to different ANC capacities ranging from 0.98 moles H⁺/Kg dry ash (of ash-organics mixed with Mg-brines) to 3.87 H⁺/Kg dry ash for those with the C(4) brines. As expected, those constituents from the cationic brines were found on the lower region of acid addition (in the order Mg-brines 12 (suspension in demineralised water) and the predominant cation even at this high pH is Ca²⁺ (at concentration > 0.002 mmol/L). This indicates that dissolution of CaO and formation of OH⁻ species at pH > 10 contributes to acid neutralisation capacity of both fly ashes and is the greatest contributor to the acid neutralizing capacity of both fly ashes. Two broad leaching behaviours as a function of pH were observed from the three fly ash-ASW organics-brines scenarios (i) leaching of Ca, Mg, Ni and Sr follows a cationic pattern where the concentration decreases monotonically as pH increases; (ii) leaching of Al, Fe, Ti and Zn follow an amphoteric pattern where the concentration increases at acidic and alkaline pH, although Al showed some anomaly from pH 11 where the concentration decreased with the increase in pH. Al showed an amphoteric pattern in which its release increased between pH 12.8 and 11 for all the scenarios and then decreased with decrease in pH down to neutral pH of 7. The batch leaching simulation results from hydrogeochemical modeling also showed that mineral dissolution, precipitation and new phase formation during ash-organics-brines interactions was controlled by pH. The newly formed phases however remain in equilibrium with the ash-brines-organics mixture. Each individual mineral phase dissolution/precipitation/formation system controls the concentration and speciation of the respective constituent elements as evidenced by the log C-pH diagrams obtained from the modeled scenarios. The ash-brines-organics interactions do exhibit and affect the mineralogical chemistry of fly ash. However the extent to which these interactions occur and their effect, varies from one scenario to another, and are dependent on the amounts and type of the constituent brine components. Organics do have a significant effect on dissolution characteristics of few minerals such as calcite, mullite, kaolinite, Ni₂SiO₄, and SrSiO₃ due to complexation effect. The effect is quantitatively conspicuous for calcite mineral phase and for the formation of some new phases such as Fe(OH)₃(am)-CF and portlandite. The composition of the liquid phase from acid neutralisation capacity experiments was successful.Hydrogeochemical modeling was used as a means to provide insights and understanding of the complex reactions taking place, speciation and mineralogical changes occurring. These changes would serve to predict future environmental scenarios when pH conditions change. In this study, an extension of the application field of PHREEQC hydrogeochemical code for modeling and simulation of equilibrium; kinetic and transport mechanisms associated with the interaction of water; and organics and brines with fly ash during their co-disposal is successfully demonstrated. The parameters associated with these mechanisms were used as inputs into the PHREEQC program using modified Lawrence Livermore National Laboratory (LLNL) database for inorganic brines and MINTEQ.V4 database for organics, and used to model the results of ANC test data for the fly ashes. A special reference is made to two separate modeled mineralogical ash recipes from two of the South African power utility plants' fly ash systems, namely, Tutuka and Secunda. The effects of brines in the leaching of major, minor and trace elements at various pH values and the mineralogical changes associated with the intermediate and final products from the interactions of ash-brines systems under different scenarios are qualitatively and quantatively discussed. Multiphase saturation characteristics have been determined for mineral species in contact with water and brines. The modeling results indicated that several mineral phases could be controlling the species concentration in the leachates, and the ANC and column modeling results corroborated well in many aspects with the experimental results obtained from collaborating institutions (South Africa Universities and Research institutions). In addition, application of the PHREEQC model to the ash heap under different disposal systems was carried out to predict the heap leachate composition and geochemical transformations taking place in a period of time. Pore water chemical analysis, and moisture content analysis revealed that contact of the ash with water is a crucial factor in the mobilization of the contaminants with time. Maximum weathering/dissolution of the ash is observed in the top layer (1-3) m and at the point of contact with the subsurface water level which was in good agreement with the model results. The surface layer and the very lowest layers of the dump in contact with lateral flows experience the highest degree of weathering leading to depletion of species. The geophysical transformation of fly ash was also captured through the porosity change calculations and the results revealed that geochemical reactions do affect the porosity of fly ash during the weathering processes. These modelling results were in agreement with the hydraulic tests and salt leaching tests conducted during Sasol-Eskom ashbrine project in Phase I which suggested that salts captured in the ash will become mobile and leach from the fly ash over time. The data therefore indicates that ash dumps may not act as sustainable salt sinks. These findings may have some bearing on engineering decisions on fly ash reuse. From the above observations, it is apparent that release of large quantities of the salts in the ash depends on the extent of its interaction with brines being used for irrigation or with water, either through plug-in flow after a rainfall event or contact with groundwater. The results revealed effects of brine-water contact time with fly ash, the flow volume and velocity, the pH, the degree of saturation, hydrogeology and ash heap geometry as important factors that affect fly ash transformation and weathering. Overall, the ash heap modeling enhanced the understanding of the ash-brines interactions and demonstrated that leachate composition is determined by the following factors; (i) the mass flows from the pores of fly ash, (ii) the surface dissolution of the mineral phases, (iii) the various chemical reactions involved during the ash-brine and ash-water interactions, (iv) the interactions with a gas phase (atmospheric CO₂), (v) the composition of the initial fly ash, and (vi) by the leachate flow and hydrodynamics as captured in the conceptual model. Any ash handling system should therefore be designed to take these criteria into consideration to prevent environmental contamination. The modeling results also gave indications that the ash-brine co-disposal in dry ash systems would be an unsustainable way of locking up brine salts in the long run. In this Thesis, modeling results were used to support experimental data which further reaffirmed the important role hydrogeochemical modeling plays in liquid and solid waste management. Furthermore, hydrogeochemical modeling complements the work of analytical/environmental scientists as well as guiding the future solid waste management and engineering decisions

Primary schools’ development in Somaliland – The role of Community Education Committees

The study sought to determine the methods used to participate the community in school infrastructure projects. It also examined the extent and effectiveness of the community education committee participation process. Done as a cross-sectional survey using mixed methods of inquiry, the study targeted 1002 respondents consisting of 920 headteachers and 82 officers in charge of District Education (DEOs) in Somaliland. The sample comprised 257 headteachers and 22 DEOs. Multi stage sampling was used. Purposive sampling was used to draw a sample of regions, stratified random sampling to draw a sample of headteachers while simple random sampling was used to draw a sample of DEOs. Pilot testing of the questionnaire was done on 28 headteachers. DEOs were interviewed while Headteachers filled questionnaires. Reliability of the questionnaire was ensured using Cronbach alpha. Empirical literature review, peer review and pilot testing were used to ensure validity. The response was received from 20 DEOs and 247 headteachers. Thematic analysis was used to analyse interview data collected from DEOs. Headteachers data collected by questionnaire were analysed using descriptive statistics. Participating the community in decision-making, offering free labour and and fundraising were the leading methods of participating communities in school infrastructure projects. Communities perceived full ownership of completed school infrastructure projects. Community members were satisfied with the schools‘ participation process. Most schools had realized their community participation goals. The CEC process was just one of the numerous ways the community participated in school infrastructure projects. The CEC participation method was largely working and realising its goals. More school development could be realised if the CEC participation process was further strengthened

Harnessing Social Capital for School Development: Community Participation in School Construction Projects

The study examined how communities participate in school construction projects in primary schools in Somaliland and how community participation in school construction projects influences the performance of those projects. The study used a correlational design and was undertaken as a cross-sectional survey. The target population was 920 primary school headteachers in all the 13 regions of Somaliland and 82 District Education Officers. A sample of 257 headteachers was drawn using multistage sampling where purposive sampling and stratified random sampling with replacement were used to sample headteachers while 22 DEOs were sampled using simple random sampling. Data was collected from headteachers using questionnaires and from DEOs using semi-structured interviews. The questionnaire was pilot tested on 28 headteachers. The response was received from 247 headteachers and 20 DEOs. Variables relationships were analyzed using path analysis and tested using t-tests at α = 5%. The main methods used to involve the community in primary schools’ construction projects were: involving them in decision-making processes, volunteering labour and fundraising. The study found that community participation had no significant influence on the performance of construction projects. Community participation in public primary schools in postwar Somaliland is a policy-driven initiative and a fill-gap measure of deficiencies left by the government’s low and inadequate capitation to schools. Low social capital in the communities participated in projects coupled with the costs and the downsides of the community participation process can result in a negative impact on the performance of those projects. Urban schools tend to benefit more from community participation than rural schools due to higher social capital stocks in urban communities as compared to rural communities

Lessons for School Principals from Transformational Leadership Characteristics

This study was carried out in selected public secondary schools in Kenya. It is on the realization that the work of the school Principal is not easy and many find themselves in leadership without proper preparation for the hard task. The school principals’ work is a high-stress job especially because he or she has to do virtually everything related to students, teachers, parents, subordinate staff and the community at large. This kind of leader would require extra-ordinary characteristics to be able to be successful. Majority of principals perform decimally in all the areas that spell success in secondary schools especially in discipline and academic performance. The purpose of this study was to find out how principals’ transformational leadership characteristics were correlates to effective school performance. Kouze’s and Posner’s leadership Practices Inventory(LPI)  “self” questionnaire  was used to measure  Principals’ transformational leadership style. LPI “others” was used to triangulate the principals’ response with the teachers. The target population consisted of 72 Principals in public schools and 139 principals in private schools.  There were also 1210 teachers in public secondary schools and 1500 teachers in private secondary schools in Nairobi County. The findings indicated positive correlations between the Principals’ transformational leadership characteristics with effective school performance. Keywords: Secondary schools, transformational leadership, modeling the way, inspiring a shared vision, encouraging the heart, enabling others to act. DOI: 10.7176/JEP/10-12-06 Publication date: April 30th 201

Influence of Financial Management Skills on Performance of Youth Environmental Projects: A Case of Solid Waste Management Projects in Nairobi County, Kenya

With the upsurge of unemployment, more youths are conducting garbage collection activities as an enterprise to improve their livelihood. This study examined the influence of financial management skills on performance of youth environmental projects in Nairobi County, a case of solid waste management projects. It was guided by pragmatism research paradigm adopting descriptive survey and correlational research designs. The study’s target population was 700 youth group members engaged in solid waste management projects in Nairobi County, using a sample size of 248 group members, based on Krejcie and Morgan’s sampling table. Key informants from 4 departments of Directorate of Youth affairs were purposely selected. Research instruments entailed questionnaires and interview guide. Qualitative data was analyzed and presented in narrative statements while inferential statistics were analyzed using Pearson correlation coefficient and multiple regression analysis to test hypotheses. The correlation index between financial skills and performance of youth environmental projects was positive and significant, r (247) =.525; p≤.05. This inferred that as the level of financial project management skill increases, the performance levels also increase. The T value for financial management skills was also significant; T (247) = 9.682; β= 0.724.; P≤.05. This implied that for each unit increase in financial management skills, the performance of youth environmental projects could increase by 0.724 units. This inferred the rejection of null hypothesis and the conclusion made that H1 (There is a significant influence of financial management skills on performance of youth environmental projects in Nairobi County). The researcher recommends the pulling together of a common funding accessible to all youths by the government of Kenya and a policy action by the government to incorporate youths to learn financial management skills under mentorship programs from entities dealing with environmental projects so as to incubate their skills for effective project performance

Monitoring and Evaluation Practices and Performance of livelihood ventures: Focus; Nairobi youths conservation projects, Kenya

In Kenya, youth unemployment rate is on the rise especially for urban youths, despite government’s perennial interventions and funding. This study sought to investigate on monitoring and evaluation practices and performance of livelihood ventures; focusing on youth conservation projects in Nairobi County. The study specifically focused on solid waste collection projects managed by youth groups within Nairobi residential areas; which is among the conservation projects that attract government funding through the Directorate of youth. The study had a target population of 700 youth group members and a Study sample of 248 youths. Key informants from 4 departments of Directorate of Youth affairs were purposely selected. The study adopted descriptive survey and correlational research designs where data was collected using questionnaire and focus group discussion guide. Qualitative data was analyzed and presented in narrative statements while inferential statistics were analyzed using Pearson correlation coefficient and multiple regression analysis to test hypotheses. The research formulated a hypotheses in null state and subsequently, F-Test was used test it portraying; r (247) =.196, R2 0.38, F (5,242) = 9.777 p≤.05, implying that the levels of monitoring and evaluation practices possessed by youths may be a good predictor of performance of youth conservation projects. This inferred to the rejection of the null hypothesis and the conclusion made that H1: There is a significant relationship between monitoring and evaluation practices and performance of youth solid waste management projects in Nairobi County. The study findings provided the evidence that the level of performance increases as monitoring and evaluation practices intensifies. The researcher recommends a Policy action by government to incorporate youths to obtain and nature monitoring and evaluation skills through industrial attachments in National and County entities dealing with conservation projects; to enhance gainful youth conservation projects

Implementation Process of Project Control Systems and Performance of Rural Roads Construction Projects in Kenya: Role of Project Team Experience Diversity

Project managers have always endeavoured to effectively implement project controls systems during execution of projects to enhance rates of projects successes. However lack of understanding of the role of diversity of experiences among the workforce has hindered the ultimate performance of the project control systems in influencing the performance of construction projects. This paper sought to establish the extent to which project team experience diversity influence on the relationship between implementation process of project control systems and performance of rural roads construction projects in Kenya. The study adopted the pragmatism paradigm and the correlational survey research design. Descriptive statistics were analysed using frequencies, percentages, arithmetic mean and standard deviation while inferential statistics were analysed using Pearson’s Product Moment correlation (r), simple regression and stepwise regression (R2). Ftest was used to test the hypotheses. Tests of statistical assumptions were carried out before analysis. The results indicated that with r= 0.533, R2 = 0.284 F (1,195) = 77.208 at p=0.0000.05, the null hypothesis was failed to be rejected and therefore concluded that the significant relationship between implementation process of project control systems and performance of rural roads project does not depend on the interaction between implementation process of project control systems and project team experience diversity. It was therefore recommended that project team experience diversity among the professionals should be encouraged, communicated and shared for the common purpose of achieving high performance in projects

Assurance of marketed milk quality in Kenya

Food safety standards require the implementation of specific standards from production-to-consumption. The Hazard Analysis Critical Control Points (HACCP) is now a widely accepted methodology in risk analysis for industrially processed foods. The application of HACCP is a bigger challenge in developing countries where food market channels are less formal.. This study adapted a HACCP methodology to assess health risks at different points in the informal milk marketing network. Key critical control points identified for high total bacterial counts were channels with multiple transaction points which took considerable time from the farm without refrigeration facilities. High coliform counts were associated with the use of plastic versus metal containers. Approximately 13% of samples were adulterated with added water. Recommendations for procedures to improve milk quality and how these can be communicated to farmers, market agents and consumers are proposed and discussed

PROJECT TEAM DEMOGRAPHIC DIVERSITY AND PERFORMANCE OF RURAL ROADS CONSTRUCTION PROJECTS IN KENYA

Technology sustainability in organisations is enhanced through creativity and innovation. By so doing, organisations are able to compete in turbulent markets and risky environments. With advances of technology, demographic diversity among the workforce has quickly become the greatest engine in business growth around the world since it enriches the workplace through broadening employee perspectives, strengthening their teams, and offering greater resources for problem resolution. Today’s workforce in organisations is a mix of different demographic factors. Most studies on demographic diversities among the workforce as well as emerging technologies have continuously resulted into inconsistent results on the direction and magnitude of their influence on performance of projects. The most affected include the construction of rural infrastructure projects especially roads due the role they play in supporting creativity, innovation and technology transfer in the rural areas and importantly demographic diversity is more pronounced. This paper therefore sought to establish the influence of age, gender, ethnicity and religion diversities of workers on performance of rural roads construction projects. The study was based on Kenya Rural Roads construction projects in Kenya. This paper adopted cross-sectional correlational survey design where structured questionnaire, interview guide and focussed group discussion were used in obtaining data from workers in rural roads construction projects. Descriptive and inferential analysis carried out indicated r= 0.788, R2 = 0.783, and F (1,195) = 319.256 at level of significance p=0.000<0.05. The null hypothesis was therefore rejected and concluded that there is a significant relationship between project team demographic diversity and performance of rural roads construction projects in Kenya. These findings indicate a thoughtful need to consider demographic diversity when constituting the project team to enhance performance in rural roads construction projects. This is therefore a clear evidence for government to draft policies to reaffirm the importance of project team demographic diversity in all its projects. For organisations and business practitioners, this paper recommends that firms should establish a robust system that records, collates, analyses, evaluates and recommends the best practices on effective implementation of diversity initiatives. This study recommends further study that would identify all demographi