Removal of lead from solution by the non-viable biomass of the water fern Azolla filiculoides
- Authors: Sanyahumbi, Douglas
- Date: 1999
- Subjects: Azolla , Heavy metals -- Absorption and adsorption , Lead , Water -- Purification -- Biological treatment
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3901 , http://hdl.handle.net/10962/d1003960 , Azolla , Heavy metals -- Absorption and adsorption , Lead , Water -- Purification -- Biological treatment
- Description: The removal of lead from aqueous solution and lead-acid battery manufacturing waste-water by the non-viable biomass of the water fern Azolla filiculoides was investigated in both batch and column reactors. The maximum lead uptake by the Azolla biomass at a pH value of approximately 5, was found to be 100 mg lead/g biomass from aqueous solution. Lead removal varied from 30% of the initial lead concentration at pH 1.5 to approximately 95% at pH values of 3.5 and 5.6. Lead removal from aqueous solution decreased to 30% of the initial lead concentration if the lead concentration was initially over 400 mg/l. At initial lead concentrations of less than 400 mg/l, percentage lead removal was found to be over 90% of the initial lead concentration. Lead removal remained at approximately 90% between 10°C and 50°C. Biomass concentration (4-8 mg/l) had little effect on lead removal. The presence of iron (Fe) and lead, copper (Cu) and lead or all three metal ions in solution at varying ratios to each other did not appear to have any significant effect on lead removal. Percentage lead, copper and iron removal from aqueous solution was 80-95, 45-50 and 65-75% respectively for the different multiple-metal solutions studied. No break-through points were observed for lead removal from aqueous solutions in column reactors, with initial lead concentrations of less than 100 mg/l at varying flow rates of 2, 5 and 10 ml/min. This suggested that flow rate, and therefore retention time, had little effect on percentage lead removal from aqueous solution, which was more that 95%, at low initial lead concentrations (less than 100 mg/l). At initial lead concentrations of 200 mg/l or more, an increase in flow rate, which equates to a decrease in column retention time, resulted in break-through points occurring earlier in the column run. Percentage lead removal values, from lead-acid battery efiluent in column systems, of over 95% were achieved. Desorption of approximately 30% and 40% of bound lead was achieved, with 0.5 M HNO₃ in a volume of 50 ml, from two lead-acid battery. Repeated adsorption and desorption of lead by the Azalia biomass over 10 cycles did not result in any decrease in the percentage lead removal from effluent, which strongly suggested that the Azalla biomass could be re-used a number of times without deterioration in its physical integrity, or lead removal capacity. No evidence of deterioration in the Azolla biomass's physical integrity after 10 successive adsorption and desorption procedures was observed using scanning electron microscopy. The Azolla filiculoides biomass was, therefore, found to be able to effectively remove lead from aqueous solution and lead-acid battery effluent repeatedly, with no observed reduction in it's uptake capacity or physical integrity.
- Full Text:
- Date Issued: 1999
- Authors: Sanyahumbi, Douglas
- Date: 1999
- Subjects: Azolla , Heavy metals -- Absorption and adsorption , Lead , Water -- Purification -- Biological treatment
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3901 , http://hdl.handle.net/10962/d1003960 , Azolla , Heavy metals -- Absorption and adsorption , Lead , Water -- Purification -- Biological treatment
- Description: The removal of lead from aqueous solution and lead-acid battery manufacturing waste-water by the non-viable biomass of the water fern Azolla filiculoides was investigated in both batch and column reactors. The maximum lead uptake by the Azolla biomass at a pH value of approximately 5, was found to be 100 mg lead/g biomass from aqueous solution. Lead removal varied from 30% of the initial lead concentration at pH 1.5 to approximately 95% at pH values of 3.5 and 5.6. Lead removal from aqueous solution decreased to 30% of the initial lead concentration if the lead concentration was initially over 400 mg/l. At initial lead concentrations of less than 400 mg/l, percentage lead removal was found to be over 90% of the initial lead concentration. Lead removal remained at approximately 90% between 10°C and 50°C. Biomass concentration (4-8 mg/l) had little effect on lead removal. The presence of iron (Fe) and lead, copper (Cu) and lead or all three metal ions in solution at varying ratios to each other did not appear to have any significant effect on lead removal. Percentage lead, copper and iron removal from aqueous solution was 80-95, 45-50 and 65-75% respectively for the different multiple-metal solutions studied. No break-through points were observed for lead removal from aqueous solutions in column reactors, with initial lead concentrations of less than 100 mg/l at varying flow rates of 2, 5 and 10 ml/min. This suggested that flow rate, and therefore retention time, had little effect on percentage lead removal from aqueous solution, which was more that 95%, at low initial lead concentrations (less than 100 mg/l). At initial lead concentrations of 200 mg/l or more, an increase in flow rate, which equates to a decrease in column retention time, resulted in break-through points occurring earlier in the column run. Percentage lead removal values, from lead-acid battery efiluent in column systems, of over 95% were achieved. Desorption of approximately 30% and 40% of bound lead was achieved, with 0.5 M HNO₃ in a volume of 50 ml, from two lead-acid battery. Repeated adsorption and desorption of lead by the Azalia biomass over 10 cycles did not result in any decrease in the percentage lead removal from effluent, which strongly suggested that the Azalla biomass could be re-used a number of times without deterioration in its physical integrity, or lead removal capacity. No evidence of deterioration in the Azolla biomass's physical integrity after 10 successive adsorption and desorption procedures was observed using scanning electron microscopy. The Azolla filiculoides biomass was, therefore, found to be able to effectively remove lead from aqueous solution and lead-acid battery effluent repeatedly, with no observed reduction in it's uptake capacity or physical integrity.
- Full Text:
- Date Issued: 1999
Insubordination in the workplace
- Authors: Chadd, Kevin Mark
- Date: 1999
- Subjects: Employees -- Dismissal of -- Law and legislation -- South Africa , Labor laws and legislation -- South Africa
- Language: English
- Type: Thesis , Masters , LLM
- Identifier: vital:3668 , http://hdl.handle.net/10962/d1003183 , Employees -- Dismissal of -- Law and legislation -- South Africa , Labor laws and legislation -- South Africa
- Description: This thesis traces the development of insubordination in the employment relationship. The essence of the relationship is that the employee, by contracting out his or her productive capacity, occupies a subordinate position. The primary aim is to locate and define the nature of subordination and to investigate how the breach of this position would justify dismissal as interpreted and applied by the courts. This is achieved by investigating dismissal for insubordination under the common law contract of employment, the unfair labour practice jurisdiction and the 1995 Labour Relations Act. Initially the obligation of the employee to be subordinate, an essential term of the contract of employment, is located and defined by using the tests of Control, Organisation and Dominant Impression, which theoretically indicate the true nature of insubordination. Insubordination under the common law is equated with disobedience to the lawful and reasonable instructions of the employer which were given in good faith and fell squarely within the contractual relationship. Insubordination under the unfair labour practice jurisdiction was equated with a challenge to the authority of the employer of which disobedience was a manifestation of such intention. Instructions given by the employer under the unfair labour practice jurisdiction had to be lawful, reasonable and fair. What was fair depended on the surrounding circumstances of the dismissal and a wilful and unreasonable refusal of the employee to obey the valid instructions of the employer justified dismissal Under the 1995 Labour Relations Act it is submitted that insubordination will be dealt with in essentially the same manner as under the previous jurisdiction, subject to the Act's objectives and purposes. The disobedience of the employee is to be tolerated if that employee is attempting to achieve the Act's objectives, and any dismissal as a result of the disobedience could be unfair, because the employer's conduct fiustrates the purpose of the Act. Therefore, the contractual right of the employer to expect subordination from the employee may have been whittled away to such an extent over time that it seems superficial to regard subordination as an essential term of the contract of employment.
- Full Text:
- Date Issued: 1999
- Authors: Chadd, Kevin Mark
- Date: 1999
- Subjects: Employees -- Dismissal of -- Law and legislation -- South Africa , Labor laws and legislation -- South Africa
- Language: English
- Type: Thesis , Masters , LLM
- Identifier: vital:3668 , http://hdl.handle.net/10962/d1003183 , Employees -- Dismissal of -- Law and legislation -- South Africa , Labor laws and legislation -- South Africa
- Description: This thesis traces the development of insubordination in the employment relationship. The essence of the relationship is that the employee, by contracting out his or her productive capacity, occupies a subordinate position. The primary aim is to locate and define the nature of subordination and to investigate how the breach of this position would justify dismissal as interpreted and applied by the courts. This is achieved by investigating dismissal for insubordination under the common law contract of employment, the unfair labour practice jurisdiction and the 1995 Labour Relations Act. Initially the obligation of the employee to be subordinate, an essential term of the contract of employment, is located and defined by using the tests of Control, Organisation and Dominant Impression, which theoretically indicate the true nature of insubordination. Insubordination under the common law is equated with disobedience to the lawful and reasonable instructions of the employer which were given in good faith and fell squarely within the contractual relationship. Insubordination under the unfair labour practice jurisdiction was equated with a challenge to the authority of the employer of which disobedience was a manifestation of such intention. Instructions given by the employer under the unfair labour practice jurisdiction had to be lawful, reasonable and fair. What was fair depended on the surrounding circumstances of the dismissal and a wilful and unreasonable refusal of the employee to obey the valid instructions of the employer justified dismissal Under the 1995 Labour Relations Act it is submitted that insubordination will be dealt with in essentially the same manner as under the previous jurisdiction, subject to the Act's objectives and purposes. The disobedience of the employee is to be tolerated if that employee is attempting to achieve the Act's objectives, and any dismissal as a result of the disobedience could be unfair, because the employer's conduct fiustrates the purpose of the Act. Therefore, the contractual right of the employer to expect subordination from the employee may have been whittled away to such an extent over time that it seems superficial to regard subordination as an essential term of the contract of employment.
- Full Text:
- Date Issued: 1999
An investigation into the implementation of group work, as a method of social work intervention, in health settings in South Africa
- Authors: Caires, Juliet Margarita
- Date: 1999
- Subjects: Social group work , Community health services -- South Africa , Medical care -- South Africa
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: vital:691 , http://hdl.handle.net/10962/d1006373 , Social group work , Community health services -- South Africa , Medical care -- South Africa
- Description: This research aims to discover whether social workers employed in health settings in South Africa use group work as a method of intervention with patients. It attempts to explore in which hospitals (or particular patient populations) group work is considered possible, and to discover to what extent social workers in health settings consider group work to be beneficial to patients. It also attempts to discover some of the potential difficulties experienced in initiating group work in medical settings. An effort is also made to establish, from social workers active and experienced in the field of medical social work,what place group work might have in the broader context of health services in the future. Data was obtained through the use of mailed questionnaires, which were sent to 186 health settings, across South Africa. These settings were chosen according to the following priorities: i) those known to have social workers ii) services offered (e.g. oncology, psychotherapy) iii) size of the setting iv) geographical location (both urban and rural in all nine provinces). The sample included general public and private hospitals, psychiatric hospitals (both public and private), mining hospitals and other health settings such as old age homes and facilities for the mentally retarded and for alcohol and drug rehabilitation (accompanied by a medical facility). Responses were received from 90 health settings, with 64 of these being completed questionnaires. The majority of responses came from public hospitals, and the least from the mining hospital category. Findings of this study indicate that group work is used by 50% of the health settings in South Africa. Groups are most often therapeutic or educational in nature, are run on average once a week for an hour, and are usually of open membership. Group work is not used in some health settings, most commonly due to insufficient time (on the part of the social worker). From the findings, it seems that many more social workers would like to run groups for patients than they do presently. The benefits of group work are acknowledged by the majority of this study's sample of social workers, and if solutions could be found to problems such as heavy caseloads and insufficient time, more social workers would choose to use group work than are doing so currently. Group work is considered to be a feasible method, both in the hospitals and at primary health care level. With South Africa's growing emphasis on primary health care, and the proposed inclusion (by the Department of Health) of social work services at this level, it is important that social workers find a way in which to meet the needs of patients at both levels. With group work, this may be possible.
- Full Text:
- Date Issued: 1999
- Authors: Caires, Juliet Margarita
- Date: 1999
- Subjects: Social group work , Community health services -- South Africa , Medical care -- South Africa
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: vital:691 , http://hdl.handle.net/10962/d1006373 , Social group work , Community health services -- South Africa , Medical care -- South Africa
- Description: This research aims to discover whether social workers employed in health settings in South Africa use group work as a method of intervention with patients. It attempts to explore in which hospitals (or particular patient populations) group work is considered possible, and to discover to what extent social workers in health settings consider group work to be beneficial to patients. It also attempts to discover some of the potential difficulties experienced in initiating group work in medical settings. An effort is also made to establish, from social workers active and experienced in the field of medical social work,what place group work might have in the broader context of health services in the future. Data was obtained through the use of mailed questionnaires, which were sent to 186 health settings, across South Africa. These settings were chosen according to the following priorities: i) those known to have social workers ii) services offered (e.g. oncology, psychotherapy) iii) size of the setting iv) geographical location (both urban and rural in all nine provinces). The sample included general public and private hospitals, psychiatric hospitals (both public and private), mining hospitals and other health settings such as old age homes and facilities for the mentally retarded and for alcohol and drug rehabilitation (accompanied by a medical facility). Responses were received from 90 health settings, with 64 of these being completed questionnaires. The majority of responses came from public hospitals, and the least from the mining hospital category. Findings of this study indicate that group work is used by 50% of the health settings in South Africa. Groups are most often therapeutic or educational in nature, are run on average once a week for an hour, and are usually of open membership. Group work is not used in some health settings, most commonly due to insufficient time (on the part of the social worker). From the findings, it seems that many more social workers would like to run groups for patients than they do presently. The benefits of group work are acknowledged by the majority of this study's sample of social workers, and if solutions could be found to problems such as heavy caseloads and insufficient time, more social workers would choose to use group work than are doing so currently. Group work is considered to be a feasible method, both in the hospitals and at primary health care level. With South Africa's growing emphasis on primary health care, and the proposed inclusion (by the Department of Health) of social work services at this level, it is important that social workers find a way in which to meet the needs of patients at both levels. With group work, this may be possible.
- Full Text:
- Date Issued: 1999
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