This thesis presents work relating to the synthesis, structure and stability of various arsenate phases having potential to immobilise high concentration arsenic wastes. Such wastes arise from mining and hydrometallurgy operations and the high arsenic concentrations, arising in tailings dams for example, represent an environmental concern. Large quantities of highly contaminated waste sludge are also generated by the co-precipitations of arsenic on ferric hydroxide floccs from low arsenic concentration waste streams. The disposal of this waste is becoming a prominent issue when cleaning minesite run off and drinking water. It is important therefore to consider the environmental impact of discarded arsenic residues and this project addresses the potential for its immobilisation in low stability minerals capable of return to mine sites. Two groups of phases with the potential for immobilisation of arsenic and other toxic metals are studied in this thesis. The first group are zinc arsenate zeolite analogues. These open framework structures also present the possibility of immobilization of other waste materials by ion exchange. The second group are a series of cadmium arsenate phases, which offer the potential for cadmium and arsenic immobilisation. This thesis examines the crystal structure, and synthesis of both groups of phases and examines their solubility and stability thus assessing their potential as waste immobilisation tools. The results of these studies has shown that although it is possible to make phases which are entirely composed of waste metals these phases are not stable enough for direct use in waste immobilisation processes. The crystal structures of several previously unpublished phases have been determined and a solubility product has been calculated for one of the phases.

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The City of Johannesburg is facing the simultaneous challenges of an increased generation of solid waste in the City, unemployment and the running out of land to dispose the waste. Of the solid waste that is generated, 50% is recyclable while only 10% is recycled (SOER, 2003: 69). Solid waste recycling is mainly performed through private sector initiatives in the City of Johannesburg. Consequently, there is no proper coordination with government initiatives. In order for South Africa to increase and sustain economic growth that would decrease unemployment, there should be a culture of entrepreneurship (Mass, G & Herrington M, 2006:7). Solid waste buy-back centres assist in addressing the challenges of dealing with the increased generation of solid waste and the scarcity of land for disposal. These centres also reduce the challenges of unemployment through promoting entrepreneurs to operate solid waste recycling businesses. Developed economies have managed to increase the rate of solid waste recycling to 60%. The problems associated with solid waste have been reduced by promoting recycling through a combination of legislation and setting-up of agencies to deal with solid waste recycling. South Africa has legislation and stated programmes to deal with solid waste recycling. Nevertheless, there has been complexity with implementing recycling. This is the result of a lack of co-ordination between the role-players involved in the value chain of solid waste recycling. In order for the City of Johannesburg to increase the recycling of solid waste from 10% to optimal rates of between 50% and 60%, there should be co-ordination of programmes amongst all the role players. In addition, there should also be skills provision to existing and potential entrepreneurs operating the solid waste buy-back centres. All spheres of government should promote solid waste recycling business to potential entrepreneurs and the public in order to recycle 40% of the recyclable solid waste that is not being recycled. The establishment of a solid waste buy-back centre in the City of Johannesburg is economically viable with some buy-back centre realising a net-profit of least R5 000 and some more than R30 000 per month. In order for the solid waste buy-back centre to realise a net-profit of more than R30 000 per month, there must be more than 40 tons of recyclable solid waste received by the buy-back centre per month. This study has indicated that solid waste buy-back centres rely on the economies of scale. This means that the more recyclable solid waste is received and sold by the solid waste buy-back centres, the more profitable it becomes. / Thesis (M.B.A.)--North-West University, Vaal Triangle Campus, 2009.

The City of Johannesburg is facing the simultaneous challenges of an increased generation of solid waste in the City, unemployment and the running out of land to dispose the waste. Of the solid waste that is generated, 50% is recyclable while only 10% is recycled (SOER, 2003: 69). Solid waste recycling is mainly performed through private sector initiatives in the City of Johannesburg. Consequently, there is no proper coordination with government initiatives. In order for South Africa to increase and sustain economic growth that would decrease unemployment, there should be a culture of entrepreneurship (Mass, G & Herrington M, 2006:7). Solid waste buy-back centres assist in addressing the challenges of dealing with the increased generation of solid waste and the scarcity of land for disposal. These centres also reduce the challenges of unemployment through promoting entrepreneurs to operate solid waste recycling businesses. Developed economies have managed to increase the rate of solid waste recycling to 60%. The problems associated with solid waste have been reduced by promoting recycling through a combination of legislation and setting-up of agencies to deal with solid waste recycling. South Africa has legislation and stated programmes to deal with solid waste recycling. Nevertheless, there has been complexity with implementing recycling. This is the result of a lack of co-ordination between the role-players involved in the value chain of solid waste recycling. In order for the City of Johannesburg to increase the recycling of solid waste from 10% to optimal rates of between 50% and 60%, there should be co-ordination of programmes amongst all the role players. In addition, there should also be skills provision to existing and potential entrepreneurs operating the solid waste buy-back centres. All spheres of government should promote solid waste recycling business to potential entrepreneurs and the public in order to recycle 40% of the recyclable solid waste that is not being recycled. The establishment of a solid waste buy-back centre in the City of Johannesburg is economically viable with some buy-back centre realising a net-profit of least R5 000 and some more than R30 000 per month. In order for the solid waste buy-back centre to realise a net-profit of more than R30 000 per month, there must be more than 40 tons of recyclable solid waste received by the buy-back centre per month. This study has indicated that solid waste buy-back centres rely on the economies of scale. This means that the more recyclable solid waste is received and sold by the solid waste buy-back centres, the more profitable it becomes. / Thesis (M.B.A.)--North-West University, Vaal Triangle Campus, 2009.

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Solid waste management in low income developing countries is generally the responsibility of the official sector, such as municipal corporations. However, there are extensive inputs from the from the private informal sector in waste collection, separation and recycling. Four different activities in the private informal sector have been studied to identify the potential of their integration with the official system. Where integration means that the official sector accepts those practices and incorporates them into existing practices and future plans. All the cases have been selected from the city of Karachi, Pakistan. A multiple case study approach was adopted to assess the potential for integration, constraints to integration, attitudes, relationships and dependencies. It has been concluded that under the present circumstances, the private informal activities in solid waste management cannot be integrated formally with the official system. The main constraints to integration are public and municipal attitudes, the interrelationships and dependencies, interference by politicians and the lack of understanding on the wide range benefits of integration. Future models must be developed on the private informal practices within the official systems, such as primary collection of waste through municipal sweepers. A number of benefits of the private informal practices were also highlighted by the research which may be considered as opportunities once integration takes place. The recommendations include a number of actions and potential policy changes which could be done to promote integration and a better partnership between the private informal and the public sector.