W Strydom

Biological sulphate removal in an upflow packed bed reactor

Abstract Mine waters and industrial effluents with high sulphate concentrations create a disposal problem in terms of excess mineralization of surface waters. Removal of sulphate can be achieved by various processes including biological techniques, all of which involve appreciable costs. The purpose of this investigation was to improve on known biological methods for the removal of sulphate. Good sulphate removal was obtained by providing anaerobic conditions on a solid medium and maintaining a low hydrogen sulphide concentration by recirculating the water through a photosynthetic reactor for sulphur production.

Biological sulphate removal from industrial effluent in an upflow packed bed reactor

Abstract A biological process for the removal of sulphate, using molasses as organic carbon source, is described. Sulphate is converted to sulphur via sulphide, and molasses to bicarbonate. Sulphate reducing bacteria are responsible for the reduction of sulphate to sulphide, while photosynthetic sulphur bacteria oxidize sulphide to elemental sulphur. It has been shown that these bacteria can live symbiotically in an upflow anaerobic packed bed reactor. The process is accompanied by the precipitation of calcium carbonate and heavy metal sulphides. Sulphate reduction follows zero order kinetics with respect to both reactants and products. The reduction of 1 g sulphate consumes 1.2 ml molasses and requires 6 h for completion. The optimum temperature for sulphate reduction was found to be 31°C.

The Role of Communication in Governance: The River Health Programme as a Case Study

Within South Africa, active public participation in decision-making processes and policy development is a requirement for governance to be successful. Similarly, ecosystem governance requires active public participation in environmental issues. For the public to become progressively more involved in decision-making, an increase in public understanding of, active involvement in and engagement with science, is needed. This emphasises the importance of sound science communication strategies that will lead to informed responses to environmental issues.

Co-operatives as a development mechanism to support job creation and sustainable waste management in South Africa

South Africa, as with most African countries, is facing the reality of limited economic growth, high levels of poverty and increasing unemployment. At the same time, waste generation is growing, especially in urban centres across Africa, posing a great sustainability challenge. However, the waste sector can provide significant opportunities for improving livelihoods, generating jobs and developing enterprises, through the recovery of valuable recyclables. Co-operatives are recognised as a means of formalising the large number of informal waste pickers in developing countries. This paper attempts to identify the challenges facing waste and recycling co-operatives in South Africa. Results suggest that such co-operatives still face numerous challenges relating to infrastructure, operations, and capability. They still operate largely on the fringe of municipal solid waste management, and have not been integrated effectively into such formal collection systems, making it difficult for them to access sufficiently high volumes of recyclables. In addition, some co-operatives are operating as traditional businesses (e.g. following Pty Ltd business models) with the five co-operative members (minimum required membership for registering a co-operative) taking on management roles and instead employing staff to undertake the collection and sorting of recyclables. This is sometimes done through written contracts, but often it is through verbal contracts or no formal contracts at all. Many co-operatives appear to be opportunistic in their registration, targeting short-term co-operative grants and responding to procurement policies that support co-operative development, rather than aiming for long-term sustainability. With a reported 91.8% failure rate of waste recycling co-operatives in South Africa, and the return of many co-operative members back into the informal sector, this business model is not currently creating sustainable businesses or jobs. The results highlight three criteria which are considered crucial to creating a viable co-operative movement in the solid waste management sector in South Africa; access to materials, access to markets, and business development support.