Plasma Gasification of Municipal and Hazardous Waste
The problems of ever increasing landfills are a global issue and a sustainable solution is required where humans do not dispose of waste by simply putting it into huge heaps. The best case scenario of dealing with waste, both for the environment and for its monetary value, is to convert it into useful products that can be sold at a profit.
The plasma waste gasification plant will render the LEIP the first zero solid-waste Eco-Industrial Park in the world. The PWGP will provide an alternative to the disposal of all hazardous solid-waste generated within the LEIP, including chemicals and metals that have been removed from process water in the various plants, thereby being one of the first eco-industrial parks to eliminating industrial hazardous waste in a safe and environmentally friendly manner.
The proposed plasma waste gasification plant (PWGP) will gasify industrial chemical hazards and municipal hazardous waste, while producing enough electricity for itself, and will produce vitrified slag that can be used as aggregate in a proposed precast concrete manufacturing plant, although it is a relatively small amount. The PWGP will initially gasify 250 tonnes of municipal type solid-waste per day, and can also gasify hazardous and radioactive waste. The Plasma Waste Gasification Process is distinctly different from incineration and the main differences between Plasma Waste Gasification Process and Waste Incineration are discussed in the table further below on this page. The PWGP will initially obtain their waste feedstock from the Musina municipal dump and from construction activities within the LEIP. Thereafter, it will also gasify the general and hazardous waste generated by industrial and other business activities occurring within the LEIP, as well as from the housing areas.
In addition, depending on the capacity and economics of the plant, the PWGP could alleviate the Vhembe district of the environmental and social burdens associated with waste disposal, the creation of landfills and the operation of incinerators. The municipal waste gasification will transform solid-waste (general and hazardous) into sufficient syngas for enough power so that both plants can sustain its own power requirements, while the additional syngas will be utilised as feedstock to the CTL plant and to the Nitrogen Complex within the LEIP.
Polyvinyl Chloride (PVC) is one of the major polluting plastics that cause great concern in South Africa. Technology for the catalytic oxidation of hydrogen chloride using oxygen was developed by Sumitomo Chemical Co. Ltd, and licensed to Bayer in 2008. The LEIP will investigate the economic viability of building a chlorine recycling plant at Musina, particularly since the cost of recycling PVC to produce pure chlorine is estimated to be about half of the actual cost of buying chlorine in the market.
The new chlorine recycling technology was awarded the prestigious Green & Sustainable Chemistry Award in Japan for being both energy-efficient and environmentally friendly. It enables a reduction in energy consumption of more than half versus the conventional process.
All waste can be gasified. Metals, Builders’ Rubble and Glass are mechanically recovered, along with Polyvinyl Chloride (PVC) plastics. Other waste is converted to Syngas.
Mechanical PVC Recycling
Mechanical recycling of source-separated PVC is technically relatively simple and common practice. Suitable post-use products are those which are easy to identify and separate from the waste stream or which can be kept relatively clean, ending up as a high-quality recycled material for use within the existing range of PVC applications. Examples are: pipes (usually recycled into pipes), window profiles (recycled into profiles or pipes), flooring, roofing membranes, coated fabrics. These flexible applications are sometimes recycled via the Vinyloop process or reprocessed into products such as mats, traffic cones. Recycled PVC materials which contain another material to fulfill their function, but cannot be separated into pure PVC (so called `composites’) is only suitable for such applications where the mixed composition can be tolerated. PVC recycling operations, covering such products, have also been initiated.
The LEIP will never incinerate PVC or any other waste, for that matter.
Illustration of plasma gasification of waste to generate syngas from which high value products are produced.