In an attempt to divert waste from landfill, the government has increased landfill gate fees with plans to ban all organic waste to landfill within the next few years. Anaerobic digestion (AD) is a potentially effective organic waste treatment method and landfill alternative which several waste producers have begun to utilise or consider.
Treatment of waste in an anaerobic digester both accelerates the decomposition process and produces useful by-products in the form of biogas and digestate. Biogas consists of approximately 50% methane and 50% carbon dioxide and can be upgraded to compressed natural gas, which is used as an LPG replacement or combusted directly in a generator to produce electricity and heat. The digestate produced is nutrient rich and can be used as a liquid fertiliser which returns nutrients to the soil and thereby closes the loop.
Less than 20 large scale AD installations exist in South Africa, of which, far fewer are currently operating as intended. This can be attributed to several factors. AD is a biologically mediated process generally occurring at low temperature and pressure. There are several operational challenges associated with biological systems which require a constant and regulated environment specific to the needs of the microbial community in order to operate optimally. Small deviations can result in huge process upsets and can take much longer to rectify.
As result of the small biogas industry in South Africa, very few companies and people have the experience necessary to operate anaerobic digesters. Additionally, many anaerobic digesters have been installed by international companies with very poor transfer of knowledge and training taking place before project handover. As a result, many companies with new biogas installations find themselves in the position where they are unequipped to operate their new digester and are unable to call on the expertise of others in South Africa. In many cases existing designs have been installed without a full investigation into the appropriateness for the specific waste stream, resulting, in a sub-optimal process.
Subsequently, many anaerobic digesters are operated inefficiently and with many process upsets for some time before they begin costing their owner’s excessive amounts money with no sign of their promised payback ever being reached. Some companies choose to cease operation entirely.
GCX Zero Waste are one of the few companies that possess the necessary skills to assist companies with the optimal operation of their digester. With a contracted team of specialists that have more than 50 years of combined experience in the management and operation of anaerobic digesters. Furthermore, we have the waste management expertise required to effectively manage the intake of additional feedstock and the downstream handling of the digestate produced.
GCX Zero Waste has had the opportunity to showcase these skills at two AD plants. We have taken over the management and operation of the AD plant at Elgin Fruit Juices in Grabouw and are consulting on the management of a biogas digester at an agro-processing client. Both digesters have had significant operational challenges but are in the process of being rehabilitated through careful and consistent operation.
GCX Zero Waste has also been able to offer clients expertise on the handling of their waste produced during the period for which the digesters were non-operational as well as the waste produced which exceeds the digester’s capacity and cannot be digested.
We believe that AD is an undervalued and underutilised technology in South Africa which, under the proper management, plays an important role in the circular waste economy and provides significant economic benefits, which GCX Zero Waste can help businesses to realise.