Azzjoni Nazzjonali leader Josie Muscat has recently proposed gasification technology as a waste treatment solution for Malta and as an alternative to the Sant’ Antnin waste treatment facility currently undergoing upgrading. “Three gasification plants which turn waste into energy... would be an ideal solution to solve Malta’s waste problems,” he is quoted as saying.
WasteServ Malta Ltd said that first of all it should be noted that Sant’ Antnin is composed of three main technologies: the material treatment plant, the digestion plant and the material recovery facility (MRF). The design of this system is to treat the municipal solid waste (MSW – domestic waste) which consists mainly of three fractions: the organic waste known as the wet fraction which has low calorific value, the clean dry fraction which offers the possibility of recycling and the contaminated dry fraction which is not suitable for recycling. In Malta we have an obligation to treat the organic fraction and also to recycle the dry fractions.
To achieve this goal, Malta has embarked on a strong campaign to separate the waste at source (at home and at the industry) and direct these products for recycling. This is now possible as these waste fractions are being taken to the MRF at Sant’ Antnin for sorting and bailing to be efficiently transported for recycling. This plant was inaugurated recently.
WasteServ said the rest of the MSW shall contain a large fraction of wet organic material. The optimum way of extracting the energy from this waste stream is not by incineration/gasification/ pyrolises but by digestion. In this process, the energy is extracted from the waste by an anaerobic (without oxygen) action and methane gas is released. This gas is all used to operate electrical generators and feed the grid with the power resulting from this operation.
Should the generators not be available, the gas is treated through the RTO to avoid any methane gas released into the atmosphere. The resultant digestate is treated with oxygen for stabilisation and the solid product may be used as fertiliser or compost. Producing char from gasification shall add to the problem of inert waste we have in our country due to the excess material being produced by the construction industry.
The contaminated non-organic fractions which are present in the MSW are screened by the material treatment plant (MTP) before the digestion stage. This fraction which has a high calorific value and is not suitable for recycling is suitable for gasification/incineration. Presently this waste fraction is to be used as fuel for the incinerator at Marsa. This waste fraction, with other dry material, would make the best feed for the gasification.
It should be noted that studies conducted by WasteServ Malta Ltd showed gasification technology still at its initial stages. Gasification is scarcely used in any form across mainland Europe, including in the UK. The reason behind this is a mixture of commercial and technological unsuitability, such as it being suitable only for niche waste streams (one specific type of waste). In fact, the use of gasification technology during the London Olympics is for a specific waste-stream and not for mixed MSW as resulting from our homes. In this respect, the plant at Sant’ Antnin provides a solution for meeting all the obligations of recycling and recovery from MSW.
WasteServ believes that there are different technologies suitable for different waste streams and that in the future, when Malta extends waste management processes, there will be enough waste fractions both for digestion and some gasification, or similar technologies currently evolving in the active field of waste management may become appropriate.
At Sant’ Antnin, the decision to go for the material treatment plant, to separate any contaminants from the MSW, for the digestion plant to extract energy from the wet fraction, together with a material recovery facility for the production of recyclable products, was deemed the most appropriate for Malta’s current waste management needs.