The term “mechanical-biological treatment” (MBT) covers a wide range of processes but usually includes the reception, sorting of waste, selection of secondary raw materials, and some form of biological treatment of the organic fraction of household waste. In some cases, the “dry” fraction of household waste converted into a safe fuel: RDF or SRF, while the “wet” part converted into a compost-like product.
A key advantage of MBT is that this technology could be customized to achieve several different goals. According to the EU Landfill Directive and to achieve certain disposal parameters, typical tasks of MBT plants include:
- pre-treatment of waste before disposal at the landfill;
- pre-drying of waste by forced or otherwise;
- separation of waste by mechanical sorting into different types and fractions, depending on the purpose. For example: sorting of biodegradable waste, selection of valuable secondary resources for further processing (metals, paper, plastic, glass), selection and grinding of dry non-commodity materials to obtain high-calorie fraction and production of RDF / SRF;
- preparation of landfill waste (inert material) and materials for material utilization and/or energy utilization, such as fuel derived from waste (RDF / SRF);
- preparation of biodegradable waste to obtain a compost-like product or biogas mixture;
- preparation of inert material for use as landfill cover or for landfill reclamation.
The advantage of MBT technology over conventional waste sorting lines is that this technology involves not only sorting and separation of the waste but also work with non-commodity residues.
The production of alternative fuels (RDF / SRF) derived from waste, as part of the mechanical and biological treatment will be supported where appropriate, in places close to cement plants. At the initial stage as pilot projects.
Mechanical and biological treatment of waste to obtain alternative fuels (RDF / SRF) for the cement industry reduces the amount of waste to be disposed in landfills. This directly reduces methane emissions that could occur in the case of landfilling (if the waste was landfilled, then 1 ton of waste will produce about 62 m3 of methane due to anaerobic decomposition of the biodegradable part of the waste, equivalent to 1.38 tons of CO2, which is higher than 1 ton of CO2 emitted from waste incineration). The use of RDF / SRF also reduces CO2 emissions by replacing the combustion of fossil fuels (usually coal) see table (CO2 specific emissions). The process of design, construction, and operation of mechanical and biological waste treatment plants creates jobs related to the design, construction, and operation of MBT equipment and energy use systems. MBT projects bring together engineers, construction companies, equipment suppliers, utilities, or end-users of electricity generated. Much of the money is spent in the regions on general construction and maintenance staff, helping communities reap the economic benefits of increased employment. Innovative waste management helps communities gain improved environmental protection, effective waste management, and responsible planning.
Another advantage of MBT technology is the ability to achieve a depth of waste processing of 85-90%. That is, 90% of recycled waste will not end up in landfills, but will return to the economy, and only 10% of inert material will be disposed. There is 90% incineration of valuable materials in direct burning of waste at waste incineration plants to generate heat and electricity, which does not stimulate the conservation of resources, but only enhances their use and consumption.
Recycling and composting can save up to five times more energy compared to waste-to-energy.
Direct incineration of waste, even using the latest technologies, leads to the release of toxic metals such as lead, mercury, dioxins, and furans into the air, water, and soil. After combustion, up to 30% of toxins remain in fly ash, which is eventually deposited in soil and water, plant and animal tissues and enter the human body.
Priorities of economic development of the country – economic benefits
The possibility of increasing the depth of waste processing, including the disposal of ash by cement plants, to minimize landfill and minimize the need for new landfills. Possibility to replace fossil fuels such as natural gas or coal. In some cases, additional payments made by the project sponsor to support community programs, including support for people living near waste facilities.
Priorities of ecological development of the country
The use of RDF / SRF as an alternative to fossil fuels for cement production will lead to the following environmental benefits:
- replacement of fossil fuels;
- reduction of greenhouse gas emissions;
- addressing public health problems that arise from open waste disposal and reducing environmental impact.