Municipal Solid Waste & RDF

Waste in this instance defines any combustible, non-hazardous material resulting from the output of household and industrial processes. This represents a wide range of feedstocks, from construction waste to biosolids from sewage. The compounds and substances present in MSW cover a large proportion of the periodic table; and different technologies may be more or less appropriate for efficient conversion. DP offers several types of combustion and gasification technology in order to provide the best solution.

Type of Municipal Solid Waste & RDF

Municipal Solid Waste (MSW) is typically the domestic types of waste from residential homes, institutions, small businesses and the like. As such, it can consist of organic (biodegradable) and non-biodegradable materials. It is typically known as ‘non-hazardous’ waste although there are categories within this which have specific hazardous characteristics. Some of the waste may also be recyclable. It differs from ‘hazardous’ industrial wastes and other toxic categories.
The term ‘refuse derived fuel’ (RDF) is generally used to define unspecified waste after basic processing to increase the calorific value (CV) of municipal solid waste (MSW), commercial or industrial waste materials.
RDF is a form of MSW that has been sorted and subject to basic processing treatment. MSW is treated by shredding and dehydrating to produce Refuse Derived fuel (RDF) or Solid/Specified Recovered Fuel (SRF). RDF consists largely of combustible components of municipal waste (non-hazardous) such as plastics and biodegradable waste and as such, has more consistent combustion characteristics than unsorted MSW.
SRF or ‘solid recovered fuel’ is waste derived fuel that meet a tighter quality specification. Combustion and handling of more homogeneous processed fuels RDF and SRF are somewhat easier than unsorted MSW.
Different types of incineration are available for MSW and RDF fuel types. Incineration of MSW is a mature technology for producing energy in many countries but the proper handling, combustion and control of emissions is critical to ensure environmental credentials. In many emerging economies, MSW is left untreated and disposed of through landfills or is subject to improper incineration, with unsustainable and environmentally damaging implications.
The increase in RDF production and availability is growing in importance as a feedstock and has implications for the long term investment decisions being made for waste to energy conversion.

Typical characteristics

There is significant variety in MSW characteristics depending on geographical location, season, and many other factors. Unsorted MSW will contain many varying materials of different composition, particle size; combustibility and moisture content. It is the more typical type of fuel to be found in emerging countries.
RDF and SRF fuels are becoming more prevalent as a feedstock and production is maturing. RDF/SRF composition is subject to categorization, but the categorisations are not globally consistent or universally applied.
The chemical properties of MSW and RDF are very important in evaluating the alternative processing and recovery options and are measured in the following dimensions: proximate analysis, fusing point of ash, ultimate analysis (major elements), energy content.

Implications

The variety in municipal solid waste (MSW) composition and differences in thermal degradation behaviour of MSW components makes the modelling, design and operation of thermal conversion systems a task that requires expertise and experience. The formation and composition of the fly ash and emissions are also a direct result of the input feedstock and must be properly understood to determine the correct process for conversion.
The technology options for energy conversion include both mass burn combustion and gasification. Each has merits depending on the nature of the fuel, the emissions requirement and the volume of fuel. DP experts are able to determine the most efficient, economically viable method of conversion from DP’s portfolio of technologies.

Municipal Solid Waste & RDF