Fiberight has developed a circular economy solution for landfill-bound MSW without the need for further source segregation.
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It has the potential to divert up to 75% of material that is currently going into landfill at a third of the cost of an incinerator. The process is transferable and adaptable, allowing the recovery of high-value products from MSW.
The core aspect of the technology is a treatment solution for the organic fraction of the waste that uses a combination of enzyme hydrolysis and advanced anaerobic technology. Enzyme hydrolysis converts cellulose fibre to sugar, which can act as a commodity raw material for the chemical and biofuel industries. The anaerobic technology is used for the generation of transport fuel or energy from the soluble food component of the waste.
The advantage of the process is that it utilises dirty, contaminated cellulose as its feedstock; to date, Fiberight has successfully trialled inputs of MSW and paper mill sludge. The process is also expected to be able to treat other waste streams such as MRF rejects, trommel fines and refuse-derived fuel.
The process involves some initial sorting to remove textiles. The waste is then pulped to break down the MSW to a cellulose-rich biomass, and this step also allows the separation of plastic and metal components for recycling. The cellulose-rich biomass is then extensively washed to remove the last of the non-organic material and produces a cellulose concentrate which is suitable for hydrolysis. The hydrolysis process in turn produces sugars and a residual high-energy biomass.
The contaminated wash water, containing a high level of soluble organic material, is fed to a liquid phase AD reactor. This is highly efficient, with residence times measured in hours rather than days and produces virtually no digestate.
Fiberight has carried out extensive bench-scale research, including sponsoring two PhDs at Southampton University, which proves the process is viable with residual UK MSW. The company has recently been awarded an Industrial Biotechnology Catalyst grant from Innovate UK to perform a technology transfer of the process on a larger scale using MSW feedstock. This project will also allow Fiberight to test the suitability of the sugars in a number of target end markets.
In the US, based on the research carried out at Southampton, Fiberight raised sufficient investment to build an 8,000 tonnes a year pilot plant, which was commissioned in October 2012. The operational information generated by this plant is currently being used as the basis for the design of a commercial plant in Iowa. This plant will be designed to produce a combination of ethanol and compressed natural gas.
In the UK, Fiberight is planning to build a commercial plant based on the production of sugars and biomethane for grid injection.
Nick Thompson is managing director of Fiberight