Reducing contamination risk and increasing yields in the production of platform sugars from UK MSW

Fiberight has created a circular economy solution to generate value-added products from municipal solid waste (MSW). The process involves thermo-mechanically treating and washing the MSW to recover two main fractions: recyclables and biomass. The washing stage generates a washwater containing soluble organic matter which can be a feed for high-rate anaerobic digesters to produce biogas, a source of renewable energy. The residual solid from washing is a 'clean' biomass rich in lignocellulosic fibre that can be converted into sugars via enzyme hydrolysis: these sugars form the building blocks for a wide range of products in a waste-based industrial biorefinery. The project will test novel methods including the use of specialised additives in the MSW washing stage to improve the quality of the washed cellulose fibre and increase its sugar yield, and a new low-cost agent for pH control, to reduce the risks of contamination from food waste and nutrients affecting the downstream sugar production stage.

Fiberight Ltd has created a circular economy solution to recover materials and generate value-added products from municipal solid waste (MSW). The process involves pulping and washing the MSW to produce three main fractions: plastic and metal recyclables, a paper-rich fibre product, and a washwater rich in organic materials. The fibre is subsequently converted into sugars by enzyme hydrolysis, and these can form the building blocks for a wide range of products in a waste-based industrial biorefinery. The washwater is fed to high rate anaerobic digesters to produce biogas, a source of renewable energy, and the cleaned water from the process can potentially be fed back into the process to minimise fresh water inputs.
The current project is developing innovative methods for process enhancement and improved product yield which are suitable for use on MSW as collected at kerbside in the UK. This could potentially offer an integrated solution to separation of the energy-rich food component in our waste from the cellulose-rich fibre wastes which are now recognised as ideal targets for second generation Industrial bioenergy and biorefinery applications. The concept is to use specialised additives to the MSW washing stage to improve the quality of the washed fibre and increase its sugar yield, and to use a new low-cost agent for pH control in the hydrolysis stage. Both of these measures will contribute to minimising sugar losses. This is as a result of adventitious and undesired bacterial growth, which consumes the desired sugar product and produces an unfavourable environment for continuing efficient hydrolysis. The research will look at different additives as enhancers of the washing process and in doing this improve separation of the MSW into clean fibre and solubilised food waste.
Process improvement may also occur through enhanced and more economic pH control during the hydrolysis process. The research will test the potential for using a secondary low-cost waste material whose properties make it ideal for buffering hydrolysis at the target pH, allowing for efficient use of the enzymes. It is likely that this approach could potentially be used in a wide range of hydrolysis and fermentation processes in other related industries where lactic acid spoilage is potentially a major problem.

The project will:
- Overcome technical hurdles that could delay implementation of the Fiberight process in the UK BBSRC Reference: BB/N023854/1 Page 1 of 2
- Develop methods that can be more widely applied to first generation fermentation processes and to the wider recovery of recyclates from Material Recycling Facilities
- Help to familiarise the general public and stakeholders with the concept and benefits of a waste-based industrial biorefinery through outreach and public engagement activities