In the EU, the amount of municipal waste generated per person in 2019 amounted to 502 kg, down by 3 % compared with its peak of 518 kg per person in 2008. On average, a limited share (48 %) of the municipal waste generated is recycled or composted, with the rest being landfilled or incinerated. Organic materials and food waste are the largest components of the total municipal waste generated, accounting together between 30 % and 50 %.
A versatile biorefinery concept
By converting municipal solid waste into chemical feedstocks, chemical recycling processes can significantly improve recycling rates of organic waste into higher-value products compared to compost or bioenergy production. The EU-funded PERCAL project developed innovative, sustainable solutions for waste management that help implement a circular economy. The development and optimisation of a versatile biorefinery that combines hydrolysis and fermentation of raw materials in a single step represents a qualitative leap in the valorisation of municipal organic waste. PERCAL leveraged PERSEO Bioethanol®, a pre-commercial scale plant in Valencia, Spain, developed by PERSEO Biotechnology with a capacity to process 25 tonnes of organic waste a day. “Our technology replaces the use of fossil sources to produce sustainable, high-value chemicals from organic waste that are used in a broad range of everyday products. Organic waste valorisation should increase the competitiveness of the European industry and reduce pressure on the environment, helping waste streams divert from landfills and incineration,” notes Caterina Coll, CEO of PERSEO Biotechnology.
Repurposing garbage into second-generation bioproducts
PERCAL exploited the organic fraction of municipal solid waste as feedstock to develop intermediate chemical products with huge industrial interest. These intermediate chemicals include succinic acid, lactic acid and ethanol, which are all complementary to the bioethanol produced by PERSEO Biotechnology’s biorefinery system. Leveraging the project partner’s extensive experience in PERSEO Bioethanol®, researchers combined several efficient commercial enzyme cocktails that render carbohydrate hydrolysis more effective. Chemical intermediates lactic acid and succinic acid were produced from the fermentation of hydrolysates (derived from the organic fraction of municipal solid waste) by using novel electrodialysis and membrane electrolysis methods. Researchers also valorised the protein and lipid content stemming from the fermentation by-products to produce bio-based surfactants. “We used a prototype reactive distillation plant to upscale the production of ethyl lactate derived from lactic acid. This colourless liquid could find use in cleaning products and printing inks. Using suitable catalysers, we also derived renewable hot melt adhesives (lactide and polylactic acid) through the reactive extrusion of lactic acid and other co-monomers. These co-melt adhesives hold great promise for packaging applications,” explains Coll. Succinic acid could serve as a building block in polyol production. These organic compounds enable creation of flexible textile coatings based on polyurethane. PERCAL innovations reflect a consolidated biotransformation strategy for producing high-value chemicals from the organic fraction of municipal solid waste. Further progress in meeting bioprocessing challenges could someday render organic waste conversion into useful products competitive with existing processes.
PERCAL, municipal solid waste, biorefinery, lactic acid, high-value chemicals, organic fraction, fermentation, hydrolysis, bioethanol, succinic acid, biosolvents