Fermentation: promising new applications for organic waste streamsPublished: 12-11-2015
More than a third of the biomass in the food production chain is lost as waste. However, the resulting waste streams contain many valuable components such as carbohydrates. These can be upgraded into new products through fermentation. Good planning and logistics are crucial to make extraction of components viable.
Many agricultural and food industry waste streams are plant-based and contain carbohydrates such as monomeric sugars, hemicellulose and cellulose. All too often, the high-value carbohydrates (as well as minerals and proteins in the waste stream) are not fully exploited. This means recyclable substances leave the production cycle and have to be replenished from other sources.
“Too many sugars are lost in the production chain,” says Marco Siemerink, business developer at MicCell Bioservices in Doetinchem, The Netherlands. MicCell is a contract research organization specialized in microbiology and biotechnology. Most of the company’s projects are bio-based fermentation processes. In recent years, the company has seen a growing interest in upcycling waste streams. MicCell works for clients not only in The Netherlands, but also in Germany, Belgium, Italy and South America.
“Only some of the waste from organic waste streams is currently upcycled. Most of it is left unused. That’s a shame. We’re convinced it is possible to reuse more than ninety per cent of the sugars in the various waste streams using existing fermentation technology,” says Siemerink.
Easy or Difficult to Extract
MicCell has handled a wide variety of projects over the past few years. Siemerink explains: ‘We’ve worked on fermentation solutions for both relatively easily extractable sugars, from confectionery industry waste streams, and hard to extract (lignocellulose) sugars from beet tops and bell pepper stalks. Last fall we conducted a study into the feasibility of using fermentation to upcycle the cellulose waste streams from the paper and cardboard industry.”
“We carried out that study in collaboration with Dyadic and HAN University of Applied Sciences (HAN). Dyadic supplied the enzymes that can effectively release the cellulose and HAN and MicCell contributed the knowledge, technology and equipment. The end products from these fermentation processes were bioethanol, bio-oil and lysine. Lysine could be used to enrich animal feed, for example.”
This study into paper pulp fermentation showed once again that for a process to be technologically and economically feasible, the various links in the valorization chain have to be synchronized and developed in a unified manner. As Siemerink says: “Time and again, we find that planning and logistics are the bottleneck in our upcycling ideas. For instance, reusing agricultural waste streams usually means figuring out how to pool the waste stream volumes to ensure a constant, year-round supply. Pooling is essential. More and more companies are focusing on pooling: smaller SME’s, larger food producers, farmers and greenhouse growers.”
If a company turns to MicCell to ask whether fermentation of a particular organic waste stream has potential, MicCell uses a road map to assess the economic feasibility and to develop a production protocol. The road map consists of six steps: biomass analysis, pre-treatment, hydrolysis, fermentation, purification of the end product and finally, scaling up of the entire process.
“That road map is essential,” says Siemerink. “It really helps to create an overview of the whole process and to divide it into manageable chunks. That allows us to assess the feasibility of the various options. We first calculate the cost implications in a proof of principle, so that the next steps can be taken at the lowest possible cost. There’s a go/no-go moment for every step.”
Fermentation technology has been around for a long time. Until recently it was mainly an industrial process used to ferment commercially available sugars and syrups. New technologies and abilities have changed this. Siemerink concludes: “Fermentation of 2G sugars [second generation sugars, i.e. sugars with a complicated molecular structure] is on the rise. In order to convert these into a high-quality fermentation product, we need new technologies. Big strides have been made, so now there are technologies that allow us to create high-grade end products from a growing number of organic waste streams. Fermentation offers promising new applications in almost every industry, from food to detergent and from chemicals to agriculture.”