InBiRa – the Insect Biorefinery: From the Utilization of Organic Residues and Waste to the Manufacture of Products

Solution approach

First, the waste and residual streams from the food sector, for example overstocked food or leftovers from canteens, are processed in such a way that the insect larvae can utilize them efficiently and grow quickly. The larvae are then processed further.

The insect biomass is rich in fat and proteins and is separated into different fractions in the insect biorefinery:

• The crude fat can be converted into lubricants, fuels or cleaning agents. The particular advantage is that the crude fat has a fatty acid composition similar to that of coconut or palm kernel oil due to its high proportion of lauric acid, thus offering an alternative to tropical oils.
• The protein content of the insects is used in the production of adhesives, binders, coatings or packaging films. The residues from the processing of the insect larvae are examined for other ways of utilization - such as the extraction of chitosan or the use as fertilizer. Chitosan is a degradable biopolymer that can be used to produce protective films, for example. Among other things, it can be used to coat clothing.

The InBiRa project is investigating the feasibility of manufacturing and the marketability of various products from the refined insect larvae in close cooperation with potential user groups. In addition, the entire manufacturing process will be subjected to a comprehensive sustainability assessment and life cycle assessment.

In the project, an insect biorefinery plant complex was planned, built and commissioned on the premises of Fraunhofer IGB, which includes all the necessary process steps. In the plant, the respective process steps, starting with the production of feed for masting the larvae (farming), through the separation of the fat and protein fractions (primary refining) and their conversion to the respective chemical intermediate product (secondary refining), were carried out and evaluated on a pilot scale.

To this end, the project team defined around 20 process units and designed the process engineering for the existing material flows. The process units include technical processes as grinding, sieving, pressing, drying, microfiltration, extraction, centrifugation and evaporation as well as several chemical reactors and a bioreactor for the conversion of the fats, proteins and chitin obtained.

Waste processing, insect mast and primary refining

Initially, the waste and residual streams were processed in such a way that they could be efficiently utilized by the insect larvae. Challenges here included the seasonal variability of the organic waste bin, the unpacking of any packaged food returns, pesticide residues in fruit and vegetables from non-organic farming and discards (e.g. cutlery) from canteen waste. When preparing the feed, attention must also be paid to a balanced ratio of nutrients and water content. If there is too much water, the larvae can drown. Too much fat in the feed leads to phase formation and thus to poor and non-reproducible larval growth, and the separation of the larvae from the remaining substrate is also impaired later on.

In a specialized mast container designed for the insect biorefinery, young insect larvae were then cultivated with the processed waste and residual materials, converting them into biomass. Here it was crucial to ensure good ventilation and climate control so that the larvae had the same growth conditions throughout the mast container and that the substrate had a suitable residual moisture content for further processing at the end of the mast.

The insect larvae that have grown on the waste and residual materials were first separated from the residual substrate by sieving during primary refining. The larvae were then inactivated and dried. The subsequent pressing of the larvae initially enables coarse separation into a fat and a protein fraction. The raw fat could then be purified in further process steps and refined for further use. The protein fraction, the so-called press cake, was chemically degreased further in order to contain the purest possible protein.

In addition to the refined fat and protein fractions, several residual fractions remain from the insect biorefinery: unutilized substrate and excrement of the larvae (frass), chitin-containing larval skins and adult flies. These residual fractions can also be converted into valuable raw materials in the course of secondary refining.

Secondary refining into intermediate products for fuels, cosmetics, cleaning agents, plastics and plant fertilizers 

The project partners have each developed specific process steps for converting the three fractions from primary refining (fat, protein, residual fraction) into higher-value products, i.e. secondary refining.

The fat fraction could be converted by chemical or microbial conversion into precursor molecules for lubricants or fuels as well as biosurfactants or soaps for cleaning and personal care products. The particular advantage here is that the fat of the black soldier fly has a similar fatty acid composition to coconut or palm kernel oil due to its high lauric acid content and therefore offers a local alternative to tropical oils.

The protein fraction could be cross-linked in the future to produce composite materials for agronomy (e.g. degradable plant pots) or used as wood adhesives or coatings. Hydrolyzed protein is also used in cosmetics and personal care products.

The residual materials produced during the rearing, mast and processing of insect larvae were also utilized. The residual substrate mainly contains cellulose, insect excrement or larval exoskeleton products. While the larval exoskeleton products were investigated for isolating chitin or chitosan, the residual substrate, the so-called frass, was examined with regard digestion into biogas and the recovery of nutrients for fertilizer production. 

Marketability and holistic assessment

The InBiRa project investigated the feasibility of manufacturing various products from the refined insect larvae of the black soldier fly. Discussions on the marketability of the new technologies with various user groups revealed great interest in a large-scale insect biorefinery for the utilization of biogenic waste streams. In addition, the entire production process was subjected to a comprehensive sustainability assessment and life cycle assessment.

At the end of the three-year project, the project consortium led by Fraunhofer IGB presented the project results and the technical modules of the established biorefinery at a closing conference on October 21, 2024. Finally, the participants from research, politics and potential users from the waste sector discussed the potential of the new technology as well as the challenges with regard to regulatory framework conditions and possible solutions in a panel discussion.

Even after the official conclusion of the project, which was funded by the Baden-Württemberg Ministry of the Environment, Climate Protection and the Energy Sector with state and EU funds, research on the insect biorefinery continues in order to be able to implement the developed process steps on a large scale in waste management. 

Collaboration and access to our insect biorefinery pilot plant complex

Thanks to our approval from the regional government to use animal by-products (fish, meat) as substrate for insect larvae in insect mast, we are able to test a large number of different types of waste and residual materials on behalf of our customers or in collaboration with partners. We would be happy to examine the waste you provide to determine its potential for use by larvae, analyze the primary fractions of fat, protein, and chitin, and convert them into fatty acid esters, biosurfactants, soaps, protein hydrolysates, and chitosan. Please feel free to contact us!