Waste Valorization: Recover Value from By-Products with CO₂ and Water
By Jon Thompson, extraktLAB
Last updated: October 27, 2026
Waste valorization means turning a by-product into something you can sell or reuse. extraktLAB builds the equipment and develops the process to do that with food, agricultural and botanical waste. We work with supercritical CO₂, subcritical water, preparative chromatography and molecular encapsulation, on their own or one after another.
This work goes by the name SWaVE, Sustainable Waste Valorization Experts, together with United BioScience. extraktLAB supplies the equipment and process. United BioScience sells ingredients.
Which by-products are worth a look
Value depends on what is in the material and whether anyone will buy what you recover from it. Typical streams, with the compounds usually targeted:
- Fruit and vegetable peels, pomace and seeds. Citrus peel (essential oil and flavonoids such as hesperidin), grape and apple pomace (polyphenols), tomato and carrot waste (carotenoids).
- Grain, bran and seed by-products. Rice bran (oil and γ-oryzanol, an antioxidant complex), wheat germ (vitamin E) and oilseed cake.
- Kernels and nut by-products. Mango kernel (a fat sold as mango butter for cosmetics and confectionery), almond and hazelnut skins.
- Spent beverage and botanical material. Coffee grounds, tea, spent hops and herb trimmings.
- Seafood and algae by-products. Oils and pigments such as astaxanthin.
This is a list of places to start, not a list of results. Each one needs a test on your own material before anyone should count on a number.
Four ways to recover value from a waste stream
Each method suits a different kind of compound. Most projects use one or two of them.
| Goal | Method | Typical targets | Where to read more |
|---|---|---|---|
| Recover oils, carotenoids and aroma | Supercritical CO₂ extraction | Oils, carotenoids, tocopherols, sterols, essential oils | CO₂ extraction guide, extraction equipment |
| Recover polar compounds | Subcritical water extraction | Polyphenols, flavonoids, phenolic acids | eH2O subcritical water extractor, SWE guide |
| Purify an extract to a defined fraction | Preparative chromatography | One compound family out of a crude extract | Chromatography equipment, Pure99X |
| Turn an extract into a usable powder | Molecular encapsulation | Active-carrier powders and particles | Encapsulator page |
Supercritical CO₂ extraction
Supercritical CO₂ is carbon dioxide held above its critical point. Pressure and temperature set what it dissolves, so you can pull the oil or aroma fraction first and leave the rest. Adding ethanol as a co-solvent reaches more polar compounds, and the CO₂ is recycled in a closed loop. There is no hexane to remove from the product. See the supercritical fluids extraction guide and our E140 and E180 extractors.
Subcritical water extraction
Subcritical water is liquid water kept under pressure between 100 and 374 °C (212 and 705 °F). As it heats, its polarity drops, so one system can pick up different compounds at different temperature steps. It uses water and no organic solvent. The eH2O runs from 25 to 250 °C (77 to 482 °F) with extractor vessels from 0.001 to 2.5 L, which makes it a practical way to test a stream before you scale. Background: Dump the Solvents: Switching to Subcritical Water Extraction.
Using both on the same feedstock
Citrus peel shows why. Supercritical CO₂ takes the essential oil, which holds limonene. The peel left behind still carries flavonoids such as hesperidin, and a subcritical water step recovers those. Two products come from one waste stream, and less of the material is left over at the end.
Chromatography and encapsulation
If the buyer needs a defined fraction rather than a crude extract, preparative chromatography separates it. See Pure99X and Pure99Z. If the extract has to become a dispersible powder or a particle with a carrier, the encapsulator handles that step. Both come after extraction and are optional.
Why CO₂ and water instead of hexane and other solvents
- CO₂ or water used alone leaves no solvent residue to test for or remove from the extract.
- Closed-loop CO₂ systems cut the hazardous waste and emissions that hexane and ethanol processing create. Our article on regenerative organic processing covers this in more detail.
- A cleaner extract and a cleaner leftover biomass keep more uses open for both.
What decides whether it pays
Four questions come first:
- How much of the material do you produce each year, and how consistent is it?
- How much of the target compound does it contain?
- Who will buy the recovered product, and at what purity?
- What does disposal cost you now, and what does the by-product earn today as feed, fuel or compost?
We do not quote prices or returns on this page. A feasibility study puts real numbers on those questions for your material.
How a waste valorization feasibility study works
- Tell us about the stream. What it is, where it comes from, how much you make and what you do with it now.
- Send a sample. We agree the amount and how to ship it before you send anything.
- We test it. We run it on our equipment using the method that fits the compounds you want.
- You get a written report. It covers what we recovered and what scaling would take.
Read more on the feasibility study page, or call +1 651 600 0036.
Equipment for waste valorization
The usual starting points are the E140 and E180 CO₂ extractors, the eH2O subcritical water extractor, Pure99X chromatography and the encapsulator. The full range is on the equipment page.
Frequently asked questions
What is waste valorization?
Waste valorization is turning a by-product into something you can sell or reuse, such as an oil, a polyphenol extract or a powder. Disposal cost goes down, and the by-product becomes a second product line.
Which waste streams can extraktLAB equipment work on?
Common starting points are fruit and vegetable peels and pomace, rice bran and other grain by-products, kernels and seed cakes, spent coffee, tea and hops, and other botanical material left after a first extraction. Whether a stream is worth processing depends on how much target compound it holds and whether there is a buyer for the product. A feasibility study answers that for your material.
Do I need supercritical CO₂ or subcritical water?
It depends on what you want to recover. Supercritical CO₂ reaches oils, carotenoids, tocopherols, sterols and aroma compounds. Subcritical water reaches more polar compounds such as polyphenols and flavonoids. Some feedstocks need both, run one after the other.
What is the difference between supercritical CO₂ and subcritical water extraction?
Supercritical CO₂ is carbon dioxide held above its critical point, where it dissolves oils and other low-polarity compounds, and ethanol can be added as a co-solvent to reach more polar ones. Subcritical water is liquid water held under pressure at 100 to 374 °C (212 to 705 °F). Its polarity falls as the temperature rises, so temperature steps let you target different compounds.
Can the same sample go through more than one step?
Yes. A common plan is CO₂ first for the oil or aroma fraction, then subcritical water on the material left behind for polyphenols, then chromatography or encapsulation on the extract if it needs further purification or a different form.
What does a waste valorization feasibility study involve?
You send a representative sample and describe the stream. We test it on our equipment and send you a written report on what we recovered and what scaling it would take. Sample size and timing depend on the stream, so call or email us before you ship anything.
Do you guarantee a yield or a market price?
No. Yield depends on the feedstock, its moisture and particle size, and the target compound, so we measure it on your sample. We do not quote prices or returns on this page.
Does extraktLAB sell the finished ingredients?
No. extraktLAB sells equipment and develops the process. United BioScience sells ingredients, so contact them if you want to buy finished extracts.
Talk to us about your waste stream
Email [email protected] or call +1 651 600 0036. If you would rather buy finished ingredients than equipment, see United BioScience.