If the bioeconomy is really going to take off, do we need to pay more attention to the feedstocks fueling this trend?
Right now, says Hyfé cofounder Michelle Ruiz, microbial fermentation typically runs on purified sugars such as corn dextrose, which are expensive and come with a high environmental footprint.
As a result, she says, the race is on to find a cheaper and more sustainable approach, from valorizing industrial and agricultural waste streams; to extracting cellulosic sugars from non-food crops; to finding microbes that can sidestep sugars altogether and convert carbon in air into protein instead.
But one source of sugars that has not been very effectively valorized, yet, is the sugary wastewater and some solid waste from food manufacturing facilities, says Ruiz, who teamed up with LanzaTech biochemist Andrea Schoen in 2021 to form Hyfé.
Wastewater treatment
Ruiz, who used to run a wastewater treatment plant for oil giant Exxon Mobil, says food manufacturers are currently paying surcharges to treat millions of gallons of sugary wastewater every year. With some pre-treatment steps, this could be utilized to feed microbial fermentation facilities, she told AgFunderNews at the recent SynBioBeta conference in San Jose, California.
According to Ruiz: “Wet corn mills [which produce dextrose] are really water and carbon intensive. And so if you’ve looked at some of the LCAs [life cycle analyses] that are publicly available from precision fermentation companies, the carbon footprint of the feedstock can be 80% of the LCA.
“And cost is a problem too. The cheapest corn dextrose from a co-located facility can be $400 a ton, but if you’re making isoprene [via microbial fermentation], for example, and your yield is 25%, by the time that you’ve paid for your feedstock, you’ve already reached the price of isoprene [from petrochemicals].
“Now we’re really at the stage that if we want to make chemicals, foods, and materials that are cheaper than their carbon intensive incumbents, something has to be cheaper, and that’s the feedstock.
“At Hyfé, we are working with wastewater from food processors and more solid biomass waste. With the wastewater streams, we’ve developed a process that uses membrane separation to remove as much of the sugar as possible and return very, very clean water, so we save the manufacturers both on wastewater treatment costs and on clean water costs.
“In many processes that require membranes, with the flocculation steps and all the pretreatment steps that come before membranes, you end up losing a lot of your sugar. What we’ve done is created a process that doesn’t lose sugar and allows us to capture as much of that sugar at the end of the stream as possible.”
