Biosolids to Bioplastics!
I received a phone call, “out of the blue,” from one of my favorite biosolids salesmen. I learned that we have in the Mid-Atlantic region a biosolids product that is fertilizing a crop which yields a valuable bio-lubricant. Learning this was such an amazing coincidence. I had keyed in on Brave Blue World, which promises an “optimistic picture” of how innovations can save humanity’s water world, and I was having trouble feeling it for biosolids. I was spending way too much time trying to paint an optimistic picture for how biosolids could be beneficially deployed in ways other than for fertilizing field crops. I was looking at non-food cropping systems, say cellulosic biomass, like coppiced willows and switchgrass as feedstock to boilers, and I had been thinking cannabis (Hemp, Inc.) and flax for “special” purposes beyond heat and electricity.
Now, “out of the blue,” I had this new fact, biosolids is being used to produce a bio-lubricant! The embrace of an optimistic picture of big ideas, transformative technologies, and new paradigms for biosolids is NOT crazy.
I have been scanning widely around the region for disruptive ideas in organic waste disposal. Aries Clean Energy, with a reference facility in Tennessee, from its account at the WEF biosolids conference is ready to break out with a biosolids gasification process reportedly in Linden, NJ); in our own region, MABA member Ecoremedy is moving forward on a similar track in Pennsylvania. In late August, a front page news article reported that a Philly refiner plans $120M plant to convert food scraps to fuel for trucks and buses, at the unbelievable rate of 1,000 tons daily (though I chuckled out loud when the company’s slide deck likened its digestate to Canadian peat moss.) This is a big idea that, while not including biosolids, helps bring organics recycling to a whole new level. A mammoth digester serving institutions and stores in Philadelphia would be the commercial-sector answer to the other half of the city’s organic waste issue. The first half was addressed by the city’s embrace of residential garbage disposal back in 2016, when the Philadelphia Water Department gave a thumbs up to in-sink food grinders (Philadelphia Goes All In on Garbage Disposals) that it hopes will increase biogas production for its biosolids dryers and co-generation system.
This big digester was also the big idea at the mid-September conference of the Mid-Atlantic Bioenergy Council in Philadelphia (MABEX 2018). I checked MABEX’s on-line program and discovered this council had given a nod to biosolids (Marketing of Bloom presented by Chris Peot), surely one of our industry’s best examples of a big idea. Did MABEX have other big ideas? MABEX 2018 offered substantial presentations on wood generated energy (e.g., NYS’s Tristan Brown), on “getting-the-job-done” urban wood recovery (in Philadelphia and Baltimore), and on the complexities of federal biogas incentives (Turning Earth’s Amy Kessler). Others presentations were “bright idea” type technology overviews, such as the conceptual potential of biochar, thermal conversion and biorefineries.
Did MABEX have any disruptive and transformative case study reference facilities? A few popped up: a Virginia hospital is using switchgrass fuel (FDC Enterprises), and another start-up company has a poultry litter digester (planet found).
No new idea coming out of MABEX 2018 was for me as big as the news announcement out of San Francisco that same week. That news was of the giant ocean-going scavenger (Huge Boom Towed Out Golden Gate To Cleanup Great Pacific Trash Patch) dreamed up by a twenty-something environmentalist, and developed by a consortium of technologists and philanthropists. The issue of the ocean’s accumulation of plastic is horrifying, and this transformative approach for its remediation is extremely compelling.
We have only this past year seen a comprehensive scoping of the global plastics pollution challenge, which I believe is the biggest “water” issue. According to Production, use, and fate of all plastics ever made mankind has made 8 billion tons of plastics since its inception in 1950, half of which is discarded waste in landfills or the environment, including the oceans. And the current news stories of the harmfulness of our global plastics accumulation seem to darken the picture (Plastic-eating mosquitoes could threaten animal food chains). The bad news extends to even so banal an activity as clothes washing (More than ever, our clothes are made of plastic. Just washing them can pollute the oceans), which, by the way, is via wastewater effluent discharges and biosolids land application.
The question occurred to me, what would it take to end the madness of non-degradable plastic production from oil with the substitution with biodegradable plastic made from biomass, including biosolids? Now that is a big idea!
Hah! I am not first with the idea, and, indeed, a scientific community has built up around this notion, which is great news, and this is a potentially exciting opportunity for biosolids. I quickly learned that the goal of biodegradable plastic is way more difficult than I had guessed. This is in part because of the huge array of plastics and uses, each with different potentials for recovery; a quick overview of this is in the recent article “All the plastic you can and cannot recycle.”. It is also more difficult because, in fact, multiple goals exist for reducing environmental risks. First, the goal of replacing fossil ingredients with biomass ingredients is seen as worthy. A second goal is production of “compostable” plastics, meaning that soil-type organisms need to be able to act on the plastic. Now we have the goal of creating plastics that will degrade in the ocean environment, a wholly different set of conditions than soil or the compost pile. These goals do not necessarily intersect, as the review paper Biodegradation of bioplastics in natural environments explains.
I discovered that I was wrong to believe that biopolymers derived from biomass automatically resulted in biodegradable plastics. I had it in my head that when biosolids fermentation yielded PLA, or polylactic acid, we had a great ingredient for bioplastic. But in Degradation of Bioplastics in Soil and Their Degradation Effects on Environmental Microorganisms I learned that “poly lactic acid (PLA) was not degraded in the soil after 28 days. …similar results were obtained in the case of long-term degradation experiment (2 years).”
What kind of organic compounds can be derived from biomass and biosolids that could be made into biodegradable plastics? We are still looking for that answer. An article in Chemical & Engineering News (8/6/2018), “Technique tracks carbon as soil microbes munch plastic,” described a method for studying mechanisms of microbial decomposition of a biodegradable plastic mulch (“poly(butylene adipate-co-terephthalate)” for use in farm fields to show that it actually works. An article about a different biodegradable plasticPolyhydroxyalkanoates, challenges and opportunities makes the point that microbial PHAs “have been developed as biodegradable plastics for the past many years,” and that “the development of a super PHA production strain combined with advanced fermentation processes to produce PHA at a low cost… will allow PHA to be produced with a competitive price compared with petroleum-based plastics.” Price is a key factor in bioplastics production and deployment, and perhaps that is where a synergy with wastewater operations is possible, since wastewater and biosolids is a very low cost ingredient.
Another opportunity for bioplastics is the replacement of polyester in our clothes with FDCA. In the article Production of bio-based 2,5-furan dicarboxylate polyesters: Recent progress and critical aspects in their synthesis and thermal properties we learn that “a new class of alipharomatic polyesters that can be prepared from monomers derived straight from renewable resources like furfural and hydroxymethylfurfural (HMF).” Furfural production has been recently advanced (Furfural production from biomass–derived carbohydrates and lignocellulosic residues via heterogeneous acid catalysts) through “an efficient strategy for the co–conversion of cellulose and hemicellulose ….” Again, digestion of wastewater solids can be modified to produce furfural instead of biomethane.
On the face of it, anaerobic digesters at WRRFs could be modified as bioreactors to produce biopolymers.
But direct production of polymers from wastewater solids may not be the best approach to using biosolids for bioplastics. The holy grail for bioplastics is the conversion of wood to ingredients of bioplastics. In Lignocellulosics as sustainable resources for production of bioplastics – A review the authors write that “major interest in utilizing non-food crops, such as lignocellulosics, for production of drop-in polymers or new dedicated bioplastics” has driven “current advances [with] fractionation and purification of lignocelluloses… that may be feasible for production of bioplastics, based on wood components.”
Researchers in the Mid-Atlantic region are engaged in this kind of research. The Catalysis Center for Energy Innovation (CCEI) is a multi-institutional research center at the University of Delaware with a “mission to develop innovative heterogeneous catalytic technologies to transform lignocellulosic (non-food-based) biomass materials into fuels, chemicals, and advanced materials.” You can read of this in the CCEI in Fueling the quest for green energy. The research by R. Cesar Izaurralde at University of Maryland’s Joint Global Carbon Cycle Center “confirms the significant role that perennial species could play in developing a sustainable biofuels industry in the U.S. and elsewhere." The article of which he is co-author is exciting: Cellulosic biofuel contributions to a sustainable energy future: Choices and outcomes. Dr. Tom Richard, director of Penn State University’s Institutes of Energy and the Environment, and speaker at the MABEX 2018, explained to me that “Penn State does have several faculty working in related areas, including biopolymers from fermentation. This is an area of future opportunity, and my department is currently advertising for a professor specializing in biomanufacturing to further strengthen our program.”
I truly believe the tipping point is coming when biomass will replace oil as a primary input to plastics manufacture, and these bioplastics will be compostable, biodegradable in soil and decomposable in oceans. That day must come, and soon, as the health of Earth’s ecosystems may hinge on human’s ending its exponential growth of plastic wastes. That the more marginal soils of our region might be deployed for biomass cultivation and that these crops and soils will need nutrients and organic matter, I can see no better resource, no lower greenhouse gas source, than biosolids. Then, that day will have come when we have achieved Biosolids to Bioplastics.