When Wastewater Becomes Environmentally Friendly Plastic

How can the chemical industry reduce its heavy dependence on fossil resources? And what to do with bio-based industrial waste, of which millions of tons are generated annually in Germany alone? At first glance, these two questions seem unrelated. But upon closer inspection, they have much more in common. This was discovered by a Hamburg-based research team. Together, Prof. Johannes Gescher, head of the Institute of Technical Microbiology, and molecular biologist Dr. Miriam Edel from TU Hamburg, along with their colleague from the University of Hamburg, Prof. Gerrit Albert Luinstra (Technical and Macromolecular Chemistry), are working on the BIOPACE project.

The goal of BIOPACE is to convert mixed residual and waste streams into valuable so-called platform chemicals through innovative biotechnological processes. These chemicals will then serve as raw materials for the chemical synthesis of bio-based polymers and thus become the foundation for a wide variety of plastic products. This creates a new value chain for previously unused waste streams. The research project is being funded by the Joachim Herz Foundation with around one million euros. 

Conventional processes mainly produce polymers from. This results in climate-damaging CO2 emissions and environmental burdens caused by plastics’ extreme durability. BIOPACE bypasses these problems as Prof. Gescher explains: “Because we ultimately produce our polymers from biomass and CO2, we remove these from the fast carbon cycle. This means we create a CO2 sink – i.e., a system that absorbs more carbon dioxide than it emits.” 

For his research, the team collaborates with a food manufacturer. The starting point is its wastewater, which contains relatively high amounts of oils, fats, and dissolved substances. The production process at BIOPACE consists of three steps, the first two of which are biological. “The waste we work with contains a wide variety of microorganisms,” says Prof. Gescher. “Nevertheless, we must process the end product of the first process so that we ultimately obtain a clean substrate for the second process. That is probably our biggest challenge. We are trying to solve it by performing the first step with organisms that function very differently from the organism catalyzing the second step.” The key lies in altering the conditions under which the processes take place. While the first step uses organisms that thrive at low pH values, the next step employs organisms in a basic environment. The task of researching and better understanding these production organisms is handled by TUHH molecular biologist Dr. Miriam Edel.

Following these two processes, BIOPACE’s third and final step is the chemical synthesis of the polymers, the specialty of Prof. Gerrit Albert Luinstra from the University of Hamburg. “With Prof. Luinstra, we want to produce polymers,” explains Prof. Gescher, “that are not yet available on the market, but whose properties resemble those of currently-based polymers.” Possible products include films or foams that can be used as insulation materials, as well as lids for containers and bottles. “The ideal scenario is that a food manufacturer could produce packaging from its own waste. This would largely close the carbon cycle within a company. Currently, there are many resource streams that companies do not utilize.” 

Within TUHH, further collaborations on the BIOPACE project across additional departments are conceivable. For example, regarding economic feasibility calculations or automation issues. “In this context, the Collaborative Research Centre SMART Reactors is especially interesting for us,” says Prof. Gescher. “Because in the long term, we want the processes we are developing to operate autonomously and be self-regulating.” And of course, BIOPACE specifically contributes to the strategic focus TUHH has set as a whole: Engineering to Face Climate Change.