Production of sustainable food in aquacultures without microplastics

By Petra Wiesmayer

Around 30 million tons of microplastics end up in wastewater every year, most of which ends up in the sea. In addition, plastic waste in the world’s oceans breaks down into tiny particles that are ingested by marine animals. Via the marine animals that we eat, these microplastics eventually enter our food chain. This problem exists not only in the oceans but also in freshwater – and this is precisely where the new BioBioCarrier research project at Hof University of Applied Sciences comes in.

“In pond farming or in large aquacultures, microplastics can generally be eliminated much more easily because the water systems are closed,” explains the project leader, Prof. Manuela Wimmer. “But on the other hand, here, too, the human factor means that microplastics or macroplastics still enter ponds or flow-through systems and from there find their way into the organisms of fish, food crops or shellfish. This risk is further amplified by various functional plastic components in the system itself.” For this reason, the scientists now want to develop a solution at least for closed aquacultures among other things in the field of aquaponics (the mixed culture of fish farming and soil-free crop cultivation).

Biodegradable bioplastics for aquacultures

The research focus of the BioBioCarrier project is the production of biodegradable aquaculture growth media made of biopolymers for biological water treatment entirely without microplastics, explains Dr. Harvey Harbach, a research associate in the project. “These very closely resemble curlers and provide a habitat for beneficial bacteria in a filter.” These bacteria are used to treat the aquaculture water, cleaning it of harmful substances, he said. “They convert ammonium and nitrite into the less harmful nitrate, which acts as a plant fertilizer. The problem so far is that these growth media are still made of conventional, petroleum-based plastic.”

In addition to avoiding plastic particles that are harmful to live organisms, there is another positive effect of the slow decomposition of biodegradable growth media, emphasizes Prof. Wimmer. “When the growth media decompose, they continuously release essential plant nutrients required by the cultivated crops for growth into the water as part of the decomposition process. This, therefore, results in automatic fertilization. As a result, the amount of fertilizer that needs to be added manually is reduced to zero or diminished significantly.”

Cooperation between institutes

BioBioCarrier is the first cross-institute project at the Hof University of Applied Sciences. “In this project, the Institute for Applied Biopolymer Research (ibp) and the Institute for Water and Energy Management (iwe) will further develop this future-oriented technology in an interdisciplinary and cross-disciplinary manner,” says university president Prof. Jürgen Lehmann. “The replacement of petroleum-based plastic with bioplastics is an ideal fit for sustainable and resource-saving food production with aquaponics. This further strengthens the profile of the Hof University of Applied Sciences as a green tech university.”