Material extrusion-based 3D printing for the fabrication of bacteria into functional biomaterials: The case study of ammonia removal application

3D printing provides a new way of microbial immobilization technology and creates innovative designed bioactive structures containing microorganisms for remediation of environmental pollution. However, the bio-ink design remains a critical challenge due to the difficulty in creating a durable and bio-friendly material. Here, a novel dual-crosslinking PEGDA-Alginate-PVA-Nanoclay (PAPN) bio-ink containing one heterotrophic bacterium is reported for 3D printing functional biomaterial with the capabilities of ammonia removal. The results showed that PAPN 3D printed bio-scaffolds could effectively remove 96.2±1.3% ammonia within 12 hours, and the removal rate increased within repeated use owing to the growth of bacteria inside the bio-scaffolds. Preservation of the bio-scaffolds under room temperature without a culture medium for 168 hours still maintained the microbial activity for ammonia removal. It is demonstrated that visible-light-based 3D printing procedures could maintain high cell viability for the majority of bacteria, and the porous structures of 3D bio-scaffolds could allow the permeability of nutrients for the growth of bacteria. This work demonstrates the potential of the dual crosslinked PAPN 3D bio-scaffold for the production and application of immobilized functional bacteria in wastewater treatment. • 3D printed bio-scaffolds are proposed for ammonia removal in wastewater treatment. • PEGDA-Alginate-PVA-Nanoclay (PAPN) bio-ink shows high printability. • Dual crosslinking enhances mechanical properties of PAPN 3D bio-scaffold. • PAPN 3D bio-scaffolds maintain viability and stability via mild dual crosslinking. • 3D bio-scaffolds were effective and reusable for ammonia removal in water.