A review of 3D printing techniques for bio-carrier fabrication

In order to enhance wastewater treatment efficiency, many factors need to be optimised, such as organic loading rate, hydraulic retention time and aeration. This review addresses various aspects per type of employed biocarrier. Advancements in bio-carriers technology are listed along with overviews of moving bed biofilm reactor process and additive manufacturing (AM) bio-carrier. The preferred 3D printing techniques for biocarriers' manufacturing are also being discussed and analysed in depth. Finally, recent research data on 3D printed bio-carriers are presented. These involve the fabrication characteristics of the bio-carriers (specific surface area, manufacturing material, process of manufacturing), performance details of each bio-carrier (COD removal rate, NH3 removal rate) and biofilm characteristics (biofilm thickness, biofilm formation and growth, activity and adhesive force). Key aspects such as mass transfer of nutrients and dissolved oxygen are discussed, including the bio-carrier capacity to accommodate and protect microbes.