A Novel Bio-carrier Fabricated Using 3D Printing Technique for Wastewater Treatment

Abstract

The structure of bio-carriers is one of the key operational characteristics of a biofilm reactor. The goal of this study is to develop a series of novel fullerene-type bio-carriers using the three-dimensional printing (3DP) technique. 3DP can fabricate bio-carriers with more specialized structures compared with traditional fabrication processes. In this research, three types of fullerene-type bio-carriers were fabricated using the 3DP technique and then compared with bio-carrier K3 (from AnoxKaldnes) in the areas of physicochemical properties and biofilm growth. Images acquired by 3D profiling and SEM indicated that the surface roughness of the 3DP bio-carrier was greater than that of K3. Furthermore, contact angle data indicated that the 3DP bio-carriers were more hydrophilic than K3. The biofilm on the 3DP bio-carriers exhibited higher microbial activity and stronger adhesion ability. These findings were attributed to excellent mass transfer of the substrate (and oxygen) between the vapour-liquid-solid tri-phase system and to the surface characteristics. It is concluded that the novel 3DP fullerene-type bio-carriers are ideal carriers for biofilm adherence and growth.

Figure 1. Schematic of the sequencing biofilm batch reactor containing different types of bio-carriers.

Figure 2. The 4 types of bio-carriers used in the bioreactor (photograph by Yang Dong)

.

Figure 3. Surface 3D profile imaging of 3DP bio-carriers and K3 bio-carriers using profilometry: K3

(a) and 3DP bio-carriers (b).

Figure 4. SEM photographs of the surfaces of K3

(a) and 3DP bio-carriers (b).

Figure 5. IR spectra of the K3 and 3DP bio-carriers.

Figure 6. Biomass formed on the different carriers.

Figure 7. The thickness of biofilms attached to different bio-carriers on day 25.

Figure 8. COD and NH₄-N removal in SBBR for four types of bio-carriers.