| Abstrakt: |
Although waste treatment using photosynthetic bacteria provides beneficial products, the use of free cells limits product recovery and biomass recycling. This research demonstrated the recycling efficiency of Rhodopseudomonas faecalisPA2 immobilized in Ca-alginate for waste cooking oil removal and value-added product recovery and provided a strategy to improve alginate bead stability. Oil removal by immobilized bacteria increased during recycling, but the beads cracked after 3 cycles. To improve bead stability and recycling time, the used beads were immersed in 2% CaCl2for 24 h before use in each cycle to facilitate Ca2+coordination in the alginate. After 10 cycles (90 days), the treated beads showed no disintegration and removed 76.26% oil, an increase of 53.87% over single-use beads. The scanning electron microscopic images revealed no surface damage; the internal pores of the cross-section bead where bacteria resided remained unchanged, whereas the untreated bead was destroyed. Energy-dispersive X-ray analysis showed an increase in Ca2+in the treated beads, indicating Ca2+absorption during bead immersion. The recovery of value-added products after 10 treatment cycles demonstrated an increase in biomass, protein, and carotenoids by 554.05%, 68.38%, and 2,719.10%, respectively, compared to that for single-use immobilized bacteria. The proposed method to enhance alginate bead recycling, as well as photosynthetic bacteria immobilized in alginate beads, could be a viable alternative for the long-term treatment of waste cooking oil. |
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