Insight into recent advances in microalgae biogranulation in wastewater treatment

Abstract

Microalgae-based technology is widely utilized in wastewater treatment and resource recovery. However, the practical implementation of microalgae-based technology is hampered by the difficulty in separating microalgae from treated water due to the low density of microalgae. This review is designed to find the current status of the development and utilization of microalgae biogranulation technology for better and more cost-effective wastewater treatment. This review reveals that the current trend of research is geared toward developing microalgae-bacterial granules. Most previous works were focused on studying the effect of operating conditions to improve the efficiency of wastewater treatment using microalgae-bacterial granules. Limited studies have been directed toward optimizing operating conditions to induce the secretion of extracellular polymeric substances (EPSs), which promotes the development of denser microalgae granules with enhanced settling ability. Likewise, studies on the understanding of the EPS role and the interaction between microalgae cells in forming granules are scarce. Furthermore, the majority of current research has been on the cultivation of microalgae-bacteria granules, which limits their application only in wastewater treatment. Cultivation of microalgae granules without bacteria has greater potential because it does not require additional purification and can be used for border applications.

Highlights

• The most recent development in microalgae biogranulation research is highlighted.

• Factors affecting microalgae granule development are discussed for the first time.

• Duration to develop granules is a crucial aspect that needs further research.

• Cultivation of single-species microalgae for rapid harvesting needs more attention.

Keywords:

• Microalgal granulation
• biogranulation
• enhanced settling ability
• microalgal-bacterial granules
• wastewater treatment

Disclosure statement

The authors assert that they have no conflicting financial or personal conflicts or issues that could have influenced the work disclosed in this article.

Author contributions

Syahirah Faraheen Kabir Ahmad: Writing-Original draft preparation; Gobi Kanadasan: Revising article; Keat Teong Lee: Supervision and Validation; Vel Murugan Vadivelu: Editing article, Revising article, Supervision, and Validation.

Additional information

Funding

This research was supported by the Ministry of Higher Education Malaysia through the Fundamental Research Grant Scheme with Project Code: FRGS/1/2019/TK02/USM/02/7