A novel non-starch based cationic polymer as flocculant for harvesting microalgae

Area of Science:

• Biopolymer Chemistry
• Biotechnology
• Environmental Science

Background:

• Locust bean gum (LBG) is a natural polysaccharide with potential applications.
• Efficient harvesting of microalgae is crucial for biofuel and bioproduct industries.
• Developing cost-effective and efficient flocculants is a key challenge in microalgae cultivation.

Purpose of the Study:

• To synthesize and characterize cationic locust bean gum biopolymer (CLBG) by modifying locust bean gum (LBG) with 2,3-epoxypropyltrimethylammonium chloride (GTMAC).
• To evaluate the flocculation efficacy of the best CLBG grade for harvesting three different indigenous green microalgae species.
• To compare the performance of CLBG as a flocculant against its natural counterpart (LBG).

Main Methods:

• Chemical modification of locust bean gum (LBG) using 2,3-epoxypropyltrimethylammonium chloride (GTMAC) to produce cationic locust bean gum biopolymer (CLBG).
• Characterization of the synthesized CLBG to determine its properties.
• Flocculation experiments using CLBG to harvest Chlorella sp. NCQ, Micractinium sp. NCS2, and Scenedesmus sp. CBIIT(ISM) at varying dosages.
• Determination of flocculation efficiency for each microalgae species.

Main Results:

• Different grades of CLBG were successfully prepared.
• The optimal CLBG dosage yielded high flocculation efficiencies: 96.68% for Chlorella sp. NCQ, 96.64% for Micractinium sp. NCS2, and 97.42% for Scenedesmus sp. CBIIT(ISM).
• CLBG proved to be a more effective flocculant than unmodified LBG for the tested microalgae.

Conclusions:

• Cationic locust bean gum biopolymer (CLBG) is an effective and efficient flocculant for harvesting green microalgae.
• The developed CLBG offers a promising alternative to conventional flocculants in microalgae cultivation and harvesting.
• This study highlights the potential of modified natural biopolymers for biotechnological applications.