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Optimising Chlorella vulgaris bioflocculation by Aspergillus Niger pellets and their application in wastewater treatment and lipid production

Summary

This research demonstrates an innovative approach to cleaning wastewater using a combination of algae and fungal pellets. The scientists optimized conditions for growing Aspergillus niger fungi as compact pellets that can efficiently trap and harvest microscopic algae cells. When these fungal-algae pellets were used to treat wastewater, they removed over 90% of harmful nutrients like ammonium and phosphate, making it a cost-effective and environmentally friendly alternative to traditional water treatment methods.

Background

Microalgae harvesting is constrained by inefficient separation methods due to low cell densities and small cell sizes. Co-culturing filamentous fungi with microalgae offers a viable, cost-effective, and environmentally friendly bioflocculation method. Fungal pellets can effectively immobilize microalgae without requiring chemical additives.

Objective

To optimize fungal pellet formation using Aspergillus niger for efficient bioflocculation of Chlorella vulgaris and to evaluate its application in wastewater treatment and nutrient removal.

Results

Optimal pellet formation occurred at 26°C, pH 4, 1×10^6-10^7 spores/L, and 10 g/L glucose, producing large pellets (5-28 mm diameter) with 100% algal flocculation efficiency within 18 hours. Stage one wastewater treatment achieved 91.88% ammonium and 91.5% phosphate removal at 107.17 cm³/L biovolume, while stage two reuse achieved 21.85% ammonium and 57.18% phosphate removal.

Conclusion

Fungal preformed pellets provide superior bioflocculation compared to spore-assisted methods, demonstrating excellent ability to harvest microalgae and remove nutrients from wastewater. Optimal biovolume balancing is critical as excessive pellet volume counterproductively increases water turbidity, emphasizing the need for careful optimization in wastewater remediation applications.
  • Published in:Microbial Cell Factories,
  • Study Type:Experimental Research,
  • Source: PMC12593925, PMID: 41199265, DOI: 10.1186/s12934-025-02849-z
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