Challenges of immobilized algal–bacterial consortia in wastewater treatment

Immobilized microalgae-bacteria consortia emerged as a promising next-generation wastewater treatment platform, offering synergistic pollutant removal, process stability, and reduced operational costs. By entrapping microbial communities within certain matrices, immobilization enhances biomass retention and protection from toxic shocks, enabling increased treatment rates. Immobilized consortia achieve efficient nutrients recovery, while supporting organic matter degradation and micro-contaminant minimization. Moreover, immobilization facilitates downstream valorization of biomass for high-value bioproducts by simplifying harvesting and improving biomass handling. Despite these advantages, several challenges limit broader application. Long term stability, mass-transfer constraints, mechanical durability, and system scalability under real wastewater conditions remain areas requiring deeper investigation. Emerging innovations, including hydrogel formulations, 3D-printed carriers, and improved photobioreactor designs, expand the applicability of immobilized systems, paving the way toward circular wastewater biotechnologies. This mini-review synthesizes recent progress, identifies technological barriers, and highlights future research directions to transition immobilized consortia from laboratory to reliable, industry-ready technologies supporting sustainable wastewater management.