A novel approach of using zeolite for ammonium toxicity mitigation and value-added Spirulina cultivation in wastewater

Owning to the ammonium toxicity, some ammonium-rich wastewater may not be used for algae cultivation. To overcome this problem, herein, a novel approach of using zeolite to mitigate ammonium toxicity in wastewater for value-added Spirulina production was proposed. Synthetic zeolite was used as medium for ammonium adsorption in wastewater and subsequently as slow-releaser providing nitrogen to Spirulina growth. The optimal conditions for ammonium adsorption include pH value of 8.0, zeolite dose of 300 g/L, and adsorption time of 9 h. The results showed that in terms of biomass production and ammonium recovery, zeolite-based pretreatment has great advantages over some conventional pretreatment technologies. After algae-assisted desorption treatment, ammonium adsorption capacity of zeolite increased back to 1.21 mg/g. In a real-world application, this work will provide a feasible and sustainable approach to remediate ammonium-rich wastewater, produce value-added Spirulina biomass, and recycle used zeolite, further promoting the industrialization of algae-based wastewater remediation.