Self-flocculating Spirulina platensis CMB-02 to efficiently treat ammonia nitrogen of rare earth elements wastewater

The study aimed to evaluate the cyanobacteria Spirulina platensis CMB-02 (S. platensis CMB-02) with self-flocculation properties to treat the ammonia nitrogen of rare earth elements (REEs) wastewater. The results demonstrated that S. platensis CMB-02 could effectively remove total ammonia nitrogen (TAN) and total inorganic nitrogen within 5 days. Simultaneously, a self-flocculation efficiency of 82.59 % was achieved by microalga in 30 min after wastewater treatment. The pH, tightly bound extracellular polymeric substances (TB-EPS), and cell morphology of S. platensis CMB-02 were identified as key factors influencing its self-flocculation capabilities. Moreover, the established semi-continuous process with a 20 % renewal rate showed a stable treatment effect, representing a TAN degradation rate of 10.9 mg/(L·d). These obtained findings could conclude that the developed approach mediated with self-flocculating S. platensis CMB-02 was a promising way for REEs wastewater treatment.