A self-isolated acid-tolerant Parachlorella kessleri with high efficiency in treating rare earth mining sewage.

Rare earth mining sewage is a significant environmental concern due to its high acidity and ammonia nitrogen levels. Finding a sustainable and cost-effective treatment method is essential. Parachlorella kessleri FM2, a green algae strain isolated in-house, has demonstrated remarkable abilities to grow and remove ammonia nitrogen (NH-N) from highly acidic rare earth wastewater without the need for alkaline additives. After optimizing conditions, P. kessleri FM2 achieved an impressive NH-N removal rate of 7.94 mg/L/d and a removal efficiency of 98.71% in a 1.5-L photobioreactor. In semi-continuous culture, the average NH-N removal rate remained high at 6.67 mg/L/d. When scaled up to continuous culture in a 5-L photobioreactor, P. kessleri FM2 maintained stability with an NH-N removal rate of 6.79 mg/L/d. Additionally, we conducted a preliminary analysis of P. kessleri FM2's acid resistance mechanism, further highlighting its potential as a candidate for treating acidic wastewater.