A novel cadmium-containing wastewater treatment method: Bio-immobilization by microalgae cell and their mechanism.

•Microalgae cells were utilized as the bioreactors to immobilize and recycle Cd ions.•The biofabrication method of CdSe QDs is facile and eco-friendly.•Possible formation mechanism of CdSe QDs in algal cells was speculated.•An effective fluorescent nanoprobe for Hg2+ detection was established.