AM fungi enhance the function of ecological floating bed in the treatment of saline industrial wastewater.

Treatment of saline wastewater attracts more and more attention due to its negative effects on the environment in China. Although salt removal from high-saline wastewater is well done in many industry factories, few technologies are available to remove salt from low-saline wastewater (total dissolved solids, TDS < 10,000 mg/L). In this study, ecological floating bed (EFB) enhanced by arbuscular mycorrhizal fungi (AMF) Glomus etunicatum was constructed to remove salt from simulated low-saline wastewater. Results showed that AM formation in Canna indica was not affected by salt stress, and a higher mycorrhizal colonization rate was even observed under salt stress relative to the control treatment. In saline wastewater containing TDS 5000 mg/L, EFB with AM inoculation (AM-EFB) removed 15.9% of TDS, 19.9% of COD, 14.2% of TN, 22.5% of TP, and 11.6-23.0% of salt ions (Na, K, Mg, and Ca) more than EFB without AM inoculation (NM-EFB) in September, and 13.0% of TDS, 15.8% of COD, 17.5% of TN, 16.6% of TP, and 8.60-22.2% of salt ions (Na, K, Mg, and Ca) more than NM-EFB in October respectively. AMF increased plant uptake to Na and the translocation of Na from root to shoot, especially at the initial stage of the experiment. Additionally, EFB function declined when environmental temperature declined independent of AM inoculation, but the presence of AM increased EFB function in the treatment of saline wastewater relative to NM-EFB. This study provides a new strategy for the treatment of low-saline wastewater and the EFB application in a low-temperature environment.