Treatment of Simulated Saline Wastewater from the Coal Chemical Industry Using Ecological Floating Beds Enhanced with Arbuscular Mycorrhiza

Abstract

For the problem that few technologies can be directly used to treat wastewater with middle and low salt, in this study, arbuscular mycorrhizal (AM) fungi were used to enhance the tolerance of wetland plants to salt stress. Ecological floating beds (EFBs) enhanced with AM fungi were constructed to explore a new technology as well as to treat wastewater with low and medium salt content, but also to overcome the low tolerance to salt stress and low salt removal by EFB plants. Results showed that canna plants (Canna indica L.) were well colonized by AM fungi (Glomus etunicatum) and the mycorrhizal colonization rate was not affected by salt stress. Inoculation with AM fungi enhanced the ability of the EFBs to treat saline wastewater. After treatment by EFB with AM for 21 d, removal rates of total dissolved solids (TDS), chemical oxygen demand (COD), total nitrogen (TN), and total phosphorus (TP) were 36.1%, 74.4%, 57.6%, and 59.1%, respectively, which were higher by 79.2%, 36.4%, 32.7%, and 37.6% over those with treatment by EFB without AM, respectively. Removal rates of Na, K, Ca, and Mg were 34.4%, 61.3%, 57.4%, and 51.9% after 21 d of treatment by EFB with AM, which were higher by 11.4%, 37.1%, 18.3%, and 24.6%, respectively, than removal rates with treatment by EFB without AM, respectively. Plant sample analysis showed that AM increased the Na uptake of plants and Na transportation from root to shoot, and this may be the reason that AM enhanced the ability of the EFBs to treat saline wastewater. This study indicated that AM fungi can be used to improve the ability of EFB to remedy water pollution and increase salt removal efficiency.