Cadmium-containing Wastewater Induced by SRB: Effect of Multiple Ions and Mineralization Process

Abstract

The effects of various general and heavy metal ions in acidic cadmium-containing wastewater on SBR desulfurization and cadmium removal under different concentrations were studied. CrO₄ ²⁻ and S²⁻ inhibited SRB mineralization, and Mg²⁺, Ca²⁺, Fe²⁺, and Fe³⁺ promoted SRB mineralization at low concentration (<50 mg/L). The inhibitory concentrations of Cu²⁺, Mn²⁺, Co²⁺, Zn²⁺, Pb²⁺, Hg²⁺, Cr³⁺, and Ni²⁺ were 10, 30, 2, 20, 25, 5, 30 mg/L, respectively. The inhibition order was Co²⁺>Hg²⁺>Cu²⁺>Ni²⁺>Zn²⁺>Pb²⁺>Mn²⁺>Cr³⁺. Furthermore, the inverted microscopy and scanning electron microscopy (SEM) were used to observe the sediment crystallization process from macroscopic and microscopic viewpoints in the optimized ion environment. The experimental results show that under the mineralization of SRB, cadmium sediment crystallization is mainly divided into the rapid growth of bacteria, crystal nucleus production, block formation, and crystallization occuration. At the same time, X-ray diffraction (XRD) and energy-dispersive spectra (EDS) have also confirmed the sediment and crystallization.

Keywords

SRB / mineralization process / cadmium / multiple ions