Effect of iron and manganese on ammonium removal from micro-polluted source water by immobilized HITLi7T at 2 °C

In this study, trace metals (Fe & Mn) were applied to enhance NH4+-N removal in source water at 2 degrees C, and 22.7% of initial 2.20 mg/L NH4+-N was removed by pre-treating granular activated carbon (GAC) with Fe & Mn before immobilizing Acinetobacter harbinensis HITLi7(T) to form biological activated carbon (BAC). Biomass and dehydrogenase activity (DHA) on this modified BAC were 2.80 x 10(8) CFU/g-DW C and 0.50 mg/L/g-DW C, respectively, both the highest. Additionally, 4.76 times more biomass and 9.76 times higher DHA of HITLi7(T) were observed in the cultivation with Fe & Mn dosing. Extracellular polymeric substances (EPS) measurements found Fe & Mn dosing could increase total EPS amount (44.3% higher) and polysaccharide (PS) ratio (1.50% higher) secreted by HITLi7(T). According to the results of 3D-excitation-emission matrix (3D-EEM) fluorescence spectra and infrared spectra (FTIR) analysis, Fe and Mn promoted the secretion of tryptophan-like substances and changed functional groups C-OH, C-O-C, C=O and COOH, which are associated with protein and PS.