Calcium precipitation to remove fluorine in groundwater: Induced by Acinetobacter sp. H12 as a template

摘要

Calcium precipitation induced by Acinetobacter sp. H12 can simultaneously remove F- and Ca2+. Adsorption kinetics and isotherm studies showed that the defluoridation effect improved with the increase of temperature and time. The equilibrium adsorption capacity of calcium precipitation was 7.43 mg g(-1) at the initial F- concentration of 10 mg L-1. Moreover, as the pH increased, the F- adsorption capacity decreased and the Ca2+ removal rate gradually increased. The adsorption process was highly fitted to the pseudo-second-order and the Freundlich isotherm. Adsorption thermodynamics analysis demonstrated that the adsorption process was a spontaneous endothermic reaction. The activation adsorption energy was 2.81 kJ mol(-1) and the frequency coefficient was 10.88 h(-1). EEM, SEM, XPS. XRD results indicated that the defluoridation mechanism may be due to adsorption and co-precipitation. The mechanism of Ca2+ removal may be co-precipitation with F-. It is worth-mentioning that calcium precipitation overcame the problem of adding carbon sources and avoided the microbial safety risk in the effluent. Therefore, a new insight was proposed for simultaneous remediation of Ca2+ and F- from groundwater combining the biological and chemical method.