pH 对预氧化沸石滤柱启动过程中除锰效率的影响

In view of the long start-up period of the current contact oxidation manganese removal method, modified zeolite filter media coupled with sodium hypochlorite preoxidation was used to assist the start-up of the filter column. Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) were used to analyze the filter materials, the effect of raw water pH on the start-up of the filter column was investigated, and the dosage of sodium hypochlorite for continuous operation was optimized. Static adsorption experiments were conducted on modified zeolite filter media, and column start-up experiments were conducted at feed water pH of 6.5, 7.0 and 7.5, respectively. The results showed that the adsorption of Mn²⁺ by the modified zeolite filter media was in accordance with the Langmuir model and quasi-secondary kinetic equation, and the removal rate of Mn²⁺ by the modified zeolite filter media increased with increasing pH when the pH was 5.5~8.0. The manganese penetration periods of the filter columns at the three different pHs were 5, 8 and 9 days, respectively, and were successfully activated on day 20th, 16th and 14th; and the minimum doses of sodium hypochlorite were 0.8, 0.3 and 0.2 mg·L⁻¹ for the three filter columns with sodium hypochlorite preoxidation, respectively. SEM and XRD results confirmed the appearance of Birnessite on the surface of the filter media, while the EDS and XPS results showed that higher pH resulted in both higher manganese content and higher average valence on the surface of the filter media, respectively. The results of this study can provide a reference for the pH range favorable for Mn removal in surface water plants and the adsorption of Mn by zeolites during start-up process.