Kinetics And Pilot Study Of Simultaneous Removal Of Ammonium And Manganese From Surface Water By Manganese Co-oxides Film

Recently,the situation of surface water pollution has become more and more serious.The catalytic oxidation method has achieved good results in the simultaneous removal of iron,manganese and ammonium pollutants from groundwater.This method is now applied to surface water treatment to investigate the adaptability of manganese co-oxides film in surface water environment.In this paper,the removal efficiency of NH₄⁺-N and Mn²⁺in surface water by manganese co-oxides film was studied.The kinetics of NH₄⁺-N and Mn²⁺at different concentrations and different filtration rates were investigated.The influencing factors of the simultaneous removal of NH₄⁺-N and Mn²⁺by the manganese co-oxides film were explored.Finally,the mechanism was explored by distinguishing the biological action and catalytic oxidation of the simultaneous removal of NH₄⁺-N and Mn²⁺by manganese co-oxide film.The main results of the paper are as follows:（1）The manganese co-oxides film can effectively remove NH₄⁺-N and Mn²⁺in the surface water.The relationships between the removal of NH₄⁺-N and Mn²⁺by the active oxide film are in accordance with the pseudo-first order kinetics.The kinetic constant k_a11 of the ammonium nitrogen was greatly influenced by the ratio of the concentration of NH₄⁺-N to the concentration of dissolved oxygen.The kinetic constant k_a22 of manganese removal was influenced by the mass transfer process.（2）The dissolved oxygen concentration was an important limitation on the oxidation of NH₄⁺-N by the active oxide film.While the removal of manganese consumes a small amount of dissolved oxygen.A higher pH was beneficial to the manganese removal by the active oxide film.The pH of the water was adjusted from 7.52 to 8.50,the removal rate of manganese increased by 24.87%,and the addition of 0.28-0.42 mg/LFe²⁺to the influent water was beneficial to the removal of ammonium by the active oxide film;the temperature ranged from 10.0°C to 19.0°C,the influent ammonium concentration was 2.00 mg/L,the effluent ammonium concentration was less than 0.50 mg/L,while the influent manganese concentration was 0.80 mg/L,the effluent manganese concentration was less than 0.10 mg/L,the removal rate of ammonium and manganese can be more than 90%.（3）The activity of manganese co-oxides film can be recovered through backwashing and ozonation in the short term under low temperature in winter,and adding NaOH to water can also improve the manganese removal ability of the active oxide film in winter.The ordering of the recovery ability was as follows:the backwashing<ozone oxidation<adding NaOH to increase the pH value of the water;The higher the pH,the more manganese was oxidized;adding NaOH to adjust the water pH to 8.75 can increase the oxidation activity of the active oxide film to manganese,at this time,the concentration of NaOH was 4.27 mg/L.（4）The increase of influent manganese concentration was beneficial to the removal of ammonium nitrogen when the influent manganese concentration ranged from 0.50 to 2.00 mg/L.The more reactive manganese oxide formed on the surface of the filter,the active oxide film had a more efficient removal of ammonium.While ammonium had an adverse effect on manganese removal,manifested in oxidation of ammonium consumes alkalinity,resulting in a decrease in the pH of the water,which reduced the manganese removal efficiency by the active oxide film.（5）The catalytic oxidation and biological action completed the process of removing ammonium by the active oxide film,the catalytic oxidation accounted for59%to 73%and biological activity accounts for 27%to 41%.While the mechanism of manganese removal by the active oxide film was only catalytic oxidation process.The proportion of oxidation increased during the process of manganese removal,the oxidation ratio increased from 11%to 67%with the increase of reaction time..