| Currently, the domestic drinking water source has been polluted by the ammonia nitrogen seriously, and it exposes a big risk to people. Biological active filter (BAF) was thought to be one of most economic and effective way to remove the ammonia nitrogen.However, under low temperatures it is difficult to play a role. So, some investigations on how to improve the BAF's performance on nitrogen removal, control the ammonia pollution in drinking water in the northern part of China and improve the drinking water quality.In this study, the Fe was loaded onto the surface of activated carbon (AC) through ultrasonic and immersion method. The (behavior and mechanism of adsorption ammonia nitrogen on AC) has been investigated thoroughly through the comparison of two experiments.One is conducted with the modified activated carbon (MAC) and another one is conducted with the unmodified activated carbon (UAC). At the same time, the modified activated carbon has also been applied as the media in the filter under low temperature condition, which is used to conduct the experiment of the natural startup of BAF and nitrogen removal. The reason why this process has been enhanced was investigated through the evaluation of startup time,amount of microorganisms, and activity of the microorganism.The Fe was loaded onto the surface of AC in the form of Fe2O3. After this kind of modification, the structure and surface properties of AC was changed-the specific surface area of macropore and mesopore decreased from 46.175 m2/g to 24.683 m2/g, the pore volume decreased from 0.064cc/g to 0.043cc/g, the average pore diameter increased from 3.742 nm to 3.808 nm and surface of AC became more rough than before. At the same time, the zero point charge of AC was increased from pHPZC=5.8 to pHPZC=8.2.The uptake of ammonia nitrogen was mainly controlled by intra-particular mass transfer.The behavior of adsorption was found to obey a pseudo-second order kinetic model. Further results indicated that the adsorption of ammonia nitrogen on activated carbons was well described by the monolayer Langmiur mode and Freundlich mode. The adsorption of ammonia nitrogen on activated carbons was spontaneous and exothermic process which is due to physisorption reaction.hrough the comparison with unmodified AC during the experiment of natural biofilm culturing and nitrogen removal, the required time for the natural startup in modified AC (96 d)is shorter than that in unmodified AC (106 d). At removal efficiency of ammonia nitrogen is>95% in both reactor after the biofilm is formed.Through the comparison between reactors with unmodified and modified AC, it can be concluded that both the amount and activity of microorganism in reactor with modified is higher than that in reactor with unmodified AC. The specific degradation rate of nitrogen removal in the reactor with modified AC is 0.114mg/L · h · nmol, while this value is just 0.090mg/L · h · nmol in the reactor with unmodified AC. It clearly shows that the microorganism in reactor with modified AC has a higher activity than the microorganism in the reactor with unmodified AC. |
PDF Full Text Request