活性炭催化臭氧处理畜禽养殖模拟污水氨氮的效果及机制研究

周文岩; 彭焕龙; 杨铭晖; 郑燕玲; 卢钰升; 石超宏; 李雅莹; 王丹; 刘冲; 张坤; 徐培智; 顾文杰; 解开治

活性炭催化臭氧处理畜禽养殖模拟污水氨氮的效果及机制研究

Ozone Oxidation Catalyzed by Activated Carbon to Remove Ammonia Nitrogen from Simulated Livestock and Poultry Farm Wastewater

摘要

摘要:
目的针对高浓度畜禽养殖污水氨氮去除难题，本文系统探究了粉末活性炭（powdered activated carbon, PAC）与颗粒活性炭（granular activated carbon, GAC）催化臭氧氧化技术对高浓度畜禽养殖污水中氨氮的去除效果及作用机制。
方法通过优化pH和反应时间等工艺参数，结合比表面积分析（brunauer-emmett-teller, BET）、扫描电镜（scanning electron microscopy, SEM）、能量色散光谱（energy dispersive spectroscopy, EDS）、红外光谱（fourier transform infrared spectroscopy, FTIR）及电子顺磁共振（electron paramagnetic resonance, EPR）等手段表征催化剂理化性质，并基于自由基反应机制分析，揭示了氨氮去除的关键影响因素与作用规律。
结果碱性条件（pH=10）显著促进羟基自由基（hydroxyl radical, ·OH）生成，PAC催化臭氧氧化在pH=10、投加量40 g·L⁻¹、反应84 h时，氨氮（ammonia nitrogen, NH₄⁺-N）去除率高达99.6%，总氮（total nitrogen, TN）去除率达73.6%，显著优于GAC组。表征分析结果显示，PAC较GAC有更高比表面积（238.00 m²·g⁻¹）、发达的微孔结构（孔容0.082 cm³·g⁻¹）及丰富的表面含氧官能团（O-H、C-O）。电子顺磁共振检测结果证实，PAC组自由基产量较空白组提高5倍以上且持续更久（＞60 min）。此外，反应时间延长可优化孔隙结构动态变化，增强传质与催化活性。
结论研究证实PAC通过吸附-催化协同作用提高臭氧活化效率，在处理畜禽养殖污水高浓度氨氮过程中发挥重要作用。

Abstract:
Objective Ammonia nitrogen removal from high-concentration livestock and poultry farm wastewater was studied by using powdered activated carbon (PAC) or granular activated carbon (GAC) to catalyze the ozonation process.
Method pH and reaction time in ozone oxidating the simulated wastewater with addition of PAC or GAC as catalysts were optimized. Physiochemical properties of the catalysts were compared by using the Brunauer-Emmett-Teller test (BET), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), electron paramagnetic resonance (EPR), and infrared spectroscopy (FTIR). Factors and mechanisms associated with the ammonia nitrogen eradication from wastewater were studied.
Results The formation of hydroxyl radicals ^.OH in ozonation was significantly promoted at pH 10. In 84 h, 99.6% of NH₄⁺-N and 73.6% of total nitrogen (TN) were removed from the wastewater with the addition of 40 g PAC·L⁻¹. Those were significantly more than what provided by the added GAC at the same amount. Physiochemically, PAC had greater number of active sites with the larger specific surface area of 238.00 m²·g⁻¹, higher microporous volume of 0.082 cm³·g⁻¹, and more abundant surface oxygen-containing functional groups (i.e., O-H and C-O) than GAC, resulting in efficient oxidation due to the released ·OH from the decomposed ozone. The electron paramagnetic resonance (EPR) showed the free radical production to be more than 5 times higher and last longer (i.e., ＞60 m) than control. Naturally, the extended reaction time would allow further structural change and activity of the catalyst.
Conclusion PAC, more than GAC, significantly promoted the ozonation in the wastewater treatment through adsorption-catalysis synergism.

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