State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China.
YANGTZE Eco-Environment Engineering Research Center, National Engineering Research Center of Eco-environment Protection for Yangtze River Economic Belt, China Three Gorges Corporation, Wuhan 430010, China.
J Environ Sci (China). 2025 Mar;149:638-650. doi: 10.1016/j.jes.2024.03.010. Epub 2024 Mar 17.
High ammonia-nitrogen digestate has become a key bottleneck limiting the anaerobic digestion of organic solid waste. Vacuum ammonia stripping can simultaneously remove and recover ammonia nitrogen, which has attracted a lot of attention in recent years. To investigate the parameter effects on the efficiency and mass transfer, five combination conditions (53 °C 15 kPa, 60 °C 20 kPa, 65 °C 25 kPa, 72 °C 35 kPa, and 81 °C 50 kPa) were conducted for ammonia stripping of sludge digestate. The results showed that 80% of ammonia nitrogen was stripped in 45 min for all experimental groups, but the ammonia transfer coefficient varied under different conditions, which increased with the rising of boiling point temperature, and reached the maximum value (39.0 mm/hr) at 81 °C 50 kPa. The ammonia nitrogen removal efficiency was more than 80% for 30 min vacuum stripping after adjusting the initial pH to above 9.5, and adjustment of the initial alkalinity also affects the pH value of liquid digestate. It was found that pH and alkalinity are the key factors influencing the ammonia nitrogen dissociation and removal efficiency, while temperature and vacuum mainly affect the ammonia nitrogen mass transfer and removal velocity. In terms of the mechanism of vacuum ammonia stripping, it underwent alkalinity destruction, pH enhancement, ammonia nitrogen dissociation, and free ammonia removal. In this study, two-stage experiments of alkalinity destruction and ammonia removal were also carried out, which showed that the two-stage configuration was beneficial for ammonia removal. It provides a theoretical basis and practical technology for the vacuum ammonia stripping from liquid digestate of organic solid waste.
高氨氮消化液已成为限制有机固体废物厌氧消化的关键瓶颈。真空氨汽提可以同时去除和回收氨氮，近年来引起了广泛关注。为了研究参数对效率和传质的影响，进行了 5 种组合条件（53°C 15 kPa、60°C 20 kPa、65°C 25 kPa、72°C 35 kPa 和 81°C 50 kPa）的污泥消化液氨汽提实验。结果表明，所有实验组在 45 分钟内脱除了 80%的氨氮，但在不同条件下的氨传递系数不同，随着沸点温度的升高而增加，在 81°C 50 kPa 时达到最大值（39.0 mm/hr）。初始 pH 值调整至 9.5 以上后，真空汽提 30 分钟即可去除 80%以上的氨氮，初始碱度的调整也会影响液体消化液的 pH 值。发现 pH 值和碱度是影响氨氮离解和去除效率的关键因素，而温度和真空主要影响氨氮的传质和去除速度。就真空氨汽提的机理而言，它经历了碱度破坏、pH 值升高、氨氮离解和游离氨去除。在本研究中，还进行了碱度破坏和氨去除的两阶段实验，结果表明两阶段配置有利于氨的去除。为有机固体废物液体消化液的真空氨汽提提供了理论依据和实用技术。
