The highest costs of stripping-absorption processes for ammonia recovery are related to energy (for heating and air supply) and chemical addition (for pH adjustment). In this paper, a simplified system that used no chemicals, and a renewable source of energy for heating, was tested to recover nitrogen as ammonium sulfate from food waste digestate. pH adjustment was achieved by CO₂ stripping, and vacuum tube solar collectors were used to provide heating. The effect of different temperatures (25 °C and 45 °C) and gas to liquid ratios (1700 and 2600) on ammonia removal and recovery were assessed. Ammonia removal efficiencies higher than 91% were achieved for all evaluated experimental conditions. The solar heater showed adequate capacity to increase the temperature of the liquid digestate by 21 °C and maintain the temperature at 45 °C throughout the experiment. Tests carried out at 45 °C achieved the highest ammonia removal efficiency (98%) at the lowest evaluated G/L ratio (1700). Better absorption efficiencies could potentially have been achieved if lower inlet airflow rates and packing material had been used in the absorption column.

用于氨回收的汽提吸收工艺的最高成本与能量（用于加热和空气供应）和化学添加（用于调节pH）有关。在本文中，对一种简化的系统进行了测试，该系统不使用化学药品，而是使用可再生能源进行加热，可以从食物残渣消化物中回收硫酸铵形式的氮。通过CO ₂调节pH汽提和真空管太阳能集热器用于加热。评估了不同温度（25°C和45°C）和气液比（1700和2600）对氨去除和回收率的影响。在所有评估的实验条件下，氨去除效率均高于91％。在整个实验过程中，太阳能加热器均显示出足够的能力将消化液的温度提高21°C，并将温度保持在45°C。在45°C下进行的测试以最低的总G / L比（1700）达到了最高的氨去除效率（98％）。如果在吸收塔中使用了较低的进气流量和填充材料，则可能会获得更好的吸收效率。