Study on two-stage air-recirculation ammonia stripping process for membrane concentrate in livestock and poultry breeding

Aiming at the problems of the subsequent treatment of the biogas liquid membrane concentrate and the large alkali consumption of the traditional stripping process, a two-stage closed-cycle ammonia stripping process was designed, and the two-stage air-recirculation ammonia stripping process was used to treat the biogas liquid membrane concentrate. Studies have shown that in the first stage of ammonia stripping, when the gas-liquid ratio is 3600, the pH of the membrane concentrate liquid after the closed loop treatment reaches the maximum value of 8.75, and the alkalinity is also reduced from the initial 8150 to 6615.After the primary stripping is completed, the pH of the membrane concentrate can be quickly increased by adding alkali to meet the normal ammonia stripping conditions for the secondary stripping tower. When the liquid ratio of the secondary stripping tower is 3600, the temperature is 40°C, and the CaO dosage is 25g/L, the removal rate of ammonia nitrogen is 86%. Adding a first-stage tower blowing off, the CaO dosage is reduced by 5g/L.