Treatment of Swine Feces by Modified Aerated Lagoon Process for Denitrification

Abstract

Investigation was carried out to improve nitrogen removal efficiency in the treatment of swine feces by the aerated lagoon process. The modified aerated lagoon process of semi-batch style for denitrification (trial) was compared with the aerated lagoon process performed in a completely aerobic condition (control).The trial process was conducted under the following conditions: Inflow time of 3 hours, gentle stirring for denitrification for 5 hours, aeration for 17 hours and settling for 2 hours.The control process was performed under the following conditions: Inflow time of the 3 hours, aeration for22hours and settling for2hours. The detention time was5days in both processes. The experimental period was 20 days. The following results were obtained.
1) There was no significant difference in effluent TOC between the two processes.T-N and NO^-₃-N in the effluent, however, were significantly (p<0.01) less in the trial than in the control process.
2) To obtain a satisfactory nitrogen removal efficiency, the acclimation for more than 8 days was necessary before application of the trial process.
3) When the TOC/T-N ratio exceeded 3, nitrogen removal efficiency rangedfrom 85 to 96%.
In conclusion, the modified aerated lagoon process of semi-batch style for denitrification made it possible to performed BOD reduction, nitrification, denitrification and settling in only one reactor for one day.