| The removal efficiency of different forms of nitrogen was studied in earthworm ecofilter treating domestic wastewater, and the mechanisms were discussed. Results indicated that, the major form of total nitrogen (TN) in influent water and effluent water were existed as ammonia-nitrogen (NH+4-N) and nitrate-nitrogen (NO-3-N), respectively. NH+4-N/TN in influent water and NO-3-N/TN in effluent water were 83.88% and 76.46%, respectively, NH+4-N decreased and NO-3-N increased during the process. The average removal efficiency of TN and NH+4-N were 28.08% and 90.44%, respectively, nitrate-nitrogen accumulated massively and nitrite-nitrogen (NO-2-N) accumulated a little. It was also observed that nitrification in earthworm ecofilter was strong and the denitrification was inhibited, TN removal was not as obvious as the NH+4-N removal due to the poor denitrification environment. The overall removal of TN can be improved by increasing wet/dry ratio, modifying the structure of filter, multistage filter series, following by constructed wetland, and increasing C/N ratio of the influent water. |
