[Nitrogen removal in earthworm ecofilter treating domestic wastewater].
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 (NH4+ -N) and nitrate-nitrogen (NO3- -N), respectively. NH4+ -N /TN in influent water and NO3- -N /TN in effluent water were 83.88% and 76.46%, respectively, NH4+ -N decreased and NO3- -N increased during the process. The average removal efficiency of TN and NH4+ -N were 28.08% and 90.44%, respectively, nitrate-nitrogen accumulated massively and nitrite-nitrogen (NO2- -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 NH4+ -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.
Fang
Cai-xia
CX
State Key Laboratory of Pollution Control and Resource Reuse, School of Environment, Nanjing University, Nanjing 210093, China. fangcaixia0606@126.com
Luo
Xing-zhang
XZ
Guo
Fei-hong
FH
Zheng
Zheng
Z
Li
Zhe-qin
ZQ
D000818:Animals; D001673:Biodegradation, Environmental; D017753:Ecosystem; D005374:Filtration / Q000379:methods; D009584:Nitrogen / Q000302:isolation & purification*; D009835:Oligochaeta / Q000378:metabolism*; D000644:Quaternary Ammonium Compounds / Q000737:chemistry / Q000302:isolation & purification; D014865:Waste Disposal, Fluid / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000302:isolation & purification; D018508:Water Purification / Q000379:methods; D053833:Wetlands
D000644:Quaternary Ammonium Compounds; D014874:Water Pollutants, Chemical; D009584:Nitrogen