Ammonium nitrogen removal from coking wastewater by chemical precipitation recycle technology.
Ammonium nitrogen removal from wastewater has been of considerable concern for several decades. In the present research, we examined chemical precipitation recycle technology (CPRT) for ammonium nitrogen removal from coking wastewater. The pyrolysate resulting from magnesium ammonium phosphate (MAP) pyrogenation in sodium hydroxide (NaOH) solution was recycled for ammonium nitrogen removal from coking wastewater. The objective of this study was to investigate the conditions for MAP pyrogenation and to characterize of MAP pyrolysate for its feasibility in recycling. Furthermore, MAP pyrolysate was characterized by scanning electron microscope (FESEM), transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FTIR) as well as X-ray diffraction (XRD). The MAP pyrolysate could be produced at the optimal condition of a hydroxyl (OH(-)) to ammonium molar ratio of 2:1, a heating temperature of 110 degrees C, and a heating time of 3h. Surface characterization analysis indicated that the main component of the pyrolysate was amorphous magnesium sodium phosphate (MgNaPO(4)). The pyrolysate could be recycled as a magnesium and phosphate source at an optimum pH of 9.5. When the recycle times were increased, the ammonium nitrogen removal ratio gradually decreased if the pyrolysate was used without supplementation. When the recycle times were increased, the ammonium nitrogen removal efficiency was not decreased if the added pyrolysate was supplemented with MgCl(2).6H(2)O plus Na(2)HPO(4).12H(2)O during treatment. A high ammonium nitrogen removal ratio was obtained by using pre-formed MAP as seeding material.
Zhang
Tao
T
State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210093, Jiangsu, PR China.
Ding
Lili
L
Ren
Hongqiang
H
Xiong
Xiang
X
D011232:Chemical Precipitation; D003077:Coke; D003247:Conservation of Natural Resources / Q000379:methods; D019652:Extraction and Processing Industry; D055772:Green Chemistry Technology / Q000379:methods; D006863:Hydrogen-Ion Concentration; D017745:Incineration; D007220:Industrial Waste / Q000032:analysis*; D017616:Magnesium Compounds / Q000737:chemistry; D046529:Microscopy, Electron, Transmission; D009584:Nitrogen / Q000032:analysis* / Q000737:chemistry; D010710:Phosphates / Q000737:chemistry; D000644:Quaternary Ammonium Compounds / Q000032:analysis* / Q000737:chemistry; D012972:Sodium Hydroxide / Q000737:chemistry; D000069877:Struvite; D014865:Waste Disposal, Fluid / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000737:chemistry
D003077:Coke; D007220:Industrial Waste; D017616:Magnesium Compounds; D010710:Phosphates; D000644:Quaternary Ammonium Compounds; D014874:Water Pollutants, Chemical; D012972:Sodium Hydroxide; D000069877:Struvite; D009584:Nitrogen