Formaldehyde and urea removal in a denitrifying granular sludge blanket reactor

Water Res. 2004 Sep;38(16):3495-502. doi: 10.1016/j.watres.2004.04.055.

Abstract

Simultaneous formaldehyde biodegradation, urea hydrolysis and denitrification in anoxic batch assays and in a continuous laboratory anoxic reactor were investigated. In batch assays, the initial formaldehyde biodegradation rate was around 0.7 g CH(2)Og VSS(-1)d(-1) and independent of the urea concentration (90- 370 mg N-NH(2)CONH(2)l(-1)). Urea was completely hydrolyzed to ammonium in the presence of 430 mg l(-1) formaldehyde and complete denitrification took place in all cases (125 mg N-NO(-)(3)l(-1)). Formaldehyde removal efficiencies above 99.5% were obtained in a lab-scale denitrifying upflow sludge blanket reactor at organic loading rates between 0.37 and 2.96 kg CODm(-3)d(-1) (625-5000 mg CH(2)Ol(-1)). The urea loading rate was increased from 0.06 to 0.44 kg Nm(-3)d(-1) (100-800 mg N-NH(2)CONH(2)l(-1)) and hydrolysis to ammonium was around 77.5% at all loading rates. The denitrification process was always almost complete (100-800 mg N-NO(3)(-)l(-1)), due to the high COD/N ratio of 6.7 in the influent. A minimum value of 3.5 was found to be required for full denitrification. The composition of the biogas indicated that denitrification and methanogenesis occurred simultaneously in the same unit. A good granulation of the sludge was observed.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Biodegradation, Environmental
  • Bioreactors*
  • Disinfectants / isolation & purification*
  • Disinfectants / metabolism*
  • Formaldehyde / isolation & purification*
  • Formaldehyde / metabolism*
  • Nitrogen / isolation & purification
  • Nitrogen / metabolism
  • Urea / isolation & purification*
  • Waste Disposal, Fluid / methods
  • Water Purification / methods*

Substances

  • Disinfectants
  • Formaldehyde
  • Urea
  • Nitrogen