The role of biodegradable particulate and colloidal organic compounds in biological nutrient removal activated sludge systems|
Drewnowski, J. & Makinia, J.
The efficiency of denitrification and enhanced
biological phosphorus removal in biological nutrient
removal activated sludge systems is strongly dependent on
the availability of appropriate carbon sources. Due to high
costs of commercial compounds (such as methanol, ethanol,
acetic acid, etc.) and acclimation periods (usually)
required, the effective use of internal substrates is preferred.
The aim of this study was to determine the effects of
slowly biodegradable compounds (particulate and colloidal),
as internal carbon sources, on denitrification, phosphate
release/uptake and oxygen utilization for a full-scale
process mixed liquor from two large wastewater treatment
plants located in northern Poland. Since it is difficult to
distinguish the effect of slowly biodegradable substrate in a
direct way, a novel procedure was developed and implemented.
Four types of one- and two-phase laboratory batch
experiments were carried out in two parallel reactors with
the settled wastewater without pre-treatment (reactor 1)
and pre-treated with coagulation–flocculation (reactor 2).
The removal of colloidal and particulate fractions resulted
in the reduced process rates (except for phosphate release).
The average reductions ranged from 13 % for the oxygen
utilization rate during the second phase of a two-phase
experiment (anaerobic/aerobic), up to 35 % for the nitrate
utilization rate (NUR) during the second phase of a conventional
Activated sludge; Denitrification; Biological phosphorus removal; Internal carbon source; Nitrogen