TY - JOUR
T1 - Nitrification at high ammonia loading rates in an activated sludge unit
AU - Campos, J. L.
AU - Garrido-Fernández, J. M.
AU - Méndez, R.
AU - Lema, J. M.
PY - 1999/5
Y1 - 1999/5
N2 - Effective nitrification of ammonia at high nitrogen loading rates, up to 7.5 kg N-NH4+ m-3 d-1 was obtained in a nitrifying activated sludge unit working at a hydraulic retention time of 1.3 h and 20°C. Bicarbonate, used as a carbon source for autotrophic microorganisms, allowed maintainance of a system very stable against different shocks due to point deficiencies of oxygen or other accidents. Ammonia conversion to nitrate was normally between 97 and 99.9%. Temporary accumulations of nitrite were quickly transformed into nitrate. The relative low specific conversion rate of the biomass in the reactor (0.5-0.7 g-N-NH4+ g-VSS-1 d-1 was compensated by the capacity of the unit to retain high concentrations of biomass (up to 15 g-VSS l-1) due to the excellent characteristics of the biomass (Sludge Volume Index of 12 ml g-VSS-1; Zone Settling Velocity of 9 m h-1. Present results show that activated sludge units can be operated efficiently as a high-rate nitrifying technology. This well-known, robust and easy to operate technology is a clear alternative to the airlift or fluidised-bed systems, which can be applied for the nitrification of high load wastewater at full scale.
AB - Effective nitrification of ammonia at high nitrogen loading rates, up to 7.5 kg N-NH4+ m-3 d-1 was obtained in a nitrifying activated sludge unit working at a hydraulic retention time of 1.3 h and 20°C. Bicarbonate, used as a carbon source for autotrophic microorganisms, allowed maintainance of a system very stable against different shocks due to point deficiencies of oxygen or other accidents. Ammonia conversion to nitrate was normally between 97 and 99.9%. Temporary accumulations of nitrite were quickly transformed into nitrate. The relative low specific conversion rate of the biomass in the reactor (0.5-0.7 g-N-NH4+ g-VSS-1 d-1 was compensated by the capacity of the unit to retain high concentrations of biomass (up to 15 g-VSS l-1) due to the excellent characteristics of the biomass (Sludge Volume Index of 12 ml g-VSS-1; Zone Settling Velocity of 9 m h-1. Present results show that activated sludge units can be operated efficiently as a high-rate nitrifying technology. This well-known, robust and easy to operate technology is a clear alternative to the airlift or fluidised-bed systems, which can be applied for the nitrification of high load wastewater at full scale.
KW - Activated sludge
KW - Ammonia loading rate
KW - Nitrification
KW - Sludge volume index
UR - http://www.scopus.com/inward/record.url?scp=0033135587&partnerID=8YFLogxK
U2 - 10.1016/S0960-8524(98)00141-2
DO - 10.1016/S0960-8524(98)00141-2
M3 - Article
AN - SCOPUS:0033135587
SN - 0960-8524
VL - 68
SP - 141
EP - 148
JO - Bioresource Technology
JF - Bioresource Technology
IS - 2
ER -