adsorption, ion exchange, oxidation, nitrification, denitrification, and/or disinfection) for final polishing the secondary effluent in order to meet the effluent
discharge standards.
2. Innovative single-sludge activated sludge system: It is a biological activated
sludge process system involving the use of one suspended activated sludge
solid going through aerobic and anoxic zones for carbonaceous oxidation, nitrification, denitrification, and phosphorus removal. The single-sludge activated
sludge system is commonly a continuous flow system using sedimentation
clarification. The Lenox Institute of Water Technology (LIWT) has developed
three innovative single-sludge activated sludge systems all for carbonaceous
oxidation, nitrification, denitrification, and phosphorus removal: (a) continuous
flow single-sludge system using flotation clarification; (b) sequencing batch
reactors (SBR) using sedimentation for carbonaceous removal and nutrient
removal; and (c) SBR using flotation for carbonaceous removal and nutrient
removal.
3. Denitrification followed by flotation clarification: The process involves the
reduction of nitrates and nitrites to nitrogen gas through the action of facultative
heterotrophic bacteria. In suspended-growth separate-stage denitrification processes, nitrified wastewater containing primarily nitrates is passed through a
mixed anaerobic vessel containing denitrifying bacteria. Since the nitrified feedwater contains very little carbonaceous materials, a supplemental source of
carbon (such as methanol, sugar, acetic acid, ethanol, or other compounds) is
required to maintain the denitrifying biomass. This supplemental energy is
provided by feeding methanol, for instance, to the biological reactor along with
Fig. 3.21 A suspended-growth activated sludge system uses primary flotation clarification and
secondary flotation clarification
3 Biological Processes
137
discharge standards.
2. Innovative single-sludge activated sludge system: It is a biological activated
sludge process system involving the use of one suspended activated sludge
solid going through aerobic and anoxic zones for carbonaceous oxidation, nitrification, denitrification, and phosphorus removal. The single-sludge activated
sludge system is commonly a continuous flow system using sedimentation
clarification. The Lenox Institute of Water Technology (LIWT) has developed
three innovative single-sludge activated sludge systems all for carbonaceous
oxidation, nitrification, denitrification, and phosphorus removal: (a) continuous
flow single-sludge system using flotation clarification; (b) sequencing batch
reactors (SBR) using sedimentation for carbonaceous removal and nutrient
removal; and (c) SBR using flotation for carbonaceous removal and nutrient
removal.
3. Denitrification followed by flotation clarification: The process involves the
reduction of nitrates and nitrites to nitrogen gas through the action of facultative
heterotrophic bacteria. In suspended-growth separate-stage denitrification processes, nitrified wastewater containing primarily nitrates is passed through a
mixed anaerobic vessel containing denitrifying bacteria. Since the nitrified feedwater contains very little carbonaceous materials, a supplemental source of
carbon (such as methanol, sugar, acetic acid, ethanol, or other compounds) is
required to maintain the denitrifying biomass. This supplemental energy is
provided by feeding methanol, for instance, to the biological reactor along with
Fig. 3.21 A suspended-growth activated sludge system uses primary flotation clarification and
secondary flotation clarification
3 Biological Processes
137