Anoxic Selector Single Stage Nitrification Process Waste Water Plant Theory and Practise
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Transcript of Anoxic Selector Single Stage Nitrification Process Waste Water Plant Theory and Practise
Anoxic selector, single stage nitrification process
TCEQ Annual Water Quality Training Conference
October 18, 2006
Daniel Christodoss PhD, PE and Mike Jupe
City of WacoWater Utility Services
Presentation Review of TheoryReview of Theory
NitrificationNitrification DenitrificationDenitrification
Characteristics of bioreactorsCharacteristics of bioreactors Aerated or Aerated or OxicOxic UnUn--aerated or Anoxicaerated or Anoxic
Nitrification OptimizationNitrification Optimization Denitrification OptimizationDenitrification Optimization
PRACTICAL APPLICATIONS PRACTICAL APPLICATIONS @ WMARSS@ WMARSS
Nitrification Oxidation of ammonia to nitrite in Oxidation of ammonia to nitrite in oxicoxic conditions by conditions by
nitrosamonasnitrosamonas group (Optimum pH 8.0):group (Optimum pH 8.0): 2NH2NH33
++ + 3O+ 3O22 2H2H++ + 2H+ 2H22O + 2NOO + 2NO22--
Oxidation of nitrite by Oxidation of nitrite by nitrobactornitrobactor group:group: 2NO2NO22
-- + O+ O2 2 2NO2NO33-- (nitrates)(nitrates)
Oxygen Oxygen mechanicallymechanically provided by blowersprovided by blowers
Oxygen Consumption: 4.6 lbs of oxygen per lb of ammonia oxidizedOxygen Consumption: 4.6 lbs of oxygen per lb of ammonia oxidized to to nitrates (nitrates (energy intensive!energy intensive!))
Recover Nitrification Recover Nitrification CostCost: : DeDe--nitrificationnitrification
Nitrobes Nitrobes that Nitrify are facultative (that Nitrify are facultative (oxicoxic or anoxic). In anoxic they can or anoxic). In anoxic they can use NOuse NO33 in lieu of direct Oin lieu of direct O2 2 for cellular respiration and denitrifyfor cellular respiration and denitrify
Aerated (Oxic) Bioreactor
RAS (microorganisms)
WAS
O2 + Pollutants + MicroorganismsPrimaryEffluent
DenitrificationUsing biomass in wastewater as carbon source for Using biomass in wastewater as carbon source for
bacteria:bacteria:
CC55HH77NONO22 ++ 4.6 NO4.6 NO33-- 2.8 N2.8 N22 ++ 5 CO5 CO22
(biomass) (nitrates)(biomass) (nitrates) ++ 1.2 H1.2 H22O O ++ 4.6 OH4.6 OH--
Because within the anoxic reactor no dissolved oxygen is Because within the anoxic reactor no dissolved oxygen is supplied bacteria strip the oxygen molecule from the nitrates ansupplied bacteria strip the oxygen molecule from the nitrates and d consume the BOD present. consume the BOD present.
ADVANTAGES OF DENITRIFICATIONADVANTAGES OF DENITRIFICATION
Nitrate is reduced to nitrogen: Nitrate is reduced to nitrogen: NONO3 3 NN22 BOD is consumedBOD is consumed
Alkalinity is replenished saving the buffer for subsequent pH Alkalinity is replenished saving the buffer for subsequent pH sensitive biological reactionssensitive biological reactions
Un-aerated Bioreactor (Anoxic Zone)
RAS
WAS
PrimaryEffluent
NitrateRecycle
Anoxic Aerobic
Nitrification OptimizationSummary
Test nitrification rate occasionallyTest nitrification rate occasionally
Select appropriate SRTSelect appropriate SRT
Keep DO at min 2 mg/l @ peak conditionsKeep DO at min 2 mg/l @ peak conditions
Keep pH about neutral (optimal 7.5 to 8.5)Keep pH about neutral (optimal 7.5 to 8.5)
Provide sufficient alkalinityProvide sufficient alkalinity
Replenish a portion of the alkalinity consumed during Replenish a portion of the alkalinity consumed during the nitrification process by the nitrification process by denitrificationdenitrification
Denitrification Optimization Summary
Minimize DO in anoxic zone (< 0.2 mg/l)Minimize DO in anoxic zone (< 0.2 mg/l)
Maximize recycle capabilitiesMaximize recycle capabilities
Provide sufficient carbon source Provide sufficient carbon source
Ludzak - Ettinger Process
WMARSS Aerial
4 Digestors
4 final clarifiers5 aerationtanks
4 primary tanks
PelletizationFacility
TFDAF
cogen
Chlorination& Dechlor
SludgeLagoons
Brazos River
Filters
Admin
InfluentEffluent