Process Monitoring for Biological and Chemical Nutrient RemovalOWEA 2016 PLANT OPERATIONS & LABORATORY WORKSHOP
October 27, 2016
Agenda
Why Consider Nutrient Removal?
Nitrogen Monitoring & Removal
Phosphorus Monitoring & Removal
2
Why Nutrient Removal?
Required by Discharge Permit
Improve Water Quality (avoid future limit)
Increase Revenue (water quality trading)
Stabilize Process
Save Energy
Recover Nutrients (P)
3
Energy Intensity Benchmarking
4
Joint WEF/WERF Webcast: Net‐Zero Energy Solutions for Water Resource Recovery Facilities
Wednesday, October 29th, 2014
1,412
1,9341,853
1,955
973
1,2491,118
1,202
0
500
1,000
1,500
2,000
2,500
BasicSecondary
Nitrification BNR ENR
kW
h / M
G
Typical
Best Practice
Human
WWTPPlantsIndustry
Agriculture
Rivers &
lakes
Sediments
Phosphate
rock
Discharge
SedimentationTectonic
uplift
Fertilization
Detergent
WeatheringRunoff
Mining
Cornel et al (2009)
P
Recovery
X
P Removal and Recovery
Nitrogen Monitoring
6
Cabinet Analyzer
7
Ion Selective Electrode
8
Specifications – IQSN Nutrient ISEs
Specification Ammonium Nitrate Potassium Chloride
Measuring Range
mg /L (as N)*
0.1 to 100 /
1.0 to 2,000
0.1 to 100
1.0 to 1,000
0.1 to 100
1.0 to 1,000
0.1 to 100
1.0 to 1,000
Resolution
mg /L (as N)*0.1 / 1.0 0.1 / 1.0 0.1 / 1.0 (as K) 0.1 / 1.0 (as Cl)
Response Time
min.< 3
9
Response Time
10
Automation of Wastewater Treatment Facilities, 3rd Edition, WEF MOP-21, WEF Press, Alexandria,
VA, 2007.
Optical
11
ISE vs. Optical Nitrate Monitoring -
Optical ISE
Measuring range, mg/L as N 60 / 150 0 to 1,000
Resolution 0.01 0.1
Pressure resistance, bar 1 0.2
Power Consumption, W Up to 8 0.2
Response time (t90), min. Programmable < 3
Temperature measurement No Yes
Additional Parameters / probeCOD/BOD/TOC,
NO2, TSS
NH4, K, Cl
Warranty (probe), yrs 2 2
Warranty (electrodes), yrs NA 1
Nitrogen Removal
13
The Microbiological Nitrogen Cycle
AOB
NOB
OHO NO2-
Clarifier
Nitrogen Removal Configuration
15
Anoxic Oxic
RAS
WW
NO3-N
NO3-N NO3-N
NH3 NO3NO3 N2
NO3
NH3
3-4 Q NO3-N
BOD
IMLR or NRCY
Delaware County RSD
Anoxic Oxic
A NA N O HO
Denitrification Process Control Chart
17
4-Stage Bardenpho
BOD
NH3-N
NO3-N
Internal MLSS Recycle
3-4 Q NO3-N
Anoxic
Aerobic
Aerobic AerobicAnoxic
Distance
RAS
Q
Methanol
or Glycerin
3-5 mg/L
TN
Denitrification Monitoring – WSSC Seneca
5 x NitraVis 701 TS (1 in each train) w/
supplemental air cleaning (MIQ/CHV)
Goals:
Effluent < 4.0 mg N/L (permit)
Effluent < 3.0 mg N/L ($300k credit)
Minimize Methanol
19
N
Step Feed Denitrification
20
NYC DEP
63 x NitraVis 701 IQ
Goals:
Target Effluent TN = 7 to 8 mg N/L
Monitoring of oxic zone nitrate
Feed forward – Feedback control of
carbon addition (NIC-NOT)
Phosphorus Monitoring
21
Orthophosphate (PO43-)
Environmental P is Phosphate
Soluble P is orthophosphate
Colorimetry is the primary method of
detection
Phosphorus Characterization
TP
OP
Orthophosphate Analyzer
Low reagent consumption
Suitable for outdoors
Automatic calibration
Integrated permeate pump
Filter module
24
Technical Specifications
Range
(mg P / L) Accuracy
Response
time
(min.)
Detection limit
(mg P / L)
Reagent
Replenishment
Lo: 0.05 to
15 mg P / L 2% or 0.05
mg P / L< 5 0.05 mg P / L 2.5 L / 4 mths.
Hi: 1 to 50
mg P / L
25
Phosphorus Removal
26
How is ‘P’ Removed?
1. Biological
2. Chemical
Basic concept:
‘P’ soluble ‘P’ Particulate
‘P’‘P’
Chemical P Removal
• Pre-precipitation
• Simultaneous
precipitation
• Post precipitation
Fe/ Al Fe / Al Fe / Al
‘P’ ‘P’
Fe / Al
Chemical Dosing Control
Manual
Flow-proportioned (Feed Forward)
Feedback with analyzer
29
Feedback Control Example
‘P’
Fe
P700
0.65 0.05
9000.50%
0.10
0.61
HOLD
Chemical Dosing System Operation
31
Phosphorus Accumulating Organism (PAO)
Anaerobic Aerobic
Ortho-P
3 x Infl. Ortho-P
BODPHB
Storage
BOD Oxidized
Concentrations
in Bioreactor
Location in Bioreactor
Net P
Removal
RAS
P-Rich
WAS
PAO
VFA
P
PAO
P
A / O Process
Flow Sheet – GC Sugar Creek
Effluent
Ultraviolet
Disinfection
Process Control - ORP
Summary
There are many compelling reasons to consider nutrient removal
Multiple reliable online monitoring technologies are available for
nitrogen monitoring.
Nitrogen removal is achieved through modification of the well-known
activated sludge process to exploit the microbiological nitrogen
cycle
Online phosphorus monitoring requires a cabinet analyzer but the
technology is improving to reduce maintenance and cost
Phosphorus removal can be achieved chemically or through
enrichment of phosphate accumulating organisms (PAO)
36
Questions?
37