filterclear to meet low phosphorus consent · bolsover ‘p’ trial caroline huo1, lynn smith2 and...
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Bolsover ‘P’ Trial
Caroline Huo1, Lynn Smith2 and Karen Young3
Bluewater Bio1, Yorkshire Water2, Arup3, UK
FilterClear To Meet Low Phosphorus Consent
The BIG Phosphorus Conference and Exhibition – Removal and Recovery. 4-5th July 2017
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The CIP(2) scheme was directed
by the EA to demonstrate best
endeavours to achieve 0.1 mg/l
total phosphorus with a variety of
technologies
➢ FilterClear Technology
➢ Site information
➢ Trial performance
➢ Trial observations
➢ Lessons learned
➢ Recommendations
Introduction
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• Down-flow, depth filtration
• Four media, coarse to fine
– High effluent quality
– High solids holding capacity
– Prevent solids breakthrough
– Long runtime
• Light to heavy
– Stratification after backwash
• Ferric dosing at inline static mixer
for rapid mixing
• Flocculation in the headspace of
FilterClear (no purpose built
flocculation tank needed)
FilterClear: High Effluent Quality @ High Solids Loading
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• Compact, skid-mounted systems
• Wide range of filter diameters
• Standard design & control philosophy
• Offsite manufacturing & testing
• Package plant delivery
• Quick installation, plug & play
FilterClear - Offsite Manufacturing
• High filtration rate 25 m/h to 35 m/h
• Smaller footprint
• Less material, lower embodied carbon
• Average operating pressure: 0.5 bar
• Backwash initiation pressure: 0.9 bar
• Low energy consumption, lower
operational carbon
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FilterClear: TP Removal with single point dosing
➢ Large trickling filter site (Longbridge STW @ Severn Trent)
➢ Single point Ferric dosing upstream of PST
➢ FiterClear influent TSS 18mg/L, effluent TSS 6 mg/L
➢ FilterClear influent TP 0.7mg/L, effluent TP 0.3mg/L
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PSTs
Trickling
Filters
Humus
Tanks
FFT
Ferric
sulphate
FilterClear
Stage 1
Stage 2
Outfall to river
Caustic
80%-100%0-20%
B/W
Bolsover STW - Overview
Parameter Value
FFT 54 l/s
PE 10,000
Ave final effluent SS 27.2
95%ile final effluent SS 58
Consented SS, 95%ile 70
Control Dose
Stage 1 P load
profile
3.5 kg Fe/kg TP
Stage 2 Flow
proportional
12 mg/l as Fe
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Bolsover Site Layout
Stage 1
ferric
Stage 2
ferric
Caustic
FE
p/s
Clean water tank B/W water tank
Ferric Caustic
FilterClear
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FilterClear Results – TP Sample data
Biofilm
Stage 1@ 3.5 2.0 1.5
Stage 2@ 12 6 0
Media
topped
up
0
1
2
3
4
5
6
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8
TP
mg/l
TP in TP out target TP mg/l
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FilterClear Results – Iron, TSS data
0
10
20
30
40
50
60
70
0
1
2
3
4
5
6
7
8
9
10
TSS
mg
/l
Tota
l iro
n, m
g/l
Total iron in Total iron out TSS in TSS out
Biofilm
Stage 1@ 3.5 2.0 1.5
Stage 2@ 12 6 0
Media
topped
up
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Trial Observations – FilterClear feed flow
0
10
20
30
40
50
60
70
80
L/s
Bolsover FFT and FilterClear feed flow
FFT, l/s FilterClear, l/s
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Trial Observations – Solids generation
➢ FilterClear solids holding capacity
3 to 4 kgTSS/m3 media
➢ Underestimated solids generation
from stage 2 dose
Design basis,
kg/d, filter run
time
Measured
average
conditions
Estimated
maximum
conditions
TSS (mg/L) 37 122 122
Flow (m3/d) 5046 3639 5046
TSS (kg/d) 187 444 616
TSS (kg/h) 7.8 18.5 25.7
Solids holding capacity,
kgTSS/m3 media
3.5 3.5 3.5
Total media volume 7.2 7.2 7.2
Filter runtime, h 3.2 1.4 1.0
➢ Seasonal impact observed
➢ Jar tests at each site
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Trial Observations – Backwash control
➢ Filter designed to backwash on pressure
differential
➢ Pressure controlled backwash was not
sufficient in higher flows and also
morning flow peaks.
➢ A layer of flocs developed during low
flows
➢ The backwash return had to be restricted
during storm events to 6 l//s to meet
consented FFT +10%.
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Operational issues – Instruments
➢ All instruments required additional maintenance
➢ The ortho P instrument was not sufficiently reliable
for control purposes
➢ The iron monitor frequently alarmed for high iron,
inhibiting ferric dosing or shutting the plant down
Inlet biosolids
Ortho P feed
strainerIron monitor
inlet solids
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Operational issues – Biofilm
➢ Stage 2 ferric dose
wasn’t optimised
➢ High iron
environment
➢ Biofilm growthPlenum
Plenum cover
Clean water tank
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TP Achieved at High 2nd Point Ferric Dosing
Conditions:
2nd Point dosing: At high Ferric dose of 30 mg/L
• Flow rate 17l/s (30% FFT)
• Backwash frequency: 2 hours
FilterClear Influent
(pre ferric dosing)
FilterClear Influent
(after ferric dosing)FilterClear effluent
TSS
mg/l
TP
mg/l
Total Iron
mg/l
TSS
mg/l
kg solids/
kg ferric dosed
TSS
mg/l
TP
mg/l
Total Iron
mg/l
55 3.8 4.7 131 2.5 < 3 <0.08 < 0.2
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Trial Observations – Media loss
• Media loss noted after a few months
• The reason for the media loss was a combination of increased
viscosity of water in cold weather and biofilm growth due to
shutdowns.
• Backwash adjusted with temperature factor
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Lessons Learned
➢ Thorough site audit is essential to understand the existing plant performance and site constraints
➢ Fully account for solids loading, including effluent TSS and chemical sludge production.
➢ Jar tests can be very useful for diagnose and trouble-shooting
➢ Chemical dosing control need to be adjusted in response to any changes
➢ Instrument selection, location, cleaning & maintenance
➢ Feed pumping control
➢ Hydraulic checks, including storage and backwash control & return
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Trial Conclusions and Recommendations
➢ FilterClear is capable of achieving TP of 0.1mg/L,
but not without challenges
➢ Online instruments need to be maintained and
calibrated regularly
➢ 2-3 months for optimisation
➢ Plan for up-skilled operators and increased
maintenance
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Big P Conference – Bolsover P Trial
Thank you
Any Questions?
Presented by:
Caroline Huo, Principle Process Engineer, Bluewater Bio, [email protected]
Karen Young, Process Engineer, Arup, [email protected]
Lynn Smith, Technical Specialist, YWS, [email protected]