Improving Phosphorus Removal with Magnetite Assisted ...
Transcript of Improving Phosphorus Removal with Magnetite Assisted ...
Improving Phosphorus Removal with
Magnetite Assisted Settlement.
BioMag and CoMag
Adam Brookes, Bernie Glanville, Stephen Tomlin, Jane Youdan.
Anglian Water, Northumbrian Water, Wessex Water.
The BIG P conference, Manchester, 5th July 2017
National Collaborative Project
Improving Phosphorus Removal with Magnetite Assisted Settlement
Content:
• Process background – the use of magnetite
• Trial sites and results
• Common findings
Process Background
• Magnetite assisted settlement
• Both BioMag and CoMag can be retrofitted
• Magnetite recovery system
• Co-Mag:
– Use of magnetite to assist with settlement after secondary
treatment (trickling filters or activated sludge)
– Separate floc tank and settlement tanks
• BioMag:
– Addition of magnetite into activated sludge
– Use of existing FST
• Shear mill
• Magnetic recovery drum
• Return of magnetite to
process
• Removal of excess
sludge
Magnetite Recovery
System
Trials
• Part of the AMP6 national phosphorus removal technology trials.
• Market Harborough STW, Anglian Water. CoMag
– Oxidation ditch, followed by CoMag, PE = 23,000
• Esh Winning STW, Northumbrian Water. Co-Mag
– Trickling filters, PE = 5,000 (100% of flow)
• Bowerhill STW, Wessex Water. BioMag
– ASP, PE treated = 4,000 (50% of site flow)
CoMag
Market Harborough STW
Market Harborough STW
Overview of CoMag Process Installation
• CoMag installed post ASP, fed from feed/overflow chamber
Note: upstream chemical dosing for P removal to target of around 1 mg/L
Market Harborough STW
CoMag Installation
Market Harborough STW
Results of CoMag Trial
Influent total P
Average
(mg/l)
Effluent total P
Average
(mg/l)
Effluent total P
Min
(mg/l)
Effluent
total P
Max
(mg/l)
% removal
1.13 0.17 0.06 0.4 85
Market Harborough STW Summary
• The principal issues encountered during the trial were the
robustness and reliability of individual components that are
fundamental to successful and stable operation.
• Numerous problems with polymer make up and dosing system.
• Duty only on trial plant so single point of failure
• The performance of the clarifier was identified by EWT as being
deficient, limiting the overall performance of the plant
• Relatively high chemical use per volume treated and load
removed (polymer and ferric)
• Excellent performance when everything was working correctly
CoMag
Esh Winning STW
Esh Winning STW
Overview of Comag Process Installation
• Comag retrofit between the trickling filters and the humus tanks
• Diversion of flows post trickling filters into wet well then pumped
into package plant for ferric and caustic dosing
• Flow passing through several reaction tanks mixing with sludge
returns and polymer
• Flow passing into humus tanks for settlement and sludge
recovery
• Initial hydrostatic valves for desludge of humus tanks. Required
replacement with progressive cavity pumps due to blockages
• Sludge wastage and magnetite recovery process
• Note; no upstream chemical dosing for P removal
Esh Winning STW – Process Layout
Esh Winning STW
Impact of Process Stability on Final
Effluent
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
24
-May
31
-May
07
-Jun
14
-Jun
21
-Jun
28
-Jun
05
-Jul
12
-Jul
19
-Jul
26
-Jul
02
-Aug
09
-Aug
16
-Aug
23
-Aug
30
-Aug
06
-Sep
13
-Sep
20
-Sep
27
-Sep
04
-Oct
11
-Oct
18
-Oct
25
-Oct
01
-Nov
08
-Nov
15
-Nov
22
-Nov
29
-Nov
06
-Dec
mg
/l P
ho
sp
ho
rus FE total P
FE SRP
P 1
SRP 1
P 2
SRP 2
Level of Control
Esh Winning STW
The Good and the Bad
When stable, good settlement
and visibility within the humus
tankWear on PC pumps after 3
months
Esh Winning STW – Summary of Trial
• Major equipment failures during the trial; shear mill, transfer pumps and
dosing systems, resulting in an unstable process.
• When the plant was working correctly the final effluent quality was good
with total P levels down to 0.22mg/l and less.
• SRP values were less than 0.1mg/l unless the chemical dosing system
failed.
• If the dosing system failed the final effluent quality deteriorated within 24
hours.
• If the magnetite sludge was allowed to settle for more than 2 hours in
the tanks a vactor was required to re-suspend or remove it.
• Further investigation of the control and set up of the technology required
BioMag
Bowerhill STW
Bowerhill STW
BioMag Installation
• Aeration lanes
• PE approx. 4000
• Primary ferric ahead of the PSTs
• Additional secondary ferric dose into aeration lanes
• Polymer dose at outlet of aeration lanes
Primary
Settlement
Tanks
Sludge Storage Tank
ASP
Inlet Works
Final Effluent to River
Final
Settlement
Tank
RAS
BioMag® Unit… …
SAS
Shear Mill
Magnetic Drum
SAS Buffer Tank
Recovered
Magnetite
SAS
Addition of
magnetite
Bowerhill STW
BioMag Results
• Results (1 year period):
– Average Total P = 0.23 mg/l
– Average SRP = 0.10 mg/l
Bowerhill STW
BioMag Summary
• Other findings:
– The polymer did not show any impact on results
– Due to settlement of magnetite in the aeration lanes, it was
challenging to maintain the suggest magnetite:MLSS ratio
– Secondary ferric dose was critical to low P concentrations
• The BioMag system could be used to increase treatment capacity,
but this was not looked at as part of this trial.
Common Findings
BioMag & CoMag
Common Findings
• Total P concentrations of between 0.17 mg/l and 0.23 mg/l
• No benefit seen from use of polymer in BioMag
• Issues with reliability of process
• Some issues with replacement parts for magnetite recovery system
• Issues with settlement of magnetite
• Magnetite measurement method was not user friendly
Any Questions?