Post on 30-Jan-2023
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Optimization through Solids Measurement
Heli Karaila product manager
Measurements Metso
Timo Riippa Metso partners
Instrumentation, Process Control & Automation Conference
Brisbane 2012
Optimization through Solids Measurement
• Sludge general
• Optimization possibilities with the online measurements
• Metso Waste Water Sludge treatment online measurements
Metso TS
Metso LS
The wastewater
treatment industry
has a mandate to
protect the water
environment.
In fulfilling this
mandate, wastewater
treatment plants
produce large
quantities of residual
solids, commonly
referred to as sludge.
Amount of the Sludge in the
waste water plant• Each reduced BOD7 kg creates 0,7 –
1,2 kg solid material in the waste
water plant. www.ympäristö.fi
• Generally,solids production rates
range between 0.2 and 0.3 kg/m3 of
wastewater treated Turovskiy I. and Mathai P. ( 2006)
Solids removal is needed in
the waste water plant
• Solids removal is normally defined
in the waste water plant’s
environmental permission as one of
the key parameters ( Suspended
Solid in the leaving water )
• The only way solids can be
removed from the waste water plant
is via sludge dewatering
• Solids circulation should be avoided
inside the plant
Costs of the sludge removal
• The cost for treatment + disposal of
sludge in European countries has
been estimated to reach, on average,
approximately 500 € per tonne of dry
mass, according to the type of
treatment and disposal . www.iwawaterwiki.org
• The sludge management costs are
about 40 to 50% of the total
wastewater treatment costs. Turovskiy I. and
Mathai P. ( 2006)
Optimization possible only with
online measurements
• the laboratory based measurement
are always too late and it is not
possible to create control on the basis
of the laboratory measurements
• There is a need for a reliable online
measurements
There are following technologies in mostly in
use for measuring solids online in the
waste water area:
• Optical ( scatter, absoption)
• Optical that utilized compined signals
• Coriolis
• Torque
• Microwave
Example of the Maintenance needs of
scatter, absorption measurements
Instrumentation Testing Association suspended Solids and Turbidity
measurements maintenance benchmark study MBS99SS-
001p (1999 )
Sludge treatment online measurement
benefits / optimization
• Sludge Pumping from Primary & Secondary
Sedimentations
• Digester Feed
• Dewatering
• Dewatered sludge “Dry Cake”
• Reject water TSS measurement
Sludge pumping control on primary
& secondary sedimentations
• Target:
– Keep total solids of the sludge
high as possible from the begging
of the sludge treatment process
by measuring total solids accurate
way and controlling the pumpings
based on the measurements
• Results:
– Increased pumping capacity
means higher water processing
volumes and postponed
investments
– Harmonized operations
– Optimized quality
– Optimized and reduced costs of
the sludge pumping
13
Digester Feed
• Target
– maintain optimum sludge
solid to digesting process
• Results:
– Improved process control and
significant savings
– Increased sludge digestion
time to produce more biogas.
– Decreased heating energy
>> more electric energy can
be produced and transferred
for the aeration of biological
reactors
16
Dewatering• Target:
– Accurate measurement for
polymer dosage- and
dewatering equipments
control
• Results:
– Reduced polymer costs
– Stabilized quality of both the
dewatered sludge and the
centrate water.
– Reduced sludge
transportation costs
– Improved incineration
efficiency when the sludge is
burned
– Lowered energy consumption
and maintenance costs of
dewatering equipment19
More than 20% savings on polymer costs
• Optimum polymer dosage can
be defined only by a reliable
solid content measurement
and saving of 20% in polymer
costs can be achieved.
• Depending on process
capacity, the return of
investment can be surprisingly
short.
• In middle size WWT plant (PE=
500 000) ROI can be just a
months.
20
Feed sludge ~ 2%TS
+ polymer
Centrate water
< 0,1 TS%
Cake solids
~ 25 TS%
Dry Cake• Target:
– Accuracy total solids results for
dewatering- and incinerator control
• Results:
– Efficient combustion of the
wastewater solids while maintaining
fossil fuel consumption.
– Operator can proactively adjust the
feed rate of both the natural gas and
the fuel oil based on the incoming
solids of the sludge.
– Significant energy cost savings.
– A new higher pressure sensor model
for pressure rating ( PN100 / Class
600 / JIS63K) available
22
Laboratory measurement is not enough
0
1000
2000
3000
4000
5000
6000
30.11.10 0:00 5.12.10 0:00 10.12.10 0:00 15.12.10 0:00 20.12.10 0:00 25.12.10 0:00 30.12.10 0:00
Mittari Labra
0
500
1000
1500
2000
2500
3000
3500
19:12 0:00 4:48 9:36 14:24 19:12 0:00
Mittari Labra
Quality control of
centrate water
based on infrequently
taken lab samples
is not adequate
Lab sample represents
centrate quality at that
specific moment:
- After a half an hour
the situation can be
completely different!
mg/l
mg/l
Metso LS Laboratory
online measurement Laboratory
24
Finding out the optimum polymer dosage
2011 TRa25
– Polymer flow – Sludge flow – Total suspended solids
Polymer saturation point
Polymer flow
Sludge flow
Total Suspended Solids
Online polymer test possible
Control application feedback
based on Metso LS measurement
26
0
500
1 000
1 500
2 000
2 500
3 000
21.1. 22.1. 23.1. 24.1. 25.1. 26.1. 27.1.
mg
/l, kg T
S/h
0,0
2,0
4,0
6,0
8,0
10,0
kg P
E/ t T
S
TS-kuorma LINKO 4. REJEKTI SS Polymeeri
0,0
2,0
4,0
6,0
8,0
10,0
12,0
0,0
500,0
1 000,0
1 500,0
2 000,0
2 500,0
22.2. 23.2. 24.2. 25.2. 26.2. 27.2. 28.2.
kg
PE
/ t T
S
mg
/l, k
g T
S/h
TS-kuorma LINKO 4. REJEKTI SS Polymeeri
Manual control Automatic control
--- sludge to drying --- polymer --- total suspented solids
Automatic control : Polymer dosage is managed on the basis
of centrate quality within given limits
Saving possibilities by reject
water TSS minimizing
- Minimize the circulating material
- Dewatering costs minimizing (
polymer , dewatering unit costs )
- Circulating solids needs pumping,
chemicals etc. again in the plant
- Circulating material is challenging for
the wastewater plant
Sludge online measurements
Metso
• Microwave technology ;
– Metso Total Solid
measurement ; Metso TS
• Laser and LED technology ;
– Metso Low Solid
Measurement; Metso LS
Date Author Title30
Benefits gained using microwave
technology
• A most representative measurement -
transmitter measures the time of flight of a
microwave signal in all the process
medium.
• Microwave measurement does not react
to changes in the composition of solids.
• Reliable single-point calibration
• Practically maintenance-free
• Measurement range 0-40 %
Supreme Measurement Accuracy
• Excellent correlation to
laboratory results.
• Reduced need of
laboratory analyses.
• Typical fluctuation of
primary sludge solids.
• Solids measured and
controlled independently
of discharge sequences.
31
Metso LS
- total suspended solids measurement• Total suspended solids 0–
5000 mg/l – if over 5000
please contact Metso
• Entrained air index
Customer statement:
”The first measurement
system that really works in
centrate water”
2011 TRa32
Metso LS
for reliable centrate TSS measurement
• So far no reliable measurement in the market
– Accuracy & reliability have been major problems
• It is very important to know the quality of centrate water
– For choosing the right polymer type
– For dosing the polymer economically
– For process monitoring
• Laboratory follow up is not enough
– Based on laboratory it is not possible to tune polymer dosing
successfully
• Reliable measurement enables big savings in
– Polymer dosage
– Centrifuge usage
– Management of plant internal solids cycle
Date Author Title33
Online measurements key to the
optimization of the waste water plant
• Today there are reliable online
measurements available for the
wastewater optimization; example
Metso TS and Metso LS.
• With the online measurements the
optimization / cost reductions are
possible