Upload
others
View
5
Download
0
Embed Size (px)
Citation preview
1
Optimizing Polymer Preparation to Enhance Sludge Dewatering
Dr.-Ing. Julia B. Koppspeaker of the german specialist group of “sludge dewateringand conditioning” (DWA KEK 2.3)
2
DWA Fachausschuss AK 2 „Stabilisation, Konditionierung, Eindickung, Entwässerung und Entseuchung von Schlämmen“
Technical Guide DWA M 366Mechanical Dewatering of Sewage Sludges2013
DWA Specialist Group
Technical Guide DWA M 350Polymer Preparation2014
Technical Guide DWA M 383Sludge Characterisation2008
Technical Guide DWA M 381Sewage Sludge Thickening2007
3
dewaterabilty depends on sludge properties
Quelle : DWA M-366 Dr. Denkert
Fee
d Q
[m³/
h]; P
oly
[kg/
t DS
]; D
S-c
ake
[%]
Load
[kg
DS
/h] i
n ce
ntrif
uge
DS-cake [%] Feed [m³/h] Polymer [kg/t DS] Load [kg DS/h]
Sludge A Sludge B Sludge C Sludge D
4
Influence of sludge structure
DSdewatered ~ 30% DSdewatered ~ 20%
5
Only the free water can be separated
6
DS(A) = measurement of free water content
0.00
0.02
0.04
0.06
0.08
0.10
dryi
n g r
ate
[g/
h]
0.0 1.0 2.0 3.0 4.0 5.0
masswater/ massDS [g/g]
Y = 0.0656 + 0.00205296XEMS = 8.93501e-008R2 = 0.970
DS(A) = 100 / ( 1 + 2,15 ) = 31,8 %
A free water
15
20
25
30
35
40
in fu
ll sc
ale
proc
esse
s [%
]dr
ied
solid
s af
t er
dew
ater
ing
15 20 25 30 35 40
dried solids at point A of the drying curve - DS(A) [%]
Y = 1.777 + 0.9437X
centrifuges
filter presses± 1,5 %
7
Sludge Conditioning
Flocculation of digested sludge
8overdosage
DS-cake [%] digested sewage sludge
9
Dripping Test
10
good = min time + max filtrate
Example – Dripping Test - Dewatering
11
streaming potential measurement
Stempel
PTFE - Meßgefäß
Probe
Elektroden
Partikel adsorbiert
Partikelnicht adsorbiert
Scherebene
(Bley / Muetek)
requirement: optimal polymer conditioning
12
25°CPolymer 1: shear-stabel
Polymer-demand 14,5 kg AS/t DS
Polymer-dosage 13 kg AS/ t DS
DS dewatered = 26,8% DS
Degree of separation =98,9 > 95%
DS(A) = 28%
Polymer 2: not suitable
Polymer-demand 8,6 kg AS/t DS
Polymer-dosage 12,5 kg AS/ t DS
DS dewatered = 24,3% DS
Degree of separation = 89,2 < 95%
DS(A) = 28%
Polymer Preparation
Optimal preparation is needed for an optimal dewate ring
Maturing time: > 45 min
Dilution: 2 chamber system
Dosing: within 4 hours after maturing
Control: DS of polymer solution13
polymeres Flockungsmittel Ladungsbildung Hydratisierung und Handelsware Streckung der Moleküle
Polymerproduct
Non dilutedcharging streching
14
viscosity - maturing
-CH 2 -CH -CH 2 -CH -
C= O
N H 2
C= O
O
CH 2
CH 2 N (CH 3 ) 3
+ Cl - +el. conductivity
emulsion cross linked
emulsion linear
powder polymer
Maturing time
Maturing time & Usability of polymer-solution
15
0
20
40
60
80
100
120
140
0 2 4 6 8 10 12 14 16 18 20 22 24
Zeit [h]
Eta
[mP
as]
Emulsionspolymer linear 0,5% WS-Ansatz
Emulsionspolymer vernetzt 0,5% WS-Ansatz
Time [h]
Vis
cosi
ty [m
PA
S]
Maturing time & Usability of polymer-solution
short preparation 10 min
optimal preparation 45 min
after 4 hour maturing
Influence of polymer concentration
17
165
180
250
310
40
45
52
58
0
10
20
30
40
50
60
70
0
50
100
150
200
250
300
350
0,1 0,3 0,5 0,7
min
imu
m r
ipe
nin
g t
ime
[m
in]
ma
xim
um
wo
rkin
g t
ime
[m
in]
Concentration polymer solution [%]
Control of maturing time and the optimal working time of PolyChemie CP 66U
working time maturing time
18
Equipment3-Champer-Systems
don‘t use:
19
Recommendation: 2 - Chamber - System
20
Polymer-Preparation-Pumps
� Polymer-preparation-pumps work solely with liquid products
� Gear pump produces high mixing energy
� +: needs no further pumping
� - : maturing time ist too short
� Connected maturing tank is recommended
PolymerSolutionWater
Water
Mixing Pump
PolymerSolution
Polymer-product
21
Connected maturing tank is recommended!
Polymer-Preparation-Pumps
22
First contact
Polymer - Water!needs high turbulence
Water
powder polymer
Inline mixer / ejector pump
Liquid polymer Mixing tank
23
Quality - Control
• Take 500 gr. retain sample per delivery(date/ charge number)
• Liquid Polymer ~ 48% Active Substance (AS), rest = oil and add ons
• Powder Polymer ~ 95% AS, rest = citric acid, salt and add ons
• Check concentration of polymer solutionby DS measuring
• Documentation of consumptionkg merchandise / t DSkg AS / t DS
• Control maturing time with signal colourfrom sewage drain
• Check polymer demand by conditioning tests
concentration of polymer solution – DS solution
24
DS
of p
olym
er s
olut
ion
[%]
AS in polymer solution [%]
Summary
25
• Only free water can be separated by mechanical dewatering → DS(A)
• The proper selection and preparation of polymer is required to achieve good dewatering results.
• The building of shear stable flocs by conditioning is important.
• The polymer-demand and the dewatering result depend strictly on quality of polymer preparation. Mostly the maturing time is disregarded.
• By measuring viscosity of the polymer solution the maturing time can be determined. The time of utilization depends on pH and polymer-concentration.
• It will be recommended to prepare polymer solution for 45 min and use the solution during 4 hours.
• For polymer-preparation 2-Chamber-Batch-Systems will be recommended
• Check concentration of polymer-solution frequently by measuring DS
• Check polymer-consumption 4 time a year anddocument operating data accurate.
Dr.-Ing. Julia B. Kopp - tel. +49 5174 / 922 043 - www.kbkopp.de
Questions
26