ekoton industrial group. a comparison between the sludge dewatering equipment in municipal and...
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A comparison between the sludge dewatering equipment in municipal and industrial wastewater treatment plantsTRANSCRIPT
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A comparison between the sludge dewatering equipment in municipal and industrial wastewater
treatment plants
Report plan
Brief description of the compared equipment
Comparison of the equipment for the small capacity WWTP
Comparison of the equipment for the middle capacity WWTP
Comparison of the equipment for the large capacity WWTP
Conclusions
Compared sludge dewatering equipment
Operation principle of centrifuges
Operation principle of belt filter press
Operation principle of screw dehydrator
Stationary ring
Cake removal
Movalble ring
Supporting frame
Plate
Dehydration zone Thickening zone Sludge with
reagents
Filtrate removal
Stationary ring
Movalble ring Screw
Supporting frame
Technological features of the represented sludge dewatering
equipment
Compared parameter
Centrifuge Belt filter-press Screw dehydrator
Odor spread and sanitary condition in the shop
The construction is closed, but still general ventilation
is necessary
Reliable ventilation system and every-shift equipment
washing are necessary
The construction is closed, but still general ventilation is
necessary
Necessity of wash water
Little amount is necessary (at the end of the operation
cycle for the washing of inner aggregate surface)
Much water under the pressure of 5-7 atm. is necessary (20-40 % of
sludge volume, that is fed to dewatering)
Some water under the pressure of 1-2 atm. is
necessary (about 1-2 % of sludge volume, that is fed to
dewatering)
Noise and vibration pollution
High noise level values – more than 70 dB. The
arrangement of special foundation is necessary in
order to prevent the transmission of vibrations
Aggregate itself is noiseless, but there is quite a loud noise from the washing
nozzles, nevertheless it is within the permissible
limits
There is virtually no vibration and periodical noise (1-2 min/h) from the washing
nozzles is within the permissible limits
Compared parameter
Centrifuge Belt filter-press
Screw dehydrator
Dehydration of greasy and oily sludge
Possible in a wide range of concentrations
Possible only at low concentrations
Possible in a wide range of concentrations
Dehydration of sludge with high content of abrasive substances
Possible, but will cause the rapid abrasion and wear of the rotor
and the inner surface of the housing
Possible in a wide range of
concentrations
Possible in a wide range of concentrations, but the
resource of the screw will be less (20-25 thousand of hours
instead of possible 30 thousand of hours)
Visual inspection of the process
No access Easy access Easy access
Filtrate quality At comparable doses of flocculant and medium speed of rotor it is higher than that of FP
and dehydrator by 20-50 %
Commonly within the limits of 200 –
700 mg/l
Commonly within the limits of 200 – 700 mg/l
Technological features of the represented sludge dewatering
equipment
Initial data for the comparison of the sludge dewatering equipment
Parameter Small WWTP Medium WWTP Large WWTP
Capacity 800 m3 / day
45’000 m3 / day 280’000 m3 / day
Volume of sludge 8 m3 / day 450 m3 / day 2800 m3 / day
Humidity of the initial sludge
97,5 % 97,5 % 97,5 %
Operation time of equipment per day
9 h 16 h 23 h
Cost comparison for dewatering of the sludge in small capacity
WWTP
2,4
2,6
2,8
3
3,2
3,4 3,29 3,37
2,83 М
лн
. гр
н
Capital costs
Centrifuge Belt filter press
Dehydrator
0
1
2
3
4
54,68
2,99 2,55
Мл
н. г
рн
Operational costs for 10 years
Centrifuge Belt filter press
Dehydrator
Cost comparison for dewatering of the sludge in
medium capacity WWTP
0
2
4
6
8
10
12
5,23 5,28
10,75
Мл
н. г
рн
Capital costs
Centrifuge Belt filter press
Dehydrator
0
5
10
15
20
25
30
35
40 35,78
5,76 9,085
Мл
н. г
рн
Operational costs for 10 years
Centrifuge Belt filter press
Dehydrator
Cost comparison for dewatering of the sludge in large capacity
WWTP
11,5
12
12,5
13
13,5
14
14,5 14,25
12,68 М
лн
. гр
н
Capital costs
Centrifuge Belt filter press
0
20
40
60
80
100
120
140 125,4
14,9
Мл
н. г
рн
Operational costs for 10 years
Centrifuge Belt filter press
The most appropriate equipment for the sludge dewatering in small capacity WWTP is Screw dehydrator because of less energy consumption and repair/maintenance costs than of other represented equipment.
The capital and operational costs of Screw dehydrators will be much higher in the medium capacity WWTP than of small capacity WWTP.
The lowest operational costs in the medium capacity WWTP are of the Belt filter press.
The use of screw dehydrators in the large capacity WWTP is inexpedient.
Operational and capital costs of the Belt filter press in the large capacity WWTP are lower than of centrifuges.
Conclusions
