Title: Optimization of the Sludge Dewatering System
1Optimization of the Sludge Dewatering System
- Present by Rui Zhang
- Civil Engineering Department
- Client Niagara Falls Wastewater Treatment Plant
2Contents
- Client and Site Background
- Overview of Project Approach
- Parameters Used for the Analysis
- Economic Modeling
- Test Results
- Conclusions and Recommendations
3Client the City of Niagara Falls Wastewater
Treatment Plant
- Home Niagara Falls, New York
- Birthday 1977
- Service Population 61,840
- Flow Design-48mgd, peak-85mgd, current-35mgd
- Due to the significant industrial loading for
this plant during 1960s and 1970s,
physical-chemical treatment was chosen instead of
biological treatment. - In 1994, EPA referred to it as the most
successful operation of any of the municipal
carbon treatment facilities in the country.
4Site Background
5Existing Sludge Management System
6Proposed Sludge Management System
7Project Objective
- Feasibility study
- Find the scenarios where the alternative is an
economically preferred option - Determine the payback
- Evaluate the space requirements
- Develop a schematic design
8Overview of Project Approach
- Review the pilot test data
- Examine the existing plant equipment, structure
and procedures - Select equipment and size the equipment within
the existing system - Develop economic modeling to do feasibility study
- Calculate payback period and give recommendations
9Parameters Used for the Analysis
- Solid Content Based on Pilot Test Data
- Disposal Cost Production Rate
- Current Dewatering Performance and Financial
Parameters and Assumptions
10Pilot Test Data from 1994
11Disposal Cost Production Rate
12Current Dewatering Performance and Financial
Parameters and Assumptions
13Economic Analysis Factor
- Debt Service 20-year period
- Interest Rate 6 as the city controller
recommended, range 0-12 - Capital Recovery Factor, range 0-15
- Disposal Cost and Production Rate
- Actual Capacity of the Pressure filtration System
(percent of post-lime sludge treated by the new
system per year, range - 0-100
14Equipment Selection
- One Mini-Miser DC450 sludge processing system
from RECRA Inc. was chosen as the secondary
dewatering system due to the available pilot test
data, low OM cost, compact design, automated,
compatibility with the existing facilities and
acceptable capital cost. - The dimensions height-7.23ft, width-9.84ft,
length-26.3ft (available space 41ft by 45ft) - The unit cost 450,000
- OM cost 30,000/year
15Mini-Miser Dewatering System
- Automated Feeding System
- Pressbags
- Grooved Racks
- Hydraulic Cylinders
- Collection Trays
- Belt Conveyor
16Proposed Plan View of the New Pressure Filtration
System
17Proposed Position of New Inclined Conveyor and
Pressure Filtration System
18Estimated Project Capital Cost
- Equipment cost
450,000 - General construction
- Install press hopper
1, 200 - Concrete steel support 1,
000 - Conveyor system
1, 200 - Electrical
45, 000 - Miscellaneous construction cost 2, 000
- Subtotal
504, 000 - Contingency (10)
56, 000 - Estimated Project Capital cost
560, 000
19Economic Modeling by Using MPL Modeling System
- Objective Function
- Minimize AA1-A2
- Subject to
- 0lt CRFlt 15 0lt X1lt
100 - X1 X2 1 DCgt 0 PRgt
0 A0 -
- Where
- A1 is the annualized cost of the new dewatering
system. (BFPPFS) - A2 is the annualized cost of the current
dewatering system. (BFP)
20Summary of Variable Definition
21Summary of Macro Definition and Formula
22Sensitivity Analysis
- It was used to determine what effect each
variable will have on the objective function when
the variable increases by one unit. - In many applications, the values of a models
parameters may change. If this occurs,
sensitivity analysis often makes it unnecessary
to solve the problem again in order to obtain the
new optimal value to the objective function. This
is of great use, especially when the linear
program is very large and resolving it can take a
long time.
23Test Results
24Payback Period
- Annual Disposal Cost Savings (13.8/0.351) wet
ton/day 29.826.25/wet ton 5day/week52weeks/y
ear 80,000/year - Subtract the OM cost (30,000), the net Disposal
Cost Savings is 50,000 - Payback Project Capital Cost / net Annual
Disposal Cost Savings 560,000/50,000 11 years - Based on the maximum 6 years payback expectation
without subsidy on this project, the disposal
cost would have to be at least 40/wet ton. (Or a
production rate would be at least 21dry ton/day).
25Limitations
- More recent pilot scale testing should be used
for more accuracy. - More alternatives should be checked for
additional dewatering. - The analysis is based on a conceptual design and
a full-scale design is needed for accurate cost
estimation.
26Conclusion
- Available space is adequate for the new
equipment, a Mini-Miser DC450. - It is cost-effective in the long term for the
City of Niagara Falls to add pressure filtration
to the dewatering system. The annualized
dewatering cost savings from this upgrading
project is 1, 140 for 2000 year. - The calculated payback in 2000 year is 11 years.
To get a payback of 6 years, the disposal cost
would be 40/wet ton at least or the production
rate would be 21 dry ton/day with all other
parameters hold. -
27Recommendations
- The city of Niagara Falls WWTP pursue the
upgrading sludge dewatering project as long as
more favorable scenarios can be expected - The economic model is strongly recommended for
use in feasibility studies of potential
technologies. - A pilot scale secondary dewatering project should
be implemented such that the project costs and
potential revenues can be more accurately
established. - EPA innovative or alternative status should be
checked for more favorable technologies in
future. - Make application for Clean Water State Revolving
Fund. One-third to one-half of the market
interest rate can be saved for qualified project.
28Questions?
- Thanks very much for your time