ITB_WRS260536_Water_Reclamation_Facility_WRF_2_Rotary_Press_-_Exhibit_C_-_Engineering_Equipment_Comparison.pdf
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- Attached to
- Water Reclamation Facility (WRF) #2 Rotary Press
- Solicitation number
- ITB# WRS/260536
- Issued by
- Marion County, Orlando City, Florida
About this file
Exhibit C - Engineering Equipment Comparison for ITB WRS/260536
This is an engineering equipment comparison exhibit prepared by the City of Ocala Water Resources Department for the procurement of a backup biosolids dewatering solution at Water Reclamation Facility #2 (WRF #2) in Marion County, Florida. The document evaluates two primary dewatering technologies: rotary fan press and screw press systems, both designed to serve as backup equipment when the facility's primary Hiller centrifuge requires maintenance. The comparison addresses capital costs, operational characteristics, footprint requirements, and maintenance considerations for equipment with throughput capacity of 10-15 m³/hr. Equipment-only costs for rotary fan press systems range from $30,000 to $100,000 with full installation costs of $150,000-$400,000, while screw press systems cost $50,000-$150,000 for equipment only and $500,000 or more for complete installation. The selected equipment must be installed on the second floor of the Dewatering Building and comply with structural weight limitations of that location.
The comparison concludes that the rotary fan press is the preferred option due to its lower initial capital cost and significantly smaller footprint, despite being a newer technology with fewer active installations. Both systems achieve similar solids capture rates exceeding 95 percent, utilize polymer treatment, and operate at low noise levels with comparable energy consumption. The document recommends that prospective vendors provide references from current rotary fan press installations and that the City consult with active operators regarding performance and maintenance requirements. The screw press is identified as an established technology with higher throughput capacity suitable for larger plants, while the rotary fan press is deemed most appropriate for small to medium-sized facilities like WRF #2, with a caveat that the newer technology warrants additional investigation into long-term operational expectations and maintenance requirements before final procurement decisions.
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Goal: Looking for backup biosolids dewatering solution at WRF #2. Unit shall be placed on second floor of Dewatering Building and be used only when centrifuge is down for repairs.
Rotary Fan Press Lower capital cost - Correct Fewer moving wear parts so less maintenance costs
- This depends on which screw press you are comparing the fan press against.
Some screw press brands have multiple moving parts while others (FKC) do not have any wear items.
Smaller footprint - Correct Lower throughput volume – See below Newer technology - Correct 10-15 m3/hr = $ 30,000 to $ 100,000 equipment only. $ 150-400K full installation.
- Price and expected throughput will depend on the make/model selected which is dependent on the available footprint and allowable weight of the second floor of the dewatering building. Once this information is provided, we can help coordinate with vendors to specify the best unit and confirm pricing and expected throughput.
Screw Press Higher energy use – Dependent on selected make/model Higher capital cost – Correct Screw and screens can wear
- This varies by unit. Some screw press brands have multiple moving parts while others (FKC) do not have any wear items.
Larger footprint - Correct Higher throughput volume – See below Established technology - Correct 10-15 m3/hr = $ 50,000 to $ 150,000 equipment only. $ 500,000 + full installation
- Price and expected throughput will depend on the make/model selected which is dependent on the available footprint and allowable weight of the second floor of the dewatering building. Once this information is provided, we can help coordinate with vendors to specify the best unit and confirm pricing and expected throughput.
Exhibit C - Engineering Equipment Comparison ITB# WRS/260536
C -1
Reviewer I don’t see where we mention the throughput volume below
Reviewer I don’t see where we address the throughput volume below
Similarities Similar energy costs but with rotary fan using slightly less energy Similar solids capture rates
Both use polymer Both are quiet
Due to lower initial capital cost and smaller footprint, the Rotary Fan Press is the preferred option. This will not be the primary dewatering option.
- The rotary fan press and screw press both are low energy dewatering technologies with similar cake dewatering performance. The screw press is an established dewatering technology with a higher capital cost and larger footprint. Operation of the screw press is simple, and maintenance requirements vary between different manufacturers.
- The rotary fan press is a newer technology with a lower capital cost and smaller footprint. We recommend requesting a list of current installations from the rotary fan press manufacturer of choice. It would benefit the City to discuss the performance and required maintenance of the rotary fan press with operators actively utilizing the technology since it is a more recent dewatering technology.
- The selected backup dewatering technology at WRF 2 must be located on the second story of the dewatering building and not exceed the weight limitations of the structure.
- The rotary fan press is an appropriate alternative to the screw press and, due to its compact footprint, is a good option for the City.
Exhibit C - Engineering Equipment Comparison ITB# WRS/260536
C -2
Reviewer With the rotary fan press being newer is it prudent to emphasize the need to do a little more investigating on its current installations and point out that expected maintenance is a bit of an unknown?
Comparison table between Screw Press and Rotary Fan Press:
Feature Screw Press Rotary Fan Press Energy Consumption
Low (but slightly higher than rotary fan) Extremely low
Solids Capture Rate High (>95%) High (>95%)
Footprint Compact Very compact Noise Level Low Very low Throughput Capacity
Moderate to high (better for larger plants)
Low to moderate (best for small/medium plants)
Polymer Requirement Yes Yes
Maintenance Moderate (screw and screens wear) Low (fewer moving parts)
Sludge Type Tolerance
Handles oily/greasy sludge well
Best for standard sludge; less tolerant of oily/fibrous sludge
Market Adoption Well-established, widely supported Newer technology, fewer installations
Capital Cost Higher initial cost Moderate
Exhibit C - Engineering Equipment Comparison ITB# WRS/260536
C -3
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