David,

 

Thanks for the information.  We currently don’t have Neuros blowers as an option in the MBR RFQ/RFP package, due to the expense of the blowers, but we still plan to look into this option and could change the MBR system scope later if the City decides it wants Neuros blowers.  I think the first step is to talk to the PUD to see how much of the capital cost they would be willing to pay for the City to have the more efficient blowers, and then perform a preliminary life cycle cost analysis.  If the numbers come out relatively close or in favor of the Neuros blowers, the City can then decide if that is what they want to specify.

 

On a related subject, we currently have a fixed grid diffuser system specified in the MBR RFQ/RFP package.  I know you have a strong preference for the retrievable diffuser racks.  However, the arrangement of diffusers in those racks is quite dense, such that the air would not be evenly distributed throughout the basins without supplemental mixing.  This would require the use of mixers in the aerobic zone (additional equipment and energy) to distribute the air.  Also, the aerobic zone would then be completely mixed.  To obtain similar treatment as a plug flow aeration basin, the aerobic zone would need to be compartmentalized into two or three cells with baffles, and each cell would need its own mixer.  The alternative is to have a fixed diffuser grid that distributes the air and provides enough air to keep solids in suspension, allowing for plug flow in a single long aerobic zone.  As you are aware, the tank would need to be drained (we would include a sump, guide rails, etc. to drop a submersible pump to dewater the tank back to the EQ basin) to gain access to the fixed diffuser grid.  Also, Aqua-Aerobics is the only manufacturer that we’ve been able to identify so far that manufactures diffuser racks that are retrievable with a small davit crane that can be hand or motor operated.  It is not clear at this time if they will provide those diffusers separately from their package SBR system.  We recommend specifying a fixed grid diffuser system in the MBR RFQ/RFP package.  This does not preclude making a change later if the City decides to stick with the retrievable diffuser racks and would represent a deduct, rather than an addition to the original proposal price.  As part of the proposal alternate, we’ve allowed them the option to make use of those existing diffusers if they so choose.  Furthermore, there could still be a use for those diffuser racks in the aerobic digesters, particularly if supplemental mixing is included to enhance denitrification.

 

 

• Size.  The size of the blower, 100 Hp motor, VFD, HMI, and other electrical items is half the size of our existing blowers.
• Noise.  The system is so quiet you can stand next to it and talk in a normal voice.  This does not include start up and shut down when the system is bypassing air to atmosphere.
• Estimated O&M.  Randy reviewed the O&M manual and we spoke with one of the operators.  It appears that the operations requirements and maintenance is minimal.  Bearings are air so no oil buy, change or clean up and dispose of. There are five micron filters to change and if the environment was prescreened they should last for at least one quarter.
• VFD operation.  The operation of the blower is from 40% to 100% and efficiency do not drop at any point.  I only herd this in statement and needs verified.
• Weight.  The total weight of the system was 1500 pounds.  This is the weight of our 100 Hp motor alone.
• The system does not need any footing or foundation to be customized  for it.  Do to the low vibration and enclosure design the system can be brought in and using adjusting pads provided leveled then discharge pipes installed.
• Twenty % reduction in energy.  This was not verified by us and should be looked in to.

• Cost.  The 100 HP blower system costs about $100,000.00.  This is the entire cost to include MCC and VFD.  Treatment Equipment rep stated that Alderwood had credits from PUD that made up for the extra capital costs.
• O&M.  Although there is not much cost for maintenance we did note that you can not work on the system and if a part fails you will just replace it.  The motor for instance would need replaced if a bearing fails.
• Noise.  During start up and shut down the blower is very noisy!  A jet airplane.
• Electronics.  At this time the system does not use Allen Bradley or seimen plc, and IO cards.  The company is working on that portion however and it is expected that they will be providing the PLC, HMI and other parts with Allen Bradley in the near future.