On 2/1418 Mr. Earl Carter, a project designer with MCE's Fayetteville office, gave a presentation to the AWW&WEA Northwest Arkansas District's monthly meeting. His presentation centered around the Huntsville Biosolids Dryer project in Huntsville, Arkansas.

1. Presented February 14th, 2018 at the AWW&WEA District Meeting
Decatur, Arkansas
By Earl Carter, McClelland Consulting Engineers, Inc.
Biosolids Drying System

2. • Project Drivers
• Technologies Considered
• Bid Process
• How it Works
• Construction & Installation
• Operation
• Disposal of Biosolids
• Lessons Learned
Huntsville,AR -BiosolidsDryingSystem

3. Project Drivers
o Class B paperwork was cumbersome
o Land permits for Class B were limited
o Lime was in use to reach Class B; the
plant desired to eliminate use of lime
o Hauling/Landfill costs were not stable
o Class A methods made them better
stewards of the environment
o Class A made the plant more
sustainable
Huntsville,AR – BiosolidsDryingSystem

4. Heavily Considered the results of the Springdale study by MCE,
which compared many technologies
• Were already using lime and wanted to eliminate lime handling
• Did not produce a dry product
• Required the use of chemical addition
Lime Stabilization
Gas Dryer, Direct Head: Wyssmont & Thermaflight
• Thermaflight had low capital cost, small footprint & good energy
consumption
• Wyssmont selected due to:
 Company longevity/stability
 Low temperatures
 Low to no odors
 Small footprint
 Low energy consumption
 Simplicity
TechnologiesConsidered

5. Bid Process
• Standard advertisement for bids for equipment
• 30-day advertisement
• Specified around Wyssmont
• Briefly considered a direct heated belt dryer in use at a nearby industry at a
lower price
• Ultimately chose Wyssmont and sourced some equipment from local suppliers

6. How It Works
Broken down into two trains:
o Solids train
o Air handling train

7. How It Works: Solids Train
• Solids enter the top of the dryer
• Static wipers cause the solids to
transfer from tray to tray
• Transfer from tray to tray makes
small pieces without creating dust
• Dried solids are discharged into a
classifier
• Dried material is then discharged
into a receiving truck

8. Solids Train
Solids are metered with a pump to the top of the
dryer. Density is monitored to maintain best process
efficiency.

9. Solids Train
Solids drop through the trays while they are exposed to heated air, and dried.
Solids are classified, then conveyed to a truck. A 5-to-1 volume reduction is
realized.

10. How It Works: Air Train
• Fresh air enters the duct prior to entering the
heater
• The heater uses natural gas to warm the air
• A recirculation fan circulates the air through
the ducts
• A manifold distributes the air through the dryer
• Water is evaporated as air moves across the
wet material
• The air is filtered
• A portion of the air is exhausted
• The remaining air is recirculated, blended with
fresh air, and reheated

11. Air Train
Fresh air enters the duct, is pumped through the
heater, dryer, filter and duct system before being
recirculated.

12. Construction & Installation: Approx. 18 months
August 2015 April 2017

13. Operation
• Initially planned to operate only four days per week. It is
operated 4.5 to 5 days currently
• During fresh season, operated 7 days per week
• 24 hours per day operation when in use
• Dryer is not continuously manned. Logs are updated during
two shifts per day, per logging requirements of EPA 503
regulations
• Dryer runs unattended at night
• Requires approximately 20 man-hours per week for normal
operation
• SCADA system has 400+ alarms and is relentless
• One truck per week is hauled to a local farmer

14. Remote Monitoring with Instrument & Control
System
• Dryer Pressure
• Temperatures, multiple throughout
Operation
• Carbon monoxide and combustible gas monitors
• Solids flow meter with solids density meter provides lbs/hr signal
• Every point logged with historical data is saved to a non-volatile hard drive

16. Disposal of Biosolids
• Advertised to sell the Class A biosolids
• Sealed bids were received
• Low responsive bidder takes all product
• The low bidder is responsible for the container or truck;
one must be placed at the plant at all times during
operation
• $20/ton does not pay for operation, but is nice to have a
willing recipient as opposed to paying to dump it

17. Lessons Learned
• Biosolids do not handle like other products
• Know your biosolids and the EPA regulations
required to reach Class A EQ with them
• Sampling standards and methods are important. Be
consistent!
• A conservative approach is best when dealing with
new processes (only 7 dryers in the state) so that
when operational changes need to be made, you
have the flexibility

18. Lessons Learned
• Everything exposed to high temperatures should be insulated to 4
times the anticipated heat
• Public perception always has to be managed, for solids and air
• Always have a contingency plan for breakdowns
• Proper engineering saves time and money
• A solid manufacturer with good local representation can make or
break the project

19. QUESTIONS?
Biosolids Drying
System Tours Available
Special thanks to:
• Dryer Manufacturer – Wyssmont • Local Rep – Instrument & Supply
• Contractor – JL Bryson • Local Fabricator – RCW Welding
By: Earl Carter

20. THAT’S ALL
THANKS FOR WATCHING!