biosolids management utilizing solar and thermal ... biosolids management utilizing solar and...
Click here to load reader
Post on 14-Apr-2020
Embed Size (px)
By Chris Enloe-Instrument & Supply, Inc. And Shannon Jones, P.E.-Utilities Engineer City of Fayetteville
Biosolids Management Utilizing Solar and Thermal Processes
What are biosolids? Biosolids are the treated finished product from the
wastewater treatment process. Billions of bacteria and other microbes thrive in the
wastewater facility environment where they consume the organic content from the wastewater stream and continually multiply.
To maintain optimum conditions and remove the nutrients absorbed by the microbes, a fraction of the microbial population is regularly removed. Referred to as Waste Activated Sludge (WAS).
When treated and processed, sewage sludge becomes biosolids which can be safely recycled and applied as fertilizer to sustainably improve and maintain productive soils and stimulate plant growth.
Fayetteville History In 2003, Fayetteville was forced to abandon land
application of waste sludge Landfill disposal was readily available and inexpensive By 2008, several area landfills no longer accepted AR
solids Landfill costs for those that would still take solids
skyrocketed almost 600% Fayetteville wanted a long-term, dependable, and
more sustainable solution
Why consider drying? Takes waste out of landfill Big volume reduction Beneficially useful product Self reliant If energy is managed, can be lower operating cost
AND smaller carbon footprint
Class A vs. Class B 40 CFR, Part 503 Class A biosolids contain no detectible levels of
pathogens. Class A biosolids meet strict vector attraction reduction requirements and low level metals contents, and generally have unrestricted use.
Class B biosolids are treated but still contain detectible levels of pathogens. There are buffer requirements, public access, and crop harvesting restrictions for virtually all forms of Class B biosolids.
Specific Options Compared
Option Selected Combined application of both Solar and Thermal
Drying Results in lower capital and operating cost – long term
Drying Sludge Provides Big Volume Reduction
Before – 100 lbs. Wet After – 20 lbs. Dry
Beneficially Useful Product Class A Product for Distribution/Sale Stockpile storage - low cost, long life
Spreadable – bulk fertilizer
1 Air flap 2 Exhaust fans 3 Ceiling fans
4 Electric Mole 5 Inside sensor 6 Outside sensors
3 2 5
First Step-Solar Houses 6 7
Thermo-System Active Solar Dryer
Fayetteville, AR Biosolids Management Site
Typical Solar House Drying Cycle
De-watered biosolids are trucked to the site from either WWTP
Solids are emptied into the “Unload Basin”
Solids are then loaded into the spreader or hauled directly into the houses with the skid-steer loader
Solids are then spread as evenly as possible inside the houses
Then the ‘moles’ are turned loose to do their thing!
After a variable weather-dependent drying period, the final product is ready for the next step
1 Sludge goes from hopper to drying chamber. 2 Steam to condenser. 3 Dry product to silo. 4 Heated by thermal fluid from heat exchanger.
Second Step – Thermal Dryer
Loading product into Thermal Building
Feed Conveyor Discharges into Feed Hopper
Feed Hopper – before initial use
Feed Hopper – initial fill
Screw Conveyors Transport Solids to the Dryer
Fenton Fenix Batch Dryer - Indirect Heat
Internal Rotating Assembly
Heat Exchanger – 15,000,000 BTUs
Natural Gas - >20,000 cfh capacity
Surge Bin – allows product to cool
Finished product ready for hauling/storage
Bulk Storage Silo
Performance Solar Houses Target 50% solids before
transferring to Thermal Dryer
Initial results before thermal dryer completion (summer months)
>80% Solids (Class B) 5:1 Volume Reduction 5:1 Weight Reduction
Thermal Dryer >90% Solids (Class A) 5:1 Volume Reduction 5:1 Weight Reduction
~60% Reduction in Costs vs. Landfill
Biosolids Management Site
Project Contributors City of Fayetteville (Design & Construction Management) CH2M HILL (Wastewater Operations) CDM Smith (Biosolids Management Study) McClelland Consulting Engineers (Geotech/Foundation Design) Instrument & Supply (Manufacturer’s Representative) Parkson / Thermo-System (Solar Equipment) Fenton Environmental Technologies (Thermal Equipment)
Slide Number 1 What are biosolids? Fayetteville History Why consider drying? Class A vs. Class B Alternatives Considered Specific Options Compared Option Selected Combination Drying Drying Sludge Provides Big Volume Reduction Beneficially Useful Product �Class A Product for Distribution/Sale Slide Number 12 First Step-Solar Houses Slide Number 14 Typical Solar House Drying Cycle Slide Number 16 Slide Number 17 Slide Number 18 Slide Number 19 Slide Number 20 Slide Number 21 Slide Number 22 Slide Number 23 Slide Number 24 1 Sludge goes from hopper to drying chamber. �2 Steam to condenser. �3 Dry product to silo. �4 Heated by thermal fluid from heat exchanger. Inlet Conveyor Loading product into Thermal Building Feed Conveyor Discharges into Feed Hopper Feed Hopper – before initial use Feed Hopper – initial fill Screw Conveyors Transport Solids to the Dryer Fenton Fenix�Batch Dryer - Indirect Heat Internal Rotating Assembly Heat Exchanger – 15,000,000 BTUs Natural Gas - >20,000 cfh capacity Surge Bin – allows product to cool Finished product ready for hauling/storage Bulk Storage Silo Performance Slide Number 40 Biosolids Management Site Project Contributors Questions?