The N-VIRO Fuel™
Terry J. Logan, Ph.D.
Organic Wastes as Biomass Fuel
There are ~ 40 million tons of sewage sludge
produced in the U.S. annually.
There are ~ 600 million tons of collectable
There are ~ 150 million tons of organic municipal
solid wastes (garbage).
There are high tip fees for sewage sludge
(> $100/ton in the NE, ~ $25-40/ton nationally)
There are federal grants for treatment of
There is increased interest in using organic
wastes as biomass fuels.
Fuel and Ash Content of
Organic waste Energy value Ash content
(kJ/kg) (% dry
Wood 19,000 0.5-1.5
Manure 15,000 10-25
Food waste 16,000 – 21,000 1-20
Sewage sludge 16,000 – 28,000 20-40
M unicipal solid waste 3,000 – 14,000 20
The N-VIRO Organic Waste
Alkaline mineral by-products (fly ash,
cement kiln dust, lime kiln dust) are mixed
with dewatered sludge or manure.
Stabilization is achieved by a combination
of high pH, heat and drying.
USEPA approved parameters for Class A
disinfection of sewage sludge are pH 12
for 72 hours, 52 0C for 12 hours, and
solids > 50 %.
The N-VIRO Soil Product
The product of the N-Viro stabilization process is a dry,
granular material with soil-like physical properties.
It is used as an agricultural soil amendment as a liming
material, low analysis fertilizer and source of organic
It is also used for land reclamation, and as a blend with
compost to make horticultural topsoil.
Properties of N-VIRO Soil
Organic matter con tent (% dry weight) 30
Liming value (% dry weight) 25
Total nitrogen (% dry weight) 1
Total phosphorus (% dry weight) 0.5
Total potassium (% dry weight) 0.1
Total sulfur (% dry weight) 5
Total calcium (% dry weight) 12
Total magne sium (% dry weight) 2
Total boron (mg/kg d ry weight) 500
Total mangane se (mg/kg) 200
Total zinc (mg/kg) 200
Solids content (% by weight) 60
The N-VIRO BioDry™ Process
Heated air is used to dry the sludge or manure
mixed with alkaline by-products.
Drying is done in a rotary drum dryer.
Less by-product is used compared to the
conventional process since part of the required
heat for disinfection comes from the dryer.
Final solids content of the final product can be
Final product is more uniform in particle size.
The N-Viro BioDry™ Process
Sludge/fly ash leaving the mixer and entering the rotary drum dryer
Lessons Learned from the
Traditional sludge dryers are prone to fires
and explosions because of the volatile
nature of sludge.
Operational BioDryers have had not
experienced these problems.
Research showed that the addition of
mineral by-products to sludge raised
ignition temperatures above air-drying
The N-VIRO Fuel™ Process
The N-Viro Fuel process is a modification of the
The process uses less mineral by-products than
the BioDry process, and recycles some of the
dried material to further reduce the mineral
component and increase the organic content
and fuel value.
The process can be optimized for higher solids
than produced for an agricultural product.
The N-Viro Fuel process still meets EPA
requirements for Class A disinfection.
Characteristics of N-VIRO Fuel™
Has physical characteristics similar to coal.
Solids content is 70-90 % and can be controlled.
BTU value is 4,000-7,500/lb.
Ash content is 20-40 %.
Sulfur content is ~ 1 %.
Heavy metals are similar in concentration to that
of coal; coal is higher in arsenic and sludges are
higher in copper and zinc.
Biologically stable, low odor potential, and fully
Synergy with Coal Fired Power Plants
Sludge production and power plant operations are both 24/7.
If the N-Viro Fuel® facility is co-located at the power plant, waste
heat from the power plant can be used to run the dryer.
The N-Viro Fuel® process will utilize the power plant’s fly ash as
N-Viro Fuel® contains lime which can offset limestone addition for
The exhaust gases from the BioDryer contains ammonia which
might be utilized for NOx reduction.
Sewage sludge and other waste organics are low in sulfur compared
to most coals.
There should be opportunities to earn CO2, NOx and SOx credits.
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