Converting Waste Agricultural Biomass into a Resource - UNEP

Detailed Process Description
7. Rice straw/hulls pass through a shredder
8. Shredded material passes to a steam explosion where dilute sulfuric acid
is added to the material
9. The material then passes to a counter current extractor containing NaOH
solution. This process will place the silica and the lignin in solution
10. The lignin-silicate solution passes to our ultrafiltration system where the
silicate solution passes through the membrane and the lignin solution is
concentrated
11. The material leaving the counter-current extractor is washed and
hydrolyzed, fermented and converted to fuel ethanol, or
12. The lignin fuel separated by the ultrafiltration system is used to provide
energy for the operation of the plant.
Main Products
Fuel Ethanol, Silica, Metal Finishing, Water Soluble Oil & Synthetic Lubricant
Coolants, Latex and Latex Paint, Pulp and Paper, Chemical & Metallurgical,
Textile & Dye.
Operation and Maintenance Requirements
Colusa facility consumes approximately 130,000 tons of waste biomass
annually, producing 12.5 million gallons of ethanol and 16,800 tons of
silica/sodium oxide.
Environmental Considerations
Social Considerations
Uses low cost plant waste rather than high-cost corn and grain to produce
ethanol for fuel and various by-products such as lignin and silica. Highly
efficient fermentation steps produce only trace amounts of CO2. Simply
leaving the straw on the ground for soil nutrition requires chopping it up and
re-flooding the fields with water.
Investment and Operating Cost
The company bought a patent—U.S. Patent No. 5,735,916 in October 2004,
with the $40 million cost of capitalizing this relatively small facility, decided to
take the company public.
The customized harvester collects the waste, bursts the straw's cylindrical
tubes and chops it into 3/8-inch pieces. The material is blown into trailers that
hold from nine to 14 tons and it is transported to one of company’s three
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