E. I. du Pont de Nemours & Co., Inc.
The two major non-aqueous wastes from the Adiponitrile (ADN) manufacturing process are a spent catalyst solids (Solids) and ADN tars from a wiped film evaporator (WFET). The Solids were historically collected in a water slurry tank, transported via truck to a belt filter press, filtered, loaded into lever packs, and transported to a landfill or incinerated at another site. The WFET was diluted with a waste organic fluid and injected down a deepwell.
This $10MM project provided facilities to combine both waste streams into an organic slurry and transport the material via pipeline to the on-site incinerator. Timing was expedited to coincide with the startup of the site incinerator.
The project eliminated the use of deepwell injection for organic wastes, eliminated approximately 15 gpm of water used in the transport and filtration of the solids, and eliminated the on-plant trucking and off-plant transportation of the hazardous solids. The consumption of organic diluent was reduced by 1/2, freeing the remainder for power generation and sales.
The slurry pipeline was designed to operate at a viscosity 500cp to minimize the amount of organic diluent required. This improved the fluid handling characteristics by decreasing the solids settling rate in the pipes. Due to the solids content and relatively high viscosity, a hybrid of the technologies for transporting Ti02 slurries and viscous polymers was employed.
The waste stream has substantial BTU value, so it is pumped directly to the afterburner chamber of the site incinerator to reduce the demand for natural gas. Low NOX burners are used in the incinerator to minimize NOX formation.
This project terminated the practice of injecting organic wastes down deepwells and eliminated the need for transporting untreated hazardous solids on public roads.
Details of Reductions
Additional Information :
The cost of incineration cannot complete economically with deepwell injection. In spite of our conviction that deepwell injection of organic waste is environmentally safe, we have responded to public concern by voluntarily eliminating that practice. The commitment to eliminate deepwell injection of organic waste was made to the EPA so that the time and expense of developing a deepwell no migration case be avoided.
Cost saving to DuPont are in the form of avoided costs of regulatory compliance and the cost of chemical fate and modeling studies which could easily run into millions of dollars.