Patents by Inventor M. David Rickard

M. David Rickard has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Method for treatment of digester supernatant and other streams in wastewater treatment facilities
    Patent number: 4076515
    Abstract: Digester supernatants and/or liquors from sludge dewatering are reacted with an excess of an alkaline reagent having a stronger cation than the ammonium ion and the reaction product is separated into a solution containing aqueous ammonia and solids. The aqueous ammonia derived from the separation stage is heated by free steam under a lowered pressure to free ammonia in gaseous form. The ammonia as a gas, or adsorbed in water, or adsorbed in an acid, or as an acid salt is then mixed with conventionally dried sludge to increase the nitrogen content of the sludge from approximately 1-2 percent to as high as 10 percent.
    Type: Grant
    Filed: July 9, 1975
    Date of Patent: February 28, 1978
    Inventor: M. David Rickard