Patents Assigned to Hazen & Sawyer, P.C.
  • Patent number: 5916448
    Abstract: A method is provided for improving the dewatering and odor reduction characteristics of a liquid wastewater sludge, sediment, or soils to ultimately form a dewatered solid residual that includes nutrition enhancement of a resultant material that is suitable for distribution and marketing, and for incorporation in a fertilizer blend. The material meets Class A pathogen reduction by achieving disinfecting conditions. The method includes the addition of selective acids and bases to the liquid sludge which forms insoluble precipitates, and enmeshes the solids in the sludge to form a granular product. The method's applicability includes municipal, agricultural, food processing, industrial liquid and semi-liquid sludges, sediments, and soils.
    Type: Grant
    Filed: August 22, 1997
    Date of Patent: June 29, 1999
    Assignee: Hazen & Sawyer P.C.
    Inventor: Robert E. Fergen
  • Patent number: 5429750
    Abstract: A method to remove pathogens from dewatered sludge and to reduce vector attraction that includes the steps of raising the pH 12 of the sludge above 12, subjecting the sludge to low ambient (near zero) pressure and/or elevating the shear pressure on the sludge after the sludge has been treated with a bulking agent to increase stiffness. Exposure to a vacuum enhances pathogen destruction and helps remove odiferous gases for vector control.
    Type: Grant
    Filed: June 25, 1993
    Date of Patent: July 4, 1995
    Assignee: Hazen & Sawyer, P.C.
    Inventor: Richard Steele