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
  • Patent number: 5385673
    Abstract: A method of treating wastewater biosolids by destruction of pathogens and indicator organisms to meet or exceed USEPA Process to Further Reduce Pathogens standards. The method first depresses the pH to below 5, followed by pH increase to 12 or higher, causing an exothermic reaction and heat of hydration. The mixture is placed within a confined volume to maintain the temperature at or above 55.degree. C. for at least two hours. The mixture can be dewatered for a higher percent solid characteristic. The material is then tested and if test results indicate, the material is approved by the Environmental Protection Agency for human contact. The biosolid materials are suitable for general nutrient values with minimal regulatory restriction and other beneficial uses.
    Type: Grant
    Filed: September 8, 1992
    Date of Patent: January 31, 1995
    Assignee: Hazen and Sawyer, P.C.
    Inventor: Robert E. Fergen