Patents Assigned to HDR Engineering, Inc.
  • Patent number: 6387264
    Abstract: A method for treating wastewater that generates a supernatant having a concentration of volatile fatty acids (VFAs) that falls within a specified range and a sludge that has percent total solids. The method includes the steps of providing a fermentation tank and a gravity thickener, operatively connected to the fermentation tank. The wastewater is permitted to flow continually or intermittently into the fermentation tank and a portion of the wastewater overflows the fermentation tank, thereby defining an overflow rate. The fermentation tank is subjected to anaerobic conditions and the wastewater in the tank is permitted to stratify so that sludge forms at the bottom of the tank. In addition the sludge is continually pumped from the bottom of the fermentation tank so that each stratification level within the fermentation tank corresponds to a sludge residence time that in turn corresponds to a range of VFA concentrations.
    Type: Grant
    Filed: December 5, 2000
    Date of Patent: May 14, 2002
    Assignees: CleanWater Services, HDR Engineering, Inc.
    Inventor: Robert James Baur
  • Patent number: 5980613
    Abstract: The present invention is a method and device for removing radon from groundwater without substantially reducing wellhead pressure. The pressurized radon stripper of the present invention has two principal components: a novel Venturi injector assembly which introduces air into a water process stream from a water source such as a well or the like; and a packed bed contactor which enhances air-liquid contact and serves as a gas-liquid separator. Over two thirds of the radon removal occurs in the Venturi injectors due to the intense gas-liquid turbulence in the throat of the Venturi valve.
    Type: Grant
    Filed: February 20, 1996
    Date of Patent: November 9, 1999
    Assignee: HDR Engineering, Inc.
    Inventor: Harold Steven Reiber
  • Patent number: 5755965
    Abstract: The present invention is a gas/liquid separator which is employed to remove free gases from a liquid. The invention is comprised of two concentric cones with a tapering annulus therebetween. The liquid stream to be de-gassed enters a tangential fluid inlet under pressure and passes downwardly in the tapered annulus. The inner surface of the outer cone has a plurality of stator vanes which minimize turbulence of the liquid and maintains helical motion. The outer surface of the inner cone has a plurality of orifices to receive gas bubbles. The outer surface of the inner cone is preferably roughened to thicken the gas boundary layer of this surface such that gas bubbles are more readily trapped thereon. The unit imparts a downward helical motion to the liquid flow between the outer cone and the inner cone.
    Type: Grant
    Filed: October 16, 1995
    Date of Patent: May 26, 1998
    Assignee: HDR Engineering, Inc.
    Inventor: Harold Steven Reiber
  • Patent number: D362902
    Type: Grant
    Filed: September 24, 1993
    Date of Patent: October 3, 1995
    Assignee: HDR Engineering, Inc.
    Inventor: Harold S. Reiber