Abstract Liquid sewage and waste, such as manure and/or sewage sludge, are treated to destroy pathogenic bacteria and remove offensive odors to make the material usable as a plant nutrient and soil conditioner. The liquid sewage is thoroughly aerated within a cone-shaped, pressurized vessel by injection of a jet of compressed air tangentially to the side walls of the vessel into contact with the liquid sewage. The vortex motion and agitation created by injection of the compressed air disintegrates the larger solids of the sewage or sludge so that the compressed air can permeate the material to a greater degree. A head of compressed air is built up above the liquid level in the pressurized vessel, which, on opening of a discharge valve in the lower end of the pressurized vessel, forces the contents of the vessel through an outlet pipe connected to the vessel through the discharge valve. The material may be used as is or discharged onto a pile of sawdust, ground bark or straw for composting. After an adequate composting period, the material can be packaged for sale or used directly as a soil amendment and fertilizer. To insure thorough sterilization of the material in the case of sewage waste, a metered amount of sulfuric acid is injected into the material being treated to lower the pH of the material to pH 3.0 or less. After an exposure of several minutes to this low pH environment to destroy pathogenic bacteria, the material is treated with a neutralizing agent to increase the pH to an optimum value for use as a plant food.
A method of treating liquid material consisting essentially of sewage and/or manures having solids therein to make the liquid material usable as a plant nutrient and soil conditioner, comprising: feeding the liquid material into a cone-shaped pressure vessel, injecting a stream of pressurized oxygen-containing gas into the pressure vessel near the lower end thereof and tangential to the side walls of the conical portion of the vessel to impart a centrifugal motion to the liquid material and impinge the pressurized gas against the solids in the liquid material with sufficient force to break the solids into small particles, the gas thoroughly aerating the material and pressurizing the vessel with the oxygen-containing gas to a pressure ranging from 4 to 15 psi above the liquid level in the pressure vessel, injecting sulfuric acid into the liquid material in an amount sufficient to adjust the pH of the liquid material to a pH of 3.0 or less for sterilization thereof, and readjusting the pH to approximately 6 to 7, and discharging the liquid material from the vessel by the gas pressure formed above the liquid level in the vessel onto a compost material selected from the group consisting of sawdust, ground bark, peat-moss, straw and wood chips.
Claim 2
Independent Claim
205 words
A method of treating liquid material consisting essentially of sewage and/or manures having solids therein to make the liquid material usable as a plant nutrient and soil conditioner, comprising: feeding the liquid material into a cone-shaped pressure vessel, injecting a stream of pressurized oxygen-containing gas into the pressure vessel near the lower end thereof and tangential to the side walls of the conical portion of the vessel to impart a centrifugal motion to the liquid material and impinge the pressurized gas against the solids in the liquid material with sufficient force to break the solids into small particles, the gas thoroughly aerating the material and pressurizing the vessel with the oxygen-containing gas to a pressure ranging from 4 to 15 psi above the liquid level in the pressure vessel, injecting sulfuric acid into the liquid material in an amount sufficient to adjust the pH of the liquid material to a pH of 3.0 or less for sterilization thereof, and readjusting the pH to approximately 6 to 7, and discharging the liquid material from the vessel by the gas pressure formed above the liquid level in the vessel onto a compost material selected from the group consisting of sawdust, ground bark, peat-moss, straw and wood chips.
Claim 3
Dependent Claim
25 words
The method of claim 1 wherein the sulfuric acid is introduced into the liquid material prior to introduction of the material into the pressure vessel.
Claim 4
Dependent Claim
41 words
The method of claim 1, including metering the rate of flow of liquid material fed to the pressure vessel and injecting said sulfuric acid into the liquid material being treated relative to the amount of liquid material in the pressure vessel.