Process to stabilize wastewater sludge

A method for treating wastewater sludge so that a stability based upon achieving a significant microbial population, conductivity level and percent solids, is developed rapidly, is provided for indefinitely and is independent of climatic conditions. A dewatered sludge that has not been treated (i.e., raw) or a sludge that has been treated to a PSRP level or a sludge that has been treated to a PFRP level, i.e., pasteurized or sterilized sludge when still in a wet condition, i.e., between 12%-30% solids, or when in a dry condition, i.e., between 30%-60% solids, is mixed with alkaline adsorptive materials to reduce odor, to increase the percent solids and to facilitate granulation, is adjusted to a mildly alkaline pH, and is adjusted to an ionic conductivity which will allow the sludge to mature rapidly when seeded with a beneficiating microbial flora. This process will reduce the pH of a high alkaline treated sludge, e.g., often above pH 12, to a physiological pH of between 7 and 9.5 or will raise the pH of a treated acid sludge to a similar range so that microbial activity can proceed to facilitate stability. Heat may be applied to the mixture to accelerate the carbonation and aid the overall drying process. The granular product, substantially due to its active microbial population, is useful as an agricultural product and topsoil blend.
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Abstract/Description: A method for treating wastewater sludge so that a stability based upon achieving a significant microbial population, conductivity level and percent solids, is developed rapidly, is provided for indefinitely and is independent of climatic conditions. A dewatered sludge that has not been treated (i.e., raw) or a sludge that has been treated to a PSRP level or a sludge that has been treated to a PFRP level, i.e., pasteurized or sterilized sludge when still in a wet condition, i.e., between 12%-30% solids, or when in a dry condition, i.e., between 30%-60% solids, is mixed with alkaline adsorptive materials to reduce odor, to increase the percent solids and to facilitate granulation, is adjusted to a mildly alkaline pH, and is adjusted to an ionic conductivity which will allow the sludge to mature rapidly when seeded with a beneficiating microbial flora. This process will reduce the pH of a high alkaline treated sludge, e.g., often above pH 12, to a physiological pH of between 7 and 9.5 or will raise the pH of a treated acid sludge to a similar range so that microbial activity can proceed to facilitate stability. Heat may be applied to the mixture to accelerate the carbonation and aid the overall drying process. The granular product, substantially due to its active microbial population, is useful as an agricultural product and topsoil blend.
Subject(s): 210/609
71/9
71/13
71/22
210/613
210/631
210/667
210/710
210/752
210/764
210/916
Date Issued: 1994-01-04
Title: Process to stabilize wastewater sludge.
Name(s): N-Viro Energy Systems Ltd., assignee
Burnham, Jeffrey C., inventor
Type of Resource: text
Genre: patent
Publisher: United States Patent and Trademark Office
Other Date: Date Filed: 1992-02-20
Date Issued: 1994-01-04
Physical Form: application/pdf
Extent: 24 p.
Abstract/Description: A method for treating wastewater sludge so that a stability based upon achieving a significant microbial population, conductivity level and percent solids, is developed rapidly, is provided for indefinitely and is independent of climatic conditions. A dewatered sludge that has not been treated (i.e., raw) or a sludge that has been treated to a PSRP level or a sludge that has been treated to a PFRP level, i.e., pasteurized or sterilized sludge when still in a wet condition, i.e., between 12%-30% solids, or when in a dry condition, i.e., between 30%-60% solids, is mixed with alkaline adsorptive materials to reduce odor, to increase the percent solids and to facilitate granulation, is adjusted to a mildly alkaline pH, and is adjusted to an ionic conductivity which will allow the sludge to mature rapidly when seeded with a beneficiating microbial flora. This process will reduce the pH of a high alkaline treated sludge, e.g., often above pH 12, to a physiological pH of between 7 and 9.5 or will raise the pH of a treated acid sludge to a similar range so that microbial activity can proceed to facilitate stability. Heat may be applied to the mixture to accelerate the carbonation and aid the overall drying process. The granular product, substantially due to its active microbial population, is useful as an agricultural product and topsoil blend.
Identifier(s): utpatents-US5275733 (IID)
Patent No.: US5275733 (patno)
Appl. No.: 07/839485 (appno)
Subject(s): 210/609
71/9
71/13
71/22
210/613
210/631
210/667
210/710
210/752
210/764
210/916
Held by: United States Patent and Trademark Office (USPTO) Public Search Facility
Location: University of Toledo Digital Repository
Rights Statement: No Copyright - United States
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