US 11,453,608 B2 · Method for pre-conditioning sludge

Abstract

Sludge, for example primary sludge or waste activated sludge or both from a wastewater treatment plant, is pre-treated prior to anaerobic digestion. The pre-treatment includes an optional mechanical treatment to reduce the viscosity of the sludge and a biological hydrolysis treatment. The biological hydrolysis treatment may be performed in a series of reactors some of which are maintained at a temperature in the range of 50 to 70° C. The reactors provide a combined residence time in the range of 0.5 to 6 days. Optionally, measurements of the pH of the sludge during or after biological hydrolysis, or the production of biogas from a downstream anaerobic digester, may be considered in adjusting the temperature of one or more of the biological hydrolysis reactors.

Claims17

Dependent claims

A method for pre-treating a wastewater treatment plant (WWTP) sludge comprising waste activated sludge before anaerobic digestion, the method comprising the steps of:

initially maintaining the WWTP sludge comprising waste activated sludge under anaerobic conditions at a temperature in the range of 55 to 62° C. for a period of between 0.5 and 3 days and subsequently maintaining the WWTP sludge comprising waste activated sludge under anaerobic conditions at a temperature in the range of 35 to 70° C. for a period of between 0.5 and 3 days;
or,
maintaining the WWTP sludge comprising waste activated sludge under anaerobic conditions at a temperature in the range of 35 to 70° C. for a period of between 1 and 6 days including holding the WWTP sludge comprising waste activated sludge within the period at a temperature of at least 55° C. for 24 hours or more.

Dependencies are inferred from the claim text.

Method for pre-conditioning sludge

Life of this patent

Method for pre-conditioning sludge

Life of this patent

Abstract

Claims17