US 9,169,147 B2Granted

Precision lime stabilization system and method for treatment of sewage sludge

AssigneeRDP Technologies, Inc.

InventorsRichard W. Christy, Michael Quici, Stephen H. Yost

Life of this patent

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Abstract

A lime stabilization system for treatment of sewage sludge, and method is provided in which dewatered sludge and lime are provided to a mixer. Lime and sludge are mixed to raise the pH during which volatiles are driven off with or without supplemental heat. A forced air draft prevents steam from backing up into the lime supply. The sludge goes to a discharge station via a transfer apparatus, and air containing any dust, odors, steam or ammonia is cleaned via a scrubber. The system is computer-controlled via gravimetric load cells and/or volumetric means. The system includes computer controlled means for dissolving scale resulting from exposure of surfaces to lime, using acid, water or combinations thereof.

Claims19

Dependent claims

A precision lime stabilization system for treatment of sewage sludge therein, comprising:

(a) means for increasing the solids concentration of the sludge;
(b) means for transferring the concentrated sludge to a sludge/lime mixer;
(c) means for supplying lime from a lime supply or from a means for feeding lime under controlled supplying conditions;
(d) means for feeding lime from the means for supplying lime to the sludge/lime mixer under any one of the following sequence conditions:
(i) after increasing the solids concentration of the sludge;
and
(ii) prior to increasing the solids concentration of the sludge;
(e) means for mixing the lime and sludge in the sludge/lime mixer to create a sludge/lime mix and to raise the pH of the sludge/lime mix to a range of about 10 to about 12.5;
(f) means for heating the sludge/lime mix to drive off volatiles from the mix;
(g) with the sludge/lime mixer being substantially enclosed;
(h) means providing a forced air draft to the sludge/lime mixer to prevent steam resulting from the means for heating the sludge/lime mix from backing up to the lime supply;
(i) means for transferring the sludge/lime mix from the sludge/lime mixer to a discharge station via a transfer apparatus;
(j) means for capturing air containing any of dust, odors, steam, ammonia and any combinations of any of them from the discharge station that result from the sludge treatment and for cleaning the air and discharging the cleaned air to atmosphere.

10 more elements

Dependencies are inferred from the claim text.

Facts

Application: 14/048,345Filed 8 Oct 2013 · continuation in part
Priority: 22 Nov 2011
Published: US 2014/0175026 A126 Jun 2014
Granted: 27 Oct 2015
Term ends: Not estimatedThe source records don’t support an estimate.

Classification6 codes

C02F 11/145
Using inorganic substances: using calcium compounds
C02F 1/529
By flocculation or precipitation of suspended impurities: processes or devices for preparing lime water
C02F 1/66
Treatment of water, waste water, or sewage: by neutralisation; pH adjustment
C02F 11/18
Treatment of sludge; Devices therefor: by thermal conditioning

Family

Application13/302,312Parent of this continuation-in-part · filed 22 Nov 2011
US 2014/0175026 A1Pre-grant publication · published 26 Jun 2014
US 2012/0061328 A1Published application
US 9,174,861 B2Related patent
US 9,169,147 B2This patent

From the US filing history. Foreign family members aren’t listed.