Pathogen reduction system used in treating wastewater
First Claim
1. A pre-digestion pathogen reduction system for treating sludge prior to the sludge being directed into a digester in a wastewater treatment system, comprising:
- a) an inlet for directing the incoming sludge into the system;
b) a series of reactors for receiving the incoming sludge as a series of batches, holding the batches of incoming sludge for a predetermined time to produce a pathogen-reduced sludge, and discharging the batches of treated sludge in a manner so as to form a continuous outflow of treated sludge to the digester, each reactor being operative to assume the feeding, holding, and discharge modes in sequence;
c) a sludge-to-sludge heat exchanger disposed on an inlet side of the reactors for receiving both the incoming sludge and the treated pathogen reduced sludge and transferring the heat associated with the treated sludge to the incoming sludge;
d) an outlet for directing the treated sludge from the reactors to the sludge-to-sludge heat exchanger prior to the sludge being directed to the digester such that as the treated sludge passes through the sludge-to-sludge heat exchanger, the heat associated therewith is transferred to the incoming sludge so as to heat the incoming sludge while at the same time cooling the treated sludge; and
e) at least one additional heat exchanger for cooling the treated sludge leaving the reactors, the additional heat exchanger being a wastewater effluent heat exchanger that is coupled to a source of wastewater effluent wherein the wastewater effluent effectively cools the treated sludge.
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Abstract
A pathogen reduction system for a sludge treatment process that employees multiple reactors operating in a batch mode to reduce pathogen levels in the sludge while providing a continuous flow of pathogen reduced sludge to a digester. In addition, the present invention entails an efficient heat exchanger for heating and cooling the sludge being treated in the above process. In particular, the heat exchanger is of the counterflow type and includes a helical coil confined in an annular chamber for transmitting one media and wherein the helical coil is spaced so as to form another helical flow channel that is defined by the annular chamber and the helical coil itself. Consequentially, one media is directed through the helical coil while another media is directed through the flow channel that is defined in part by the helical coil.
19 Citations
23 Claims
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1. A pre-digestion pathogen reduction system for treating sludge prior to the sludge being directed into a digester in a wastewater treatment system, comprising:
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a) an inlet for directing the incoming sludge into the system; b) a series of reactors for receiving the incoming sludge as a series of batches, holding the batches of incoming sludge for a predetermined time to produce a pathogen-reduced sludge, and discharging the batches of treated sludge in a manner so as to form a continuous outflow of treated sludge to the digester, each reactor being operative to assume the feeding, holding, and discharge modes in sequence; c) a sludge-to-sludge heat exchanger disposed on an inlet side of the reactors for receiving both the incoming sludge and the treated pathogen reduced sludge and transferring the heat associated with the treated sludge to the incoming sludge; d) an outlet for directing the treated sludge from the reactors to the sludge-to-sludge heat exchanger prior to the sludge being directed to the digester such that as the treated sludge passes through the sludge-to-sludge heat exchanger, the heat associated therewith is transferred to the incoming sludge so as to heat the incoming sludge while at the same time cooling the treated sludge; and e) at least one additional heat exchanger for cooling the treated sludge leaving the reactors, the additional heat exchanger being a wastewater effluent heat exchanger that is coupled to a source of wastewater effluent wherein the wastewater effluent effectively cools the treated sludge. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A system for reducing the pathogens in sludge comprising:
- a sludge inlet line;
a series of batch reactors connected to the sludge inlet line for receiving incoming sludge therefrom, the series of batch reactors disposed in parallel relationship and wherein during a selected treatment interval one reactor assumes a holding and treating mode and produces treated sludge while the other reactor assumes a discharge mode;
a series of heat exchangers for heating incoming sludge and cooling the treated sludge including at least one sludge-to-sludge heat exchanger operatively connected between the sludge inlet line and the series of reactors for heating incoming sludge passing in the inlet line and for cooling treated sludge leaving the reactors and wherein the sludge-to-sludge heat exchanger is connected to the inlet line such that incoming sludge passing through the inlet line is directed through the sludge-to-sludge heat exchanger before reaching the reactors; and
wherein the system includes an outlet line for directing treated sludge from the reactors back to and through the sludge-to-sludge heat exchanger such that the treated sludge passing from the outlet line back through the sludge-to-sludge heat exchanger acts to heat the incoming sludge while at the same time the treated sludge is cooled; and
a series of control valves disposed on inlet and outlet sides of the reactors and a programmable controller operatively connected to the control valves for controlling the same such that the individual reactors can be controlled to operate in a batch mode while the series of reactors as a group can be controlled to provide a continuous flow of sludge through the reactors. - View Dependent Claims (11, 12, 13, 14)
- a sludge inlet line;
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15. A method of treating sludge to reduce the pathogen concentration of the sludge comprising:
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a) heating incoming sludge by directing the incoming sludge into and through a sludge-to-sludge heat exchanger; b) directing the heated incoming sludge to a series of reactors; c) during one phase, holding the heated sludge within one reactor for a selected time period while discharging heated sludge from another reactor; d) during another phase, discharging the heated sludge from the one reactor while holding the sludge in the other reactor, thereby processing the heated sludge in batch form while providing a continuous outflow of treated sludge from the reactors; e) directing the treated sludge from the reactors back to the sludge-to-sludge heat exchanger and routing the treated sludge back through the sludge-to-sludge heat exchanger such that heat associated with the treated sludge heats the incoming sludge and in the process the heated sludge is cooled; f) further cooling the treated sludge by directing the treated sludge to a separate cooling heat exchanger; and g) directing treated wastewater effluent to the cooling heat exchanger and utilizing the treated effluent to cool the treated sludge after the treated sludge has exited the reactors. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23)
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Specification