Recycling activated sludge by hydrodynamic seperator (HDS) to enable high MLSS bioreactor to process high influent flow and/or high strength wastewater
View Patent ↗A wastewater treatment plant that employs an activated sludge process and a method of operating the same is described. Wastewater influent is provided to a bioreactor configured to perform activated sludge processing to develop mixed liquor suspended solids (MLSS). The MLSS is passed from the bioreactor to a hydrodynamic separator (HDS) system, where separation operations are performed on the MLSS. The separation operations generate a low concentration MLSS stream and a high concentration MLSS stream. The low concentration MLSS stream is passed from the hydrodynamic separator system via a first output to a clarifier, and the high concentration wastewater stream is passed via a second output back to the bioreactor. The clarifier performs clarification operations on the cleaned wastewater stream and then outputs an effluent flow.
1. A method of operating a wastewater treatment plant employing an activated sludge process (ASP), comprising:
providing wastewater influent, to a system of one or more bioreactors, either in series and/or in parallel, configured to perform activated sludge processing;
processing the wastewater within the one or more bioreactors to develop mixed liquor suspended solids (MLSS);
passing the MLSS in whole or in part from the one or more bioreactors to a hydrodynamic separator system;
performing separation operations on the MLSS within the hydrodynamic separator system, wherein the separation operations generate a low concentration MLSS stream and a high concentration MLSS stream;
passing the low concentration MLSS stream from the hydrodynamic separator system from a first output to a clarifier or clarifiers, and passing the high concentration MLSS stream from a second output back to the one or more bioreactors;
performing clarification operations on the low concentration MLSS stream from the hydrodynamic separator system in the clarifier; and
outputting an effluent flow from the clarifier or clarifiers; and
further including pulling the MLSS through the hydrodynamic separator system using two individual pump pulling actions provided by two separate pumps on two separate outputs of the hydrodynamic separator system.
2. The method according to claim 1 wherein the one or more bioreactors is configured to operate with a mixed liquor suspended solids concentration of approximately 4,500 mg/L or greater.
3. The method according to claim 1 wherein the one or more bioreactors is configured to operate with a mixed liquor suspended solids concentration of approximately 6,000 mg/L or greater.
4. The method according to claim 1 wherein the one or more bioreactors is configured to operate with a mixed liquor suspended solids concentration of approximately between 4,500 mg/L and 6,000 mg/L.
5. The method according to claim 1 , further comprising increasing treatment capacity of the ASP wastewater treatment plant by approximately 50% as compared to an identical system not including the hydrodynamic separator, wherein treatment capacity includes at least one of a flow rate or a mass loading rate of the wastewater influent.
6. The method according to claim 1 wherein the pulling actions are configured to provide two separately controllable flow rates, and to provide a MLSS split ratio through each of the first output and the second output.
7. The method according to claim 1 further including operating at least one of the pumps to flush at least one of the exits of the hydrodynamic system in at least one direction.
8. The method according to claim 1 wherein the pulling action prevents a break-up of MLSS flocs prior to processing by the hydrodynamic separator system.
9. The method of claim 1 wherein the wastewater influent is industrial wastewater.
10. A wastewater treatment arrangement comprising:
a bioreactor system having one or more bioreactors, either in series and/or in parallel, configured to perform activated sludge processing to develop mixed liquor suspended solids (MLSS);
a hydrodynamic separator system having an inlet to receive some or all of the MLSS processed by the bioreactor and configured to perform separation operations on the received MLSS, wherein the separation operations generate a low concentration MLSS stream and a high concentration MLSS stream, the hydrodynamic separator system further including a first outlet to pass the low concentration MLSS stream from the hydrodynamic separator system, and a second outlet to return the high concentration MLSS stream to the bioreactor;
an active pull flow control arrangement, including a first pump located at the first outlet of the hydrodynamic separator system and a second pump located at the second outlet of the hydrodynamic separator system; and
a clarifier having an inlet configured to receive the low concentration MLSS stream from the hydrodynamic separator system to perform MLSS separation on the low concentration MLSS stream and the clarifier further configured with an output to output an effluent flow.
11. The wastewater treatment arrangement of claim 10 wherein the bioreactor system is further configured to operate with a mixed liquor suspended solids concentration of approximately 4,500 mg/L or greater.
12. A method of operating a wastewater treatment plant employing an activated sludge process, comprising:
providing wastewater influent to a bioreactor configured to perform activated sludge processing;
processing the wastewater within the bioreactor to develop mixed liquor suspended solids (MLSS);
passing the MLSS in whole or in part from the bioreactor to a hydrodynamic separator system;
performing separation operations on the MLSS within the hydrodynamic separator system, wherein the separation operations generate a low concentration MLSS stream and a high concentration MLSS stream;
pulling the MLSS through the hydrodynamic separator by a pump pulling arrangement having a first pump at a first outlet of the hydrodynamic separator system and a second pump at a second outlet of the hydrodynamic separator system;
passing the low concentration MLSS stream from the hydrodynamic separator system from the first output to a clarifier, and passing the high concentration MLSS stream from the second output back to the bioreactor, wherein the clarifier is configured to perform MLSS separation via settling;
performing clarification operations on the low concentration MLSS stream from the hydrodynamic separator system in the clarifier; and
outputting an effluent flow from the clarifier.
13. The method according to claim 12 wherein the wastewater treatment plant is configured to operate at a mixed liquor suspended solids concentration of approximately 5,000 mg/L or greater.
14. The method according to claim 12 wherein the wastewater treatment plant is configured to operate at mixed liquor suspended solids concentration of approximately 6,000 mg/L or greater.
15. The method according to claim 12 wherein the wastewater treatment plant is configured to operate at a mixed liquor suspended solids concentration of approximately between 5,000 mg/L and 6,000 mg/L.
16. The method according to claim 12 wherein the pulling actions are configured to provide two separately controllable flow rates, and to provide a MLSS split ratio through each of the first output and the second output.
17. The method according to claim 12 further including operating at least one of the pumps to flush at least one of the exits of the hydrodynamic system in at least one direction.
18. The method of claim 12 wherein the wastewater influent is industrial wastewater.