Varying water level solids and tracking control
A sequencing batch reactor includes a liquid level sensor configured to measure a level of liquid in the vessel and provide an indication of the level of the liquid to a controller and a sludge detector configured to measure a position of an interface between sludge and solids-lean supernatant in the vessel and to provide an indication of the position of the interface to the controller. The controller is configured to perform a comparison between the level of the liquid and the position of the interface and control an amount of solids-lean supernatant removed from the vessel during the decant stage based on the comparison.
1. A method of controlling a wastewater treatment system, the method comprising:
introducing a volume of wastewater into a sequencing batch reactor vessel of the wastewater treatment system;
biologically treating the wastewater in the vessel;
maintaining quiescent conditions in the vessel sufficient for solids in the wastewater to settle and form a blanket of settled sludge and a solids-lean supernatant;
measuring a level of liquid in the vessel;
providing an indication of the level of the liquid to a controller;
measuring a position of an interface between the blanket of settled sludge and the solids-lean supernatant in the vessel, the position of the interface measured by a sensor that moves vertically in response to a change in the level of the liquid in the vessel;
providing an indication of the position of the interface to the controller;
performing a comparison between the level of the liquid and the position of the interface with the controller;
decanting the solids-lean supernatant from the vessel; and
controlling an amount of the solids-lean supernatant decanted from the vessel based on the comparison.
2. The method of claim 1 , further comprising introducing the wastewater into the vessel at a non-predetermined rate.
3. The method of claim 1 , further comprising:
determining a degree of sharpness of the interface; and
providing an indication of the degree of sharpness of the interface to the controller.
4. The method of claim 3 , further comprising initiating decanting of the solids-lean supernatant responsive to the degree of sharpness of the interface exceeding a predetermined level.
5. The method of claim 3 , further comprising varying a speed of decanting of the solids-lean supernatant based at least in part on the degree of sharpness of the interface.
6. The method of claim 3 , further comprising controlling a rate of sludge removal from the vessel based at least in part on the degree of sharpness of the interface.
7. The method of claim 1 , further comprising controlling an amount of sludge removed from the vessel based at least in part on the position of the interface.
8. The method of claim 1 , wherein introducing the volume of wastewater into the vessel includes introducing a non-predetermined volume of wastewater into the vessel.
9. The method of claim 1 , further comprising controlling a rate of decanting of solids-lean supernatant from the sequencing batch reactor vessel to maintain a substantially constant depth of solids-lean supernatant above the interface during settling of the sludge.
10. The method of claim 1 , wherein the sensor is configured to float on the liquid in the vessel.