Abstract: A self-compensating fluid level sensor is described, including a dual array of capacitive sensors on a dielectric substrate, the dual array of sensors forming multiple sensor pairs. Multiple signal detection circuits including comparators are configured to compare the capacitance of a first sensor pair with a second sensor pair. The internal capacitance comparisons allow the fluid level sensor to compensate for variations in the dielectric of the fluid being measured, as well as for manufacturing and materials variations that affect capacitive sensing. The passive level sensor also provides a platform for providing additional circuitry for providing additional information regarding the liquid, such as liquid composition.

Abstract: A wastewater treatment system substantially reduces wastewater treatment time and increases treatment capacity. The system includes at least one completely covered aerobic reactor cell and a completely covered quiescent anaerobic reactor cell. The system can also include a polishing reactor for further treating wastewater after treatment by the anaerobic reactor cell. The covered aerobic reactor cell preferably includes a pair of subcells in which a first cell includes continuous mixing and aeration of the wastewater and the second cell includes only intermittent mixing and aeration of the treated wastewater. The system optionally includes a completely covered anoxic reactor cell for treating wastewater prior to treatment by the completely covered aerobic reactor cell. The anoxic reactor cell receives partially treated wastewater recirculated from the polishing reactor. Growth media can be used in the reactor cells to enhance biological activity.

Abstract: A wastewater treatment system substantially reduces wastewater treatment time and increases treatment capacity. The system includes at least one completely covered aerobic reactor cell and a completely covered quiescent anaerobic reactor cell. The system can also include a polishing reactor for further treating wastewater after treatment by the anaerobic reactor cell. The covered aerobic reactor cell preferably includes a pair of subcells in which a first cell includes continuous mixing and aeration of the wastewater and the second cell includes only intermittent mixing and aeration of the treated wastewater. The sytem optionally includes a completely covered anoxic reactor cell for treating wastewater prior to treatment by the completely covered aerobic reactor cell. The anoxic reactor cell receives partially treated wastewater recirculated from the polishing reactor.