Abstract: Systems for producing performic acid and methods for producing performic acid. The systems may include two or more reactor units, two or more servient programmable logic controllers, a control panel, and a master programmable logic controller. The system may modify the production of performic acid in at least one of the two or more reactor units upon and/or after the occurrence of a disruptive event in order to maintain a desired level of performic acid production and/or a desired level of disinfection.

Abstract: The invention relates to a method for cleaning a sensor in a wastewater monitoring arrangement comprising at least one sensor with a sensor surface, such as an optical sensor with a window, lens, or the like. In the monitoring arrangement, during a normal operation mode, a sample flow of wastewater is arranged to flow past the sensor surface and the sensor is arranged to provide measurement values that describe a quality parameter of the wastewater. The method comprising steps of: starting a sensor cleaning cycle by discontinuing the sample flow; starting a cleaning liquid flow; arranging the cleaning liquid flow towards the sensor surface; mechanically cleaning the sensor surface by an automatic cleaning device; discontinuing the cleaning liquid flow after a predetermined cleaning time and ending the cleaning cycle; and starting the wastewater flow again.

Abstract: Systems for producing performic acid and methods for producing performic acid. The systems may include two or more reactor units, two or more servient programmable logic controllers, a control panel, and a master programmable logic controller. The system may modify the production of performic acid in at least one of the two or more reactor units upon and/or after the occurrence of a disruptive event in order to maintain a desired level of performic acid production and/or a desired level of disinfection.