Mini-analyzers monitor sulfite and chlorine levels

Problem: The wastewater plants in Clarkson and Guelph, Ontario, use chlorine disinfection but have severe chlorine residual limits because the receiving stream has sensitive aquatic life. The usual approach is to feed sulfite to dechlorinate the effluent, but sulfite is an oxygen scavenger, and large residuals can result in reduced dissolved oxygen in the stream, replacing one problem with another.

Solution: Two ChemScan mini-analyzers from ASA Analytics monitor sulfite/chlorine levels and address the feed control issue. A mini LowChlor chlorine analyzer with a detection limit of 0.005 mg/L monitors the chlorine residual before or after sulfite feed, and a mini sulfite analyzer with a detection limit of 0.01 mg/L monitors the sulfite residual. The combination provides a suite of analysis that allows both chlorine and sulfite to be minimized in the effluent.

Result: The plants have performed extensive pilot testing of the system, documenting success in replacing ORP-based control. 262/717-9500; www.asaanalytics.com

Related: Advances in Monitoring and Instrumentation

Continuous online monitoring system helps facility solve staffing issue

Problem: In South Charleston, Ohio, the water resource recovery facility is staffed by a part-time contract operator. To keep up with new permit requirements, the village faced a doubling of staff hours.

Solution: Instead of increasing the number of staff hours, the operator installed a continuous monitoring system: the IQ SensorNet System from YSI, a Xylem brand, online sensor network for continuous monitoring and process control. Measured values are output to a third-party cellular telemetry unit that allows real-time measurements to be viewed online. Alarms programmed into the telemetry unit notify the operator of potential problems.

Result: “The purpose for the installation was to maintain the same amount of hours required for the plant operator to be on site,” says Steve Canter, project consultant. “The YSI IQ SensorNet System provides continuous monitoring of effluent DO, pH and turbidity in addition to influent and effluent flow monitoring that can be remotely monitored to activate predefined alarm and relay setpoints.” 800/765-4974; www.ysi.com

Related: How We Do It: Scanning Success

Tank covers address WWTP odor concerns

The grit tank covers that Geomembrane Technologies Inc. provided at the Georgetown Wastewater Treatment Plant have successfully minimized odors.

When houses were developed within a few hundred feet of the plant’s property line, it wasn’t long before new residents complained about odors. Plant management made a public commitment to address the problem, and focused on its grit tanks. “We were convinced capturing and treating odors was the way to go,” says Wendy Derjugin, plant operations supervisor at the plant.

GTI was selected to custom-design and install structurally supported covers for the grit tanks.

Related: Monitoring and Instrumentation

The covers easily retract, meeting the plant’s access requirements. Captured foul air is then withdrawn and treated in a carbon system. “Covering the grit tanks was one of the most effective things we could do to further reduce the potential for odors,” says Derjugin.

Read the full story at www.gticovers.com or call 855/484-4630.


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