Turbidity Monitoring Improves Water Treatment

Turbidity monitoring is an essential measurement technique for improving water quality and reducing environmental damage. It is a critical part of the efficient management of water treatment, both within a treatment plant and in the receiving waters.

Global Water has pioneered the development of a submersible turbidity sensor that does not require a flow-thru chamber. The WQ710 is the heart of the company's Series 700 system. The 710 sensor is a microprocessor-based optical device enclosed in a water tight housing. It uses an incandescent light source and a photo detector that measures reflected light at 90 degrees.

The sensor is a true nephelometer which conforms to the EPA approved Method 180.1 for turbidity monitoring in drinking water. In addition, the WQ710 provides pulsed light technology, which reduces power requirements and corrects for light intensity/color changes and optical window fouling.

The sensor is available in four ranges, with an industry standard 4-20 mA output signal for direct connection to all PLCs, controllers, dataloggers and process control/SCADA systems. The sensor does not require a flow-thru chamber or local display/controller under usual conditions.

Monitoring of combined filter effluent is critical to safe water treatment, so the Series 700 turbidity monitoring system combines the WQ710 sensor, the Global Flow-Thru Chamber and the Global Display/Controller, for final-water monitoring and control. The system offers a local readout in NTU; two set points for local or remote alarms; and an isolated 4-20 mA output for interface with existing process control systems. A datalogger option provides a permanent record of final effluent turbidity and automatic compliance report generation.

For filter-bed monitoring, the WQ710 sensor can be placed directly into the filter water and connected to existing process control systems or to the Global Controller. A flow-thru chamber and a pumping system are usually not required. This provides considerable reduction in cost and maintenance, as well as faster response to filter problems.

The new federal regulations will require that each filter bed be monitored continuously while maintaining turbidity levels at 0.3 NTU or lower. The Series 700 with datalogger option is ideal for recording and automatically reporting this massive amount of data.

For backwash monitoring and control, the WQ710 can be mounted directly into the backwash line or in a bypass line flow-thru chamber.

Monitoring of the raw influent water is essential to efficient plant operation. The Series 700 can be used for continuous monitoring, or the WQ770 portable meter can be used to spot check raw water quality.

The WQ770 portable meter is also useful for monitoring programs to reduce reservoir and river turbidity upstream of the treatment plant, which ultimately improves treated water quality. The portable unit also can be used to monitor runoff from construction sites, agriculture runoff and storm drains, as well as wastewater treatment plant effluent.

Global Water manufactures a complete line of instrumentation including level, flow, water quality, weather, remote monitoring and control. Its catalog with specifications, manuals and pricing can be found at www.globalw.com.