Increased Treatment Security, Process Optimization Through Improved Monitoring Techniques

Recent implementation of the Long Term 1 Enhanced Surface Water Treatment Rule (LT1ESWTR) has increased potable water sampling and analysis requirements for an additional 11,000 treatment plants serving more than 18 million Americans.

Filtered systems must comply with strengthened combined filter effluent turbidity performance requirements to assure 2-log removal of cryptosporidium. Conventional and direct filtration systems must continuously monitor turbidity of individual filters and comply with follow-up activities based on this monitoring.

Maintaining optimum coagulant dosage in surface water treatment is a critical part of achieving filtered water quality. The streaming current monitor (SCM) has become the standard technology for optimizing coagulant dosage. The streaming current monitor measures electrokinetic charge of the dosed water, and provides operators with continuous monitoring and coagulant control.

Alarms are initiated if the “optimized” streaming current value exceeds high and

low limits. This is paramount in avoiding major process upsets, and causing turbidity excursions.

Although the LT1ESWTR is based on turbidity monitoring, it has been well documented that particle counters and particle monitors provide a level of particulate detection far above nephelometric turbidimeters for particles in the crypto size range (3-10 microns). This is a function of basic light physics (light scattering vs. light extinction). Many plants are installing particle counter/monitors as an “early warning” against turbidity excursions and potential EPA violations.

The events of September 11, 2001 have added another meaning to “ensuring water quality.” It is imperative that the in-plant treatment process not be compromised. Some plants are not manned 24/7, or are understaffed. Therefore, sensitive, reliable on-line devices must be used to detect process failures or upsets. This data must be immediately available to all responsible parties, or the process must be shut down.

To meet this need, the streaming current monitor, turbidity and particle count data has been integrated into a JAVA based system using a standard Web browser call WebTRAC™. This system provides process data to password designated, remote locations via telephone line or the Internet.

This means that the operator, plant superintendent, police department, or other party assigned a password can know if critical plant processes are functioning properly. If not, alarms can be activated.

A unique feature of the WebTRAC system is that interfacing does not require a dedicated personal computer or proprietary software. All the process control, inputs, outputs, and data collection are done by the system’s Web Access Controller (W.A.C.).

The information can be accessed by designated personnel via a Web browser connected through the phone or network connection to the W.A.C. Video cameras also can be included in WebTRAC to provide site monitoring and security.

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About the author

Robert L. Bryant is the president of Chemtrac Systems, Inc. located in Norcross, GA.