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
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