MFA Control of Turbidity
of Water Treatment Process
|• Automatically controls water Turbidity
during changes in water quality, feed rate, seasons,
||• Smoother operations, more consistent water
quality, and higher yield.
MFA controller can handle large process
time delays in a range of 1 to 2 hours, or longer.
||• Avoids over-dosing or under-dosing of
|• Improves water quality and reduces chemical
||• Better standard of living and good ROI.
Water Turbidity Real-Time Automatic Control Solution
Quality: The U.S. Environmental Protection
Agency (EPA) requires that all municipal water utilities
conduct a daily test for turbidity. Turbidity particles
harbor harmful contaminants like viruses and bacteria.
Turbidity is the key water quality variable, which is
typically measured in Nephelometric Turbidity Units
Process: In order to become acceptable
for public use, raw water in a water treatment plant
must go through mixing, coagulation, sedimentation,
filtration, and disinfection processes. Coagulation
removes suspended dirt and other particles from water.
Alum, Aluminum Sulfate Al2(SO4)3, and other chemicals
are added to form tiny sticky particles called "floc"
which attract the dirt particles. The combined weight
of the dirt and floc become heavy enough to sink to
the bottom during sedimentation. Water turbidity is
directly related to the contents in the raw water and
the amount of Alum added.
Problem: Online monitoring and control
of turbidity is desirable. Although turbidity sensors
are available, automatic control of turbidity has been
an industry-wide problem. The extremely long delay time
between adding Alum to the time when turbidity is finally
measured at the end of the sedimentation process is
the "killer" of an automatic control system.
Solution: CyboSoft now offers an innovative
Model-Free Adaptive (MFA) control solution for controlling
turbidity without having to build process models and
retune controller parameters.
Case Study: For an international city
like Shanghai with 12 million residents and 3 million
visitors, the improvement of water quality has had a
strategic impact on the standard of living and economy.
Since 2002, Shanghai Water Treatment plant has deployed
an MFA control system and achieved great results. Turbidity
has been controlled consistently within 3.5+/-1 NTU
even with large variations in raw water contents. The
trend above shows Turbidity is under tight control.