The Oculus™ System

Through the use of PLCs, HMIs, instrumentation, and programming based on our 30-year old installed base, the Oculus™ system reduces effluent ammonia, nitrate, total nitrogen, total phosphorus nutrients and energy usage in Carrousel® systems to the limits of technology. Effluent TN of <3 mg/L and effluent TP<0.3 mg/L without chemical addition is common.

Ovivo® developed the Oculus system predecessor, the ACE (Automated Control of Energy) system, as a simple way to control Excell® aerator speed to maintain an operator-desired dissolved oxygen set-point. Essentially, the aerator sped up when dissolved oxygen was too low, and slowed down when dissolved oxygen was too high. The newer Oculus System includes all the ACE System controls, but also allows for nutrient analyzer feedback to optimize ammonia and nitrate removal while minimizing energy input. Several different algorithms are available to the operator to vary aerator response, perfect for the operator who enjoys “tweeking” the process for optimum results. All options available to the operator are simple to control via a touch-screen interface.

 

The Oculus system also controls the EliminatIR® gate position based on ORP or nitrate probes installed in the anoxic zones. The Oculus System also controls effluent weirs, anoxic and anaerobic mixers, wall pumps—all equipment installed within the Carrousel® footprint.

 

The Oculus system is built with industry-standard programmable logic controllers (PLCs), Human Machine Interfaces (HMIs) and instrumentation (DO probes, etc). Trending screens are always included, which is useful for troubleshooting. Remote access and control from tablets and smartphones is also available, which puts the industry-leading Ovivo process support team at your fingertips.

How is power and oxygen input controlled?
There are two methods of controlling power and therefore oxygen input—impeller submergence and impeller speed.

Submergence: The water level can be lowered relative to the impeller by an effluent weir to reduce the “bite” on the impeller blades. The difference between the high water level (submergence) and low water level (submergence) is generally less than one foot (30 cm). In the past, this was the only method for controlling aerator HP output and oxygen delivery. Today, adjusting impeller submergence is performed with an electrically actuated weir to improve aerator transfer efficiency using our energy optimizer package, which is available with the Oculus control system.

Speed:  Variable frequency drives (VFDs) are commonly used today to adjust the impeller rotation speed. Reducing the rotational speed by half (e.g., 40 rpm to 20 rpm) reduces power input and proportionally oxygen input by 70-80%. Dissolved oxygen probes are typically used to determine the required speed of the aerator, and therefore HP input and oxygen delivery, at any given time.

Thus the combination of impeller submergence and speed adjustment can reduce power and oxygen input by 90%. Due to the lower turbine, the Excell® aerator can maintain mixing at these extreme power turndown conditions.

 

Do I need to control internal recycle?
For maximum nitrogen removal, yes. The internal recycle in a Carrousel System is free and is not limited by pumping capacity and can approach 15-20Q. While this high recycle rate is good for nitrate delivery to the anoxic zone, the large recycle can dilute the incoming BOD and anoxic zone detention times, suppressing overall nitrogen removal. A control system on the internal recycle allows you to have unlimited nitrate recycle capacity and allows you to make adjustments based on ORP measurements to deliver the optimum nitrate recycle at any given time.

 

Why is the Oculus™ system different?
The Oculus System is designed specifically for Carrousel Systems. Ovivo has developed specific algorithms based on our 700 installations to reduce nutrients and energy usage. You will not find the same flexibility and performance in any other system on the market.

 

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Carrousel® is a trademark of Royal Hasking DHV, B.V., the Netherlands.