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Water Purification

The project consisted in the implantation of an ADEX control system to the biological purification phase of the water treatment plant of Ceutí, Murcia (Spain). In this project, two ponds were controlled working in parallel.

The biological process of the water treatment plant at Ceutí works in carousel operation. Each pond has diffusers through which air is injected to oxygenate the water. The necessary air is injected with one or more blowers with a frequency inverter, through a common pond collector. There are valves controlling the air flow rates in each pond

The operation process mode is cyclic. Each cycle consists of two phases: nitrification and de-nitrification. During nitrification phase, aerobic bacteria oxidize the ammonia dissolved in the water converting it to nitrites and afterwards to nitrates. The second part of the process is de-nitrification. Here, the treatment is anaerobic, where the oxidized forms of nitrogen are converted to less noxious forms.

The biological purification requires a large amount of energy due to the electricity consumption of the blower, so the objective is to minimize this energy cost, maintaining an acceptable quality level of treated water.

By working with ADEX control system, energy consumption decreased by 30%.

Legend of trend curves:

  • Green lines represent the dissolved oxygen in water of two ponds
  • Yellow lines represent the redox potential of two ponds (limits are defined with dark blue lines)
  • Dark blue lines represents the performance range upper and lower.
  • Blue line represents frequency (Hz) of blower
  • Red line represents the pressure of common collector
  • White and gray lines represent percentage opening of valves at each pond
  • The highlighted lines represent Pond 1 and the others represent Pond 2.

Manual Control System

The blower is running at 50Hz (maximum power) all the time in the nitrification phase of the cycle.

The two ponds are evolving in a different way because the same air is supplied to each pond, and the bacteria are of different ages.

ADEX Control System

The ADEX control system controls the power of the blower and at the same time the oxygen rate in the treated water, through a setpoint in ramp, where the oxygen rate adapts it through the appropriate valve in each pond.

The blower is running at 35Hz (minimum power) most of the time in the nitrification cycle, saving 30% of energy.

Water quality is improved because the two ponds are evolving in the same way.

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