Small wastewater treatment plant

System KLARO One

The fully ventilated. A single-stage, fully biological treatment plant based on the SBR process with aerobic simultaneous sludge stabilization. Sludge storage and buffer are integrated.

The KLARO One system has been on the market since 2015 and is enjoying growing popularity. The "One" is particularly suitable for small plant sizes (4, 6, 8 PE), private households and sensitive locations.

The system does not require any preliminary clarification. The inflowing wastewater is immediately subjected to aerobic treatment.

Fields of application

  • Up to 600 EW or 90 m³/d ( further information about the plant sizes)
  • All types of waste water
  • Complete system, retrofit

Advantages and features

of the KLARO One System

  • No risk of concrete corrosion
  • Separation of waste water and technology

  • Air pump instead of submersible pump

  • Retrofit kit made of waste water resistant plastic / installation parts made of waste water resistant stainless steel

  • No risk of decay odor
  • Stable procedure against shock loads and underload
  • Stable cleaning performance even in winter
  • High operational reliability
  • Mature technology - on the market since 2015 - in use worldwide
  • No tight partition wall required
  • Independent of container material and geometry

  • Wide range of process customization options via the control system

  • Sludge stabilization and mineralization, no digestion

  • Very low sludge accumulation and thus low desludging frequency

  • Low maintenance - no sludge measurement in primary clarification necessary

  • Low energy consumption through fine bubble ventilation

  • User-friendly, because of automatic operation

The KLARO One SBR-cycle


1. Aeration phase

The raw wastewater first reaches the front section of the plant and is immediately subjected to aerobic treatment. Membrane aerators at the bottom ensure aeration of the entire tank volume. The required compressed air is generated by an air compressor, which is installed in an external control cabinet. The aeration is usually intermittent. This aeration causes:
• The microorganisms of the activated sludge are supplied with oxygen, which is necessary for their metabolic activity and thus for the decomposition of the pollutants, an intensive contact between waste water and bacteria is created
• Mineralization of the sludge

2. Sedimentation phase

During the 120-minute settling phase there is no ventilation. The activated sludge can sediment. A layer of sludge forms at the bottom and a clear water zone in the upper area. Inflowing raw sewage is retained in the front area.

3. Clearwater extraction

A compressed air hoist in the rear of the unit removes part of the clear water from the tank. The special construction of the siphon
• Prevents the pumping off of any floating sludge on the clear water layer
• Minimizes the unwanted penetration of activated sludge into the siphon during the aeration phase by means of an inlet slope
• Ensures that a desired minimum water level is maintained in the system without additional components

KLARO One Process Film

In the animated film opposite, the three phases of the KLARO One SBR process and the most important components of the small sewage treatment plant are explained once again.

Cleaning performance

The KLARO One system achieves excellent effluent values, comparable to municipal sewage treatment plants. This is confirmed by the results of tests and the thousands of plants in operation worldwide, which are regularly maintained and checked.
The system has been intensively tested in practice at the PIA testing institute according to EN 12566-3.

Effluent values

Wastewater parameterEffluent valuesEfficiency
COD48 mg/l94,2 %
BOD57 mg/l96,0 %
NH4-N0,5 mg/l96,3 %
Ntot7,9 mg/l87,0 %

1,6 mg/l

96,3 %

SS14 mg/l96,3 %








Results of the practical test according to EN12566-3

  • Very good cleaning performance
  • Outstanding nitrification and denitrification
  • Stable effluent values
  • Trouble-free operation
  • Low power consumption
  • Particularly low sludge generation demonstrated (sludge disposal frequency "zero")

In addition, several voluntary "hardness tests" were run:

  • Sludge growth
  • Bathtub joint
  • Desludging and restarting

The certified reliability

In order to avoid sludge drift, we have introduced patented siphon solutions for our KLARO and KLARO ONE systems.
In addition to improving the lifters, correct dimensioning - as KLARO does - is also important. This ensures that impact loads such as external inlet peaks are easily compensated.
As a model for such a siphon, for example, take two simultaneous bathtub drains (400 L emptied in 3 minutes).

For the KLARO ONE system we have decided to do an extra test.
The purpose of this test was to prove that even under extreme hydraulic peak loads there is no unwanted flushing of sludge from the system. For this purpose, 400 l of water were added within 3 minutes at the test field of a 5 PE plant operated under full load (simulation of two emptied bathtubs simultaneously). Thanks to the special design of our drain lifters, the water in the drain remained clean - during the peak inflow and also during the pumping process afterwards.
We want to show that our ONE systems also work with hydraulic spikes.

The result is impressive: PIA-certificate
Process and dimensioning of the KLARO One lead to perfect function and avoid undesired operating problems such as sludge drift - now also certified by PIA.

Quality since 20 years

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