FAQs – Frequently Asked Questions


The term small wastewater treatment plants defines plants for the cleaning of domestic wastewater up to an amount of wastewater of 8 m³/d. With 150 litres per person, this corresponds to approx. 53 persons. The classification is made in habitants/persons with the abbreviation PE. The smallest plant is 4 PE small wastewater treatment plant.

Partly biological is the partly removal of unsolved pollutants, e.g. conventional sceptic tanks reach by means of mechanical removal (settling) a cleaning performance of approx. 30 %. Multi chamber tanks do not longer comply with the state-of-the-art and have to be retrofitted with a fully biological kit.

Fully biological goes beyond that and removes by means of microorganisms even most of the solved pollutants. The cleaning performance regarding carbon degradation should not be below 90 %.

Fully biological small wastewater treatment plants are used, where the treatment in a central wastewater treatment plant is not possible. They reach the same cleaning performance as central wastewater treatment plants.

The performance capability of small wastewater treatment plants is divided in five different filtration levels that among other things require different maintenance frequencies. Most commonly is the standard requirement, filtration level C, thus carbon degradation. Only in certain cases, e.g. in drinking water protection zones, a higher filtration level is required. The responsible authority has more information about that.
We have the following classification:

  • C (carbon degradation)
  • N (nitrification)
  • D (denitrification)
  • +P (phosphate elimination)
  • +H (hygienization)

Service, maintenance & inspection

The self-inspection (performed by the operator) refers essentially to visual and acoustic inspection and is described in the user guide installation and operation. As a rule, daily and monthly visual inspections are described. This is comparable to the inspection at a car (gas, water, oil, air, etc.).

With the klärofix there is also a remote monitoring devise available. The operator inspections can be omitted.

A specialised company or the manufacturer performs the maintenance. It hast to take place once, twice or three times a year. The frequency depends on the rules and regulations of the depending country.

Apart from exceptions in urban centres (privatization), this is imposed on the community by the legislators.
Generally, this depends on the respective country.

Ask the responsible authorities, how to handle this situation.

There is no general answer to this question. Sludge occurs through different user behaviour. Food leftovers also increase the amount of the primary sludge significantly.

The maintenance technician should let you know, when a sludge removal is necessary. In the course of a maintenance the sludge level should be measured.

Control technology and technical equipment

A fully biological small wastewater treatment plant generally consists of a mechanical (sceptic tank) and a biological part (reactor).

The individual technical installation parts are customary parts and also used in other industries. Generally, every cleaning system is only as reliable as its individual technical parts. Determined by the system, with the klärofix we can dispense with electrical pumps and other moving parts in the wastewater.
The only consumer is the air compressor that has to be installed outside the tank in a dry place. When operated properly, the lifetime of all parts is many times higher as with parts that have to be installed in the wastewater.
As one of the first manufacturers of small wastewater treatment plants, the utp umwelttechnik pöhnl strictly commits to the principles of “Design for Recycling (DfR)”. You can find the recycling passport for our small wastewater treatment plants.

Are all parts connected (inlet and outlet pipes, connecting pipes to the control unit), the operator has to fill the plant with water (all chambers). Afterwards the power supply will be established (plug into socket). The control unit starts with a short control phase and will then go into operation automatically.

You do not have to make any settings on the klärofix. The plant will run automatically.

There are substantial differences between the manufacturers and the wastewater treatment types.
The utp small wastewater treatment plants are equipped with a low-maintenance and energy-saving air compressor. utp plants run load-dependent, i.e. the less wastewater occurs, the less is the energy consumption. (The plants do have a power-save-mode).

Operation and range of application

A wastewater treatment plant may not be fed with rainwater, drainage water, cooling water, liquid waste materials, chemicals, paint residues, medication, fats, oils, acids, lyes, slurry, manure and silage effluents.

Rainwater may not be fed into the small wastewater treatment plant at all because it would be overloaded immediately. Furthermore, the reactor will be rinsed due to the overload of rainwater. Rainwater needs to percolate or led to a receiving water.

After the treatment, the cleaned wastewater has to be returned to its natural water cycle. If possible, this should happen by means of adequate running waters.
If there is no suitable receiving water, it can be percolated in the underground.