Glossary

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Bioreactor / SBR tank

In a fully biological small wastewater treatment plant, a bioreactor (SB reactor) is installed downstream of the mechanical pre-treatment. The actual biological purification takes place in the SBR tank. Short aeration and rest phases alternate in a controlled purification process.

BOD₅

The biochemical oxygen demand after 5 days indicates the amount of oxygen required within 5 days to biologically (by microorganisms) break down the organic substances present in the wastewater. The specification of the value results from the Waste Water Ordinance.

COD

The chemical oxygen demand indicates the amount of oxygen required to break down all organic substances present in the wastewater - including non-biodegradable substances. The specification of the value results from the Wastewater Ordinance.

Commercial wastewater

This includes industrial wastewater from manufacturing companies, restaurants, etc.

DIBt

The German Institute for Building Technology in Berlin is responsible for issuing general building inspectorate approvals for small wastewater treatment plants, which are a prerequisite for the installation and operation of small wastewater treatment plants.

DIN EN 12566

Deutsches Institut für Normung e.V. EN 12566 is a European standard for small wastewater treatment plants up to 50 PE. It consists of a total of seven parts, some of which are still being worked on.

DIN 4261

DIN 4261 is a German residual standard consisting of two parts. This standard contains detailed provisions (application, dimensioning, operation, maintenance, etc.) for small wastewater treatment plants.

Domestic wastewater

All wastewater from private households that flows into a small wastewater treatment plant.

Effluent class

The performance of small wastewater treatment plants is divided into different discharge classes, which are specified by the German Institute for Building Technology. A general distinction is made between the effluent classes C, N, D, +P, +H. The individual effluent classes can be varied. C = carbon degradation N and D = additional nitrogen degradation +P = additional phosphate reduction +H = additional hygienization.

Excess sludge

Excess sludge is the excess activated sludge that continuously accumulates during the activated sludge process.

Hygienization

After the degradation of carrion and nutrients, the aim is increasingly to hygienize the wastewater in order to eliminate pathogens in the biologically treated wastewater. This involves irradiating the biologically treated wastewater with UVC light, for example. As a result, the wastewater treated in small wastewater treatment plants achieves a better water quality, which in turn allows it to be discharged into sensitive areas (karst or water protection areas).

Multi-chamber septic tanks

Multi-chamber septic tanks are the original method of wastewater treatment. A multi-chamber septic tank usually consists of two to three chambers, which effectively retain the solids content. Multi-chamber septic tanks usually have a size of 0.3 m³/E (minimum volume 3 m³) and must be emptied at least once a year. Multi-chamber septic tanks with a size of 1.5 m³/E (minimum volume 6 m³) are classified as biological sewage treatment plants. Multi-chamber septic tanks cannot meet today's requirements and must therefore be upgraded to small biological sewage treatment plants.

Monolithic container

The container is made from one piece. The counterpart to this in a concrete tank is, for example, the ring construction method. The advantage of monolithic tanks is that they have good stability and are watertight.

Nitrogen reduction

Elimination of the nitrogen contained in sewage water. Nitrogen is broken down biologically with the help of certain strains of microorganisms. Plants with additional nitrification use particularly intensive aeration to create optimum living conditions for nitrifying bacteria, which convert ammonium (NH4) into nitrate (NO3). In systems that are also designed for additional denitrification, short aeration bursts at the start of the aeration phase are used to circulate the water and stimulate the denitrifying bacteria, which convert nitrate (NO3) into elemental nitrogen (N2).

Population equivalents (PE) Calculation for residential buildings

Small sewage treatment plants for residential buildings are to be dimensioned according to the number of inhabitants.

• At least four PE per residential unit >60 m2
• At least two PE per residential unit <60 m2
• In the case of a combination of more than three residential units or buildings (group solutions), these minimum requirements may be waived for these additional residential units.

Post-clarification

Last stage of the wastewater treatment plant. The sludge carried along settles in this stage before the purified water leaves the plant. In SBR plants, the secondary clarifier is omitted. Settling takes place directly in the activated sludge or SBR tank.

Pre-treatment

The aim of pre-treatment is to separate coarse matter from the wastewater by gravity. This means that the wastewater is pre-cleaned. Pre-treatment relieves the downstream biological stage.

Primary sludge

Solid components of wastewater that settle in the first chamber of a small wastewater treatment plant.

Rainwater

Rainwater must not be fed into the small wastewater treatment plant. Diluting the wastewater has a negative impact on the cleaning effect. It can also overload the system hydraulically.

Ring construction method

Concrete tanks can be erected on site using the ring construction method. This involves gluing ring after ring on top of each other until the desired tank size is reached. The advantage is that transportation is easier. The disadvantage is that the tightness between the individual rings can deteriorate.

Sewage sludge

The solids produced during mechanical and/or biological wastewater treatment by sedimentation (deposition due to gravity).

Small wastewater treatment plants

Wherever a connection to the sewer system is not economically feasible, small wastewater treatment plants are installed. Small wastewater treatment plants are systems for the treatment of domestic wastewater collected in the separation process with a daily wastewater volume of up to 8 m3.
The following may not be discharged:

• Commercial and agricultural wastewater (insofar as it is not comparable with domestic wastewater)

• Condensates from fireplaces with pH values below 6.5 substances that interfere with sewage treatment plant operation

• Drainage water from swimming pools

• Extraneous and cooling water

• Rainwater

State Water Act

As the Water Resources Act (WHG) was merely a framework law until March 1, 2010, all further details that went beyond the framework legislation were regulated in the LWGs of the individual federal states. This situation has changed since the WHG was converted into a full law and the state water acts can now only decide on deviations to a limited extent or make use of so-called opening clauses.

Switch cabinet

The switch cabinet is the head of our small wastewater treatment plant. It contains the control unit, the compressor, the solenoid valves, but also the additional components, such as the phosphate pump or the modem for remote monitoring. A distinction is made between outdoor switch cabinets (installed outdoors) and indoor switch cabinets (installed in a building, house or cabin).

Testing according to EN12566-3

This is the standard test procedure for small wastewater treatment plants in Europe. An original wastewater treatment plant is installed at a testing institute and put through its paces with real wastewater over a period of at least 38 weeks. Samples are constantly taken from the inlet and outlet. This very realistic test also looks at how the plant behaves during the start-up phase, in the event of overload and underload, in the event of faults such as a 24-hour power failure, temporary loss of inflow (vacation), etc. Power consumption and sludge accumulation are also documented. The most important results are summarized in the test certificate. The test certificates are also recognized in many countries outside Europe.
The first test of a KLARO-SBR small wastewater treatment plant was carried out in 2000/2001. Over the years, the plant has been continuously technically improved and retested. Plants with additional treatment stages such as P-precipitation or hygienization (wastewater disinfection) also had to be tested separately. Our systems have always performed very well in all tests.
Click here for the current test certificate of the KLARO system.
If you would like to find out more about other test results, please contact us.

Underload

Underload is a frequently discussed topic for small wastewater treatment plants. Some types of plants have difficulties complying with the discharge values if the inflow volumes or loads fluctuate. However, this is often the case in practice! Back in 2011, we subjected the KLARO plant to a voluntary endurance test to demonstrate that our plant copes well with various underload scenarios that go beyond the normal test program. The system was operated over several weeks with various low loads (50%, 25%, 0%).  The discharge values hardly deviated from those in nominal operation and were always well below the usual limit values.

Walkable / Driveable

With a cone (cover), a distinction is made between walkable (5 tons) and drivable. In the case of drivable, there is a further differentiation between 12.5to. (passenger car) and 40to. (TRUCK). Depending on the positioning of your small wastewater treatment plant, you must choose between walkable or drivable.

Wastewater ordinance

The discharge of wastewater into bodies of water is subject to various requirements that are regulated in the Wastewater Ordinance. In the area of small wastewater treatment plants, the Wastewater Ordinance regulates the limit values, which are defined in more detail within the discharge classes.

Wastewater treatment plants

From 50 PE to 10,000 PE, they are referred to as wastewater treatment plants. Plants for population equivalents of less than 50 are small wastewater treatment plants.

Water law permit

A permit from city and state authorities (e.g. lower water authority) authorizing the discharge of treated wastewater into surface waters or groundwater.