Small-scale clarification units are a crucial aspect for municipal wastewater removal concepts of the future. However, the only units permitted must have a biological treatment phase and the DIBt test mark (German Institute for Building Technology). Heinrich Bei der Kellen GmbH from Bramsche installed such a small-scale clarification unit for wastewater disposal from a listed, 250-year-old half-timbered farm house. The owner, with his own experience with different clarification systems for biological treatment, decided on an "Oxynaut" from Jung Pumpen.
Two adults and two children live on the 177 m2 ground floor of the former pay house, surrounded by 2,000 square metres of idyllic grounds. Approximately eight months were necessary to completely restore the building and adapt it to modern living and comfort requirements, taking into consideration specifications of the listed building authority.
Space and garden work saved
For the first time, builder Andreas Dröge relied on a small-scale clarification unit with full biological wastewater treatment through an "Oxynaut". "In my opinion, an ideal alternative to a three-chamber clarification unit with a connected organic bed. In this case, the large surface area required by such a bed, the extensive plant care necessary as well as the proximity of the plant bed to the house argued in favour of a SBR unit." Using the "Oxynaut" lifting pump, the biologically clarified wastewater is fed, over a low height difference, to a roadside ditch.
Heinrich Bei der Kellen, the company's managing director, also considers his builder's decision to be a forward-looking and intelligent choice. "We have recommended Oxynaut because we count on Jung Pumpen's product quality and, compared to other systems, the Oxynaut is particularly good to install. In addition, a small-scale clarification unit can be adapted to rising and sinking wastewater levels through simple adjustments to the Oxynaut. Important for maintenance: when operating, the unit is especially simple to handle and attains a high level of operating safety. On top of that, we know from experience that we can always rely on good support from Jung Pumpen's office and field service."
Variably adjusted to the number of people in the building
Responsibility for "Oxynaut" product management at Jung Pumpen lies with Jens Höwener who explains how adaptable a small-scale clarification unit with full biological treatment is when used with an "Oxynaut". "Due to the Oxynaut's numerous adjustment options, it can - taking into consideration the existing chamber volume - be optimally adapted to the requirements of a growing family." For this, the working volume of the activated sludge tank can be adjusted, based on the specifications from the building authorities and the number of connected inhabitants. This is especially important for small-scale clarification units which work on the SBR process since experience has shown that these units can always be best operated when high and stable volume loads for biological treatment are ensured.
For example, if a single family house in a rural area already has a three-chamber septic tank based on older dimensions - i.e. with 6 cubic metres total volume for four residents, this tank can be used for up to six residents, once changes have been authorised. The volume of the activated sludge tank is 1.5 cubic metres. However, for four residents - with the use of SBR technology - only 1.0 cubic metre is necessary and optimal for clarification processes. When retrofitting with an "Oxynaut", it is now possible to set the activated sludge tank to precisely this 1.0 cubic metre volume and also to adjust the exchange volume to the actual water consumption such that the clarification process is continual. For example, should two more people reside in the house in the future, these settings can be modified in 10 minutes during servicing.
"With these features, an installer can cater to changing requirements and not only by increasing aeration times which are often highly energy-consuming, as is normal with other systems." (Jens Höwener)
Maintenance with minimum effort
In the Osnabrück district, a trial system for self maintenance was implemented. That is, the clarification unit operator here was authorised - upon application - to carry out simplified maintenance without a water sample. To do so, the operator must be able to prove having received instructions from a certified maintenance company, such as Heinrich Bei der Kellen GmbH. In addition, professional maintenance including a water sample, is carried out annually by this specialist company.
Good water quality without special measures when putting the unit into service
The wastewater quality from the Dröge family clarification unit was shown to be remarkably good during the initial measurements, despite the fact that the unit had only been operating for a few weeks and had not been inoculated with activated sludge or otherwise modified when putting into service. After a short time, a COD value of 170 mg/l could already be measured (local limit value 150 mg/l). Bianca Bei der Kellen, the DWA certified specialist (German Association for Water, Wastewater and Waste) responsible for the maintenance of small-scale clarification units, is confident that by the first maintenance cycle in July 2005, a COD value significantly lower than 75 mg/l can be achieved.
Technology of the future: SBR
In recent years, the so-called SBR systems with submersible motorised aerators for small-scale clarification unit technology have become increasingly important. SBR stands for "Sequential Batch Reactor", which basically means that the oxygen is periodically added and mixed with wastewater.
The strictly biological treatment process, which is guaranteed through SBR technology, consists of four phases. Initially, the clarification unit is filled with wastewater to be treated and any excess sludge is removed. During the following aeration phase, the submersible motor aerator periodically adds air to the wastewater over a period of several hours. A so-called activated sludge forms on whose flakes microorganisms settle which break down the waste load of the wastewater. In a settling phase, this activated sludge separates from the clarified water and sinks to the bottom of the tank. In the final phase, a clarified water pump feeds the treated water into the discharge or irrigation system. The wastewater treated in this way can seep away, unrestricted, on the property or be discharged into public bodies of water.
"Oxynaut" for existing and new small-scale clarification units
The new SBR system from Jung Pumpen combines the reliability of well-known submersible motors and lifting pumps (produced in Steinhagen, Germany) with the benefits of this modern clarification technology. The SBR system can be fitted into existing units for restructuring and provides a reliable service as the central system component for fully biological small-scale clarification plants for 4 to 12 inhabitants.
By combining state-of-the-art technologies, the best possible biological clarification is attained. The submersible motorised aerator, which was specially developed for the "Oxynaut", swirls ultra-fine air bubbles into the wastewater and thus creates the ideal conditions for the clarification process. The aerator is not fixed so that it can adjust to the water level within the chamber. This way, the optimum submersion level is ensured - and the "Oxynaut" reaches a biological clarification performance of up to 99 percent.
Convincing in performance and installation
The "Oxynaut" is ready-to-plug-in and can be immediately used without a great deal of effort. Thanks to its compact and modular construction, it is simple to install. Since all external aggregates have been eliminated, the unit exhibits extremely low noise levels when in operation and its optimal power consumption pays off economically. The DIN and DIBt tested system is the most economical unit in its class.
In April 1984, master mason Heinrich Bei der Kellen founded a building business and planning office. Today, 10 employees and 2 apprentices work for Heinrich Bei der Kellen GmbH. Based on a good mix of old and new technologies in the building industry, the entrepreneur tries to ensure the highest level in building quality. For more than 10 years, he has relied on wastewater technology from Jung Pumpen.
In a few minutes, the "Oxynaut" can be adjusted for changing numbers of residents and wastewater quantities from a household.