Our customer ISV Umwelt UG has equipped the sewage treatment plant Felsberg, a town in the North Hessian region of Schwalm-Eder, about 20 kilometers South of Kassel, with a new centrifuge for sludge dewatering. SPANGLER supplied the control and automation technology for this project.

The dewatering centrifuge

The centrifuge is fed with a mixture of thin sludge to be dewatered and flocculant previously prepared in a dosing station. Due to the high speed and the resulting centrifugal force in the centrifuge, the suspension is separated. Because of the higher density, the solid particles collect on the outer wall of the drum and the less dense liquid in the center of the centrifuge. The discharge screw inside the centrifuge drum rotates at a higher speed and thus conveys the settled particles to the solids discharge. The liquid drains off at the opposite side.

With Spangler towards Industry 4.0

For an optimum dewatering result a precise regulation of the quantity ratio between thin sludge and flocculant is necessary. The flow sensors and further sensors required for this are connected via the IO-link to the Siemens PLC (S7-1215C). The IO-Link devices can be centrally parameterized via the TIA portal and diagnostic information can be read out. In case IO-link devices are exchanged, the previous configuration is transferred automatically to the new sensor. Thus, standstill times can be minimized and the personnel expenses can be reduced.

For monitoring and display purposes, current machine data are transferred via a bus interface via S7 protocols to the on-site control system. The plant is operated via a touch panel TP1200 which is installed in the control cabinet front. For the remote access operation, the user interface via Sm@rt-Service can be transferred to an internet-enabled end device (e.g. laptop, mobile phone, tablet, …). A LTE modem enables access both from the specially created local W-LAN network and via VPN from the internet. The VPN-tunnel enables ISV Umwelt UG and Spangler to access the system remotely to offer for example service support or to install program updates. Furthermore, to save costs, the remote access was used to carry out the start-up.

The water treatment system of our customer Bertschi AG in Switzerland actually works perfectly after the tank has been cleaned. The water added with chemical substances is treated and can therefore flow back into the sewer system. However, most components, including the control units, are outdated. So, it was time to bring the plant up to the latest technical standard so that the process can continue to run smoothly in the future, according to the customer’s statement. Spangler Automation was then commissioned to modernize the water treatment plant with the Retrofit-Service.

Demanding process of water treatment

With the cleaning of the tanks, chemical substances are added to the water. Therefore, it must not be returned to the sewer system without prior treatment. During treatment it passes through various areas, one of them is the treatment in the supply container. Here, the waste water pre-treated by the reaction tank is gradually fed into five supply tanks, aired and the sediment deposited on the bottom is removed. In the next step the waste water flows into so-called aeration tanks in the biology area. Here, urea, defoamer and phosphoric acid is added manually for the correct pH-value. Afterwards the pretreated waste water flows into the two ultra filtration streets and is pumped through the filtration circle for cleaning and filtering. The filtered waste water flows into the permeated tank. After previous fine treatment, the water is now clean and can flow back into the sewer system.

Extensive retrofit of the control technology

In agreement with the customer, a functional specification sheet of the plant process was established. Thanks to the detailed pre-planning the visualization and programming could be implemented smoothly. The special aspect about this order was the short-term and simultaneous application of two PLCs running in parallel in one plant. It was possible to switch between both controls. This made it possible to switch to a new redundant control system quickly and safely. Before the final conversion to the new PLC was concluded, the plant was tested intensively in advance with the help of a remote simulation. After the first test run, it was already possible to switch from the old control system to the new one. Two Siemens PLC S7-1500-R and one ET200SP as decentral periphery were applied. Additionally, two Siemens operation devices HMI TP1500 were installed.

Pondus® Verfahrenstechnik GmbH has commissioned Spangler Automation to install a new disintegration plant in the sewage treatment plant Erlangen. This is a process for the digestion of microorganisms in sewage sludge, the so-called thermal-chemical cell disintegration. Due to a preliminary project, many parallels could be drawn, and the project could therefore be implemented relatively quickly.

Thermal-chemical cell disintegration

With the process of thermal-chemical cell disintegration (hydrolysis) sewage sludge is heated up in a special reactor and with the addition of base, the cell membrane is broken down to the greatest possible extent. In this way, the organic residual material in the digested sludge is reduced and dewatering is improved. The dry proportion of the dewatered sludge is increased and the amount of sewage sludge that must be disposed is reduced. The residual heat included in the sludge after heating is re-used in the following process steps such as digestion.

Versatile automation and control technology

Spangler Automation has planned, produced and programmed the automation technology for this system. Three control panels were equipped with the central Siemens PLC S7-1516. In addition, the plant was connected to the control system that can be operated locally. With the Siemens IPC477E 22 inch a clear layout was created and enables intuitive working at the plant. The coupling of the three control panel fields was implemented with the decentral interface module ET200SP. The multifunctional Siemens measuring instrument PAC3220 is used for the energy analysis; power and voltage values are online available. The continuous and equal feed of the plant technology is guaranteed by pumps, controlled by two frequency conformers.

Spangler Kids Day – a great initiative that provided a unique insight into the working world of parents for the youngest members of the families.

Spangler decided to take over the care of their employees’ children for half a day because of the school holiday, on which the parents had to fulfill their professional duties. The Spangler Kids Day took already place in the past and was not only initiated to offer a special event for kids during a holiday, but for the children to get to know the working places of their parents in a relaxed atmosphere.

Success factor family

With the Kids Day, the management of Spangler stresses its strong commitment for the compatibility of work and family, which has already earned them an award as a family-friendly company from the Federal Ministry for Family Affairs, Senior Citizens, Women and Youth.  The event offers the children the opportunity to experience their parents from a new perspective and shows the strong focus on appreciation of the family by the company.

The day started with a warm welcome of the children, a group picture and an amusing introduction game to get to know each other. Then the motivated kids prepared a healthy breakfast together with the Spangler team.  In this way, the day started with fun and a sense of community.

The highlight – save use of electricity

The highlight of the day was definitely the fascinating experiments with self-made battery cardboard figures. Two apprentices, who are currently doing an apprenticeship to become an electronic technician in automation and systems technology, instructed the kids and explained the experiments.

As in real working life, the findings were checked and then recorded. This practical learning emphasizes Spangler’s commitment to support the training, especially in the natural scientific field.

Inspiring future experts

The Spangler Kids Day ended with another highlight, when the kids visited their parents‘ workplaces and gained a first insight into their daily working lives. This initiative stresses Spangler‘s goal, not only to show the parents their appreciation, but also introduce the children to the possible workplace of tomorrow.