Resource efficiency in the wastewater treatment plant

Water is our most important natural resource: It is clear that without clean water diseases spread particularly quickly. Wastewater treatment plants not only make an important contribution to protecting this resource, but are also a key to greater sustainability.

With resource efficiency to climate neutrality.

Washing, brushing one's teeth, drinking – everyone needs clean water, and the more people live on this earth, the higher the demand. Climate change, urbanization and increasing environmental pollution are aggravating the situation. The protection of this number one resource is becoming increasingly urgent. Wastewater treatment plants make an important contribution here. Not only do they treat wastewater and discharge it back into our waters, but they also serve as energy storage facilities, flexible energy consumers and generators, and thus make an important contribution to the energy transition and sustainable water management.

Digestion towers for the extraction of methane from sludge

Nuremberg is leading the way: Resource efficiency in the wastewater treatment plant

Sustainable wastewater treatment and energy supply is becoming increasingly relevant, especially in cities. This is also the case in Nuremberg. The Franconian metropolis has set itself big goals: By 2035, the city's municipal government is to become climate-neutral. Stadtentwässerung und Umweltanalytik Nürnberg (SUN) has a key role to play here: With its two large-scale wastewater treatment plants, it is the largest single consumer and the largest producer of electricity. Therefore, the topic of resource efficiency is an important component for achieving greater sustainability. A key role here is played by Wastewater Treatment Plant 1, which elaborately cleans the majority of the wastewater from more than 500,000 inhabitants of the metropolis mechanically, biologically and chemically before the treated water is discharged into the Pegnitz River. Matthias Germeroth has a great view from the roof of one of the five 35-meter-high digestion towers. But that's not why he comes here often. As energy manager at Stadtentwässerung und Umweltanalytik Nürnberg (SUN), Matthias Germeroth's tasks include optimizing the energy consumption of the facilities in the area of urban drainage and environmental analysis – and the wastewater plant's digestion towers are an important component in this.

The largest producer – and the largest consumer of energy

From the digested sludge that is processed in the towers, the wastewater treatment plant extracts methane, which is converted into electricity and heat in a total of four combined heat and power plants. This is one of many measures with which SUN is making its contribution to greater sustainability, explains Britta Walthelm. As the City of Nuremberg's Environment and Health Officer, she is also the first plant manager of SUN: "The Nuremberg City Council has decided that the municipal administration of the city of Nuremberg should be climate-neutral by 2035." SUN performs two roles in this process, according to Germeroth: "We have a sewer network stretching more than 1,500 kilometers that transports wastewater to us at the wastewater treatment plants, and more than 100 outdoor structures. With the two large-scale wastewater treatment plants, we treat over 1.3 million population equivalents, making us the largest single consumer, but also the largest generator of electricity. That's what makes it very compelling."

Matthias Germeroth and a young man looking at a tablet together, standing in front of control panels

Due to rising energy costs, we are naturally very interested in optimizing our processes as much as possible.

Volker Nachtmann, Technical Plant Manager, Stadtentwässerung und Umweltanalytik Nürnberg

Making interconnected material and energy flows visible

"Only through resource transparency can we use resources efficiently and flexibly," explains Volker Nachtmann, Technical Plant Manager at Stadtentwässerung und Umweltanalytik Nürnberg. For this purpose, the energy management system records gasoline, natural gas and diesel consumption, electricity consumption, and consumption values for heating and cooling. On the generation side, the heat and cold produced and the electricity generated, broken down by the energy sources sewage gas, fossil fuels for the emergency power generators and photovoltaics, are included in the balance. In this way, the system permits SUN to analyze consumption and generation and thus tap potential for improvements, according to Germeroth: "We now have the opportunity to showcase energy efficiency potential that has previously gone undiscovered."

A really striking revelation was that we can partially supply Wastewater Treatment Plant 1 with 100% self-generated energy.

Matthias Germeroth, Energy Manager, Stadtentwässerung und Umweltanalytik Nürnberg

Good for the climate and the balance

The technical basis for this was implemented by SUN together with Siemens: SIMATIC Energy Manager Pro makes energy consumption and material flows transparent and supports both the operating level and various company divisions and the entire SUN with automatic reporting and monitoring. For this purpose, the system records up to 800 data points from around 500 energy meters as well as from the process and building control systems. For Germeroth, this flexibility is one of the great strengths of this solution: "With SIMATIC Energy Manager Pro, we have the possibility to bundle the enormous amounts of data and bring them together into meaningful quantities: The administrative buildings, the laboratories, cooling generation, cooling consumption, compressed air and sludge quantities, fill levels, sewage gas quantities, but also the vehicle fleet. A really striking revelation was that there are already many phases in which Wastewater Treatment Plant 1 is supplied with 100% self-generated energy." Volker Nachtmann adds: "Due to rising energy costs, we are naturally very interested in optimizing our processes." Part of these considerations is to merge the city's two large-scale wastewater treatment plants – and the energy management system can also provide important key figures for this.

Resource efficiency is climate and nature protection

Energy efficiency, more in-house generation, more renewable energy sources – for Matthias Germeroth, these goals are much more than just key figures. From the digestion towers, he also looks down on the Pegnitz River, which flows from Nuremberg toward Fürth. Together with the rivers Rednitz and Regnitz, it constitutes a valuable natural area, which in the densely urbanized region is at the same time a recreational area, a source of water, and a natural air-conditioning system. But rising temperatures and more erratic rainfall are causing problems for rivers. So nature protection is not possible without climate protection – and this requires greater efficiency in energy use. Britta Walthelm therefore has a clear stance: "Energy management is useful, indispensable, and easier than you think. The kilowatt hour that I don't use is the one that is best. The message: Just get started."

The control room with multiple monitors and desks as well as a big dashboard on the wall

Digestion towers for the extraction of methane from sludge

With its operations, Stadtentwässerung und Umweltanalytik Nürnberg (SUN) makes a decisive contribution to protecting the environment and maintaining the wuality of life in the Nuremberg metropolitan area. SUN is not only responsible for collecting and purifying Nuremberg's wastewater, but also monitors water quality in the Pegnitz, Rednitz and Regnitz rivers. It also measures and evaluates environmental pollution in the areas of water, air, and soil.