With conclusion of the Paris Agreement, specific goals were defined for the protection of the climate and the environment. To reach these goals, the federal and state governments offer communities and private individuals a broad range of supportive subsidies and measures to help them renovate and modernise buildings and plants. The goal of the measures is to reduce CO2 emissions and to promote sustainability and environmental protection through conceptual and financial support.
The target group for the subsidies includes operators of wastewater treatment plants. After all, wastewater technology is an industry in which a relatively large amount of energy is invested and therefore has immense potential for savings. Wastewater treatment plants are among the biggest energy consumers in a community. The main reason they use so much energy is because they have to generate compressed air.
That air plays an important part in aerating what are termed aeration tanks (the ‘biology’ of the plant). It is introduced to the tanks at a pressure of approx. 1.5 bar and serves to enrich the wastewater with oxygen. Oxygen enrichment is an important step in biological sewage treatment. The requisite volume flow is generated by compressors: Depending on the type of plant, the solution may rely on positive displacement blowers, turbo blowers, screw compressors, rotary lobe compressors, or a combination of machines.
It naturally takes a lot of energy to compress air or gases using screws or rotary pistons. It is a thermodynamic process, in which a great deal of electrical energy is converted into heat energy. On the one hand, the medium is heated up, and on the other, heat is generated from the radiation of the motors under the acoustic hood. In the past, the resulting potential often went unused and the heat was simply released outside. Today, however, there are many options for making sensible use of this heat energy (also known as waste heat) for subsequent processes in the wastewater treatment plant. AERZEN offers many different grant-worthy concepts and possible solutions for refurbishing, renovating, or expanding existing plants.
The high level of energy consumed when compressed air is generated is only natural and says little about the quality of the compressors that are used. But because each machine runs at peak efficiency under different requirements and conditions, it is crucial to choose exactly the right blower technology for the application and to use an automated, optimised control system for the machines that compress the air. With the right expertise, it is possible to greatly reduce energy consumption and CO2 emissions by choosing the ‘right’ blower or compressor. What’s more, an automatic control system such as AERsmart can adjust the volume flow to the actual oxygen requirements in the aeration tanks at all times. This prevents excess energy from being generated. The installation of new, demand-driven machines for energy conservation is one of many optimisation measures that AERZEN offers its customers.
Many wastewater treatment plants require renovation and optimisation from an energy standpoint. There are many options for improving efficiency that also help protect the environment by making more efficient use of energy resources. They range from changing the combination of machines and automating compressed air generation to optimising machine rooms and recovering energy. These possibilities are not always easy to recognise. Special measurements and data collection are often required, and not every operator can do it alone.
When designing new plants, a sustainable, forward-looking concept is absolutely crucial, because the right expertise can lead to huge savings over many years of operation. As a global market leader in the field of wastewater management, AERZEN offers cutting-edge concepts in this area.
Modernisation measures of this kind are not only energy-saving and inexpensive for the consumer, but also beneficial for the environment, in that having energy-efficient machines in the factory reduces CO2 emissions. The federal government rewards this achievement with financial support and funding programmes.
A decisive factor for low-cost, environmentally friendly energy use in wastewater treatment plants is the selection of a custom-fit compressor technology capable of generating a volume flow based on demand. Compressed air generation accounts for up to 80% of a plant’s total energy costs.
Every wastewater treatment plant is subject to fluctuations that are based on the season and time of day and have to handled flexibly. That’s why it’s important to examine what loads a plant deals with over the year and what control range has to be covered. Only then can a reasonable decision be made about which machines should be used.
When deciding, keep in mind that every compressor technology may entail certain advantages and disadvantages, depending on the type of application, or may be optimised for specific use cases.
Positive displacement blowers, for example, are relatively inexpensive and ideally suited for large control ranges. The smaller turbo blowers are more efficient when the control range is more limited and the speed more constant. A hybrid blower combines the positive characteristics of both technologies.
For larger wastewater treatment plants with a higher workload and large fluctuations, it may make sense to use a combination of different machine technologies. AERZEN provides an ideal solution for this scenario with its Performance³ concept. A group of machines with an integrated, intelligent control system can reliably cover any differences in demand that may arise. Depending on the workload of the wastewater treatment plant, the most efficient machine or combination of machines is deployed to generate the volume flow for oxygen enrichment.
Even the most efficient machine group can still be optimised from an energy standpoint, because a significant amount of process heat is generated for purely physical reasons by the air compressors during the compression process. Some of the heat is generated when the air is compressed by screws or rotary pistons, and some is caused by the heated exhaust air from the motors under the acoustic hood.
AERZEN has developed highly efficient methods for utilising this process heat. For example, a heat exchanger can be integrated behind the compressor. This converts the energy and makes it available for subsequent processes. Another option for heat recovery is to make direct use of the hot exhaust air from the compressors via a piping system to heat service water, to dry workpieces or to generate hot water for showers and washrooms. Waste heat that would otherwise be released outside is reused in a way that conserves energy. Both methods of recovering energy are eligible for federal subsidies that are made available to municipalities.
Positive displacement blowers, turbo blowers, compressors and frequency converters generate high temperatures in the machine room that negatively impact the service life of the machines. AERZEN offers its customers efficiently sized aeration systems for controlling the climate of the machine room. Soundproofing optimisations are also available.
Among the broad range of funding programmes and financial grants aimed at accelerating environmental protection, a distinction can be made between concept funding and investment funding. Here are two examples:
As a manufacturer of energy-efficient air compressors and a specialist in heat recovery, AERZEN can assist its customers with valuable advice in both cases and greatly simplify the application process for precisely tailored funding. The family-owned company provides support by, for example, analysing existing plant or compiling the data required for the investment measures in advance. If funding programmes for pilot projects are being applied for, AEZREN draws up the relevant blueprints.
Questions like these are complicated and can only be answered by specialists. Technical details have to be clarified in advance and data has to be collected and made available. All this takes time, and plant operators don’t always have it. The service provided by AERZEN offers customers decisive advantages, because the dialogue with the compressed-air specialists creates synergies that can substantially reduce how much effort customers have to put into applying for funding.
In the process, AERZEN always focuses on individual, customer-specific requirements. It also provides ready-made testing and analysis concepts. With AERaudit, for example, which was developed in-house for energy optimisation, it is possible to determine what energy conservation options would result from the use of a custom-fit machine group and exactly how much it would reduce CO2 emissions.
In order to optimise its services in the area of subsidies, AERZEN has cooperated with the federally funded e.qua network to put together a community of interest consisting of representatives from water management, science and politics. e.qua deals with issues of energy efficiency, energy recovery and resource management. The cooperation between AERZEN and e.qua has created additional significant benefits for AERZEN customers.
AERZEN does the measuring. For example, it measures the actual volume flow requirement or calculates the CO2 emissions. Using AERaudit, AERZEN evaluates the existing performance data on the plant, generates energy analyses and implements energy optimisations by selecting positive displacement blowers, turbo blowers or screw compressors to form an optimal machine concept.
In addition, AERZEN provides support in the form of concepts for heat recovery, including graphic representations of the amount of energy recovered and the calculated reduction in CO2 emissions. For machine room optimisation, AERZEN offers its customers concepts for room ventilation and noise reduction.
e.qua provides support for eligibility verification and preliminary clarification of suitable funding options for energy concepts and evaluates whether investment subsidies can be applied for. It is also possible to contact project sponsors and to obtain help with funding applications via e.qua.
Whether for designing a new, efficient plant or renovating an existing one, AERZEN customers can count in both cases on the available financial support. Entirely in the spirit of sustainable wastewater management.
PAGES IN THE TOPIC WORLD WASTE WATER TREATMENT:Water and wastewater treatment | Performances for wastewater treatment plant operators | Case studies | Performance³ | Wastewater treatment guide | Performance Calculator