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03/2016. Focus on WASTE WATER. Event calendar May / June 2016 News from VDI and VDE 50 years of IFAT Munich Satellite Navigation Summit


1 B 2883 News from technology, science and economy 03/2016 MAY / JUNE The regional magazine for VDI and VDE with a focus on WASTE WATER Event calendar May / June 2016 News from VDI and VDE 50 years of IFAT Munich Satellite Navigation Summit

2 CONTENTS Innovative. Worldwide. Future-oriented. Experience environmental technologies. Register online now! May 3rd June 2016 World's leading trade fair for water, sewage, waste and raw materials management Discover the possibilities of future-oriented strategies, products and services. Be there when the world's leading trade fair for environmental technologies presents complex processes and applications of machines, systems and vehicles in a clear and practical way in spectacular live demonstrations. Welcome to IFAT IFAT Worldwide Visit IFAT's international trade fairs: May September February September Follow us: 2 MESSE MÜNCHEN Tel Technik in Bayern 01/2010

3 EDITORIAL Out of sight out of mind? Photo: R. Maier Silvia Stettmayer Editor TiB This expression very aptly reflects our relationship with waste products of all kinds and especially with wastewater. What you can no longer see, you forget. And in this case, only too gladly. Admittedly, the topic is not particularly pleasant, but both the history and the technology behind modern (waste) water management are fascinating. To know what we're talking about, let's first take a look back: The Romans already recognized the importance of sewers, the most famous building is the Cloaca Maxima in Rome. The aqueducts were connected to the sewer system, the constantly flowing water washed away the garbage and also protected the sewer system from clogging. The principle was simple and ingenious, unfortunately this knowledge was lost in the Middle Ages. The conditions in the cities of Europe must be up to the 19th century. into it would have been almost unimaginable, they were sewers stinking to heaven. Due to the strong increase in population, there were repeated cholera epidemics, which regularly killed many thousands. Bacteria and viruses were still unknown, so it was believed that bad smells were the miasms to be responsible for spreading disease. An infernal stench The Big Stink in the hot summer of 1858 was the decisive factor for civil engineer Joseph Bazalgette to build a sewage network for London at the time, the largest city in the world with almost four million inhabitants. This sewer system is still in operation today, and the Munich sewer system, initiated by doctor and hygienist Max von Pettenkofer, has existed for more than 130 years. These great institutions, which brought clean drinking water to many people in Europe and created a healthier livelihood, are undoubtedly a cornerstone for subsequent social and economic development. It is therefore not surprising that today China and India are making large investments in water management for their billions of people. Typically, often with technology from Europe. Many German companies are also among the world market leaders with their sophisticated system technology. And it is no coincidence that the world's leading trade fair for water, sewage, waste and raw materials management, IFAT, is celebrating its 50th anniversary this year. Taken together, we are in an enviable position. If we continue to develop our water management at this technically high level and ensure that highly qualified specialists will continue to look after this complex world under our feet in the future, we can continue to lean back with a clear conscience when it comes to wastewater and say: Out of sight out of mind. 3

4 CONTENTS 6 Photo: S. Stettmayer Focus Everyone benefits from environmental investments 6 Interview with Prof. Martin Grambow Technology in municipal wastewater treatment 10 Konrad Koch, Brigitte Helmreich, Jörg E. Drewes wastewater networks must be maintained 11 F. Wolfgang Günthert Economic climate protection in sewage treatment plants 12 Kai Christensen and Werner Weigl The largest solar sewage sludge drying facility in southern Germany 14 André Großer Efficient oxygen input in aeration basins 16 Ute Klausner Optimized secondary clarifiers 17 Dieter Hilligardt Max von Pettenkofer A sewer system for 19 The historical background of Florian Breitsameter 1 Photo: University of the Bundeswehr 12 Photo: BBI Bauer Beratende Ingenieure GmbH Cover picture The historic sewer system of Prague around 1900 Photo: Chalabala, Fotolia 4

5 CONTENTS University and Research University: Wastewater Technology: Research Project Schlakavi 22 Daniela Hansjakob News VDI BV: General Assembly VDE Südbayern: General Assembly VDI Bayern Nordost: General Assembly Electromobility Day 27 Munich Satellite Navigation Summit 36 ​​Digital Personnel File Already fit for the future? VDI / VDE students and young engineers 28 VDI regional association: Maker garages 29 Bavarian meetings of students and young engineers 30 VDInis visit Audi in Ingolstadt 31 Formula Student Team Strohm and Sons 33 VDE Südbayern: Reactivate senior citizens 34 VDI Bayern Nordost: Technology mile 35 VDI Prize 2016 : Apply now 35 VDE-AK Corporate Management 46 We cordially invite you to our free live presentations. Your physical well-being is also taken care of. Sections Calendar of events 39 Book reviews 48 Exhibition tip 50 Preview 50 Imprint 50 Register now! VDI Regional Association Bavaria VDI District Association, Upper and Lower Bavaria e.v. Westendstrasse 199, D Tel .: (0 89), Fax: (0 89) VDI Bezirksverein Bayern Nordost e.v. c / o Ohm University, Keßlerplatz 12, D Nuremberg Tel .: (09 11), Fax: (09 11) VDE Bavaria, District Association South Bavaria e.v. Hohenlindener Straße 1, D Tel .: (0 89), Fax: (0 89) The next appointments, noon, noon Free registration for MuP Medien Gruppe Nymphenburger Str.20b Tel .:

6 FOCUS We all benefit from environmental investments The highest state authority for matters relating to water management is the Department of Water Management and Soil Protection of the Bavarian State Ministry for the Environment and Consumer Protection (StMUV). The Bavarian State Office for the Environment (LfU), the seven district governments and the 17 water management offices are subordinate to the StMUV. We spoke to department head Prof. Dr.-Ing. Martin Grambow on the wastewater situation in Bavaria and the ministry's tasks. TiB: As a water management authority, you support the Bavarian municipalities in the tasks that result from the obligation to dispose of wastewater. Can you briefly outline these tasks? Prof. Grambow: In the state part, water management is divided between the Free State of Bavaria, which has management discretion, i.e. manages the water supplies, and the municipalities, which, according to the Water Act, are responsible for taking care of the water infrastructure, i.e. water supply and wastewater. So we have to do with the municipalities in a multiple function; On the one hand, we give the reports on which the water law permits are based. Another very large part of our work is advising municipalities and we also give funding within the framework of the grant programs. So we have an advisory and a promoting role, but also a demanding role in terms of the conditions and introductory values. TiB: Requirements with regard to the law? Grambov: Exactly. We have a very clever system for treating wastewater. This is a combined approach, a mixture of the immission and emission principle. The emission principle means that everyone who discharges wastewater has to meet certain minimum legal requirements. In addition, we take a look at the water itself as part of the immission principle. Where there are special requirements, for example in very small or already polluted bodies of water, we also require stricter standards, because our focus is on keeping the bodies of water clean. TiB: Are we pioneers in Europe? Grambow: With Max Pettenkofer, Bavaria naturally has a historically significant figure 6 in research into wastewater and there are world-leading companies in wastewater technology here. Last but not least, the organization of the IFAT trade fair (see info box) is also a figurehead. And Germany is a pioneer in Europe because we started working on this wastewater sector very early on. But most of the rules apply across Europe. TiB: Are there a lot of specifications coming from Brussels? Grambov: Yes, and to be very clear: these regulations are sensible and important. And it is good that they apply to all EU countries, because otherwise, for supposed economic reasons, similar to tax law, there would be competition within the EU countries. In this respect, this EU law is ingenious because it sets a standard that everyone must meet. And we all benefit from it. In my opinion, the cost side is always emphasized far too much here, wastewater as a cost factor. In a nutshell, this is nonsense, because water supply and wastewater treatment in general, keeping the environment in order is, first and foremost, an essential part of our safety and quality of life. TiB: Of course wastewater is a cost factor, but doesn't modern wastewater technology also create real added value? Grambov: Of course! Time and again it is said that the environmental requirements would put a strain on the economy, but that is simply not true. Everything has to be developed and produced, sold and bought. This creates many jobs. The only difference from traditional investments is that we all benefit from environmental investments, not just a few. The contribution to the quality of life through this water infrastructure is greater than through many other things for which we otherwise spend a lot, a lot of money. TiB: If we now look out from Europe into the world, how would you assess the situation? Grambow: Germany is already a trendsetter here, so to speak. For example, when I tell my colleagues from India what we do in wastewater treatment and drinking water supply, I often hear that you are a rich country and that is why you can afford to invest in this infrastructure. But beware! Maybe it's the other way around: because we invested there early on, we're doing well today. It is my deep conviction that at least part of our success is based on the fact that we take care of such things successfully and thus create an environment in which we can work and live successfully. TiB: You were just talking about India. What about China, the other state with more than a billion inhabitants? Grambow: Both in India e.g. With the Clean Ganges project as well as in China, the projects are increasingly being taken up because the bright minds in these countries know intuitively that they have no alternative at all. Because if these large countries India and China do not get their water infrastructure under control very quickly, they will run into gigantic problems. China invests billions. We don't even notice it here, but wastewater treatment plants are being built everywhere. It is also interesting that China in particular continues to buy technology from Europe. Europe stands for quality and wastewater technology is an export hit. TiB: India and China are emerging countries with areas of high technology. How is it in Africa? Grambov: There are contacts and aspirations here too, but Africa is difficult and the main problem is poor governance.

7 FOCUS TiB: How could the situation be improved worldwide? Grambow: Of course there are also cultural differences, but an important point is that we in Europe can think about such problems and tackle them accordingly. But the most important thing is the very first understanding that environmental investments are not an obstacle to the economy, but rather a condition, and that is what sets us apart. And what's more, we want that because it's part of our culture. This attitude should be much more prevalent. Of course, there are always these relapse tendencies that it would be much cheaper, e.g. in agriculture to get the last 2-3% increase in yield and therefore to drown the landscape in nitrate. This is of course cheaper at first, but only for this one moment. It is a misfortune for all future generations. We can only counteract these excesses by constantly providing information and reminding people of what the Isar looked like 30/40 years ago, for example, and what it looks like today, there are no mountains of foam and it does not stink. TiB: But 40 years is a long way. Grambov: Yes, but here we come back to the EU. In 1976, exactly 40 years ago, the first EU water protection directive for the retention of dangerous substances from wastewater was passed. It was one of the first issues that the EU took up across the board. Cartoon: Cornelis Jettke Photos: Silvia Stettmayer 7

8 FOCUS TiB: Who is responsible for these technical solutions? Grambow: The municipalities do that themselves. The employees work fantastic, there are thousands of people here with excellent training, for whom the whole world also envies us. And rightly so! From the sewage master to the utility engineer, we have people at every level who know exactly what they are doing. I would like to emphasize that it is anything but trivial to maintain these networks. If you simply imagine these underground structures as a 3D diagram, then it becomes clear that these are extremely complex, complicated, but also fascinating facilities. TiB: Keyword Isar: In the past, the sewage treatment plants were flooded during heavy rain and then bathing was prohibited due to over-germination. Is that still true today? Grambow: You are addressing several problem areas here. Firstly, in Bavaria we have a special disinfection program for the Isar's bathing water quality. This is not yet standard everywhere in Central Europe. Globally, contamination is usually fought by chlorination, which is of course an absolute ecological disaster. Secondly, heavy rain can always lead to contamination, many organic substances are then carried along and the quality of the bathing water cannot be maintained if it is cloudy. TiB: Due to the increasing heavy rain, the sewer system is already overloaded in some places. How do you assess this problem? Grambow: We already have the impression that the distribution of precipitation is changing so much as a result of climate change that our sewer networks are sometimes quite challenged and sometimes overwhelmed. The torrential rain that overflows a sewer system is increasing, and not just here, but at least across the entire Alpine arc. Our immediate neighbors, our colleagues in Austria and Switzerland, make similar observations. 8 TiB: What options for action are there? Grambow: We have already reacted to the larger floods and are planning about 15% higher dams for flood protection on the rivers. This is a little more difficult with the sewer network, since most of the channels exist and cannot be easily adapted. What you do, above all, is that you recommend the municipalities that are responsible for keeping their sewer cadastre up-to-date in order to be able to calculate. Because then I can calculate how something changes and can then provide technical remedies such as Create storage ducts or storage basins. Sometimes you have to build another canal, but then you should switch to rainwater systems. The new buzzword in this context is urban flash floods and the problem here is not that the canal overflows, but that the water cannot flow into the canal in the first place. And sewers cannot be built so large that every eventuality can be taken into account, but there is also a range of measures that can be taken with the sewer network. A new development is e.g. the installation of local weirs in the canal to retain water in certain areas. Anyone who thinks that the technical solutions here are exhausted is wrong. But it starts with the fact that I know my own network really well. TiB: How do you rate knowledge about the water networks in Bavaria? Grambow: The data situation is very good in the larger cities and municipalities. It gets a little more difficult with the smaller communities. What we do know is how much has been invested in the churches. The new building is always transparent, it becomes diffuse during maintenance and renovation. TiB: Keyword renovation: There is an urgent need for renovation for many wastewater systems and sewage treatment plants from the 1960s and 1970s. Who has to pay for this and are there any subsidies? Grambow: Indeed, the ravages of time are gnawing at the infrastructure, which has been installed for over 30 billion euros over the decades, and we have all given the issue too little importance in the past. Now there is a certain investment backlog, but as with all technical installations, you shouldn't wait too long with maintenance. On the question of costs: water supply and disposal are self-supporting municipal facilities from the start, i.e. they have to finance themselves completely through fees and contributions. But now comes an important point: In rural areas, the costs for the water infrastructure are disproportionately high for technical reasons.And that's why the decision was made very early in Bavaria to keep the rural structures stable, also through financial support. And that is a politically far-reaching, wise decision to create equal living conditions in town and country. This principle has proven itself extremely well. In relation to the water infrastructure, this means that we are supporting the new building and thus making the initial investment easier.

9 FOCUS tert have. The systems themselves have to support themselves, but for repairs and maintenance there is now a hardship subsidy in Bavaria, which ensures that a generation should not be burdened with expenses beyond a certain level. This means that wherever the investment in the water infrastructure over the past 20 years has exceeded a certain level, the state continues to support around euros per inhabitant. For the next few years we have the mandate of the Bavarian State Parliament to help with such hardship cases with up to 70 million euros annually. Of course, these will mainly be the rural, structurally weaker areas. TiB: The fertilization with sewage sludge is to be banned in the next few years and instead the phosphorus contained in the sludge is to be recovered by incineration. Can small municipal sewage treatment plants still work economically at all? Grambow: Sewage sludge contains a lot of difficult substances, and we are actually very happy that these substances are collected in one place. And in recent years we have learned more and more that it is not a good idea to then distribute the many substances that are not good for us as evenly as possible across the country. It's a shame about the nutrients we need in sewage sludge. However, phosphorus recovery, for example, is still in its infancy. As far as costs are concerned, the retrofitting will start with the large plants and with regard to sewage sludge, structures will develop over time. TiB: A look into the future: What developments in the field of wastewater management can we expect? Grambow: What worries me a lot is that our sewage disposal, our sewage treatment plants can do a lot, but not everything. For example, the medicines that are also used in cattle breeding today, as well as many nutrients from agriculture, in particular nitrate, but also phosphate, we can no longer filter out. Another problem area is the large amount of plastic waste, about the microbeads contained in cosmetics in particular, we cannot yet say whether they are a problem or how big the problem is. However, the area of ​​textiles made of fiber pelts has not been clarified. Fibrous pelts lose a lot of fibers in the wash cycle; the final assessment is still pending. It is really important that we keep an eye on all these substances. TiB: Do you also pursue the topic of energy recovery from sewage treatment plants? Grambov: Absolutely! Over 10 years ago, Prof. Faulstich, then TUM, had the visionary idea of ​​turning the sewage treatment plant into a supplier of energy and raw materials. And these developments in energy recovery and raw material recovery go on and on. The energy transition is only one side of the coin. We have made huge progress on the other side of raw material recovery in recent years. We have also supported this with funding programs and it goes even further. I'm really excited to see what technology is still lying dormant. TiB: Thank you for the interesting insights and the nice conversation. Interview conducted by Fritz Münzel and Silvia Stettmayer INFORMATION IFAT: World's leading trade fair for water, sewage, waste and raw materials management May 30 to June 3, 2016, Early bird discount: until May 27, 2016 AVEC International Congress for Advanced Vehicle Control, September 2016 Over 130 scientific contributions from the world's leading institutions, including: Driving dynamics, steering, braking, tires, suspension Integrated chassis control systems Active safety and driver assistance systems Sponsor: 9

10 FOCUS Technology of municipal wastewater treatment Wastewater treatment is carried out with the aim of extensive nutrient elimination as well as hygienic aspects in order to guarantee a consistently high water quality. Flow diagram changed according to Gujer, 2007 Particularly in view of the fact that our drinking water is partly recovered from reservoirs fed by treated wastewater, wastewater treatment also serves to protect drinking water. The purification of municipal wastewater is a multi-stage and complex process that requires a lot of control and energy, so that sewage treatment plants are often the largest municipal energy consumers. The wastewater supplied is usually treated in three stages. In the first stage there is a purely physical separation of waste water constituents. This usually starts with a coarse sieve (the so-called rake), which holds back coarse material such as twigs, hygiene items, coarse leftover food and the like. The screenings are either composted and used in landscaping or thermally recycled. Downstream of the rake, there is often a sand trap and a fat trap (sometimes in a combination), with inert heavy materials such as gravel and sand being separated in the first and light materials such as fats and oils in the second. While the resulting sand is usually recycled in the construction industry, the resulting fat is a well-suited substrate for biogas production, which is why it is fed to the digester together with primary and excess sludge. Said primary sludge then occurs in the last stage of the mechanical wastewater treatment, where the flow rate of the wastewater is shown in Fig. 1: Flow diagram of a typical municipal sewage treatment plant. 10 sized primary clarifier is reduced so that particulate (undissolved) substances can settle. These are in particular the solid waste water constituents, such as faeces and food residues, which in turn also have a corresponding biogas potential. The remaining wastewater is now largely free of solids, but it still contains organic compounds and nutrients (nitrogen and phosphorus compounds) in dissolved form. The dissolved pollutants are eliminated in the second, biological stage. This stage consists of a system of aeration tanks and secondary clarification. With the help of aerators, oxygen is introduced into the aeration tank, which enables the microorganisms located in it to aerobically metabolize the substances in the wastewater (with oxygen). While carbon compounds are either mineralized to CO 2 or incorporated into new biomass, nitrogen compounds oxidize to nitrate (NO 3) as part of what is known as nitrification. A further step, called denitrification, is necessary to remove the nitrate. For this purpose, the said nitrate and a carbon source (usually in the form of the organic compounds dissolved in the wastewater) are offered to the microorganisms in a separate, non-aerated part of the basin, whereby the nitrate is breathed in as an alternative electron acceptor to oxygen, so to speak. The first part of the activated sludge tank (upstream denitrification) often serves as the denitrification zone, whereby the nitrate-containing wastewater has to be returned from the aerated part. The microorganisms (biomass) also have to be returned, since the efficiency of the activation tank depends heavily on the mass of active organisms. Therefore, with the downstream clarification, which works in the same way as the primary clarification, clear water is separated from the biomass. The biomass is then either returned to the activation process or initially further concentrated as so-called excess sludge together with the fat from the fat trap and the primary sludge in a thickener. If necessary, the clear water is finally disinfected (e.g. when discharging into a bathing water) and then discharged into the respective receiving waters (usually streams or rivers). The third stage of wastewater treatment is then chemical processes for further wastewater treatment. This then particularly includes chemical phosphorus elimination, since phosphorus can only be eliminated to a limited extent by biological means. For this purpose, iron or aluminum salts are added to the wastewater at the end of the activated sludge tank, whereby the phosphorus is precipitated in the form of poorly soluble compounds and removed from the system with the sewage sludge. The fresh sludge from the thickener is finally fed to the digester for anaerobic (with exclusion of oxygen) sludge stabilization. Microorganisms convert the organic substances, among other things, into high-energy methane, which is used to generate electricity and heat. This allows some of the energy in the wastewater to be recovered. Using newer energy-efficient processes, which are also being researched at the Department of Urban Water Management at the Technical University, sewage treatment plants should use significantly less energy in the future or run completely self-sufficient in terms of energy. The sewage sludge that arises from the digester is dewatered, with the sludge water going back into the main flow of the sewage treatment plant together with the liquid phase from the thickener. In the past, the remaining solid was often used agriculturally as a soil improver. However, due to the harmful substances (heavy metals, pharmaceutical residues, etc.) that may be present in sewage sludge, the current trend is towards thermal recycling. Dr. Konrad Koch, Prof. Dr. Brigitte Helmreich, Prof. Dr. Jörg E. Drewes Chair for Urban Water Management, TUM

11 FOCUS Wastewater networks must be maintained Wastewater networks have been built for generations with the aim of safely discharging the collected wastewater from the settlement areas in order to achieve hygienic conditions there. This made a significant contribution to the health of the population, and epidemics such as plague and cholera could be contained. A modern sewage system also fulfills other important functions, such as ensuring a high level of drainage comfort, i. H. the rainwater is removed in such a way that flooding is normally avoided. Therefore, a functioning, tight, efficient sewer system is an important part of urban infrastructure. In Germany, more than km of public sewers and private sewers twice as long were built for this purpose. 96% of the population are thus connected to a public sewage system with subsequent biological sewage treatment and thus enjoy safe and good living conditions. In order to achieve this high standard, considerable financial efforts have been required over the past hundred years, several billion euros per year in the last few years alone. This makes the sewage system, with around 700 billion euros in Germany, the largest asset of the municipalities and cities. The sewer network in Germany shows an age distribution of 28% over 50 years, 15% over 75 years and 6% over 100 years. This shows that for reasons of age, reinvestments are necessary to maintain this important system (DWA 2009). The sewer pipes are subject to heavy loads that can lead to damage due to a variety of effects on the underground sewer system, from defects in the structural condition to defects in the installed condition (see Fig. 1) to operation. Various studies on the condition of the sewer system show that there is a relatively high need for rehabilitation with around 15% of the total sewer system (DWA 2009, TUM 2015). This condition is reflected in the following aspects: high levels of extraneous water in the sewer frequent flooding clogging the occurrence of soil material in the sewer. In order to avoid damaging effects on the soil and groundwater, overloading of the sewage systems, and destruction of the structures, a regular review and inspection of all sewage systems is necessary, with subsequent renovation of structures that no longer meet the requirements. The maintenance of the sewer system requires the following steps (LfU 2010): Inventory (sewer cadastre) Condition assessment (visual and leak test) Condition assessment (condition classes) Renovation concept (renovation type) Object planning (repair, renovation, renewal) Construction (preparation, implementation, monitoring) Maintenance must refer to both the public and the private sewage network, as only a holistic approach can achieve the goal of a dense, efficient network. The necessary financial expenses for the maintenance and operation of these networks, both publicly and privately, must be increased significantly in the next few years, as otherwise a depletion of values ​​with significant negative effects on people and the environment is to be expected on the one hand and a shift in costs to on the other future generations takes place (impulses per channel 2014). With an already low average burden on the population of around 140 euros per year per inhabitant, this is quite reasonable and affordable (Thimet, Günthert 2014). Prof. Dr.-Ing. F. Wolfgang Günthert University of the Federal Armed Forces LITERATURE DIRECTORY Graphic: University of the Federal Armed Forces Fig. 1: Effects on a sewer pipe. DWA 2009: German Association for Water Management, Sewage and Waste e. V. (DWA) (Ed.): State of sewer systems in Germany TUM 2015: State of public sewer systems in Bavaria (Final report of TUM, Chair for Urban Water Management LfU 2010: Guidelines for the inspection and rehabilitation of municipal sewers, Bavarian State Office for the Environment (2010) Impulse per Canal 2014: Catalog of requirements for functional public and private wastewater systems, Juliane Thimet / F. Wolfgang Günthert: Abwasserbesichtung Technik und Recht, practical series of the Bavarian Municipal Association (2014) 11

12 FOCAL POINT Economic climate protection in sewage treatment plants Up to now, a less energy-efficient sewage sludge treatment has been used in small sewage treatment plants. Thanks to new developments, these sewage treatment plants can also be converted economically to energy-efficient processes. This was proven by BBI Bauer Beratende Ingenieure GmbH in a pilot project at the Bad Abbach sewage treatment plant. Bad Abbach sewage treatment plant, in the background the primary treatment, the machine house and the digester. Small sewage treatment plants = high power consumption? The Bad Abbach sewage treatment plant was operated with a population equivalent for wastewater treatment using the activated sludge process. Due to the community development, the capacity of the sewage treatment plant had to be expanded to the population equivalent. In sewage treatment plants of this size, sludge stabilization was achieved in the past together with wastewater treatment by supplying oxygen in aeration basins. This aerobic sludge stabilization results in comparatively low investment costs, but high operating costs due to the electricity consumption for aeration. In the case of larger sewage treatment plants with a population equivalent or more, the sludge is stabilized in the digestion tower with the exclusion of oxygen. This anaerobic sludge stabilization is due to higher investment costs, e.g. for the digester with lower operating costs 12 at the same time. With anaerobic sludge stabilization, the aeration times can be shortened and the gas produced during sludge digestion can be used to generate electricity and heat. In addition to these savings in energy costs, disposal costs are also reduced due to the lower amount of sewage sludge. According to the current opinion of the experts, the maintenance of the aerobic sludge stabilization despite higher operating costs due to lower investment costs was the more economical solution for an expansion to population equivalents planned for the Bad Abbach market. That is why sewage treatment plants with anaerobic sludge treatment in the digestion tower are the exception up to an expansion of the population equivalent. In wastewater treatment plants of this size, the investments for a digestion tower in a classic design were in almost every case uneconomical, despite the savings in operating costs. Sewage treatment plant of the future The expansion of the Bad Abbach sewage treatment plant was considered by BBI Bauer Beratende Ingenieure GmbH in the planning process under the conditions of increased electricity prices and the development of cost-effective system tanks for biogas plants. The idea was to transfer these developments to municipal sewage treatment plants through project-specific adaptations. The shape of the container, the type of heating and the gas container of existing system solutions from biogas technology have been retained. However, the circulation, the thermal insulation of the container and operational traffic routes had to be adapted to the conditions of a municipal sewage treatment plant. With these adjustments, the economic viability of the anaerobic sludge treatment could be proven mathematically in the case of the need for action at the Bad Abbach sewage treatment plant, even with an expansion of the population equivalents. The project was therefore registered in 2011 by the Bavarian State Ministry for Environment and Health for the pilot project competition energetic optimization of municipal sewage treatment plants by retrofitting an anaerobic sewage sludge treatment. The jury's choice for this trend-setting concept within the framework of the sewage treatment plant of the future project fell on the Bad Abbach sewage treatment plant from the eleven applications received.During the expansion of the Bad Abbach sewage treatment plant from to population equivalents, the essential sub-measures of new construction of primary clarification basin, new construction of digester in a cost-effective system construction and new construction of machine buildings for sludge pumping station, gas treatment, gas conversion and sludge dewatering were implemented. The energy-rich primary sludge is already separated in the primary clarifier. The sludge is stabilized in the digester and gas is generated in the process.

13 FOCAL POINT This means that electricity and heat are generated in a combined heat and power plant as required. In addition, the existing ventilation in the aeration tanks was replaced by new, energy-efficient elements. The primary clarification. Economical sewage treatment plant The expansion of the sewage treatment plant was implemented in two stages. As a preliminary measure, the ventilation in the aeration tanks was renewed. This was intended to create a reference state with energy-efficient ventilation for joint aerobic sludge stabilization so as not to falsify the results of the pilot project. The new aeration in the aeration basins was therefore put into operation around a year before the sewage sludge treatment was converted. This reduced electricity consumption from around kwh per day to 790 kwh per day. With the commissioning of the primary clarifier and the digester, the sludge stabilization was switched from joint aerobic to separate anaerobic stabilization. After a start-up phase of around three months, operation was largely stable. The digester, adapted from biogas technology for the needs of municipal sewage treatment plants, has proven to be functional and operationally stable. It was thus possible to show that these tanks, which are much cheaper than classic digesters, can also be used in sewage treatment plants if they are adapted to the characteristics of the sewage sludge. In spite of the additional operation of a sludge dewatering system, electricity consumption has been reduced from 790 kwh per day to 750 kwh. With anaerobic sludge treatment, an average of around 310 m³ of digester gas with an average methane concentration of 61% is produced every day. By converting the digester gas into electricity in a combined heat and power plant with an electrical output of 30 kW, 500 kWh of electricity are generated daily. The level of self-sufficiency for electricity from the anaerobic sludge treatment alone is 67% and the electricity consumption has been reduced to an average of 250 kWh per day. The anaerobic sludge treatment in the digester usually takes place at process temperatures of 35 C to 40 C. The thermal energy required for heating up the sludge and compensating for the losses via the container surface is generated when the digester gas is converted into electricity. The optimal insulation of the system tank, determined in an extensive simulation, is a compromise between the prevention of additional heating with gas, which is necessary in the cold season, and the dissipation of waste heat from the combined heat and power plant, which is necessary in summer. Due to the high volume of gas, the new and existing buildings have been heated to a large extent without additional consumption of fossil fuels. This leads to further savings in primary energy consumption for the operation of the sewage treatment plant. The amount of sludge to be disposed of is also reduced by around 30% by switching to anaerobic sludge treatment. This means that the savings forecast in advance have even been exceeded. The cost-effectiveness of the conversion of the process has not only been proven mathematically but also in practice at the Bad Abbach sewage treatment plant. In addition to economic efficiency, the implemented project makes a significant contribution to climate protection. The reduced electricity consumption is associated with a reduction in CO 2 emissions. In addition to the cost-effectiveness of the process changeover, the extended sewage treatment plant will of course continue to fulfill the original task of wastewater treatment to a high degree. Lighthouse project With the title lighthouse project, the Environment Cluster Bavaria recognizes projects that make an exemplary contribution to the development of environmental technology in Bavaria. From the applications received, the project energetic optimization of the wastewater treatment plant Bad Abbach by retrofitting an anaerobic sewage sludge treatment was selected and awarded as a flagship project in 2014. Dipl.-Ing. Kai Christensen Project Manager BBI Bauer Consulting Engineers Dr.-Ing. Werner Weigl Member of the Board of Management of the Bavarian Chamber of Engineers and Managing Partner of BBI Bauer Beratende Ingenieure GmbH 13 All photos: BBI Bauer Beratende Ingenieure GmbH

14 FOCUS The largest solar sewage sludge drying plant in southern Germany One of the largest solar sewage sludge drying plants in the world was successfully started at the beginning of the year at the Bayreuth sewage treatment plant: On an area of ​​m², the sludge is dewatered by population equivalents and dried fully automatically, with waste heat utilization and exhaust air treatment. From dewatering to the dryer The digested sludge with a dry matter content (= dry residue, the ratio between the dried mass and the initial mass, editor's note) between 2.5 and 3.5 percent is dewatered by two centrifuges and automated with screw conveyors transported into the solar dryer. In a Venlo glass greenhouse, the press cake is evenly distributed over five different lines. If one or more lines should fail, the control automatically adjusts the task so that the remaining lines process the sludge that arises. The dewatered sludge can also be conveyed directly into a container in an emergency. From press cake to dry granulate The HUBER Sludge Turner SOLSTICE conveys the press cake from the feed through the greenhouse, the sludge releases moisture into the air until it has become dry, round, granular granulate at the end of the drying bed. The specialty of the mud turner is its unique tool: the mud is moved with a constantly rotating double shovel. This rolls the sludge into a round, compact grain and at the same time brings it into close contact with air. The double shovel can also be used to move the sludge in a targeted manner. The sludge turner picks up sludge in one of the two shovels and places the turning tool horizontally. Not only can the dry sludge be mixed back into the wet sludge, but the sludge can also be fed and discharged on the same side of the dryer as it is implemented in Bayreuth. The turning tool of the mud turner is arranged in such a way that 99 percent of the mud-covered area is processed. The double shovel is so close to the boundary walls that almost no mud remains in the corners. The turning blades are driven by powerful motors. Detailed representation of the entire system. 14th

15 FOCAL POINT floated so that up to m³ per hour of sludge can be shifted. In the entrance area, the mud is still quite damp, which means that composting effects can start if the sludge bed is not treated. To counteract this effect, the machine can turn over the organically highly active sludge every 15 minutes and suppress the undesired compost effects. This intensive, complete sludge bed treatment promotes dehydration and improves the mechanical workability of the sludge. In addition, the odor emission is reduced and a dry, stable end product is ensured, a free-flowing, easy-to-use dry granulate. When the air saturated by the moist sludge reaches the feed side of the dryer, it is discharged from the system via an exhaust air treatment. The two-stage washer was manufactured under factory conditions in order to then only set it up on the construction site. In this way, all seals could be carried out in high quality. The air flow through the scrubber takes place in cross-flow, so that the pressure losses due to the exhaust air treatment are reduced and this goes hand in hand with low power consumption. The dry granulate is conveyed to a bucket elevator via screws located in the ground, which conveys the sludge into a flat silo. The sludge is quickly discharged from the flat silo and the granulate can either be unloaded open, i.e. into a tipper truck, or closed into a silo vehicle with the loading bellows. The flat silo is set on weighing cells. In this way, on the one hand, the filling level can be checked, and on the other hand, it can be ensured that the transport vehicle is not overloaded. Dipl.-Ing. (FH) André Großer Huber SE, Berching Wind and heat dry the sludge A number of heating registers are installed above the sludge bed, which bring waste heat from a neighboring biogas plant into the drying process. The glass house is equipped with a special condensate drainage system, so that the sludge does not re-humidify. The heating registers are galvanized to prevent corrosion. The dry and warm air is blown over the dryer surface with fans and guided through the hall. For this purpose, fans are used that are speed-controlled, depending on the desired setting, the fans can rotate very quickly and achieve a strong turbulence in the air on the sludge bed surface or can also be operated slowly in an energy-optimized manner. The sewage sludge press cake is evenly distributed on five different lines. In the picture below: The system has been in operation since the beginning of 2016. TECHNICAL DATA m³ / a digested sludge after dewatering (28% DR) m³ / a digested sludge after solar drying (75% DR) m³ / a water evaporation (incl. Waste heat from biogas plant) m³ / a water evaporation (without waste heat from biogas plant) Without waste heat from the biogas plant a dry matter content of 63% can be guaranteed in pure solar operation. Area use: m² for the Venlo glass greenhouse with integrated exhaust air treatment 300 m² over 2 floors for the machine building with drainage, chemical room, heat transfer station, dry granulate storage and the switching and Control room All photos: Huber SE 15

16 FOCAL POINT In the course of the rehabilitation of the Erlangen sewage treatment plant, new types of processes were installed in the secondary clarification and activation basins. Efficient oxygen supply in the aeration tank INVENT Umwelt- und Verfahrenstechnik AG from Erlanger has recently developed a new type of exhaust air measurement system. This allows a new type of access to efficient oxygen input control in aeration tanks. The ALPHAMETER is used to permanently determine the current oxygen consumption rate of the activated sludge in up to 2 basin zones, in each of which an exhaust air collection hood floats. It analyzes the waste air from nitrification biology with regard to oxygen, carbon dioxide and water vapor content. From this, it determines the current oxygen consumption rate and can accordingly provide the currently required amount of compressed air for the relevant basin area as a control variable. This controlled variable, which is directly related to the reduction of the pollution load, allows a fast-forward control of the gassing with extreme efficiency, in contrast to the classic control based on a predetermined value for the dissolved oxygen. In addition, it determines the oxygen transfer efficiency and allows a statement to be made about the alpha value of the activated sludge (= the alpha value describes the difference between the oxygen input in pure water and that in activated sludge. Here: Alpha * F, i.e. the link with the so-called digestion factor as an identifier for the state of wear of the ventilation system). For the exact determination of these process parameters and the new control signals, the device also uses the signals of dissolved oxygen and the temperature in the relevant activated sludge basin area, which are usually already available. It offers a new way of looking at the nitrification process that goes well beyond the usual level on the basis of process-typical parameters that were previously not available in real time. Along with this, it allows the energy-related optimization of the nitrification process up to the comparatively very efficient, energy-saving controllability of the oxygen input. The new exhaust air measurement system has been proving its worth in practical test operation at the Erlangen sewage treatment plant since May 2014, along with several other references outside of Germany, four parallel nitrification lines with 3 cascades each and with a denitrification line connected upstream, of which road 1 was initially run with the ALPHAMETER in the field test has been. In close cooperation with the plant management, the use of all potentials with safe operation of the plant (compliance with discharge values) will continue to be tested successively. For comparison with the classic operating mode, normal operating parameters, such as the cascade-related default values ​​of the dissolved oxygen, of the directly neighboring streets 1 and 2 with otherwise real comparability (load, inflow) were always the same for a first stage of the integration of the exhaust air measurement system Wise kept and / or modified. Several successful integration steps have already shown significant energy savings. The test phase was mutually extended and expanded. The use of the ALPHAMETER serves as a demonstration for potential customers of the Erlangen company, not only in the German-speaking area. The major differences between this innovative process management compared to the classic regulation of the compressed air supply are: On the one hand, with the exhaust air recording and the oxygen consumption rate of nitrification biology determined from it, one is orders of magnitude closer to the real events All images: INVENT AG exhaust air collection hood for analyzing the oxygen , Carbon dioxide and water vapor content. 16

17 FOCAL POINT of the aerobic pollutant load reduction, as it allows the assessment of the excess dissolved oxygen resulting after the oxygen consumption, which has so far been recorded as a classic control parameter for the oxygen supply. Secondly, the precise determination of the currently required amount of compressed air for the pool area in question offers a quantitative control option for the amount of air to be supplied in contrast to the previously qualitative control variable (more or less compressed air required if the value does not match the setpoint). Scheme of the integration of the alphameter in the system. Consequences of the new control strategy: The sensor-related fluctuations in the amount of compressed air supplied (dissolved oxygen signal) are drastically reduced. The dissolved oxygen value, which is now set according to the specifications, is a constant (apart from sensory measurement value fluctuations) that only influences the amount of air determined from the consumption when the target value changes. This can be registered as a signal smoothing of the value of the recorded dissolved oxygen, which up to now has tended to vary more strongly. The precise supply of the air quantity currently required for the degradation process via the relevant control unit lowers the actual air requirement to precisely this level, in contrast to the oversupply due to the significantly more fluctuating values ​​of the value of dissolved oxygen in the recorded surface area on the one hand, which on the other hand also only emerges subsequently of the relevant activated sludge tank. The fluctuations in the air requirement due to these current consumption values ​​are lower because they are linked to the current pollutant degradation process in the sense of a fast-forward control instead of a follower control using dissolved oxygen. The reduction in the amount of air that has been fed in unnecessarily too much in the previous way is more intense, the stronger the pollutant load is per se (i.e. the more pronounced under high-load conditions during the day than under pronounced low-load conditions). Results from the previous field tests All the compressed air savings result in direct savings in the energy required for the generation of compressed air. In the case of the results already available at the Erlangen sewage treatment plant, the savings are usually at least 25% compared to the conventional compressed air supply. In the case of higher load conditions (pollution loads) in nitrification biology, savings of up to 50% in some cases were even found. Ute Klausner INVENT Umwelt- und Verfahrenstechnik AG Erlangen Optimized secondary clarification basins Final clarification basins (NKB) usually represent the last procedural stage of wastewater treatment. The limit values ​​of the system should be adhered to in these basins if no further cleaning requirements are made. The official values ​​(notification values) with regard to the filterable substances (AFS) for the Erlangen sewage treatment plant are 8 mg AFS / l. This very low and therefore strict limit value is currently guaranteed according to the state of the art with conventional secondary clarification and downstream sand filtration. A procedural improvement could only have been achieved with the creation of additional basin volume in the area of ​​the secondary clarification, explicitly through the cost-intensive construction of a further secondary clarification basin. In order to counteract these disadvantages, the existing secondary clarifier was examined in terms of flow technology by the Dresden hydrograv GmbH and the possibilities of optimizing the existing structure were simulated. After the fluidic investigations and proposals by hydrograv GmbH, sewage treatment plants such as Großostheim, Altomünster and Odelzhausen successfully rebuilt with a height-adjustable intake structure. On the basis of these successes, the Erlangen wastewater treatment plant was also equipped in order to achieve a guaranteed minimum AFS in the future at the secondary clarifier drain. In the course of this optimization, height-adjustable inlet structures, so-called hydrograv adapt, were installed in two basins.For the third secondary clarifier, which is already somewhat larger in volume, the flow simulation resulted in a cost-effective optimization of the inlet geometry by retrofitting a sheet steel jacket on the existing central structure and circumferential flow baffles. hydrograv adapt is a height-adjustable inlet structure for secondary clarifiers, which adapts to the fluctuating loads (dry / rainy weather, summer / winter) in the inlet in terms of height and opening width and thus always creates an optimal situation in the tank for wastewater treatment and thus a significant increase in the performance of the secondary clarifier allowed. This is achieved by the fact that even when the sludge level is very low, the freshly flowing sludge is fed directly into the sludge bed and thus no longer comes into contact with the clear water. This creates a flock filter in the inlet area of ​​the secondary clarifier, which retains even the finest particles and thus enables significantly lower AFS in the drain. In addition, the hydraulic load-bearing capacity of the secondary clarifier is verifiably 17

18 FOCAL POINT In order to secure a minimum AFS in the future at the secondary clarifier drain, height-adjustable inlet structures were installed in two tanks. The different settings of the inlet from left to right: In dry weather, in rainy weather and in heavy rain. increased and also the sludge displacement is reduced, since settled sludge in the rising sludge bed is not whirled up by the inlet, which is then set higher. Due to the lower sludge levels due to the intake structure, significantly higher material loads can be treated. This in turn represents a clear advantage over static systems. The success was investigated by the drainage company of the city of Erlangen in cooperation with the Miller engineering office in a measurement campaign. Over a period of five months, 2-hour mixed samples were taken with dry, rain and night influx. The secondary clarifier with hydrograv adapt now almost reaches the drainage values ​​of a sand filter. The mean value of the filterable substances of the two adapt basins was only approx. 3 mg / l, the highest value ever measured was 5.2 mg / l. This exceeded the company's expectations of the height-adjustable intake structures. With the optimization of the secondary clarifier, the cleaning performance of the Erlangen sewage treatment plant is guaranteed for all load cases. Furthermore, more stable plant operation, higher plant availability in the event of an inspection and energy savings during filtration are achieved. In the Erlangen example, hydrograv GmbH was able to demonstrate the benefits of CFD flow simulation as an engineering tool and successfully ensure that the wastewater treatment of the Erlangen sewage treatment plant could be further optimized with the flow-optimized and height-variable inlet structure. Dipl.Ing. Dieter Hilligardt hydrograv GmbH, Dresden All pictures: hydrograv After the renovation, the basin was flooded. 18th

19 BACKGROUND Max von Pettenkofer A sewer system for On July 15, 1854, the First General German Industrial Exhibition was ceremoniously opened in the Munich Glass Palace by King Max II. Exhibitors from all over the world presented technical marvels. During the opening speech by the king there was a death one of the inspectors at the entrance collapsed. At first it was believed that it was a stroke. In the next few days, however, many exhibition employees suffered from severe diarrhea. On July 27, 1854, the 39-year-old day laborer Peter Stopfer was diagnosed with cholera, which he succumbed to two days later. The number of sick people grew rapidly and the epidemic broke out in. Many foreign guests and high-ranking residents of Munich fled the city. It was not until September 30, 1854, when the committee convened to resolve measures against the epidemic breakup announced the end of the cholera epidemic with fatalities. The beginning of the slaughterhouse to investigate the causes One member of the investigative commission was the 36-year-old Max von Pettenkofer (). The son of a farmer had studied pharmacy, chemistry and medicine and was appointed professor of medicinal chemistry by the Ludwig Maximilians University in 1847. The question of why cholera was so raging and how one could prevent such an epidemic in the future should concern him from now on. Pettenkofer did not look for the causative agent of the disease, but made the air contaminated by decomposition processes partly responsible and recommended regular ventilation or siphons for the drains in kitchens and toilets, which Pettenkofer opened in his institute for hygiene, the first in the world. He soon realized that the quality of the wells was also severely impaired by the urban sewage. On his recommendations, the government of Upper Bavaria commissioned the city administration with the expansion of a sewer system. The civil engineer and later town planner Arnold Zenetti planned and supervised the construction of the first sewer system (construction period 1862 to 1887). In the beginning, the residents' complaints about the higher taxes and the sewer, the stench of which was particularly noticeable in summer, increased. The sewers often had to be cleaned. The farmers were also against the sewer system. So far they had taken the feces out of the city and used them as fertilizer on their fields. Now they forfeited their payment of 30 guilders per emptied toilet pit. Pettenkofer debated regularly in committee meetings, wrote newspaper articles and gave public speeches. In addition, the cement composition had to be improved so that the sewage does not decompose the sewer pipes. It was not until 1899 that the alluvial sewer system was finally introduced, which led to the establishment of the flush toilet and solved the odor problems. By 1900, 78 percent of the Munich population were already connected to the sewer network. The return of cholera When cholera broke out again in 1873, as in 1854, the Oktoberfest had to be canceled. Now at last Pettenkofer was able to assert himself with his expanded measures for hygienic urban renovation. He banned the slaughterhouses from the city center and in 1878 the central slaughterhouse and cattle yard was opened (see drawing). The third element in Pettenkofer's plan for improved urban hygiene was the drinking water supply. Since 1867, part of its water has been drawn from Thalkirchen, and from 1883 the Mangfall Valley, around 40 km away, was used for the water supply. Since then, to this day, its citizens have been able to supply its citizens with drinking water of excellent quality at any time, the last time cholera came to Europe as an epidemic and was particularly rampant in Hamburg. Not only was it spared, it was now known as the “cleanest city in Europe”, mainly due to its sewer system. Dr. Florian Breitsameter Deutsches Museum 19 Drawing: Grossmarkthalle