In our latest research project, DeWaResT [1], we are focusing entirely on Nature Based Solutions (NBS) to make used water from households reusable. It has long been a nuisance that high-quality drinking water is first used for flushing toilets and then has to be pumped to the sewage treatment plant, sometimes via long pipes. Afterwards, it is no longer available to the local water balance and leads, more or less well purified, to an unavoidable and, with decreasing runoff, increasing chemical pollution of the water bodies. It is already clear that rising temperatures are causing a sharp increase in water consumption in the landscape. At the same time, there is less precipitation in some regions of Brandenburg. As a result, groundwater levels are sinking and lakes and watercourses are drying out.

According to the European Directive 91/271/EEC and the Brandenburg Municipal Wastewater Ordinance (§7 BbgKAbwV), water abstraction from natural sources should therefore be reduced and treated wastewater reused wherever possible. However, high demands are placed on the reuse of treated wastewater in agriculture to protect the environment and products. It is estimated that the wastewater collected in decentralised collection pits in Brandenburg could cover up to 20% of the irrigation needs in agriculture if it were appropriately treated in a decentralised manner. In the future, the European Water Reuse Regulation (EU-WVVO) will regulate the requirements for purification and monitoring.

The contribution of our research project is to enable such decentralised water cycles. For this purpose, constructed wetlands are optimised in terms of process technology and combined with further purification stages as required. Such vegetated soil filters are particularly suitable for decentralised application due to their simple and robust operation. Integrated stages are designed to further remove germs and trace substances.

The innovative soil filter is compact and requires a very small surface area. Two pilot plants in Brandenburg are used for optimisation and further development. The Pehlitzwerder plant serves to prove its applicability at a remote natural camping site with very high nature conservation requirements in the middle of the Schorfheide-Chorin biosphere reserve. The second plant treats regular household wastewater. After completion of the investigations in 2023 and evaluation of the results, this new type of constructed wetland should be available for future decentralised applications. This is intended to close the gap in agricultural (economic) water reuse. This research is funded by the Federal Ministry of Education and Research (BMBF) in the funding measure “KMU-innovativ”, technology field “Resource Efficiency and Climate Protection”, application area “Sustainable Water Management”. The project partner is KWB Kompetenzzentrum Wasser gGmbH, Berlin.

Further information: Heribert Rustige

[1] Decentralised wastewater treatment and water reuse for regions with seasonal drought stress

At the Berlin children’s and youth circus CABUWAZI, climate change and its consequences are omnipresent. This is particularly noticeable at the six locations in the city. The large circus tents heat up strongly in summer, as do the circus wagons and containers at the respective locations. For this reason, AKUT was commissioned to conduct a feasibility study for measures to adapt to the consequences of climate change as early as 2021. The study was funded by the BMU as part of the funding program for “Climate adaptation in social institutions” (duration 2020 – 2023). The results of the work, in which the children and young people as well as the circus trainers working on site were involved, were summarized in an exhibition that is now traveling from site to site.

“Climate change” has become a constantly recurring term. Not least through the student demonstrations of Fridays for Future, which have succeeded in putting the findings of science and the associated need for action on the political agenda. The children and young people experience first-hand what the consequences of climate change feel like during summer heat waves in the city.

However, what exactly climate change is and how it works is not clear to all children and young people as well as adults. For this reason, the desire arose to provide information about the topic within the framework of a traveling exhibition. Divided into three thematic areas, nine posters explain climate change and its consequences on both a global and a local scale. The three posters of the first block explain the origin of climate change and how it affects the people in the world and in Berlin. This will be followed by an analysis of the most exciting results of the CABUWAZI climate survey. This was conducted in February 2022 among regular visitors to the circus offerings and filled out by over 100 participants. Wishes and ideas that emerged were included in the catalog of measures to reduce the climate impact at CABUWAZI. These are presented and explained in outline form in the last part of the poster exhibition.

Download: Poster exhibition (german)

The staff of AKUT environmental engineers spent four years in Berlin on the research barge “Hans Wilhelm” studying the treatment of water from the River Spree. Now Heribert Rustige presented the results at the press conference of the Flussbad Berlin e.V. association. The association had commissioned AKUT in 2017 to test biological filters for improving bathing water quality in the Spree Canal. For this purpose, the research barge was placed at the location of the planned water filter at the height of the former Staatsrat building in Berlin’s city centre. Here it was closely observed by numerous tourists and Berliners and the AKUT team had to answer many questions about bathing in the Spree. This report summarises the most important answers.

With the help of the water analyses, it was found that the water quality in the Spree Canal had already improved continuously during the investigation period. This is especially true for the decreasing suspended particle contents, which caused an increase in the visibility depth in the Spree Canal. This trend was confirmed in comparison with long-term data series of the Spree and suggests already successful water protection measures in the city. Against this background and due to the tested filter variants, the cleaning concept can probably be realised with a filter size reduced by 2/3.

Based on the measured, briefly increased microbial loads on a few days a year, it was possible to clearly distinguish the polluted phases due to combined sewer discharges from the unpolluted phases. This enables a targeted step-by-step treatment in a resource-saving concept. This envisages a biofilter, which is normally sufficient to guarantee good bathing water quality according to the EU Bathing Water Directive. As soon as the automatic level measurements in the sewer network of Berliner Wasserbetriebe signal the overflow of combined water, additionally switched-on UV lamps would ensure safe hygienisation. Alternatively, filter operation could then be automatically interrupted for one to two days. This would also safely protect the following watercourse section from microbial overloading.

The research results allow the planning and dimensioning of biofilters for river water treatment. Five different filter materials with or without vegetation were examined. The elimination rates of E. coli and other indicator organisms were determined on the basis of loading tests. The best combination was found to be the use of porous expanded clay with reed planting. The results are an important addition to the know-how available so far, also for outdoor pools with biological water treatment. Experiences and technical innovations made here can be transferred to other water bodies and locations or enable targeted further investigations. We would like to thank the sponsors Xylem (UV -reactor), Rehau (drainage system) and ARGEX Belgium (expanded clay material) for their technical support.

Contact: Heribert Rustige

In bright weather, on the first day of loosening the Covid-19 lockdown in Brandenburg, Mayor Karl Tedsen and District Director Dieter Fuchs together with Katrin Covic, head of the citizens association Aktives Neustadt, opened the newly designed outdoor swimming pool in Neustadt an der Dosse on June 3, 2021. For nine years, citizens had to wait for the renovation of the old dilapidated swimming pool. Today, a biological filter replaces the water treatment that used to be operated with chlorine chemistry.

During the fundamental renovation, a diving facility with a 1-meter board and 3-meter tower was added to the pool. This resulted in an elaborate extension and redesign of the old concrete pool. The lining of the approximately 540 square meter pool with a high-quality PVC-free foil as well as the access via a natural wooden walkway now convey a warm and natural impression. The shallow access via the non-swimmer area is based on natural shallow banks, is barrier-free and invites the little ones to splash around.

The biological water treatment system consists of a simple soil filter located away from the bathing area. The substrate provides a large surface area for microorganisms to grow. Their task here is to break down organic pollutants, which can be carried in by bathers but also by the adjacent vegetation or birds. The advantages of this natural process lie in its adaptive properties and the avoidance of chlorine-organic compounds that would otherwise be produced during chlorination.  This means that the biofilm grows with its tasks: if the food supply in the biofilter increases, the biomass grows and increases the purification capacity. However, natural systems are comparatively sluggish, so a training period is required.

The focus of natural bathing water treatment is on the reduction of germs and phosphate. While undesirable bacteria are preyed by the protozoa on the biofilm, phosphorus can only be adsorptively bound to the filter material. For this purpose, the biofilter was supplemented by a regenerable phosphate filter, because the more phosphate is bound there, the clearer the water in the bathing pond remains.

With this solution, the city of Neustadt (Dosse) opted for a cautious renovation of the public swimming pool, taking into account the existing building fabric. The regional planning offices s quadrat m, freelance architects Sylvia Markau and Steffen Michaelis from Kyritz and VORLAND, landscape and open space planning Susanne Geitz from Wulkow were entrusted with this task in conjunction with the specialist planning office for ecological water treatment AKUT Umweltschutz Ingenieure Burkard und Partner, Heribert Rustige.

Contact: Heribert Rustige

The Abwasserverband Saale-Lauer, operator of the wastewater treatment plant built in the late 1970s (city of Bad Neustadt an der Saale, Lower Franconia), is optimizing the wastewater treatment plant and adapting it to the stricter environmental requirements. Priority has been also given to the stability of the cleaning performance and energy efficiency.

AKUT was commissioned in 2018 to identify expansion and optimization options for the wastewater treatment plant. Several modules were developed, of which the fluidic optimization of the denitrification basin was practically and successfully completed at the end of 2020.

Among other measures, the inlet and the circulation of the denitrification stage had to be hydraulically optimized. In the medium term, an expansion of the treatment plant is also planned, which is increasingly reaching its loading limits. Reconstructions from previous years were subjected to a weak-point analysis, which aimed at stabilizing the effluent quality and achieving a more energy-efficient operation.

The denitrification stage was found to operate below optimum cleaning performance.  The cause was identified as inadequate hydraulics in the inlet area. Furthermore, sludge accumulation occurred in the basin due to unfavourable flow guidance and non-optimal agitators.

In 2020, the closure of the old distribution channel and the adaptation of the threshold structures were implemented in accordance with the hydraulic calculation carried out by AKUT, so that the entire water flow and the entire return sludge is now routed through the denitrification stage.

In order to improve the circulation behaviour of the wastewater and to avoid the previously observed sludge deposits on the basin bottom in the future, concrete elements calculated and manufactured for the application were embedded in the longitudinally divided structure and the existing corners in the basin were optimally designed.

The newly installed, slow-running propeller agitator, the thrust of which is adapted to the different recirculation and sludge return feeds as required, results in energy savings of 50% compared with the previous agitators.

Since the spread of Covid-19 worldwide it has become one of the few certainties that meeting hygienic standards is one of the most effective forms of prevention. Thus, for users of water and sanitation services, the continuity of water supply becomes more than ever a major public health issue. But the pandemic puts Water Supply and Sanitation Providers (WSSPs) at risk and challenges.

AKUT has a vast experience in international cooperation in Latin America, where it has worked on projects in cooperation with GIZ (Deutsche Gesellschaft für Internationale Zusammenarbeit)  consulting for WSSPs. Recently, AKUT has opened a new office in Kampala, Uganda, where it is expanding its activity also in Africa. Therefore, AKUT decided to support the WSSPs in this challenge of the Covid-19 pandemic.

Our initiative of knowledge exchange through Webinars in response to the pandemic for WSSPs has already been carried out in Brazil, Peru and Bolivia. These webinars are part of the ongoing GIZ activities. AKUTs Latin American experiences have inspired our Kampala office. The African continent has been able to benefit from these webinars too thanks to the cooperation between GWP (German Water Partnership), AfWA (African Water Association) and BMZ (Bundesministerium für wirtschaftliche Zusammenarbeit und Entwicklung).

The webinars aim to present concrete measures and good practices in the face of the Covid-19 pandemic in a practical way. Speakers from WSSPs present their practical experience and through the final question and answer session a beneficial exchange of knowledge is achieved between all participants of the webinar. Some sessions have had simultaneous translation on two channels for the presentations of foreigners. The sessions are recorded and participants receive a draft pandemic response plan document along with the presentations made so that knowledge and lessons learned can be disseminated.

Our initiative has brought the necessary tools for WSSPs to respond effectively to the pandemic, protecting their employees and ensuring the continuity of their services. The success of these webinars is a result from  close cooperation between all parties in the sector. We hope that the high level of motivation and cooperation shown will lead to a rapid response in the water and sanitation sector to the challenge of the pandemic globally.

For further information on Webinars and support in this matter contact: Romas Radtke.

In the presence of the Secretary General for the East African Community (EAC), Liberat Mfumukeko, the starting signal for an integrated water resources management programme in the Lake Victoria catchment area was given on 14 February 2020 in Kisumu, Kenya. The project, coordinated by the Lake Victoria Basin Commission (LVBC), is funded by the German Federal Ministry for Economic Cooperation and Development (BMZ) and the EU.

A joint venture of the companies Consulting Engineers Salzgitter (CES), AKUT Umweltschutz Ingenieure Burkard und Partner and MIBP Consulting Engineers as Project Implementation Consultant (PIC) was commissioned to implement Lot 2 of this programme. In this context, AKUT is responsible for the management of the High Priority Investment (HPI) “Kampala Nakivubo Channel”. The Kreditanstalt für Wiederaufbau (KfW) is responsible for the contract.

Expectations for the multisectoral project with a total volume of EUR 31.9 million (duration until February 2023) are high because the development of Lake Victoria, the second largest freshwater reservoir in the world, is highly alarming in terms of water quality, biodiversity and climate change impacts. Locating the project under the umbrella of the multilateral EAC supports regional cooperation in the region. By developing a “Water Framework Directive” – here following the European approach – the programme aims to reverse the recent negative trend and instead achieve “significant improvements” in water quality. More than 45 million people will benefit from this. To this end, new regulatory standards for discharge parameters are to be developed. In four “High Priority Investment Projects” in Kisumu (Kenya), Kampala (Uganda), Mwanza (Tanzania) and Kigali (Rwanda) concrete measures are planned which promise a considerable reduction of inflowing COD, nutrient and pollutant loads into the lake. One goal is also to develop new site-specific solutions/ technologies on a model basis, which can be implemented in the medium term at other locations in the Lake Victoria catchment area.

AKUT will focus on planning and implementing measures around the Nakivubo Channel, the largest discharger from the Kampala metropolitan region into the Inner Murchison Bay of Lake Victoria. In this context, a feasibility study for a constructed wetland for the treatment of 45,000 m³/day (both sewer water and sewage treatment plant effluent) will be examined and updated. Other variants and process combinations are also being examined in order to implement selected solutions in the next step.

In February 2020 AKUT opened a new branch office in Kampala, Uganda. Since 2005, AKUT has been continuously present with various projects in East and South Africa. With the office in Kampala, AKUT now has its first independent presence on the African continent. This is in connection with an expansion of the activities in the East African region. Our many years of experience in advising water and wastewater utilities are also in increasing demand in East Africa.

The expertise of AKUT lies in the development of locally adapted technological concepts (constructed wetlands, retention soil filters, small wastewater treatment plants, clarification ponds, SBR systems, novel sanitation systems ECOSAN, water loss reduction, measures for surface water remediation, renaturation, biogas plants, renewable energies, agricultural irrigation, multisectoral Nexus programmes) as well as in institutional consulting (development cooperation, SDG achievement, consulting on water tariff systems, capacity building, support in organisational development, social environment management, etc.). AKUT acts in a network with international and local partners.

At this year’s AfWA ICE 2020 (African Water Association International Congress and Exhibition) from 24th to 27th February in Kampala, AKUT can be found on the joint stand of the German Water Partnership (GWP) in Hall 1, B7-B8 & C14-C15. We are looking forward to your visit.

Contact: Romas Radtke

Press release: Programme-Launch.pdf

Development of a wastewater switch for the energy-efficient selective partial flow treatment of highly concentrated wastewater (ESTA) at municipal wastewater treatment plants

The research association ESTA is a merger of AKUT Umweltschutz Ingenieure Burkard und Partner, the Technical University of Berlin, FG Siedlungswasserwirtschaft and LAR Process Analysers AG. The aim was the development of an intelligent wastewater switch in the inflow of municipal sewage treatment plants for the separation of highly charged inflows and energy recovery by means of anaerobic treatment. The joint project “ESTA (FKZ 02WQ1382A-C)” was funded by the Federal Ministry of Education and Research (BMBF) within the framework of the SME-innovativ funding initiative.
As a result, peak inflow concentrations could be identified and evaluated with a time resolution of 6 minutes with regard to height and frequency in order to activate the wastewater diverter.
A successful operation of the wastewater switch and the anaerobic test reactor was possible despite the low peak concentrations and the low number of shock loads on the investigated wastewater treatment plant in combination with excess sludge. The simulation of the wastewater treatment plant showed that, despite the removal of the highly charged wastewater fraction and despite changes in the C:N ratio, the statutory monitoring values can be complied with under the underlying conditions (in particular the low ammonium inflow values). A maximum degree of electrical self-sufficiency of 75 % could be achieved.
A central component of the project was the construction and operation of a test plant at the Baruth (Brandenburg) sewage treatment plant, which was planned and installed in coordination with the project partners TU Berlin and AKUT. The project partner LAR was mainly responsible for the development of an adapted online analysis technology. Project start was 01.10.2016, project end was 31.03.2019.
With the help of the TOC-Online monitor a mechanism was controlled, which feeds inlet water of the sewage treatment plant to an anaerobic reactor from an adjustable threshold concentration. Both the analysed feed concentrations, the volume flows and loads fed into the reactor and the biogas produced in the reactor were evaluated.
Due to the implementation of the TOC online monitor on a trailer, the measuring equipment is now also available for mobile use. Measurement campaigns at other sewage treatment plants and at two industrial sites prove the operational capability. The basic load could be clearly determined and the concentration peaks could be evaluated with regard to height and frequency. It was possible to define threshold values in concentration and volume of an impact load which makes the investigation of a general conversion of the process with separate anaerobic sludge treatment useful.
“Although the Baruth wastewater treatment plant under investigation with the evaluated impact loads is below the threshold values determined and a further investigation does not appear to be appropriate here, the results of the other sites investigated certainly show potential”, explains project coordinator Dipl. Ing. Thilo Burkard (AKUT).
The participating project partners are accordingly optimistic that the new concept can be applied to new construction and conversion of wastewater treatment plants. A measurement campaign with the mobile measuring device is therefore planned for other wastewater treatment plants.

Further information: Thilo Burkard

Thousands of canals run through the cities in China. In the shallow estuaries of the major rivers, they have traditionally served as traffic routes navigable by barges. With rapid and extremely dense development, the drainage of water became increasingly important. However, this was accompanied by ever-increasing pollution. Hydraulically overloaded sewers and high material loads in rainwater runoff today lead to excessive pollution of surface waters. This has a bad effect on their oxygen balance, which leads to serious odour nuisance, especially in the warm season.

Since the government declared the remediation of these waters to be a central task for all municipalities, many technologies have been tested. In most cases, however, success has not been achieved. Obviously, the problem could not be solved by internal measures in the waters alone. In two cases, retention soil filters were now used, which are suitable for the short-term absorption of high hydraulic loads from the combined sewer and stormwater system and thus for treatment before overflowing into the sewer.

Within the framework of the BMBF-funded KEYS joint project entitled “Pioneering technologies for the sustainable management of urban watersheds as a key factor for the successful implementation of the “sponge city” concept”, the effect of these systems is to be demonstrated and investigated in parallel. Retention soil filters were developed in Germany and represent the key technology in this country for both centralised and decentralised treatment of rainwater and combined sewer overflows.

The engineers of AKUT, who have been working in China as consultants for 10 years, are aware that German technology cannot always be transferred one to one abroad. In particular, the data basis for optimal dimensioning is often missing there. In cooperation with the project partners, the prerequisites are now being created. During our visit in December 2019, the sampling locations for the planned measurement campaigns in 2020 were examined and operational data were obtained. The installation of online probes and rain recorders was prepared.

The two demonstration sites, each with 3 000 m² retention filter area, are located in Suzhou, Jiangsu Province. While the first retention soil filter at the Zhujing Channel has been in operation since 2018, the second filter at the Hongshuanglou Channel was not completed until winter 2019.

In contrast to the more water-rich regions, these soil filters will also be used in arid climates such as Beijing. A multifunctional use of the soil filters is being tested for this purpose. This means that in dry weather, the available filter area will be used for direct treatment of surface water. This protects the plant filters from drying out and simultaneously leads to an increased cleaning effect.

The joint project is led by the Institute for Sanitary Engineering of the Leibniz University of Hannover (ISAH) and funded by the Federal Ministry of Education and Research for 3 years within the framework of the funding measure “CLIENT II – International Partnerships for Sustainable Innovations”.

Photo: Till Ermisch (AKUT) interviews Ying ZHANG from Suzhou DeHua Eco Technology Ltd. about the discharge points at the restored Hongshuanglou Channel.

Presentation: IE expo China 2021

In the European joint project AquaNES, various combinations of nature based and technical systems were investigated for their suitability for wastewater treatment from 2016 to 2019. The results were described in a handout for planners and operators describing such and comparable systems. The recommendations show the potentials and reasonable applications of such combinations.

The first part of the document deals with soil filters as part of combined systems and describes possible combinations with technical pre- and post-treatment. The different possible applications of constructed wetlands as primary, secondary or tertiary treatment as well as dual use for combined sewer overflows and as a tertiary treatment stage are highlighted. Important design parameters, in particular the German code of practice DWA A-262 (2017) for the dimensioning, construction and operation of constructed wetlands for municipal wastewater treatment are summarized here and combined with the results from the demonstration sites and the experience of the authors.

In the second part, the five AquaNES sites in Greece, Germany, and Great Britain, their different applications, design and operation data, and monitoring results are presented. The two Greek sites, the Antiparos and Thirasia WWTPs, are both located on tourist-oriented islands in the Aegean Sea. The solution at Antiparos focused on creating a robust, nature-based system that could handle fluctuating hydraulic and organic loads and meet the Greek standard of water reuse for irrigation. At Thirasia, a soil filter was integrated into a number of different engineering processes. Here, photocatalysis via TiO2 was also experimented with and downstream membrane filtration was tested. In Germany, an innovative retention soil filter was constructed in Rheinbach (Erftverband) for the combined use as a fourth treatment stage and for treating combined sewer overflows. At the Schönerlinde wastewater treatment plant, the combination consisted of an ozone plant and a downstream soil filter. Here, the retention of organic micropollutants such as pharmaceutical residues and metabolites in the effluent of the wastewater treatment plant was also demonstrated. Finally, the effectiveness of soil filters with reactive filter material made from blast furnace slag was investigated in long-term operation at the Packington site (UK).

Further information: Heribert Rustige

Download: Report