@article{CheenakulaGriebelMontagetal.2023, author = {Cheenakula, Dheeraja and Griebel, Kai and Montag, David and Gr{\"o}mping, Markus}, title = {Concept development of a mainstream deammonification and comparison with conventional process in terms of energy, performance and economical construction perspectives}, series = {Frontiers in Microbiology}, volume = {14}, journal = {Frontiers in Microbiology}, number = {11155235}, editor = {Huang, Xiaowu}, publisher = {Frontiers}, issn = {1664-302X}, doi = {10.3389/fmicb.2023.1155235}, pages = {1 -- 15}, year = {2023}, abstract = {Deammonification for nitrogen removal in municipal wastewater in temperate and cold climate zones is currently limited to the side stream of municipal wastewater treatment plants (MWWTP). This study developed a conceptual model of a mainstream deammonification plant, designed for 30,000 P.E., considering possible solutions corresponding to the challenging mainstream conditions in Germany. In addition, the energy-saving potential, nitrogen elimination performance and construction-related costs of mainstream deammonification were compared to a conventional plant model, having a single-stage activated sludge process with upstream denitrification. The results revealed that an additional treatment step by combining chemical precipitation and ultra-fine screening is advantageous prior the mainstream deammonification. Hereby chemical oxygen demand (COD) can be reduced by 80\% so that the COD:N ratio can be reduced from 12 to 2.5. Laboratory experiments testing mainstream conditions of temperature (8-20°C), pH (6-9) and COD:N ratio (1-6) showed an achievable volumetric nitrogen removal rate (VNRR) of at least 50 gN/(m3∙d) for various deammonifying sludges from side stream deammonification systems in the state of North Rhine-Westphalia, Germany, where m3 denotes reactor volume. Assuming a retained Norganic content of 0.0035 kgNorg./(P.E.∙d) from the daily loads of N at carbon removal stage and a VNRR of 50 gN/(m3∙d) under mainstream conditions, a resident-specific reactor volume of 0.115 m3/(P.E.) is required for mainstream deammonification. This is in the same order of magnitude as the conventional activated sludge process, i.e., 0.173 m3/(P.E.) for an MWWTP of size class of 4. The conventional plant model yielded a total specific electricity demand of 35 kWh/(P.E.∙a) for the operation of the whole MWWTP and an energy recovery potential of 15.8 kWh/(P.E.∙a) through anaerobic digestion. In contrast, the developed mainstream deammonification model plant would require only a 21.5 kWh/(P.E.∙a) energy demand and result in 24 kWh/(P.E.∙a) energy recovery potential, enabling the mainstream deammonification model plant to be self-sufficient. The retrofitting costs for the implementation of mainstream deammonification in existing conventional MWWTPs are nearly negligible as the existing units like activated sludge reactors, aerators and monitoring technology are reusable. However, the mainstream deammonification must meet the performance requirement of VNRR of about 50 gN/(m3∙d) in this case.}, language = {en} } @article{BienerSasse1993, author = {Biener, Ernst and Sasse, T.}, title = {Construction and rehabilitation of landfill shafts}, series = {Sardinia 93 : Fourth International Landfill Symposium "Barrier systems, environmental aspects, upgrading and remediation, siting, monofills, effects of waste pretreatment, landfilling in developing countries" ; 11 - 15 October 1993, S. Margherita di Pula (Cagliari), Sardinia, Italy ; proceedings / coord. by Thomas H. Christensen ... - Bd. 1}, journal = {Sardinia 93 : Fourth International Landfill Symposium "Barrier systems, environmental aspects, upgrading and remediation, siting, monofills, effects of waste pretreatment, landfilling in developing countries" ; 11 - 15 October 1993, S. Margherita di Pula (Cagliari), Sardinia, Italy ; proceedings / coord. by Thomas H. Christensen ... - Bd. 1}, publisher = {CISA, Environmental Sanitary Engineering Centre}, address = {Cagliari}, pages = {451 -- 460}, year = {1993}, language = {en} } @article{BienerSasse1994, author = {Biener, Ernst and Sasse, T.}, title = {Construction of composite lining systems under unfavourable weather conditions}, series = {Landfilling of waste: barriers / ed. by T. H. Christensen; R. Cossu; R. Stegmann. - 1. Aufl.}, journal = {Landfilling of waste: barriers / ed. by T. H. Christensen; R. Cossu; R. Stegmann. - 1. Aufl.}, publisher = {Spon}, address = {London [u.a.]}, isbn = {0419159908}, pages = {183 -- 200}, year = {1994}, language = {en} } @article{WoliszSchuetzBlankeetal.2017, author = {Wolisz, Henryk and Sch{\"u}tz, Thomas and Blanke, Tobias and Hagenkamp, Markus and Kohrn, Markus and Wesseling, Mark and M{\"u}ller, Dirk}, title = {Cost optimal sizing of smart buildings' energy system components considering changing end-consumer electricity markets}, series = {Energy}, volume = {137}, journal = {Energy}, publisher = {Elsevier}, address = {Amsterdam}, doi = {10.1016/j.energy.2017.06.025}, pages = {715 -- 728}, year = {2017}, language = {en} } @article{Bung2011, author = {Bung, Daniel B.}, title = {Developing flow in skimming flow regime on embankment stepped spillways}, series = {Journal of hydraulic research}, volume = {Vol. 49}, journal = {Journal of hydraulic research}, number = {Iss. 5}, publisher = {Taylor \& Francis}, address = {London}, issn = {1814-2079 (E-Journal); 0022-1686 (Print)}, pages = {639 -- 648}, year = {2011}, language = {en} } @article{ValeroBung2016, author = {Valero, Daniel and Bung, Daniel B.}, title = {Development of the interfacial air layer in the non-aerated region of high-velocity spillway flows: Instabilities growth, entrapped air and influence on the self-aeration onset}, series = {International Journal of Multiphase Flow}, volume = {84}, journal = {International Journal of Multiphase Flow}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0301-9322}, doi = {10.1016/j.ijmultiphaseflow.2016.04.012}, pages = {66 -- 74}, year = {2016}, abstract = {Self-aeration is traditionally explained by the water turbulent boundary layer outer edge intersection with the free surface. This paper presents a discussion on the commonly accepted hypothesis behind the computation of the critical point of self-aeration in spillway flows and a new formulation is proposed based on the existence of a developing air flow over the free surface. Upstream of the inception point of self-aeration, some surface roughening has been often reported in previous studies which consequently implies some entrapped air transport and air-water flows coupling. Such air flow is proven in this study by presenting measured air velocities and computing the air boundary layer thickness for a 1V:2H smooth chute flow. Additionally, the growth rate of free surface waves has been analysed by means of Ultrasonic Sensors measurements, obtaining also the entrapped air concentration. High-speed camera imaging has been used for qualitative study of the flow perturbations.}, language = {en} } @article{ValeroBungCrookston2018, author = {Valero, Daniel and Bung, Daniel B. and Crookston, B.M.}, title = {Energy dissipation of a Type III basin under design and adverse conditions for stepped and smooth spillways}, series = {Journal of Hydraulic Engineering}, volume = {144}, journal = {Journal of Hydraulic Engineering}, number = {7}, publisher = {ASCE}, address = {Reston, Va.}, issn = {0733-9429}, doi = {10.1061/(ASCE)HY.1943-7900.0001482}, year = {2018}, abstract = {New information regarding the influence of a stepped chute on the hydraulic performance of the United States Bureau of Reclamation (Reclamation) Type III hydraulic jump stilling basin is presented for design (steady) and adverse (decreasing tailwater) conditions. Using published experimental data and computational fluid dynamics (CFD) models, this paper presents a detailed comparison between smooth-chute and stepped-chute configurations for chute slopes of 0.8H:1V and 4H:1V and Froude numbers (F) ranging from 3.1 to 9.5 for a Type III basin designed for F = 8. For both stepped and smooth chutes, the relative role of each basin element was quantified, up to the most hydraulic extreme case of jump sweep-out. It was found that, relative to a smooth chute, the turbulence generated by a stepped chute causes a higher maximum velocity decay within the stilling basin, which represents an enhancement of the Type III basin's performance but also a change in the relative role of the basin elements. Results provide insight into the ability of the CFD models [unsteady Reynolds-averaged Navier-Stokes (RANS) equations with renormalization group (RNG) k-ϵ turbulence model and volume-of-fluid (VOF) for free surface tracking] to predict the transient basin flow structure and velocity profiles. Type III basins can perform adequately with a stepped chute despite the effects steps have on the relative role of each basin element. It is concluded that the classic Type III basin design, based upon methodology by reclamation specific to smooth chutes, can be hydraulically improved for the case of stepped chutes for design and adverse flow conditions using the information presented herein.}, language = {en} } @article{KerpenBungValeroetal.2017, author = {Kerpen, Nils B. and Bung, Daniel B. and Valero, Daniel and Schlurmann, Torsten}, title = {Energy dissipation within the wave run-up at stepped revetments}, series = {Journal of Ocean University of China}, volume = {16}, journal = {Journal of Ocean University of China}, number = {4}, publisher = {Springer}, address = {Berlin}, issn = {1993-5021}, doi = {10.1007/s11802-017-3355-z}, pages = {649 -- 654}, year = {2017}, language = {en} } @article{BienerSasse1988, author = {Biener, Ernst and Sasse, T.}, title = {Experience with new techniques in slurry cutoff wall construction}, series = {ISWA 88, proceedings of the 5th International Solid Wastes Conference : September 11 - 16th, 1988, Copenhagen, Denmark / ed. by Lizzi Andersen ... - Vol. 1 : Oral presentations}, journal = {ISWA 88, proceedings of the 5th International Solid Wastes Conference : September 11 - 16th, 1988, Copenhagen, Denmark / ed. by Lizzi Andersen ... - Vol. 1 : Oral presentations}, publisher = {Acad. Press}, address = {London [u.a.]}, isbn = {0-12-058451-4}, pages = {41 -- 46}, year = {1988}, language = {en} } @article{Kirsch2010, author = {Kirsch, Ansgar}, title = {Experimental investigation of the face stability of shallow tunnels in sand}, series = {Acta Geotechnica}, volume = {5}, journal = {Acta Geotechnica}, number = {1}, publisher = {Springer}, address = {Berlin}, issn = {1861-1125}, doi = {10.1007/s11440-010-0110-7}, pages = {43 -- 62}, year = {2010}, abstract = {Various models have been proposed for the prediction of the necessary support pressure at the face of a shallow tunnel. To assess their quality, the collapse of a tunnel face was modelled with small-scale model tests at single gravity. The development of the failure mechanism and the support force at the face in dry sand were investigated. The observed displacement patterns show a negligible influence of overburden on the extent and evolution of the failure zone. The latter is significantly influenced, though, by the initial density of the sand: in dense sand a chimney-wedge-type collapse mechanism developed, which propagated towards the soil surface. Initially, loose sand did not show any discrete collapse mechanism. The necessary support force was neither influenced by the overburden nor the initial density. A comparison with quantitative predictions by several theoretical models showed that the measured necessary support pressure is overestimated by most of the models. Those by Vermeer/Ruse and L{\´e}ca/Dormieux showed the best agreement to the measurements.}, language = {en} } @article{HoettgesFeldhausBrockhausetal.1992, author = {H{\"o}ttges, J{\"o}rg and Feldhaus, R. and Brockhaus, T. and Rouv{\´e}, Gerhard}, title = {Finite Element Simulation of Flow and Pollution Transport applied to a Part of the River Rhine / Feldhaus, R.; J. H{\"o}ttges, T. Brockhaus; G. Rouv{\´e}}, series = {Hydraulic and environmental modelling : proceedings of the Second International Conference on Hydraulic and Environmental Modelling of Coastal, Estuarine, and River Waters / [IAHR-AIRH]. Ed. by R. A. Falconer}, journal = {Hydraulic and environmental modelling : proceedings of the Second International Conference on Hydraulic and Environmental Modelling of Coastal, Estuarine, and River Waters / [IAHR-AIRH]. Ed. by R. A. Falconer}, publisher = {Ashgate}, address = {Aldershot, Hants, UK [u.a.]}, year = {1992}, language = {en} } @article{KerresGredigkHoffmannJatheetal.2020, author = {Kerres, Karsten and Gredigk-Hoffmann, Sylvia and Jathe, R{\"u}diger and Orlik, Stefan and Sariyildiz, Mustafa and Schmidt, Torsten and Sympher, Klaus-Jochen and Uhlenbroch, Adrian}, title = {Future approaches for sewer system condition assessment}, series = {Water Practice \& Technology}, journal = {Water Practice \& Technology}, number = {15 (2)}, publisher = {IWA Publishing}, address = {London}, issn = {1751-231X}, doi = {10.2166/wpt.2020.027}, pages = {386 -- 393}, year = {2020}, abstract = {Different analytical approaches exist to describe the structural substance or wear reserve of sewer systems. The aim is to convert engineering assessments of often complex defect patterns into computational algorithms and determine a substance class for a sewer section or manhole. This analytically determined information is essential for strategic rehabilitation planning processes up to network level, as it corresponds to the most appropriate rehabilitation type and can thus provide decision-making support. Current calculation methods differ clearly from each other in parts, so that substance classes determined by the different approaches are only partially comparable with each other. The objective of the German R\&D cooperation project 'SubKanS' is to develop a methodology for classifying the specific defect patterns resulting from the interaction of all the individual defects, and their severities and locations. The methodology takes into account the structural substance of sewer sections and manholes, based on real data and theoretical considerations analogous to the condition classification of individual defects. The result is a catalogue of defect patterns and characteristics, as well as associated structural substance classifications of sewer systems (substance classes). The methodology for sewer system substance classification is developed so that the classification of individual defects can be transferred into a substance class of the sewer section or manhole, eventually taking into account further information (e.g. pipe material, nominal diameter, etc.). The result is a validated methodology for automated sewer system substance classification.}, language = {en} } @article{BienerBoykenSasseetal.1999, author = {Biener, Ernst and Boyken, P. and Sasse, T. and Arnold, J.}, title = {Geotechnical aspects of the construction of the integrated harbour sludge management system in Bremen-Seehausen / P. Boyken ; E. Biener ; T. Sasse ; J. Arnold}, series = {Geotechnical engineering for transportation infrastructure : proceedings of the twelfth European Conference on Soil Mechanics and Geotechnical Engineering, Amsterdam, Netherlands, 7 - 10 June 1999 ; theory and practice, planning and design, construction and maintenance. - Vol. 2}, journal = {Geotechnical engineering for transportation infrastructure : proceedings of the twelfth European Conference on Soil Mechanics and Geotechnical Engineering, Amsterdam, Netherlands, 7 - 10 June 1999 ; theory and practice, planning and design, construction and maintenance. - Vol. 2}, publisher = {Balkema}, address = {Rotterdam}, isbn = {90-5809-049-3}, pages = {909 -- 914}, year = {1999}, language = {en} } @article{ErpicumCrookstonBombardellietal.2021, author = {Erpicum, Sebastien and Crookston, Brian M. and Bombardelli, Fabian and Bung, Daniel B. and Felder, Stefan and Mulligan, Sean and Oertel, Mario and Palermo, Michele}, title = {Hydraulic structures engineering: An evolving science in a changing world}, series = {Wires Water}, volume = {8}, journal = {Wires Water}, number = {2}, publisher = {Wiley}, address = {Weinheim}, issn = {2049-1948}, doi = {10.1002/wat2.1505}, year = {2021}, language = {en} } @article{KuhnhenneRegerPyschnyetal.2020, author = {Kuhnhenne, Markus and Reger, Vitali and Pyschny, Dominik and D{\"o}ring, Bernd}, title = {Influence of airtightness of steel sandwich panel joints on heat losses}, series = {E3S Web of Conferences 12th Nordic Symposium on Building Physics (NSB 2020)}, volume = {172}, journal = {E3S Web of Conferences 12th Nordic Symposium on Building Physics (NSB 2020)}, number = {Art. 05008}, publisher = {EDP Sciences}, address = {Les Ulis}, doi = {10.1051/e3sconf/202017205008}, pages = {6}, year = {2020}, abstract = {Energy saving ordinances requires that buildings must be designed in such a way that the heat transfer surface including the joints is permanently air impermeable. The prefabricated roof and wall panels in lightweight steel constructions are airtight in the area of the steel covering layers. The sealing of the panel joints contributes to fulfil the comprehensive requirements for an airtight building envelope. To improve the airtightness of steel sandwich panels, additional sealing tapes can be installed in the panel joint. The influence of these sealing tapes was evaluated by measurements carried out by the RWTH Aachen University - Sustainable Metal Building Envelopes. Different installation situations were evaluated by carrying out airtightness tests for different joint distances. In addition, the influence on the heat transfer coefficient was also evaluated using the Finite Element Method (FEM). The combination of obtained air volume flow and transmission losses enables to create an "effective heat transfer coefficient" due to transmission and infiltration. This summarizes both effects in one value and is particularly helpful for approximate calculations on energy efficiency.}, language = {en} } @article{OertelBung2012, author = {Oertel, Mario and Bung, Daniel B.}, title = {Initial stage of two-dimensional dam-break waves: laboratory versus VOF}, series = {Journal of hydraulic research}, volume = {50}, journal = {Journal of hydraulic research}, number = {1}, publisher = {Taylor \& Francis}, address = {London}, issn = {1814-2079 (E-Journal); 0022-1686 (Print)}, doi = {10.1080/00221686.2011.639981}, pages = {89 -- 97}, year = {2012}, abstract = {Since several decades, dam-break waves have been of main research interest. Mathematical approaches have been developed by analytical, physical and numerical models within the past 120 years. During the past 10 years, the number of research investigations has increased due to improved measurement techniques as well as significantly increased computer memories and performances. In this context, the present research deals with the initial stage of two-dimensional dam-break waves by comparing physical and numerical model results as well as analytical approaches. High-speed images and resulting particle image velocimetry calculations are thereby compared with the numerical volume-of-fluid (VOF) method, included in the commercial code FLOW-3D. Wave profiles and drag forces on placed obstacles are analysed in detail. Generally, a good agreement between the laboratory and VOF results is found.}, language = {en} } @article{BienerBoykenSasse1997, author = {Biener, Ernst and Boyken, P. and Sasse, T.}, title = {Integrated dredged material management system of Bremen-Seehausen}, series = {Sardinia 97 : proceedings ; [13 - 17 October 1997, S. Margherita di Pula - Cagliari, Sardinia, Italy] / Sixth International Landfill Symposium. Ed.: Thomas H. Christensen... - Bd. 5 : Landfill regulations, waste characteristics, landfilling in middle and lower income countries, industrial wastes and monolandfills}, journal = {Sardinia 97 : proceedings ; [13 - 17 October 1997, S. Margherita di Pula - Cagliari, Sardinia, Italy] / Sixth International Landfill Symposium. Ed.: Thomas H. Christensen... - Bd. 5 : Landfill regulations, waste characteristics, landfilling in middle and lower income countries, industrial wastes and monolandfills}, publisher = {CISA, Environmental Sanitary Engineering Centre}, address = {Cagliari}, pages = {497 -- 502}, year = {1997}, language = {en} } @article{HoettgesArnoldRouve1994, author = {H{\"o}ttges, J{\"o}rg and Arnold, Uwe and Rouv{\´e}, Gerhard}, title = {Measurement of transverse mixing using digital image acquisition}, series = {Mixing and transport in the environment : a memorial volume for Catherine M. Allen (1954-1991) / ed. by Keith J. Beven}, journal = {Mixing and transport in the environment : a memorial volume for Catherine M. Allen (1954-1991) / ed. by Keith J. Beven}, publisher = {Wiley}, address = {Chichester [u.a.]}, isbn = {0471941425}, pages = {XVI, 458 S., [8] Bl : Ill. (z.T. farb.), graph. Da}, year = {1994}, language = {en} } @article{LeandroBungCarvalho2014, author = {Leandro, J. and Bung, Daniel B. and Carvalho, R.}, title = {Measuring void fraction and velocity fields of a stepped spillway for skimming flow using non-intrusive methods}, series = {Experiments in fluids}, journal = {Experiments in fluids}, number = {55}, publisher = {Springer Nature}, address = {Heidelberg}, issn = {0723-4864 (Print) ; 1432-1114 (Online)}, doi = {10.1007/s00348-014-1732-6}, pages = {Art. 1732}, year = {2014}, language = {en} } @article{BlankeHagenkampDoeringetal.2021, author = {Blanke, Tobias and Hagenkamp, Markus and D{\"o}ring, Bernd and G{\"o}ttsche, Joachim and Reger, Vitali and Kuhnhenne, Markus}, title = {Net-exergetic, hydraulic and thermal optimization of coaxial heat exchangers using fixed flow conditions instead of fixed flow rates}, series = {Geothermal Energy}, volume = {9}, journal = {Geothermal Energy}, number = {Article number: 19}, publisher = {Springer}, address = {Berlin}, issn = {2195-9706}, doi = {10.1186/s40517-021-00201-3}, pages = {23 Seiten}, year = {2021}, abstract = {Previous studies optimized the dimensions of coaxial heat exchangers using constant mass fow rates as a boundary condition. They show a thermal optimal circular ring width of nearly zero. Hydraulically optimal is an inner to outer pipe radius ratio of 0.65 for turbulent and 0.68 for laminar fow types. In contrast, in this study, fow conditions in the circular ring are kept constant (a set of fxed Reynolds numbers) during optimization. This approach ensures fxed fow conditions and prevents inappropriately high or low mass fow rates. The optimization is carried out for three objectives: Maximum energy gain, minimum hydraulic efort and eventually optimum net-exergy balance. The optimization changes the inner pipe radius and mass fow rate but not the Reynolds number of the circular ring. The thermal calculations base on Hellstr{\"o}m's borehole resistance and the hydraulic optimization on individually calculated linear loss of head coefcients. Increasing the inner pipe radius results in decreased hydraulic losses in the inner pipe but increased losses in the circular ring. The net-exergy diference is a key performance indicator and combines thermal and hydraulic calculations. It is the difference between thermal exergy fux and hydraulic efort. The Reynolds number in the circular ring is instead of the mass fow rate constant during all optimizations. The result from a thermal perspective is an optimal width of the circular ring of nearly zero. The hydraulically optimal inner pipe radius is 54\% of the outer pipe radius for laminar fow and 60\% for turbulent fow scenarios. Net-exergetic optimization shows a predominant infuence of hydraulic losses, especially for small temperature gains. The exact result depends on the earth's thermal properties and the fow type. Conclusively, coaxial geothermal probes' design should focus on the hydraulic optimum and take the thermal optimum as a secondary criterion due to the dominating hydraulics.}, language = {en} }