bluuebunny/crossref_metadata_2025 huggingface dataset:
Application of models in water management in the Netherlands: past, present and future
Authors: van Waveren R. H.
Published: May 2018

For about 20 years models have been used on a large scale in the water management of The Netherlands. Today models are indispensable in modern water management. However, while on one hand the application of models in water management still increases, on the other hand the appreciation of policy makers for models decreases, especially in the Dutch national policy. One has to look very carefully to recognise the policy analysis by models in the policy documents, although the number of used models and the number of calculations was larger than ever before. Summarised it may be stated that the application of models is facing some serious problems. Especially the efficiency must increase. Together with the coming, new questions in water management, the involved participants in integrated water management are forced to join forces in the development and application of models. Therefore in The Netherlands a Standard Framework discussion started between the involved participators. The first results are very promising. Looking at the future it can be concluded that the next generation of models to be built for the fifth National Policy Document on Water Management, will not just be a model system of the national government, but a system of all involved participants in Dutch water management.
Analysis and design of suitable model structures for activated sludge tanks with circulating flow
Authors: Alex J. , Tschepetzki R. , Jumar U. , Obenaus F. , Rosenwinkel K.-H.
Published: May 2018

Activated sludge models are widely used for planning and optimisation of wastewater treatment plants and on line applications are under development to support the operation of complex treatment plants. A proper model is crucial for all of these applications. The task of parameter calibration is focused in several papers and applications. An essential precondition for this task is an appropriately defined model structure, which is often given much less attention. Different model structures for a large scale treatment plant with circulation flow are discussed in this paper. A more systematic method to derive a suitable model structure is applied to this case. Results of a numerical hydraulic model are used for this purpose. The importance of these efforts are proven by a high sensitivity of the simulation results with respect to the selection of the model structure and the hydraulic conditions. Finally it is shown, that model calibration was possible only by adjusting to the hydraulic behaviour and without any changes of biological parameters.
Rational transfer function models for nitrifying trickling filters
Authors: Wik T.
Published: May 2018

An important step towards optimization and control of wastewater treatment plants is the development of dynamic models and efficient methods of simulation. Using standard simplifying assumptions, non-rational transfer function models describing the fast dynamics of nitrifying trickling filters, are derived. With a method based on the location of their singularities, it is shown how low order rational transfer functions can approximate the non-rational ones. These transfer functions can be used in efficient simulation routines and in standard methods of controller design. Effluent concentrations from trace substance pulse response experiments and an experiment with varying flow and varying influent ammonium concentration carried out on a large pilot plant NTF show close agreement with simulated effluent concentrations using the rational transfer functions.
DELFTMDD: A tool for integration of independent models in a decision support system
Authors: Gijsbers P. J. A.
Published: May 2018

The need for integrated analysis poses a request for integration of computer models, paying extra attention to interfaces, data management and user interaction. Sector wide standardization using data dictionaries and data exchange formats can be a great help in streamlining data exchange. However, this type of standardization can have some drawbacks for a generic framework for model integration. Another concept, called Model Data Dictionary (MDD), has been developed as an alternative for proper data management. The concept is a variant on the federated database concept, a concept where local databases maintain their autonomy, while an interconnection database provides a link for sharing data. The MDD is based on a highly generic data model for geographic referenced objects, which if needed facilitates mapping of the sector wide data dictionary. External interfaces provide, in combination with a data format mapping component, a link to SQL-based data sources and model specific databases. A generic Object Data Editor (ODE), linked to the MDD, has been proposed for provision of a common data editing facility for mathematical models. A test version of the combined MDD/ODE-concept has shown the applicability for integration of all kinds of geographic object oriented mathematical models (both simulation and optimization).
Integrated water quality and environmental cost-benefit modelling for the management of the River Tame
Authors: Crabtree Bob , Hickman Matt , Martin Dave
Published: May 2018

In the UK, the River Tame catchment covers an area of about 1,400 km2 and forms the northern portion of the Birmingham Conurbation. In the 1960s, wet weather conditions in Birmingham could result in the total depletion of oxygen in the River Trent below the Tame confluence. Construction of a system of purification lakes at Lea Marston, below the major polluting discharges, was completed in the early 1980s. Today, the operation of the Lea Marston Lakes significantly improves the quality of the Tame. However, wet weather pollution episodes in the Tame continues to have a severe impact on water quality in the Trent and put major fisheries at risk. This paper reports on the outcome of an integrated environmental impact and cost-benefit assessment modelling study into the future strategic management of the Lea Marston Lakes. The study demonstrated that the Lea Marston Lakes provide an economically justifiable method for reducing the water quality impact of the Birmingham conurbation and as a result will continue to be operated.
Cost-effective pre-treatment of wastewater
Authors: El-Gohary Fatma A. , Nasr Fayza A.
Published: May 2018

The implementation of low-cost, simple mitigation measures is required for the timely control and sustainable management of pollution problems in developing countries. Recently, the use of anaerobic systems for wastewater treatment has received a growing attention since they represent an alternative cost-effective approach for removal of pollutants. Therefore, evaluation of the performance of an Upflow Anaerobic Sludge Blanket Reactor, as a pre-treatment step for industrial as well as domestic wastewater was the subject of this study. The results obtained showed that the performance of one-stage UASB at 8hrs hydraulic retention time (HRT) for domestic wastewater treatment was quite satisfactory. CODtot and BODtot removal values averaged 77% and 83%. Comparison of the performance of a one-stage versus two-stage reactor, having the same volume and operated at the same HRT (8 hr) and biomass concentration indicated an improvement in the quality of the two-stage effluent. With regard to the wastewater discharged from a potato-chips factory, the use of one-stage UASB at a detention time of 18hrs and an average organic load of 2.9 kg BOD/m3/d gave good results. Average residual values of COD, BOD, TSS and oil and grease in the treated effluent were 650, 342, 203 and 63 mg/l, respectively. Operation of a two-stage pilot-scale UASB indicated better performance as expressed by COD and BOD removal values.
On the modelling and simulation of a BNR activated sludge process based on distributed parameter approach
Authors: Lee T. T. , Wang F. Y. , Newell R. B.
Published: May 2018

A computational algorithm, based on an orthogonal collocation approach is developed to simulate a BNR activated sludge process consisting of anaerobic, anoxic and aerobic zones in a back-to-back scheme. The hydraulic model employed in this study considers backmixing or intermixing, which can represent the actual process more accurately than the idealised flow schemes commonly employed for modelling and/or design of the activated sludge bioreactor. The kinetic model of the International Association on Water Quality (IAWQ) - Activated Sludge Model No. 2 (ASM No. 2) was reduced to submodels representing the anaerobic, anoxic and aerobic zones. Validation of simulated results against pilot-scale experimental data suggested that the new computational algorithm is able to predict the behaviour of components of interest reasonably well despite uncertainties with processes and parameters related to phosphorus accumulating organisms. Predicted transient properties may be gainfully employed for improvement to the operation and control of the process.
Retrofitting of intermittent decanted extended aeration (IDEA) plant for enhanced biological phosphorus removal
Authors: Chong Robert W. , Flinders Alan , Krogh Carmel , Battye-Smith Warwick , Emmanual Angelo
Published: May 2018

The Intermittent Decanted Extended Aeration (IDEA) process developed over 30 years ago by the then NSW Department of Public Works (DPW) provided substantial cost savings over the continuous activated sludge process. This is achieved by combining the process of aeration and sludge settlement in a single tank.

The first IDEA plant was constructed at Adelong, NSW, in 1965. Since then over 100 plants have been built by DPW and Department of Land and Water Conservation (DLWC) for communities of a few hundred people to large regional centres serving over 50,000 people.

This paper presents the latest development of incorporating enhanced biological phosphorus removal (EBPR) in the IDEA process. The retrofitting of 3 IDEA plants (capacity ranging from 4000 to 55000 persons) for EBPR is discussed. Different innovative and low cost solutions of incorporating conventional EBPR technology to the single tank IDEA plant are presented. Operational data including plant loading, effluent quality and sludge handling are also discussed.
Advances in Treatment Processes to Solve Off-Flavor Problems in Drinking Water
Authors: McGuire M. J.
Published: May 2018

There have been significant advances in the development and application of treatment processes to control off-flavor problems in drinking water in the past few years. This paper updates two major treatment process summaries that appeared in 1988 and 1995. The paper also puts the efficiencies of the treatment processes in perspective by using the drinking water flavor wheel as a reference point. Removal or control of classes of off-flavor problems are described in relation to the categories on the wheel. Specifically, processes such as oxidation, adsorption, biological treatment and membranes are described. The recent literature is reviewed and advances in treatment are identified. A new treatment process for controlling nitrification in distribution systems is introduced which has the potential to dramatically reduce the problems of chlorinous odor complaints from customers.
Impact of metals bioleaching on the nutrient value of biological nutrient removal biosolids
Authors: Shanableh Abdallah , Ginige Pushpa
Published: May 2018

The biosolids industry in Australia is evolving around the beneficial use of biosolids as a resource. Phosphorus rich biosolids from biological nutrient removal (BNR) facilities are highly desirable for land application. However, the accumulation of toxic heavy metals and industrial organic contaminants may render the biosolids unsuitable for land application. The presence of toxic heavy metals has been identified by Local Authorities in Australia as a major constraint limiting the beneficial use of biosolids. The potential of off-site contamination due to the migration of nutrients is also a major concern especially when applying biosolids to acidic agricultural land. Accordingly, the relevant environment protection and conservation agencies are involved in either developing or finalising guidelines to control the beneficial use of biosolids products.

Metals bioleaching is a process achieved through bio-acidification. Bio-acidification of biosolids prior to land application can be used to dissolve and remove a significant fraction of the heavy metals content of the product. However, the process also reduces the nutrients content of the resource. Bio-acidification of Loganholme (Queensland) BNR biosolids dissolved 76% of the total phosphorus and 38% of the TKN. The heavy metals solubilisation results reached 50% for Cr, 79% for Ni, 45% for Zn, 24% for Cu, 30% for Cd, and 82% for Pb.
Relationship Between the Maximum Standing Crop of Musty-Odor Producing Algae and Nutrient Concentrations in the Southern Basin Water of Lake Biwa
Authors: Nakanishi M. , Hoson T. , Inoue Y. , Yagi M.
Published: May 2018

In order to make clear the growth characteristics of musty-odor producing algae (Oscillatoria tenuis, Phormidium tenue and Anabaena macrospora), we examined the correlation between the maximum growth number (MGN) of each alga and nutrient concentrations, with the unialgal culture method using a 0.45μm pore size membrane-filtered lake water. We found that the MGN of Lake Biwa water was limited by soluble phosphorus concentration.

In order to verify the results, we examined out the relation between the maximum standing crop (MSC) of musty-odor producing algae in the southern basin of Lake Biwa and nutrient concentrations of our 12-year (1983-1994) observation data. The MSC of P. tenue showed a positive correlation with the N:P ratio. On the other hand, The MSC of O. tenuis showed a strong positive correlation with the phosphorus concentration, and a positive correlation with the iron and soluble phosphorus concentration, but a strong negative correlation with the N:P ratio. When the phosphorus concentration is over 0.030 mg/l, O. tenuis will probably be over 10 filaments/mL. The optimum N:P ratio range was 10 to 20.
Biological nutrient removal efficiency in treatment of saline wastewater
Authors: Intrasungkha Nugul , Keller Jürg , Blackall Linda L.
Published: May 2018

There is very little known about the effectiveness of wastewater treatment systems for saline wastewater generated by seafood processing industries, aquaculture and tourism activities. In particular, the effect of salinity on nitrogen and phosphorus removal in wastewater treatment processes is not well understood. Therefore we devised experiments to examine the treatment of highly saline wastewater, by using artificial seafood processing wastewater, for removal of nitrogen and phosphorus. Lab scale sequencing batch reactors (SBR) were initially operated at low, and then at increasing salt levels, to determine the overall effects of salinity on the nutrient removal performance. The microbial populations during these experiments were monitored to determine the specific effect of salinity on the various bacterial groups responsible for nutrient removal. The methods used were whole cell probing with fluorescently labelled RNA-directed oligonucleotide probes. Experimental data showed that the SBRs achieved good biological nutrient removal (BNR) when salinity levels in the influent were low (0.03% to 0.2% NaCl) but showed difficulties with biological phosphorus removal at salinity levels of 0.5%. It was found that there was a dominance of Gram-positive bacteria with a high mol% G+C in their DNA in the SBR treating wastewater with NaCl at 0.03% to 0.2%. The addition of acetate to improve BNR performance increased the proportion of bacteria from the beta Proteobacterial subclass.
Estimation of Dispersion Number in Waste Stabilization Ponds
Authors: Esen Ismail I. , Al-Shayji Yousif
Published: May 2018

The hydraulic behavior of waste stabilization ponds is rather complex, and the flow in ponds can at best be described as dispersed flow. The dispersion characteristics of existing ponds can be determined by tracer studies, but it is impractical to perform tracer studies under every possible hydraulic condition. On the other hand, in the assessment of pond performance, first-order kinetics for BOD removal and bacterial die-off have been generally adopted. In this study, a nonlinear least-squares scheme will be presented for the simultaneous estimation of the decay constant and the dispersion number from the well known Wehner-Wilhelm equation which describes the reduction in pollutant concentration in a chemical reactor exhibiting first-order kinetics and non-ideal mixing conditions. As an example, the procedure developed will be applied to actual BOD data obtained from model facultative ponds in Kuwait.
Monitoring sulfate-reducing bacteria in heterotrophic biofilms
Authors: Power M. E. , Araujo J. C. , van der Meer J. R. , Harms H. , Wanner O.
Published: May 2018

To a laboratory reactor, in which heterotrophic biofilms were grown on stainless steel coupons under aerobic conditions, sulfate-reducing bacteria (SRB) were added in order to elucidate whether and how these microorganisms were going to establish themselves in the biofilm. Polymerase chain reaction for the dissimilatory sulfite reductase gene and in situ hybridization with probes directed against 16S ribosomal RNA were used to detect the SRB in the biofilm. Both methods proved to be suitable tools for monitoring the SRB in these experiments, which lasted seven days. In a first series of experiments, in which the SRB were added after a biofilm had already developed, the SRB could be detected only one day after addition. No evidence was found that the SRB penetrated the biofilm and established themselves in the anaerobic niches which were present. In a second series of experiments, in which the SRB were inoculated together with a seed of aerobic heterotrophic microorganisms, the SRB were present in the biofilm over the whole biofilm depth and for the duration of the experiment. The study suggests that colonization of the steel coupons by the SRB added to the bulk fluid is hampered by the already developed biofilm, even though the heterogeneous biofilm structure and anaerobic zones in the biofilm depth offer the possibility for the SRB to penetrate and establish themselves.
The role of (bio)surfactant sorption in promoting the bioavailability of nutrients localized at the solid-water interface
Authors: Jordan Ryan N. , Nichols Eric P. , Cunningham Alfred B.
Published: May 2018

Bioavailability is herein defined as the accessibility of a substrate by a microorganism. Further, bioavailability is governed by (1) the substrate concentration that the cell membrane “sees,” (i.e., the “directly bioavailable” pool) as well as (2) the rate of mass transfer from potentially bioavailable (e.g., nonaqueous) phases to the directly bioavailable (e.g., aqueous) phase. Mechanisms by which sorbed (bio)surfactants influence these two processes are discussed. We propose the hypothesis that the sorption of (bio)surfactants at the solid-liquid interface is partially responsible for the increased bioavailability of surface-bound nutrients, and offer this as a basis for suggesting the development of engineered in-situ bioremediation technologies that take advantage of low (bio)surfactant concentrations. In addition, other industrial systems where bioavailability phenomena should be considered are addressed.
Biofilm modeling: present status and future directions
Authors: Noguera Daniel R. , Okabe Satoshi , Picioreanu Cristian
Published: May 2018

Biofilm models are commonly used as simulation tools in engineering applications and as research tools to identify and fill gaps in our knowledge of biofilm processes. While models used in engineering applications rely on simplifying assumptions to make them practical, recent experimental evidence of biofilm heterogeneity questions the validity of these assumptions. On the other hand, research models are becoming more complex and use advanced computational tools to mathematically investigate which factors determine the structural heterogeneity and the population dynamics of biofilms. One of the goals of advanced models is to evaluate the relevance of three-dimensional heterogeneities to the predictive capability of traditional biofilm models. In addition, biofilm models are used to evaluate experimental observations when studying a diversity of biofilm-related phenomena. Given the variety of applications of biofilm models and the different approaches that modelers have taken in recent years, a specialist group was convened to evaluate the present status and determine future directions of biofilm modeling research. The education of scientists and engineers on the fundamentals of biofilm models, the development of mathematical models for real-time control of biofilm processes, and the ability to “engineer” the biofilm structure and function (or performance) were identified as the most important objectives for the practical application of biofilm models. As mathematical research tools, biofilm models are directed towards gaining a better understanding of biofilm structure and population dynamics. Specific topics identified as priorities on biofilm research include the behavior of specialist microorganisms, the elucidation of attachment and detachment mechanisms, the determination of mechanical properties of exopolymeric substances, and the study of ecological interactions among different microorganisms. The need to evaluate parameter sensitivity in the different models was identified as an essential component of modeling research. A group decision from this meeting was to initiate a collaborative effort to identify similarities and differences among current modeling approaches. Such comparative analysis will enhance our understanding of biofilm processes and mathematical approaches, and will facilitate the future use of biofilm models by scientists and engineers involved in biofilm research.
A Simple and Low Cost Technique for Determining the Granulometry of Upflow Anaerobic Sludge Blanket Reactor Sludge
Authors: Laguna A. , Ouattara A. , Gonzalez R. O. , Baron O. , Famá G. , El Mamouni R. , Guiot S. , Monroy O. , Macarie H.
Published: May 2018

Four techniques (microscope sizing, calculation from settling velocities, image and laser analysis) are available nowadays for determining the particle size distribution of upflow anaerobic sludge blanket (UASB) reactor sludge. These techniques present however the disadvantage of being either tedious, imprecise or expensive and hardly applicable in full scale treatment plants. There was then the need for a simple and low cost technique. In this study, a granulometry procedure based on manual humid sieving was evaluated. It was shown that no solid loss occured during the screening and that the particle size profiles were reproducible when performed with sludge samples of 5, 10, 25 and 150 ml, but not 1 ml. Only the results between 10 and 25 ml were however fully identical. It was shown also that the sieving could be performed on sludge samples stored for as long as 50 days at refrigerator temperature and that tap water could be use for the wash and backwash operations without any impact on the particle size profile. The granulometry obtained by image analysis was not comparable to that given by sieving. Nevertheless, no evidence of granule erosion could be found. In any case, the technique allowed us to follow the evolution of sludge granulometry perfectly over time. As a consequence, the manual humid sieving appears to be an adequate technique for determining the granule size distribution of UASB sludges.
Coastal pollution and mitigation measures in Turkey
Authors: Samsunlu A. , Akça L.
Published: May 2018

Turkey is a developing country where industrial and urban developments mostly occur in coastal areas. Besides the present pollution loads, newly developed tourist areas and industries, through increased input of wastes, further stress the coasts of Turkey. In this study, the state of sewerage systems, treatment plants and sea outfalls in Turkish coasts were investigated. The pollution problems should be considered differently from region to region. Development of coastal areas appeared to be partially tourist and partially industrial in nature. Because of this fact, problems from different coastal areas were discussed in different projects and solutions were recommended.
Water quality of the Beli Lom river
Authors: Stamou Anastasios I. , Koumanova Bogdana , Stoyanov Stoyan , Atanasov Georgy , Pipilis Konstantinos
Published: May 2018

A general methodology for the study of water quality in rivers is presented. The paper consists of four parts. In the first part the general characteristics of the area of study, which is the Beli Lom river, and its major pollution sources are presented. The effluent of the Razgrad Wastewater Treatment Plant (RWWTP) has been identified as the most significant pollution point source, due to the inadequate performance of the plant. The second part deals with data collection and processing. Four series of data have been collected, including physical, flow and water quality characteristics. In the third part a 1-d, finite-difference, second-order model is presented. In the fourth part, the model is calibrated, for the determination of its main coefficients, and is successfully verified by predicting the BOD and DO concentrations in the Beli Lom river for all series of data. Finally, the model has been applied to determine the maximum BOD and minimum DO effluent concentrations of the RWWTP, so that a minimum DO concentration is maintained throughout the river.
Design and Startup of an Anaerobic Fluidized Bed Reactor
Authors: Marín P. , Alkalay D. , Guerrero L. , Chamy R. , Schiappacasse M. C.
Published: May 2018

A 10 1 anaerobic fluidized bed reactor (AFBR) was designed and constructed, using beach sand as the solid support for the biomass. Considering the complexity of this type of system, previously to the startup, several experiences were performed in a series of minireactors, such as: determination of the bed expansion and the feed distribution. The startup was made increasing gradually the organic load rate (OLR), using the alkalinity ratio (α) and the removal of the organic load, as mg/l of COD, as leading parameters. The system attained a COD removal of over 85%, for an OLR of 3.4 [kg COD/m3·d]. The best removal of 92% was obtained at an OLR of 1.04 [kg COD/m3·d], with a hydraulic retention time (HRT) of 12 hours. The best gas production of 1.8 [m3 of biogas/m3·d], equivalent to a production of 0.16 [m3/kg CODremoved], was obtained at an (HRT) of 4.8 hours. The best startup results were obtained using Ethanol as the Carbon source.
Denitrification in a Carbon and Nitrogen Removal System for Leachate Treatment: Performance of a Upflow Sludge Blanket (USB) Reactor
Authors: Borzacconi Liliana , Ottonello Gisela , Castelló Elena , Pelaez Heber , Gazzola Augusto , Viñas María
Published: May 2018

The performance of a bench scale upflow sludge bed (USB) denitrifying reactor was evaluated in order to integrate it into a C and N removal system for Sanitary Landfill Leachate. The raw leachate used presented COD and NH4-N average values of 30000 mg/l and 1000 mg/l, respectively. The complete system comprises in addition an UASB reactor and a nitrifying RBC. A portion of the aerobic reactor effluent was recycled into the denitrification stage and some raw leachate was also added as an additional C source. In order to obtain operating parameters the denitrifying reactor was operated alone. Sludge from an aerobic reactor (RBC) treating raw leachate was used as inoculum. Shortly after the start up, good granulation of the sludge bed was observed. Using raw leachate and UASB outlet as carbon sources with COD/NO3-N ratios of 4 and 12, respectively, denitrification efficiencies of about 90% were reached. A sludge yield of 0.16 gVSS/gCODremoved was obtained operating with raw leachate. For the anoxic reactor operating in the complete system, denitrification efficiencies of 90% were also achieved. A nitrogen gas recycle was a successful way to avoid frequently observed sludge bed rising problems.
Region-wide assessment of the land-based sources of pollution of the black sea
Authors: Sarikaya H. Z. , Sevimli M. F. , Çitil E.
Published: May 2018

Black Sea riparian countries have committed to prevent, reduce and control pollution of the marine environment of the Black Sea from land-based sources in accordance with Article VII of the Bucharest Convention. Gathering information on the sources of pollution was one of the basic requirements of the Odessa Ministerial Declaration of the Black Sea countries. This paper presents a summary of the outcome of the studies conducted to fulfil this obligation. The aim of this study has been limited to the point sources of wastewater discharges including domestic as well as industrial discharges. The inputs through main rivers were also included in the scope. Solid wastes directly or indirectly discharged or dumped into the Black Sea were not included in this study. Diffuse sources, surface runoff (storm water) and air emissions were not included in the scope of the study. In this paper, total domestic, industrial and riverine pollution loads of the major pollutants such as BOD, TSS, TN and TP were presented for each of the six Black Sea riparian countries after compilation of the data. Rapid assessment techniques of WHO were adopted in the study to estimate the pollutant loads of the point sources. The major source of contamination to the Black Sea arises as a result of the inputs of contaminants from international rivers, especially the River Danube. The other international rivers are also crucial in the pollution of the Black Sea, although the River Danube is the dominant pollutant source. The fact that the total riverine input is about 85% of the total pollution load of BOD demonstrates the significance of the control of the riverine sources. Total pollution loads of each Black Sea country and their breakdown as domestic, industrial and riverine inputs were presented both in graphical and in tabulated forms. Furthermore, the contribution of the oil pollution and pollution exchange through straits (Kerch and Bosphorus Straits) are also given.
State of the ichthyofauna in ropotamo reserve complex: ecological, conservation and economic aspects
Authors: Pehlivanov L. Z.
Published: May 2018

The aim of the investigations was to discover the actual state of the ichthyofauna in the water basins of Ropotamo Reserve Complex and to determine the ecological, conservation and economic aspects of its management. In total 55 fish species were found during this study. Five species belong to the category “threatened” in the Red Book of Bulgaria. Four species at different levels of endemism were also found. The highest species diversity characterizes the firth of Ropotamo River. In all marshes studied a comparatively low degree of species diversity was established, because of the extreme abiotic conditions, and especially because of the variable hydrological rate. The anthropogenic impact affects the studied basins to different degrees. In both Alepu and Stomopolu marshes, a more direct influence was noted. Some measures for decreasing the negative impact as well as for successful management of all water basins in the Ropotamo Reserve Complex are proposed. Realization of long-term monitoring of the water fauna, including the fish, is recommended.
HORUS: a conceptual model of pollution simulation in sewer networks
Authors: Zug M. , Bellefleur D. , Phan L. , Scrivener O.
Published: May 2018

This paper presents the conceptual model for solid production and transfer in combined or separate sewerage systems called HORUS. The objective of this model is, taking into account the characteristics of the catchment and the structure of the sewerage system, to reproduce the hydrographs, Total Suspended Solids (TSS) and Chemical Oxygen Demand (COD) concentration generated by any rainfall. HORUS consists of main connected modules and the retained algorithms have been chosen after using a special Testing Bench of Pollution Modelling Algorithm in Urban Sewer System. The main modules are: a hydrological module (linear reservoir and runoff losses), a hydraulic module (described by the Muskingum model), a module for solids production and transport (build-up and washoff of catchment and solid transport in sewer) and a module for numerical optimisation. The improvement of the HORUS model is shown by a comparison between simulation results versus the initials algorithms. Simultaneous measurements of rainfall, hydraulic, TSS and COD concentrations on nine very different catchments and about one hundred rainfall events allowed a large range of validation which can be considered of good quality. HORUS provides a satisfying fitting of the real TSS and COD pollutographs (flow and concentration) and this, considering the global form, maximal values and the temporal position.
On the Strength and Character of Alumino-Humic Flocs
Authors: Bache D. H. , Rasool E. , Moffat D. , McGilligan F. J.
Published: May 2018

The paper describes the size, density and strength of flocs gained from a humic acid suspension coagulated with aluminium sulphate over a range of dose and pH. Flocs were generated on a continuous flow basis in an oscillatory mixer. Particle size measurements were gained using CCTV and image analysis. From this, a maximum floc size (d95) was identified. A second series of experiments examined the floc sizes of the bulk precipitate alone under equivalent conditions. It was found that the overall floc sizes of the two suspensions were broadly similar, suggesting that the floc strength was dominated by a common bonding mechanism irrespective of the presence of the humic colloids. Some features of the size distribution in response to dose and pH were attributed to the influence of surface charge. Upper floc sizes were proportional to the Kolmogorov length (η) with d95/η ∼1. For typical levels of mixing, the floc strength was estimated to be on the order of 0.1 N m−2. By analysing the breakage kinetics in energy terms and relating the strength to the density of individual floc, a physically-based structural model was developed to explain the response of the floc size to the prevailing state of mixing.
An approach to simulation of dual drainage
Authors: Djordjević S. , Prodanović D. , Maksimović Č.
Published: May 2018

The paper presents the development of the field of urban drainage modelling known as dual drainage - an approach to rainfaill runoff simulation in which the numerical model takes into account not only the flow through the sewer system, but also the flow on the surface. The steps in model development are described, and necessary data, assumptions used and operations to be performed using GIS are discussed. The numerical model simultaneously handles the full dynamic equations of flow through the sewer system and simplified equations of the surface flow. The surface excess water (due to the limited capacity of inlets or to the hydraulic head in the sewer system reaching the ground level) is routed to the neighbour subcatchment (not necessarily the one attached to the downstream network node), using surface retentions, if any.
Robust numerical treatment of flow transitions at drainage pipe boundaries
Authors: Capart H. , Bogaerts C. , Kevers-Leclercq J. , Zech Y.
Published: May 2018

The present report describes a comprehensive modelling framework developed to handle flow transitions with drainage pipes and at their boundaries. The proposed numerical scheme is based on a finite volume formulation. Detailed specifications of boundary conditions at pipe ends are provided, along with a decision tree allowing to seamlessly manage transitions such as flow reversal, entrance drowning, or hydraulic jump migration through the boundaries. Proof-of-concept examples and comparison with laboratory data are given to illustrate the robustness of the proposed approach.
Simulating the influence of backwater effects in sewer systems using hydrological model components
Authors: Sartor J.
Published: May 2018

A long term simulation for a sewer network by dynamic flow routing models is very time consuming. The alternative hydrological methods (e.g. until hydrographs) have the disadvantage that they are unable to simulate backwater conditions which may significantly effect the flow hydrograph. As one possible solution this payer presents a simulation concept which includes hydrological components to model the effects of backwater or overtopping street level. However, each model component requires a calibration on dynamic routing results because the investigations showed that each sewer system reacts very individually at backwater conditions. This new concept was developed and verified at eight sewer systems.
Numerical modelling of bed load sediment traps in sewer systems by density currents
Authors: Schmitt F. , Milisic V. , Bertrand-Krajewski J.-L. , Laplace D. , Chebbo G.
Published: May 2018

A model with density currents has been developed and tested to simulate bed load sediment traps. In this model, the bed load layer over the pipe invert is considered as a continuous layer characterised by a density and a viscosity which depends on the solid concentration. A set of equations has been established that describes the trapping of the bed load material as the dynamics of two non-miscible fluids over and in the bed load sediment trap. The Fluent package has been used and adapted to solve the equations of the model. The VOF method (Volume Of Fluid) has been chosen to solve the two phase approach according to a Euler-Euler scheme. Several series of simulations have been carried out in order to assess the influence of the slot position and trap design on efficiency. The results obtained agree with previous empirical findings, and allow confirmation (in a more reliable manner than before) that the best sediment trap design involves a centrally-placed slot with the two plates covering the trap reservoir placed at the same height as one another.
Field testing CFD-based predictions of storage chamber gross solids separation efficiency
Authors: Stovin Virginia R. , Saul Adrian J. , Drinkwater Andrew , Clifforde Ian
Published: May 2018

The use of computational fluid dynamics-based techniques for predicting the gross solids and finely suspended solids separation performance of structures within urban drainage systems is becoming well established. This paper compares the result of simulated flow patterns and gross solids separation predictions with field measurements made in a full size storage chamber.

The gross solids retention efficiency was measured for six different storage chambers in the field and simulations of these chambers were undertaken using the Fluent computational fluid dynamics software. Differences between the observed and simulated flow patterns are discussed. The simulated flow fields were used to estimate chamber efficiency using particle tracking. Efficiency results are presented as efficiency cusps, with efficiency plotted as a function of settling velocity. The cusp represents a range of efficiency values, and approaches to the estimation of an overall efficiency value from these cusps are briefly discussed. Estimates of total efficiency based on the observed settling velocity distribution differed from the measured values by an average of ±17%. However, estimates of steady flow efficiency were consistently higher than the observed values. The simulated efficiencies agreed with the field observations in identifying the most efficient configuration.
Dynamic simulation of the effects of combined sewage overflow on small urban streams
Authors: Petruck A. , Jäger D. , Sperling F.
Published: May 2018

The recently developed water quality simulation model FGSM of the German Association for Water Pollution Control (ATV) has been set up to simulate major water quality parameters of a small urban stream. After collecting the necessary input data the model was calibrated for dry weather conditions. Based on the calibrated model typical combined sewage overflow events were simulated. The model was able to simulate dry weather conditions well. For the simulation of combined sewage overflow events a typical event was simulated. The model was able to simulate high peak flows almost without damping. The biological oxygen demand was shown to sharply increase up to 20 mg/l, while the oxygen concentration decreased to less than 5 mg/l. The simulation showed that dissolved oxygen levels stayed during the simulated event above 4 mg/l. The FGSM appears to be a valuable tool for assessing not only the chronic, but also the acute effects of combined sewage overflow events.
Integrating simulation and design for stormwater management
Authors: Smith Alan A.
Published: May 2018

The software discussed provides a decision support system for drainage engineers involved in the design of stormwater management facilities. Runoff modelling is versatile and involves a variety of methods for storm description, rainfall loss estimation and overland flow routing. In addition to normal pipe and channel sizing, the design options include a number of detention devices for on-site controls such as rooftop and parking lot storage, in-line storage ‘super-pipes’ and exfiltration trenches. In all cases, the program provides suggested design parameter values that the user can modify, test and accept. A special feature allows the output file from one design session to be used as input to automatically test the design for a different storm, test a change in catchment or design parameters or simply to complete a design in two or more sessions.
Micropollutants in the Danube River Basin
Authors: Literáthy P. , László F.
Published: May 2018

Monitoring programmes in river basins usually include monitoring heavy metals and selected organic micropollutants in water and sediment. Several survey results revealed contamination of the water resources in the Danube river basin. Besides those chemicals, for which regulations already exist, there are other compound classes, e.g., aromatic sulfonates, complexing agents and breakdown products that have not been considered in the past due to the lack of data on their occurrence. Such chemicals may well be relevant to water pollution, to drinking water supplies, particularly those using surface water intakes, or bankside filtered water, because of their large production volumes, persistence and polarity, although information is limited on their effects.

Harmonisation of micropollutant monitoring tools is a major goal of the international co-operation in the Danube river basin. Heavy metals, petroleum and selected chlorinated hydrocarbons are on the list of determinands. Development of analytical methods for screening and quantifying organic micropollutants resulted in: (a) information on naphthalene-sulfonates in the river water in the Hungarian Danube reach, and (b) application of fluorescence spectroscopy for screening polar and non-polar aromatic compounds. It has been concluded that the fluorescence technique and the AOX determination provide appropriate screening for both polar and non-polar aromatic compounds, and chlorinated hydrocarbons, respectively.
Use of Ambient Water Quality Data to Refine Emission Estimates in the Danube Basin
Authors: Clement A. , Buzás K.
Published: May 2018

In the frame of an EU/Phare project nutrient balances of the Danube countries were studied. As an element of the procedure, N and P emissions to surface waters were estimated on various scales. The “immission” loads computed from water quality and flow data were used to refine these estimates. The evaluation indicated the significant role of uncertainties related to scarce observations typical for many countries in the Danube Basin. To obtain the error of annual nutrient load estimates statistical analyses of a number of Hungarian rivers (in the 2 m3/s - 2000 m3/s mean flow range) were performed. Both, analytical expressions of sampling theory and Monte Carlo simulations were used. The ratio estimate and an analysis of the relation of errors of the annual mean flow and the load, resp. were used to take advantage of the additional information of flow data in comparison to water quality. An empirical error function for the range of rivers considered was derived. The effort led to useful results in relation to the selection of the estimation method, the role of sampling frequency and size of the catchment. Conclusions were also drawn on estimation errors of loads of first order tributaries of the Danube and their use in the frame of a nutrient balance study.
Nutrient Balances of the Danube Basin: The Role of Uncertainties
Authors: Buzás K.
Published: May 2018

In the framework of the Danube Environmental Program a study on the Nutrient Balances for the Danube Countries has been completed. The method of materials accounting was applied to calculate nutrient flows (including emissions into surface waters) which is based on mass balances among different components of the anthroposphere and its environment. The evaluation indicated the significant role of uncertainties and errors of various sources which are determined primarily by methodological and data related reasons. Thus, even if the entire system is numerically balanced, the procedure can lead to incorrect results (which remain hidden). To demonstrate the role of uncertainties, one component of the system, the agricultural sector was chosen. Eight major input and output nutrient flows were involved (such as agricultural nutrient discharges into surface and groundwater, and tropospheric losses). These flows (which are not independent of each other) can be estimated from linear and non linear functions of statistical data and a large number of parameters in a wide uncertainty range. To perform an error analysis, traditional (sensitivity analysis) and Monte Carlo simulations were combined. The relative contribution of the errors of parameters was analyzed. Conclusions were drawn on the applicability of the materials accounting for the estimation of agricultural N and P emissions into surface waters and cross-checking of the different propagation ways become possible.
Innovative Tools for Water Quality Management and Policy Analysis: Desert and Streamplan
Authors: De Marchi Carlo , Ivanov Pavel , Jolma Ari , Masliev Ilia , Smith Mark Griffin , Somlyódy László
Published: May 2018

This paper presents the major features of two decision support systems (DSS) for river water quality modeling and policy analysis recently developed at the International Institute of Applied Systems Analysis (IIASA), DESERT and STREAMPLAN. DESERT integrates in a single package data management, model calibration, simulation, optimization and presentation of results. DESERT has the flexibility to allow the specification of both alternative water quality models and flow hydraulics for different branches of the same river basin. Specification of these models can be done interactively through Microsoft® Windows commands and menus and an easy to use interpreted language. Detailed analysis of the effects of parameter uncertainty on water quality results is integrated into DESERT. STREAMPLAN, on the other hand, is an integrated, easy-to-use software system for analyzing alternative water quality management policies on a river basin level. These policies include uniform emission reduction and effluent standard based strategies, ambient water quality and least-cost strategies, total emission reduction under minimized costs, mixed strategies, local and regional policies, and strategies with economic instruments. A distinctive feature of STREAMPLAN is the integration of a detailed model of municipal wastewater generation with a water quality model and policy analysis tools on a river basin scale.