bluuebunny/crossref_metadata_2025 huggingface dataset:
Prediction of full-scale dewatering results of sewage sludges by the physical water distribution
Authors: Kopp J. , Dichtl N.
Published: May 2018

The dewaterabilty of sewage sludge can be described by the total solids concentration of the sludge cake and the polymer-demand for conditioning. The total solids concentration of the sludge cake depends on the physical water distribution. The various types of water in sewage sludge are mainly distinguished by the type and the intensity of their physical bonding to the solids. In a sewage sludge suspension four different types of water can be distinguished. These are the free water, which is not bound to the particles, the interstitial water, which is bound by capillary forces between the sludge flocs, the surface water, which is bound by adhesive forces and intracellular water. Only the share of free water can be separated during mechanical dewatering. It can be shown, that by thermo-gravimeteric measurement of the free water content, an exact prediction of full-scale dewatering results is possible. By separation of all free water during centrifugation the maximum dewatering result is reached. Polymer conditioning increases the velocity of the sludge water release, but the free water content is not influenced by this process. Furthermore it is not possible, to replace the measuring of the water distribution by other individual parameters such as ignition loss.
Numerical modelling of dynamic sludge blanket behaviour in secondary clarifiers
Authors: Armbruster M. , Krebs P. , Rodi W.
Published: May 2018

New developments in numerical modelling of turbulent and density-affected flow in secondary clarifiers are reported. The sludge blanket is included in the computation domain which allows us to account for sedimentation and resuspension of sludge as well as the growth and diminution of the sludge blanket and at the same time respecting mass conservation. It is shown how strongly the prediction of the sludge-blanket height depends on the approaches to describe the settling behaviour of the sludge and the rheological properties within the sludge blanket. Further, an example of dynamic simulation is presented and discussed. This demonstrates how the sludge blanket behaves during load variation and that instabilities may occur at the interface of sludge blanket and supernatant, potentially resulting in sludge wash-off during transient phases, which is not only during load increase but also during load decrease.
Human enteric viruses in Coquina clams associated with a large hepatitis A outbreak
Authors: Bosch A. , Sánchez G. , Le Guyader F. , Vanaclocha H. , Haugarreau L. , Pintó R. M.
Published: May 2018

An outbreak of hepatitis A, affecting 183 people, occurred in Valencia (Spain). Epidemiological evidence pointed to an association of the outbreak with consumption of Coquina clams (Donax sp), imported frozen from Peru. Shellfish were analysed for the presence of hepatitis A virus (HAV), enteroviruses, rotaviruses, astroviruses, caliciviruses and hepatitis E virus. HAV was detected in 75% of assayed shellfish samples. Other enteric viruses were occasionally found in the same samples. Molecular epidemiological analysis of fragments of the VP1/2A and the 5' end of the genome from shellfish and sera isolates, revealed the presence of six variants belonging to a single genotype.
Adsorption and survival of faecal coliforms, somatic coliphages and F-specific RNA phages in soil irrigated with wastewater
Authors: Gantzer C. , Gillerman L. , Kuznetsov M. , Oron G.
Published: May 2018

This study was carried out to compare the adsorption and survival of faecal coliforms, somatic coliphages and F-specific RNA phages in soil irrigated with wastewater. Adsorption isotherms showed that 3-10× more faecal coliforms than somatic coliphages were adsorbed from wastewater onto soil. The adsorption behavior of F-specific RNA phages was intermediate between those of these two microorganisms. In wastewater, the inactivation factor of somatic coliphages at 8-22°C was 5-7 lower than those of faecal coliforms. F-specific RNA phages have a decrease close to faecal coliforms. In soil, at temperatures of 8-22°C and at moistures of 15-35%, somatic coliphages survived longer than the two other microorganisms. These results seemed to be confirmed by the soil column experiments. The rate of inactivation of all microorganisms was lower in soil than in wastewater and depended extensively on soil temperature and moisture content. Survival was optimal at low temperature (8°C) and low moisture content (15%). Thus, somatic coliphages seemed to be a better indicator of faecal contamination than faecal coliforms under our experimental conditions and based only on the two criteria tested (survival and adsorption). Somatic coliphages were able to contaminate the soil over greater distances and survive better in both wastewater and soil than faecal coliforms. These results need to be confirmed by studies on several soil columns using different kinds of soil and different kinds of wastewater.
Seine Centre, the new flexible Colombes sewage treatment plant - from theory to practice
Authors: Paffoni C.
Published: May 2018

Upon the filling of the Seine Centre sewage plant in May 1998, the SIAAP commissioned its first wastewater treatment plant adapted for handling part of the large amounts of rain period surplus water: its flow rate ranges from 2.8 m3/s during dry weather to 12 m3/s in wet weather conditions. Four operational configurations for treating 240,000 m3/day during dry weather, with different quality objectives, and three configurations for treating the rain period surplus water were designed. Immediately upon filling of the plant, however, the operators had to devise innovative configurations for meeting new discharge standards. This paper will aim at demonstrating (considering a major achievement the various aspects of which will be explained) the SIAAP's will to conform in real time, through a dynamic management of its facilities, to the variation of the priorities in the environmental demands, while preserving the quality of the adjacent owners' immediate environment.
International product cost comparison in the field of water management
Authors: Bode H. , Lemmel P.
Published: May 2018

Comparing international costs in the field of water management is difficult. The frame conditions in the various countries are very different. They influence the costs and particularly the sewage charges in a complex way. Some of these conditions are outlined by analyzing the situation in Germany as a “case study”. An objective comparison should deal with the in situ arising product costs as annual costs. The product costs consist of both the operating and the capital costs. The annual product costs of 34 wastewater treatment plants in six different European countries are presented. The observed differences in the quality of the construction and of the mechanical equipment of the plants were taken into account with different depreciation periods. The product costs in four of six countries, including Germany, were found to be nearly at the same level. Although the German frame conditions are demanding and difficult the expectation of outstanding high product costs was not confirmed.
Application of performance indicators in water utilities management - a case-study in Portugal
Authors: Marques R. C. , Monteiro A. J.
Published: May 2018

This paper presents some issues concerning water supply systems assessment through performance indicators, based upon research work recently carried out in Portugal about water utilities. A proposal of 50 performance indicators divided into five different groups is presented here, namely structural indicators, operational indicators, water and service quality indicators, personnel indicators and economic indicators. These indicators were associated with a hierarchical structure of knowledge or development according to different levels: basic level, development level and strategic level. The performance indicators, structure, their implementation and assessment methodology and examples of some indicators, use concerning the characterisation or assessment of a water utility are also presented in the paper.
Validation and implementation of model based control strategies at an industrial wastewater treatment plant
Authors: Demey D. , Vanderhaegen B. , Vanhooren H. , Liessens J. , Van Eyck L. , Hopkins L. , Vanrolleghem P. A.
Published: May 2018

In this paper, the practical implementation and validation of advanced control strategies, designed using model based techniques, at an industrial wastewater treatment plant is demonstrated. The plant under study is treating the wastewater of a large pharmaceutical production facility. The process characteristics of the wastewater treatment were quantified by means of tracer tests, intensive measurement campaigns and the use of on-line sensors. In parallel, a dynamical model of the complete wastewater plant was developed according to the specific kinetic characteristics of the sludge and the highly varying composition of the industrial wastewater. Based on real-time data and dynamic models, control strategies for the equalisation system, the polymer dosing and phosphorus addition were established. The control strategies are being integrated in the existing SCADA system combining traditional PLC technology with robust PC based control calculations. The use of intelligent control in wastewater treatment offers a wide spectrum of possibilities to upgrade existing plants, to increase the capacity of the plant and to eliminate peaks. This can result in a more stable and secure overall performance and, finally, in cost savings. The use of on-line sensors has a potential not only for monitoring concentrations, but also for manipulating flows and concentrations. This way the performance of the plant can be secured.
Designing a new flushing machine: a compromise between tradition and modernity
Authors: Cardinaud J. , Martaud M.
Published: May 2018

Sewer cleaning has always been difficult and unhealthy work. Paris had to contrive, for sewermen, specific flushing units for removing grit from its interceptors. These machines, which are over a hundred years old and only take power from the water flow, could not be replaced by more mechanised systems based upon different concepts. It appears from these setbacks that all the connections with the past should not be severed; on the contrary, one should initiate a process relying upon a thorough review of the existing equipment and a new approach to in-water grit flushing. The resulting data then served as a basis for devising the concept of a new flushing machine which, though not revolutionary, will meet the operators' expectations.
Urban catchment management in a developing country: the Lotus River project, Cape Town, South Africa
Authors: Grobicki A. M.W.
Published: May 2018

This paper describes a 2-year pilot project undertaken in an urban catchment in Cape Town, South Africa. The impermeable area of the Lotus River catchment has doubled over 15 years, from 17% in 1983 to 34% in 1997. Following the abolition of urban influx control in 1990, informal settlements in the catchment grew rapidly and now house about 90,000 out of the catchment's total population of 380,000 people. The informal areas are still largely unserviced, despite a commitment from local government to speed up service delivery to the poorest areas of the city.

Within the Lotus River project, hydrological and ecological assessments of the urban watercourses were undertaken, through physico-chemical and microbiological sampling programmes, macro-invertebrate counts, and vegetation sampling. All available information regarding the catchment was integrated within a GIS platform, including demographic and socio-economic data on the various communities, and hydrogeological information on the underlying aquifer obtained from earlier studies. The integrated nature of the project allows a number of conclusions and recommendations to be drawn, regarding the management of this particular catchment. However, important general lessons have also been learned which can be applied by local authorities responsible for urban catchments in developing countries. The necessity of providing the required institutional structures cannot be overemphasised.
Kaolinite sorption of Cd, Ni and Cu from landfill leachates: influence of leachate composition
Authors: Petrangeli Papini M. , Majone M. , Rolle E.
Published: May 2018

Heavy metal speciation in landfill leachates plays a significant role in determining the mobility during the percolation through soils. The complexation characteristics of landfill leachate directly affects heavy metal solubility and the extent of the interaction with soils, lowering or arising the sorbed amount depending on the relative affinity of the complexed metal and uncomplexed form to soil adsorption sites. In this paper, the adsorption of Cd, Ni and Cu onto kaolinite from three leachates (collected from landfill at different fermentation stage) is studied, also in comparison with metal speciation by two different operative procedures. The heavy metals, at their natural concentration, were divided into operational classes according to an exchange-based procedure and by fractionation on the basis of molecular weight (exchange onto Chelex100 resin and ultrafiltration, respectively). All the experiments were performed also on synthetic solutions designed according to leachate composition and theoretical speciation. The experimental results have shown leachate complexing capacity is strongly dependent on landfill age, and that broad parameters such as COD, DOC, pH, ionic strength and VFA concentration are not able to predict it. It is notheworthy that the strong complexing capacity of leachate can cause extraction of metals from the solid phase instead of adsorption from the liquid one.
Combined ozone-activated sludge treatment of landfill leachate
Authors: Geenens D. , Bixio B. , Thoeye C.
Published: May 2018

Biological treatment is widely preferred by many landfill owners to remove the bulk of the pollutants in leachate. Specific problems due to toxicity and nutrient deficiencies are however frequently reported. This study investigates the possibility of pre-treating leachate to decrease its toxicity and increase its biodegradability, using ozonation. Lab-scale and pilot testing has shown that nitrification toxicity was minimised by ozone pre-treatment. A decrease of the COD/BOD-ratio from 16 to 6 was achieved, making the pre-treated leachate co-treatable in municipal sewage treatment. The operational cost for the pre-treatment was estimated at 1.34 Euro/kg COD.
The influence of biosolids treatment files on the mobility of metal trace elements
Authors: Maisonnave V. , Montrejaud-Vignoles M. , Bonnin C. , Revel J.-C. , Vignoles C.
Published: May 2018

The production of sludge in France is estimated to be about 900,000 metric tons dry matter per year and 60% of this is recycled onto agricultural land. At present, the long term future of this procedure is open to question and among the different arguments being put forward are the levels of metallic trace elements and the risk of accumulation in soils.

This study presents the behaviour of metallic trace elements in sludges from three different treatment procedures: thickened liquid sludges, dewatered sludges and dried sludges. These biosolids are mixed with a clay soil and then placed in a temperature and humidity controlled glasshouse. Several containers are seeded with ryegrass and compared with controls. For the three harvests, covering all the amendments studied (including non-amended soil), the differences are not really representative. Absorption by the ryegrass is low in all cases. For the cadmium, the chromium, the nickel and the lead, the roots are 5 to 10 times more concentrated than the leaves. The majority of these elements stay absorbed in the roots, regardless of the amendment used.

The addition of the sludges has considerably reduced the uptake of water in ryegrass throughout its growth cycle. Quite apart from their fertilizing qualities, wastewater treatment plant sludges could offer important implications for irrigation.
Fundamental processes within natural and constructed wetland ecosystems: short-term versus long-term objectives
Authors: Wetzel R.G.
Published: May 2018

Use of wetland ecosystems for water pollution control consists essentially of sustained induced disturbances as pollutants are loaded to complex biological communities. Objectives are to maximize pollutant loading, incorporation, and retention while maintaining highest levels of community metabolism and minimal alteration of community structure. Several basic processes are emphasized: (a) macrophyte productivity in relation to shoot:root ratios, and nutrient availability; (b) macrophyte life history strategies, succession, and biodiversity under constant pollutant stress; (c) importance of standing dead and particulate detritus; (d) functions and controlling mechanisms of heterotrophic and autotrophic periphyton in pollutant retention and recycling; (e) coupling of microbial metabolism to macrophyte retention of pollutants; (f) gaseous losses to the atmosphere; (g) losses of dissolved organic matter and its utilization; and (h) water losses by evapotranspiration and effects on wetland efficacy. Short-term wetland removal efficiencies are confounded by massive variations in retentive capacities diurnally, seasonally, and spatially, in exceeding physiological tolerance levels, and in species succession. Problems of channelization, altered microhydrology, and assimilation/retention are major in natural and non-engineered ecosystems. Wetlands are highly ephemeral and variable in their capabilities for sequestering and retention of nutrients and other pollutants.
Plants as ecosystem engineers in subsurface-flow treatment wetlands
Authors: Tanner C.C.
Published: May 2018

Mass balance performance data from side by side studies of planted and unplanted gravel-bed treatment wetlands with horizontal subsurface-flow are compared. Planted systems showed enhanced nitrogen and initial phosphorus removal, but only small improvements in disinfection, BOD, COD and suspended solids removal. Direct nutrient uptake by plants was insufficient to account for more than a fraction of the improved removal shown by planted systems. Roles of plants as ecosystem engineers are summarised, with organic matter production and root-zone oxygen release identified as key factors influencing nutrient transformation and sequestration.
The removal of nutrients from plant nursery irrigation runoff in subsurface horizontal-flow wetlands
Authors: Headley T.R. , Huett D.O. , Davison L.
Published: May 2018

In New South Wales (NSW) Australia, the recent introduction of legislation to control runoff and charge for water used in agricultural production has encouraged commercial plant nurseries to collect and recycle their irrigation drainage. Runoff from a nursery typically contains around 6 mg/L TN (> 70% as NO3), 0.5 mg/L TP (> 50% as PO4), and virtually no organic matter (BOD <5 mg/L; DOC <20 mg/L). As a result, algal blooms frequently occur in storage dams. This paper describes a study evaluating the effectiveness of subsurface flow wetlands in the removal of nutrients from nursery runoff on the sub-tropical northern coast of NSW, Australia. Four experimental subsurface flow wetlands (1 m×4 m×0.5 m water depth) were planted with Phragmites australis in April 1999. TN and TP load removals were > 84% and > 65% respectively at HRTs of between 5 and 2 days, with the majority of out-flowing TN and TP being organic in form. Internal generation of organic N and P resulted in persistent background levels of 0.45 mg/L TN and 0.15 mg/L TP in the reed bed effluent. TN, NH4 and TP removal was affected by HRT (P <0.05). Greater than 90% load removal of NH4, NO2, NO3 and Ortho-P was achieved at all HRTs, with outlet concentrations generally <0.01 mg/L for all. For TN, a strong relationship existed between removal rate (g/m2/day) and loading rate (r2=0.995), while a weaker relationship existed for TP (r2=0.47). It is estimated that a 1 ha nursery would require a reed bed area of 200 m2 for a 2 day HRT.
Accumulation of organic matter fractions in a gravel-bed constructed wetland
Authors: Nguyen L.
Published: May 2018

The function of a gravel-bed wetland in treating wastewaters is dependent on the turn-over rate of organic matter (OM) fractions in accumulated solids. Organic deposits from a gravel-bed planted (Schoenoplectus tabernaemontani) wetland, which had experienced pore clogging after 5 years of receiving farm dairy wastewater were therefore collected and determined for labile (water-soluble) and stable (humic acid, fulvic acid and humin) OM fractions, total carbon (C), microbial biomass and microbial respiration rate. Over 90% of the accumulated organic solids was present as stable fractions, with humic compounds at least 2-fold higher in surface deposits and the top 100mm of the gravel bed than the lower gravel substratum. Clogging of the gravel pore spaces over a 5-year wetland operation was probably due to the accumulation of refractory (stable) organic solids, particularly in the top 100 mm of the gravel bed. Microbial respiration rate and microbial biomass were significantly correlated with stable OM fractions, suggesting that these microbial parameters may be used to predict the nature of accumulated OM fractions. Further research is required to evaluate the use of these parameters as indicators of labile and stable fractions in wetlands with a range of OM loadings and accumulation.
Evaluation of atrazine removal processes in a wetland
Authors: Kao C.M. , Wang J.Y. , Wu M.J.
Published: May 2018

Agricultural non-point source (NPS) pollution is considered to be the largest single category resulting in water quality deterioration. Pesticide is one of the main detrimental agricultural NPS constituents causing the impairment of water bodies. In this study, a mountainous wetland located in McDowell County, North Carolina, was selected to demonstrate the effects of the natural wetland system on the removal of NPS pesticide (atrazine) pollution to maintain the surface water quality. The selected wetland receives water from two unnamed creeks, which drain primarily agricultural lands. The hydraulic retention time (HRT) for the wetland was approximately 10.5 days based on the results from a dye release study. Water quality monitoring of the wetland was conducted from March to October 1998. One major storm and baseline water quality samples were analyzed. Analytical results indicate that the wetland completely removed NPS atrazine flushed from the upgradient agricultural lands. Laboratory microcosm experiments were conducted to evaluate the feasibility of using the wetland sediments as the microbial sources to enhance the atrazine biodegradation. Microcosm results suggest that atrazine can be degraded under anaerobic or reductive dechlorinating conditions when sucrose was provided as the primary substrate. Atrazine can also serve as the nitrogen source for the growth of microorganisms under anaerobic conditions. Results from this study can provide us with further knowledge on evaluating the role of wetlands in controlling pesticide pollutants from stormwater runoff.
An experimental constructed wetland system for the treatment of highway runoff in the UK
Authors: Shutes R.B.E. , Revitt D.M. , Scholes L.N.L. , Forshaw M. , Winter B.
Published: May 2018

This paper compares the performance of an experimental highway runoff treatment system, incorporating a subsurface flow constructed wetland, with that of a vegetated balancing pond. Both systems are located on the same major road in the UK which opened in November 1998. Copper, chromium and nickel total aqueous metal concentrations, although low, have been consistently removed (maximum efficiencies of 67.3, 69.8 and 87.0% respectively in the constructed wetland), particularly in the summer. Zinc showed the highest aqueous metal concentrations and the generally positive removal by the constructed wetland system (maximum efficiency of 60.6%) correlates with the expected metal uptake by Typha latifolia and Phragmites australis. Sediment levels for these metals and for lead progressively decreased over the one year monitoring period. For the two storm events monitored in the constructed wetland system, all metals showed evidence of removal (removal efficiencies of 24.2 to 99.4%) except for copper. Lead and cadmium demonstrated the highest removal efficiencies followed by nickel and zinc. For both storms, the wetland acted as a source of copper (removal efficiencies of -88.4 to -97.1%), which may be explained by the die-back of aquatic plants and consequent release of organically bound copper.
Low cost reclamation using the Advanced Integrated Wastewater Pond Systems® Technology and reverse osmosis
Authors: Downing J.B. , Bracco E. , Green F.B. , Ku A.Y. , Lundquist T.J. , Zubieta I.X. , Oswald W.J.
Published: May 2018

The sustainability of wastewater reclamation and reuse schemes is often limited by the increase in salt concentration that occurs with each water use. In this pilot study, we show that the cost of reclaiming wastewater and removing salt can be dramatically decreased by integrating recent advances in wastewater pond design, solids separation equipment, and membrane technology. Effluent from an AIWPS® Facility was clarified in a Krofta® SupracellTM Dissolved Air Flotation (DAF) unit and a Slow Sand Filter (SSF) prior to final treatment in an Expertise S.r.l. reverse osmosis (RO) unit. The ponds of the AIWPS® Facility removed an average of 82% of soluble BOD and 80% of soluble nitrogen. Following clarification, filtration, and RO treatment, the pollutant removals were > 99% for soluble BOD, > 99% for soluble nitrogen, and 98% for TDS. Based on membrane fouling rate data, the cleaning interval for the RO membranes in a full-scale AIWPS®-RO Facility would be over 100 days. This interval is on par with that typically seen in full-scale reclamation facilities treating secondary activated sludge effluent with microfiltration prior to reverse osmosis. A 4-MLD AIWPS®-RO Facility is expected to produce permeate water at substantially lower cost and lower energy consumption (US $698 and 443 kWh per million liters treated) than a system of equal capacity using conventional activated sludge secondary treatment followed by microfiltration and reverse osmosis (US $1274 and 911 kWh per million litres treated). This cost and energy differential is attributable to the lower capital and operating expenses of the AIWPS® Technology in comparison with activated sludge.
Regional frequency analysis of extreme rainfalls
Authors: Nguyen V-T-V. , Nguyen T.-D. , Ashkar F.
Published: May 2018

This study proposes two alternative methods for estimating the distribution of extreme rainfalls for sites where rainfall data are available (gaged sites) and for locations without data (ungaged sites). The first method deals with the estimation of short-duration rainfall extremes from available rainfall data for longer durations using the “scale-invariance” concept to account for the relationship between statistical properties of extreme rainfall processes for different time scales. The second method is concerned with the estimation of extreme rainfalls for ungaged sites. This method relies on a new definition of homogeneous sites. Results of the numerical application using data from a network of 10 recording rain gauges in Quebec (Canada) indicate that the proposed methods are able to provide extreme rainfall estimates that are comparable with those based on observed at-site rainfall data.
Increasing wastewater system performance – the importance of interactions between sewerage and wastewater treatment
Authors: Langeveld J.G. , Clemens F.H.L.R. , van der Graaf J.H.J.M.
Published: May 2018

The necessity to assess sewer systems and wastewater treatment plants (WWTPs) as integral parts of the wastewater system has been well known for several years and discussed in many conferences. Until recently, sewer systems and WWTPs were improved (or optimised) separately or independently, which resulted in suboptimal solutions. Nowadays, in the Netherlands as well as in other European countries, a trend can be recognised towards more integral solutions. Nevertheless, due to a lack of knowledge on the interactions between the sewer systems and the WWTPs the implementation of this way of thinking in practice takes a long time. This paper describes the results of two cases in which the interactions between sewerage and wastewater treatment are incorporated within the optimisation of a wastewater system. The first case illustrates the importance of taking the interactions into account, while the second case shows how to deal with the interactions within a wastewater system optimisation study. It is concluded that the combination of total wastewater system analysis, incorporating the interactions within the wastewater system, with efficient search algorithms is expected to be very valuable in future wastewater system optimisation studies.
Anaerobic transformations of wastewater organic matter and sulfide production – investigations in a pilot plant pressure sewer
Authors: Tanaka N. , Hvitved-Jacobsen T.
Published: May 2018

Anaerobic transformations of wastewater organic matter and sulfide production rate were studied using a pilot plant pressure sewer (inner diameter: 102 mm, length: 47 m). Furthermore, a process model description including carbon and sulfur cycle was presented. Wastewater characterization based on oxygen utilization rate (OUR) measurement and VFA analysis was employed. Under anaerobic conditions, a net production of readily biodegradable substrate was observed, which fact is important for biological removal of nitrogen and phosphorus at subsequent wastewater treatment plants. Model parameters were determined on the basis of experimental findings. The model simulation of transformations of organic matter in sewers can be used as input to the model simulation and evaluation of the processes in wastewater treatment plants. The model is also useful to evaluate the problems in both sewers themselves and treatment plants caused by hydrogen sulfide.
Deterministic modelling of integrated urban drainage systems
Authors: Rauch W. , Bertrand-Krajewski J.-L. , Krebs P. , Mark O. , Schilling W. , Schütze M. , Vanrolleghem P.A.
Published: May 2018

Today, the main concepts required for describing the dynamics of drainage in an entire urban area are known and models are available that can reasonably simulate the behaviour of the urban water system. Still, such integrated modelling is a complex exercise not only due to the sheer size of the model, but also due to the different modelling approaches that reflect the history of the sub-models used and of the purpose they were built for. The paper reviews the state of the art in deterministic modelling, outlines experiences and discusses problems and future developments.
Implementation of a monitoring system to measure impact of stormwater runoff infiltration
Authors: Barraud S. , Gibert J. , Winiarski T. , Bertrand Krajewski J.-L.
Published: May 2018

Stormwater infiltration is a drainage mode, which is more and more used in urban areas in France. Given the characteristics of urban surfaces, and especially the loads of various pollutants contained in stormwater, it is important to assess the impact of stormwater infiltration systems on soil and groundwater by carrying out field experiments. The main difficulty is due to the complexity of the system observed and the need of multidisciplinary approaches. Another difficulty is that measurements are carried out in situ, in an uncontrolled environment submitted to quantitatively and qualitatively highly variable interferences. Very long term monitoring is needed to get representative results. In order to contribute to solve these problems, the OTHU project has recently been launched in Lyon (France). One of its key action concerns a long-term (10 years) experiment on an infiltration basin specifically rehabilitated for measurements and operational drainage issues. This paper presents the experimental site, the objectives of the project and the way the monitoring process has been built according to the various disciplines involved (biology, ecology, hydrology, chemistry and soil sciences) and to the will of assessing all the uncertainties in the measurement process.
Pollution based real time control of wastewater systems
Authors: Risholt L.P. , Schilling W. , Erbe V. , Alex J.
Published: May 2018

Wastewater systems are traditionally built as static systems to handle a design load. The real load varies, though, and hardly ever equals the design load. This implies that wastewater systems hardly ever operate in an optimum way, especially during wet weather. Real time control (RTC) of regulators can improve the operation by better fit of the system to the actual state and load. RTC based on pollutant concentrations together with hydraulic conditions (pollution based real time control, PBRTC) is investigated in this paper to assess the potential pollutant load reduction on receiving waters at wet weather without expansion of transport or storage capacity. Both CSOs and WWTP effluents contribute to the pollutant discharges to receiving waters and both are considered. Three cases are studied to assess the potential benefit of PBRTC. Giving priority to the most polluted wastewater for treatment and storage in branched interceptor systems can reduce CSO discharge loads by more than 20%. Biological WWTPs and especially activated sludge plants are more complex and less stable than chemical precipitation plants during and after high pollutant and hydraulic load. Biological plants can hence profit more from PBRTC than chemical precipitation plants. Receiving waters that are sensitive to acute effects caused by intermittent discharges can benefit more from PBRTC than receiving waters with problems connected to long-term accumulation of pollution.
Modelling of activated sludge processes with structured biomass
Authors: van Loosdrecht M.C.M. , Heijnen J.J.
Published: May 2018

Bacterial communities when subjected to feast-famine conditions as occurring in many wastewater treatment systems store substrates as reserve polymers. Including storage polymers in a description of microbial growth processes makes important the choice of kinetic relations. Presently there is no sound description for the diversion of substrate towards biomass growth or substrate storage. Based on observations with pure cultures and mixed cultures growing under dynamic conditions a model is proposed to describe such behaviour. This description is based on the observation that bacteria in order to grow fast have to induce a high level of RNA and proteins in order to allow fast growth. We assume that this protein synthesising system is only induced in the presence of external substrates. Based on this assumption a model structure is proposed and evaluated. It seems that this model can predict the turnover of PHA in the cells correctly, and describes well the overall behaviour mixed culture SBR systems. However especially the growth rate in the famine phase seems to be overestimated. The model defined here is a contribution to a further development of mechanistically based models for activated sludge processes.
The EAWAG Bio-P module for activated sludge model No. 3
Authors: Siegrist H. , Rieger L. , Koch G. , Kühnl M. , Gujer W.
Published: May 2018

An additional module for the prediction of enhanced biological phosphorus removal is presented on the basis of a calibrated version of ASM3. The module uses modified processes from ASM2d but neglects the fermentation of readily degradable substrate. Biomass decay is modeled in the form of endogenous respiration as in ASM3. The glycogen pool and biologically induced P-precipitation is not taken into account. The module was systematically calibrated with experimental data from various batch experiments, a full-scale WWTP and a pilot plant treating Swiss municipal wastewater. A standard parameter set allowed all data to be simulated.
Design rules and impact assessment for source control measures based on continuous long-term simulations
Authors: Vaes G. , Berlamont J.
Published: May 2018

In recent years, more emphasis has been put on source control measures in order to reduce the peak runoff from urban areas during wet weather conditions. This involves the construction of upstream storage and infiltration facilities and rainwater tanks for reuse in households and the revaluation of ditches. Because of the long emptying times of source control facilities, a long antecedent period of rainfall influences the design. In addition, these facilities most often have an outflow which is not linearly varying with the storage. Because of the high variability of the rainfall, the required storage volumes can therefore only be assessed well if continuous simulations with long rainfall series are performed. Based on long-term simulations design rules have been set-up for source control measures in Flanders.
Sediment transport in grassed swales during simulated runoff events
Authors: Bäckström M.
Published: May 2018

Particle trapping in nine different grassed swales was measured successfully with a standardised runoff event simulation procedure. The percentage of total suspended solids removed ranged from 79 to 98%. It was found that sedimentation processes, rather than grass filtration governed the overall particle trapping efficiency. The highest particle trapping efficiency was observed in the field swales with dense, fully developed turf. A high infiltration rate was beneficial for the particle trapping and an increased swale length made it possible for smaller particles to be captured. A densely vegetated, ten metre long swale, receiving a stormwater flow of 1.0 litres per second, may capture a majority of the waterborne particles with settling velocities larger than 0.1 metres per hour. A simple model of particle trapping efficiency in grassed swales was developed and tested. It was found that mean swale residence time could be used as a design parameter for particle removal in grassed swales. The suggested exponential relationship between mean swale residence time and particle settling velocity associated with a certain trapping efficiency is so far only valid for a limited range of swale designs and residence times.
Oil bio-degradation in permeable pavements by microbial communities
Authors: Newman A.P. , Pratt C.J. , Coupe S.J. , Cresswell N.
Published: May 2018

This paper reports on continuing research at Coventry University into the improvement of highway water quality following flow through a permeable pavement. Such pavements have been shown elsewhere to be efficient in-situ bio-reactors, capable of degrading large quantities of clean motor oil. Further laboratory research, reported here, demonstrates that a commercially obtained oil degrading, microbial mixture was not significantly better at degrading clean motor oil than the indigenous microbial biomass established within the pavement over a 4-year period, when provided with an adequate nutrient supply. Scanning electron microscopy has been used to monitor biofilm development, which has also identified that the pavement has developed a complex community structure with high bio-diversity.
Environmetric approaches to estimate pollution impacts on a coastal area by sediment and river water studies
Authors: Mihailov G. , Simeonov V. , Nikolov N. , Mirinchev G.
Published: May 2018

This paper represents an effort to demonstrate the opportunities of some environmetric methods like regression analysis, cluster analysis and principal components analysis. Their role for data modeling is stressed and the basic theoretical principles are given. The application of the multivariate statistical methods is illustrated by two major examples: Assessment of metal pollution based on multivariate statistical modeling of “hot spot” sediments from the Black Sea; and a trend study of Kamchia River water quality. In the first part of the study the environmetric approach makes it possible to separate three zones of the marine environment with different levels of pollution (Bourgas gulf, Varna gulf and lake buffer zone). Further, the extraction of four latent factors offers a specific interpretation of the possible pollution sources and separates the natural factors from the anthropogenic ones, the latter originating from contamination by chemical and steel-works and an oil refinery. In the second part of the study nine sampling sites along Kamchia River were considered as sources for water quality monitoring data. Trends for all parameters are calculated by the use of linear regression analysis and special attention is paid to a specific coastal site. Then five latent factors were extracted from the monitoring data set in order to gain information about some structural characteristics of the set.
Wastewater management in coastal urban areas: the case of Greece
Authors: Paraskevas P.A. , Giokas D.L. , Lekkas T.D.
Published: May 2018

The continuously increasing quantities of municipal and industrial wastewater discharged into the sea environment degrade the quality of the water. In this paper, the recent technologies are evaluated, and the practices recommended for the wastewater treatment in coastal urban areas are analyzed, with respect to the requirements of the EU legislation. Also the principles for the disposal of the treated wastewater are discussed. Finally, a brief review of the current situation of wastewater management in Greece is given, regarding the treatment strategies previously presented.
Integrating river basin management and the coastal zone: the (blue) Danube and the (black) Sea
Authors: Maksimović Č , Makropoulos C.K.
Published: May 2018

In order to effectively manage the wide variety of physical, chemical biological and ecological processes in a sensitive coastal environment such as the Black Sea, current environmental management objectives are no longer sufficient: a new management approach has to address the intimate functional linkage between the river basin and the costal environment. Current water quality legislation requires compliance to emission levels based on the chemical analysis of water samples taken at discharge points, such as treatment plants discharging into rivers. While such measures provide a relative indication of the water quality at the point of discharge, they fail to describe accurately and sufficiently the quality of the water received from the watershed or basin. As water flows through the catchment, rainfall run-off from urban and agricultural areas carries sediments, pesticides, and other chemicals into river systems, which lead to coastal waters. The impact of the Kosovo crisis on the Danube ecosystems provides a poignant example of the effects of such diffused pollution mechanisms and reveals a number of interesting pollution mechanisms. This paper discusses both the effects of diffused pollution on the Black Sea, drawing from state-of-the-art reports on the Danube, and proposes a framework for a decision support system based on distributed hydrological and pollution transport simulation models and GIS. The use of ecological health indicators and fuzzy inference supporting decisions on regional planning within this framework is also advocated. It is also argued that even the recently produced GEF document on Black Sea protection scenarios should benefit significantly if the concept of pollution reduction from both urban, industrial and rural areas should undergo a systematic conceptual update in the view of the recent recommendations of the UNEP IETC (2000) document.
SeaWiFs satellite data analysis of Black Sea water discharge pattern into the Aegean Sea
Authors: Jönsson L.
Published: May 2018

Satellite data from the SeaWiFS sensor has been used to determine chlorophyll-a contents in the North Aegean Sea using SEADAS 3.3 software. The data is used to extract knowledge on water movements/flow phenomena using chlorophyll as a “tracer” but will also indicate water quality. More than 100 SeaWiFS scenes from 1998 up to 2001 have been analyzed in terms of hydrodynamic phenomena, mainly the transport and spreading pattern of Black Sea Water in the North Aegean Sea but also concerning the water quality and its seasonal and yearly variation at the mouth region of the Dardanelles. Some comparison with earlier studies using NOAA AVHRR thermal data and historical CZCS scenes is also made.
Hydrogeological constraints on riparian buffers for reduction of diffuse pollution: examples from the Bear Creek watershed in Iowa, USA
Authors: Simpkins W.W. , Wineland T.R. , Andress R.J. , Johnston D.A. , Caron G.C. , Isenhart T.M. , Schultz R.C.
Published: May 2018

Riparian Management Systems (RiMS) have been proposed to minimize the impacts of agricultural production and improve water quality in Iowa in the Midwestern USA. As part of RiMS, multi-species riparian buffers have been shown to decrease nutrient, pesticide, and sediment concentrations in runoff from adjacent crop fields. However, their effect on nutrients and pesticides moving in groundwater beneath buffers has been discussed only in limited and idealized hydrogeologic settings. Studies in the Bear Creek watershed of central Iowa show the variability inherent in hydrogeologic systems at the watershed scale, some of which may be favorable or unfavorable to future implementation of buffers. Buffers may be optimized by choosing hydrogeologic systems where a shallow groundwater flow system channels water directly through the riparian buffer at velocities that allow for processes such as denitrification to occur.
Effect of a cold-climate buffer zone on minimising diffuse pollution from agriculture
Authors: Syversen N.
Published: May 2018

Vegetative buffer zones adjacent to streams can filter diffuse pollution from agriculture. Under Nordic climatic conditions, major runoff from agriculture occurs during winter and especially during snowmelt. Field experiments documenting runoff and retention processes in buffer zones during winter conditions are essential. Agricultural runoff and buffer zone retention of nutrients and particles during winter and summer are compared. The study is based upon 8 years of data collected from 5 to 10 m wide buffer zones compared to plots without buffer zones. Volume proportional samples were collected after each runoff episode. Results show that the difference between precipitation and runoff is much higher during summer than winter, due to higher evapotranspiration and infiltration during the summer. Over 90% of total particle and phosphorus runoff occurred during winter. There was no significant difference in retention of particles and particle-bound nutrients during winter compared to summer. Sedimentation is one of the most important retention processes in surface runoff buffer zones. High retention during winter is probably caused by higher surface runoff and erosion. High surface runoff and flow velocity could cause erosion of coarser particles, which were more easily trapped in the buffer zone. High particle concentration in the runoff water may also enhance the aggregation of fine particles.