bluuebunny/crossref_metadata_2025 huggingface dataset:
Solids separation efficiency of combined sewer overflows
Authors: Luyckx G. , Vaes G. , Berlamont J.
Published: May 2018

The removal of sewer solids at combined sewer overflow locations depends on the flow patterns inside the overflow structure on the one hand and on the sediment characteristics on the other hand. Flow conditions can be described by the residence time distribution; sewer sediments can be characterised by their settling velocity distribution. The combination of both distributions leads to a dimensionless efficiency curve, which gives the removal efficiency as a function of the Hazen number. For field conditions this efficiency curve is mainly influenced by the settling velocity distribution of the sewer sediments and, as a consequence, nearly identical efficiency curves are found for different types of prototype CSO structure. For design purposes, a methodology using return frequency analysis is proposed.
Performance indicators for the efficiency analysis of urban drainage systems
Authors: Artina S. , Becciu G. , Maglionico M. , Paoletti A. , Sanfilippo U.
Published: May 2018

Performance indicators implemented in a decision support system (DSS) for the technical, managerial and economic evaluation of urban drainage systems (UDS), called MOMA FD, are presented. Several kinds of information are collected and processed by MOMA FD to evaluate both present situation and future scenarios of development and enhancement. Particular interest is focused on the evaluation of the environmental impact, which is considered a very relevant factor in the decision making process to identify the priorities for UDS improvements.
Inefficiency of storm water inlets as a source of urban floods
Authors: Despotovic J. , Plavsic J. , Stefanovic N. , Pavlovic D.
Published: May 2018

The paper attempts to explain sources of surplus storm water runoff in urban areas, particularly in relation with functioning of inlets. Inlet capacity (quantity of captured water) and inlet efficiency (portion of the approaching flow rate) have been defined and their relationship with relevant parameters (approaching flow, longitudinal and lateral street slopes) was established through laboratory measurements. Effects of clogging of inlets on inlet capacity were also investigated in laboratory conditions. As a consequence of decreased inlet efficiency, there is a portion of approaching flow that is not captured by the inlet (pass-over flow). If the pass-over flow is considered along a street having numerous inlets, it is easy to estimate the quantity of flow that would accumulate on the pavement. Inlet inefficiency can be significant when overestimation of inlet capacity results in increased distance between consecutive inlets, and when clogging of grates or inadequate placing of inlets causes significant decrease in inlet capacity.
Factors influencing exfiltration processes in sewers
Authors: Blackwood D.J. , Ellis J.B. , Revitt D.M. , Gilmour D.J.
Published: May 2018

Exfiltration from sewers is widespread and emerging legislation may require water service providers to identify, and rectify, its sources in sewerage systems. This paper describes exfiltration test apparatus and a series of experiments undertaken using sewage to gain a better understanding of the influence of sewage solids and sediments on leakage rates. An overview of the results obtained is given, which demonstrates that most previous estimates of exfiltration leakage rates were too high due to a lack of appreciation of the “self-repairing” action of sewage and sewage associated solids. Exfiltration rates of 0.1% of the sewer flow or 0.001 l/s have been recorded for defects up to 6 mm wide.
Comparison of radar and raingauge measurements during heavy rainfall
Authors: Einfalt T. , Jessen M. , Mehlig B.
Published: May 2018

Five heavy small-scale rainfall events in North Rhine-Westphalia (Germany) were investigated with radar and raingauge data. Special attention was paid to quality check and adjustment of radar data. Attenuation effects could be observed on both, C-Band and on X-Band radar. Adjustment of radar data to raingauge values turned out to be very difficult in the vicinity of heavy local rain cells. For the five affected regions the precipitation was quantified in the form of areal time series and cumulated radar images. As further result of this project, the spatial extent of the precipitation fields was identified and compared with radar and raingauge data.
Quantitative and qualitative hydrologic balance for a suburban watershed with a separate sewer system (Nantes, France)
Authors: Ruban V. , Larrarte F. , Berthier M. , Favreau L. , Sauvourel Y. , Letellier L. , Mosisni M.-L. , Raimbault G.
Published: May 2018

A qualitative and quantitative budget at the outlet of the storm-water runoff system of a small suburban watershed is presented together with some data regarding waste-water. 445,000 m3 (34% of the rain-water volume) were drained by the storm-water runoff system and 40,879 m3 by the waste-water system from September 2002 to March 2004. Storm-water runoff is generally not heavily polluted with regard to trace metals but concentrations occasionally exceed the standards for surface water of good quality. On the contrary, pesticides (diuron and glyphosate) have very high concentrations especially in spring and autumn when their use is maximum. As the St Joseph storm-water runoff is finally discharged into the Erdre River, measures to reduce the use of these pollutants should be considered.
Suspended solids transport: an analysis based on turbidity measurements and event based fully calibrated hydrodynamic models
Authors: Langeveld J.G. , Veldkamp R.G. , Clemens F.
Published: May 2018

Modelling suspended solids transport is a key issue for predicting the pollution load discharged by CSOs. Nonetheless, there is still much debate on the main drivers for suspended solids transport and on the modelling approach to be adopted. Current sewer models provide suspended solids transport models. These models, however, rely upon erosion–deposition criteria developed in fluvial environments, therewith oversimplifying the sewer sediment characteristics. Consequently, the performance of these models is poor from a theoretical point of view. To get an improved understanding of the temporal and spatial variations in suspended solids transport, a measuring network was installed in the sewer system of Loenen in conjunction with a hydraulic measuring network from June through December 2001. During the measuring period, 15 storm events rendered high-quality data on both the hydraulics and the turbidity. For each storm event, a hydrodynamic model was calibrated using the Clemens' method. The conclusion of the paper is that modelling of suspended solids transport has been and will be one of the challenges in the field of urban drainage modelling. A direct relation of either shear stress or flow velocity with turbidity could not be found, likely because of the time varying characteristics of the suspended solids.
Hydrocarbons and heavy metals fixed to the lift station sediment of the Paris combined sewer network
Authors: Gasperi J. , Rocher V. , Celaudon T. , Moilleron R. , Chebbo G.
Published: May 2018

This work aims to characterise the pollutant loads fixed to the Lift Station (LS) sediments. Firstly, levels of n-alkanes, PAH and heavy metals (Fe, Zn, Cu, Pb and Cd) of LS sediments were assessed, and were found of the same order of magnitude as those reported for street runoff. In addition, investigations on LS sediment reveal that n-alkane distributions reflect the combination of biologic and petrogenic inputs, while PAH distributions indicate a major pyrolytic origin with traces of petrogenic contaminations. The metallic fingerprints also attest to the important contribution of road traffic emissions. Secondly, a comparison between LS sediment and the Gross Bed Sediment (GBS) pollutant contamination was established in order to optimize the in-sewer deposits management. For hydrocarbons, a similar contamination between both sediments is found. For the heavy metals, this comparison indicates a similar Fe and Zn content, while Pb, Cu and Cd contents differ. Indeed, LS sediment shows a higher Cu content, linked to the occurrence of intensive brake lining abrasion, compared with GBS, which reflects a higher Pb and Cd content, owing to the contribution of roof runoff. This result reveals the impact of specific inputs such as road traffic or roof runoff on the in-sewer sediments contamination, and provides a complete overview of the LS sediment contamination. This database could be used by the municipality to optimize their contaminated in-sewer sediment management.
Investigating the effect of storm events on the particle size distribution in a combined sewer simulator
Authors: Biggs C.A. , Prall C. , Tait S. , Ashley R.
Published: May 2018

The changes in particle size of sewer sediment particles rapidly eroded from a previously deposited sediment bed are described, using a rotating annular flume as a laboratory scale sewer simulator. This is the first time that particle size distributions of eroded sewer sediments from a previously deposited sediment bed have been monitored in such a controlled experimental environment. Sediments from Loenen, The Netherlands and Dundee, UK were used to form deposits in the base of the annular flume (WL Delft Netherlands) with varying conditions for consolidation in order to investigate the effect of changing consolidation time, temperature and sediment type on the amount and size of particles eroded from a bed under conditions of increasing shear. The median size of the eroded particles did not change significantly with temperature, although the eroded suspended solids concentration was greater for the higher temperature under the same shear stresses, indicating a weaker bed deposit. An increase in consolidation time caused an increase in median size of eroded solids at higher bed shear stresses, and this was accompanied by higher suspended solids concentrations. As the shear stress increased, the solids eroded from the bed developed under a longer consolidation time (56 hours) tended towards a broad unimodal distribution, whilst the size distribution of solids eroded from beds developed under shorter consolidation times (18 or 42 hours) retained a bi- or tri-modal distribution. Using different types of sediment in the flume had a marked effect on the size of particles eroded.
Detailed observation and measurement of sewer sediment erosion under aerobic and anaerobic conditions
Authors: Schellart A. , Veldkamp R. , Klootwijk M. , Clemens F. , Tait S. , Ashley R. , Howes C.
Published: May 2018

A greater understanding of the erosion behaviour of sewer sediments is necessary in order to reliably estimate the amount and nature of the sewer sediments released from deposits in sewers and transported either to waste water treatment plants or discharged into the environment. Research has indicated that microbial activity in sediment can influence the physical release of sediment from in-pipe deposits. This paper reports on a series of erosion tests in which sewer sediments from different sewer networks are kept under different environmental conditions and their resistance to erosion is examined. The erosion tests are carried out under aerobic and anaerobic conditions and two temperatures, one representing ambient sewer temperatures and a lower temperature that significantly suppresses bacterial activity.
Membrane bio-reactor for textile wastewater treatment plant upgrading
Authors: Lubello C. , Gori R.
Published: May 2018

Textile industries carry out several fiber treatments using variable quantities of water, from five to forty times the fiber weight, and consequently generate large volumes of wastewater to be disposed of. Membrane Bio-reactors (MBRs) combine membrane technology with biological reactors for the treatment of wastewater: micro or ultrafiltration membranes are used for solid-liquid separation replacing the secondary settling of the traditional activated sludge system. This paper deals with the possibility of realizing a new section of one existing WWTP (activated sludge+clariflocculation+ozonation) for the treatment of treating textile wastewater to be recycled, equipped with an MBR (76 l/s as design capacity) and running in parallel with the existing one. During a 4-month experimental period, a pilot-scale MBR proved to be very effective for wastewater reclamation. On average, removal efficiency of the pilot plant (93% for COD, and over 99% for total suspended solids) was higher than the WWTP ones. Color was removed as in the WWTP. Anionic surfactants removal of pilot plant was lower than that of the WWTP (90.5 and 93.2% respectively), while the BiAS removal was higher in the pilot plant (98.2 vs. 97.1). At the end cost analysis of the proposed upgrade is reported.
Spatial variability of trends in hydrological extremes induced by orographically enhanced rainfall events due to westerly atmospheric circulations
Authors: Pfister L. , Drogue G. , Poirier C. , Hoffmann L.
Published: May 2018

Since the mid 1970s, the number of days with westerly atmospheric circulations has strongly increased during winter months. As a consequence, rainfall totals, rainfall event duration and intensity have been subject to significant positive trends throughout the Mosel river basin. However, the trends identified through the non-parametrical test named Kendall's tau have shown to be spatially varying. The intensity of the trends appears to be directly linked to orographic obstacles that are well known to have a strong influence on average rainfall totals. A direct consequence of the changes having affected winter rainfall under westerly atmospheric circulations on the one hand and the spatial variability of these changes on the other hand, is a spatially varying positive trend in maximum winter streamflow. Thus, even though a clear large-scale change has affected winter rainfall over the past decades, its intensity is either strongly moderated or enhanced by orographic obstacles. The related changes in streamflow are directly dependent on the spatial variability of the changed rainfall characteristics.
A model for the movement of large solids in small sewers
Authors: Butler D. , Littlewood K. , Orman N.
Published: May 2018

An extensive series of experiments has been carried out to investigate the movement mechanisms and behaviour of large solids in small sewers. This paper describes the development, calibration and verification of a model (SOLID) based on data obtained from the experimental rig. It is used to predict solid movement with respect to ‘limiting solid transport distance’. Key model parameters are the coefficients of static and dynamic friction, the shape factor of amorphous solids and the flow bypass coefficient. The model is shown to successfully represent the movement of a large solid down a small pipe, where the solid is moving as a sliding, leaking dam, particularly the first ‘hop’. Limitations of the model include a limited facility to well represent multiple hops and the need for closely spaced computational nodes leading to small time steps, and long run times.
Adaptation for river basins: connecting policy goals to the water resources system
Authors: Aerts J.
Published: May 2018

This paper focuses on a methodology called ‘generic adaptation methodology for river basins’ (AMR) that provides guidance to water managers seeking: (1) potential adaptation measures to climate change and climate variability, (2) measuring impacts, and (3) evaluating adaptations. The methodology uses basic elements addressed in existing adaptation research and is designed for a participatory setting involving various stakeholders. In AMR, the water resources system is seen as an economic asset that provides ‘goods and services’ for both humans and ecosystems. The innovative aspect of AMR is that it distinguishes impacts to water management objectives and impacts to the physical state of water resources in a river basin in a relatively simple iterative approach. Both impact types are quantified using indicators. The framework and results are demonstrated for a case study in the Walawe basin (Sri Lanka). It is explained that actually implementing adaptations in policy making can be difficult in trans-boundary river basins as each riparian country has its own policy objectives and hence ways of dealing with adaptation.
Biodegradability and biodegradation kinetics of creosote compounds in a biofilm in a fractured clay flow model
Authors: Arvin E. , Broholm K. , Gundog A. , Nielsen R.M.V.
Published: May 2018

If contaminated sites are situated in moraine clay areas, there may be a risk that the leachate is penetrating fractures to the underlying groundwater and thereby compromising the water quality. This study addresses the biodegradability and biodegradation kinetics of creosote compounds in a model fracture system. Eleven compounds typical of the water-soluble fraction of creosote were added to a mineral medium, each in a concentration of 0.5–1 mg/L: phenol, o-cresol, 2,4- and 3,5-dimethylphenol, naphthalene, 1-methylnaphthalene, 2,3-dimethylnaphthalene, indole, quinoline, benzothiophene, and dibenzofuran. The total concentration was around 7 mg/L. All the compounds were removed biologically by a biofilm in the model fracture under aerobic conditions. The compounds could be divided into readily biodegradable, moderately biodegradable and partly biodegradable compounds. The first order surface removal rates, k1,a, were in the range 0.02–0.1 m/d.
A 3D model of antimicrobial action on biofilms
Authors: Hunt S.M. , Hamilton M.A. , Stewart P.S.
Published: May 2018

A three-dimensional cellular automata model of biofilm dynamics was adapted to simulate the protection from killing by antimicrobial agents afforded to microorganisms in the biofilm state. The model incorporated diffusion and simultaneous utilization of a single substrate, growth and displacement of cells, detachment, and killing by an antimicrobial agent. The rate of killing was assumed to be directly proportional to the local concentration of substrate available to the microorganisms. Some of the features predicted by this model included development of dynamic, heterogeneous biofilm structures, gradients in substrate concentration leading to regions of substrate depletion in the interior of large cell clusters, variable killing by an antimicrobial agent from one simulation to the next, greater killing of cells at the periphery of cell clusters compared to those cells which were more deeply embedded, and reduced overall antimicrobial susceptibility of cells in the biofilm. These simulations show that substrate limitation can contribute to the protection from antimicrobial agents in biofilms but cannot explain the long-term persistence of biofilm viability that is often observed in practice.
Quantification of detachment forces on rigid biofilm colonies in a roto-torque reactor using computational fluid dynamics tools
Authors: Sudarsan R. , Milferstedt K. , Morgenroth E. , Eberl H.J.
Published: May 2018

External detachment forces acting on evenly spaced biofilm colonies grown in a roto-torque reactor are calculated numerically using a finite element based 2-D CFD tool. The 2-D laminar shear flow around a biofilm colony is investigated for different shear rates corresponding to different rotating velocities of a roto-torque reactor. The effect of neighbouring biofilm colonies is accounted for by the choice of boundary conditions for the flow model. The forces acting on the biofilm colonies show an initial gradual increase as the spacing decreases from a large value up to a particular spacing beyond which they decrease rapidly with decreasing spacing. This trend is highly correlated with the detailed structure of the flow around the biofilm colonies.
Comparison of spatial organization in top-down- and membrane-aerated biofilms: a numerical study
Authors: Bell A. , Aoi Y. , Terada A. , Tsuneda S. , Hirata A.
Published: May 2018

The study of community structure in wastewater biofilms is made difficult by the slow growth rates and high environmental sensitivities of autotrophic nitrifiers. Simulations of such films can generate data quickly and without susceptibility to random environmental perturbation. This study uses a 2D cellular automaton model to compare the community structures of biofilms grown under top-down and membrane aeration conditions. This study found dramatic differences in community structure between the two approaches, most notably the emergence of a niche at the solid–biofilm interface that facilitates the growth of nitrite oxidizing bacteria.
A survey of endocrine disrupting chemicals in sewage and a preliminary treatment trial
Authors: Jiang J.Q. , Yin Q. , Pearce P. , Zhou J.
Published: May 2018

This paper demonstrates that synthetic endocrine disrupting chemicals (EDCs) (e.g. bisphenol-A) and natural EDCs (e.g. estrone and 17β-estradiol) were found in the crude sewage from two sewage treatment works. Conventional biological processes can lower EDC concentrations to several hundred nanograms per litre. Because natural EDCs (e.g. estrone and 17β1-estradiol) have biological activity and an adverse impact on the environment at extremely low concentrations (several tens of nanograms per litre), and because the existing wastewater/sewage treatment processes are not adequate to reduce natural EDC concentrations lower than 100ngL−1, further treatment after conventional biological processes is required. Preliminary trials with ferrate(VI) and electrochemical oxidation processes demonstrated that the former is more effective than the latter in reducing EDC concentrations, and that both the processes can effectively reduce EDCs to very low levels, ranging between 20 and 100ngL−1.
Workshop 2 (synthesis): principles for management of urban water services
Authors: Rouse M. , Blokland M. , Martin R. , Söderbaum P.
Published: May 2018

The main conclusion of the workshop was that there is a widespread need for reform in the water sector, with clear separation of policy, regulatory and service delivery functions in the management of urban water services.
Biofilms in an urban water distribution system: measurement of biofilm biomass, pathogens and pathogen persistence within the Greater Stockholm area, Sweden
Authors: Långmark J. , Storey M.V. , Ashbolt N.J. , Stenström T.A.
Published: May 2018

Distribution pipe biofilms can provide sites for the concentration of a wide range of microbial pathogens, thereby acting as a potential source of continual microbial exposure and furthermore can affect the aesthetic quality of water. In a joint project between Stockholm Water, the MISTRA “Sustainable Urban Water” program, the Swedish Institute for Infectious Disease Control and the Royal Technical University, Stockholm, the aim of the current study was to investigate biofilms formed in an urban water distribution system, and quantify the impact of such biofilms on potential pathogen accumulation and persistence within the Greater Stockholm Area, Sweden. When used for primary disinfection, ultra-violet (UV) treatment had no measurable influence on biofilm formation within the distribution system when compared to conventional chlorination. Biofilms produced within a model pilot-plant were found to be representative to those that had formed within the larger municipal water distribution system, demonstrating the applicability of the novel pilot-plant for future studies. Polystyrene microspheres (1.0μm) and Salmonella bacteriophages demonstrated their ability to accumulate and persist within the model pilot-plant system, where the means of primary disinfection (UV-treatment, chlorination) had no influence on such phenomena. With the exception of aeromonads, potential pathogens and faecal indicators could not be detected within biofilms from the Stockholm water distribution system. Results from this investigation may provide information for water treatment and distribution management strategies, and fill key data gaps that presently hinder the refinement of microbial risk models.
Estimation of biodegradation kinetic constants for aromatic derivates through aerobic batch experiments
Authors: Andreozzi R. , Cesaro R. , Gonnella A. , Marotta R. , Pirozzi F.
Published: May 2018

The kinetics of aerobic biodegradation were studied for 20 aromatic species by using sludges taken from a municipal sewage treatment plant. The reproducibility of the results is tested with respect to the period of collection of the sludges and the wastewater treatment plant where they were taken. The comparison of kinetic constants estimated for investigated chemicals allows evaluation of the effect on the reactivity due to the presence of single groups (i.e. −OH, −CH3, −Cl, −NO2) into the aromatic structures. The search for easy structure–reactivity relations is also attempted by using some group contributing methods.
Constructed wetland attenuation of nitrogen exported in subsurface drainage from irrigated and rain-fed dairy pastures
Authors: Tanner C.C. , Nguyen M.L. , Sukias J.P.S.
Published: May 2018

Nitrogen removal performance is reported for constructed wetlands treating subsurface drainage from irrigated and rain-fed dairy pastures in North Island, New Zealand. Flow-proportional sampling of inflow and outflow concentrations were combined with continuous flow records to calculate mass balances for the wetlands. Drainage flows from the irrigated catchment were 2.5–4 fold higher and N exports up to 5 fold higher per unit area than for the rain-fed catchment. Hydraulic and associated N loadings to the wetlands were highly pulsed, associated with rainfall, soil water status, and irrigation events. Transient pulses of organic nitrogen were an important form of N loss from the rain-fed landscape in the first year, and were very effectively removed in the wetland (>90%). Median nitrate concentrations of ∼10 g m−3 in the drainage inflows were reduced by 15–67% during passage through the wetlands and annual nitrate-N loads by 16–61% (38–317 g N m−2 y−1). Generation in the wetlands of net ammoniacal-N and organic-N (irrigated site) partially negated reduction in nitrate-N loads. The results show that constructed wetlands comprising 1–2% of catchment area can provide moderate reductions in TN export via pastoral drainage, but performance is markedly influenced by variations in seasonal loading and establishment/maturation factors.
River contract in Wallonia (Belgium) and its application for water management in the Sourou valley (Burkina Faso)
Authors: Rosillon F. , Borght P. Vander , Sama H. Bado
Published: May 2018

Inspired by the experience of a river contract in Wallonia (Belgium) since 1990, the implementation of a first river contract has been initiated in a West African country, Burkina Faso. This application is not limited to a simple transposition of the Walloon model. The Burkina context calls for adaptation to the local environmental and socio-economical realities with an adequate partnership management. The importance of the mobilization around this project of institutional partners, as well as local collectivities, agricultural producers and water users in general reveals the great expectations of the actors concerning this new tool of water participative management. But will the latter be equal to the task? A first assessment has been drawn up one year after the launch. During the first year of the project, a participative diagnostic was implemented but the understanding of basic notions of water management such as ‘river’ (not translatable in the local language), ‘watershed’, ‘contract’ were not obvious. After the identification of functions and uses of water in the basin, an environmental survey was started. This approach allows study with the river committees of the priority actions to be developed as a first project of restoration of the gallery forest alongside the stream to fight against desertification. This project of integrated and participative management of water at sub-basin level is a concrete example of solidarity and exchange know-how between North and South in the context of a sustainable development.
Combined sewer overflow emissions to bathing waters in Portugal. How to reduce in densely urbanised areas?
Authors: David L.M. , Matos J.S.
Published: May 2018

The current proposal for a revised European Directive concerning the quality of bathing water significantly increases the demands for the control of wet-weather discharges. A densely urbanised combined catchment was modelled for a 19-year long rainfall series in order to assess the current situation and to evaluate the benefits of potential solutions. Storage and advanced physical-chemical treatment of stormwater in the STP may significantly contribute for the reduction of the overflow volumes but reductions of the spill frequency under 2.5 spill days per bathing season are hardly obtained. This study reveals the severe strains that the local rainfall pattern may place on the control of the frequency of wet-weather discharges, pointing to serious technical, social and economical implications, at the local and at the national level, if the current proposal for a revised European Directive on Bathing Water is enforced.
Challenges in the implementation of the Water Framework Directive: case study of the alpine River Drau, Austria
Authors: Toffol S. De , Achleitner S. , Engelhard C. , Rauch W.
Published: May 2018

The paper explores a methodology for the definition of ecological water quality indicators on the basis of a case study on an alpine river in Austria. Further, it discusses a particular interpretation of the combined approach introduced in the European Union Water Framework Directive that allows violating emission regulations if cost-effective.
Development of an integrated analysis procedure for three-ways layout field surveys data in lakes
Authors: Kitpati S. , Fujii S. , Shimizu Y.
Published: May 2018

Lake water quality systems are extremely complex and every lake is characterized by many complicated interactions between biological, chemical and physical variables. One of the most important tasks of lake mechanism analysis is to examine the relations among important water quality variables and to describe such complicated relationships quantitatively, simply and practically. Lake Biwa was chosen as a target lake, where a periodic water quality investigation was conducted every month from 1979 at 50 sampling sites. The objective of this study is to establish an application procedure of three-ways layout data and to present a vision including its practical result, expecting that this vision may also provide a direction for further research. The results showed that (1) cluster analysis following the three-ways layout ANOVA method is very effective in presenting water quality variation, (2) correlation analysis of water quality indices in each effect of parameters and their interaction between two items verifies that their relationships in parameters are different due to different mechanisms. (3) An integrated analysis procedure was derived, potentially describing those data in forms which convey their important characteristics and reveal their significant relationship. The same approach of this analysis procedure could be possibly applied for other water quality indices in other lakes.
Sustainable water management in rural and peri-urban areas: what technology do we need to meet the UN Millennium Development Goals?
Authors: Wilderer P.A.
Published: May 2018

Installation of advanced urban water management systems is one of the most important first steps in the attempt to overcome poverty on earth, outbreak of diseases, crime and even terrorism. Because world wide application of traditional water supply, sewerage and wastewater treatment technology requires financial resources which are basically not available within a reasonable short time frame novel solutions must be found, developed and implemented. The combination of high-tech on-site treatment of the various waste streams generated in households, enterprises and industrial sites, and reuse of the valuable materials obtained from the treatment plants, including the purified water, is one of the options which is investigated by various groups of researchers and technology developers, nowadays. This concept may help meeting the UN Millennium Development Goals, provided people are ready to accept this new way of dealing with household wastes. Education is necessary to build up the foundation which modern water technology can be based upon. In parallel, tailored modifications are to be considered to satisfy the specific demands of local communities. In this context, female participation appears to be extremely important in the decision making process.
Mathematical modelling of small wastewater treatment plants: power and limitations
Authors: Philips N. , Heyvaerts S. , Lammens K. , Van Impe J.F.
Published: May 2018

Although mathematical modelling of biological wastewater treatment processes has proved to be valuable for large-scale WWTPs (wastewater treatment plants) little experience has been acquired in the mathematical modelling of small wastewater treatment plants. This paper seeks to evaluate the applicability of mathematical modelling on small systems, which are characterized by high fluctuations in organic and hydraulic loads and little possibility for control. In order to achieve this, the paper examines the different steps in a general modelling protocol. One important bottleneck for the general use of mathematical modelling of small systems that emerges is the frequent sampling and many analyses needed for characterization of the flows while its applicability is limited. On the other hand, the determination of the model structure of a small WWTP can be quite valuable. Experiments show that tracer tests should include tests with a highly varying influent flow rate to spot independent small internal flows as these can have a significant impact on the behaviour of peak concentrations throughout the system. In addition, the model structure determination can provide useful information on dead zones, short-circuiting and mixing behaviour in the plant.
Treatment of high strength wastewater with vertical flow constructed wetland filters
Authors: De Feo G. , Lofrano G. , Belgiorno V.
Published: May 2018

The aim of the present study was to evaluate the behaviour of vertical flow constructed wetlands to treat high strength wastewater. Influents were obtained mixing tap water with different percentages of MSW landfill leachate (5%, 10% and 20%). Phragmites australis seedlings were used as macrophytes. The reeds were nurtured during three spring months, before the start of the experimental period. Three and four days of detention time were adopted. Influent concentrations of 510–2,050 mg L−1, 180–740 mg L−1 and 65–260 mg L−1 were obtained for COD, N–NH4+ and N–NO3−, respectively. The environmental temperature averaged around 31.0±1.4 °C. During the experimental period, all parameters showed an increasing removal efficiency trend. Best results in terms of COD removal were obtained for mixtures at lowest rate of landfill leachate; while, denitrification process showed an opposite behaviour; finally, the removal of ammonia nitrogen appeared to be independent upon influent concentrations. Analysis carried out on the reed tissues showed a theoretic maximum storage of TKN in the leaves of about 55 mg/g dry weight. A leachate percentage of about 35% was derived to be able to fully inhibit the growth of macrophytes.
Microbiological studies of an anaerobic baffled reactor: microbial community characterisation and deactivation of health-related indicator bacteria
Authors: Lalbahadur T. , Pillay S. , Rodda N. , Smith M. , Buckley C. , Holder F. , Bux F. , Foxon K.
Published: May 2018

This WRC funded project has studied the appropriateness of the ABR (anaerobic baffled reactor) for on-site primary sanitation in low-income communities. A 3,000 L pilot reactor was located at the Kingsburgh wastewater treatment plant south of Durban, South Africa. Feed to the reactor was raw domestic wastewater containing a significant proportion of particulate organic matter. The compartments of the ABR were routinely monitored for pH, COD, and gas production, among other physical-chemical determinants. The microbial population in each compartment was analysed by fluorescent in situ hybridisation, using general oligonucleotide probes for eubacteria and archeae and a suite of 10 genera or family specific probes. Scanning electron microscopy was conducted on the sludge fraction of each compartment. Mixed fractions from each compartment were also analysed for health-related indicator bacteria (total coliforms and E. coli). Results indicated that methanogenesis was not occurring to the expected extent in the latter compartments, and that this was probably due to a hydraulic load limitation. This contrasted with earlier studies on industrial effluent, for which the organic load was exclusively in soluble form. Inactivation of health-related indicator bacteria was less than 1 log, indicating the need for an additional post-treatment of the effluent to protect community health.
The effect of nitrogen loading on on-site system design: a model for determining land application area size
Authors: McCardell A. , Davison L. , Edwards A.
Published: May 2018

Designers of on-site wastewater management systems have six opportunities to remove pollutants of concern from the aqueous waste stream before it reaches ground or surface waters. These opportunities occur at source, at point of collection (primary treatment), secondary treatment, tertiary treatment, land application and buffers. This paper presents a computer based model for the sizing of on-site system land application areas applicable to the Lismore area in Northern New South Wales, a region of high rainfall. Inputs to the model include daily climatic data, soil type, number of people loading the system and size of housing allotment. Constraints include allowable phosphorus export, nitrogen export and hydraulic percolation. In the Lismore area nitrogen is the nutrient of most concern. In areas close to environmentally sensitive waterways, and in dense developments, the allowable annual nitrogen export becomes the main factor determining the land application area size. The model offers system designers the opportunity to test various combinations of nitrogen attenuation strategies (source control, secondary treatment) in order to create a solution which offers an acceptable nitrogen export rate while meeting the client's household and financial needs. The model runs on an Excel spreadsheet and has been developed by Lismore City Council.
Evaluation of recirculating sand filter in a cold climate
Authors: Christopherson S.H. , Anderson J.L. , Gustafson D.M.
Published: May 2018

Approximately 30% of Minnesota's residents rely on onsite technologies for their wastewater treatment. There is a growing need for ‘alternative, technologies to aid in treatment for difficult sites and sensitive environmental areas. Recirculating sand filters (RSFs) have been used since the 1970s for small communities with flows >20,000 L per day, but use for small flow application (<5,000 L/d) has been growing due to its small land use requirement.

A research site was developed in southern Minnesota in 1995 to test alternative technologies, including two RSFs. In addition, in 1998, two RSFs were added to existing residential soil treatment systems that were having problems because of inadequate separation and fill soil conditions. All RSFs in this study used 0.6 metres of coarse sand for treatment, were loaded at approximately 204 L per day per square metre (5 gallons per square foot per day) and a recirculation rate of 5:1. All RSFs have effectively reduced Biochemical Oxygen Demand (BOD5), Total Suspended Solids (TSS), Fecal Coliform (FC) and Nutrients (nitrogen and phosphorus). These systems are able to achieve secondary effluent treatment levels for BOD5 and TSS. The median FC reduction was 90% with a value of 5.7 E4 cfu/100 mL, indicating additional treatment is necessary to protect health and the environment. The RSFs consistently removed 25% or more total phosphorus (TP) and 40% or more total nitrogen (TN). The RSFs did not show significantly decreased performance during the winter months. Two of the RSFs receiving rather high strength domestic waste were able to reduce a greater percentage of total nitrogen, indicated that the addition of carbon from the high strength waste is a benefit resulting in greater TN removal.
An overview of the Central Queensland University self-contained evapotranspiration beds
Authors: Kele B. , Midmore D.J. , Harrower K. , McKennariey B.J. , Hood B.
Published: May 2018

The Central Queensland University (CQU) has championed a self-contained concrete lined evapotranspiration channel. Any non-transpired effluent returns to a holding tank and is recirculated through the evapotranspiration channel until it is used. This paper examines the results from the Rockhampton trial site. Nutrient ions in the effluent were quantified over time and found not to accumulate in solution. Microbial analysis of the treated effluent was performed and was found to be within the ranges required by the relevant legislative codes. Citrus fruit grown in the evapotranspiration channel were sampled and no elevated levels of faecal coliforms were recorded. Macronutrients and micronutrients of the soil in the channels were measured over a 5-year period. No toxic accumulations or nutrient deficiencies in the soil occurred. Levels of salinity and sodicity in the evapotranspiration channel soil were quantified. Salinity rose slightly, as did sodium. Concentrations of salts and sodium did not reach unsustainable levels. The aim of the trial was to develop an on-site treatment and reuse system that is sustainable and protects public and environmental health.
Multivariate statistical assessment of the pollution sources along the stream of Kamchia River, Bulgaria
Authors: Mihailov G. , Simeonov V. , Nikolov N. , Mirinchev G.
Published: May 2018

Sixteen sampling sites along the stream of Kamchia River were considered as environmental objects in the multivariate statistical study aimed to identify and apportion patterns of sampling sites, latent factors responsible for the data structure and their relation to the emitter industrial and anthropogenic sources in the vicinity of the sampling sites. As variables 11 surface water parameters monitored for a long time period (up to 11 years) were used. Four main site patterns were revealed by cluster analysis (urban, rural, near-to dam and estuary) and for each site latent factors were identified and apportioned (among them “metallurgical”, “food production”, “winery”, domestic wastes”, “natural”). The relative contribution of each identified pollution source to the formation of the total concentration of each chemical species or physicochemical parameter was determined and compared to the real emitters in the region of interest.
Legal aspects of sea water quality: Turkish and EU directives
Authors: Dolgen D.
Published: May 2018

This paper primarily addresses underlying laws and regulations related to protection of the coastal environment and examines their implementation. In this context, Directive 76/160/EEC which is the leading directive on the quality of bathing water and its revision, i.e. Commission Proposal COM (2000) 860 Final, is investigated particularly and criticized on technical and scientific manner; and similar and dissimilar issues between the Community Directives and Turkish Laws are evaluated. The conducted study reveals that although the Turkish legislation in the field of water quality is largely in line with the acquis, further efforts are also needed with respect to implementation in order to achieve full harmonization.
Implementing the Water Framework Directive in Bulgaria: integrated river basin management on the Black Sea coast
Authors: Pratt A. , Lønholdt J. , Jørgensen P.E. , Persson B. , Nikolov V. , Ianev R. , Dontchev V. , Klint M.
Published: May 2018

EC member states and candidate countries are in the process of implementing the requirements of the EC Water Framework Directive 2000/60,[Q1] which came into force on 22 December 2000. At the core of the Directive is an integrated approach for sustainable water management in river basin districts. The overall objective is to reach good water status for all waters by the year 2015. The challenges for countries implementing the Directive are substantial not least for the River Basin Management Authorities who will be the implementing unit at the regional level. The Black Sea River Basin Directorate in Varna is one of four Directorates established in Bulgaria in 2002 in accordance with the Bulgarian Water Act and is the regional operational unit under the Ministry of Environment and Water for the Black Sea Basin catchment area. The catchment area covers 20% of Bulgaria and 100% of the Bulgarian Black Sea coast. Current implementation activities in the Black Sea Basin Directorate and also at the national level are supported by the Danish EPA through its DANCEE programme in collaboration with the Ministry of Environment and Water. This paper highlights the main activities and outputs of the technical and institutional undertakings in the Black Sea Basin Directorate focusing on the preparation of the River Basin Overview by Dec. 2004.
Evaluation of denitrification potential of rotating biological contactors for treatment of municipal wastewater
Authors: Hanhan O. , Orhon D. , Krauth Kh. , Günder B.
Published: May 2018

In this study the effect of retention time and rotation speed in the denitrification process in two full-scale rotating biological contactors (RBC) which were operated parallel and fed with municipal wastewater is evaluated. Each rotating biological contactor was covered to prevent oxygen input. The discs were 40% submerged. On the axle of one of the rotating biological contactors lamellas were placed (RBC1). During the experiments the nitrate removal performance of the rotating biological contactor with lamellas was observed to be less than the other (RBC2) since the lamellas caused oxygen diffusion through their movement. The highest nitrate removal observed was 2.06 g/m2.d achieved by a contact time of 28.84 minutes and a recycle flow of 1 l/s. The rotation speed during this set had the constant value of 0.8 min−1. Nitrate removal efficiency on RBC1 was decreasing with increasing rotation speed. On the rotating biological contactor without lamellas no effect on denitrification could be determined within a speed range from 0.67 to 2.1 min−1. If operated in proper conditions denitrification on RBC is a very suitable alternative for nitrogen removal that can easily fulfil the nutrient limitations in coastal areas due to the rotating biological contactors economical benefits and uncomplicated handling.
Evaluation of the performance of the Tyson Foods wastewater treatment plant for nitrogen removal
Authors: Ubay-Cokgor E. , Randall C.W. , Orhon D.
Published: May 2018

In this paper, the performance of the Tyson Foods wastewater treatment plant with an average flow rate of 6500 m3/d was evaluated before and after upgrading of the treatment system for nitrogen removal. This study was also covered with an additional recommendation of BIOWINTM BNR program simulation after the modification period to achieve an additional nutrient removal. The results clearly show that the upgrading was very successful for improved nitrogen removal, with a 57% decrease on the total nitrogen discharge. There also were slight reductions in the discharged loads of biological oxygen demand, total suspended solids, ammonium and total phosphorus with denitrification, even though the effluent flow was higher during operation of the nitrogen removal configuration.