bluuebunny/crossref_metadata_2025 huggingface dataset:
Upflow biological filter: modeling and simulation of filtration
Authors: Le Tallec X. , Vidal A. , Thornberg D.
Published: May 2018

One of the most important operating parameters for the operation and the design of biofilters is the headloss due to clogging of the system leading to a semi-continuous operation with filtration cycles and backwashes. Some basic aspects of the filtration operation have been studied. The work consists in understanding and modelling the clogging phenomena due to the suspended solids retention, and validating the simulation results by calibration with experimental and full-scale results.

Tracer experiments allowed us to simplify the hydrodynamics within the Biofilters into a plug-flow reactor with axial diffusion. Mass balances for the suspended solids have been therefore written accordingly, including solids retention represented as a mass transfer from the liquid to the solid phase. This affects the porosity of the system, leading on one hand to a modification of the filtration coefficient (responsible for the transfer of SS from liquid to “solid” phase) and on the other hand to an increased clogging measured by the headloss in the system.

The Kozeny-Carman equation could successfully be used and a linear relationship between the filter coefficient and the water porosity could be validated. Experimental work has been conducted to calibrate the model and in this paper validations from pilot scale unit to full-scale plant are shown.
Modeling of aerated upflow fixed bed reactors for nitrification
Authors: Behrendt J.
Published: May 2018

A mathematical model for nitrification in an aerated fixed bed reactor has been developed. This model is based on material balances in the bulk liquid, gas phase and in the biofilm area. The fixed bed is divided into a number of cells according to the reduced remixing behaviour. A fixed bed cell consists of 4 compartments: the support, the gas phase, the bulk liquid phase and the stagnant volume containing the biofilm. In the stagnant volume the biological transmutation of the ammonia is located. The transport phenomena are modelled with mass transfer formulations so that the balances could be formulated as an initial value problem. The results of the simulation and experiments are compared.
Dynamic simulation of a low loaded trickling filter for nitrification
Authors: Seggelke K. , Obenaus F. , Rosenwinkel K.-H.
Published: May 2018

For this report, an existing biofilm model was examined in regard to its suitability for the simulation of full scale trickling filter for nitrification. The system was calibrated using the results ascertained in a measuring campaign under dry weather conditions. The verification was done using the results of a second examination period which included spells of stormwater input. It was possible for all periods to satisfactorily illustrate the degradation performance of the simulated trickling filters in regard to dynamics and quantity.
Modelling and reliability analysis of water distribution systems
Authors: Tanyimboh T. T. , Burd R. , Burrows R. , Tabesh M.
Published: May 2018

This paper describes pressure-driven simulation and highlights the important role that it plays in the management of water distribution systems. Two cases are described for a real water distribution system of about 5,100 nodes serving a population of approximately 44,000. One case involves the simulation of the effects of the failure of a major system component. The other case is concerned with the capacity of the distribution system with reference to growing demands over a planning horizon spanning two decades. The examples considered demonstrate the primacy of pressures in water distribution systems and highlight some of the shortcomings of demand-driven methods for analysing water distribution systems.
Dynamic control of the Delfland polders and storage basin, The Netherlands
Authors: Lobbrecht A. H. , Sinke M. D. , Bouma S. B.
Published: May 2018

In regional water systems such as those in the Netherlands, a large number of interests with commonly conflicting requirements are involved. Dynamic control offers a way of controlling these complex water systems, making use of the dynamics of the water system. Dynamic control can deal with the entire water-related environment, including all different interests present. This advanced control technique is based on optimization and achieves more efficient operation of a water system because all capacities available in the system can be fully used.

When new requirements of any interests in a water system emerge, the traditional solution is to build new water-management infrastructure or extend the existing infrastructure. The application of advanced control techniques shows that this may not always be necessary.

For the Delfland water system, a case study shows how dynamic control can be used to balance the interests present and continually match the water system state with the requirements. The case described demonstrates how dynamic control can be used to reduce undesirable water-system behavior during periods of excessive precipitation or drought.

Current town and country plans imply an increase in the impervious surface in Delfland in the near future. If the current control practice continues, installation of extra capacity at existing drainage pumping stations would be needed, or even construction of entirely new pumping stations or extra storage facilities. Application of dynamic control makes it possible to use the current capacities in the water system more efficiently and thus avoid large capital investment which otherwise would be necessary in the future.
Water as a transport medium for waste out of towns
Authors: Harremoës P.
Published: May 2018

The historical background for centralised water management in the cities of the developed world is outlined in order to give the rationale for the technical solutions we have inherited from the last century. The key element is maintaining the hygienic conditions in the cities. The success is illustrated by the absence of water-borne diseases in the modern developed city. A new paradigm is introduced based on added concern for the use of resources, pollution of the environment and the concern for the welfare of the coming generations. The water resource is not the unsustainable aspect of urban water use, because water is not lost, but polluted, which can be abated. Water can be re-routed and recycled. There are many attractive local solutions for better handling of urban water.
Consumption and domestic waste water demographic factors and developments in society
Authors: van der Wijst M. A. J. E , Groot-Marcus J. P.
Published: May 2018

Different types of households can be distinguished but as all households consume, they all contribute to the pollution of domestic waste water. The consumption of households is liable to changes, which lead to the problem definition of this paper: What are the influences of household characteristics and changes in consumption on the pollution of domestic waste water in terms of oxygen demand? To answer this question a literature research was conducted by which data from different research fields is collected, analysed and integrated. The factors that influence the oxygen demand of domestic waste water can be divided into personal and household factors. The results of this survey show that the personal factor, and especially physiological waste products, is most important, as it accounts for 60% of the oxygen demand of domestic waste water. This factor also contributes most of the changes of oxygen demand of domestic waste water, while behaviour and demographics have little effect.
The impact of rainwater reuse on CSO emissions
Authors: Vaes G. , Berlamont J.
Published: May 2018

The increasing consumption of drinking water puts a heavy burden on our future water resources. Therefore the reuse of rain water in households can be a good option to tackle this problem. On the other hand the rapidly drained rain water leads to problems in the combined sewer systems and watercourses. If the storage in the rain water tanks can be used to flatten the rain water runoff, rain water tanks can have an additional benefit. The effect of rain water tanks on the combined sewer overflow (CSO) emissions is therefore investigated with a reservoir model. Compared with storage in the combined sewer system or at the overflow, storage in rain water tanks will be more efficient in reducing the overflow emissions. However much more storage in rain water tanks must be provided to obtain the same overflow frequency as when downstream storage is used, because the storage in rain water tanks is less frequently available. When all the economical, social and environmental aspects are considered, rain water tanks can certainly be promoted as a good solution.
Transfer and acceptance of UASB technology for domestic wastewater: two case studies
Authors: Kalker T. J. J. , Maas J. A. W. , Zwaag R. R.
Published: May 2018

The non-technical factors that played a role in the transfer and acceptance of the UASB technology for domestic wastewater are identified and discussed for two case studies. In Cali, Colombia, a full scale plant was implemented in a residential area within the framework of a relatively small project. The fact that in the early developing stage of the technology a large amount of UASB reactors were realized in an uncontrolled way, affected the acceptance of the technology negatively, as did also the odour problem that arose at the demonstration plant. In India, where the UASB technology was introduced in the framework of a large governmental environmental programme with a considerable amount of technical support, this technology is at present broadly accepted. Therefore, involvement of policy makers and strengthening of human resources by intensive technical support are considered important factors when transferring technology. For a further dissemination of the technology, appropriate lending practices of financial agencies are considered as crucial as well as providing the institutional requirements to realize revenue collection.
A Simplified Method to Determine The Powdered Activated Carbon Dose Required to Remove Methylisoborneol
Authors: Gillogly Thomas E. T. , Snoeyink Vernon L. , Newcombe Gayle , Elarde Joseph R.
Published: May 2018

Equilibrium data obtained from a natural water with several different initial concentrations of 2-methylisoborneol (MIB) plot as a single line on a percent remaining, Ce/Co × 100%, versus carbon dose, Cc, plot. This indicates that the percent removal of MIB is independent of its initial concentration in natural water for a given PAC dose. The relationship is specific for each type of PAC, and it is not valid at very high MIB concentrations, however. These data show that, predicting the minimum amount of carbon necessary to effectively mitigate any MIB episode, may be accomplished by analyzing a single bottle-point isotherm. The robustness of this approach was shown through the use of four water sources, fourteen different carbons, and MIB concentrations ranging from 45 ng/l to 178 μg/l.
Recent Advances in Mechanisms of Odor Perception
Authors: Holley André
Published: May 2018

This paper summarizes recent findings on the olfactory system and on its functioning. Studies in molecular biology indicate that odor receptors are extremely numerous and diverse. These remarkable findings, along with recent data on the functional organization of the olfactory bulb and cortex, provide a framework for revisiting traditional views on odor coding. Both spatial and temporal neural codes seem to participate in the representation of odors in the olfactory system.
Off-Flavor Problems in Two Reservoirs, Associated with Planktonic Pseudanabaena Species
Authors: Izaguirre G. , Taylor W. D. , Pasek J.
Published: May 2018

In the summer of 1996, off-flavor episodes involving 2-methylisoborneol (MIB) occurred in two southern California reservoirs: San Vicente Reservoir, in the San Diego area, and Lake Skinner, in western Riverside County. These events resulted in many consumer complaints from the respective communities served. During the San Diego episode, moderate numbers of Pseudanabaena and other plankton were present in the water, and MIB was detected in one sample at 23 ng/l. Two strains of Pseudanabaena that produced MIB were isolated; cultures of this organism yielded 22 and 23 μg/l, respectively. Lake Skinner water also contained a moderate number of Pseudanabaena and other plankton when MIB levels began to rise, with MIB reaching 10 ng/l. Liquid and agar cultures derived from Lake Skinner water developed a strong MIB odor, and eventually three MIB-producing isolates were obtained. MIB levels in the cultures were all less than 1 μg/l. This was the first known MIB episode of planktonic origin in Lake Skinner, and it was the first off-flavor event in either reservoir in which Pseudanabaena was implicated. These two events underscore the potential importance of an organism not generally recognized as a cause of off-flavor in water supplies.
Characterization of Oscillatoria F. Granulata Producing 2-methyl-isoborneol and Geosmin
Authors: Tsuchiya Y. , Matsumoto A.
Published: May 2018

We characterized the cyanobacterium Oscillatoria f. granulata isolated from water collected from a cooling tower in Tokyo, Japan. The O.f.granulata produced the earthy/musty odor-producing substances geosmin and 2-methylisoborneol (2-MIB). Chlorophyll a and the levels of both odor compounds were markedly increased at 1000 lux compared to those at 500 and 2000 lux illumination. After a 40-day incubation, 338g/l of 2-MIB and 5.9g/l of geosmin were found in the No.11 culture medium. With incubation in CT liquid medium, a level of 2-MIB that was 3.1 times higher than that in the No.11 culture medium was obtained. Metabolites in the culture of O.f.granulata were identified using atomic emission detector-gas chromatography (AED-GC) and gas chromatography/mass spectrometry (GC/MS). The AED-GC analysis revealed many peaks containing C, H, O atoms as well as 1 peak of nitrogen on the GC chromatogram, but there were no chlorine-, bromine- or sulfur-containing peaks. The GC/MS analysis identified 6 terpenoids (e.g., eudesmol and sesquiterpene alcohols), 3 phenols (e.g., phenol and BHT), 6 aldehydes (e.g., nonanal, decanal and undecanal), 8 fatty acids (e.g., penta-, hexa- and octadecanoic acid), 8 hydrocarbons (e.g., n-heptadecane, methyl heptadecane and octadecane) and phytol.
Development of a Standard Method – Analysis of Compounds Causing Tastes and Odors in Drinking Water
Authors: Young Connie C. , Suffet I. H. (Mel)
Published: May 2018

A standard method for analyzing 22 off-flavors in drinking water was developed. It includes chemical analysis - CLSA and SDE coupled with GC-MS, and sensory techniques - FPA and sensory GC analysis. Trans, trans-2,4-Heptadienal, a newly found fishy causing compound, was studied for its detection limit and OTC. Two grassy causing compounds, cis-3-hexen-1-ol and cis-3-hexenyl acetate, were also evaluated.
The Formation, Stability, and Odor Characterization of 2-ethyl-4-methyl-1,3-dioxolane (2-EMD)
Authors: Schweitzer L. , Noblet J. , Ruth E. , Suffet I. H.
Published: May 2018

A class of compounds which are byproducts of the resin manufacturing process, has been responsible for three different taste and odor episodes in drinking water around the world. One such episode which occurred on the Ohio River, Pennsylvania, USA in 1989 was linked to the chemical, 2-ethyl-4-methyl-1,3-dioxolane (2-EMD). In this study, the mechanism and kinetics of formation of 2-EMD were examined specifically under the conditions which were present in the waste water of a resin manufacturer during the Ohio River event. The stability (fate) of 2-EMD was studied at aqueous pHs of 3, 5, 7, and 9. Hydrolysis occurred on the order of hours at pH 3 and its stability was questionable even at pH 7, but appeared to be stable at pH 9. 2-EMD was synthesized and purified in order to determine odor characteristics and odor thresholds using the method of flavor profile analysis (FPA). The distinctive sweet odor described as “sickening sweet” or “medicinal sweet” was found to have an odor threshold concentration of between 5 and 10 ng/l. The levels of 2-EMD found in drinking water samples from the taste and odor event of the Ohio River were above this odor threshold.
The Quality of Marine Water Around a Sewage Outfall
Authors: Al-Muzaini S. , Beg M. , Muslamani K. , Al-Mutairi M.
Published: May 2018

A major sewage outlet located close to Shuwaikh Harbor discharges raw and treated water from the Al-Ardhiya sewage treatment plant, as well as raw sewage from a pumping station. It also receives input from Kuwait International Airport. The area has been spotted for its characteristic foul smell mainly because of stagnant water at the outlet. Therefore, samples were collected from eleven fixed stations at high tide and six stations at low tide to examine water quality parameters, NO3, NO2, NH3, SO4, S2, PO4, BOD, COD, TOC and heavy metals Pd, V, Cd, Ni, Mn, Cr, Cu, and total fecal coliform. The results of the physical and chemical analyses for both high-and low-tide samples along with microbiological analyses indicate that the Shuwaikh marine area is polluted. The pollution is high near the discharge point and decreases with distance. The data revealed a lower level of chemical pollutants and fecal counts at high tide than at low tide. This is mainly because of the dilution caused by incoming seawater at high tide. Although tidal movement helps reduce pollution in the area, for improvement of the situation to the desired level, biological wastewater treatment is suggested to remove most of the organic matter before discharge. Also, extension of the discharge outfall pipe to the open sea area would help reduce trapping of effluent in the coastal region and check fouling in the area.
Utilization of Local Material in the Construction of an Embankment for Recharging Groundwater Aquifer with Treated Wastewater Effluents
Authors: Aiban S. A. , Ishaq A. M. , Al-Suwaiyan M. S.
Published: May 2018

Water is certainly the most precious and valuable resource of the physical environment for all living creatures. It is now well established that in many agricultural regions in the Kingdom of Saudi Arabia, the water table has been depleted dramatically. If the current level of agricultural production is to be maintained, other sources of agricultural water must be found. There is at least a billion cubic metres of secondary municipal effluent wasted annually. Thus, utilization of these wastewater effluents to recharge groundwater aquifers and reuse them at least for agricultural purposes becomes a viable proposition.

In the study reported herein, treated wastewater will be used to recharge aquifers using spreading basins. The basin consists of a dune sand filter confined, from all sides, by an embankment of compacted sand/marl material. A field site has been constructed in Al-Aziziyah in eastern Saudi Arabia. The sand filter is constructed from clean dune sand, has an area of 25 × 25 m, and has an effective height of approximately 7.0 m. The stability and permeability of the embankment were of primary importance, and its construction had been precisely controlled. The materials used in the construction are locally available. The characteristics of the materials, the construction procedures, and the stability analysis are presented in detail.
Complementary independent molecular, radioisotopic and fluorogenic techniques to assess biofilm communities in two wastewater wetlands
Authors: Flood Janine A. , Ashbolt Nicholas J. , Pollard Peter C.
Published: May 2018

Optimisation of nutrient removal processes requires a detailed understanding of the microbial physiologies actually occurring within the biomass of different treatment zones, and also knowledge of how these communities respond to environmental factors. This paper describes a suite of four independent and complementary, microbiological techniques, utilised to obtain detailed assessments of wastewater bacterial biomass. Examples of these techniques are shown as applied to biofilms from two surface-flow wetlands used for treating sewage effluent. Intact biofilms were prepared via freezing, followed by cryosectioning and direct microscopic observation. This approach was combined with prior, in situ incubation of biofilm with radiolabelled thymidine to assess in situ bacterial growth rates. Individual bacterial cells were assessed microscopically for in situ respiratory activity and phylogenetic identity, respectively through use of an inducibly-fluorescent redox stain (CTC), and fluorescent in situ hybridisation (FISH) of ribosomal RNA (rRNA). These complementary techniques enabled assessment of individual biofilm clusters according to their in situ status (growth, respiration, spatial location and phylogenetic affiliation). This approach detected significant spatial variations in biofilm; limited the bias inherent in data obtained using any one technique, and provided greater detail of subpopulations within the microbial community.
Phytoplankton Activities in Hypersaline, Anoxic Conditions. II—Photosynthetic Activity of some Sulphide Adapted Cyanobacterial Strains Isolated from Solar Lake, Taba, Egypt
Authors: Shabana Effat F. , Ali Gamila H.
Published: May 2018

Five cyanobacterial strains namely Oscillatoria limnetica, Aphanotheca stagnina, Synechococcus aeruginosus, Spirulina tenissima and Dactylococcopsis salina were isolated from an anaerobic sulphide rich hypersaline Solar Lake, Taba- Egypt. At oxygenic conditions Spirulina was the most tolerant strain to sulphide concentrations, while Aphanotheca and Synechococcus were the most sensitive. Aphanotheca have higher anoxygenic photoassimilation activity under a broad range of sulphide concentrations. The response of the five cyanobacterial strains to sulphide under oxygenic and anoxygenic conditions depends on the organism, time of exposure, presence or absence of DCMU and also on sulphide concentration.
Activity, structure, and stratification of membrane-attached methanotrophic biofilms cometabolically degrading trichloroethylene
Authors: Clapp Lee W. , Regan John M. , Ali Firdaus , Newman Jack D. , Park Jae K. , Noguera Daniel R.
Published: May 2018

A membrane-attached methanotrophic biofilm reactor was developed for the cometabolic degradation of trichloroethylene (TCE). In this reactor, CH4 and O2 are supplied to the interior of the biofilm through the membrane, while TCE-contaminated water is supplied to the exterior, creating a “counter-diffusional” effect that minimizes competitive inhibition between TCE and CH4. In addition, this novel design provides 100% CH4 and O2 transfer efficiencies, promotes the development of a thick biofilm, and minimizes the negative effects of TCE byproduct toxicity. The reactor sustained 80-90% TCE removals at TCE loading rates ranging from 100-320 μmol/m2/d. Chloride mass balances demonstrated that 60-80% of the TCE removed was mineralized. The maximum TCE transformation yield was 1.8 mmol of TCE removed per mole of CH4 utilized, although higher transformation yields are expected at higher TCE loading rates. The CH4 utilization rate was 0.20 mol/m2/d. Scanning electron microscopy (SEM) revealed a dense biofilm with a thickness of at least 400 μm. SEM and transmission electron microscopy (TEM) analyses indicated that the “holdfast” material associated with rosette formation in planktonic Methylosinus trichosporium OB3b (M.t. OB3b) cells might also contribute to pure-culture biofilm development. In addition, fimbriae-like structures not commonly associated with methanotrophic bacteria were observed in pure-culture M.t. OB3b biofilms. Finally, fluorescent in situ hybridization (FISH) analyses showed the presence of discrete microcolonies of serine-pathway methanotrophs within mixed-culture biofilms.
A novel method for evaluation of biofilm tensile strength resisting erosion
Authors: Ohashi Akiyoshi , Koyama Takashi , Syutsubo Kazuaki , Harada Hideki
Published: May 2018

A novel methodology is proposed in this study to evaluate the tensile strength of biofilms by using a newly developed tensile test device. Three different types of biofilms were prepared for tensile test: Run 1 biofilm was aerobically cultivated on glucose, and Run 2 and Run 3 biofilms were denitrifying biofilms grown on glucose and on methanol, respectively, as a sole carbon source. Each of three biofilms was formed on the outer surfaces of tygon-made tubes (diameter 4.76 mm) submerged in a rectangular open-channel reactor.

The results demonstrated that the tensile strengths of three different biofilms had a tendency to increase with the biofilm development over a period of 50 days of reactor operation and eventually reached a similar range, approximately 500 to 1000 Pa, independent of biofilm types or cultivation conditions. An elastic coefficient of the biofilm was determined by assuming that a biofilm behaves as an elastic material during the tensile test. A strong positive correlation was found between the elastic coefficient and the tensile strength. However, the behavior of extracellular biopolymer (ECP) content and the biofilm density were not dependent on the tensile strength. Scanning electron microscope (SEM) observations also suggested that the biofilm structural properties such as elastic coefficient are more determinative factors for the tensile strength than are the biofilm physiological properties such as ECP content.
Influence of So/Xo Ratio on Anaerobic Activity Test
Authors: Moreno Gloria , Cruz Arturo , Buitrón Germán
Published: May 2018

The effect of the substrate/microorganism ratio during the development of anaerobic activity test was studied. The experimentation was carried out in serum bottles at 35°C. Two sets of experiments utilizing acetate and an azo dye (blue disperse 79) as the sole source of carbon were studied. It was observed that mixing has an important influence on the results. The initial substrate concentration and the initial biomass concentration had a significant effect on the reaction rate and on the biomass yield coefficient, Yobs. Different kinetic coefficients were found for the case of equal So/Xo ratio, but different initial substrate concentration.
Two-phase anaerobic technology for domestic wastewater treatment at ambient temperature
Authors: Arsov R. , Ribarova I. , Nikolov N. , Mihailov G. , Topalova Y. , Khoudary E.
Published: May 2018

Anaerobic process phase separation was implemented in the present investigation, using two kinds of suspended anaerobic biomass – floccules and granules, respectively. Both phases of the process were proved to follow the classic Monod kinetics, the reported parameters of which indicate extremely high activity of the anaerobic biomass. This was achieved by providing appropriate hydrodynamic conditions in the bioreactors and creation of granulated (pelletized) biomass in the second one. The reasons and circumstances leading to these results are discussed, as well as the appropriate bioreactor construction schemes and the possibilities for implementation of the reported technology in practice and in coastal areas in particular.
Kinetics of removal of zinc ions from aqueous solutions by a modified acrylnitrile copolymer
Authors: Stefanova R. Y.
Published: May 2018

The kinetics of removal of zinc ions from aqueous solutions by a modified acrylnitrile copolymer containing carboxyl and amino groups has been investigated. The dependence of the rate of removal on the intensity of stirring, the size of the sorbent's particles, the initial concentration of metal ions and the temperature of the solution have been established. Attempts have been made to identify the rate limiting step and to determine the batch kinetic parameters. The limiting conditions of the transition from external to intraparticle diffusion step of mass transfer in a sorption system have been determined. The coefficients of intraparticle diffusion and the energy of activation of the sorption process have been established. The data obtained in this work show that the modified polymer with a high sorption capacity and very good kinetic characteristics can be successfully used for removal of heavy metal ions from water solutions and industrial wastewaters.
Ecological research on the Tzonevo dam as a possible alternative source for the water supply of Varna City
Authors: Zlatarova Savka , Slavtcheva Dora , Georgieva Bojanka
Published: May 2018

The objective of this research is an ecological estimation of the water qualities of the Tzonevo dam during the period between January 1997 and February 1998, in view of its use as a possible alternative source for the water supply of Varna city. We have analyzed and interpreted by physical, chemical, microbiological, hydrobiological and radiological indices the results of 80 samples, taken from 6 control points on the dam. The data obtained have been compared to those of the ecological estimation, performed by the same team in the period 1992-1993. We have attempted to make an ecological classification of the dam water and to qualify it in compliance with the norms effective in Bulgaria. In accordance with the ecological classification, the water meets the requirements for a 1st category water basin, with a fully preserved self-purifying capacity, providing the possibility for its use, after compulsory sanitary processing, as a possible alternative water supply for Varna city.
Anaerobic Treatment of Low, Medium and High Strength Effluent in the Agro-industry
Authors: Driessen W. , Yspeert P.
Published: May 2018

Based on the widely applied UASB system for anaerobic wastewater treatment a new generation of more advanced anaerobic reactor systems have recently been developed, according to the so-called expanded sludge bed concept. A successful version of this concept is the Internal Circulation (IC) reactor, characterized by the biogas separation in two stages within a reactor with a high height/diameter ratio and the gas-driven internal effluent circulation. The IC system can handle high upflow liquid and gas velocities, which makes treatment of low strength effluents at short hydraulic retention times, as well as treatment of high strength effluents at very high volumetric loading rates feasible. During the past years the IC technology has been successfully applied at full scale on a variety of industrial wastewaters. This article describes the design and operational results of three full scale anaerobic treatment plants with Internal Circulation reactors treating low, medium and high strength effluents from a dairy industry, food processing plant and brewery respectively.
Quo vadis sewer process modelling?
Authors: Ashley R. M. , Hvitved-Jacobsen T. , Bertrand-Krajewski J.-L.
Published: May 2018

Over the past decade, considerable investment has been made in acquiring knowledge about in-sewer processes, with the objective of developing new analytical tools to predict the performance of these systems. A wide variety of these tools have emerged, from simple aggregated conceptual models of entire systems, to very detailed physically based relationships for particular processes such as suspended transport. The major investors in this research have been determined to produce commercial models which will form part of integrated system analysis suites of software for use in the formulation of holistic and optimum managerial methods for wastewater systems. Unfortunately, sewer processes are extremely complex, and the very limited investment, when compared proportionately with that made in hydrological and hydraulic analysis over previous decades, has produced apparently gaps in underlying knowledge which are not generally acknowledged. This paper reviews the current position with regard to sewer process modelling, highlighting areas where knowledge is still deficient, and where new opportunities and limitations are emerging.
Drinking Water Distribution - the Effect of Natural Organic Matter (NOM) on the Corrosion of Iron and Copper
Authors: Broo A. Elfström , Berghult B. , Hedberg T.
Published: May 2018

The objective was to study the influence of natural organic matter (NOM) on the corrosion and by-product release of iron and copper. The corrosion was studied using potentiodynamic sweeps, coupon tests and field measurements in different Swedish municipalities. For iron it was found that the corrosion rate decreases in the presence of NOM. The results are explained in terms of surface complexation and a good correlation is found between theoretical calculations and experimental results. In the case of copper it was found that NOM both increases the corrosion rate and the content of copper in the water after one night of stagnation. The results are compared with equilibrium calculations and a good correlation is achieved.
A conceptual model for sediment transport in combined sewer systems
Authors: Schlütter Flemming
Published: May 2018

This paper presents a numerical model capable of simulating sediment transport in combined sewer systems. The main objectives of the model are to model mass transport rates at the outlet from a catchment and at the same time obtaining qualitative information on erosion and deposition going on at different locations in the sewer system. The model is conceptual but based on deterministic computations of hydraulic conditions. The formulations used in the conceptual model (STSim) are presented as well as results from a sensitivity analysis. Finally, an example is given of a calibration event from a case study.
First flush of dissolved compounds
Authors: Krebs Peter , Holzer Peter , Huisman Jacco L. , Rauch Wolfgang
Published: May 2018

In a crude conceptual approach it is commonly assumed that in a combined sewer system the concentration of dissolved compounds in diluted by an increasing flow rate due to rainwater inflow. However, theory of hydraulics suggests that these compounds are influenced by hydrodynamic effects. It is known that since the wave celerity is higher than the flow velocity of the water, the increase of flow rate induced through rain runoff is recognised earlier at a certain downstream section of the combined sewer than the concentration increase of typical rain-water compounds originating from surface wash-off. This description implies that the wave front is formed from the fluid that was present in the sewer before the flow rate increased, that is the sewage! By means of measurements and numerical simulations, it is shown that this effect may cause a significant impact of dissolved compounds on the receiving water, when a combined sewer overflow occurs, and also on the wastewater treatment plant when the sewer network is flat and catchment area is big.
Reliability of sewer flow quality models - results of a North Rhine-Westphalian comparison
Authors: Russ H.-J.
Published: May 2018

In North Rhine-Westphalia, Germany a project for the evaluation of sewer flow quantity and quality models was carried out with the aid of measured data in 1986 to 1991. Measurement projects in two real subcatchments in the cities of Solingen and Düsseldorf delivered the data for model calibration and verification. 10 models with different approaches for quantity and quality simulation took part in a relative and an absolute comparison. This report focuses on some selected results of the absolute comparison and discusses the reliability and accuracy of model application.
Unsteady flow sediment transport in a sewer model
Authors: De Sutter R. , Huygens M. , Verhoeven R.
Published: May 2018

To initiate a fundamental understanding of the complex nature of unsteady sediment transport phenomena, laboratory experiments for two types of non-cohesive material are presented. These experiments were performed in a test flume with semi-circular cross-section. Friction velocity for the transient regime is obtained using the equations of de Saint-Venant, which are rearranged using the kinematic flow principle. Inertia of bed load material and material in suspension causes a time and forme discrepancy between the unsteady friction velocity and transport. Hence the friction velocity obtained with a steady state formula is chosen as basic parameter to setup an instantaneous relationship with transport. A correction for the time lag is clearly a function of the unsteady character of the flow.
Removal of Humic Substances by UF and NF Membrane Systems
Authors: Bian Rulin , Watanabe Yoshimasa , Tambo Norihito , Ozawa Genzo
Published: May 2018

This paper deals with the removal efficiency and mechanisms of humic substances contained in a river water by ultrafiltration (UF) and nanofiltration (NF) membranes. UF membranes with molecular weight cut-off (MWCO) of 50 kDa to 200 kDa can remove only large molecular size humic substances (LMSHS). Even in the UF membranes operated under the cross-flow mode, the LMSHS were accumulated on the membrane surface, because the back transport velocity of LMSHS is always smaller than that of the permeate flux. Precoagulation enhanced the removal of humic substances effectively. The optimum coagulation conditions for removing the humic substances in the UF membranes was the same as that in the conventional coagulation/flocculation/sedimentation process. The vibration action increased the removal efficiency of humic substances in the NF membrane process. Strong shear produced by the vibration diffused away the humic substances from the membrane surface to the bulk water, therefore the accumulation of humic substances on/near the membrane surface, i.e. formation of cake and concentration polarization boundary layers, is prohibited.
Development of a Framework for Quantifying the Removal of Humic Substances by Biological Filtration
Authors: Huck P. M.
Published: May 2018

Biological filtration is finding increasing use in the treatment of drinking water and is one process that is used to remove humic substances. It would be extremely useful to have a framework to quantify such removals as a function of substrate and operating parameters. This paper explores the use of biofilter dimensionless contact time, X*, to provide such quantification. X* incorporates reactor contact time and surface area, as well as substrate diffusivity and biodegradation kinetic parameters. Removals of biodegradable organic matter increase with increasing X*, but in a less than proportional way. Investigations reported in the literature have shown very limited biodegradation of unozonated humic substances under water treatment conditions. Following ozonation much greater removals are reported. This can be attributed to the increase in diffusivity and biodegradability due to ozonation, which leads to a substantial increase in X* for a given filter
Pretreatment Effects on Activated Carbon Adsorption of Humic Substances: Distributed Fictive Component Analysis
Authors: Matsui Yoshihiko , Yuasa Akira , Li Fu-Sheng
Published: May 2018

Diluted solutions of a peat water and a biological wastewater effluent were subjected to coagulation, ozonation, and chlorination. The effects of these pretreatments on the removal of humic substances by activated carbon adsorption were tested. Batch adsorption isotherms were analyzed using a distributed fictive component method, which assumed a logarithmic normal distribution of Freundlich K and a non-adsorbable fraction in the Ideal Adsorption Solution Theory for multicomponent adsorption. Coagulation treatment not only increased adsorbabilities but also decreased its heterogeneity in terms of multicomponent adsorbates. Ozonation decreased adsorbabilities and increased heterogeneity in adsorbabilities by producing weakly adsorbing compounds. The average Freundlich K decreased, while the Freundlich exponent, 1/n, and non-adsorbable fraction was increased with ozone consumption. Chlorination showed the same effects as ozonation. However, after ozonation, equilibrium capacity at low activated carbon doses was increased because of the reduced dissolved organic carbon concentration by ozonation.
GIS supported evaluation of source control applicability in urban areas
Authors: Makropoulos C. , Butler D. , Maksimoviċ Ĉ.
Published: May 2018

Although considerable effort is being expended to quantify the phenomena involved in source control and to produce guidelines for its application, there is still a lack of reliable, site-specific implementation methodologies. This study, using the multi-parameter handling capabilities of a geographical information system (IDRISI - GIS), aims to provide a methodological approach to source control implementation, taking into account both theoretical concepts and spatial characteristics of the implementation site. This is achieved by the creation of suitability maps for source control implementation using IDRISI-GIS and semi-hypothetical data from a case study catchment (Klisa in Novi-Sad, Yugoslavia). The existing drainage system and the receiving canals were introduced in the GIS, together with a digital terrain model, land use information and information on soil characteristics, connectivity to the system, and groundwater levels. Suitability maps were produced based on a theoretical criteria set created for the purposes of this research. The results indicate that GIS has a significant potential as a tool for site specific source control implementation, analysis and quantification, not only due to its inherent spatial information handling capabilities, but also due to its “human readability”..
The Danube Accident Emergency Warning System
Authors: Pintér György G.
Published: May 2018

Significant number of accidental water pollution incidents occurred during the past decades in the Danube River Basin, often having transboundary impacts. Growing needs arose at the important water users (first of all at drinking water intakes) along the rivers to get early warning about such incidents. The Danube Accident Emergency Warning System (DAEWS) was put into operation in April 1997, as a result of the short term priority action of the Environmental Programme for the Danube River Basin. The Danube Accident Emergency Warning System provides immediate information on sudden changes in water characteristics, like accidental river pollution incidents having transboundary effects, to assist the responsible authorities and water users in the downstream countries to make preventive measures in time. The countries where the system is now operational are (in the order of their location in the river basin): Germany, Austria, Czech Republic, Slovakia, Hungary, Slovenia, Croatia, Romania, and Bulgaria. The National Centres of the system established within the programme in each of the co-operating countries are called as PIACs (Principal International Alert Centres), being in close contact with the national pollution control structures. To meet the requirements on fast information transmission capabilities, the system are equipped with a satellite communication system linked to local computer network between the units of the PIACs with information processing system, hazardous substances database, the Danube Basin Alarm Model for the simulation of pollution effects. International Operation Manual provides the standard operation technique in each country. Practical example of the serious chemical accidental spill in Hungary in May 1998 illustrates the operation of the DAEWS system.
Modelling Phytoplankton in the Vaal River (South Africa)
Authors: Cloot A. H. J. , Pieterse A. J. H.
Published: May 2018

In this study a site-specific, multi-algal species mathematical model is developed to allow meaningful predictions of water quality of the Vaal River on a short and medium time-scale. The model takes into account the variability of six environmental variables, namely light, temperature, turbidity, dissolved inorganic nitrogen, phosphorus and silicon concentrations, that are all known to have a major effect on algal growth in the river.
Balancing Stream and Wetland Preservation with Nonpoint Source Pollution Management: A Case Study
Authors: Der Andrew T.
Published: May 2018

The regulation of development-related activities can require complex approaches to the management of nonpoint source pollution (NPSP) associated with such activities. Experience has shown that growth and transportation needs can be accommodated in a manner which avoids and minimizes stream and wetland impacts while remaining compatible with effective NPSP management strategies, herein referred to as stormwater management (SWM). The Maryland Department of the Environment (MDE) has developed a “one stop shop” review and assessment procedure where applicable federal and State regulatory programs are combined into a single process where on-site conditions are assessed, potential impacts are identified and mitigative practices are proposed sufficient to offset habitat loss and comply with water quality standards. The example presented is the first of several development projects in a 405 hectare (1000 acre) watershed of the Potomac River in the greater Washington, DC area of Maryland. The project, submitted in 1989, proposed stream and wetland impacts for road construction and runoff catchment basins which were determined by MDE to be avoidable. Impacts were reduced and mitigated by design revisions and innovative approaches to wetland re-creation and SWM. Subsequent development projects in this watershed are currently expanding in a manner which utilizes and refines data obtained from this initial project with completion expected by 2003.
Management Strategies for the Lower Seyhan Catchment
Authors: Onur Aylin K. , Ekemen Elif , Soyupak Selçuk , Yurteri Coşkun
Published: May 2018

The Seyhan river has a total catchment area of 20,731 km2 with major pollution sources located downstream of the Seyhan Dam in Adana. The so-called Lower Seyhan, is under the threat of not only domestic and industrial wastewater discharges originating from the metropolitan area of Adana, but also agricultural wastes of the fertile Çukurova Plain. In this study, the present and future water quality characteristics of the Lower Seyhan have been investigated by means of a mathematical modelling study based on actual field data as well as in-situ water quality measurements. The model of choice was the QUAL2EU. The behaviour of the Lower Seyhan was studied under different pollution control scenarios in order to develop plausible water quality management strategies for the target year of 2010. As a result of these studies, two alternative systems were proposed for the management of the wastewater sources within the Lower Seyhan catchment. Alternative wastewater treatment plant designs and their cost implications were evaluated by means of the CAPDET-PC software package. A user-charging scheme and an optimisation model that can be used for demonstrating the economic viability of the proposed systems were also developed for obtaining a cost-optimum management policy for both municipalities and industrial establishments of the area.
Dissolved and particle-bound substances in urban snow
Authors: Viklander Maria
Published: May 2018

In order to create a picture of the pollutant pathways for snow in urban areas, snow samples were collected in the city of Luleå, northern Sweden. Sampling sites were chosen in the city centre and in a housing area - three different sites in each area. Snow samples were collected during the whole winter of 1995. The results showed that the amounts of dissolved substances as percentages of the total amounts varied according to time, site and the type of substance. For the sites along the roadsides in the city centre, the amounts that were in solution were less than 1% of the lead, 2.5% of the phosphorus, 11% of the copper, and 18% of the zinc. For the site with no-traffic, the dissolved fractions were considerably higher.