bluuebunny/crossref_metadata_2025 huggingface dataset:
Biological assaying of organic compounds in surface waters
Authors: Guzzella L. , Mingazzini M.
Published: May 2018

A biological monitoring program (1992-93) was undertaken with the aim of testing the toxic effect of the Lambro, one of the most polluted rivers in Northern Italy. The filtered river samples were tested with S. capricornutum in a 96h exposure growth inhibition assay and with a photobacterial inhibition assay with the LUMISTox System. The unfiltered samples were also tested with LUMISTox, in order to evaluate the role played by the suspended and colloidal material in the water toxicity. The river samples were passed through a series of columns filled with Carbopack B, XAD-2 and C-18 respectively to concentrate organic compound for chemical analysis and enriched with EDTA to complex metals. The Carbopack B procedure proved to be the most efficient among the tested extraction techniques. The de-toxificant effect of the sample treatments was evaluated in terms of percentage increase of the cell density by the algal assay, while the toxicity of the extracted organic compounds was evaluated by LUMISTox System. The comparison of algal assay with chemical analysis results pointed out that the toxicity of the Lambro waters was mainly related to pesticide contamination.
Nonextractive immunoassay analysis of contaminated sediments
Authors: Mossman D. J. , Baker C. J. , Feldbush T. L. , Lappin S. A.
Published: May 2018

A novel testing method determines the amount of organic compounds sorbed to sediments. It is a nonextractive immunoassay which has demonstration data for 2,4-dinitrobenzene sulfonate (a model pollutant for which antibodies are commercially available) sorbed to crushed brick (a model sediment surrogate). the nonextractive immunoassay quantitatively distinguishes between contamination levels. Advantages of the nonextractive immunoassay include small sample size (<1 g), easy adaptation to field testing, and elimination of extraction solvents.
Detection of heavy metal toxicity and genotoxicity in wastewaters by microbial assay
Authors: Codina J. C. , Pérez-García A. , de Vicente A.
Published: May 2018

The effect of wastewater on the sensitivity of toxicity and genotoxicity assays for the detection of heavy metals was evaluated. Five microbiological toxicity tests were used to compare the toxicity of cadmium, copper, chromium, mercury, nickel, and zinc, both in deionized water solutions and in wastewater. The toxicity assays employed were: Microtox®, two tests of growth inhibition using Pseudomonas fluorescens, and two spectrophotometric assays of the inhibition of respiration test using baker's yeast and P. fluorescens. Also, the genotoxic effect of the assayed metals was evaluated by using the Ames test, the Escherichia coli WP2 test, and the SOS test. The sensitivity to metals decreases in most of the toxicity and genotoxicity assays; in general, higher sensitivity thresholds (EC20) in wastewater than in water solutions were determined. Each test shows different sensitivities to each metal, which is related to different sensitivities of the organisms used in the assays, as well as to other factors.
Estimation of maximum specific growth rate of heterotrophic and autotrophic biomass: a combined technique of mathematical modelling and batch cultivations
Authors: Novák Libor , Larrea Luis , Wanner Jiri
Published: May 2018

Present methods for determination of kinetic and stoichiometric parameters are mostly based on simple and rapid batch cultivation. An alternative technique of mathematical simulation and a batch cultivation was proposed for estimation of maximum specific growth rates of heterotrophic and autotrophic microorganisms in activated sludge. Estimation of heterotrophic and autotrophic fractions in the biomass is based on mathematical model calibration of continuously operated system. Maximum growth rates are then calculated from the maximum OUR measured in batch tests. The proposed method was compared with a batch test cultivation based on an exponential growth of microorganisms when a proportion of filtered wastewater is mixed together with a small proportion of biomass and aerated in time. Comparing both methods, a disproportion between obtained results was found (μH,max = 4 d−1 from the proposed, and μH,max = 10 d−1 from the batch test method). An explanation of this observation was based on a hypothesis that under batch test conditions (higher S0/X0 ratio) faster-growing microorganisms can be favoured in their growth. This phenomenon was mathematically simulated with a simplified model and confirmed. Therefore, it is recommended that some constants for mathematical modelling obtained from batch tests should be applied on continuously operated systems only with care.
Evaluation of the rate of hydrolysis of slowly biodegradable COD (SBCOD) using starch as substrate under anaerobic, anoxic and aerobic conditions
Authors: San Pedro Delfin C. , Mino Takashi , Matsuo Tomonori
Published: May 2018

In the Activated Sludge Model No. 1 proposed by an IAWPRC Task Group, the possible differences of the hydrolysis rate for the slowly biodegradable organic compounds (SBCOD) under aerobic, anoxic and anaerobic conditions are accounted for by the introduction of a correction factor ηh. In the present study, this factor ηh was experimentally evaluated using starch as organic substrate to represent SBCOD. It was found that after the activated sludge had been well acclimatized with starch, the hydrolysis rate is insignificantly affected by the condition of the final electron acceptor. The value of ηh approaches unity. Results also suggested that biomass concentration has no significant influence on hydrolysis rate of starch.
Acinetobacter cell biomass, growth stage and phosphorus uptake from activated sludge mixed liquor
Authors: Cloete T. E. , Bosch M.
Published: May 2018

Enhanced biological phosphorus removal activated sludge plants often do not remove phosphorus adequately in order to meet legal demands.

Currently FeSO4 is being added to almost all South African nutrient removal activated sludge systems discharging effluents to the sensitive catchments to prevent phosphorus from entering fresh water systems. In order to understand biological phosphorus removal mechanisms in order to optimise the process, the role of growth rate and phosphorus removal in Acinectobacter was investigated.

Phosphorus was accumulated in the lag phase of the normal growth cycle. Little or no phosphorus was accumulated in the logarithmic growth phase, instead phosphorus was released at the beginning of logarithmic growth. Further phosphorus accumulation took place in the stationary phase, once active growth had ceased.

Cells had a limit to the amount of phosphorus that could be accumulated per cell irrespective of substrate availability. It was therefore concluded, that the number of cells (biomass) in a system and their growth stage were crucial factors governing biological phosphorus removal. Maximum cell numbers should therefore be obtained and logarithmic growth should be prevented in the aerobic zone, in order to optimize biological phosphorus removal from activated sludge.
An improved small sewage treatment plant for biological purification of wastewater
Authors: Voigtländer G. , Kulle E.-P.
Published: May 2018

The paper presents a small sewage treatment plant (package plant) operating without additional energy. Purification of sewage is achieved in a three-step process: sedimentation tank, anaerobic reactor and wastewater pond or aerobic reactor. The efficiency of the anaerobic reactor - in contrast to the efficiency of a common septic tank - is significantly increased by using fixed biomass systems. Further degradation of sewage compounds by adhering microorganisms occurs in pond or aerobic reactor. The bed for the aerobic biomass is made of a semipermeable plastic film and arranged in order to ensure simultaneous supply of oxygen. The three pilot plants are showing different results. The main aims of research i.e. lowering of operational costs, energy supply, minimizing of maintenance expenditure and cleaning work, reliability of degradation efficiency have been achieved so far for the anaerobic reactor.
Acidogenic microbial species diversity in anaerobic digesters treating different substrates
Authors: Britz T. J. , Spangenberg G. , Venter C. A.
Published: May 2018

Microbial species diversity was determined for the acidogenic populations of four different digesters treating landfill leachate, a petrochemical effluent and sewage. The digesters were a downflow fixed-bed, conventional, cold conventional and an upflow hybrid design. The 288 strains isolated from the digesters were characterized using API test systems and identifications confirmed using current taxonomic methods. The taxonomic diversity was determined using the Shannon (H′) and equitability (J′) indices. The species from the four digesters were very similar with the exception of those from the digester treating the landfill leachate. The higher diversity in the latter was probably due to the diverse composition of the leachate, suggesting that members of this population were more generalists, as opposed to the more narrowly constrained members in the other three digesters. The data indicated that in a digester environment dominated by a more specific carbon containing effluent, like a petrochemical effluent, the population becomes stenotolerant and is characterized by a lower species diversity. Such a population would not be able to cope as well with environmental fluctuations. With a more diverse substrate like the landfill leachate, generalists, having a wider range for environmental variables, would dominate. This is important in terms of anaerobic digester process efficiency and stability.
Microbial structure and activity of UASB granules treating different wastewaters
Authors: Fang H. H. P. , Chui H. K. , Li Y. Y.
Published: May 2018

The microstructure of three types of UASB granules respectively treating sucrose, glutamate and brewery wastewaters in mesophilic conditions were analyzed by light, scanning electron and transmission electron microscopies, along with the specific methanogenic activity (SMA) of the granules. Results showed that the granule's microstructure was dependent on the nature of the substrate. Those degrading soluble carbohydrates exhibited a layered structure, while those degrading glutamate exhibited a rather uniform structure. Such a difference was explained based on the substrate's rates of acidogenesis and diffusion. A model of the typical layered structure was proposed. In addition, the acetoclastic Methanothrix was found as the key structural element in all the granules, suggesting that it plays an important role in granulation. Three types of syntrophic microcolonies were found to be abundant in granules degrading soluble carbohydrates: two were juxtapositioned syntrophic microcolonies, each was composed of hydrogen-producing acetogens and hydrogen-consuming methanogens, while the third was a cluster-type of syntrophic association between two microcolonies. The SMA data using individual VFA as substrate provided supporting evidence to the observations of the bacterial compositions in the granules.
Modelling struvite precipitation in anaerobic treatment systems
Authors: Loewenthal R. E. , Kornmüller U. R. C. , van Heerden E. P.
Published: May 2018

Struvite precipitation is common in waste water systems containing high concentrations of dissolved orthophosphates, free and saline ammonia and magnesium ions, such as in anaerobic fermentation systems, often leading to severe fouling. It appears that a reduction of the partial pressure of CO2, ie. pCO2 is a trigger mechanism for struvite precipitation. An algorithm was developed, based on equilibrium chemistry, to quantitatively predict the struvite precipitation potential of the water in such a process. This was then extended, to predict the change in state together with precipitation potential due to chemical perturbations, particularly variations of pCO2. Experimental verification of the algorithms is presented.
Design and operation of landfills for optimum stabilization and biogas production
Authors: Pohland F. G. , Al-Yousfi B.
Published: May 2018

Most municipal landfills are constructed and operated with exposure to intermittent rainfall. Infiltration of rainfall, together with the inherent moisture content of landfilled wastes, promotes leachate production and accelerates rates of conversion of waste constituents. As these conversion processes proceed, waste stabilization occurs, leachate quality changes, and biogas is released in correspondence with the prevailing phase of stabilization. The intensities and temporal and spatial dimensions of these phases are waste-specific, a function of landfill design and operational strategy employed, and characterized by changes in physical, chemical and biological indicator parameters.

Recognizing that most landfills exist as microbially mediated anaerobic waste conversion processes, with the sequential phases of acid formation and methane fermentation accounting for the majority of waste stabilization being accomplished, a fundamental understanding of these two principal phases of landfill stabilization is provided and used as a basis for developing guidance for controlled landfill design and operation. This guidance emphasizes optimization of stabilization efficiency, establishes cost-effective procedures for leachate management, and promotes regulated biogas production and utilization.

To accommodate these objectives, the benefits of converting landfills into controlled bioreactor systems through regulated leachate generation, containment, collection, and in situ recirculation for accelerated waste stabilization and integrated biogas management are described, and opportunities for ultimate leachate disposal, biogas utilization and landfill reclamation are illustrated and compared to relative costs of other management options.
Field experience with different systems for biomass accumulation in anaerobic reactor technology
Authors: Defour D. , Derycke D. , Liessens J. , Pipyn P.
Published: May 2018

Thanks to undeniable advantages as recovery of energy and a low sludge production, anaerobic wastewater treatment has received recognition in the last decade. However due to the slow methanogenic growth, inreactor biomass accumulation is essential to maintain high loading rates. Indeed wash-out of biomass is one of the main problems encountered in the anaerobic treatment of industrial effluents. A broad scoped overview of the different reactor technologies is given each with its proper biomass accumulation system. All of them are founded on two basic mechanisms for biomass accumulation: separation and retention. Settling (Anaerobic Contact reactor), ultrafiltration and flotation (FlotametP) are the techniques used to separate externally the biomass from the effluent after which the biomass can be recirculated to the anaerobic reactor. Concentration of biomass can also be achieved by attachment to a mobile (Fluidized Bed reactor) or a static carrier with possible entrapment in its macroporous structure (Anaerobic Filter reactor). The UASB-reactor incorporates retention as well as separation. By stimulating granular growth, biomass is accumulated in the lower part of the reactor. A three phase separator at the top of the reactor contributes to the final clarification of the effluent. Hybrid reactors eventually combine different biomass accumulation mechanisms: granulation, external biomass separation (Upflow Anaerobic Contact reactor) and fixation (Upflow Anaerobic Contact Filter reactor).
Upgrading to nitrogen removal with the kmt moving bed biofilm process
Authors: Rusten Bjørn , Siljudalen Jon G. , Nordeidet Bjørnar
Published: May 2018

A new moving bed biofilm reactor (MBBR) has been developed in Norway. The biomass is attached to carrier elements that move freely along with the water in the reactor. It has been demonstrated that existing, high loaded, activated sludge plants can easily be upgraded to nitrogen removing MBBR plants. With chemically enhanced mechanical treatment, full scale tests showed that 80-90% total nitrogen could be removed in a MBBR plant at a total empty bed hydraulic retention time (HRT) of 2.6 hours. The plant was operated in the post-denitrification mode, using methanol as an external carbon source.
Size distribution model for methanogenic granules from full scale UASB and IC reactors
Authors: Pereboom J. H. F.
Published: May 2018

The size distribution of methanogenic granules from ten full scale UASB and Internal Circulation (IC) reactors were studied at regular time intervals. A size distribution model was developed based on these data and additional lab-scale experiments. Full scale data were used, since the hydrodynamic conditions in full scale reactors influencing the size distribution cannot be simulated properly in lab scale reactors. It was concluded that breaking and/or disintegration did not significantly contribute to the size distribution. Washout of granules is under normal conditions negligible, since the settling velocity is much higher than the liquid upflow velocity. Gradient measurements showed that the sludge bed is well mixed. Thus, sluicing will not systematically remove large granules. The most significant process limiting the maximum granule size in normal operation is the regular sluicing of surplus biomass. Shear forces appear to have no influence on the size distribution. High numbers of precursors in the influent result in short size distributions, while in wastewaters with little or no suspended solids wide size distributions can be found. The developed size distribution model accurately described the wider size distributions found in IC-reactors. IC-granules are larger and less strong as compared to UASB granules. Furthermore, it was concluded that operating the systems at high loadings results in granules with a lower strength. The density of methanogenic granules is strongly correlated with the ash content.
Improving the performance of anaerobic digesters at wastewater treatment works: the coupled cross-flow microfiltration/digester process
Authors: Pillay V. L. , Townsend B. , Buckley C. A.
Published: May 2018

Trials at a wastewater treatment works indicate that cross-flow microfiltration, using flexible woven fibre tubes, could significantly enhance the performance of anaerobic digesters. The cross-flow microfiltration unit decouples the solids residence time from the liquid residence time and thus enables the volumetric throughput of the digester to be significantly increased while maintaining a constant solids residence time and volatile solids destruction. In trials on a pilot-plant digester, the volumetric throughput was almost doubled, from 70 to 130 1 d−1, while the solids residence time was maintained at 26 days. The economic feasibility of the coupled system was evaluated, using permeate flux data obtained from a cross-flow microfiltration unit coupled to a full-scale digester. The evaluation indicates that the coupled process is economically favourable when compared to conventional digester systems. The coupled system is currently being developed into a full-scale process. A full-scale CFMF unit is being constructed and will be coupled to a full-scale digester. Over a three year project the long-term reliability and operability of the process will be investigated, together with its effect on digester fluid dynamics and biomass viability.
Optimization modelling of anaerobic biofilm reactors
Authors: Suidan Makram T. , Flora Joseph R. V. , Biswas Pratim , Sayles Gregory D.
Published: May 2018

A rigorous steady state model of acetate-utilizing methanogenic biofilms is developed accounting for the mass transfer of neutral and ionic species, pH changes within the biofilm, pH-dependent Monod kinetics, chemical equilibrium, electroneutrality, gas production within the biofilm, and the presence of a concentration boundary layer (CBL). In contrast to traditional biofilm models where the pH is assumed to be constant within the biofilm, an increase in pH in acetate-utilizing methanogenic biofilms is predicted. Furthermore, significant differences can exist between the flux predictions using the traditional models and when pH changes within the biofilm are taken into account. The optimum pH for acetate-utilizing biofilms is less than the optimum defined for suspended-growth systems. The biofilm model is coupled to a model of a completely-stirred tank reactor (CSTR), and strategies for the optimization of biofilm reactor performance are examined. For a fixed set of operating conditions, an optimum influent pH can be defined that corresponds to the maximum removal efficiency and flux of acetate into the biofilm.
Anaerobic purification of brewery wastewater in biofilm reactors with and without a methanation cascade
Authors: Stadlbauer E. A. , Oey L. N. , Weber B. , Jansen K. , Weidle R. , Löhr H. , Ohme W. , Döll G.
Published: May 2018

A laboratory scale anaerobic treatment process for brewery wastewater has been investigated. It utilised a continuously stirred tank (CST) acidification reactor (11.3 1) plus an anaerobic treatment system which consisted of either a downflow stationary fixed film (DSFF) reactor (20.7 1) or a DSFF reactor in series with a floc (FLOC) or sludge blanket reactor (20.8 1). At the same residence time the combination of DSFF and FLOC reactor performed better than a single methane digester. Using low and high strength wastewater, degradation yields of 80-90% were obtained at total loading rates BR,COD up to 10 kg COD m−3 × d and a residence time t less than one day. Mean values of methane yield were 0.31 m3STP kg-1 COD or 2.91 m3STP m−3 × d. Inert support media investigated consisted of inorganic materials such as porous Kerapor 1000 and glass sponge (Siran) with macro- and micropores or polyurethane foam (Filtren TR 30) with an open net structure. In all cases SEM showed appropriate surface characteristics for microbial attachment. After 4 months of operation biofilm thickness on inorganic support media was 0.4-0.9 mm at a superficial linear velocity (SLV) of 10-5 mm min−1. Under these conditions biofilm on Filtren TR 30 was noticeably thicker (up to 2 mm). Concerning metal contamination of biofilm on Filtren TR 30, Al, Fe and Zn showed elevated levels above 2000 ppm.
Urban Drainage: Review of Contemporary Approaches
Authors: Maršálek J. , Sztruhár D.
Published: May 2018

Recent developments in urban storm drainage are reviewed starting with rainfall/runoff processes, followed by discussions of combined sewage, drainage impacts on receiving waters, impact mitigation, hydroinformatics, regulatory programs and conclusions. The most promising trends in this field include improvements in spatial definition of rainfall data, runoff modelling with a limited number of model parameters and recognition of modelling uncertainties, analytical statistical modelling of runoff quality, advances in the understanding and modelling of sewer sediment transport, the use of biomonitoring and modelling in assessing drainage impacts on receiving waters, further refinement of best management practices for stormwater management, development of new processes for treatment of stormwater, experience with vortex combined sewer overflow structures and their applications in combination with other treatment devices, real time control of sewer system operation, advances in hydroinformatics leading to improvements in the integrated management and modelling of drainage systems, interfacing of drainage models with geographic information systems, and improved regulation of drainage effluents.
Analysis of the Rain Phenomenon at Fine Spatial Scale
Authors: Paturel J. E. , Chocat B.
Published: May 2018

Since 1984, the Urban Community of Lyon (CO.UR.LY.) has been setting up a network of rain gauges with a density of about 1 station per 20 km. This network is integrated in the French system of Experimental and Representative Basins. To get a better knowledge of the spatial distribution of the rainfall, a study was based on the establishment of I.D.F. relationships for each of these measuring stations. Since the study period extended only over 5 to 6 years, only return periods of 1 and 2 years were taken into account. The results show a high statistical heterogeneity of rain gauging data. These discrepancies may be due to sampling errors, to systematic measuring errors, to an excessively short observation period or to real spatial differences in rainfall. Each one of the causes of error was studied, and these 4 points all seem to play a more or less significant role in the differences observed between the stations. Thus there may be a spatial heterogeneity of the rainfall over the area of the CO.UR.LY. If confirmed, this observation may have very important consequences and may question risk assessment in urban hydrology.
Is Hydraulics Over-Used or Under-Used in Storm Drainage?
Authors: Chie Yen Ben
Published: May 2018

Urban drainage models utilize hydraulics of different levels. Developing or selecting a model appropriate to a particular project is not an easy task. Not knowing the hydraulic principles and numerical techniques used in an existing model, users often misuse and abuse the model. Hydraulically, the use of the Saint-Venant equations is not always necessary. In many cases the kinematic wave equation is inadequate because of the backwater effect, whereas in designing sewers, often Manning's formula is adequate. The flow travel time provides a guide in selecting the computational time step At, which in turn, together with flow unsteadiness, helps in the selection of steady or unsteady flow routing. Often the noninertia model is the appropriate model for unsteady flow routing, whereas delivery curves are very useful for stepwise steady nonuniform flow routing and for determination of channel capacity.
Chemodynamics of Trace Pollutants during Roof and Street Runoff
Authors: Herrmann Reimer , Daub Joachim , Förster Jürgen , Striebel Thomas
Published: May 2018

The fate of ionic and non-ionic organic compounds and trace metals during roof and street runoff is sensitive to their distribution between sorption onto roof and street material and suspended solids on one hand and the dissolved phase on the other hand. Using field data of runoff, suspended solids concentration and the chemical state of various trace pollutants, we try to explain the factors governing the chemodynamics and the transport behaviour during roof and street runoff.
Fluid Sediment in Combined Sewers
Authors: Ashley R. M. , Arthur S. , Coghlan B. P. , McGregor I.
Published: May 2018

The importance of solids in sewer systems as a primary source of pollutants is widely acknowledged. The re-suspension of bed deposits and bed-load material in accelerating flows is believed to be the primary source of foul flushes of pollutants. As yet only inferential data are available linking bed deposits to foul flushes of suspended pollutants.

Studies are described which have investigated the movement of material transported near the bed in combined sewers. The similarities with bed-load and fluid mud in river and estuarine flows are examined and the relationship between this material and foul flushes is considered.
Parameter Uncertainty Propagation Analysis for Urban Rainfall Runoff Modelling
Authors: Lei Jianhua , Schilling Wolfgang
Published: May 2018

The paper proposes a strategy for model uncertainty propagation analysis. As an example, parameter uncertainty propagation analysis in the runoff block of the HYSTEM-EXTRAN model is carried out. The model is a modification of the well-known SWMM (Storm Water Management Model). Uncertainty propagation methods such as first-order analysis, sensitivity analysis, statistical linearization and Monte-Carlo analysis are discussed and applied. A pathway of parameter uncertainty propagation analysis is given based on validity, simplicity, and computational requirements. The pathway starts with sensitivity analysis which may help to reduce the dimensions of a multidimensional model by discarding insensitive parameters. This is to obtain a mathematically tractable uncertainty propagation problem for a complicated model. Then, the nonlinearity of the model must be quantified to check the validity of first-order analysis. If first-order analysis is not valid, and if components of model output uncertainty need to be known, the application of statistical linearization is the only analytical alternative. Monte-carlo analysis can always be applied and taken as a reference as long as the components of the model output uncertainty are not of interest. The parameter sensitivity is characterized by its sensitivity coefficient which is defined as the ratio of the coefficient of variance of a model output to the coefficient of variance of the model parameter itself. A nonlinear rainfall runoff model usually results in a variable parameter sensitivity. Hence, recommendations about parameter sensitivity cannot be generalized for a given rainfall-runoff model, but depend on the type and the range of the model output variable. It is shown that the type of probability density function describing the parameter uncertainty with known mean and variance has only a small effect on the results of the model output uncertainty.
Rainfall-Runoff Modelling of Partly Urbanized Watersheds: Comparison Between a Distributed Model Using GIS and Other Models Sensitivity Analysis
Authors: Zech Y. , Sillen X. , Debources C. , Van Hauwaert A.
Published: May 2018

This paper presents an original integrated approach to rainfall-runoff modelling for partly urbanized watersheds. A digital terrain model (DTM), allowing use of GIS techniques, was built not only for representing the undeveloped part of the catchment but also the urbanized area. For each cell of the DTM grid, a water budget is computed, providing runoff and interflow amounts. The water volumes generated at each cell are moved along the steepest slopes with a celerity depending on this slope, until they reach the outlet and contribute to the resulting hydrograph.

The model was tested in a partly urbanized catchment, specially equipped with rain and flow measurement station. Comparisons with other procedures, mainly with SWMM and WALLRUS models, shows that the proposed model seems to be one of the most accurate. Moreover, the sensitivity analysis confirms the flexibility of the tool. Its concept, based on GIS routines, allows much of the computation to be done automatically, avoiding a lot of tedious tasks. For example, it becomes relatively easy to check the consequences of urban planning options.
Urban Stormwater Infiltration Perspectives
Authors: Geldof Govert , Jacobsen Per , Fujita Shoichi
Published: May 2018

In urban areas there are many problems with water management: combined sewer overflows, peak flows, man-induced droughts, consolidation of the soil, damage from frost penetration, etc. It is preferable to look at all these problems in relation to each other, according the concept of integrated water management. This paper focuses on the possibilities for urban stormwater infiltration.

The results of three studies are presented. The first study concerns the flooding of the Shirako River in Tokyo. It is shown that with the help of stormwater infiltration the floods can be reduced remarkably. The second study concerns combined sewer overflows and the discharge from treatment plants for catchments in Denmark and the Netherlands. When looking at the total yearly discharge from the combined sewer and the treatment plant, it is shown that infiltration is more effective than detention. The third study shows the impact of urban stormwater infiltration on the ground water flux in an area in the south of the Netherlands.

To relate the different results from the three studies an analogy is introduced with the human body. The combination of problems results in a so-called urban hang-over. It is shown that the positive effects of urban stormwater infiltration within an integrated approach are more significant than looking at all the effects separately.
Performance of the Drainage Infiltration Strata: Statistical and Numerical Analyses
Authors: Harada Shigeki , Ichikawa Arata
Published: May 2018

The Drainage Infiltration Strata is an artificially devised soil structure comprised of artificial turf, permeable pavement, a layer of gravel, a layer of sand and a drainage pipe with a watertight sheet. When impermeable pavement on grounds or in other public spaces is replaced with the drainage infiltration strata, the volume and the rate of stormwater runoff is reduced. This is due to the fact that the water on the surface of the drainage infiltration strata passes into the layer of gravel and is retained. The drainage pipe with the watertight sheet at the bottom of the strata removes water retained within the layer of gravel. This causes runoff from the strata, but the capacity within the layer of gravel is maintained. Data on a full scale model experiment at the baseball field of the University of Tokyo showed thatthe average volume of runoff for sixty rainfalls was reduced to 42% of that of rainfall;the average rate of peak runoff for 12 especially heavy rainfalls was reduced to 22.3% of that of peak rainfall.

A numerical model to reproduce the behaviour of stormwater within the strata was formulated using the two-dimensional Richard's equation. With this model, the effect of the drainage infiltration strata on reducing the volume and rate of stormwater surface runoff, during a design storm, was predicted.
Comprehensive Stormwater Pond Monitoring
Authors: Edgar Watt W. , Maršálek Jiri
Published: May 2018

Stormwater management ponds are widely used to control urban stormwater pollution. An understanding of the relevant biological, chemical and physical processes in such ponds requires a comprehensive monitoring program. Such a program is described for a 0.52 ha pond near Kingston, Ontario. In addition to continuous measurement and discrete sampling of pond inflow, storage and outflow to define the overall mass balances of water, sediment and chemicals, the program includes special process-related surveys and investigations. These include analyses of bottom sediment cores, suspended sediment and submergent plants as well as modelling/measurement of the velocity field and sediment transport. This comprehensive monitoring program is presented as an example of what should be implemented in many climatic regions before transfer of data on pond performance can be justified.
Assessment of Stormwater BMPs and their Technology
Authors: Urbonas Ben
Published: May 2018

The use of separate stormwater Best Management Practices (BMPs) has become common in United States, Europe, Australia and other parts of the world. Much of this technology is emerging and, as a result, it is sometimes used without fully understanding its limitations and without recognizing its effectiveness under field conditions. This paper presents and evaluates a number of structural and non-structural BMPs. The evaluations are based on extensive literature review, field observation and discussions with stormwater professionals in many parts of United States about their experience with BMP performance.
Municipal Wastewater Systems, Integrated Approach to Design, Monitoring and Control
Authors: Harremoës P. , Hvitved-Jacobsen T. , Lynggaard-Jensen A. , Nielsen B.
Published: May 2018

A city and several companies joined in a large scale project with the aim to introduce real time control of the sewer system and the wastewater treatment plant. The basic goals were established from the receiving water studies, and essentially represent constraints on the total nutrient discharge causing eutrophication of a fjord and limits on oxygen depletion by combined sewer overflows in the small upstream rivers. The paper describes the basic principles and approaches for the real time control in urban wastewater systems.
Techniques for Closing the Water Circuits in the Pulp and Paper Industry
Authors: Edde Howard
Published: May 2018

The focus of this paper is on the earlier, recent and future developments in closing the water circuits in pulp and paper production. During the 1960s the U.S. pulp and paper industry was in its environmental infancy concentrating mainly on removal of settleable solids and initiating river assimilative capacity studies. The 1970s began with environmental legislation having enforceable powers to achieve primary and secondary (biological) treatment which was fundamentally fulfilled during the 1980s. The late 1980s and early 1990s opened with toxicity becoming the major environmental issue as measured mainly by absorbable organic halogens (AOX) and dioxins. This paper identifies progress and key technological developments towards furthering stringent environmental enhancement and provides additional knowledge requirements leading into the next century.
Removal and Transformation of Resin Acids during Secondary Treatment at a New Zealand Bleached Kraft Pulp and Paper Mill
Authors: Zender J. A. , Stuthridge T. R. , Langdon A. G. , Wilkins A. L. , Mackie K. L. , McFarlane P. N.
Published: May 2018

Investigations were undertaken on a full scale lagoon treatment system receiving effluents from a bleached kraft pulp and paper mill which processed softwoods. The system was examined over four phases, including lagoons, aerobic transport channels and the recipient discharge point to determine the removal efficiency of resin acids during effluent treatment. The total treatment system removed 96% of the influent resin acids. The major compounds remaining after treatment were abietic acid, dehydroabietic acid, and a variety of hydrogenated resin acid transformation products. Each section of the treatment system differed in its ability to remove the major classes of resin acids. For example, the average removal rates for resin acids within the first phase lagoons and of the channel leaving the lagoons were 1.2 and 17 g.kg-1 VSS.day-1, respectively. A pathway for the biodegradation and biotransformation of influent resin acids is proposed on the basis of the observed changes in effluent composition through the treatment system.
Chlorinated Phenolics Removal from Bleached Kraft Mill Wastewater in Three Secondary Treatment Processes
Authors: Hall E. R. , Randle W. G.
Published: May 2018

Laboratory-scale activated sludge (AS), facultative stabilization basin (FSB) and aerated stabilization basin (ASB) processes were operated in parallel treating bleached kraft mill effluent under controlled SRT and temperature conditions, to assess the chlorinated phenolics removal efficiencies attainable in each. The structure and extent of chlorination of the chlorophenolic compounds monitored appeared to contribute to the differing removal efficiencies observed. Under most operating conditions, treatment process effluents contained chronically toxic levels of pentachlorophenol-equivalent toxicity (TEQ). A companson of the results obtained from the FSB, ASB and AS processes indicated that, under most operating conditions, chlorophenolics removal in low rate treatment systems is superior to that in a higher rate activated sludge treatment process. However, it was also observed that operation at long SRT and moderate temperature permitted enhanced removal of chlorophenolics and reduced TEQs to less than threshold values, in all three treatment processes.
Bioregeneration of Activated Carbon in a Fluidized GAC Bed Treating Bleached Kraft Mill Secondary Effluent
Authors: Vuoriranta P. , Remo S.
Published: May 2018

Secondary effluent from a bleached kraft mill activated sludge plant was treated in a pilot scale fluidized bed to remove residual organic carbon and AOX. Granular activated carbon was used as an adsorbent and support material for biomass. Physical adsorption and biodegradation were followed in a period of 18 weeks. Reduction of dissolved organic carbon was 57% throughout the period, mean load being 0.9 g of DOC/kg activated carbon in a day. AOX removal was more efficient, 70-90%. Reduction rate decreased in the course of time but could be partly recovered with addition of nutrients (P, N) to the nutrient deficient feed. A parallel experimental reactor was regenerated with ultrasonication/infrared - treatment. Physical regeneration gave a remarkable but temporary increase in the removal rate. A stable share of the total removal of DOC, 20-30%, was due to biodegradation and bioregeneration.
Post-Treatment of Pulp and Paper Industry Wastewaters Using Oxidation and Adsorption Processes
Authors: Kallas J. , Munter R.
Published: May 2018

The feasibility of using ozonation and adsorption for the post-treatment of biologically treated effluents of the pulp and paper industry has been studied. Equilibrium conditions, as well as the kinetics of both processes, have been determined. The COD, AOX (adsorbable organic halides) content and color were chosen as the main process parameters. General design of an ozone reactor and adsorption unit, as well as estimates of capital and operating costs for both processes, have also been presented. Some remarkable advantages of ozonation in comparison to PAC-adsorption have been emphasized: at the same purification cost ($/m3) ozonation can guarantee 7-8 times higher efficiency than adsorption. Destroying color bodies and toxic organochlorine compounds in the effluents from the pulp and paper industry with ozone has become very promising.
Control of Nutrient Discharges – Practical Experiences
Authors: Jansson Kaj , Järvinen Seppo , Koponen Raili , Temmes Armi
Published: May 2018

Metsä-Serla has studied the possibilities of controlling phosphorus and nitrogen discharges from its five activated sludge plants for several years in cooperation with various research programmes.

Phosphorus in waste waters has been found to originate mainly from wood, nitrogen mainly from process chemicals.

Efficient sludge separation is crucial for nutrient removal, but is usually not sufficient to meet the new stringent limits. The levels of soluble nutrients need to be lowered as well.

With few exceptions control of nitrogen discharges is dependent on the daily adjustment of nitrogen dosage to the activated sludge plant This is also the case for phosphorus control at paper mills. Efficient control of phosphorus discharges at pulp mills, on the contrary, can only be achieved by measures within the pulp production process.

Optimization of the nutrient dosages requires a rather large amount of analytical measurements of the purification process at the mill, which can be problematic especially for small production units.

The nutrient control strategies for pulp and paper mills, as well as the problems of secondary wastes produced by the purification processes are discussed.
Biofilters: flexible, reliable biological reactors
Authors: Pujol R. , Hamon M. , Kandel X. , Lemmel H.
Published: May 2018

More than fifty wastewater treatment plants worldwide (representing several millions p.e) are equipped with up-flow biofiltration reactors (BioforR). Their range of application encompasses municipal as well as industrial wastewater. A summary of the results achieved in a large number of plants is presented, accompanied by a description of the operating parameters and the treatment limitations with regard to various pollutants (C, N, P). The separation of functions into specific reactors combined with optimized wash conditions guarantees high treatment efficiency.
Dynamics of a nitrifying bacteria population in a biofilm controlled by an oxygen microelectrode
Authors: Horn H.
Published: May 2018

Population dynamics of nitrifying bacteria in an autotrophic biofilm were studied using an oxygen microelectrode. Nitrification and endogenous respiration were measured as function of oxygen concentration. Over a five weeks substrate - limiting period the shape of oxygen profiles in the biofilm had changed. The activity in the biofilm showed that the autotrophic fraction was displaced to the bulk/biofilm interface. After 5 weeks no more activity could be measured below 800 μm in the substrate-limited biofilm. Full ammonia load couldn't be buffered by those biofilms. After setting back the biofilm to full load, the profiles reached the original shape after 5 days. The results of microelectrode measurements were used to evaluate data for modelling population dynamics of nitrifying bacteria.
Carbon utilization in denitrifying biofilters
Authors: Jansen J. la Cour , Jepsen S.-E. , Laursen K. Dahlgren
Published: May 2018

Denitrification has been examined in pilot-scale upflow and downflow submerged filters. The filters have been operated on presettled wastewater, pre-precipitated wastewater, and nitrified effluent with external carbon source. The degradability of the incoming carbon is shown to be significant for the denitrification capacity of the wastewater. Soluble easy hydrolyzable organics are only partly degradedduring passage through the filters. Particulate organics trapped in the filter, however, contribute to the denitrification as part of the particles are hydrolyzed.
Combined nitrogen and phosphorus removal in a full-scale continuous up-flow sand filter
Authors: Hultman B. , Jönsson K. , Plaza E.
Published: May 2018

An attractive method for post-denitrification may be the use of sand filters. In this paper, a description and evaluation are given of full scale studies of the use of a continuous sand filter for the combined removal of suspended solids, phosphorus and nitrogen. Experiments were performed using methanol as a carbon source for denitrification and ferric chloride for an improved phosphorus removal. The studied continuous sand filter was a DynaSand filter marketed by Nordic Water Products AB. The filter has a surface area of 4.7 m2 and a maximum possible bed height of 6 m. The bed consisted of sand with 1.2-2 mm grain size. The tested bed heights were 3.5-4.8 m, and the hydraulic load varied between 5.4 and 24.5 m/h. The effluent from the Loudden treatment plant in Stockholm was supplied to the filter. Influent nitrate concentrations up to 20 mg N/l were tested and they decreased to 0.5-2 mg N/l. The methanol dosage was controlled by the measurement of nitrate continuously in the effluent by a dr Lange meter.

The denitrification rate followed a half order reaction down to low values of nitrate. Results showed that an effluent concentration of 0.15 mg P/l could easily be obtained. It was found that the influence of phosphate concentration is small on the denitrification rate if the phosphate concentration is above 0.1 mg P/l. The reject has a low sludge index which is favourable if the reject is returned to a sedimentation basin. The emission of nitrous gas (N2O) is very low. The installation makes it possible to use space efficiently, since polishing, phosphorus removal and denitrification can take place in the same unit. Already the phosphorus removal process reduces the need for process volume by 80% compared to a conventional process with flocculation and sedimentation basins.