bluuebunny/crossref_metadata_2025 huggingface dataset:
Assessment of pollution of the river Buriganga, Bangladesh, using a water quality model
Authors: Kamal Mir Mostafa , Malmgren-Hansen Anders , Badruzzaman A. B. M.
Published: May 2018

The River Buriganga, which runs past Dhaka City, is at present one of the most polluted rivers in Bangladesh. Dhaka City is very densely populated and will be one of the ten ‘Mega Cities’ by the year 2000. However, only a small fraction of the total wastewater being generated in the City is treated. Consequently, the amount of untreated wastes, both domestic and industrial, being released into the Buriganga is tremendous and is increasing day by day. Therefore, the objectives of this study were to investigate the status of the river water quality in terms of some cardinal water quality parameters, and to simulate the dissolved oxygen (DO) level using a water quality model. In order to fulfil the objectives, a comprehensive data acquisition programme – from both in situ and laboratory testing – was carried out. Then, a one-dimensional water quality model was developed for the Buriganga River system for a dry period of 1994-95. Different scenarios were tested to predict the most likely condition of the river. The results of the model simulations have replicated the alarming low DO level in the Buriganga. Option runs show that an integrated approach would be required to restore the river water quality with regard to biodegradable pollutants.
Effects of integrated stormwater management strategies on the combined sewer system and the wastewater treatment plant-river system
Authors: Welker A. , Leinweber U. , Klepiszewski K. , Schmitt T. G.
Published: May 2018

This is an investigation into possible changes to quantity and composition of sewage in the combined sewer system and the waste water treatment plant (WWTP) caused by new stormwater management strategies (mainly by disconnecting areas from the sewer system). Various scenarios were developed and the consequences on the water systems were calculated by using the simulation model KOSMO, in a fictional catchment.

The results of the combined sewer overflow-calculation show an enormous decrease of the overflow annual load for different parameters (COD, ammonia) by the reduction of impervious surfaces. Thus, the overflow concentrations of some parameters increase dramatically under these conditions, in particular the ammonia concentration might cause critical situations (e.g. sensitive receiving water).
Screening method for evaluation of inhibition of nitrification in Sweden
Authors: Jönsson K. , Jansen J. la C.
Published: May 2018

An investigation with respect to inhibition of nitrification of wastewater from 109 Swedish municipal wastewater treatment plants was performed. Flow proportional, 24-hour composite samples were collected during one week, and then analysed using the screening method. Inhibition of nitrification above 10% was found at only 20 plants. In general, the load of inhibiting substances is limited in Swedish municipal wastewater according to this study. The inhibition found is not connected to any special category of treatment plants with respect to the size of the plant. Neither was any general pattern of inhibition during the week found in this investigation. It was also shown that the screening method can be used for detecting small quantities of inhibiting substances if different dilutions of the same simple are analysed.
Hydrologic behaviour of stormwater infiltration trenches in a central urban area during 2¾ years of operation
Authors: Warnaars Eric , Larsen Anja Veldt , Jacobsen Per , Mikkelsen Peter Steen
Published: May 2018

Two infiltration trenches were constructed in a densely built-up area in central Copenhagen and equipped with on-line sensors measuring rain, runoff flow from the connected surfaces and water level in the trenches. The paper describes the field site, the measuring system and the results from an initial soil survey. Although the two trenches are placed close to each other they function rather differently, corresponding to effective soil permeabilities of 2·10−6 m/s in one trench and a factor 10 smaller in the other. During 2¾ years of measuring 89 events were recorded, of which 7 caused overflow. Analyses of falling water tables after rain indicated slight clogging, but this effect is less important than the general lack of knowledge about soil permeability for normal design situations. The results indicate that the stormwater infiltration in central urban areas with compressed soils and backfill is more feasible than previously anticipated.
Natural and Constructed Wetlands for Wastewater Treatment: Potentials and Problems
Authors: Gopal Brij
Published: May 2018

Wetlands are being considered increasingly important for wastewater treatment because of the ability of many wetland plants to absorb large amounts of nutrient and a variety of toxic substances. The paper highlights the physical, chemical and biological processes which contribute to the improvement of water quality, and the distinction between natural and constructed wetlands. The impacts of long-term wastewater disposal on the biotic changes, reduction in treatment efficiency, and wetland processes such as production of trace gases, are pointed out. Constraints in using wetlands, for wastewater treatment, such as poor understanding of the natural wetland functions and responses of native plants and animals to wastewater, particularly in developing countries, are briefly discussed. It is suggested that while the possibilities for using constructed wetlands based on native species for small communities are explored, greater emphasis should be laid on the restoration of lost and degraded wetlands, especially the river floodplains, lake littorals and coastal wetlands, which can help check pollution from non-point sources.
Assessing Denitrification Rate Limiting Factors in a Constructed Wetland Receiving Landfill Leachate
Authors: Kozub D. D. , Liehr S. K.
Published: May 2018

The focus of this research was to investigate denitrification in constructed wetlands to improve the nitrogen treatment capabilities of these systems. A free water surface flow constructed wetland located at the New Hanover County Solid Waste Management Facility, near Wilmington, North Carolina, USA, was used for this research. Field water sampling in conjunction with a laboratory acetylene block method was used to quantify nitrogen removals in the wetland. Background denitrification rates as well as potential denitrification rates using sodium acetate and sodium phosphate were measured in the laboratory. According to field measurements, average nitrate nitrogen loading and removal rates in the constructed wetland during 1997 were 11.1 ± 3.4 g N/m3/d and 4.5 ± 2.2 g N/m3/d, respectively. Denitrification rates measured in the laboratory with the addition of sodium acetate were higher than background denitrification rates while the addition of sodium phosphate had no effect on the denitrification rates. Results suggested denitrification in the wetland was limited by the availability of easily degradable sources of organic carbon. Background denitrification rates measured using the laboratory method were comparable to the nitrate nitrogen removal rates measured by field water sampling.
Treatment of Agricultural Wastewater in a Combined Tidal Flow-downflow Reed Bed System
Authors: Sun G. , Gray K. R. , Biddlestone A. J. , Cooper D. J.
Published: May 2018

In this study, the efficacy of a full-scale combined tidal flow-downflow reed bed system was tested for the treatment of agricultural wastewater with average BOD5 of 1100 mg/l and NH4-N of 329.5 mg/l. At a mean flow rate of 2.0 m3/d, the BOD5 and COD of the influent were reduced across the system by 97.6% and 71.3%, respectively. Considerable SS and PO4-P removals were also achieved. NH4-N was reduced by 93.1%. Nitrification proved to be the major process for NH4-N reduction. Although a further polishing treatment is needed, the average BOD5 and NH4-N levels of the treated wastewater were close to those frequently required in UK discharge consents. The highest BOD5, COD and NH4-N removals and oxygen consumption rate were achieved in the tidal flow stage of the combined system; this suggests that the rhythmical air/water movement in the matrix of the tidal flow beds can benefit the treatment by providing higher oxygen flux and more efficient utilisation of the available bed volume. Better results for BOD5, COD and NH4-N removals were obtained in downflow beds with water recirculation than in those without this recycle. Therefore the recirculation of effluent around each treatment stage is a suitable technique for improving the performance of downflow reed beds.
Role of Terrestrial Ecosystems Planted with Ligneous Species in M.H.E.A. System Receiving Urban Wastewaters
Authors: Nemcova M. , Cadelli D. , Radoux M.
Published: May 2018

Tests were carried out in a small-scale experimental plant. The system consisted of aquatic ecosystems without macrophytes (stage I) followed by semi-aquatic ecosystems planted with Typha latifolia L. (stage II). The outflow of stage II was evenly distributed into 10 units of terrestrial ecosystems (stage III), planted with ligneous species or without vegetation (control). The whole plant received a hydraulic load of 384 1/day of urban wastewaters. The net treatment area per person equivalent (PE) was 8 m2. The study focused on the evaluation of the role of terrestrial ecosystems mainly in tertiary treatment (nitrogen and phosphorus removal). Stages I and II with a surface area of 4 m2/PE assure a primary and secondary purification level that conforms with European standards. As for the tertiary treatment, removal efficiency remains inadequate. The primary and secondary efficiencies were considerably enhanced by installing terrestrial ecosystems after the two previous stages. The outflow water of all tested successions respects the European norms for suspended solids (35 mg/l), COD (125 mg/l) and BOD5 (25 mg/l). Concerning tertiary efficiency, the planted ecosystems systematically enhance nitrogen and phosphorus removal compared to the control sand. The succession with Salix has shown the best results. The outflow concentrations were 0.8 and 3.7 mg/l of total nitrogen and 1.8 and 1.3 mg/l of total phosphorus respectively (average values for periods 1995 and 1996). The control successions containing non-planted unit (sand) were significantly the least efficient for both nitrogen and phosphorus removal.
Use of the HDS System (Hydric Depuration with Soils) Associated to Other Constructed Wetlands Techniques for Public Water Supply
Authors: Salati E. , Salati E. , Salati E. , Tauk-Tornisielo S. M. , Brega D. F. , Bombonato C. J.
Published: May 2018

Two projects of water treatment for public water supply were developed and operated by using combined systems of constructed wetlands. One of the projects was carried out in the town of Analândia, São Paulo, Brazil and wetlands with floating aquatic plants associated to the HDS system were used. Nearly 6,480 inhabitants were supplied. The other conducted project was an experimental station in partnership with SABESP (São Paulo State Sanitation Agency / Brazil), for the pretreatment of 1,700 l.s−1 of waters from the Cotia River, which is used for the population's supply after conventional treatment at the Lower Cotia Water Treatment Station. For this pilot project, wetlands with emergents and floating plants associated to the HDS system were used. The proposed objectives were achieved in both projects.
Modelling large urban drainage systems in real time
Authors: Cluckie I. D. , Lane A. , Yuan J.
Published: May 2018

The interactions between rainfall and urban drainage systems (UDSs) are complex and must be considered as a whole in order to maximise control efficiency whilst at the same time achieving environmentally acceptable solutions. More rigorous standards, as a result of recent EU and UK legislation, are increasingly encouraging intervention in system management rather than more traditional passive procedures. To achieve these goals a global predictive real-time control (RTC) strategy is required, in which real-time flow prediction plays an important part in the provision of necessary first-hand information on system status in both current and predictive modes. This paper describes one such strategy, which differs from existing methods in the following ways: the novel way in which the UDS is represented; the algorithm used for model parameter identification; the strategies associated with the system output prediction; and the transfer function model used to represent the system. This transfer function model is a conceptually parameterised transfer function (CPTF) model, which by its nature falls into the category of lumped, dynamic, linear and conceptual although its structure takes the form of a non-conceptual transfer function model. The modelling approach is described as the RHINOS (Real-time urban Hydrological INfrastructure and Output modelling Strategy).
Model based evaluation of plant improvement strategies for biological nutrient removal
Authors: van Veldhuizen H. M. , van Loosdrecht M. C. M. , Brandse F. A.
Published: May 2018

An activated sludge model for biological N- and P-removal was developed, which describes anoxic and aerobic P-uptake based on bacterial metabolism. This model was tested in practice on two wastewater treatment plants, which are BCFS®-processes, which contain activated sludge with a high fraction of denitrifying P-removing bacteria (DPB's). The model appeared to be able to give an adequate description of the performance of these treatment plants under different conditions. If the process parameters are well defined almost no calibration of the biokinetic parameters was necessary. In the simulation of Dalfsen wwtp, which has a complex control scheme, it was possible to give an adequate simulation of the control actions and the concentration profiles in a rather simple way, showing that detailed simulation of these controllers was not necessary. With the calibrated model it was possible to analyse bottlenecks and give suggestions for upgrading of the concerned treatments plants. The simulation results were used in decisions on investments.
Direct parameter extraction from respirograms for wastewater and biomass characterization
Authors: Spanjers Henri , Takács Imre , Brouwer Harry
Published: May 2018

A method is proposed and described that calculates model parameters and components through a series of numerical transformations on respirometric data. The method is direct because it does not use a model optimisation technique. This direct respirogram evaluation (DRE) method separates the respirogram into individual components, and calculates maximum respiration rate, saturation coefficient and yield factor for the components. An advantage of the DRE method is the simplicity; there are no complications involving modelling, optimisation, and model identifiability. The calculations are model independent, even though the principle implies the Monod saturation term. The most important limitation is that only certain types of respirograms can be identified, that is: individual components must be dominant at a critical stage of their oxidation. The DRE method is tested on simulated respirograms and a number of real respirograms of various characteristics, and the results from the latter are compared to those from a parameter optimisation method. It is concluded that the two methods are not always in agreement, especially when a component is present in a minor fraction.
Uncertainty in return period analysis of combined sewer overflow effects using embedded Monte Carlo simulations
Authors: Grum Morten , Aalderink R. Hans
Published: May 2018

The return periods of detrimental effects are often used as design criteria in urban storm water management. Considerable uncertainty is associated with the models used. This is either ignored or pooled with the inherent event to event variation such as rainfall depth. It is here argued that uncertainty and inherent event to event variation should be treated separately, in providing engineers and managers with the distributions of return periods. It is then possible to base management decisions on knowledge of both the expected return periods and their corresponding confidence limits. It is further argued that the traditional pooling of inherent variation and uncertainty leads to meaningless return period curves with little engineering value.

All quantities which are described by a probability distribution are placed in either of the two layers: an inner layer consisting of quantities varying from event to event and an outer layer consisting of uncertain but constant quantities. For each set of random realisation of the values in the outer uncertainty layer a full set of Monte Carlo simulations for the inner inherent variations layer is performed resulting in a return period curve. The many samplings in the outer layer results in a band of return period curves representing the distribution of return periods for which confidence limits may be calculated. The general methodology is here described as Embedded Error Propagation and its current implementation as Embedded Monte Carlo Simulations.

The approach is demonstrated in an integrated setting involving models for rainfall characteristics, combined sewer overflow (CSO) loads and impacts on the surface water dissolved oxygen (DO). CSO loads are modelled using event lumped non-linear regression models with rainfall as input and with overflow volume, duration and relevant event mean concentrations as output. Oxygen depletion in the surface water is described using a dynamic model including oxidation of dissolved chemical oxygen demand (COD) and nitrification. Conversion models had to be developed to integrate the output variables of the CSO model with the input variables of the surface water model. The parameters of all the models were estimated from observed data on rainfall, CSO load and surface water impacts. The background conditions of the surface water were modified creating a hypothetical, but more general and relevant case to present the methodology. Focus is in this paper on chemical effects of CSO on a surface water. The proposed distinction between event to event variation and uncertainty and the associated methodology are equally valid to the return period analysis of flooding.
Selection aid of alternative techniques in urban storm drainage - proposition of an expert system
Authors: Barraud S. , Azzout Y. , Cres F. N. , Chocat B.
Published: May 2018

The choice of BMPs in urban stormwater drainage is most often made with a poor understanding of site constraints, and of the possibilities afforded by these techniques. This leads to extra costs and malfunctioning. To reach feasible choices, we have formalised a decision-making process, taking into account multiple criteria and the large number of partners involved in that kind of process. We have then developed a decision-aiding procedure split up into two phases: an elimination phase permits us to exclude solutions which are identified as unworkable according to site considerations and a decision phase which allows the decision makers to compare and at least to choose a scenario built up with feasible solutions. This paper more particularly deals with the first phase. This elimination phase, which is suitable for an expert system type of representation, has been implemented using a software called DELTANOE constructed for operational design issues but also for pedagogic purposes including conception, realisation, maintenance and management recommendations as well as sketches and photo examples. After presenting the context and basic principles of the elimination phase, we present the way the associated tool has been constructed and validated.
Balancing: the economic approach to sustainable water management
Authors: Braden J. B. , van Ierland E. C.
Published: May 2018

The economic approach to the management of water resources and systems is one of balancing competing objectives. Economics provides a framework for weighing those objectives in determining how much of each to strive for based on concerns for current use as well as long-term sustainability. More importantly, economics provides insight into policies that promote sustainable development by virtue of aligning the incentives of individuals with the long-run interests of the community. This paper shows how economic principles can be applied to reinforce sustainable choices concerning water supply, waste water treatment, irrigation, and watershed management.
Selection and evaluation of a new concept of water supply for “IJburg” Amsterdam
Authors: van der Hoek J. P. , Dijkman B. J. , Terpstra G. J. , Uitzinger M. J. , van Dillen M. R. B.
Published: May 2018

The city of Amsterdam is going to build a new housing estate: IJburg. About 18,000 houses will be built and finally 45,000 people will live in IJburg. An important objective is to realize a sustainable housing estate: the design is focused on water and energy saving, and the use of sustainable building materials. An alternative water supply system, in which household water is used besides drinking water, may be an important contribution to this ambition. Household water can be used for toilet flushing, for washing clothes or for both. Amsterdam Water Supply developed five scenarios for such an alternative water supply system. Water saving and supply of two types of water are key elements in these scenarios. Based on a comprehensive selection in which public health aspects, technical feasibility, legislation, acceptance by the public, costs and environmental impact were used as criteria, the optimum scenario was chosen: a dual water system, supplying drinking water from the existing drinking water production plants, and supplying household water for toilet flushing and washing, produced from a local surface water, the IJ-lake.
A feasibility study on ultrafiltration of industrial effluents
Authors: Roeleveld P. J. , Maaskant W.
Published: May 2018

Short-term membrane tests were carried out to determine the feasibility of the application of ultrafiltration for the reuse of effluent from industrial treatment plants. Ultrafiltration proved to be a suitable technology for the treatment and reuse of effluent and with dead-end filtration high permeate fluxes were achieved. An adequate cleaning procedure for the membranes is required to maintain constant and high permeate fluxes. The feasibility is partly determined by the suspended solids concentration in the effluent. For the recirculation of effluent with low suspended solid concentrations the operational costs are comparable to or lower than the costs of drinking water and groundwater. If a high temperature of the process water is required and the thermal energy in the effluent can be reused, an additional saving can be obtained in the total costs per cubic metre water. The technical feasibility of the reuse of effluent depends on the type of industry, the wastewater characteristics and the required permeate quality for reuse. The economic feasibility of effluent reuse will be determined by the present water price, trends in the costs of drinking water or abstraction of groundwater and further developments in the costs of membrane technology.
Closed wastewater system in the tapioca industry in vietnam
Authors: Hien P. G. , Oanh L. T. K. , Viet N. T. , Lettinga G.
Published: May 2018

Wastewater from tapioca processing factory containing high COD (11,077-19,083 mg/l), SS (4,180-7,600 mg/l) and low pH (4.33-5.60) still causes heavy pollution to receiving water in South Vietnam. Closing the water circuit in the tapioca industries represents a very attractive option for eliminating pollution problems and the reuse of treated wastewater and solid wastes. The investigated and presently occasionally already implemented system consists of primary sedimentation tank, anaerobic treatment using UASB-reactors, aeration tanks using attached growth reactor and oxidation ponds system. Under laboratory conditions, organic loading rates applied in UASB-reactors are up to 40,35 kg COD/m3.d with treatment efficiency of 90-95%, reducing the COD concentration from up to 13,449 mg/l to 624-780 mg/l. The final effluent COD (sol.) after treatment in the pond system operated at hydraulic retention time of 12-20 days is lower than 10 mg/l. This effluent is suited very well either for use in agriculture or in the factory.
Low temperature treatment of domestic sewage in upflow anaerobic sludge blanket and anaerobic hybrid reactors
Authors: Elmitwalli Tarek A. , Zandvoort Marcel H. , Zeeman Grietje , Bruning Harry , Lettinga Gatze
Published: May 2018

The treatment of sewage at a temperature of 13°C was investigated in three reactors (each 3.84 litre) a UASB and two anaerobic hybrid (AH) reactors with small sludge granules with an average diameter of 0.73 mm. The media used in the AH reactors were vertical polyurethane foam sheets. The reactors were operated at a HRT of 8 h. The use of small sludge granules and operating the reactors at low upflow velocity (1.8 m/d) improved suspended COD removal efficiencies for the UASB reactor. Moreover, the use of sheets in the AH reactors significantly increased suspended COD removal efficiencies as compared to the UASB and reached to 87% for pre-settled sewage treatment. The treatment of pre-settled sewage instead of raw sewage in AH reactors significantly increased colloidal and dissolved COD removal efficiencies with 13% and 12% respectively and colloidal COD removal efficiency for the UASB reactor with 13%. At ‘steady state’ for pre-settled sewage treatment, the AH reactors removed 64% of the total COD which is significantly higher by 4% than the UASB reactor. Therefore, the anaerobic treatment of domestic sewage at low temperature can be improved by treating pre-settled sewage in shallow AH reactors containing small sludge granules.
Primary effluent filtration in small-scale installations
Authors: van Buuren J. C. L. , Abusam A. , Zeeman G. , Lettinga G.
Published: May 2018

This paper reviews recent technological developments in the filtration of primary effluent. Various studies show that single stage intermittent sand filters attain removal efficiencies of 90% COD, 95% BOD5, 30% TN, 40% TP and 99-99.9% FC at maximum BOD5 loads of around 10 g.m−2.d−1 and hydraulic loads of 5-10 cm.d−1. The permissible organic load can be enhanced by measures such as improved aeration and the use of multilayer filters. Nitrogen removal can be enhanced to 70% by adding a C-source to the filter material or by using two-stage post- and pre-denitrification systems. High organic loading rates (up to around 100 g BOD5.m−2.d−1) are possible with aerated adsorbent foam as a medium.
An Aesthetic Quality Index for Barcelona's Water Supply
Authors: Bernal A. , Cardeñoso R. , Fabrellas C. , Matia L. , Salvatella N.
Published: May 2018

The application of an aesthetic quality index is proposed for distribution water. This index is expressed by a dimensionless number between zero and ten and it is calculated by a formula in which taste and odour, turbidity and colour take part. A sub-index has previously been defined for each of these parameters and the global index is a weighted average of all of them. The taste and odour are determined by Flavour Profile Analysis.
Study of factors affecting simultaneous nitrification and denitrification (SND)
Authors: Pochana Klangduen , Keller Jürg
Published: May 2018

Experiments have been performed to gain an understanding of the conditions and processes governing the occurrence of SND in activated sludge systems. Sequencing batch reactors (SBRs) have been operated under controlled conditions using the wastewater from the first anaerobic pond in an abattoir wastewater treatment plant. Under specific circumstances, up to 95% of total nitrogen removal through SND has been found in the system. Carbon source and oxygen concentrations were found to be important process parameters. The addition of acetate as an external carbon source resulted in a significant increase of SND activity in the system. Stepwise change of DO concentration has also been observed in this study. Experiments to determine the effect of the floc size on SND have been performed in order to test the hypothesis that SND is a physical phenomenon, governed by the diffusion of oxygen into the activated sludge flocs. Initial results support this hypothesis but further experimental confirmation is still required.
A survey of prefermenter design, operation and performance in Australia and Canada
Authors: Münch E. v. , Koch F. A.
Published: May 2018

We have compiled recent data from nine full-scale prefermenters in Australia and Canada. Using this data, we compare their design, operation and performance. The design parameters of importance are the prefermenter configuration, the fraction of total flow that is fed to the prefermenter, the prefermenter volume and the hydraulic and solids residence time (HRT and SRT). With respect to prefermenter performance, we use the rate of volatile fatty acid (VFA) production to compare prefermenter efficiency. A number of other performance indicators are also used to compare the output of the prefermenters (for example total mass of VFA produced). All side-stream prefermenters compared in this study have relatively similar rates of VFA production (typically 14 to 28 mg/L/h), which indicates that they all perform with similar efficiencies, regardless of their respective type.
Optimizing Biological Nutrient Removal in anoxic zones
Authors: Stevens Gerald M. , Barnard James L. , Rabinowitz Barry
Published: May 2018

During the initial years of the development of Biological Nutrient Removal (BNR) technology, it was assumed that the bacterial species responsible of the removal of phosphorus (BioP organisms) could not use nitrates as a final electron acceptor and could thus not denitrify. The carbon taken up in the form of Volatile Fatty Acids (VFA) in the anaerobic zone was thus deemed to be unavailable for denitrification in the anoxic zone. This was reinforced through experiments in which BioP organisms cultured in the high-rate Phoredox system in which no nitrification took place, did not denitrify when nitrates were added. Many researchers (e.g. Dold and Barker) have since shown that in BNR systems such as the 3-Stage Bardempho system, where nitrates are recycled to the anoxic zone which follows the anaerobic zone, a high degree of phosphorus uptake through denitrification does occur. In addition, the partial diversion of primary effluent directly to the anoxic zone has significantly improved phosphorus uptake under anoxic conditions.

Full-scale operations at the Westbank, British Columbia, plant showed a substantial uptake of phosphorus in the anoxic zone in the absence of oxygen. The Westbank configuration includes side stream primary sludge fermentation, VFA rich fermenter supernatant addition directly to the anaerobic zone and diversion of a portion of primary effluent to the anoxic zone. This configuration stimulates P-uptake under anoxic conditions, demonstrates the efficient use of carbon and is instrumental in achieving an annual average effluent Total-P concentration of less than 0.17 mg/l.

The phenomenon of denitrification by BioP organisms was included in the Biowin Model developed by Dold (Biowin Manual). This paper describes experiments and full-scale plant observations to establish the role of BioP organisms in the removal of nitrates in the anoxic zone of a plant which also receives a portion of the primary effluent and verification of the Biowin model.
Nitrogen removal from wastewater treatment lagoons
Authors: Hurse Timothy J. , Connor Michael A.
Published: May 2018

In an attempt to gain a better understanding of ammonia and nitrogen removal processes in multi-pond wastewater treatment lagoons, an analysis was carried out of data obtained during regular monitoring of Lagoon 115E at the Western Treatment Plant in Melbourne. To do this, a contour plot approach was developed that enables the data to be displayed as a function of pond number and date. Superimposition of contour plots for different parameters enabled the dependence of ammonia and nitrogen removal rates on various lagoon characteristics to be readily assessed. The importance of nitrification as an ammonia removal mechanism was confirmed. Temperature, dissolved oxygen concentration and algal concentration all had a significant influence on whether or not sizeable nitrifier populations developed and persisted in lagoon waters. The analysis made it evident that a better understanding of microbial, chemical and physical processes in lagoons is needed before their nitrogen removal capabilities can be predicted with confidence.
Activity of Geranyl Pyrophosphate Synthase in Musty Odor Producing Cyanobacteria
Authors: Oikawa E. , Ishibashi Y.
Published: May 2018

The activity of geranyl pyrophosphate (GPP) synthase of several cyanobacteria has been evaluated by thin layer chromatography (TLC) and liquid scintillation counter. Two kinds of Phormidium tenue (P. tenue) wild strains and two kinds of pure strains P. tenue and Oscillatoria limnetica (O. limnetica) were used in the experiments. Harvested cells were disrupted by ultrasonic and ultracentrifuged at 100,000 X g for 60 min at 4°C. The supernatant and pellet were used for GPP synthase assay. GPP synthase activity was first determined from P. tenue. The highest enzymatic activity was observed in the supernatant ultracentrifuged at 100,000 X g, therefore this enzyme was present in the cytoplasm. The supernatant was fractionated by ammonium sulfate and the enzymatic activity of 30% ammonium sulfate fractionation was twice the strength compared with and without ammonium sulfate fractionation. 2-Methylisoborneol (MIB) production did not correspond to the activity of GPP synthase as determined by the comparison of enzymatic activity between odor producing and non-producing strains.
Evaluation of Public Health Related Quality Aspects of Materials, Coming into Contact with Drinking Water – Odour and Flavour Tests in Particular
Authors: van der Jagt Hans
Published: May 2018

Objectionable odours and flavours in drinking water are a constant concern to consumers and public water suppliers. The organoleptic properties of drinking water can be naturally induced or man-made. In this paper characteristics and causes of odours and flavours are evaluated. Two methods for determining odour and flavour, in relation to the EC Directive 80/778, are described. In the Netherlands, the Netherlands Waterworks Testing and Research Institute (Kiwa) is responsible for the testing and certification of materials used in the production and distribution of drinking water. A study was undertaken to develop standards for odours and flavours in water under well defined conditions. Results of round robin tests in the period 1994 through 1997, demonstrated a considerable improvement in these methods. A valuable strategy is available for a successful localization of the causes of flavours and odours to protect consumers against health risks. Accordingly, these analytical techniques can give a complete view of impurities derived from distribution systems.
Study of the Possible Origins of Chlorinous Taste and Odour Episodes in a Distribution Network
Authors: Welte B. , Montiel A.
Published: May 2018

Occasionally in winter some inhabitants of the city of Paris complain of a bad chlorinous odour when the chlorine residual in the water distribution network is 0.1 mg/l. Several hypotheses have been made. Many taste and odour profiles have been made on one plant and aminoacids and aldehydes have been analysed. Chlorination of urea has not led to the chlorinous taste. We think that these odours are due to trichloramine, which is produced by chlorination of some organo nitrogen compounds with a slow kinetics of formation during winter. Results show that the combined chlorine level is constant with time and we have reproduced this offensive odour but the origin does not seem to be aldehydes.
Biological Origins of Off-flavours in Fish and Crustaceans
Authors: Whitfield F. B.
Published: May 2018

Edible fish and crustaceans, either of salt or of freshwater origin, are occasionally affected by off-flavours that can be related to the animal's diet or the natural environment in which they live. Off-flavours include petroleum and blackberry-like flavours in salmon and cod; garlic-like flavours in prawns and sand-lobsters; iodoform-like flavours in prawns, shrimp and fish; and muddy and earthy flavours in brackish-water fish and shrimp. Knowing the source of such off-flavours will in some cases assist processors in taking remedial action. This paper will discuss the possible biochemical pathways to five of these off-flavour compounds and, in addition, will provide evidence as to the likely marine organisms responsible for their formation. Methods to reduce the severity of such off-flavour incidents will also be described.
Mercury Removal from Wastewater by Steamed Hoof Powder
Authors: Ansari M. H. , Deshkar A. M. , Kelkar P. S. , Dharmadhikari D. M. , Hasan M. Z. , Paramasivam R.
Published: May 2018

Steamed Hoof Powder (SHP), size < 53μ, was observed to have high adsorption capacity for Hg(II) with >95% removal from a solution containing 100 mg/L of Hg(II) with only 0.1% (W/V) concentration of SHP. The SHP has good settling properties and gives clear and odour free effluent. Studies indicate that pH values between 2 and 10 have no effect on the adsorption of Hg(II) on SHP. Light metal ions like Na+, K+, Ca2+ and Mg2+ up to concentrations of 500 mg/L and heavy metals like Cu2+, Zn2+, Cd2+, Co2+, Pb2+, Ni2+, Mn2+, Cr3+, Cr6+, Fe2+ and Fe3+ up to concentrations of 100 mg/L do not interfere with the adsorption process. Anions like sulphate, acetate and phosphate up to concentrations of 200 mg/L do not interfere. Chloride interferes in the adsorption process when Hg(II) concentration is above 9.7 mg/L. The adsorption equilibrium was established within two hours. Studies indicate that adsorption occurs on the surface sites of the adsorbent.
Phytoplankton Activities in Hypersaline, Anoxic Conditions. I—Dynamics of Phytoplankton Succession in the Solar Lake (Taba, Egypt)
Authors: Ali Gamila H.
Published: May 2018

The seasonal and vertical distribution of planktonic algae in the Solar Lake (Taba–Egypt) and their relation to some aquatic environmental factors were discussed through the period (Sep. 1996–Aug. 1997). Surface water analysis showed that no remarkable changes were observed in nitrate, silicate and iron, while turbidity, salinity and chloride were changed according to the season. In water column profile, H2S, temperature and salinity showed clear variations between stratification and holomixis. Maximum salinity (199‰) was recorded during stratification at 3-4 m depth. Stratification (Oct-June) appears clearly with changes in temperature (surface 16°C, thermocline up to 53.3°C and the bottom temperature around 47.7°C). Cyanobacterial mats of the Solar Lake are classified into two layers, the upper layer was dominated by coccoide forms while the lower was dominated by filamentous forms. During the period of study, 39 algal species were identified among which were 17 species of Cyanobacteria, 18 species of Bacillariophyta and 2 species of either Chlorophyta or Dinoflagellates.
Appropriate Technologies for Effective Management of Industrial and Domestic Waste Waters: The Decentralised Approach
Authors: van Lier Jules B. , Lettinga Gatze
Published: May 2018

The increasing scarcity of clean water sets the need for appropriate management of available water resources. Particularly regions suffering from a lack of water urgently need integrated environmental protection and resource conservation (EP&RC) technologies in order to enable effective management of the available water resources. EP&RC-concepts focus on a minimum of consumptive use of energy, chemicals, and water and a maximum of reuse of treated wastewater and of residues produced from the pollutants present in the wastewater. Consequently, by implementing these concepts, instead of a social threat, waste(water)s like sewage and industrial effluents become an important resource for water, fertilisers, soil conditioners and to some extent also energy. In addition, a bridge is made between environmental protection and agriculture practice, stimulating (urban) agriculture in the neighbourhood of large cities.

Anaerobic treatment is considered as the core technology for mineralising organic compounds in waste(water) streams. Additional technologies are required to comply with the reuse criteria. Some examples of possible EP&RC concepts, using the anaerobic treatment technology for the reclamation of domestic sewage are discussed.
A microelectrode study of redox potential change in biofilms
Authors: Bishop Paul L. , Yu Tong
Published: May 2018

In this study, we examined the stratification of microbial processes and the associated redox potential changes in biofilms using microelectrode techniques. Two types of biofilms, each with a different combination of microbial processes, were examined. The first type carried aerobic oxidation and sulfate reduction, while the second one provided aerobic oxidation and nitrification. The microelectrodes used were oxygen, sulfide, ammonium, pH and redox potential microelectrodes. The results of this study provide the following new experimental evidence: (1) The aerobic/sulfate-reducing biofilm had a clearly stratified structure with depth. In this biofilm, aerobic oxidation took place only in a shallow layer near the surface and sulfate reduction occurred in the deeper anoxic zone. The boundary between these two processes was well defined. (2) The aerobic/nitrifying biofilm also had a stratified structure with depth. In this biofilm, though aerobic oxidation took place throughout the biofilm depth, more nitrification occurred in the deeper section of the biofilm. The boundary between these two processes, however, was less well defined. (3) Redox potential could be an indicator for the existence of certain microbial processes in biofilms. The redox potential profile changes were correlated to shifts of microbial processes in both types of biofilms. The redox potential profiles in these biofilms can be used to elucidate the stratification of microbial processes in the biofilms.
1H NMR characterisation of the diffusional properties of methanogenic granular sludge
Authors: Lens P. , Vergeldt F. , Lettinga G. , Van As H.
Published: May 2018

The diffusive properties of mesophilic methanogenic granular sludge have been studied using diffusion analysis by relaxation time separated pulsed field gradient nuclear magnetic resonance (DARTS PFG NMR) spectroscopy. NMR measurements were performed at 22°C with 10 ml granular sludge at a magnetic field strength of 0.5 T (20 MHz resonance frequency for protons). Spin-spin relaxation (T2) time measurements indicate that three 1H populations can be distinguished in methanogenic granular sludge beds, corresponding to water in three different environments. The T2 relaxation time measurements clearly differentiate the extragranular water (T2 ≈ 1000 ms) from the water present in the granular matrix (T2 = 40-100 ms) and bacterial cell associated water (T2 = 10-15 ms). Self-diffusion coefficient measurements at 22°C of the different 1H-water populations as the tracer show that methanogenic granular sludge does not contain one unique diffusion coefficient. The observed distribution of self-diffusion coefficients varies between 1.1 × 10−9 m2/s (bacterial cell associated water) and 2.1 × 10−9 m2/s (matrix associated water).
Observation of thick biofilm accumulation and structure in porous media and corresponding hydrodynamic and mass transfer effects
Authors: Sharp R. R. , Cunningham A. B. , Komlos J. , Billmayer J.
Published: May 2018

A series of flat plate, porous media reactor studies was performed to characterize the development and structure of thick biofilms in porous media and the subsequent effects on porous media hydrodynamics and mass transport variables including average pore velocity, hydrodynamic dispersivity, and (dye tracer) breakthrough curve features. Biofilms composed of either a mucoid strain of Pseudomonas aeruginosa or a non-mucoid strain of Ps. aeruginosa were established in the reactors over a 2-3 week period. Analysis of porous media biofilms was performed using a combination of image analysis, photography, microbial vital stains, enumerations, and microscopy. Bulk fluid flow and flow channel distribution in the porous media/biofilm matrix were monitored by imaging a pulse of nigrosine dye. Hydrodynamics of the systems were determined by evaluating fluorescein dye breakthrough curves. Destructive sampling of the flat plate reactors at the end of each study provided additional information on the distribution and cell density of the porous media biofilms. Imaging results indicated the creation and closure of flow channels within the biofilm/porous media matrix for both mucoid and non-mucoid strains. Both systems exhibited accelerated tracer breakthrough and slightly increased hydrodynamic dispersivity as the biofilm matrix developed. Gray scale analysis of nigrosine pulses, along with fluorescein dye studies, suggests that biofilm development transforms the flow regime within the reactor from well defined porous media flow with a symmetric breakthrough curve to a skewed breakthrough curve with accelerated time to breakthrough.
Modelling denitrification in a moving bed of porous carriers from a low-loaded wastewater treatment plant
Authors: Maurer M. , Fux C. , Lange D. , Siegrist H.
Published: May 2018

A model was developed to describe hydrolysis in a moving bed with polyurethane foam carriers under anoxic conditions. It is formulated as a two-box model and structured into bulk and carrier compartments linked by mass transfer processes for solutes and particles. The biological processes consist of the anoxic growth and decay of heterotrophic organisms and hydrolysis of the slowly biodegradable substrate. Kinetic and stoichiometric parameters are taken from Activated Sludge Model No. 2 (Henze et al., 1995). Parameter estimations based on 24 batch experiments resulted in anoxic hydrolysis rates of 3.9 d−1 (at 20°C) and 2.6 d−1 (at 10°C).

The mass transfer coefficient for solutes was determined from the mixing of an inert tracer to be 0.3 m d−1. Measurements of the enzymatic activity of α-, β-glucosidase and esterases confirmed that 90% of the activity involves the carriers. In conjunction with the finding that the absorption capacity of the carriers for slowly biodegradable substrate is high, it can be concluded that the hydrolysis takes place principally within the carriers.
Mechanism of Degradation of Wool Wax in the Anaerobic Treatment of Woolscouring Wastewater
Authors: Gutiérrez Soledad , Hernández Alberto , Viñas María
Published: May 2018

Results of the anaerobic digestion of a woolscouring wastewater treatment and some considerations about the anaerobic degradation mechanisms of wool wax, are presented. A 57 litre anaerobic baffled reactor (ABR) was operated with woolscouring effluent. When organic load varied from 3 to 5 kg COD/m3 d, COD and grease removal ranged from 40 to 55% and 50 to 65%, respectively. With centrifuged effluent, COD removal was 45% to 60%. A 300 m3 ABR was built and operated during two years based on the previous laboratory results. COD removal was between 45% to 18% with organic load of 3 to 10 kg COD/m3 d. With centrifuged effluent, COD efficiencies ranged between 72% and 47%. No inhibition by long chain fatty acids was observed. Considering the results of grease content determination and TLC analysis in both reactors, it could be assumed that wool wax is hydrolyzed forming sterols and free fatty acids and that free fatty acids are degraded while sterols are accumulated in the sludge.