bluuebunny/crossref_metadata_2025 huggingface dataset:
The use of microsensors to determine population distributions in UASB aggregates
Authors: Lens Piet , de Beer Dirk , Cronenberg Carel , Ottengraf Simon , Verstraete Willy
Published: May 2018

Glucose and pH microprofiles in UASB aggregates were interpreted with respect to the population distribution of fermentative and methanogenic bacteria. In order to map the activity distribution of these bacteria, microprofiles were measured with different substrates (glucose, propionate and acetate) and at varying buffer capacities of the medium. The measurements were compared to calculated microprofiles, in which the spatial location of the activities was varied. The results suggested an inhomogenic activity distribution in the aggregates investigated: fermentatives were located dominantly at the outer 200-300 μm whereas methanogens were homogeneously distributed over the aggregate.
Science, technology, and willingness to pay in ocean disposal of wastes: America's misplaced search for equity. An introductory case study of Los Angeles
Authors: Garber William F. , Gunnerson Charles G.
Published: May 2018

Legislation termed “environmental” in the U.S.A., and concerned with the effects of contaminants upon air, land and water resources, is based upon economic equity rather than environmental improvement. Environmental improvement may or may not result, and the environment of societal and human needs is negatively affected by the very large resource commitment necessary. The requirement of the thermodynamically impossible “zero discharge” goal, as well as cancer to determine limits discards science and engineering for politically and popularly determined goals. To the extent that U.S.A. standards are accepted by other nations in the World, this unscientific approach is of concern to all. Change from the present approach will be very difficult because of the popularity of the present laws, and benefit from the present arrangement to so many workers in the field. Post Audits of the actual net overall environmental impacts of changes required and being made under the laws must be made to achieve change.
Modelling the coliforms inactivation rates in the Cantabrian sea (bay of Biscay) from in situ and laboratory determinations of T90
Authors: Canteras Juan C. , Juanes José A. , Pérez Luisa , Koev Kalin N.
Published: May 2018

Precommissioning studies of proposed outfalls along the north coast of Spain included in situ and laboratory determinations of T90 values directed at the development of a local-specific inactivation model.

The effect of salinity, light intensity, temperature and depredation on inactivation (T90) of Escherichia coli, was studied in unifactorial experiments carried out in the laboratory. The values of T90 obtained fitted the exponential model of die-off for the first three variables (salinity, light, temperature: R > 0.93). Light intensity showed the greatest bactericidal effect, with T90 values near or lower than 1 hour, when light radiation was greater than 120 Wm−2. The logarithm of T90 showed a linear relationship with each one of these three factors. Nevertheless, the global relationship which best fits the values obtained was not linear in its coefficients.

The values of T90 estimated from experiments in situ, carried out in summer (33.6 min) and winter (116.8 min), reflected the seasonal differences in the environmental conditions in this zone, mainly from light intensity. Differences between these values and those obtained applying the model pointed out the need to study in depth the effect of light on the bacterial die-off in natural systems.
Structured modelling of denitrification intermediates
Authors: Wild D. , von Schulthess R. , Gujer W.
Published: May 2018

Two mathematical models have been formulated to describe the turnover of denitrification intermediates. Batch experiments with different nitrite concentrations have been performed to calibrate the models. In these experiments the concentration of oxygen in the reactor has been varied from 4 g O2m−3 to 0 g O2m−3. Model I includes the reduction of nitrate, nitrite, and nitrous oxide. Non-competitive inhibition of these processes by oxygen and nitrite has been included in the kinetics. The estimated parameters indicate that the net production of N2O at low oxygen concentrations can be explained by different oxygen inhibition of the three reduction steps. Model II works with structured biomass to improve the description of the data from the experiments. In addition to Model I, the synthesis and decay of denitrification enzymes are described to allow correct predictions of nitrate, nitrite and N2O concentrations. Model II has been used to simulate the effect of cell saturation with enzymes in a wastewater treatment process. Low dissolved oxygen concentrations in the anoxic reactor reduce the denitrification efficiency equally by inhibiting enzyme activity and enzyme synthesis: at 0.5 gm−3 O2 enzyme decay causes a cell saturation of below 40%. The benefits of modelling with structured biomass are shown: The comprehension of experimental observations is improved, and plant design and operation can be optimized. However, the multitude of unknown parameters still may restrict the application of complex models.
Estimation of the rate of slowly biodegradable COD (SBCOD) hydrolysis under anaerobic, anoxic and aerobic conditions by experiments using starch as model substrate
Authors: Mino Takashi , San Pedro Delfin C. , Matsuo Tomonori
Published: May 2018

The hydrolysis rates under anaerobic, anoxic and aerobic conditions are studied by using starch as a model organic substrate representing the slowly biodegradable COD. An analytical method, the starch-iodine complex formation method, was introduced to distinguish the polymer starch and its hydrolysis products, and it was applied to estimate the hydrolysis rates in an activated sludge mixed culture, two bacterial pure cultures (Bacillus amyloliquefaciens and Aeromonas hydrophila) or a pure enzyme (α-amylase) system. The rate of starch hydrolysis was found to be independent of the electron acceptor conditions. The starch hydrolysis rate constant of the activated sludge was not affected by the biomass concentration, which indicates that the starch hydrolysis in the activated sludge process follows surface limited adsorption reaction kinetics.
Quantitative comparison of the influxes of nutrients and organic carbon into the Sea of Marmara both from anthropogenic sources and from the Black Sea
Authors: Tugrul Suleyman , Polat Colpan
Published: May 2018

The Sea of Marmara, an intercontinental basin with two narrow and shallow straits permitting the exchange of the Mediterranean and Black Sea waters, receives 2.8×104 tons TP (total phosphorus), 2.7×105 tons TN (total nitrogen) and 1.9×106 tons TOC (total organic carbon) per year from the Black Sea inflow, from the lower layer by vertical mixing and from anthropogenic inputs of various origins including riverine discharges. The Black Sea input through the Bosphorus constitutes about 35, 64 and 77 %, respectively, of the total annual loads of TP, TN and TOC entering the Marmara surface waters. Pollution loadings from Istanbul make up a major fraction (40-65%) of the total anthropogenic discharges. The biochemical properties of the productive Marmara upper layer appear to be dominated by the inputs both from its lower layer by vertical mixing and from the Black Sea throughout the year. Pollution discharges from Istanbul have secondary importance for the nutrient and organic carbon pools of the Marmara Sea; however, the land-based chemical pollution has drastically modified the ecosystem of coastal margins and semi-enclosed bays (e.g. Golden Horn, Izmit and Gemlik) where water exchanges with the open sea are limited. Biologically labile nutrients increasingly exported from the Black Sea in the spring-early summer, are compensated by importation from the Marmara Sea through the Bosphorus underflow. The less labile dissolved organic nitrogen and carbon input from the Black Sea appears to reach as far as the Aegean basin of the Northeastern Mediterranean in 4-5 months without contributing to the net production in the Marmara Sea.
A one-dimensional model for a secondary settling tank including density current and short-circuiting
Authors: Dupont René , Dahl Claus
Published: May 2018

This paper presents a dynamic one-dimensional flux model for the secondary settling tank which is suitable for use with the latest innovations in models for activated sludge tanks, and which takes into account observed effects of density current and short-circuiting. The components of the influent to the settling tank are divided into three fractions. Soluble components, non-settleable particulate components (primary particles), and settleable particulate components. (macroflocs). Soluble components and primary particles are considered to follow the hydraulic flow in the settling tank. The transport of macroflocs in the settling tank is modelled according to the traditional flux theory on a layer model of the settling tank extended with a model for density current and short-circuiting. For modelling of the density current in the inlet region of the settler a dynamic inlet height is introduced. The short-circuiting is modelled by the introduction of a factor which accounts for the dilution in the suspended solids concentration at the bottom of the settling tank down to the concentration in the return sludge flow. Settling velocities of the macroflocs for both free and hindered sedimentation are measured, and a new model for the settling velocity is proposed. The model is validated with data from the wastewater treatment plant Lynetten, Copenhagen, Denmark. It was found that the suspended sludge concentration profile and the suspended sludge concentration in the return sludge were predicted well with the model.
An evaluation of pollutant removal from secondary treated sewage effluent using a constructed wetland system
Authors: Thomas P. R. , Glover P. , Kalaroopan T.
Published: May 2018

Pilot scale investigations were carried out to examine the pollutant removal efficiency of a constructed wetland receiving secondary treated sewage effluent. Four constructed wetland cells were established, three of them planted with either Schoenoplectus validus, Juncus ingens or both species of macrophytes, and the fourth serving as an unvegetated control cell. Although there was a significant improvement in the effluent quality during the initial ten month period of monitoring, results to date have not indicated any overall trend for pollutant removal by a particular plant species. Biochemical oxygen demand and chemical oxygen demand removals averaged between 71-75% while suspended solids removals were around 85% in the macrophyte cells. Ammonia reductions were in the range 17-24% but better nitrate reductions between 65-80% were obtained. Phosphorus removal has been low (13%) in all four of the wetland cells and bore hole samples have shown no groundwater contamination with nitrogen or phosphorus from the wetland system to date.
Using reed beds for winter operation of wetland treatment system for wastewater
Authors: Hong Yin , Weiran Shen
Published: May 2018

If a Constructed Infiltration Wetland Treatment System (CIW-TS) with reed beds for wastewater could regularly operate and get the desired treatment efficiency during cold winter, the system would realize all-year-round operation. The technology presented is the result of a pilot scale treatment system in Tianjin, north China, one that successfully operated for two years. A characteristic of the technology is that the system could regularly operate under ice layers when the average temperature was lower than −4°C. Wastewater percolates through the thick soil layer in a horizontal direction. Effluent quality is better than secondary treatment level, e.g. BOD5<20 mg/l, SS<20 mg/l, TN<15 mg/l, TP<0.6 mg/l. A yearly hydraulic loading rate of 14-20 m is appropriate.
Nitrogen removal in constructed wetlands treating nitrified meat processing effluent
Authors: van Oostrom A. J.
Published: May 2018

The effect of plant and influent organic matter on nitrogen removal was investigated in four experimental surface-flow wetlands treating a nitrified meat processing effluent. Three wetlands contained a floating mat of the plant Glyceria maxima (and associated decaying plant litter). The fourth contained a simulated plant mat constructed of nylon fabric. The influent or 50% effluent recycle was irrigated over two of the plant-containing wetlands, while the other wetlands (and the one with 50% recycle) received influent at one end as per normal practice. Nitrogen removal in the planted wetlands during the final year of the study was about twice that in the wetland without plants, and averaged 46-49% (5.2-5.5 g N m−2 d−1) at a high average loading rate of 11.2 g N m−2 d−1. Summertime nitrogen removal reached 75% (approx. 9.5 g m−2 d−1). About 87% of the nitrogen removed by the planted wetlands was due to denitrification, with 13% due to accumulation in sediment and plant biomass. The plants (including plant litter) and influent organic matter were each responsible for about 50% of nitrogen removal, mainly through supplying organic carbon and creating anaerobic conditions for denitrification. Irrigation of wastewater over the plant mat did not enhance nitrogen removal.
The use of wetlands for the control of non-point source pollution
Authors: Raisin G. W. , Mitchell D. S.
Published: May 2018

There is increasing interest in the use of wetlands to intercept nutrients in diffuse run-off from rural catchments. However, the scientific basis for this strategy is far from secure. While research in several countries provides support for this approach, there is a general lack of rigorous data sets of nutrient balances showing the real effect of such wetlands on the quality of run-off emanating from rural catchments. Research being conducted on two natural and one constructed wetlands in south-eastern Australia will contribute to filling this gap.

In each of these three wetlands, volume of inflow and outflow is being measured at 15 minute intervals. Automatic water samplers connected to the flow measurement device are measured and are triggered to take samples at appropriate intervals during run-off events. All these water samples are analysed chemically and the total loads of selected chemicals entering and leaving a wetland are calculated for several storm events over the winter and spring period during 1993.

Results for Total Nitrogen and Total Phosphorus show that during winter there is a net release of these nutrients from the linear wetlands with greater flows resulting in greater flushing. However, in spring and early summer there was a net retention of nutrients in the wetlands despite similar hydrological loadings. These results were affected by the size of the wetland relative to the catchment (and therefore retention time), land use of the catchment, any intrusion of ground water and the nature of the wetland in terms of its shape and vegetation.
Treatment of primary-settled urban sewage in pilot-scale vertical flow wetland filters: comparison of four emergent macrophyte species over a 12 month period
Authors: Heritage Alan , Pistillo Pino , Sharma K. P. , Lantzke I. R.
Published: May 2018

The treatment of primary treated urban sewage by four emergent macrophytes has been compared over a twelve month period in separate gravel-based vertical flow constructed wetlands (300 litre interstitial volume). Nutrient removal in planted systems was greater than in the unplanted wetland especially for nitrogen and phosphorus and less so for BOD and suspended solids removal. The performance of most planted wetlands (especially Typha orientalis and Schoenoplectus validus) declined into autumn, particularly for nitrogen and phosphorus removal while a decline in plant ET was also observed. Baumea articulata, and to a lesser extent Cyperus involucratus, maintained high ET and nutrient assimilation throughout the trial period. As a consequence of the higher ET, dissolved solids (especially fixed salts) doubled in concentration during flow through wetlands planted with these two species, producing an effluent with a high sodium adsorption ratio and a reduced potential for re-use in irrigation.
Constructed wetland systems for water pollution control in North China
Authors: Li Xianfa , Jiang Chuncai
Published: May 2018

Constructed wetland systems are a low-cost, low-energy-consumption and effective technology for water pollution control used increasingly in recent years in China. In this paper, the land treatment systems in China are introduced, the constructed wetland systems in North China are detailed, and the integrated reed bed wetland-lagoon system, as an advanced constructed wetland system, is compared with other land treatment systems. Lastly, the authors elaborate their opinion on problem “wetlands occupy larger lands” and energetically advocate to develop this new land treatment technique in China.
Constructed wetlands for wastewater treatment in the Czech Republic - state of the art
Authors: Vymazal Jan
Published: May 2018

Constructed wetlands are an emerging technology in the Czech Republic. The inventory survey in 1993 revealed that since 1989 about 30 systems have been put into operation. The major reason for the inventory was to identify the main design criteria used in functional systems. It was found that all constructed wetlands are horizontal subsurface flow systems. The treatment area ranges between 20 and 6000 m2, population equivalent ranges between 4 and 1200. In most systems common reed (Phragmites australis) is used as a plant cover; other plants used are reed canarygrass (Phalaris arundinacea) and American mannagrass (Glyceria maxima). As filtration media sand, gravel and their mixtures are used. The treatment efficiency is high in terms of BOD5, COD and suspended solids while removal of phosphorus and nitrogen is lower.
Competition between nitrogen-fixing cyanobacteria during phosphorus-limited growth
Authors: De Nobel W. T. (Pim) , Staats N. , Mur L. R.
Published: May 2018

The phosphorus-limited growth of cultures of the nitrogen-fixing cyanobacteria Aphanizomenon and Anabaena was investigated. In conditions of nutrient and light excess Anabaena has a competitive advantage. The lower the light intensity conditions at which Aphanizomenon populations dominate are indicated for future study.
Refuse pollution of seas and oceans
Authors: Clunie W. F. , Hendricks D. W.
Published: May 2018

Refuse pollution of seas and oceans is not visible and the effects are difficult to assess. Attention to this problem has emerged seriously only since the 1980s. Marine scientists and environmental groups have been obtaining various data, however, and have indicated serious problems on a global scale to human values. Health, ecology, fisheries, commerce, recreation, etc., are areas of concern. The Black Sea may be as polluted as the world seas as a whole.

Refuse concentration of the oceans globally and of the Black Sea was estimated by the materials balance principle. A conceptual model, based upon the entropy principle, provides a means to estimate the energy of refuse cleanup. The model provides a rationale as to why the strategy for control must be containment of refuse.
Volatile fatty acids and sulfide in pressure mains
Authors: Hvitved-Jacobsen T. , Raunkjær K. , Nielsen P. H.
Published: May 2018

The main objective was to study the anaerobic transformation of organic matter and sulfide production during wastewater transportation. Emphasis was on the transformation of easily biodegradable organic matter in terms of volatile fatty acids (VFA). Samples from two intercepting pressure mains located in the Northern part of Jutland, Denmark, were taken.

The concentration of VFA in the wastewater varied considerably during day and night, being typically between 5 and 50 g/m3. A net production as well as a net removal of VFA was seen during transportation in the pressure mains probably depending on the quality and quantity of the organic matter. Typically 85% of the VFA was acetate and 10% propionate; the remainder was formate, n-butyrate and iso-butyrate. Observed sulfide production rates from the sewer biofilms were typically 0.05 and 0.005 g S/m2 h at 12 and 4 °C, respectively. A high sulfide production rate corresponded with a high VFA concentration. TOC removal was observed in the pressure mains.
The gully pot as a biochemical reactor
Authors: Morrison Gregory M. , Revitt D. Michael , Ellis J. Bryan
Published: May 2018

Roadside gully pots (catch basins) have been identified as potential sources that can make significant contributions to stormwater pollutant loadings. Between storm events the gully pot sediment and liquor undergo changes in composition as a result of biochemical reactions. Sediment maturation and acidic dissolution processes release pollutants from the contaminated chamber sediments and interstitial pore waters into the relatively clean gully pot liquor. Dissolved pollutant profiles for gully pot outflows therefore show substantial early contributions from gully pot liquor and interstitial waters reflecting microbial and geochemical degradation processes which act upon the trapped chamber sediments both during and between storm events.

The majority of dissolved organic carbon is washed out in the gully pot outflow in the early low flow stages, suggesting that the main contributing source is the supernatant gully pot liquor. Small additional releases coincide with, and indicate additional releases of, soluble organics from the interstitial waters as the basal sediments are disturbed. Conductivity changes show that dissolved inorganics also exhibit efficient removal during the low flow stages of storms, with the absence of delayed peaks indicating a negligible contribution from the settled gully pot sediments.

During storm events, low runoff rates produce marked decreases in pH levels from the initial gully pot liquor value of pH 6.0-7.1 to a value approaching typical rainfall levels (average rainfall pH = 4.1). This lowering of the pH indicates that the dissolved buffering agents initially present on the road surface and in the gully pot liquor have become depleted and exhaustion of dissolved Ca clearly illustrates this effect. Initial decreases in dissolved oxygen concentrations and redox potential are indicative of exposure of the reduced basal sediments as overlying supernatant liquor is washed out. A subsequent secondary decrease in redox potential, coinciding with increasing flows, is due to the additional release of reduced interstitial waters as the gully pot basal sediments are disturbed. Finally, dissolved oxygen levels return to normal as the oxygenated surface waters become predominant in the outflow waters.
Controlled dosing of nitrate for prevention of H2S in a sewer network and the effects on the subsequent treatment processes
Authors: Bentzen G. , Smith A. T. , Bennett D. , Webster N. J. , Reinholt F. , Sletholt E. , Hobson J.
Published: May 2018

A process for the elimination of septicity based on controlled addition of nitrate to sewer networks is developed. The process is registered as the NutrioxTM process. The work described in this paper gives the results of a full scale trial in the UK. The trial was set up and managed by Norsk Hydro and independently monitored and evaluated by the Water Research Centre Environmental Management (WRc). The results showed that dosing of nitrate was very effective for suppression of hydrogen sulphide in a rising main. During nitrate dosing the average level of hydrogen sulphide at the works inlet was 0.24 mg/l, with a daily variation within the range of 0-0.4 mg/l. Without nitrate addition the average background level of hydrogen sulphide was 4.2 mg/l, with a daily variation of 1-10 mg/l. The dosing was accomplished without significant breakthrough of nitrate to the treatment works. Dosing of nitrate resulted in an increased removal of soluble BOD across the rising main, but no significant change in total BOD or COD was registered at the treatment plant during the nitrate dosing. The nitrification process in the biological filters at the treatment plant was improved during the dosing period.
Dry and storm weather transport of coliforms and faecal streptococci in combined sewage
Authors: Ashley R. M. , Dabrowski W.
Published: May 2018

Combined sewage coliform bacteria are important as indicators of pathogenic microorganisms and of their possible discharge into the environment. Whilst specifying limits for viruses, most legislation recognises the difficulty of enumerating such organisms and also prescribes limits for coliforms. Despite the importance of these organisms, little is known about their numbers and behaviour in sewerage systems. A data collection programme is described which has monitored dry and wet weather sewage coliform bacteria and also sediment bacteria. These data are used to review recent UK recommendations for assessing bacteria numbers in storm discharges. It is concluded that relationships between bacteria numbers and other physical/chemical parameters may be developed during DWF, but are seasonally and catchment dependent. Extension of DWF measurements to predict storm bacteria may be possible with more data.
Is it possible to influence water temperature and quality in the river seine upstream of Paris in summer by managing the upstream reservoirs?
Authors: Malatre K. , Goose Ph.
Published: May 2018

There are four major reservoirs upstream of Paris, on the Seine, Aube, Marne and Yonne rivers. These reservoirs partially prevent flooding in winter and spring, and supply water in summer to maintain a minimum river flow. The quantitative and qualitative impact of summer water releases from dams on temperature and quality of downstream rivers has been assessed, thanks to a measurement survey conducted in 1990 and 1991 and use of simulation models.

Two types of reservoirs are distinguished:

– the Yonne reservoir, directly on the river, which is rather deep and can have a significant influence on the near downstream temperature, but hardly any just upstream of the Seine confluence

– the Seine, Aube and Marne reservoirs, bypassing the rivers, which are shallow and have a very moderate impact on downstream temperatures.

The study of an experimental water release on the Seine showed that for this second type of reservoir it is difficult to achieve considerable improvement in water quality in the downstream rivers by means of reservoir releases in summer, except locally in cases of significant pollution inputs. Among the ten parameters under study, conductivity and alkalinity were the only ones measured whose values could be affected by the dam release over a distance greater than 100 km downstream.
Modelling the flow of nitrogen and phosphorus in Europe: from loads to coastal seas
Authors: Beusen A. H. W. , Klepper O. , Meinardi C. R.
Published: May 2018

A model is described that aims at predicting surface water quality from N- and P-inputs on a European scale. The model combines a GIS-based approach to estimate loads, geohydrological data to define model structure and statistical techniques to estimate parameter values. The model starts with an inventory of sources of N and P: agriculture, wastewater and (for N) atmospheric deposition. Nitrogen flows are assumed to follow both surface- and groundwater flows, while for phosphorus only surface water flow is taken into account. A calibration of loss terms of N and P (assumed to be constants for the whole of Europe) by comparing total inputs to measured loads shows good agreement between observations and calculated river discharges. For the coastal seas of Europe concentrations are calculated by assuming conservative behaviour of N and P. Freshwater quality problems occur in western Europe with its intensive agriculture and high population density and locally in southern Europe where dilution is low due to low water discharge. In the marine environment the main problem areas are the Baltic and Black seas, with much lower impacts in the North and Adriatic Sea; in other coastal waters human impacts are essentially negligible.
Mass transfer coefficients for an autotrophic and a heterotrophic biofilm system
Authors: Horn H. , Hempel D. C.
Published: May 2018

To evaluate the mass transfer coefficients at the interface bulk/biofilm two biofilm systems with autotrophic and heterotrophic microbes were investigated with oxygen microelectrodes over a longterm period (1 year). To determine the transfer coefficient the oxygen profiles were simulated with a mass transfer model and compared with the measured substrate flux. The oxygen profiles at flow velocities >10 cm/s yielded concentration layers of about 100 μm and transfer coefficients > 10−4 m/s. These evaluated transfer coefficients were one magnitude higher than those known from hydrodynamics without biofilm reactions. Thus, the assumption, which determines the transfer coefficient as a quotient of the diffusion coefficient through the thickness of the laminar sublayer is oversimplified.
Study of nitrifying biofilms in submerged biofilters by experimental design methods
Authors: Fdz-Polanco F. , Méndez E. , Villaverde S.
Published: May 2018

The relative influence of influent ammonium concentration, pH, temperature, filter height and liquid and gas superficial velocities over the biofilm growth and activity in submerged nitrification biofilters has been experimentally studied. The goal is to quantify the relative contributions of the different control parameters over the biofilm growth and the specific activity of ammonia and nitrite oxidizer microorganisms.

The use of statistical tools like the experimental design methods, allows to characterize quantitatively the control parameters of the system and the levels providing the most favorable response of the system, in such a way that the noise factor influence is minimized. The experimental period is reduced eight times comparing to the traditional study of parameters influence.
Multicriteria methods in river basin planning – a case study
Authors: Anand Raj P.
Published: May 2018

A large number of multicriteria decision making (MCDM) methods have been proposed in the past and applied to water resources planning. The development and application of systems analysis techniques to assist decision makers in evaluating project alternatives having more than one objective in river basin planning is of recent origin.

In this paper an attempt is made to demonstrate the use of ELECTRE (ELimination and (Et) Choice Translating REality) I and ELECTRE-II techniques for water resources planning in one of the major river basins (Krishna river basin) of South India. The river basin consists of 8 reservoirs and a diversion work. Formulation of the problem is provided leading to an array of 27 alternative systems (different combinations of reservoirs with a minimum of three in each alternative) with 6 criteria related to: (i) irrigation, (ii) power production, (iii) drinking water, (iv) environmental quality; (v) floods and (vi) cost of the project. Out of the six criteria two, namely environmental quality and floods, are qualitative in nature. A set of best alternative systems with their partial ordering is obtained from ELECTRE-I, which forms the input for ELECTRE-II. Complete ordering of the reduced alternatives is achieved with ELECTRE-II. Sensitivity analysis shows that changing the weights assigned to each criterion has greater effect on the results than does changing the scales. However, neither effect is significant. Therefore it is recommended that ELECTRE-I be used for screening alternatives under consideration and ELECTRE-II for complete ordering of the reduced set.
Principles of designing secondary channels along the river rhine for the benefit of ecological restoration
Authors: Schropp M. H. I.
Published: May 2018

Secondary channels present a favourable opportunity for ecological restoration of the River Rhine and its branches. However, they have to be fitted into the landscape without affecting existing interests such as inland shipping and protection against flooding. Also the ecological targets have to be met with a minimum of human interference. In this article some design principles for secondary channels are presented in which these aspects are taken into account. To avoid silting up of the secondary channel it is recommended to prevent sediment from entering the channel at all. Flow velocities have to be below the threshold value for initiation of motion of sediment, but still high enough to satisfy the ecological targets. The secondary channel discharge is a function of the maximum allowable aggradation of the main channel. Discharge and flow velocities together determine the required cross-sectional area and thus the design value of the bank slopes. In order to have flowing water in the secondary channel all year round, the thalweg level is to be chosen on the basis of the water level frequency curve of the main channel.
Landuse – water quality modelling: a case study
Authors: Sekhar M. Chandra , Raj P. Anand
Published: May 2018

There can be no doubt that landuse profoundly affects the quality of water in streams, rivers, lakes and shallow aquifers. However, the task of finding specific cause - effect relationships between different landuses and Water Quality (WQ) is one of the most important ecological challenges of out times. At the present time, few tested procedures are available to study the landuse and Non-Point Source (NPS) pollution impacts on WQ. One methodology which offers considerable promise is the use of statistical analysis of landuse and WQ data from selected regions. Facilitating the systematic application of statistical procedures, in the present investigation, regression equations have been developed between landuse and WQ parameters. The results of the study indicated that landuse can account for up to 45% of the observed variation in mean nitrates, 39% of the observed variation in mean phosphates, 58% of the observed variation in mean fluoride concentration, 46% of the observed variation in mean COD concentrations and 72% of the observed variation in mean potassium concentrations.
Living with water: at the cross-roads of change
Authors: de Jong Joost , van Rooy Peter T. J. C. , Hosper S. Harry
Published: May 2018

Until the last two decades, the global perception of how to control our various water bodies was remarkably similar – water management was organised on a sectoral basis, as it always had been. It was only in the 1970s that the people actually responsible for implementing water management began to become aware of the serious implications of such an approach: water quality deterioration, desiccation and an alarming loss of the flora and fauna that characterised their local water environment. It was a growing awareness that led to the formation of the concept of integrated water management, a concept almost universally accepted today as the way forward. However, despite the fact that few dispute the validity of the concept, a number of obstacles remain before this theoretical agreement can be transformed into practical action. Three main bottlenecks stand in the way of implementation: institutional, communicational and socio-political. Whilst solutions to these are available, the key question still to be answered is whether society is really prepared to accept the consequent changes in the way we live that will result from putting the theory of integrated water management into practice. It was this issue that dominated the “Living with water” conference held in Amsterdam in September 1994. The following is a summary of the discussions held there and the various papers that were submitted.
Intermediary metabolism in fish with reference to output of end products of nitrogen and phosphorus
Authors: Cowey C. B.
Published: May 2018

The nutritional biochemistry of proteins and amino acids is briefly discussed; the dietary protein requirement (expressed as g/MJ digestible energy) is higher than that of a mammalian carnivore (the cat) which, in turn is higher than that of mammalian omnivores. The high protein requirement of the cat, relative to warm blooded omnivores is a requirement for non-specific N, that of salmonids is for both essential and for non-essential amino acids. Net retention of dietary N by fish is quantitatively similar to that of omnivorous birds and mammals (40-50%) so that up to 60% of assimilated N is excreted, largely in soluble form, and is available for eutrophication. It is difficult to see how this figure can be reduced by conventional dietary means. In mammals much of the loss of assimilated amino acids may be associated with protein turnover especially in muscle, quantitatively the most important tissue. Protein turnover in fish muscle is low, much of the protein synthesized there being retained and direct oxidation accounts for much of the loss of assimilated amino acids. The main P reservoir in fish tissues is flesh; few data are available on P turnover in fish under intensive cultivation. P flux in fish in natural ecosystems is low - less than 1% body P per day. Ecological studies indicate higher rates of P output in young, than in older, fish. However, under farming conditions about 90% of the feed is given to large fish (>100g). Of the P egested by salmonids under farming conditions about 30% is in particulate form and is probably not immediately available to plants: most of the soluble P (comprising about 60% of the total egested) appears to be biologically available to plants.
Dietary N and P levels, effluent water characteristics and performance in rainbow trout
Authors: Lanari D. , d'Agaro E. , Ballestrazzi R.
Published: May 2018

Two trials with rainbow trout have been performed to study the effect of dietary protein and phosphorus levels on growth rate and N and P balance. In the first trial, 702 rainbow trout (RT) (106.4 ± 1.26 g initial live weight) were fed for 86 days with three diets with the same ether extract (EE) content [20.45 % dry matter (DM)] but differing in protein and P content: [(36.7, 0.86 (A); 39.0, 0.97 (B) and 43.0%, 1.04% DM (C)]. Specific Growth Rate (SGR) and Feed Conversion Efficiency (FCE) were 0.94 and 1.31; 0.98 and 1.27; 1.05 and 1.17, respectively for treatments A, B and C. Feeding level significantly influenced SGR but not FCE. Nitrogen released into the environment was 46.0, 47.6 and 49.7 kg/t of fish produced for diets A, B and C respectively with no significant differences between treatments. P released into the environment was significantly lower with diet A (6.5 kg/t fish produced vs 7.5 and 7.6 with diets B and C). In the second trial, 360 RT (175 ± 2.5 g initial live weight) were fed 3 extruded diets at 0.94% live weight/d for 56 days. Each diet contained 28% EE and 39.4 (D), 42.0 (E) or 45.0 (F) % crude protein (CP). SGR and FCE increased significantly as dietary protein increased (1.03 and 0.94; 1.07 and 0.90; 1.15 and 0.84, respectively for treatments D, E and F, P < 0.05). N load in the effluents was not affected by dietary treatment (D: 29.9, E: 29.8 and F: 29.1 kg/t) whereas P load per t produced fell from diet E to F (D: 7.3, E: 6.7 and F: 5.9 kg, P < 0.05). The results of these experiments where food intake was restricted showed that the dietary level of N and P play an important role in determining the effluent load of these nutrients. At the same time, extrusion is a valid means of controlling N and P discharge, favourably improving growth rate, feed utilisation and gross protein retention.
Replacement of fish meal by plant proteins in diets for rainbow trout (oncorhynchus mykiss): effect of the quality of the fishmeal based control diets on digestibility and nutrient balances
Authors: Gomes Emídio F. , Rema P. , Gouveia A. , Teles A. Oliva
Published: May 2018

A great deal of attention has been paid to the replacement of the high levels of fishmeal present in commercial diets by alternative animal and vegetable protein sources. There are some contradictory data on the effects of partial or total replacement of dietary fishmeal especially regarding vegetable protein sources. The effect of technological treatments applied to the vegetable materials and the quality of the control diets are the reasons for these contradictory results. A ten week growth trial was conducted to study the effect of partial or total replacement of fishmeal by plant proteins in diets for rainbow trout. For this purpose, four practical diets were formulated: a fishmeal-based control diet, which included a brown fishmeal as the only protein source (diet C1); another diet where 5% of the brown fishmeal protein was replaced by a fishmeal protein concentrate (CPSP; diet C2); and two other diets where 50% (diet C50) and 100% (diet C100) of the fish meal protein was replaced by plant protein sources (soybean meal, fullfat soybean and corn gluten meal). The results of the growth trial showed that 50% of the fishmeal protein can be replaced by vegetable protein sources with no adverse effects on growth and feed utilization when diet C1 was used as control. However, using diet C2 as control, weight gains of trout fed the other diets were all significantly lower. Nitrogen and phosphorus balances were also estimated and results are discussed regarding the effect of diet quality on environmental impact.
Twenty-five years of waste water management in the Netherlands - an industrial view
Authors: Schut J.
Published: May 2018

This paper reflects, from an industrialist's perspective, on 25 years' operation of the Water Pollution Act in The Netherlands. The Act empowers Water Boards to implement national policy on water quality. These Boards may be regarded as a model for cooperation between the general public and industry, two partners that are both polluters and sufferers from pollution. Oxygen-consuming and heavy metal pollutants are considered as examples of the significant improvements achieved over the past quarter century.
A review of off-flavour tainting of drinking water and fish by pulp mill effluents
Authors: Kenefick S. L. , Low N. J. , Hrudey S. E. , Brownlee B. G.
Published: May 2018

Countries with major pulp and paper industries have experienced water or fish tainting episodes in the aquatic environment downstream from these discharges. Identification, control or prevention of such industry-specific odour events is not possible without a thorough understanding of the off-flavour compounds involved. A lengthy review of the available technical reports, government documents, books and periodical articles that document the current knowledge about water and fish tainting in the river basins of Northern Alberta has been published by Kenefick and Hrudey. The purpose of this full length review was to identify the incidence of or the potential for off-flavour tainting of fish and water by components discharged into the Peace, Athabasca, and Slave rivers from various sources. There is a relatively weak literature base directly related to taste and odour problems attributable to pulp mills in the Northern Alberta river basins. Consequently, discussions of other pulp mill related incidents of taste and odour problems throughout the world were also reviewed. There is little published information which addresses recent advances in pulping and bleaching technology and their effects on water and fish tainting. This paper provides an abbreviated version of the full review.
Two-stage UASB concept for treatment of domestic sewage including sludge stabilization process
Authors: Sayed S. K. I. , Fergala M. A. A.
Published: May 2018

A multi-target study was conducted to assess the feasibility of the UASB-reactor system for the anaerobic treatment of raw domestic sewage (low-strength complex wastewater; CODtot=200-700 mg/l and CODss=45-55% of CODtot) combined with sludge stabilization process under a moderate temperature of 18-20 °C.

The study has produced a design of a modified Three-Phase Separator (TPS) to control the sludge retention inside the UASB reactors as well as the determination of design parameters of the treatment process viz. the hydraulic retention time (HRT), the potential period of loading the UASB reactors and the most convenient digestion time required for advanced sludge stabilization. The study was performed in a Two-Stage Flocculent-Granular-Sludge UASB-reactor system. The first stage consisted of two identical UASB reactors seeded with flocculent sludge and operated alternately (i.e. one reactor was fed while the other was unfed for the stabilization of the sludge). The second stage consisted of one UASB reactor seeded with granular sludge and was operated continuously. The feed period and the corresponding feedless period of the first stage were two days.

The results study have shown that the removal efficiency of the COD increases considerably with the decrease of the HRT, as a treatment efficiency of 75% was achieved at HRT=10 h (8 h for Stage I and 2 h for Stage II), while the treatment efficiency was 84% at HRT=6 h (4 h for Stage I and 2 h for Stage II). In contrast to the above the extent of sludge stabilization (i.e. conversion into methane) for the first stage of the system was directly proportional to the HRT as 41% of the removed CODtot was converted into methane at HRT=8 h, the conversion ratio decreased to 28% at HRT=4 h.

For the granular sludge (the second stage of the system), the conversion ratio of the removed CODtot into methane was almost stable in the range of 17-20%. The percentages CODpaper-filtered of the CODtot were 85-90% and 92-97% for the effluents of the first and second stages respectively with the conclusion that the modified Three-Phase Separator (TPS) has a satisfactory operational potential.
Formation of 2,4,6-trichlorophenol and 2,4,6-trichloroanisole during treatment and distribution of drinking water
Authors: Karlsson S. , Kaugare S. , Grimvall A. , Borén H. , Sävenhed R.
Published: May 2018

Biomethylation of 2,4,6-trichlorophenol to the potent off-flavour compound 2,4,6-trichloroanisole has previously been found to cause taste and odour problems in drinking water. In the present study, both compounds were detected in seemingly unpolluted surface waters. However, the highest concentrations of 2,4,6-trichloroanisole in tap water were caused by the formation of 2,4,6-trichlorophenol during chlorine disinfection of drinking water and subsequent methylation of this compound in the distribution system. Analysis of samples from several sites in the investigated distribution systems showed that there was a substantial spatial and temporal variation of the concentration of both 2,4,6-trichloroanisole and its precursor.
Public health implications of waste water reuse for fish production
Authors: El-S. Easa M. , Shereif M. M. , Shaaban A. I. , Mancy K. H.
Published: May 2018

Public health and safety concerns have traditionally been the main reasons for resisting waste water reuse for fish farming. Potential adverse health effects in such applications could be avoided if the waste is sufficiently treated before reuse. In a full scale demonstration study in Suez, Egypt, about 400 m3/d of raw sewage were treated using a multi-compartment stabilization pond system, for a total residence time from 21-26 days. The treated effluent conformed to WHO guidelines and was used for rearing two types of local fish (tilapia and gray mullet). The produced fish were subjected to an extensive monitoring program. Bacteriological examination revealed that in all samples the fish muscles were free of bacterial contaminants. Nevertheless, low levels of Escherichia coli andAeromonas hydrophila, were isolated from the surface of the fish. Salmonellae, shigellae and staphylococcus aureus were absent from the surface of all the fish sampled. In addition, toxic metals (Pb, Cu, Zn, and Cd) were found to be at much lower levels than the international advisory limits for human consumption. It is concluded that fish reared in the treated effluent at Suez Experimental Station is (a) suitable for marketing for human consumption, and (b) it's quality is equal or better than fresh water fish in Egypt.