bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of SRT and DO on N2O reductase activity in an anoxic-oxic activated sludge system
Authors: Noda N. , Kaneko N. , Mikami M. , Kimochi Y. , Tsuneda S. , Hirata A. , Mizuochi M. , Inamori Y.
Published: May 2018

Nitrous oxide (N2O) is emitted from wastewater treatment processes, and is known to be a green house gas contributing to global warming. It is thus important to develop technology that can suppress N2O emission. The effects of sludge retention time (SRT) and dissolved oxygen (DO) on N2O emission in an anoxic-oxic activated sludge system were estimated. Moreover, the microbial community structure in the sludge, which plays an important role in N2O suppression, was clarified based on nitrous oxide reductase (nosZ) gene analysis by molecular biological techniques. The results showed that under low SRT conditions, nitrification efficiency was reduced and the N2O emission rate in the oxic reactors was increased. It was also observed that N2O emission was enhanced under low DO conditions, where the available oxygen is insufficient for nitrification. Moreover, molecular analysis revealed that the clones identified in this study were closely related to Ralstonia eutropha and Paracoccus denitrificans. The fact that the identified sequences are not closely related to known culturable denitrifier nosZ sequences indicates a substantial in situ diversity of denitrifiers contributing to N2O suppression, which are not reflected in the cultivatable fraction of the population. The further application of these new molecular techniques should serve to enhance our knowledge of the microbial community of denitrifying bacteria contributing to N2O suppression in wastewater treatment systems.
A system for on-site performance evaluation of small wastewater treatment plants according to the European procedure
Authors: Vasel J.L. , Jupsin H.
Published: May 2018

The new European standard project for performance evaluation of on-site systems (prEN 12566-3) provides a test procedure at user sites for individual on-site wastewater treatment. For each system, two plants of the same size have to be tested, one operating at 50% and the second one with a load greater than 75% of the nominal capacity. The test duration is one year and several stress tests are included in the program (holidays, bath water discharge and power breakdown). Flow based composite 24 h samples, on the influent and the effluent have to be used, with 30 day intervals for influent and 15 days for effluent. On each sample, the following measurements have to be done: BOD5 or COD, suspended solids, temperature, power consumption, daily flow. It appears that very few systems have been reported in the literature to follow up such facilities, especially describing how to sample at the inlet of on-site individual equipment. In order to obtain representative samples at the inlet and at the outlet of those on-site treatment systems, we have designed an original mobile sampler system. The whole system ensures the flow measurement and flow based sampling as well. In this paper, we present the different parts of the sampling system (pump, flowmeters, …), its validation and the results obtained at 5 user sites during the first 9 month period. Preliminary results are very interesting because they clearly demonstrate the need for an efficient on-site control of those user sites and for better legislation in this domain.
Waste stream utilisation for sustainable viticulture
Authors: Agnew R.H. , Mundy D.C. , Spiers T.M. , Greven M.M.
Published: May 2018

Field trials were established at four vineyards in January 1999 to evaluate the effects of four mulch mixtures on different soil and plant parameters. Mulches were made from wine industry and other commercially available plant and animal wastes. Soil, grape petioles, grape leaves and grape juice were analysed over three seasons. The mulches applied released considerable quantities of nutrients, which were available for use by the grapevines. Generally, the type of mulch used had little impact on the parameters that were measured and the greatest differences occurred between non-mulched and mulch treatments. Soil pH showed an increase at three of the four sites after application of mulch. Soil phosphorus increased moderately at one site and substantially at the other three sites in the first year and soil potassium levels increased dramatically at all sites in the first year. After the application of mulches in 1999 the petiole nitrate levels increased dramatically at all sites, however there were no differences in the second year. In the third year petiole nitrate levels were again high indicating that the differences between years was probably largely attributable to differences in rainfall received among the three seasons. Petiole potassium levels also increased after the application of mulch, however the increase was nowhere near as large as the increase in soil potassium. The use of mulch increased leaf nitrogen and potassium levels but not phosphorus levels. The use of mulch did increase juice potassium, however there was greater seasonal and site variation than variation due to the effect of mulch.
Treatment and valorisation of winery wastewater by a new biophysical process (ECCF®)
Authors: Colin T. , Bories A. , Sire Y. , Perrin R.
Published: May 2018

Taking account of the high specificity of the organic load of winery effluents, a new biophysical treatment using the stripping of ethanol combined with a final concentration by evaporation has been studied. Two options are proposed: full treatment and pre-treatment. The study of the composition of winery wastewater has shown the large, dominant part of ethanol in the organic load (75 to 99% of the COD). According to a linear correlation between COD and ethanol concentration, the determination of ethanol concentration can be used to estimate the organic load of winery wastewater. Full treatment by stripping and concentration at a pilot plant allows the separation of the wastewater into highly purified water (COD elimination>99%), a concentrated alcoholic solution usable as bio-fuel and a concentrated by-product. Stripping alone represents an advantageous pre-treatment of winery wastewater. The purification rate reaches 78 to 85% and ethanol is recovered. The process facilitates discharge into a sewage system in view of treatment with domestic effluents and can also improve the efficiency of overloaded or old purification plants.The economical approach of this method demonstrates its competitiveness in comparison with biological treatments: low energy consumed, no sludge.
Microflora evaluation of two agro-industrial effluents treated by the JACTO jet-loop type reactor system
Authors: Eusébio A. , Mateus M. , Baeta-Hall L. , Almeida-Vara E. , Duarte J.C.
Published: May 2018

Jet-loop type reactors developed in our group have been successfully used for biological treatment of winery and olive oil wastewaters. The objective of the present work was to study the influence of the reactor hydrodynamics, causing high shear stress applied on the nozzle and its influence on the composition of the microbial population. Winery and olive oil industry effluents were treated and analysed. Microbial consortia were enriched and selected under different bio-treatment conditions of the effluents. In the case of the winery wastewaters, the isolates identified belong to the genera of Pseudomonas and Bacillus. Saccharomyces cerevisiae was also present in the consortia but no filamentous fungi were detected. In the case of the olive oil wastewaters, Bacillus megaterium 2 was the predominant microorganism. It was not detected any type of fungi.
Degradation of wine industry wastewaters by photocatalytic advanced oxidation
Authors: Navarro P. , Sarasa J. , Sierra D. , Esteban S. , Ovelleiro J.L.
Published: May 2018

Wine industry wastewaters contain a high concentration of organic biodegradable compounds as well as a great amount of suspended solids. These waters are difficult to treat by conventional biological processes because they are seasonal and a great flow variation exists. Photocatalytic advanced oxidation is a promising technology for waters containing high amounts of organic matter. In this study we firstly investigated the application of H2O2 as oxidant combined with light (artificial or natural) in order to reduce the organic matter in samples from wine industry effluents. Secondly, we studied its combination with heterogeneous catalysts: titanium dioxide and clays containing iron minerals. The addition of photocatalysts to the system reduces the required H2O2 concentration. Although the H2O2/TiO2 system produces higher efficiencies, the H2O2/clays system requires a H2O2 dosage between three and six times lower.
Winery and distillery wastewater treatment by anaerobic digestion
Authors: Moletta R.
Published: May 2018

Anaerobic digestion is widely used for wastewater treatment, especially in the food industries. Generally after the anaerobic treatment there is an aerobic post-treatment in order to return the treated water to nature. Several technologies are applied for winery wastewater treatment. They are using free cells or flocs (anaerobic contact digesters, anaerobic sequencing batch reactors and anaerobic lagoons), anaerobic granules (Upflow Anaerobic Sludge Blanket – UASB), or biofilms on fixed support (anaerobic filter) or on mobile support as with the fluidised bed. Some technologies include two strategies, e.g. a sludge bed with anaerobic filter as in the hybrid digester.With winery wastewaters (as for vinasses from distilleries) the removal yield for anaerobic digestion is very high, up to 90–95% COD removal. The organic loads are between 5 and 15 kgCOD/m3 of digester/day. The biogas production is between 400 and 600 L per kg COD removed with 60 to 70% methane content. For anaerobic and aerobic post-treatment of vinasses in the Cognac region, REVICO company has 99.7% COD removal and the cost is 0.52 Euro/m3 of vinasses.
Uses of winery and distillery effluents in agriculture: characterisation of nutrient and hazardous components
Authors: Bustamante M.A. , Paredes C. , Moral R. , Moreno-Caselles J. , Pérez-Espinosa A. , Pérez-Murcia M.D.
Published: May 2018

Twenty-one samples of winery and distillery effluents were collected from different Spanish winery and distillery industries. Electrical conductivity, pH, redox potential, density, organic charge (chemical oxygen demand, biological oxygen demand, total, volatile and suspended solids, oxidisable organic C and polyphenols) and contents of plant nutrients and heavy metals were analysed. The aim of this work was to study the composition of these effluents and to find relationships which would make it possible to use easily determined parameters to estimate their composition. The winery wastewater (WW) and vinasse (V) showed an acidic pH, a high organic load and notable polyphenol, macronutrient, micronutrient and heavy metal contents. Some of these properties are not compatible with agricultural requirements; therefore, conditioning treatment of these liquid wastes is necessary to produce a safe, stable and easily manageable end product. Generally, in both effluent types, significant correlations were found between easily analysable parameters, such as suspended, volatile and total solids, pH, electrical conductivity, density and redox potential, and most of the parameters studied. The linear regression equations obtained permitted an immediate characterisation of the WW and V samples using these parameters.
Comparison of anaerobic treatment alternatives for brandy distillery process water
Authors: Chrobak R. , Ryder R.
Published: May 2018

This paper compares the conceptual design of anaerobic treatment alternatives for brandy distillery process water from the production of wine, brandy, high proof alcohol, and cleanup activities that will be land applied. The results of process water characterization and treatability testing are included. The wine industry's sustainable practices movement and recent tightening of the State of California requirements for land application of food and beverage processing wastewater, have forced facilities to reevaluate the characteristics, segregation options, and treatability requirements for recycling, reuse, or discharge of effluent to land treatment facilities. The treatment alternatives, results of characterization, and bench- and pilot-scale treatability testing for solids, organics, and nutrient removal using anaerobic and aerobic biological and physical-chemical treatment methods are presented. Based on test results and evaluation, we developed a conceptual design and cost estimates for process water treatment systems to remove solids, organics and nutrients that include energy recovery and produce effluent of improved quality for land application.
Effects of distillery vinasses on vineyard yield and quality in the D.O.C “Oltrepò Pavese Pinot Nero” – Lombardy, Italy
Authors: Tano F. , Valenti L. , Failla O. , Beltrame E.
Published: May 2018

In a fifteen year old vineyard of Pinot Noir at a density of 5000 vines per hectares, located in the DOC zone Oltrepò Pavese, the influence of growing doses of distillery vinasses on vegetative growth, leaf mineral levels, grape yield and quality was tested in a four year period. Doses of vinasses were computed to apply 0 (test), 50, 100, 150 kg N ha+1. Vinasses doses were factorially combined with three levels of urea (0, 50 and 100 kg N ha+1). In plots without vinasses supply, ureic nitrogen reduced the number of blind buds and increased the potential and actual bud fertility. The application of vinasses nitrogen had a similar result, even if ureic and vinasses nitrogen had no additive effects. The most profitable grape yield was obtained by application of 50 kg ha+1 of nitrogen either in urea or in vinasses form. Highest vinasses supply improved the ripening levels of grapes increasing sugars and reducing acidity of juice. Results clearly show the possibility to use vinasses for proper vineyard fertilisation.
Experimental analysis of the Hydrass flushing gate and field validation of flush propagation modelling
Authors: Bertrand-Krajewski J.-L. , Campisano A. , Creaco E. , Modica C.
Published: May 2018

As well known, a periodical cleansing of sewers results necessary in order to avoid or reduce many unpleasant consequences due to the presence of sediments, such as the solid re-suspension during rain events and the reduction of the channel flow capacity. For this purpose, different systems based on flushing techniques have been adopted in sewers. In the present paper, the results of an analysis of the hydraulics of a flushing device, the Hydrass gate, is presented. In particular, an experimental investigation on a scale model under steady conditions was carried out in order to determine the behaviour of the device during the flushing phase. Outflow relations were derived for the different outflow conditions. A numerical model was finally set up for testing the relations under unsteady conditions, using for validation the experimental data of a previous measurement campaign carried out in a sewer reach of the city of Lyon, France.
Wet-weather urban discharges: implications from adopting the revised European Directive concerning the quality of bathing water
Authors: David L.M. , Matos J.S
Published: May 2018

Wet weather urban discharges are responsible for bathing water contamination. The proposal for a revised EU Directive concerning the quality of bathing water imposes significantly more stringent requirements for the management of bathing water quality, with particularly important repercussions on beaches subjected to short-term pollution incidents. The paper reviews the aspects from EU legislation most directly related to the problem of wet-weather discharges, placing special emphasis on the recent revision process of the Directive on bathing water quality, and evaluates the benefits of some potential solutions based on continuous modelling of a combined sewer system. Increasing the sewer system storage capacity or the STP hydraulic capacity may substantially reduce the untreated discharge volumes, but spill frequency reductions under 2 to 3 spill days per bathing season will hardly be achieved. Results show the severe strains that local rainfall patterns would place on compliance with the Commission's proposal for a revised Directive and highlight the importance of the changes introduced in the amended proposal recently approved by the Council, making it less prescriptive if adequate measures are adopted to prevent bathers' exposure to short-term pollution incidents.
Nature and dynamic behaviour of organic surface layer deposits during dry weather
Authors: Oms C. , Gromaire M.C. , Chebbo G.
Published: May 2018

In-situ observations were performed at two different spatial and temporal scales, in order to get a better identification of the nature of the organic layer situated at the water–sediment interface, and which had previously been identified as major of combined sewer overflows organic loads. Its composition and its build up mechanisms during dry weather periods are presented. Results showed that the concept of dry weather accumulation and more generally the way organic sewer sediments are modelled needs to be reconsidered.
Aerobic transformations in sewer systems: are they relevant?
Authors: Flamink C. , Langeveld J. , Clemens F.
Published: May 2018

In-sewer transformation processes affect wastewater quality. Especially during dwf the transformation processes can exert a significant influence on wastewater quality. The transformation rates under aerobic conditions were estimated from an oxygen mass balance over a sewer reach. Oxygen probes were installed at the upstream and downstream end of the sewer reach. Moreover, 14 wastewater samples, taken at the downstream end of the sewer reach, were used to measure the oxygen uptake rate and the water quality parameters CODtotal, CODdissolved and ammonium. The results show that the rate of fluctuations in COD concentrations in sewer systems is an order of magnitude higher than the aerobic transformation rate. Consequently, it is concluded that the aerobic transformations in sewer systems are generally not relevant with respect to the influent fluctuations for Dutch wastewater systems. However, in situations with very long aerobic transport times, the aerobic conversions can be significant. An ASM1 based model concept for transformations in sewer systems was used to study the applicability of the model for Dutch sewer conditions. The difference between the measured and simulated values was rather low for the range of upstream dissolved oxygen and CODtotal, CODdissolved and CODsuspended levels. Therefore, it is concluded that the ASM1 based sewer model properly describes the changes in dissolved oxygen level in an aerobic sewer reach.
Effects of in-sewer processes: a stochastic model approach
Authors: Vollertsen J. , Nielsen A.H. , Yang W. , Hvitved-Jacobsen T.
Published: May 2018

Transformations of organic matter, nitrogen and sulfur in sewers can be simulated taking into account the relevant transformation and transport processes. One objective of such simulation is the assessment and management of hydrogen sulfide formation and corrosion. Sulfide is formed in the biofilms and sediments of the water phase, but corrosion occurs on the moist surfaces of the sewer gas phase. Consequently, both phases and the transport of volatile substances between these phases must be included. Furthermore, wastewater composition and transformations in sewers are complex and subject to high, natural variability. This paper presents the latest developments of the WATS model concept, allowing integrated aerobic, anoxic and anaerobic simulation of the water phase and of gas phase processes. The resulting model is complex and with high parameter variability. An example applying stochastic modeling shows how this complexity and variability can be taken into account.
Quantification of infiltration into sewers based on time series of pollutant loads
Authors: Kracht O. , Gujer W.
Published: May 2018

We introduce the concepts of a novel approach that allows for the quantification of infiltrating non-polluted waters by a combined analysis of time series of pollutant concentrations and discharged wastewater volume. The methodology is based on the use of automated sensors for the recording of the pollutant concentrations. This provides time series in a high temporal resolution that are suitable for a detailed data analysis and discussion on the underlying assumptions. The procedure is demonstrated on two examples from recent measurement campaigns in Switzerland.
SHARON process evaluated for improved wastewater treatment plant nitrogen effluent quality
Authors: van Kempen R. , ten Have C.C.R. , Meijer S.C.F. , Mulder J.W. , Duin J.O.J. , Uijterlinde C.A. , van Loosdrecht M.C.M.
Published: May 2018

New stricter nitrogen effluent standards and increasing influent loads require existing wastewater treatment plans (WWTPs) to extend or optimize. At WWTPs with limited aeration capacity, limited denitrification capacity or shortage of aerobic sludge age, implementation of SHARON to improve nitrogen effluent quality can be a solution. SHARON is a compact, sustainable and cost-effective biological process for treatment of nitrogen-rich rejection waters. At WWTP Rotterdam-Dokhaven and WWTP Utrecht a SHARON has been in operation for several years. For both WWTPs the effect of SHARON on the nitrogen effluent quality has been evaluated. WWTP Rotterdam-Dokhaven has limited aeration capacity. By implementation of SHARON, the ammonia load of the effluent was reduced by 50%. WWTP Utrecht had limited denitrification capacity. The implementation of SHARON improved the effluent nitrate load by 40%. The overall TN removal efficiency increased from 65% to over 75% and strict nitrogen effluents standards (TN = 10 mg N/l) could be reached. Through modelling and supported by full scale practice it has been shown that by implementation of SHARON in combination with enhanced influent pre-treatment, the aerobic sludge age can be extended to maintain total nitrogen removal at lower temperatures.
Upgrading of the STP Uithoorn: treatment of nutrient rich wastewater from horticulture
Authors: Piekema P. , Neef R.
Published: May 2018

The STP Uithoorn will be upgraded to accommodate the treatment of wastewater from a growing population and to meet more stringent nutrient discharge limits in 2006. In 2003 a system choice and preliminary design was made for the upgrading. A special feature is the nutrient rich wastewater flow from the rapidly developing horticulture in the area. Since the future loads from horticulture are highly uncertain, flexibility of the STP after upgrading is an important issue. A three stage system was selected: improved physical-chemical primary treatment, secondary treatment by activated sludge, and tertiary treatment by denitrifying filters. In this way an important part of the existing infrastructure can be reused, and flexibility is assured by constructing the tertiary treatment in modules and by providing a wide range of operational control possibilities. In this paper the process of system choice and selection of type of tertiary treatment are described, as well as the optimisation of the existing treatment. In order to determine the feasibility of allowing a high loading rate on the existing secondary clarifiers, a two-dimensional hydraulic model of the clarification process was used.
Climate change and effects on water quality: a first impression
Authors: Senhorst H.A.J. , Zwolsman J.J.G.
Published: May 2018

A number of possible relationships between climate change and water quality of Dutch surface waters have been investigated and an indicative quantification of the impact of climate change on water quality has been established. The analysis focused on water quality during periods of low flow and extreme heat, which are assumed to increase in frequency and intensity due to climate change. The results indicate that the impact of climate change on water quality cannot be generalised and should be assessed on a case by case basis. However, the impact on extreme situations (floods and droughts) seems to be largest, whilst water quality under average discharge conditions appears to be relatively unchanged.
Uncertainty in predicting riverbed erosion caused by urban stormwater discharge
Authors: Daebel H. , Gujer W.
Published: May 2018

Ecologically based criteria require an integrated modeling approach. Due to the complexity of the system, the stochastic nature of loads, and the model abstractions, many uncertainties are involved. In this study, a simple integrated model is applied, which Swiss engineers employ to assess the impact of urban stormwater discharges on riverbed stability. In the course of a case study, an uncertainty analysis is carried out focusing on parameter uncertainties. The underlying context of the uncertainties is evaluated, and a variance-based sensitivity analysis is presented estimating the local uncertainty contribution of each parameter. The results reveal that the largest contributions stem from the model components describing the natural system. An experimental design is proposed that manages to reduce the output uncertainty significantly. Finally, we discuss the benefits of following the proposed procedure.
Improved formulations for rapid erosion of diverse solids in combined sewers
Authors: McIlhatton T.D. , Ashley R.M. , Tait S.J.
Published: May 2018

For more than a decade, research carried out in Scotland has investigated the movement of sediment in sewers and the associated pollutant release. Pollution by discharges from combined sewer overflows can adversely affect watercourses, particularly those in urban areas. Solids and dissolved contaminants, many derived from in-sewer deposits during a storm event, can be especially significant. This phenomenon can occur during events known as ‘foul flushes’. In combined sewers these typically occur in the initial period of storm flows, when the concentration of suspended sediments and other pollutants is significantly higher than at other times. It has become apparent that much of the suspended load originates from solids eroded from the bed. The ‘near bed solids’ which are re-entrained into the flow, together with solids eroded from the bulk bed, account for large changes in the suspended sediment concentration under time varying flow conditions. This paper describes some of the methods employed to investigate the solids eroding in combined sewers during peak flow events. The work examined the potential for sediment re-suspension under high flow conditions both in the laboratory and in the field.
Integrated modelling for the evaluation of infiltration effects
Authors: Schulz N. , Baur R. , Krebs P.
Published: May 2018

The objective of the present study is the estimation of the potential benefits of sewer pipe rehabilitation for the performance of the drainage system and the wastewater treatment plant (WWTP) as well as for the receiving water quality. The relation of sewer system status and the infiltration rate is assessed based on statistical analysis of 470 km of CCTV (Closed Circuit Television) inspected sewers of the city of Dresden. The potential reduction of infiltration rates and the consequent performance improvements of the urban wastewater system are simulated as a function of rehabilitation activities in the network. The integrated model is applied to an artificial system with input from a real sewer network. In this paper, the general design of the integrated model and its data requirements are presented. For an exemplary study, the consequences of the simulations are discussed with respect to the prioritisation of rehabilitation activities in the network.
Flooding in the future – predicting climate change, risks and responses in urban areas
Authors: Ashley R.M. , Balmforth D.J. , Saul A.J. , Blanskby J.D.
Published: May 2018

Engineering infrastructure is provided at high cost and is expected to have a useful operational life of decades. However, it is clear that the future is uncertain. Traditional approaches to designing and operating urban storm drainage assets have relied on past performance of natural systems and the ability to extrapolate this performance, together with that of the assets across the usable lifetime. Whether or not climate change is going to significantly alter future weather patterns in Europe, it is clear that it is now incumbent on designers and operators of storm drainage systems to prepare for greater uncertainty in the effectiveness of storm drainage systems. A recent UK Government study considered the potential effects of climate and socio-economic change in the UK in terms of four future scenarios and what the implications are for the performance of existing storm drainage facilities. In this paper the modelling that was undertaken to try to quantify the changes in risk, together with the effectiveness of responses in managing that risk, are described. It shows that flood risks may increase by a factor of almost 30 times and that traditional engineering measures alone are unlikely to be able to provide protection.
SIPSON – Simulation of Interaction between Pipe flow and Surface Overland flow in Networks
Authors: Djordjević S. , Prodanović D. , Maksimović Č. , Ivetić M. , Savić D.
Published: May 2018

The new simulation model, named SIPSON, based on the Preissmann finite difference method and the conjugate gradient method, is presented in the paper. This model simulates conditions when the hydraulic capacity of a sewer system is exceeded, pipe flow is pressurized, the water flows out from the piped system to the streets, and the inlets cannot capture all the runoff. In the mathematical model, buried structures and pipelines, together with surface channels, make a horizontally and vertically looped network involving a complex interaction of flows. In this paper, special internal boundary conditions related to equivalent inlets are discussed. Procedures are described for the simulation of manhole cover loss, basement flooding, the representation of street geometry, and the distribution of runoff hydrographs between surface and underground networks. All these procedures are built into the simulation model. Relevant issues are illustrated on a set of examples, focusing on specific parameters and comparison with field measurements of flooding of the Motilal ki Chal catchment (Indore, India). Satisfactory agreement of observed and simulated hydrographs and maximum surface flooding levels is obtained. It is concluded that the presented approach is an improvement compared to the standard “virtual reservoir” approach commonly applied in most of the models.
Uncertainty and precaution in environmental management
Authors: Krayer von Krauss M. , van Asselt M.B.A. , Henze M. , Ravetz J. , Beck M.B.
Published: May 2018

In this paper, two different visions of the relationship between science and policy are contrasted with one another: the “modern” vision and the “precautionary” vision. Conditions which must apply in order to invoke the Precautionary Principle are presented, as are some of the main challenges posed by the principle. The following central question remains: If scientific certainty cannot be provided, what may then justify regulatory interventions, and what degree of intervention is justifiable? The notion of “quality of information” is explored, and it is emphasized that there can be no absolute definition of good or bad quality. Collective judgments of quality are only possible through deliberation on the characteristics of the information, and on the relevance of the information to the policy context. Reference to a relative criterion therefore seems inevitable and legal complexities are to be expected. Uncertainty is presented as a multi-dimensional concept, reaching far beyond the conventional statistical interpretation of the concept. Of critical importance is the development of methods for assessing qualitative categories of uncertainty. Model quality assessment should observe the following rationale: identify a model that is suited to the purpose, yet bears some reasonable resemblance to the “real” phenomena. In this context, “purpose” relates to the policy and societal contexts in which the assessment results are to be used. It is therefore increasingly agreed that judgment of the quality of assessments necessarily involves the participation of non-modellers and non-scientists. A challenging final question is: How to use uncertainty information in policy contexts? More research is required in order to answer this question.
Late lessons from early warnings: towards precaution and realism in research and policy
Authors: Gee D. , Krayer von Krauss M.P.
Published: May 2018

This paper focuses on the evidentiary aspects of the precautionary principle. Three points are highlighted: (i) the difference between association and causation; (ii) how the strength of scientific evidence can be considered; and (iii) the reasons why regulatory regimes tend to err in the direction of false negatives rather than false positives. The point is made that because obtaining evidence of causation can take many decades of research, the precautionary principle can be invoked to justify action when evidence of causation is not available, but there is good scientific evidence of an association between exposures and impacts. It is argued that the appropriate level of proof is context dependent, as “appropriateness” is based on value judgements about the acceptability of the costs, about the distribution of the costs, and about the consequences of being wrong. A complementary approach to evaluating the strength of scientific evidence is to focus on the level of uncertainty. If decision makers are made aware of the limitations of the knowledge base, they can compensate by adopting measures aimed at providing early warnings of un-anticipated effects and mitigating their impacts. The point is made that it is often disregarded that the Bradford Hill criteria for evaluating evidence are asymmetrical, in that the applicability of a criterion increases the strength of evidence on the presence of an effect, but the inapplicability of a criterion does not increase the strength of evidence on the absence of an effect. The paper discusses the reason why there are so many examples of regulatory “false negatives” as opposed to “false positives”. Two main reasons are put forward: (i) the methodological bias within the health and environmental sciences; and (ii) the dominance within decision-making of short term economic and political interests. Sixteen features of methods and culture in the environmental and health sciences are presented. Of these, only three features tend to generate “false positives”. It is concluded that although the different features of scientific methods and culture produce robust science, they can lead to poor regulatory decisions on hazard prevention.
Precautionary information-generation in scienceand the law
Authors: Cranor C.
Published: May 2018

An information-generation system should be part of precautionary approaches to protecting the public's health and the environment. Such a system would include inventories or surveys of health and the environment, monitoring of them, as well as scoping out or scouting for threats or other harmful things that could occur and providing sentinels to try to identify threats before they materialize. I, then, suggest some ways in which such strategies could be adopted in science and the law as part of a precautionary approach. Doing more to generate information in an anticipatory way will assist implementation of the precautionary principle and help remove some of the uncertainty in environmental and public health protections.
The optimisation approach of ALARA in nuclear practice: an early application of the Precautionary Principle. Scientific uncertainty versus legal uncertainty
Authors: Lierman S. , Veuchelen L.
Published: May 2018

The late health effects of exposure to low doses of ionising radiation are subject to scientific controversy: one view finds threats of high cancer incidence exaggerated, while the other view thinks the effects are underestimated. Both views have good scientific arguments in favour of them. Since the nuclear field, both industry and medicine have had to deal with this controversy for many decades. One can argue that the optimisation approach to keep the effective doses as low as reasonably achievable, taking economic and social factors into account (ALARA), is a precautionary approach. However, because of these stochastic effects, no scientific proof can be provided. This paper explores how ALARA and the Precautionary Principle are influential in the legal field and in particular in tort law, because liability should be a strong incentive for safer behaviour. This so-called “deterrence effect” of liability seems to evaporate in today's technical and highly complex society, in particular when dealing with the late health effects of low doses of ionising radiation. Two main issues will be dealt with in the paper:How are the health risks attributable to “low doses” of radiation regulated in nuclear law and what lessons can be learned from the field of radiation protection?What does ALARA have to inform the discussion of the Precautionary Principle and vice-versa, in particular, as far as legal sanctions and liability are concerned?It will be shown that the Precautionary Principle has not yet been sufficiently implemented into nuclear law.
A guidance for assessing and communicating uncertainties
Authors: Janssen P.H.M. , Petersen A.C. , van der Sluijs J.P. , Risbey J.S. , Ravetz J.R.
Published: May 2018

In the daily practice of science for policy, as experienced by governmental agencies which inform the policy and the public on the state and outlook of the environment, there is a pressing need for guidance in assessing and communicating uncertainties. This need extends beyond the quantitative assessment of uncertainties in model results, and focuses on the entire process of environmental assessment, running from problem framing towards reporting the results of the study. Using the Netherlands Environmental Assessment Agency (RIVM/MNP) as a case, the development, structure and content of such a guidance system is highlighted. Conditions for a successful implementation of the guidance system are discussed, and some prospects for future work are outlined.
An integrated methodology for recording uncertainties about environmental data
Authors: Brown J.D. , Heuvelink G.B. , Refsgaard J.C.
Published: May 2018

Understanding the limitations of environmental data is essential both for managing environmental systems effectively and for encouraging the responsible use of scientific research when knowledge is limited and priorities are varied. Using a combination of quantitative and qualitative techniques for assessing probabilities, and acknowledging the importance of scenarios where probabilities cannot be determined, an integrated methodology is presented for handling uncertainties about environmental data. The methodology is based on a fourfold distinction between the empirical quality of data (and the ancillary information, such as ‘scale’, required to interpret this), the sources of uncertainty in data, the ‘fitness for use’ of the data, and the quality or ‘goodness’ of an uncertainty model.
Model uncertainty – parameter uncertainty versus conceptual models
Authors: Højberg A.L. , Refsgaard J.C.
Published: May 2018

Uncertainties in model structures have been recognised often to be the main source of uncertainty in predictive model simulations. Despite this knowledge, uncertainty studies are traditionally limited to a single deterministic model and the uncertainty addressed by a parameter uncertainty study. The extent to which a parameter uncertainty study may encompass model structure errors in a groundwater model is studied in a case study. Three groundwater models were constructed on the basis of three different hydrogeological interpretations. Each of the models was calibrated inversely against groundwater heads and streamflows. A parameter uncertainty analysis was carried out for each of the three conceptual models by Monte Carlo simulations. A comparison of the predictive uncertainties for the three conceptual models showed large differences between the uncertainty intervals. Most discrepancies were observed for data types not used in the model calibration. Thus uncertainties in the conceptual models become of increasing importance when predictive simulations consider data types that are extrapolates from the data types used for calibration.
Impact of morphological parameters on water quality variables of a regulated lowland river
Authors: Lindenschmidt K.-E. , Poser K. , Rode M.
Published: May 2018

An efficient method to investigate which morphological changes have greatest impact on the water quality is to carry out a computer modelling exercise. In this study, three models, a hydrodynamic (DYNHYD), a eutrophication model (EUTRO), and a sediment and micro-pollutant transport model (TOXI), were coupled together in the High Level Architecture (HLA) platform. DYNHYD dynamically simulates the propagation of a wave through a river reach one-dimensionally by solving the full dynamic wave equation. Important parameters that describe the river morphology are the roughness coefficient and the weir discharge coefficient. EUTRO simulates the phytoplankton-nutrient dynamics in water bodies with variables and parameters that regulate the process in this cycle. Examples of some of the more important parameters are the oxygen reaeration, phytoplankton growth or nitrification rates. TOXI was implemented to simulate the transport of sediments and heavy metals in which the most important transformation process of the metals was sorption. It is the aim of this study to see the effect that hydrodynamic parameters such as weir discharge and roughness coefficients have on water quality constituents, such as chlorophyll-a, dissolved oxygen and levels of ammonium and dissolved zinc.
NMR methods for in-situ biofilm metabolism studies: spatial and temporal resolved measurements
Authors: Majors P.D. , McLean J.S. , Fredrickson J.K. , Wind R.A.
Published: May 2018

We are developing novel nuclear magnetic resonance (NMR) microscopy, spectroscopy and combined NMR/optical techniques for the study of biofilms under known, controlled growth conditions. Objectives include: time and depth-resolved metabolite concentrations with isotropic spatial resolution on the order of 10 microns, metabolic pathways and flux rates, mass transport and ultimately their correlation with gene expression by optical microscopy in biofilms. We describe the implementation of ex-situ grown biofilms to improve growth environment control and NMR analysis. In-situ NMR depth resolved metabolite profiling techniques are introduced and demonstrated for a Shewanella oneidensis strain MR-1 biofilm. Finally, initial combined confocal fluorescence and magnetic resonance images are shown for a GFP-labeled Shewanella biofilm. These methods are equally applicable to other biofilm systems of interest; thus they may provide a significant contribution toward the understanding of adherent cell metabolism.
Effect of exopolysaccharides on the adsorption of metal ions by Pseudomonas sp. CU-1
Authors: Lau T.C. , Wu X.A. , Chua H. , Qian P.Y. , Wong P.K.
Published: May 2018

Pseudomonas sp. CU-1, which was isolated from an interfacial biofilm of a sludge sample collected from an electroplating company, had a relatively high ability to adsorb Cu2 +  in solution. The bacterium grown in broth culture produced a large amount of capsular exopolymers mainly consisting of polysaccharides. The exopolysaccharides (EPS) were partially purified. The adsorption isotherm experiments showed that cells and EPS of Pseudomonas sp. CU-1 had similar Q0 and b for the dye, Janus Green, and Cu2+. The adsorption of Cu2 +  by cells could be monitored by the amount of dye displaced, due to the binding of metal ions onto the cell surface. The order of adsorption ability of metal ions and dye displacement by metal ion of the bacterium was: Cu2 + > Cd2 + > Zn2 + > Ni2 + . The results of the dye displacement by metal ions binding onto the surfaces of cells, EPS-removed cells, and EPS suggest that EPS produced by Pseudomonas sp. CU-1 plays an important role in preventing metal ions in the surrounding environment from contact with the bacterial cells. The possible role of the metal ion adsorption by the EPS of this biofilm bacterium was discussed.
Evaluating heterotrophic growth in a nitrifying biofilm reactor using fluorescence in situ hybridization and mathematical modeling
Authors: Nogueira R. , Elenter D. , Brito A. , Melo L.F. , Wagner M. , Morgenroth E.
Published: May 2018

The objective of this study was to evaluate the significance of heterotrophic growth in nitrifying biofilm reactors fed only with ammonium as an energy source. The diversity, abundance and spatial distribution of nitrifying bacteria were studied using a combination of molecular tools and mathematical modeling, in two biofilm reactors operated with different hydraulic retention times. The composition and distribution of nitrifying consortia in biofilms were quantified by fluorescence in situ hybridization (FISH) with rRNA-targeted oligonucleotide probes combined with confocal laser scanning microscopy (CLSM) and digital image analysis. Autotrophic and heterotrophic biofilm fractions determined by FISH were compared to the output from a multispecies model that incorporates soluble microbial products (SMP) production/consumption. In reactor R1 (short retention time) nearly 100% of the total bacteria could be identified as either ammonia- or nitrite-oxidizing bacteria by quantitative FISH analyses, while in reactor R2 (long retention time) the identification rate was only 73%, with the rest probably consisting of heterotrophs. Mathematical simulations were performed to evaluate the influence of the hydraulic retention time (HRT), biofilm thickness, and substrate utilization associated SMP production on the growth of heterotrophic bacteria. The model predicts that low HRTs resulted in a lower availability of SMPs leading to purely autotrophic biofilms. These model predictions are consistent with experimental observations. At HRTs that are about an order of magnitude larger than the reciprocal of the net maximum growth rate the majority of the active biomass will grow suspended in the bulk phase rather than in the biofilm.
Eco-physiology of autotrophic nitrifying biofilms
Authors: Okabe S. , Kindaichi T. , Nakamura Y. , Ito T.
Published: May 2018

Microautoradiography combined with fluorescent in situ hybridization (MAR-FISH), a powerful tool for linking physiology with identification of individual cells, was applied to investigate microbial interactions between nitrifying bacteria and coexisting heterotrophic bacteria in an autotrophic nitrifying biofilm community fed with only ammonia as the sole energy source and bicarbonate as the sole carbon source. First, nitrifying bacteria were radiolabeled by culturing the biofilm samples with [14C]bicarbonate for 6 h, and then the transfer of radioactivity from nitrifying bacteria to heterotrophic bacteria was monitored by using MAR-FISH. MAR-FISH revealed that the heterotrophic bacterial community was composed of bacteria that were phylogenetically and metabolically diverse. We could obtain direct evidence that organic matter derived from nitrifiers was subsequently utilized by mainly filamentous bacteria belonging to the Chloroflexi (green non-sulfur bacteria) group or CFB group in the biofilm, which was clearly visualized by MAR-FISH at single cell resolution for the first time. On the other hand, the members of the α- and γ-Proteobacteria were specialized to utilize low-molecular-weight organic matter. This community represents functionally integrated units that assure maximum access to and utilization of metabolites of nitrifiers.