bluuebunny/crossref_metadata_2025 huggingface dataset:
Significance of denitrifying enzyme dynamics in biological nitrogen removal processes: a simulation study
Authors: Lee D.-U. , Casasus-Zambrana A. , Hamilton R. , Svoronos S. , Lee S.-I. , Koopman B.
Published: May 2018

Activated Sludge Model No.1 (ASM1) was extended to include the enzyme kinetics of denitrifying bacteria switching between oxygen and nitrate as electron acceptors. The extended ASM1 (eASM1) model was applied to two different periodic process configurations, fed-batch and Biodenipho, commonly used for nitrogen removal from wastewater. Predictions of optimal unaerated volume fraction (UVF) by eASM1 were similar to those by ASM1 for both the fed-batch and Biodenipho processes. However, eASM1 predicted substantially longer optimal cycle lengths than ASM1 for both processes. Predictions of optimal UVF and cycle length for the Biodenipho process by eASM1 were closer to current operational values for the University of Florida Biodenipho process than predictions by ASM1.
Fluorescence in situ hybridization analysis of nitrifiers in piggery wastewater treatment reactors
Authors: Kim D.J. , Kim T.K. , Choi E.J. , Park W.C. , Kim T.H. , Ahn D.H. , Yuan Z. , Blackall L. , Keller J.
Published: May 2018

Fluorescence in situ hybridization (FISH) was performed to analyze the nitrifying microbial communities in an activated sludge reactor (ASR) and a fixed biofilm reactor (FBR) for piggery wastewater treatment. Heterotrophic oxidation and nitrification were occurring simultaneously in the ASR and the COD and nitrification efficiencies depend on the loads. In the FBR nitrification efficiency also depends on ammonium load to the reactor and nitrite was accumulated when free ammonia concentration was higher than 0.2 mg NH3-N/L. FISH analysis showed that ammonia-oxidizing bacteria (NSO1225) and denitrifying bacteria (RRP1088) were less abundant than other bacteria (EUB338) in ASR. Further analysis on nitrifying bacteria in the FBR showed that Nitrosomonas species (NSM156) and Nitrospira species (NSR1156) were the dominant ammonia-oxidizing and nitrite-oxidizing bacteria, respectively, in the piggery wastewater nitrification system.
Sludge management of small water and wastewater treatment plants
Authors: Nowak O. , Kuehn V. , Zessner M.
Published: May 2018

“Disposal or reuse?” is the big question in respect to sewage and water sludges. This question is even more decisive for small plants, because the achievement of the advanced treatment necessary for disposal is much more difficult in small units than in big ones. The paper discusses this question with main focus on small WWTPs and gives a short overview of the specifics of sludge treatment in small units as well as of outlets for sludge from water treatment plants. In general, small WWTPs do not have a better sludge quality than larger ones, but the economic pressure to realise reuse is higher on them than on large plants.
Developments in the application of chemical technologies to wastewater treatment
Authors: Tünay O.
Published: May 2018

Increasing demand for high degree of treatment as well as existence of highly resistant organics in wastewaters such as micropollutants has caused wider and ever increasing use of chemical treatment processes. In this paper developments in the chemical treatment as applied to mostly industrial wastewater in the last two decades are summarized and discussed. Two purely chemical means of treatment, chemical oxidation and chemical precipitation were considered and proven and widely used methods of treatment based on these principles were delineated. The review covers theoretical development, application areas and application bases. A brief evaluation of the state of development, advantages, drawbacks and need for further research was given for the processes reviewed.
Model-based evaluation of COD influence on a partial nitrification-Anammox biofilm (CANON) process
Authors: Hao X.-D. , van Loosdrecht M.C.M.
Published: May 2018

A model evaluating COD influence on a partial nitrification-Anammox biofilm process is integrated on the basis of heterotrophic growth as described in ASM3, combined with a previously published model for the CANON process. This integrated model can simulate the activities of heterotrophs and autotrophs involved in a biofilm, and interactions between COD oxidation, denitrification, nitrification and Anammox can be evaluated. Simulations indicate that COD in the influent has no important influence on the trends in the partial nitrification-Anammox biofilm process. Besides full COD removal, a total nitrogen removal efficiency of about 90% can be expected for stable biofilm systems. Furthermore, Anammox is a major contributor to the total nitrogen removal in stable biofilm systems and conventional denitrification only takes a share of <20% in the total nitrogen removal.
High nitrification rate at low pH in a fluidized bed reactor with chalk as the biofilm carrier
Authors: Tarre S. , Beliavski M. , Denekamp N. , Gieseke A. , de Beer D. , Green M.
Published: May 2018

A typical steady state bulk pH of about 5 was established in a nitrifying fluidized bed with chalk as the only buffer agent. In spite of the low pH, high rate nitrification was observed with the nitrification kinetic parameters in the chalk reactor similar to those of biological reactors operating at pH>7. Various methods were used to determine the reasons for high rate nitrification at such low pH including (i) determination of bacterial species, (ii) microsensor measurements in the biofilm, and (iii) comparison of nitrification performance at low pH with a non-chalk fluidized bed reactor. Fluorescence in situ hybridization (FISH) using existing 16S rRNA-targeted oligonucleotide probes showed common nitrifying bacteria in the low pH chalk reactor. The prevalent nitrifying bacteria were identified in the Nitrosomonas oligotropha, Nitrosomonas europeae/eutropha, Nitrosospira and Nitrospira related groups, all well known nitrifiers. Microelectrode measurements showed that the pH in the biofilm was low and similar to that of the bulk pH. Finally, reactor performance using a non-chalk biofilm carrier (sintered glass) with the same bacterial inoculum also showed high rate nitrification below pH 5. The results suggest that inhibition of nitrification at low pH is highly overestimated.
Greywater treatment by constructed wetlands in combination with TiO2-based photocatalytic oxidation for suburban and rural areas without sewer system
Authors: Li Z. , Gulyas H. , Jahn M. , Gajurel D.R. , Otterpohl R.
Published: May 2018

In this study greywater treatment through constructed wetlands and subsequently through TiO2-based photocatalytic oxidation was investigated. Through constructed wetlands treatment the organic substances have been reduced greatly. For further removal of organic substances and pathogens, a TiO2-based photocatalytic oxidation process was used subsequently. The results showed that the treated greywater through constructed wetlands and subsequent through TiO2-based photocatalytic oxidation with short irradiation time (3 hours irradiation time) met the requirements of European bathing water quality easily. Therefore, the greywater treated with the processes combination can directly be reused for non-potable purposes. Moreover, since residual organic substances through TiO2-based photocatalytic oxidation with long irradiation time can be eliminated almost totally, it is also possible that treated greywater is used for groundwater recharge as a drinking water resource.
Biofilm modeling with AQUASIM
Authors: Wanner O. , Morgenroth E.
Published: May 2018

AQUASIM is a computer program for the identification and simulation of aquatic systems. The program includes a one-dimensional multisubstrate and multispecies biofilm model and represents a suitable tool for biofilm simulation. The program can be used to calculate substrate removal in biofilm reactors for any user specified microbial system. One-dimensional spatial profiles of substrates and microbial species in the biofilm can be predicted. The program also calculates the development of the biofilm thickness and of the substrates and microbial species in the biofilm and in the bulk fluid over time. Detachment and attachment of microbial cells at the biofilm surface and in the biofilm interior can be considered, and simulations of sloughing events can be performed. Furthermore, AQUASIM allows pseudo two-dimensional modeling of plug flow biofilm reactors by a series of biofilm reactor compartments. The most significant limitation of the model is that it only considers spatial gradients of substrates and microbial species in the biofilm in the direction perpendicular to the substratum.
Comparing biofilm models for a single species biofilm system
Authors: Morgenroth E. , Eberl H.J. , van Loosdrecht M.C.M. , Noguera D.R. , Pizarro G.E. , Picioreanu C. , Rittmann B.E. , Schwarz A.O. , Wanner O.
Published: May 2018

A benchmark problem was defined to evaluate the performance of different mathematical biofilm models. The biofilm consisted of heterotrophic bacteria degrading organic substrate and oxygen. Mathematical models tested ranged from simple analytical to multidimensional numerical models. For simple and more or less flat biofilms it was shown that analytical biofilm models provide very similar results compared to more complex numerical solutions. When considering a heterogeneous biofilm morphology it was shown that the effect of an increased external mass transfer resistance was much more significant compared to the effect of an increased surface area inside the biofilm.
Sand filter clogging by septic tank effluent
Authors: Spychala M. , Blazejewski R.
Published: May 2018

The aim of this study was to characterise conditions and factors affecting fine sand clogging by septic tank effluent on the basis of physical modelling. The physical model consisted of 12 sand columns dosed with sewage from one household (5 persons), preliminary treated in a septic tank. Hydraulic loadings of the sand filters were equal to 82 mm/d. The mean discharge from sand columns, measured as the effluent volume collected during 10 minutes, decreased significantly over the experiment period from 34 cm3/min in August 2000 to 20 cm3/min in August 2001 at the same temperature of about 20°C. First the columns clogged almost completely after 480 days in December 2001, however six columns had remained unclogged till the end of the experiment (March 2002). The temperature had a significant impact on hydraulic conductivity. A vertical distribution of accumulated mass and biomass was investigated in partly clogged sand. Microscopic survey of the clogging layer showed a presence of live micro-organisms, residuals of dead micro-organisms, particularly pieces of small animal armour and many fibres. These particles accelerated the accumulation of solids in the upper clogging layer. The study indicated that temperature impact on the filter hydraulic conductivity was more significant for biological activity, than for sewage viscosity.
Two-dimensional cellular automaton model for mixed-culture biofilm
Authors: Pizarro G.E. , Garcia C. , Moreno R. , Sepulveda M. E.
Published: May 2018

Structural and microbial heterogeneity occurs in almost any type of biofilm system. General approaches for the design of biofilm systems consider biofilms as homogeneous and of constant thickness. In order to improve the design of biofilms systems, models need to incorporate structural heterogeneity and the effect of inert microbial mass. We have improved a 2D biofilm model based on cellular automata (CA) and used it to simulate multidimensional biofilms with active and inert biomass including a self-organizing development. Results indicate that the presence of inert biomass within biofilm structures does not change considerably the substrate flux into the biofilm because the active biomass is located at the surface of the biofilm. Long-term simulations revealed that although the biofilm system is highly heterogeneous and the microstructure is continuously changing, the biofilm reaches a dynamic steady-state with prediction of biofilm thickness and substrate flux stabilizing on a delimited range.
Effect of high salinity on anaerobic treatment of low strength effluents
Authors: Ozalp G. , Gomec C.Y. , Ozturk I. , Gonuldinc S. , Altinbas M.
Published: May 2018

In anaerobic treatment, it is obligatory to know the effect of potentially inhibitory compounds due to the fact that methane formation may retard severely and may proceed slower than organic acid production. One of the most important inhibitory substances in anaerobic treatment is high salinity. In many cases, the main collectors of a municipal sewer system should have been built in the coastal zone and below the ground water level due to the available topography of wastewater catchments area, which is carrying the risk of seawater infiltration. Besides, one of the most convenient methods for leachate control is to treat landfill leachates with domestic wastewaters in the central municipal wastewater treatment plants such as in Istanbul. Thus, the nitrogen load of the treatment plants increase significantly. In this study, the effects of high salinity and ammonium nitrogen levels on mesophilic anaerobic tretament processes were investigated. In the first part of the study, high salinity effect on anaerobic treatment was investigated by feeding synthetic wastewater containing high salinity between 0.15%–1.5% ratios. In the second part of the study, the simultaneous effect of high salinity and ammonia (1.5% salinity+1,000 mg NH3/l) was examined by a lab-scale Upflow Anaerobic Sludge Bed Reactor (UASBR). Results indicated no significant inhibition in both cases and effective COD removals (89%) and total biogas productions having methane content of 84% could be achieved.
Experimental study on carbon removal in biological aerated filters
Authors: Farabegoli G. , Carucci A. , Gandolfo G. , Rolle E. , Viotti P.
Published: May 2018

The aim of the present work was to evaluate the performance of a pilot-scale BAF in terms of removal of organic matter and suspended solids to obtain a highly polished effluent. The first part of the research was the evaluation of the optimal filter media for a full scale BAF. Mechanical and biological tests were performed over four materials: glass, plastic, pozzolan and expanded clay (Arlita) and the results obtained showed that the plastic spheres and the Arlita particles were the optimal materials for both the mechanical and biological requirements. Hence, a down-flow pilot scale BAF was set up in the laboratory to treat a synthetic medium. As filter media first plastic spheres and then Arlita spheres were used. Carbon removal studies were carried out at several influent COD concentrations, specific removal efficiency and COD profiles along the height of the filter were determined and used to analyze the process. Validation and calibration of a mathematical model formulated for carbon removal, were also performed by using the experimental data obtained. The results showed that this system allows us to achieve the more strict limits on final effluent.
A new low-cost biofilm carrier for the treatment of municipal wastewater in a moving bed reactor
Authors: Orantes J.C. , González-Martínez S.
Published: May 2018

The Moving Bed Biofilm Reactor has proven to be an efficient system in wastewater treatment and has become a viable solution for small treatment plants. The main objective of this research was to analyse the performance of a moving bed reactor using low-cost local material when fed with municipal wastewater. A pilot reactor with a total volume of 900 litres was built and it was fed continuously with municipal wastewater. The operation of the system was adjusted to six different organic loading rates. The biofilm carrier was polyethylene tubing with internal diameter of 1.1 cm, cut into pieces of 1.2 cm. The tested material offered a specific surface area of 590 m2/m3. Air was provided with a fine-bubble diffuser. The main results show that the reactor performance was stable and predictable. The COD removal confidently behaves according to a general hyperbolic kinetic equation. The maximal total COD removal attained was 81%. Nitrification was observed only for organic loads with values under 5.7 gCOD/m2·d. Good adherence of the microorganisms was observed for the applied organic loading rates. After several months of operation, the material showed no signs of abrasion or deformation. The sludge production behaved linearly with the organic load reaching 979 gTSS/d with the highest organic load of 35.7 gCOD/m2·d. The amount of microorganisms attached to the carrier increased with the organic load tending to an asymptotical maximal value of 17.3 g/m2 (as dry solids). Mean cellular retention times from 2.0 to 23.1 days were determined.
Effects of feeding strategies on the performance of an anaerobic discontinuous reactor containing immobilized biomass with circulation system for liquid-phase mixing
Authors: Orra A.A. , Ratusznei S.M. , Rodrigues J.A.D. , Foresti E. , Zaiat M.
Published: May 2018

Data on the influence of feeding strategy on the performance of a fed-batch anaerobic sequencing reactor containing biomass immobilized on polyurethane foam and subjected to liquid phase circulation are presented and discussed. Six-hour cycles, temperature of 30°C and circulation flow rate of 6 L/h were used. During each cycle 890 mL of synthetic domestic wastewater, with organic matter concentration of 500 mgCOD/L were fed to the reactor. The feeding strategies were implemented using fill times of 6 min (batch mode), 60, 120, 240 (fed-batch/batch mode) and 360 min (fed-batch mode). The system attained high efficiency and stability for all the operating conditions, and the substrate removal efficiency based on filtered samples presented a slight decrease from 85% to 81% when fill time was increased from 6 min to 360 min. A model considering a first-order kinetic equation was fitted to the experimental data. The apparent kinetic parameters for both batch and fed-batch phases were estimated, thus permitting evaluation of the influence of the feeding strategy on the reactor performance. The current system may be considered flexible in terms of the operating conditions it is subjected to.
Performance of a hybrid SBR with fixed bed and suspended growth
Authors: Kim H. , Rhu D. , Hwang H. , Choi E.
Published: May 2018

A hybrid SBR system combined with fixed bed (media) and suspended growth zones was developed to improve both nitrogen and phosphorus removal. About 27% of the tank volume was filled with clay media to make a fixed bed in this system, and additional air was applied under the bed to wash the microbes from the media during the oxic stage to prevent the bed from clogging. This hybrid SBR system could eliminate the backwashing requirement for SBBR (sequencing batch biofilm reactor). This system showed a stable nitrification even at low temperature and shock load conditions. The specific reaction rates indicated the fixed bed zone had higher microbial activities for nitrification and denitrification, while the suspended growth zone had higher microbial activities for phosphorus release and uptake. In addition, the use of external sludge storage also increased both phosphorus and nitrogen removal. The effluent COD, nitrogen and phosphorus concentrations were respectively less than 15, 10.5 and 0.6 mg/L with weak sewage of 230 mg/L COD, 35 mg/L TKN and 5.3 mg/L TP.
Behaviour of biofilm systems under varying hydrodynamic conditions
Authors: León Ohl A. , Horn H. , Hempel D.C.
Published: May 2018

Heterotrophic biofilms were cultivated in long-term experiments in biofilm tube reactors. During the biofilm cultivation the substrate loading of glucose was kept constant while the hydrodynamic conditions were changed stepwise. To describe the behaviour of the biofilm structure under these varying flow conditions the mass transfer and transport at the bulk/biofilm interface and inside the biofilm was investigated with oxygen microelectrodes. Furthermore, the biofilm density was used to describe the biofilm compactness before and after the change of the hydrodynamic condition.

The obtained results show that the biofilm density and also the substrate flux decreased with decreasing flow velocity in the bulk phase. Additionally the slope of the oxygen concentration profiles decreased and the thickness of the concentration boundary layer increased. On the other hand, increasing the flow velocity in the bulk phase led both to a higher biofilm density and a higher maximum substrate flux. The biofilm surface became more homogenous and the thickness of the concentration boundary layer decreased. The time for adaptation of the biofilm structure after changing the hydrodynamic conditions ranged between 1 and 3 weeks.
Transition of bacterial spatial organization in a biofilm monitored by FISH and subsequent image analysis
Authors: Aoi Y. , Tsuneda S. , Hirata A.
Published: May 2018

The dynamic transition of bacterial community structure in a biofilm was monitored by the fluorescence in situ hybridization (FISH) technique and subsequent image analysis. Heterotrophic bacteria that had occupied the outer layer were gradually decreased whereas ammonia-oxidizing bacteria (AOB) gradually increased their growth activity and extended their existence area to the outer layer of the biofilm through the gradual reduction of the C/N ratio. The spatial organization of AOB in the biofilm dynamically changed responding to the environmental conditions such as pH fluctuation and lack of dissolved oxygen (DO) and had great influence on the nitrification activity. The accumulation of nitrite was observed at lower DO concentration, which might be due to the property that nitrite-oxidizing bacteria (NOB) possess of higher Km values for oxygen than AOB.
Comparison of intermittently aerated continuous and batch biofilm reactor in nutrient removal
Authors: Altinbaş Ufuk , Öztürk Izzet
Published: May 2018

Removal efficiency of TOC ranged between 86–89% in an intermittently aerated reactor. High efficiency in TKN removal and nitrification was found at lower applied load or longer retention time such as 2 days. TKN removal and nitrification efficiency was found to be 17–96% and 35–99% respectively. Through examination and comparison of the removal efficiencies, the stability of nitrification/denitrification and the biological phosphorus removal it was found that the sequencing batch feeding system gave a higher performance in total nitrogen and phosphorus removals. In the SBR reactor, nitrogen removal efficiency was mainly controlled by organic loading. Nitrification efficiency ranged between 31–56%. Nearly complete denitrification was observed in the sequencing batch reactor.
Consumer managed co-operative - a solution for progressing wastewater management in rural areas
Authors: Mattila H. , Santala E. , Aho J.
Published: May 2018

In Finland the question of appropriate wastewater treatment in rural areas has become very prominent during the last years. The new Environmental Protection Act stipulates that wastewaters must be treated to the extent that they cannot have a negative impact on nature. The Ministry of the Environment is currently preparing a decree specifying the requirements. The draft of the decree proposes that on-site treatment units should decrease the BOD load by 90, total phosphorus load by 85 and total nitrogen load by 40 per cent. To meet the new requirements, the old systems that include septic tanks only need more efficient wastewater treatment methods. Whatever technical solution is selected, the house owner must pay for it. At the moment, even the septic tanks are emptied and maintained irregularly. More sophisticated wastewater treatment methods definitely need more maintenance, which cannot be made the sole duty of the house owners. One potential organisational alternative for managing wastewater treatment in rural areas is the co-operative. Finland has one such pioneering co-operative formed for on-site sanitation. Varsinais-Suomi Water Services Co-operative provides the house owner with professional assistance in wastewater treatment at a reasonable cost. Suvisaari Water Services Co-operative is another new organisation selling sewerage services to its members. But its technology is different: this co-operative operates an LPS-sewerage system instead of on-site treatment.
On the use of crushed shells of apricot stones as the upper layer in dual media filters
Authors: Aksoğan S. , Baştürk A. , Yüksel E. , Akgiray Ö
Published: May 2018

The use of crushed shells of apricot stones instead of anthracite coal in dual-media filters is investigated. Turbidity removal efficiencies were measured for several filtration rates in dual media filters composed of shells of apricot stones above silica sand and anthracite coal above silica sand. Backwash (fluidization) experiments were carried out using sieved fractions of crushed shells of apricot stones to establish curves of expansion versus backwash velocity at 25°C. Such curves can be used in the design of filters employing this material. It is believed that the use of such a locally available and cheaper alternative filter medium would be of interest in many small water and wastewater treatment systems around the world.
The role of soil chemistry in wine grape quality and sustainable soil management in vineyards
Authors: Mackenzie D.E. , Christy A.G.
Published: May 2018

This study aimed to establish if there is any evidence that soil mineralogical and/or chemical composition influence the composition and quality of wine grapes. In the initial phase of the study, soils and grapes were sampled in two riesling vineyards in South Australia. Soils were analysed for a wide range of total major and trace elements; soil cation extracts and grape juices were analysed for 27 trace elements by ICP-MS and ICP-AES. The results show that grape juice properties such as Baumé and titratable acidity (TA) are clearly correlated with several plant-available trace elements in the soil. Most notable of these are Ca, Sr, Ba, Pb and Si. Soil clay content also plays a (lesser) role. The cations Ca, Sr, Ba and Pb are closely similar to one another in their relationships to Baumé and TA, strongly indicating that the correlations are real. It is evident from our results that soil cation chemistry does indeed have an influence on wine grape composition. Such knowledge has the potential to be used in better tailoring grape varieties to soils, and in managing – or modifying – soils for optimum viticultural results and better wines in a more sustainable way.
Activated sludge wastewater treatment plants optimisation to face pollution overloads during grape harvest periods
Authors: Beck C. , Prades G. , Sadowski A.-G.
Published: May 2018

The principal objective of our study was to optimise a municipal activated sludge wastewater treatment plant (WWTP) to face high organic flows due to viticulture effluents inputs. Treatment file optimization consisted in testing different treatment lines, changing the number and volume of biological basins and clarifiers, with or without a buffer basin upstream, with a view to achieving a better reduction of COD. The actual WWTP biological stage is composed of two aerated basins whose total volume is 1365 m3. The studied cases are successively, the installation of a single basin of 1365 m3, then of several basins whose total volume remains constant and equal to 1365 m3. Another case was also considered, that of an aerated basin followed by a first clarifier and then, by another aerated basin and a second clarifier. All scenarios presented below were evaluated, for standard dry weather conditions and for high organic load conditions, as encountered during the grape harvest period. The method used was to carry out various simulations, using numerical modelling, and to compare the impact of different process line scenarios and management strategies on the activated sludge WWTP efficiencies.
Treatment of mixed municipal and winery wastewaters in a conventional activated sludge process: a case study
Authors: Brucculeri M. , Bolzonella D. , Battistoni P. , Cecchi F.
Published: May 2018

The possibility of co-treating municipal and winery wastewaters in a conventional activated sludge process was studied at full scale. The wastewater treatment plant considered in this paper operated an extended-oxidation process during vintage (four month per year) and a pre-denitrification/oxidation process during the rest of the year. The experimentation showed that good performances, in terms of COD and nitrogen removal, could be obtained in both cases: 90% and 60%, for COD and nitrogen removal, respectively. Thanks to the high solid retention times applied to the system (up to 48 days) the waste activated sludge production was low (0.20 kgMLVSS/kgCODremoved) and respiration was the main process for carbon removal. Nitrification was always satisfactory while the behaviour of the denitrification process during vintage was not totally understood and further studies are going on.
Physico-chemical treatment for the depuration of wine distillery wastewaters (vinasses)
Authors: de Heredia J. Beltran , Dominguez J.R. , Partido E.
Published: May 2018

In the present work, an integrated Fenton-coagulation/flocculation process was applied for the depuration of wine distillery wastewaters, commonly known as "vinasses". This study evaluates the Fenton process (H2O2/Fe2+), involving oxidation – in a first stage and coagulation/flocculation (using Ca(OH)2 as base-precipitant) – in a second stage for the removal of chemical oxygen demand (COD). The experimental variables studied were the dosages of hydrogen peroxide and iron salts, the molar ratio [H2O2]o:[Fe2+]o, the effluent dilution and the manner in which the reagents were added (splitting the reagent dose of hydrogen peroxide and ferrous salt into different fractions). The optimal operating conditions of the integrated process were: [H2O2]o=0.5 mol/L using an optimal concentration ratio [H2O2]o:[Fe2+]o=15 mol/mol. Under these conditions, the COD removal was 74%.
High rate anaerobic thermophilic technologies for distillery wastewater treatment
Authors: Pérez-García M. , Romero-García L.I. , Rodríguez-Cano R. , Sales-Márquez D.
Published: May 2018

In this paper, performance of two high rate technologies, upflow anaerobic fixed-film reactor and fluidized bed laboratory-scale, treating distillery wastewater (wine vinasses ) at anaerobic thermophilic conditions have been compared. The results obtained show that the stationary packed bed, with a corrugated plastic support, operated under stable conditions at organic loading rates (OLR0) around 20 kgCOD/m3/d, gives maximal total CODr of 76% at OLR0 of 6.29 kgCOD/m3/d; the fluidized bed reactor, operated on open pore sintered-glass media, gives total CODr of 96% at OLR0 of 5.88 kgCOD/m3/d. The anaerobic fluidized bed technology is more effective than the upflow anaerobic fixed-film technology due, fundamentally, to this technology favouring the transport of microbial cells from the bulk to the surface and enhancing the contact between the microorganism-substrate phases. In this sense, the stationary packed bed technology is adequate for the treatment of easily biodegradable wastewater, or for the cases where elevated percentages of CODr removal are not required, while the fluidized bed technology is especially suitable for treatment of hazardous wastes with recalcitrant compositions.
Performance-costs evaluation for urban storm drainage
Authors: Baptista M. , Barraud S. , Alfakih E. , Nascimento N. , Fernandes W. , Moura P. , Castro L.
Published: May 2018

The design process of urban stormwater systems incorporating BMPs involves more complexity unlike the design of classic drainage systems for which just the technique of pipes is likely to be used. This paper presents a simple decision aid methodology and an associated software (AvDren) concerning urban stormwater systems, devoted to the evaluation and the comparison of drainage scenarios using BMPs according to different technical, sanitary, social environmental and economical aspects. This kind of tool is particularly interesting so as to help the decision makers to select the appropriate alternative and to plan the investments especially for developing countries, with important sanitary problems and severe budget restrictions.
Simulation of sulfide buildup in wastewater and atmosphere of sewer networks
Authors: Nielsen A.H. , Yongsiri C. , Hvitved-Jacobsen T. , Vollertsen J.
Published: May 2018

A model concept for prediction of sulfide buildup in sewer networks is presented. The model concept is an extension to – and a further development of – the WATS model (Wastewater Aerobic-anaerobic Transformations in Sewers), which has been developed by Hvitved-Jacobsen and co-workers at Aalborg University. In addition to the sulfur cycle, the WATS model simulates changes in dissolved oxygen and carbon fractions of different biodegradability. The sulfur cycle was introduced via six processes: 1. sulfide production taking place in the biofilm covering the permanently wetted sewer walls; 2. biological sulfide oxidation in the permanently wetted biofilm; 3. chemical and biological sulfide oxidation in the water phase; 4. sulfide precipitation with metals present in the wastewater; 5. emission of hydrogen sulfide to the sewer atmosphere and 6. adsorption and oxidation of hydrogen sulfide on the moist sewer walls where concrete corrosion may take place.
Measurement of infiltration rates in urban sewer systems by use of oxygen isotopes
Authors: De Bénédittis J. , Bertrand-Krajewski J.-L.
Published: May 2018

The paper presents the principle of a method to measure infiltration rates in sewer systems based on the use of oxygen isotopes and its application in Lyon (France). In the urban area of Lyon, significant differences in δ18O that can reach 3‰ are observed between the oxygen isotopic compositions of groundwater originating from Rhone, Saone and from their associated alluvial aquifers. Drinking water supplying Lyon results mainly from pumping in the Rhone alluvial aquifer. Therefore, in some areas, the difference of isotopic composition between wastewater resulting from the consumption of drinking water and local groundwater can be used to measure infiltration in sewer systems. The application in the catchment of Ecully shows that the infiltration flow rate presents strong fluctuations at an hourly scale: it varies between 15 and 40 m3/h. This variability could be explained by non-constant discharges of pumping and by variations of the water level in the sewer.
Boosting nitrification with the BABE technology
Authors: Berends D.H.J.G. , Salem S. , van der Roest H.F. , van Loosdrecht M.C.M.
Published: May 2018

Over the past years there has been a growing interest for compact, simple, low cost and robust technologies to upgrade wastewater treatment plants for nitrogen removal. The BABE (Bio Augmentation Batch Enhanced) technology is such a new concept. This patented system for biological treatment of sludge liquor – the effluent produced from digested sludge – uses a new principle, boosting the nitrifying bacteria in a side stream in such a way that the activated sludge in the main process is augmented. This augmentation increases the nitrification capacity of the wastewater treatment plant (wwtp). Experiments on a practical scale have demonstrated the effective and stable operation of the BABE technology. Model studies supported by the results of the full-scale tests showed that the technology can be applied in several situations, i.e. 1) introducing nitrification at high loaded wwtps; 2) enhancing nitrification at wwtps with incomplete nitrification; 3) enlarging denitrification at wwtps with complete nitrification. Most likely this year a full-scale application will be realized in the Netherlands at a wwtp with insufficient nitrification throughout the year.
Surface models for coupled modelling of runoff and sewer flow in urban areas
Authors: Ettrich N. , Steiner K. , Thomas M. , Rothe R.
Published: May 2018

Traditional methods fail for the purpose of simulating the complete flow process in urban areas as a consequence of heavy rainfall and as required by the European Standard EN-752 since the bi-directional coupling between sewer and surface is not properly handled. The new methodology, developed in the EUREKA-project RisUrSim, solves this problem by carrying out the runoff on the basis of shallow water equations solved on high-resolution surface grids. Exchange nodes between the sewer and the surface, like inlets and manholes, are located in the computational grid and water leaving the sewer in case of surcharge is further distributed on the surface. Dense topographical information is needed to build a model suitable for hydrodynamic runoff calculations; in urban areas, in addition, many line-shaped elements like houses, curbs, etc. guide the runoff of water and require polygonal input. Airborne data collection methods offer a great chance to economically gather densely sampled input data.
Future increase in harmful algal blooms in the North Sea due to climate change
Authors: Peperzak L.
Published: May 2018

In temperate seas such as the North Sea harmful (toxic) algal blooms will probably increase as a result of climate change. This conclusion was reached after investigating the projected effect of climate change for the year 2100 in Dutch coastal waters (4°C temperature rise and increased water column stratification) on the growth rates of six harmful and two non-harmful phytoplankton species. Micro algae form the basis of the marine food chain. However, toxin-producing species may seriously disrupt the food web and lead to fish kills and human intoxication. Two species with estimated doubled growth rates in 2100, F. japonica and C. antiqua, entered Europe via ship's ballast water or shellfish imports. This stresses the need to legally regulate such invasion routes in order to prevent the import of novel species. Future toxic phytoplankton blooms may further devaluate ecosystem deliverables such as fish production or recreational use. This devaluation can be estimated by monetary value assessments that are needed in cost-benefit analyses for policy guidance. The lack of understanding of future climate, ecosystem functioning and its response to climate change calls for a scientific effort to improve our knowledge on present day coastal ecosystem functioning and its resilience.
Climate change and drinking water production in The Netherlands: a flexible approach
Authors: Ramaker T.A.B. , Meuleman A.F.M. , Bernhardi L. , Cirkel G.
Published: May 2018

Climate change increases water system dynamics through temperature changes, changes in precipitation patterns, evaporation, water quality and water storage in ice packs. Water system dependent economical stakeholders, such as drinking water companies in The Netherlands, have to cope with consequences of climate change, e.g. floods and water shortages in river systems, upconing brackish ground water, salt water intrusion, increasing peak demands and microbiological activity. In the past decades, however, both water systems and drinking water production have become more and more inflexible; water systems have been heavily regulated and the drinking water supply has grown into an inflexible, but cheap and reliable, system. Flexibility and adaptivity are solutions to overcome climate change related consequences. Flexible adaptive strategies for drinking water production comprise new sources for drinking water production, application of storage concepts in the short term, and a redesign of large centralised systems, including flexible treatment plants, in the long term. Transition to flexible concepts will take decades because investment depreciation periods of assets are long. This implies that long-term strategies within an indicated time path have to be developed. These strategies must be based on thorough knowledge of current assets to seize opportunities for change.
Modeling stochastic load variations in sewer systems
Authors: Ort C. , Schaffner C. , Giger W. , Gujer W.
Published: May 2018

In wastewater treatment and environmental risk assessments increasing attention is paid to the fate of micropollutants. These are time-consuming, expensive and difficult to detect and quantify. If a substance's load or concentration is subject to high dynamic fluctuations, it is demanding to take representative samples, especially when the “variation” is unknown. Therefore, we developed a concept to model stochastic load variations in sewer systems. We gathered readily available information from existing databases (population and consumption data) and combined it with the characteristics of household activities and appliances. We succeeded in predicting realistic short-term variations of benzotriazole (contained in dishwasher detergents) and validated them with a high-frequency measuring campaign. Benzotriazole stands as an example for other household chemicals, which cannot be measured so easily. All required information used within this case study is also available for other substances and catchments. This allows the forecast of stochastic load variations for many chemical compounds of interest. It helps to plan measuring campaigns, to estimate discharged loads from combined sewer overflows and to have a characteristic input for modeling purposes.
Dispersion coefficients of sewers from tracer experiments
Authors: Rieckermann J. , Neumann M. , Ort C. , Huisman J.L. , Gujer W.
Published: May 2018

In this paper, 60 tracer experiments in 37 different sewer reaches have been analyzed for longitudinal dispersion under dry weather flow conditions. It was found that dispersion coefficients of sewers are two to three orders of magnitude smaller than those measured in rivers and do not differ much from system to system. Suitable equations were identified to predict reasonable dispersion coefficients in sewer reaches with uniform geometry and stable flow conditions. For engineering applications that require a high degree of accuracy the performance of tracer measurements is recommended.
Monitoring of carbamazepine concentrations in wastewater and groundwater to quantify sewer leakage
Authors: Fenz R. , Blaschke A.P. , Clara M. , Kroiss H. , Mascher D. , Zessner M.
Published: May 2018

Monitoring of carbamazepine concentrations in wastewater and groundwater enables us to identify and quantify sewer exfiltration. The antiepileptic drug carbamazepine is hardly removed in wastewater treatment plants and not or just slightly attenuated during bank infiltration and subsoil flow. Concentrations in wastewater are generally 1,000 times higher than the limit of quantification. In contrast to many other wastewater tracers carbamazepine is discharged to the environment only via domestic wastewater. The results from this study carried out in Linz, Austria indicate an average exfiltration rate of 1%, expressed as percentage of the dry weather flow that is lost to the groundwater on the city-wide scale. This rate is lower than sewage losses reported in most other studies which attempted to quantify exfiltration on the basis of groundwater pollution. However, it was also possible to identify one area with significantly higher sewage losses. This method seems to be very suitable for the verification of leakage models used to assess sewer exfiltration on a regional scale.
Application of a leakage model to assess exfiltration from sewers
Authors: Karpf C. , Krebs P.
Published: May 2018

The exfiltration of wastewater from sewer systems in urban areas causes a deterioration of soil and possibly groundwater quality. Beside the simulation of transport and degradation processes in the unsaturated zone and in the aquifer the analysis of the potential impact requires the estimation of quantity and temporal variation of wastewater exfiltration. Exfiltration can be assessed by the application of a leakage model. The hydrological approach was originally developed to simulate the interactions between the groundwater and surface water, it was adapted to allow for modelling of interactions between groundwater and sewer system. In order to approximate the exfiltration specific model parameters infiltration specific parameters were used as a basis. Scenario analysis of the exfiltration in the City of Dresden from 1997 to 1999 and during the flood event in August 2002 shows the variation and the extent of exfiltration rates.
Precaution and Participatory Integrated Assessment of GM crops in Spain
Authors: David Tàbara J.
Published: May 2018

Qualitative Participatory Integrated Assessment (PIA) has been carried out to unveil the different accounts and uses of the precautionary principle and of the precautionary approach in the management of Bt commercial crops in Spain. In particular, two main interpretations have been identified: a case by case precaution (or caution) and a systemic precaution. Three scenarios on the plausible causes and consequences of commercial GM crops policy futures and the role of the precautionary principle and of precaution in them were also developed. Further research found that these scenarios could be linked to two broader worldviews about different plausible societies, models of agriculture, and of the role of ethics in the management of science and technology. It is argued that such worldviews, which go beyond the bounded rationality of scientific expertise on commercial GM crops, are used by policy makers in Spain, rather than or in conjunction with expert assessments, to make complex decisions in situations of large uncertainties and high stakes.
Integrated management of natural resources: dealing with ambiguous issues, multiple actors and diverging frames
Authors: Dewulf A. , Craps M. , Bouwen R. , Taillieu T. , Pahl-Wostl C.
Published: May 2018

Uncertainty is an increasingly important concern when trying to manage complex systems of interrelated natural resources. Scientific knowledge or necessary information may be lacking or incomplete. Additionally, the multiple and interdependent users of those resources may diverge in defining what really is at stake. When they frame issues in very different ways, ambiguity results, i.e., the existence of two or more equally plausible interpretation possibilities. Environmental management in these conditions implies a shift in attention from solving clearly delineated problems to continuous negotiating and tuning between different actors and expertise domains. This requires dealing with the frame differences in a reciprocal way by mutually acknowledging frames and connecting them. Some or all parties will have to revise, enlarge or reframe the way they relate to the issues and to each other, in order to support mutual understanding and common action. The contribution of experts does not consist then in providing total predictability nor in predefining issues and solutions, but in supporting a joint learning and negotiation process among different actors and in feeding this process with relevant information. Behavioural simulations may play an important function to stimulate multi-actor learning and negotiation processes.
Experiences with the NUSAP system for multidimensional uncertainty assessment
Authors: van der Sluijs J. , Craye M. , Funtowicz S. , Kloprogge P. , Ravetz J. , Risbey J.
Published: May 2018

This paper discusses recent experiences with the NUSAP system for multidimensional uncertainty assessment, based on case studies that vary in complexity. We show that the NUSAP method, and especially the pedigree analysis part of it, is useful to assess not only parameter uncertainty but also to systematically reflect upon (model) assumptions and problem frames. A diagnostic diagram can be used to synthesize results of quantitative and qualitative analysis. It provides an analytic tool to prioritize uncertainties according to quantitative and qualitative insights in the limitations of available knowledge. We further show that extension of the pedigree scheme to include societal dimensions of uncertainty, such as problem framing and value-laden assumptions, further promotes reflexivity and collective learning. When used in a deliberative setting, NUSAP pedigree assessment has the potential to foster a deeper social debate and a negotiated management of complex environmental problems.