bluuebunny/crossref_metadata_2025 huggingface dataset:
Rainfall data monitoring and application for urban hydrology in the Czech Republic
Authors: Krejcik J. , Krejci V. , Musilová S. , Stransky D.
Published: May 2018

With respect to increasing number of advanced technology applications for urban drainage projects in the Czech republic the requirements for relevant rain data become more important. Two research projects related to measurement, evaluation and application of rainfall data for urban hydrology purposes were launched. Suitable measuring equipment and their reliability have been studied and evaluated. The needs of high density of rain gauges for single event investigation of sewer system have been verified. The spatial distribution of rainfall doesnt influence statistical evaluation of the effects obtained by long term simulation significantly. The needs for rainfall data will be proposed for the master plan of urban drainage in Prague.
Historical rainfall for urban storm drainage design
Authors: Petrovic Jasna , Despotovic Jovan
Published: May 2018

Traditional design method for urban drainage systems is based on design storms and its major drawback is that frequencies of peak flows in the system are considered equal to frequencies of design storms. An alternative is to use historical storms with rainfall-runoff models to produce a series of possible flows in the system and their frequencies. The latter approach involves more computations and can be laborious for larger catchments. This paper considers ways to reduce the set of historical storms to be involved in design procedure and yet to lead to realistic flow frequencies. Frequencies obtained by rainfall-runoff simulation at an experimental catchment are compared with frequencies of observed peak flows in the system.
On-line monitoring of micropollutants in the river trent (UK) with respect to drinking water abstraction
Authors: Drage B. E. , Upton J. E. , Purvis M.
Published: May 2018

Severn Trent Water (STW) have been investigating the potential of using the River Trent as a drinking water supply resource. Supply and demand assessment during recent semi-drought conditions in the United Kingdom over the last few years indicates that there is a need to utilise Trent water to safeguard supplies for the East Midlands area of England when stocks derived from the River Derwent catchment are limited.

The River Trent contains the treated sewage effluent from four million people plus industry in the Midlands and along with diffuse drainage sources means that the river quality can be highly variable. In conjunction with various treatment studies on River Trent water, the pollution risks and water quality variations have been examined. The results have been used to develop an on-line monitoring station to give effective river intake protection in line with the risks found. This monitoring includes continuous low level detection (to less than 1μg/l) of multiple pesticide groups including acid herbicides, acheived by a unique development of solid phase extraction and liquid chromatography techniques.
Experimental and numerical studies of small-scale rainfall measurements and variability
Authors: Krajewski W. F. , Kruger A. , Nespor V.
Published: May 2018

A high-resolution rainfall observatory was established at the Iowa Institute of Hydraulic Research to support studies of small scale rainfall variability. It includes a vertically pointing X-band radar, a two-dimensional video disdrometer, an optical rain gauge, a standard tipping bucket raingauge, and high temporal resolution sensors for measurements of wind velocity and direction, temperature, humidity, and pressure. All the instruments are collocated. The observatory is being upgraded to include a Doppler processor for the radar, a mobile platform to enable participation in community-organized hydrometeorological experiments, and a network of about 15 high-resolution raingauges to be installed at a nearby airport. The airport network design includes innovative concepts of dual sensors constituting a single observational point, connected to the same data logger. The observational points are separated with distances ranging from 10-1000 metres. We present comparisons of data collected by the various sensors and discuss implications for radar-rainfall estimation. The capabilities of the experimental setup at IIHR will facilitate numerical studies of rainfall measurements. In particular, we present results of computational fluid dynamics calculations of the measurement error of the video disdrometer based on the high resolution observations of drop size distribution and wind velocity.
The geography and topography effects on the areal pattern of precipitation in a small prealpine basin
Authors: Sevruk B. , Nevenic M.
Published: May 2018

Analysis of altitudinal dependency of corrected summer season, June-September, precipitation data from 61 gauges shows that precipitation in the valley and on the leeward slopes of a small, rugged prealpine basin, 13 km2 in area, is greater than that on windward slopes. This indicates that (i) the redistribution of precipitation by wind can play a significant role in the spatial distribution of precipitation in mountainous areas, (ii) the use of exclusive valley positioning of gauges which is the common practice in the mountains can overestimate the precipitation on slopes and (iii) the results of studies of effects of geographic and topographic variables on the precipitation in the mountain are biased and rather network specific than physically based, and considerably depend on the general strategy of the network design including the gauge type and positioning of gauge sites. The corrections of wind-induced error were based on comparisons of precipitation from paired ground level gauges and elevated gauges. Such pairs have been situated under different exposure conditions. The corrections included also wetting and evaporation error, and amounted from 5 to 15% depending on the gauge type and site altitude, exposure and insulation.
Importance of DOC in sediments for contaminant transport modelling
Authors: Hwang Byung-Gi , Jun Kwan-Soo , Lee Young-Dae , Lung Wu-Seng
Published: May 2018

Contaminants in the interstitial waters are not only dissolved but also associated with a filterable colloidal phase such as DOC. The DOC plays an important role regulating the distribution of chemicals between particulate and dissolved phases since it binds chemicals and makes them unavailable for vertical diffusive exchange. A three-phase partitioning model that consists of free-dissolved, DOC-bound, particulate-bound components of the chemicals involved is used for the contaminant transport model in order to include the effect of DOC on the partition coefficient. The contaminant model is linked to WASP modeling framework to predict remobilization of PCBs in sediments and the fate and transport of the contaminant in overlying waters of the New Bedford Harbor where the harbor has been contaminated with PCBs and heavy metals released from electronic capacitor manufacturers. Simulation of remedial controls indicates that if no action is taken, PCB concentrations will continue to be at elevated levels. Several scenarios for the removal of contaminated sediments have been performed to reduce the elevated PCB concentrations to background levels.
Controls, computers and communications: fusion in instrumentation, control and automation of water and wastewater systems in Japan
Authors: Ohto Tohru
Published: May 2018

This article sets out the currents status of instrumentation, control and automation in Japan and the developments which are rapidly leading to a new configuration for such systems; this new configuration may best be encapsulated by the concept of ‘3C Fusion’, i.e., the fusion of controls, computing and communications.
New operational support system for high nitrogen removal in oxidation ditch process
Authors: Furukawa S. , Tokimori K. , Hirotsuji J. , Shiono S.
Published: May 2018

A new operational support system for the oxidation ditch process has been developed. It calculates the operational index from the concentration of the dissolved oxygen in the ditch and the operator decides the aeration conditions to keep the index within the target range. Simulation and experimental results have led to creation of an operational index with an optimum value for every type of aeration. For example, the ratio of aerobic to anaerobic zone length (LAER/LANA ratio) is for the 1-point continuous aeration process, the ratio of aerobic to anaerobic duration time (TAER/TANA ratio) is for the 2-point intermittent aeration process and so on. Their optimum values are all 1, suggesting that the ratio of denitrification to nitrification rates is around 1 under typical conditions of the general oxidation ditch process. These indexes are very practical because they can be obtained without complex calculation.
Rapid enzymatic detection of heterotrophic activity of environmental bacteria
Authors: Tryland I. , Fiksdal L.
Published: May 2018

Heterotrophic plate count (HPC) is considered a useful general indicator of water quality. However, the analysis time is too long (48-72h) to provide information about a decrease in water quality that may require immediate remedial measures. High numbers of heterotrophic bacteria (HB) may also interact in the analysis of coliform bacteria resulting in false low numbers. Limited information is available on the variation of cellular 4-methylumbelliferyl-heptanoate hydrolase (MUHase) activity of HB under different environmental conditions and it is not known if MUHase activity exists in all HB. In this study, MUHase activity has been evaluated for rapid (25min) detection of HPC. The MUHase activity of different bacterial isolates from environmental water samples varied by several log units. Natural water samples showed less variation in activity calculated per CFU, indicating a relatively constant ratio between numbers of bacteria with high and low enzyme levels. The MUHase activity therefore provided a rapid estimate of the HPC of the water samples. The MUHase activity was more resistant to chlorine than the HPC, and separate HPC versus MUHase activity correlation curves should be established for chlorinated and non-chlorinated water.
A titration technique for on-line nitrification monitoring in activated sludge
Authors: Gernaey Krist , Bogaert Herwig , Vanrolleghem Peter , Massone Alessandro , Rozzi Alberto , Verstraete Willy
Published: May 2018

A titrimetric method to monitor nitrification was applied on a pilot activated sludge plant for biological N removal. Mixed liquor was sampled from the aerobic compartment of the treatment plant and a titration in-sensor experiment was performed. Interpretation of the cumulative base addition curves resulting from each titration in-sensor experiment was done using both a simple slope extrapolation method and a model-based non-linear parameter estimation method. The NH4+-N concentrations obtained with both methods correlated well with the NH4+-N concentrations measured on the effluent of the pilot plant using an on-line NH4+-N analyser. Contrary to most physical/chemical NH4+-N analysers, no sample pretreatment of the mixed liquor is needed for the measurements. It is shown in detail that interpretation of the titration curves yields information about the nitrification kinetics too, which can be an important advantage for process control purposes.
Chlorination of pathogenic E coli O157
Authors: Kaneko M.
Published: May 2018

Foodborne outbreaks of infectious disease caused by enteropathogenic E coli O157 have occurred throughout Japan since 1996. This study was undertaken to check whether commonly used chlorination could effectively inactivate E coli O157 in water. Pathogenic E coli 157 could be as easily inactivated by chlorine as non-pathogenic E coli K12. Although the presence of suspended solids (<5mg/L) reduced the rate of E coli inactivation, waters obtained from properly operated treatment systems, including chlorination, would be safe against pathogenic E coli O157.
Fungi as environmental microbiological indicators
Authors: Mendes B. , Urbano P. , Alves C. , Morais J. , Lapa N. , Oliveira J. S.
Published: May 2018

An evaluation of the mycological quality of the sand beaches of the Lisboa and Vale do Tejo coastal area in Portugal was undertaken in May-October 1994. The keratinolytic fungi, yeasts, potential pathogenic and allergic and/or environmental saprophytic fungi were analysed. The results for the yeast Candida were evaluated according to the “Proposed Guidelines for the Microbiological Quality of Sand”. The data showed good/satisfactory quality of the sand beaches for the genus Candida. The results indicate that the allergic and/or environmental saprophytic fungi were the most common in sand beaches. The fungi Scopulariopsis and the yeast Candida could be used as specific indicator organisms of sand beaches quality. A new quality objective is introduced that will contribute to improve the sand beaches quality.
Service water quality monitor including hue and coloration grade
Authors: Hiraoka Mutsuhisa , Noda Naohiro , Hayakawa Chiyoji , Gotoh Keiji , Shirozu Tohru , Hosoda Saburoh , Ichinohe Masanori
Published: May 2018

The authors introduce an index of coloration grade for evaluation of service water colour. The principle of the coloration grade measurement has been derived from authors' modification of the Tristimulus Filter Method of AWWA 1992 and JWWA 1993 Standard Method, and it has the advantage of applicability to all colours in the visible range. The characteristics of the hue and coloration grade measurement has been tested in the laboratory using various coloured samples obtained from water service pipes or an aqueduct. Compared with the “colour” measured by the platinum-cobalt method, the coloration grade is more sensitive to various water coloration and close to human senses.

Applying the above stated device, a Service Water Quality Monitor was newly developed and successfully tested at several distinctive fields. It monitors three items, colour, turbidity and residual chlorine which are obligatory in Japan to be daily examined at appropriate house taps. For the field test of about six months without any manual calibration, the accuracy of the hue and the coloration grade has shown maximum deviation of only 2.5% FS compared with the measurement by means of the standard solutions once a month.
Total ammonia monitoring using an optrode and an electrochemical sample pH adjusting system
Authors: Meredith Doug , Maidment Clive , Gibbs Kim
Published: May 2018

The gas permeable ammonia probe, in everyday use, has a lower limit of detection which does not satisfy the requirements of the Environmental Regulators, for natural waters investigations. The lower limit requirement has been suggested as 25 μg/l. PTFE membranes impregnated with dyes responsive to ammonia gas concentration changes have shown that limits of detection lower than those found using gas permeable probes are possible. Research and development was instigated by M Squared Technology to produce a system using a colour measurement technique and to try and reduce the cost of ownership of on-line systems. An optrode was developed to meet the requirements of the Regulators, and the results are described in this paper. Simultaneously with this development a method was found, and patented, for changing the pH level of the sample, without the need for addition of reagents. This was developed in order to reduce maintenance and running costs on total ammonia monitors. As the system was researched and developed, the findings led to further patents being applied for, in the field of sample pH “splitting”, surface cleaning of sensors and pipe lines, and the prevention of hardness precipitation when the pH of the sample had been elevated. The paper describes the findings and results of these developments.
Development of a noncontact liquid level measuring system using image processing
Authors: Takagi Yoichi , Tsujikawa Akio , Takato Masao , Saito Takeshi , Kaida Motoko
Published: May 2018

This paper describes how the authors developed a liquid level measuring system designed to directly analyze images of liquid surfaces. This measuring system is based on the principle that the contour of the image of a slanted metal strip placed in a liquid shows an inflection point on the liquid interface. This liquid level measuring system using image processing is useful in automatically measuring the levels of water, oil, liquefied gases, and alcoholic beverages. Among the features of this measuring system are: (1) it is of the noncontact type, so that there is no need to install a sensor or other high-precision devices close to the liquid to be measured; (2) it can be installed in a way not affected by the liquid; (3) the scale and the liquid surface can be analyzed on an image basis directly, so that periodic recalibration is unnecessary; (4) deviations in measurements can be easily detected by visually checking the monitor screen; (5) images from more than one camera can be processed with a single image processor to reduce total costs.
Biological pretreatment of poultry processing wastewater
Authors: Rusten Bjørn , Siljudalen Jon G. , Wien Asgeir , Eidem Dagfinn
Published: May 2018

A biological pretreatment plant for poultry processing wastewater was designed, using an aerated equalization tank followed by two high-rate moving bed biofilm reactors (MBBRs) in series. No solids separation and sludge handling was installed. The solids from the pretreatment plant were discharged to the municipal sewer together with the pretreated wastewater. The pretreatment plant performed well, even at organic loads significantly higher than the design values. With a specific biofilm surface area of 250 m2/m3 and a total volumetric organic load of 30–45 kg COD/m3 × d on MBBR1, the removal of filtered COD was as high as 80% over MBBR1 and 90–95% over MBBR1 plus MBBR2.
Sludge retention time in the secondary clarifier effects on the growth of Microthrix parvicella
Authors: Hagland Eva , Westlund Åsa Dillner , Rothman Maria
Published: May 2018

Microbiological examinations have been performed over the last 3 years at 3 large sewage treatment plants in the greater Stockholm area. All 3 plants have periodically suffered from excessive growth of the filamentous bacterium Microthrix parvicella. The growth of Microthrix parvicella was favored by low sludge loading. Results from various plants and from the various parallel systems within the individual plants were compared. The bacterial composition of the activated sludges differed in ways that could not be explained by the sludge loading or the sewage composition. Biological processes in the secondary clarifiers seem to influence the competition between the different organisms in the activated sludge. A clear relationship was shown between high sludge retention time in the secondary clarifiers, VFA production in the return activated sludge (RAS) and a high abundance of Microthrix parvicella.
Enrichment and characterization of an anaerobic methyl ethyl ketoxime degrading culture from an anoxic/anaerobic/aerobic activated sludge sequencing batch reactor
Authors: Love Nancy G. , Rust Mary E. , Terlesky Kathy C.
Published: May 2018

An anaerobic enrichment culture was developed from an anoxic/anaerobic/aerobic activated sludge sequencing batch reactor using methyl ethyl ketoxime (MEKO), a potent nitrification inhibitor, as the sole carbon and energy source in the absence of molecular oxygen and nitrate. The enrichment culture was gradually fed decreasing amounts of biogenic organic compounds and increasing concentrations of MEKO over 23 days until the cultures metabolized the oxime as the sole carbon source; the cultures were maintained for an additional 41 days on MEKO alone. Turbidity stabilized at approximately 100 mg/l total suspended solids. Growth on selective media plates confirmed that the microorganisms were utilizing the MEKO as the sole carbon and energy source. The time frame required for growth indicated that the kinetics for MEKO degradation are slow. A batch test indicated that dissolved organic carbon decreased at a rate comparable to MEKO consumption, while sulfate was not consumed. The nature of the electron acceptor in anaerobic MEKO metabolism is unclear, but it is hypothesized that the MEKO is hydrolyzed intracellularly to form methyl ethyl ketone and hydroxylamine which serve as electron donor and electron acceptor, respectively.
Sulfate reduction and sulfide oxidation in aerobic mixed population biofilms
Authors: Okabe Satoshi , Matsuda Takayuki , Satoh Hisashi , Itoh Tsukasa , Watanabe Yoshimasa
Published: May 2018

The microzonation of O2 respiration, H2S oxidation and SO42− reduction in aerobic biofilms grown on rotating disk reactors of a sewage treatment plant was studied by measuring concentration profiles with microelectrodes for O2, S2− and pH. The vertical distribution of sulfate-reducing bacteria (SRB) in the biofilms was also determined by the conventional culture-dependent MPN method and fluorescently labeled 16S rRNA-targeted oligonucleotide probes for SRB. The SRB probe stained cells were distributed throughout the biofilm with a distinct higher fluorescence intensity in the middle part of the biofilm. This result corresponded well with O2 and S2− concentration gradients measured by microelectrodes, showing sulfate reducing activity was largely restricted to a narrow anaerobic zone located in the middle of the biofilm. Measurements of accumulation of reduced sulfur compounds (FeS, FeS2 and SO) in the biofilm indicated that the H2S produced by SRB became oxidized by O2 and other oxidants, probably ferric/ferrous hydrates, and precipitated as FeS and SO just above the sulfate reduction zone.
Population dynamics and biofilm composition in a new three-phase circulating bed reactor
Authors: Lazarova Valentina , Bellahcen Danièle , Rybacki Danièle , Rittmann Bruce , Manem Jacques
Published: May 2018

The biofilm characteristics of a novel three-phase reactor, the circulating bed reactor (CBR), were studied using industrial prototype fed with primary and secondary settled effluent in conditions of tertiary N and secondary C+N nitrification. The results showed a high nitrification rate close to the intrinsic values for N and C+N conditions: up to 2 and 0.6 kgN-NH4 m−3 d−1, or 1.88±0.26 and 0.22±0.07 gN g−1 PR d−1, respectively. The application of an integrated approach for biofilm analysis enabled the better understanding of biofilm dynamics. The biofilm remained relatively thin, below 100 μm, indicating an effective control of the biofilm development. Protein, measured by the conventional colometric method and pyrolysis-GC-MS, was the major fraction accounting for up to 35% of the biomass dry weight and 58% of the biopolymer content. The polysaccharide's fraction remained very low (<3%). The ribosomal RNA probes analysis confirmed the predominance of bacterial cells in the CBR biofilm (80-86% of bacteria versus the universal probe) showing a high proportion of nitrifying bacteria accounting for up to 50% and 27% in the N and C+N removal respectively. Nitrosomonas predominated in tertiary nitrification whereas carbon input led to the appearance of other ammonia oxidizers. This particular composition was characterized by a high state of oxidation of the biomass, expressed by the low COD/DW ratio of about 0.85. In conclusion, it can be stated that this new three-phase bioreactor ensures a high nitrification rate through an effective biofilm control promoting the development of bacterial cells, especially nitrifying bacteria, and minimizing exopolysaccharides production.
Biofilm population dynamics in a trickle-bed bioreactor
Authors: Hekmat D. , Amann R. , Linn A. , Stephan M. , Stoffels M. , Vortmeyer D.
Published: May 2018

The biodegradation of polyalkylated benzenes (Solvesso 100®) from waste air in a trickle-bed bioreactor was studied. The immobilized mixed population was analyzed by in-situ hybridization using group-specific fluorescence labeled rRNA-target oligonucleotides. It was shown that the growth conditions of an immobilized system are not comparable to those of a submerged culture. Variations of the concentrations of the α-, β-, and γ-subclasses of the proteobacteria of the biofilm population were measured. A significant increase of the biodegradation rate and, thus, of the activity of the microbial mixed population present in the biofilm was observed by applying a forced cyclical substrate time function.
Stratification of microbial metabolic processes and redox potential change in an aerobic biofilm studied using microelectrodes
Authors: Yu Tong , Bishop Paul L.
Published: May 2018

In this study we used oxygen, sulfide, redox potential and pH microelectrodes to examine the stratification of microbial metabolic processes and the change of redox potential within an aerobic biofilm used to treat azo dye containing wastewater. These microelectrodes have tip diameters of 3 to 20 μm and a high spatial resolution. They were used to measure the profiles of oxygen, total dissolved sulfide, redox potential and pH as a function of depth in the biofilm. These profiles demonstrated that oxygen was depleted at 550 μm from the surface and the deeper section of the biofilm was actually anaerobic. While aerobic oxidation took place only in a shallow layer near the surface, sulfate reduction occurred in the deeper anaerobic zone, even with a low concentration of sulfate (6.75 mg/l as SO2−) in the bulk solution. We discovered a sharp decrease of redox potential (271 mV) from a positive potential to a negative potential within a very narrow band of 50 μm near the interface between the aerobic zone and the sulfate reduction zone. The new experimental findings support the concept of stratification of the microbial metabolic processes in biofilms.
Influence of operational variables on enzymatic tests applied to monitor the microbial biomass activity of a biofilter
Authors: Le Bihan Y. , Lessard P.
Published: May 2018

Enzymatic assays were used to monitor the biomass of a biofilter working under different operational conditions. In backwash waters used as biomass source, many hydrolytic enzymes as well as dehydrogenase expressed in volumetric units seem to correlate with volatile suspended solids (VSS) and with the volumetric feeding mass. However, only the specific concentration of β-Glucuronidase correlates negatively with this volumetric feeding mass. The influent temperature affects simultaneously the specific concentration of β-Glucosidase, the headloss behaviour and the total sugars/VSS ratio. For the properties of the biomass, the sludge volume index (SVI) of the backwash waters correlates with Leu-aminopeptidase, suggesting that this enzyme could have been produced by filamentous organisms.
Encapsulation of heavy metals on spent fluid catalytic cracking catalyst
Authors: Sun D. , Li X. Z. , Brungs M. , Trimm D.
Published: May 2018

Vanadium and nickel were found as major contaminants on spent FCC catalyst at levels of 3518 ppm and 3225 ppm, respectively. XPS results indicated that vanadium and nickel were in oxide form on spent FCC catalysts. Leaching tests (TCLP) showed that vanadium from spent FCC catalysts poses an environmental problem if disposed by landfill. It was found that encapsulation treatment with up to 60 wt % spent FCC catalyst in Portland cement, is an effective means of stabilization. The strength of standard specimens containing catalyst was much lower than that of standard specimens made with same weight percentage of sand.
A model of two-dimensional biofilm morphology
Authors: Hermanowicz Slawomir W.
Published: May 2018

A mathematical model of biofilm development was proposed. The model, which can be classified as a cellular automaton, is based on simple local rules for growth and detachment of individual cells. Results of several numerical simulations suggest that the thickness of concentration and hydrodynamic boundary layers may have an important effect on the developing biofilm structure. When external mass transfer limitations are significant, model biofilms develop an open structure. When the concentration boundary layer is reduced and external mass transfer is enhanced, a dense layer of a biofilm develops. Biofilm strength to withstand erosion has a smaller but also significant effect on its structure.
Single-stage anaerobic/aerobic biotreatment of resin acid-containing wastewater
Authors: Guiot S. R. , Stephenson R. J. , Frigon J.-C. , Hawari J. A.
Published: May 2018

The present study compares the coupled anaerobic/aerobic integrated system (CANOXIS) operated at different aeration and liquid recycle rates to the conventional upflow anaerobic sludge bed (UASB) system for the laboratory scale treatment of a resin acid-containing effluent. Dehydroabietic and abietic acids were added in equal proportions to a sucrose-based feed stock. Even under oxygenation conditions, methane was formed, indicating that the aerobic and facultative microorganisms consumed oxygen fast enough to maintain a reduced microenvironment essential to the methanogens. Eight weeks of resin acid loading at 100 mg/L exerted no significant effects on the high efficiency and stable performance of UASB reactors. The CANOXIS systems showed with time a reduced discharge of residual resin acids in the effluent and a decrease of the amount of resin acids adsorbed onto the biomass when compared to the UASB reactor.
Adaptation of the microbial adhesion to hydrocarbon test (MATH) for measuring activated sludge hydrophobicity
Authors: Guellil A. , Block J.-C. , Urbain V.
Published: May 2018

The “microbial adhesion test to hydrocarbon” (MATH) developed by Rosenberg et al. gives a cell hydrophobicity index (A% = percentage of adhesion) and is easy to perform. However it is not applicable with any degree of accuracy to activated sludge even when dispersed by sonication, because of the presence of aggregated and free cells and of amphiphilic organic polymers from sludge which lead to the formation of a stable emulsion. The effect of emulsion formation is a decrease in bacterial number from the aqueous phase by adhesion on to, and trapping between, the droplets of octane. This induces an overestimation of the hydrophobicity of the bacterial suspension.

To solve this problem, we propose modifications of the MATH which may be used for any bacterial suspension and which expresses the bacterial adsorption equilibrium between the surface of the octane droplets and the water phase. The test starts just as for the regular MATH by mixing the bacterial suspension and octane. The resulting emulsion is sampled, and then serially washed 10 times with 5 ml of MilliQ water. By plotting the decreasing numbers of bacteria recovered in the washing solutions against the number of bacteria adhering to octane droplets, a linear relationship is obtained the slope of which equals an equilibrium constant Ke. For the 5 samples of sludge tested, Ke (values from 1.3 to 3.2) appears to be a more accurate and sensitive parameter than A% (values from 62 to 86%).
Mechanism of bacterial and viral transport through microfiltration membranes
Authors: Herath Gemunu , Yamamoto Kazuo , Urase Taro
Published: May 2018

Microorganisms such as Qβ, MS2, T4 virus and several bacteria strains in Pseudomonas, Alcaligenes and E-coli groups were filtered with different pore size nuclepore and anopore flat sheet membranes in dead end mode. The obtained rejection results were analyzed with existing pore models in which the rejection is related to the ratio of solute size to pore size. The existing pore models (transport equations) were adjusted to accommodate the microfiltration range particles. The adjusted pore models showed good agreement with the obtained experimental rejection results for virus while the bacteria rejection results showed a deviation. This deviation is partially explained with the wide size distribution of bacteria. The equivalent spherical diameter can be used to represent the virus size while the oval diameter of the cells may be the best possible dimension for bacteria size in membrane filtration. This determination showed the possibility of bacteria cells approaching the membrane pores in their longitudinal direction.
Activated sludge foaming: what causes hydrophobicity and can it be manipulated to control foaming?
Authors: Stratton Helen , Seviour Bob , Brooks Peter
Published: May 2018

Activated sludge aeration tanks frequently suffer from the formation of a stable foam on their surfaces, a problem which results in increased operating costs and reduces performance. Current control strategies are often unsuccessful, mainly because of a lack of understanding of the microbes involved, and often employ expensive and environmentally undesirable procedures, such as the addition of chemicals. Here we have attempted to better understand the mechanism(s) involved in foam formation. We have investigated the possible relationship between the mycolic acid content in a Rhodococcus rhodochrous strain isolated from foam, its cell surface hydrophobicity (CSH) and ability to form stable foam. Results show that mycolic acid composition is not the only contributor to CSH, nor is the CSH the only factor responsible for foam formation and stabilisation. Other possible explanations for mechanisms of foaming and ways to control it are addressed.
Behaviour of activated sludge from a system with anoxic phosphate uptake
Authors: Šorm R. , Bortone G. , Wanner J. , Tilche A.
Published: May 2018

Activated sludge from a new activated sludge modification for biological phosphorus and nitrogen removal was studied. Population dynamics and the phenomenon of anoxic phosphate uptake with simultaneous denitrification were investigated.

The ability of the process to remove nutrients and to suppress filamentous bulking was studied. The course of phosphate concentrations along the tested system showed an anoxic phosphate uptake with simultaneous denitrification. The mechanism of anoxic phosphate uptake was confirmed using kinetic batch tests.
Nitrogen loss in a nitrifying rotating contactor treating ammonium rich leachate without organic carbon
Authors: Siegrist H. , Reithaar S. , Lais P.
Published: May 2018

Extended loss (up to 70%) of nitrogen is observed in a nitrifying rotating biological contactor (RBC) treating ammonium - rich leachate of a hazardous waste landfill. Due to pretreatment (flocculation, BOD-removal, activated carbon) DOC was less than 20 mg/l so heterotrophic denitrification can be excluded. The nitrification rate reaches 3-4 g NH4-N m−2 d−1 at a pH of 7-7.3 in the first two of three RBC compartments. An increasing partial pressure of oxygen and ammonium concentration favor nitrogen removal over ammonium oxidation. The reduction of nitrite produced in the aerobic biofilm layer close to the surface might therefore be coupled with ammonium oxidation and takes place in the deeper or temporarily anoxic layer of the biofilm.
Anaerobic processes in activated sludge
Authors: de Beer Dirk , Schramm Andreas , Santegoeds Cecilia M. , Nielsen Helle K.
Published: May 2018

We found anoxic zones in aerated activated sludge flocs, and demonstrated denitrification under normal operating conditions. Sulfate reduction was not found. Micro-environments and microbial conversions in flocs from bulking and non-bulking activated sludge were determined with microsensors for H2S, O2, NO2− and NO3−. Denitrification and sulfate reduction rates were mmeasured with 15N- and 35S-tracer techniques. We showed that under normal reactor conditions (ca. 20% air saturation) anoxic zones develop within flocs allowing denitrification. The denitrification rates amounted to 40% of the rates under anoxic conditions. At 100% air saturation no anoxic zones were found and no denitrification occurred. However, in flocs from bulking sludge (at 20% air saturation) anoxic zones were absent and denitrification did not occur. In bulking sludge only at total anoxia was denitrification found. Confocal microscopy showed that flocs from bulking sludge were much looser than those from non-bulking sludge. The absence of anoxic zones and of denitrification was attributed to the open floc structure, allowing advective oxygen transport.

Sulfate reduction was not detected in any of the sludges tested by microsensors or by tracer techniques even under anoxic conditions. this indicates that the sulfur cycle (sulfate reduction and sulfide oxidation) does not play a role in mineralization processes and bulking in activated sludge. Preliminary molecular work (in situ hybridization with the 16S-rRNA probe SRB385) indicated the presence of small amounts of sulfate reducing bacteria in all sludges. Either the probe is not specific or the sulfate reducers present are not active under reactor conditions.
Emissions of porewater compounds and gases from the subaquatic sediment disposal site “rodewischhafen”, hamburg harbour
Authors: Kussmaul M. , Groengroeft A. , Koethe H.
Published: May 2018

In the year 1993 a confined and unused harbour basin was used to store 290,000 m3 of fine-grained dredged material from Hamburg harbour. About 70% of the deposit surface was water covered. The edge areas were above the water table and covered with reed. Emissions of dissolved compounds into the groundwater, as well as surface gas emissions were measured from 1994 to 1996. As indicators for water fluxes from the deposit we used NH4+ and HCO3− because of their high concentrations in mud porewater in comparison to groundwater. The average concentrations of NH4+ and HCO3− in the porewater increased during 2 years from 85 to 250 mg NH4+ 1−1 and from 2.0 to 3.1 g HCO3− 1−1, while the groundwater samples showed constant values of 8 mg NH4+ 1−1 and 0.7 g HCO3− 1−1. Furthermore, the average gas emissions over the water surface were 3.2 g CH4 m−2 d−1 and 0.8 g CO2 m−2 d−1. In contrast, no methane and 3.0 g CO2 m−2 d−1 were emitted from land areas. The results indicated, that there were no significant emissions of mud porewater compounds into the groundwater but high CH4-emissions over the water covered surface of the mud deposit.
Relocation of dredged material from Hamburg harbour in the River Elbe
Authors: Netzband A. , Christiansen H. , Maaß B. , Werner G.
Published: May 2018

Besides the beneficial use of dredged material, sustainable relocation, which means keeping the sediments in the natural aquatic material circulation, is one goal for handling dredged material in the port of Hamburg. Decreasing contamination the River Elbe and new dredged material guidelines provide a basis for this. With comprehensive investigations, near- and far-field transport and the effects of relocation regarding the water quality and the benthic community were determined thus deveoloping conditions for future operating strategies.
Environmental risk assessment of surface water and sediments in Copenhagen harbour
Authors: Andersen Helle Vang , Kjølholt Jesper , Poll Christian , Dahl Steen Øgaard , Stuer-Lauridsen Frank , Pedersen Finn , Bjørnestad Estelle
Published: May 2018

The environmental risk assessment of Holmen, a former naval base, included characterisation of the sediments with regard to pollution with xenobiotics, heavy metals, nutrients and bacteria, and ecotoxicity. A simple hydraulic model was established, and the release of substances from the sediment to the water was assessed. Sediment biotests with Corophium volutator and porewater biotests with Skeletonema costatum and Acartia tonsa were conducted. The sediment was characterised as strongly contaminated in the major parts of the investigated area. Based on the application of the acid volatile sulfide method it was concluded that practically none of the heavy metals were bioavailable. Both the sediment and the porewater from a number of stations were toxic. The toxicity did not appear to be attributable to the content of heavy metals, more likely to other contaminants. Furthermore, the sediment, which has served as a sink for accumulation of contaminants over a period of many years, also may constitute a source of contamination due to potential release of heavy metals and xenobiotics from the sediment to the water in some areas. The release appears to give rise to concentrations above the EU Water Quality Objectives at some stations.
Monitoring of environmental effects and process performance during biological treatment of sediment from the petroleum Harbour in Amsterdam
Authors: Stefess Guus C.
Published: May 2018

A full-scale (470 m3) process for biological treatment of dredging spoil from the Petroleum Harbour in Amsterdam has been monitored during a pilot project. The dredging spoil was heavily polluted with polycyclic aromatic hydrocarbons (PAH) and mineral oil. The remediation chain involved dredging, transport of dredged spoil, hydrocyclone separation, froth flotation of the coarse particles, and biological treatment of the silt fraction (<20 μm) in stirred bioractors. The independent monitoring was aimed at recording the environmental effects, product quality and performance of the biological process.

Hydrocyclone separation (cut point 20 m) resulted in two bulk streams: 65% sand and 30% silt (based on total dry weight of the input). The sand was cleaned and could be reused as building material. PAH and mineral oil were successfully concentrated in the silt fraction (<20 μm), which was treated biologically. Biological treatment during continuous feeding of fine fraction, at a residence time of 8-10 days for the entire bioreactor system, resulted in considerably reduced mineral oil and PAH contents. Furthermore, the leaching of organic contaminants was reduced, as well as the ecotoxicity. The obtained silt product however did not meet the demands, and had to be landfilled. Minor emissions of contaminants were measured in wastewater and offgas. The energy and chemicals consumption were acceptable.

The biological process appears to be promising for the treatment of less-severely contaminated dredged material.
Simultaneous removal of Cr(VI) and phenol in chemostat culture of E. coli ATCC 33456 and P. putida DMP-1
Authors: Wang Y. T. , Chirwa E. M.
Published: May 2018

A chemostat coculture consisting of a phenol-degrading organism, P. putida, and a Cr(VI)-reducing strain, E. coli ATCC 33456, was evaluated for its potential to simultaneously remove phenol and Cr(VI). Steady-state operating conditions were obtained with near complete removal of phenol and Cr(VI) under a range of influent concentration of phenol (233–2541 mg/l), influent Cr(VI) (1–10.3 mg/l), and liquid detention time (2–6.7 days).
Hydrolysis of organic wastewater particles in laboratory scale and pilot scale biofilm reactors under anoxic and aerobic conditions
Authors: Janning K. F. , Le Tallec X. , Harremoës P.
Published: May 2018

Hydrolysis and degradation of particulate organic matter has been isolated and investigated in laboratory scale and pilot scale biofilters. Wastewater was supplied to biofilm reactors in order to accumulate particulates from wastewater in the filter. When synthetic wastewater with no organic matter was supplied to the reactors, hydrolysis of the particulates was the only process occurring. Results from the laboratory scale experiments under aerobic conditions with pre-settled wastewater show that the initial removal rate is high: rV, O2 = 2.1 kg O2/(m3 d) though fast declining towards a much slower rate. A mass balance of carbon (TOC/TIC) shows that only 10% of the accumulated TOC was transformed to TIC during the 12 hour long experiment. The pilot scale hydrolysis experiment was performed in a new type of biofilm reactor - the B2A® biofilter that is characterised by a series of decreasing sized granular media (80-2.5 mm). When hydrolysis experiments were performed on the anoxic pilot biofilter with pre-screened wastewater particulates as carbon source, a rapid (rV, NO3=0.7 kg NO3-N/(m3 d)) and a slowler (rV, NO3 = 0.3 kg NO3-N/(m3 d)) removal rate were observed at an oxygen concentration of 3.5 mg O2/l. It was found that the pilot biofilter could retain significant amounts of particulate organic matter, reducing the porosity of the filter media of an average from 0.35 to 0.11. A mass balance of carbon shows that up to 40% of the total incoming TOC accumulates in the filter at high flow rates. Only up to 15% of the accumulated TOC was transformed to TIC during the 24 hour long experiment.
An investigation of the biological fouling in the filtration of seawater
Authors: Williams C. J. , Edyvean R. G. J.
Published: May 2018

This paper investigates the nature of the biological fouling of cartridge filters during the filtration of North sea water. Biological fouling is manifested through reduced filtration performance and short filter element life. The fouling of two different types of cartridge filter (coarse, 80 μm and fine, 5 μm) operated on an offshore oil production system was investigated over a two year period. The effect of seasonality on the accumulation of both organic and inorganic particulate material on both filter types was assessed. The results were correlated with the life of the elements in service. Filter life was found to be predominantly affected by the particle size distribution of the material within the seawater. Consequently, filter life was shortest during the spring and autumn, coinciding with the occurrence of the plankton blooms, and longest during the winter when the average particle size was larger. The presence of protein and lipid was found to contribute to filter fouling.
Competition between methanogenesis and sulfidogenesis in anaerobic wastewater treatment
Authors: Zhou Gong-Ming , Fang Herbert H. P.
Published: May 2018

This study was conducted to investigate the methanogenic and sulfidogenic activities of biomass in a UASB reactor treating wastewater containing benzoate (680 mg l−1) and sulfate (increased from 1080 to 2680 mg l−1) at 37°C and 12 hours of hydraulic retention. Results showed that after 120 days of acclimation, sludge consistently removed 99.5% of benzoate regardless of increased sulfate concentrations. Sulfidogenesis gradually out-competed methanogenesis during the acclimation phase, as indicated by the increase of sulfate-reducing efficiency (up to 99%) accompanied by the decrease of methane production. Overall sulfate removal efficiency was limited after the reactor had reached its maximum sulfate reduction rate of 2.1 g S (l d−1). Further increasing sulfate concentration from 1080 mg l−1 to 2680 mg l−1 lowered the sulfate-reducing efficiency from 85% to 39%. Flow of available electrons toward sulfidogenesis increased with the decrease of benzoate concentration, and was only slightly affected by the sulfate concentration or the benzoate/SO42−-S ratio.
Treatment characteristics of high strength fermentation wastewater consisting of high sulfate and ammonia by UAHB process
Authors: Imai Tsuyoshi , Ukita Masao , Sekine Masahiko , Nakanishi Hiroshi , Fukagawa Masayuki
Published: May 2018

In this study, the formation process of granules and treatment characteristics were discussed for an Upflow Anaerobic Hybrid Blanket (UAHB) reactor, adding water absorbing polymer particles (WAP) for treating a fermentation process wastewater consisting of high sulfate and ammonia. Sulfide toxicity to methanogenic bacteria and the TOC/SO42− ratio that was usually used as an index of inhibition to methanogenesis were also examined. The results indicated that the granules could be developed in an UAHB process, in which a filter was installed in the upper part of reactor and WAP were also added into inoculum, for treating sulfide- and ammonia-rich wastewater, and inhibition caused by sulfide did not occurred when free hydrogen sulfide concentration was less than 200 mgl−1. Therefore, the UAHB process in the presence of adding WAP was shown to have a better stability for treating the refractory wastewater. The results also showed that total dissolved sulfide concentration had to be considered for inhibition assessment as well as the TOC/SO42− ratio.