bluuebunny/crossref_metadata_2025 huggingface dataset:
Pseudomonas aeruginosa as an indicator of health risk in water for human consumption
Authors: de Victorica J. , Galván M.
Published: May 2018

During an outbreak of gastroenteritis in 28 children living in a small neighbourhood of Cuernavaca city (Mexico), a survey was performed to evaluate the confidence in coliform bacteria as sole indicators of potability of drinking waters. A primary infection by E. coli and a secondary by Pseudomonas aeruginosa was diagnosed in five of the children and the drinking water provided by a well was suspected as a transmission source. General and household distribution systems, household filters and bottled waters were evaluated for total and faecal coliforms, family Enterobacteriaceae, Paeruginosa and residual chlorine. In every sample, pathogenic/opportunistic bacteria were isolated even in the absence of coliforms and in the presence of residual chlorine. Arbitrarily assigned “pollution/risk levels” indicated that the most elevated risk was most frequently associated with storage in tanks and with bacterial colonisation in the pipeline system and commercial household filters where high levels of Paeruginosa were determined. A probability of correspondence between the presence of this bacterium and the secondary gastrointestinal infection diagnosed was found pointing towards a need for the inclusion of other microorganisms, one of which may be Paeruginosa, as indicators of health risk associated with drinking waters in Mexico.
Waterborne epidemics in Finland in 1998-1999
Authors: Miettinen I. T. , Zacheus O. , von Bonsdorff C-H. , Vartiainen T.
Published: May 2018

Fourteen waterborne epidemics occurred in Finland during 1998-1999. About 7,300 illness cases were registered in these outbreaks. All except one of the waterborne epidemics were associated with undisinfected groundwaters. An equal number of waterborne epidemics occurred in public and private water systems, but most cases of illness occurred in public water systems. The three largest epidemics comprised 6,700 illness cases. Insufficient purification treatment unable to remove Norwalk-like viruses caused the only waterborne epidemic in a surface water plant. The main reasons for groundwater outbreaks were floods and surface runoffs which contaminated water. Norwalk-like viruses caused eight and Campylobacter three of the outbreaks. In two cases the epidemic ceased by the exhaustion of susceptible persons in the exposed community but in most cases it was terminated by changing the water source, boiling the drinking water, and starting chlorination.
Use of rapid enzymatic assays to study the distribution of faecal coliforms in the Seine river (France)
Authors: George I. , Petit M. , Theate C. , Servais P.
Published: May 2018

In 1997 and 1998 faecal contamination of the Seine river and its estuary was studied for the first time by rapid enzymatic methods, based on the presence of the β-D-glucuronidase enzyme in E. coli, in parallel with traditional plate counts of faecal coliforms on specific culture medium. Our study focused on a 450 km stretch of the river, including the Parisian area, and presenting highly variable levels of faecal pollution. Both methods showed that wastewater outfalls of the Parisian area and the presence of a maximum turbidity zone (at the mouth of the estuary) had a strong impact on the abundance of faecal coliforms in the river. Downstream from the Parisian outfalls, β-D-glucuronidase activity measurements decreased 5-6× less rapidly than plate counts suggesting that rapid enzymatic assays could detect enzymatically-active but non-culturable bacteria.
Helicobacter pylori in water systems for human use in Mexico City
Authors: Mazari-Hiriart M. , López-Vidal Y. , Calva J. J.
Published: May 2018

Helicobacter pylori infection is associated with peptic ulcers and gastric cancer in humans. Transmission of H. pylori is still not certain with some epidemiological data suggesting water as a possible transmission route. The objective of this study was to detect H. pylori 16S rRNA gene in five water systems in the Mexico City area. Samples were taken between 1997 and 2000 from extraction wells (system 1), from dams used as water sources, both pre- and post-treatment (systems 2 and 3), treated wastewater (system 4) and non-treated wastewater (system 5). Detection of the H. pylori 16S rRNA gene in water samples was carried out using nested PCR in 139 water samples and confirmed by using cagA gene detection by PCR-hybridisation. The results showed the presence of H. pylori in 58 (42%) of the water samples in total with a prevalence of 68% in system 1, 100% in system 2, 0% in system 3, 17% in system 4 and 20% in system 5. This first stage showed the presence of H. pylori in the tested water systems; nevertheless, viability of the microorganism in water and vegetables needs to be confirmed as well as demonstration of a relationship between human and environmental strains.
Inactivation of Cryptosporidium parvum oocysts with sequential application of ozone and combined chlorine
Authors: Rennecker J. L. , Corona-Vasquez B. , Driedger A. M. , Rubin S. A. , Mariñas B. J.
Published: May 2018

Single-step inactivation experiments with ozone and monochloramine revealed the presence of a CT lag followed by pseudo-first order inactivation kinetics. Sequential disinfection experiments with ozone followed by monochloramine revealed that ozone pretreatment resulted in the removal of a more prominent CT lag observed for monochloramine. In addition, the rate of inactivation for ozone-pretreated oocysts was approximately 2.5× greater than that observed for the post-lag phase portion of the monochloramine primary inactivation curve.
Occurrence of Cryptosporidium in Japan and counter-measures in wastewater treatment plants
Authors: Suwa M. , Suzuki Y.
Published: May 2018

The outbreak of cryptosporidiosis in Ogose in 1996 forced the wastewater treatment authorities to rethink the level of contamination by Cryptosporidium of wastewater and waters in the watersheds and counter-measures in wastewater treatment plants. A survey of Cryptosporidium concentrations in wastewater and treated wastewater conducted nationwide showed relatively low levels. Also, evaluation of wastewater treatment showed a 2 log oocyst removal with an activated sludge process and an additional 1 log removal with coagulant dosing.
Behaviour of pathogenic E. coli and Salmonella enteritidis in small domestic sewage treatment apparatus (“Johkasou”)
Authors: Kaneko M. , Nambu T. , Tokoro M.
Published: May 2018

“Johkasou” is a small sewage treatment apparatus commonly used in Japan which can effectively treat domestic wastewater in places where a public sewage system is difficult to supply. The behaviour of enterohaemorrhagic E. coli 0157 and Salmonella enteritidis in a “Johkasou” was studied. Their reduction rates depended significantly on the water temperature in the “Johkasou” with minimal decrease in numbers at 10°C within 48 h. The reduction rates increased at 20°C and 30°C where 4 log reduction could be expected. The reduction rates were influenced by the BOD of the solutions that contained the pathogens with the lower the BOD the higher the reduction rate. The reduction rates were about the same between both pathogens. The result showed that it was necessary to disinfect the effluent as some pathogens can pass through the apparatus when some users of the apparatus excrete pathogens.
Detection and rapid differentiation of human enteroviruses in water sources by restriction enzyme analysis
Authors: Vivier J.C. , Clay C.G. , Grabow W.O.K.
Published: May 2018

The objective of this study was to assess the application and efficiency of molecular techniques for the detection and serotyping of enteroviruses from environmental water samples. Samples of water were collected at regular intervals upstream and downstream of an informal settlement. Techniques for the detection of enteroviruses included a reverse transcription polymerase chain reaction (RT-PCR), nested PCR (n-PCR) and Sabin-specific triplex PCR. A specific 297 bp fragment was amplified by the n-PCR and subjected to restriction enzyme (RE) analysis to differentiate between various serotypes of prototypical enteroviruses. Enteroviruses that gave inconclusive restriction patterns were typed by partial sequencing of the VP1 region. Results indicated a high incidence of enteroviruses, predominantly coxsackie B viruses. The results on polioviruses, as well as other enteroviruses, contributed valuable information on enteroviruses circulating in the community. The molecular approach described here proved suitable for the rapid, sensitive, specific and cost effective, simultaneous detection and typing of enteroviruses in water.
Benchmarking initiatives in the water industry
Authors: Parena R. , Smeets E.
Published: May 2018

Customer satisfaction and service care are every day pushing professionals in the water industry to seek to improve their performance, lowering costs and increasing the provided service level. Process Benchmarking is generally recognised as a systematic mechanism of comparing one's own utility with other utilities or businesses with the intent of self-improvement by adopting structures or methods used elsewhere. The IWA Task Force on Benchmarking, operating inside the Statistics and Economics Committee, has been committed to developing a general accepted concept of Process Benchmarking to support water decision-makers in addressing issues of efficiency.

In a first step the Task Force disseminated among the Committee members a questionnaire focused on providing suggestions about the kind, the evolution degree and the main concepts of Benchmarking adopted in the represented Countries. A comparison among the guidelines adopted in The Netherlands and Scandinavia has recently challenged the Task Force in drafting a methodology for a worldwide process benchmarking in water industry.

The paper provides a framework of the most interesting benchmarking experiences in the water sector and describes in detail both the final results of the survey and the methodology focused on identification of possible improvement areas.
Odour removal with a trickling filter at a small WWTP strongly influenced by the tourism season
Authors: Patria L. , Cathelain M. , Laurens P. , Barbere J. P.
Published: May 2018

Etaples-Le Touquet's wastewater treatment plant (WWTP) is based on a coastal area of the Artois-Picardie region. The pollution load can vary from 20,000 p.e. to 60,000 p.e. over a weekend or in summer. The Collectivity and the Water Agency decided to cover and ventilate the main odour source points of the plant. The foul air was directed to a 2,500 m3/h inorganic bed biofilter (Alizair(r)) for odour control. An odour monitoring took place during the first year of operation taking into account cold and warm seasons, high and low tourism seasons.

The Alizair biofilter appeared an appropriate odour control process for small sized wastewater treatment plants, easy to operate and efficient even in areas where tourism seasons have a great impact on the pollution load arriving at the plant. The neighbourhood did not complain about odours any more and the operator was very confident with such a simple and effective system.

The local Authorities and the Water Agency agreed to recommend Alizair biofilters with an autotrophic biomass adapted in the case of an old WWTP that cannot be up graded any more or for large pumping stations and wastewater storage prior treatment.
Excess sludge reduction in activated sludge processes by integrating biomass alkaline heat treatment
Authors: Rocher M. , Roux G. , Goma G. , Pilas Begue A. , Louvel L. , Rols J. L.
Published: May 2018

With new EC regulations, alternative treatment and disposal techniques of the excess sludge produced by activated sludge wastewater treatment plants have to be developed. To decrease activated sludge production yield, microbial cell lysis can be amplified to enhance cryptic growth (biomass growth on lysates). Cell breakage techniques (thermal, alkaline and a combination) were studied to generate Ralstonia eutropha (strain model) and waste activated sludge lysates and to evaluate their biodegradability. Gentle treatment conditions by alkaline waste treatment (20 min at 60°C and pH 10 by NaOH addition) allowed waste activated sludge to be solubilized by a two step process (instantaneous and post-treatment) giving a dissolved organic carbon released by the total suspended solids treated of 267 mgDOC.g-1TSS. The biodegradation of the soluble fraction of the lysates by fresh sludge reached 75 and 90% after 48 and 350 hrs of incubation respectively. A validation on a laboratory scale by insertion of a liquor alkaline heat treatment loop in a biological synthetic wastewater treatment process was carried out. A reduction of 37% of the excess sludge was obtained without altering the purification yield of the process.
State of the art for animal wastewater treatment in constructed wetlands
Authors: Hunt P.G. , Poach M.E.
Published: May 2018

Although confined animal production generates enormous per-unit-area quantities of waste, wastewater from dairy and swine operations has been successfully treated in constructed wetlands. However, solids removal prior to wetland treatment is essential for long-term functionality. Plants are an integral part of wetlands; cattails and bulrushes are commonly used in constructed wetlands for nutrient uptake, surface area, and oxygen transport to sediment. Improved oxidation and nitrification may also be obtained by the use of the open water of marsh-pond-marsh designed wetlands. Wetlands normally have sufficient denitrifying population to produce enzymes, carbon to provide microbial energy, and anaerobic conditions to promote denitrification. However, the anaerobic conditions of wetland sediments limit the rate of nitrification. Thus, denitrification of animal wastewaters in wetlands is generally nitrate-limited. Wetlands are also helpful in reducing pathogen microorganisms. On the other hand, phosphorus removal is somewhat limited by the anaerobic conditions of wetlands. Therefore, when very high mass removals of nitrogen and phosphorus are required, pre- or in-wetland procedures that promote oxidation are needed to increase treatment efficiency. Such procedures offer potential for enhanced constructed wetland treatment of animal wastewater.
The Everglades Nutrient Removal Project test cells: STA optimization - status of the research at the north site
Authors: Majer Newman J. , Lynch T.
Published: May 2018

The Everglades is an oligotrophic ecosystem that is being adversely impacted by hydrologic changes and nutrient-rich runoff generated from urban and agricultural sources. The Stormwater Treatment Area (STA) Optimization Research and Monitoring program is mandated by the 1994 Everglades Forever Act and will assist the South Florida Water Management District in developing operational strategies that maximize performance of emergent macrophyte STAs. The primary objective of this research is to examine how hydrologic conditions may influence STA performance. The study was conducted in 0.2 ha, shallow, fully lined test cells located within the perimeter of the Everglades Nutrient Removal Project. Experiments were designed to examine the effect of increased and decreased hydraulic loading rate (HLR) on wetland performance and to determine, if possible, the HLR at which STA treatment fails to reduce outflow total phosphorus concentration to the interim target of 50 μg-P/L. To date, two HLR experiments have been completed at the north site. Preliminary data indicated at all HLRs tested that particulate phosphorus and dissolved organic phosphorus ratios remained virtually unchanged from inflow to outflow. The dissolved organic and particulate compounds within these test cells are extremely recalcitrant, and are not easily assimilated within the system. High HLRs may not result in detention times long enough to mineralize these forms into easily assimilated inorganic compounds, resulting in mean TP concentrations greater than 50 μg-P/L.
Protozoan predation as a mechanism for the removal of cryptosporidium oocysts from wastewaters in constructed wetlands
Authors: Stott R. , May E. , Matsushita E. , Warren A.
Published: May 2018

The removal of the protozoan parasite, Cryptosporidium parvum, from wastewaters is becoming of increasing importance in the UK, especially since contamination of raw waters by sewage effluents has been implicated in major waterborne outbreaks of cryptosporidiosis in recent years. Compared to conventional wastewater-treatment processes, constructed wetlands have demonstrated favourable removal rates for Cryptosporidium oocysts. The removal mechanisms, however, remain unknown. Predation by free-living ciliated protozoa, which are commonly found in constructed wetlands, was investigated as a possible mechanism for oocyst removal. In laboratory feeding experiments, ciliates (Euplotes patella, Stylonychia mytilus, Paramecium caudatum and an unidentified wetland ciliate species), were exposed to doses ranging from 10 to 106 oocysts/ml for between 5 and 60 minutes. Ciliate predatory activities were assessed by enumerating fluorescently labelled ingested oocysts using epifluorescence microscopy. Oocysts were found to be ingested by all species investigated. Paramecium demonstrated the highest mean ingestion rates (up to 170 oocysts/hr) followed by Stylonychia (up to 60 oocysts/hour). Euplotes and the wetland ciliate had lower mean grazing rates (4 and 10 oocysts/hr respectively). These results indicate that protozoan predation may be an important factor in the removal of Cryptosporidium oocysts from wastewaters in constructed wetlands.
Bacterial dynamics in the sub-surface constructed wetland
Authors: Vymazal J. , Balcarová J. , Doušová H.
Published: May 2018

Constructed wetlands have been shown to be capable of removing a wide variety of contaminants, including bacterial pollution. However, only limited information exists on the distribution of bacteria on roots of macrophytes growing in constructed wetlands. Constructed wetland with sub-surface horizontal flow at Nucÿice near Prague, Czech Republic, was put in operation in 1996. The system treats municipal sewage from 650 PE and the total area of the beds, planted with Phalaris arundinacea and Phragmites australis in alternate stripes perpendicular to the flow direction, is 3,224 m2 (2 beds 62×26 m each). Pea gravel (8/16 mm) was used as a filtration material. During the period 1998-1999, distribution of total aerobic and anaerobic bacteria, coliform bacteria and fecal streptococci was monitored in wastewater as well as on roots of both macrophyte species. Counts of bacteria on root surface in the system at Nucÿice indicate that there is a steep decrease in bacterial numbers within the first few metres of the bed and that there is significantly more bacteria on roots of Phragmites as compared to Phalaris. There was no statistically significant influence of the season on the bacterial counts on roots of macrophytes.
The influence of water table fluctuations on nutrient dynamics in the rhizosphere of common reed (Phragmites australis)
Authors: Urbanc-Berčič O. , Gaberščik A.
Published: May 2018

Lake Cerknisÿko jezero is an intermittent lake and thus it is an ecosystem with permanent water level fluctuations. The lake area is covered mainly by wetland vegetation, with a common reed (phragmites australis) as the prevailing species. The present research evaluated the influence of water table fluctuations on nutrient dynamics in the root zone of the reed. The content of nutrients (nitrate, nitrite, ammonium, soluble phosphorus) was monitored in the pore water, using ground samplers. The vitality of roots was determined measuring terminal electron transport (ETS) activity of root tissue on the vertical profile of the root system. The content of organic matter ranged from 33% up to 48% on a soil depth profile of 1 m. During the year nutrients were present on the whole profile. Water table fluctuations influenced the form, concentration and availability of nutrients in pore water and the vitality of roots. The measurements of potential respiration of root tissue (ETS activity) revealed the highest vitality in the upper layer of the rhizosphere.
Residential subsurface flow treatment wetlands in northern Minnesota
Authors: Axler R. , Henneck J. , McCarthy B.
Published: May 2018

Approximately 30% of Minnesotans use on-site systems (~500,000 residences) and >50% are failing or non-compliant with regulations due to restrictive soils and site conditions. Many sites occur near lakes and streams creating health hazards and deteriorating water quality. SSF CWs have been evaluated year-round at two northern sites since 1995. The NERCC CWs simulate single homes and the Grand Lake demonstration CW treats STE from a cluster of 9 lakeshore homes. Systems were generally able to achieve design criteria of 25 mgTSS/L and 30 mgBOD5/L and the NERCC CWs required only 0.3m of unsaturated soil to achieve consistent disinfection to <200 fecals/100 mL year round. Seeding experiments with Salmonella indicated removal efficiencies of 99.8% in summer and 95% in winter. High strength (∼300 mgBOD/L, 95 mgTN/L) influent at NERCC probably limited system performance, particularly N-removal (mass) which was ∼42% in summer and 20% in winter. The data indicate CW's are a viable, year-round treatment option for homeowners in terms of performance, ease of operation, and cost but require additional maintenance related to inconsistent vegetation growth, winter insulation, and meeting concentration-based regulatory standards since they were seasonally and annually variable due to rain events, partial freezing, spring snowmelt, and summer evapotranspiration.
Constructed wetlands for wastewater treatment in the Czech Republic
Authors: Vymazal J.
Published: May 2018

The first constructed wetland (CW) for wastewater treatment was built in the Czech Republic in 1989. This recent survey shows that at the end of 1999 101 systems are in operation and several more are under construction. 95 CWs are designed with sub-surface horizontal flow, 6 systems are hybrid with a combination of vertical and horizontal flow beds. Most systems (56) were designed for the treatment of municipal and domestic sewage while 38 CWs were designed for the treatment of wastewater from combined sewer systems. The most commonly used size of vegetated beds is 1,001-2,500 m2 (31 systems) followed by the area between 51-250 m2 (19%). The area of vegetated bed of the largest system is 4,493 m2. Size distribution is quite evenly spread from very small systems (PE = 3 or 4) up to 1,000 PE. However, most systems (44) were sized to treat wastewater from sources between 101 and 500 PE. The most commonly used macrophyte is Common reed (Phragmites australis) which is used in 34 systems as a monotypic stand and in 44 systems in combination with other macrophytes, most frequently with Reed canarygrass (Phalaris arundinacea) (31 systems) and cattails (Typha spp.) (8 systems).
Design and performance of experimental constructed wetlands treating coke plant effluents
Authors: Jardinier N. , Blake G. , Mauchamp A. , Merlin G.
Published: May 2018

Reed beds were chosen to treat effluents from a coke plant in France (Usinor-Sollac, Fos/mer). The pilot is composed by a two-stage gravel bed with subsurface flow and Phragmites australis as plant. This experimental constructed wetland was monitored for one year at steady-state conditions. The composition of influent shows high concentrations of organic compounds. The hydraulic residence time was close to 10-12 days with a plug flow with longitudinal dispersion. Results show that global removal of nitrogen ranged from 54 to 94% of load removal efficiency, but corresponds easily to the regulation recommendations. Because of wintertime, the denitrification process was inhibited by aerobic conditions observed in the gravel bed with oxygen concentrations higher than 2-3 mg/L, and by small amounts of biodegradable carbon. The fate of mineral pollutants are linked to the complex ferric hydroxides balance and a lack of phosphorus was observed for reed plants, as this nutrient is dependent on iron compounds. Some necrosis was observed on plant tissues corresponding with anthocyanic pigments accumulation caused by phosphorus absorption deficiency due to its co-precipitation with iron.
Influence of load distribution and recycle rate in step-fed facultative ponds
Authors: Sambuco J.P. , da Costa R.H.R. , Paing J. , Picot B.
Published: May 2018

This study presents the results of research on a wastewater treatment system with four identical facultative ponds in series with step-feeding and recirculation (SFFPR). Four modes of distribution of the influent were studied, which were (in percentages of the inflow per pond): C1 = 25/25/25/25; C2 = 50/20/20/10; C3 = 50/50/0/0; C4 = 100/0/0/0. The organic loading applied to the four ponds overall was around 200 kg BOD5/ha.d. The distribution C4 = 100/0/0/0 was selected for studying the recycle rate. Three recycling rates were studied: 0.5Q, 1Q and 2Q. COD and BOD5 removal efficiencies were high whatever the step-feed distribution. For the distribution C1 and C2, the four ponds were homogeneous. The equal distribution of organic loading rate in C2 distribution was most beneficial for algal growth. For piston pattern distributions (C3 and C4), the ponds receiving the highest loading showed a bacterial biomass higher than that of the primary production. Increasing the recirculation rate seemed to lead towards homogenisation of the ponds, while a decrease appeared to lead to their individualisation and increased their productivity. The SFFPR constitutes a stage of the treatment process which can replace the facultative stage; it produces a high effluent quality and decreases land area requirements.
The effect of topography, season and weather situation on daily precipitation gradients in 60 Swiss valleys
Authors: Sevruk B. , Mieglitz K.
Published: May 2018

Daily precipitation in the Swiss valleys decreases frequently with altitude, particularly in southern Switzerland. Only one-third of precipitation days show positive precipitation gradients with a fairly strong correlation of precipitation with altitude (R2≥0.5). Generally, precipitation gradients are larger in the north than in the south but there are large differences among valleys situated near to each other. The effects of precipitation amount, weather situation, region and season, wind speed and topography were not very significant at all. It seems that the positioning of the upper and lower precipitation gauges under specific topographic and climate conditions can affect the precipitation gradients in a particular valley.
Investigating the changes in extreme rainfall series recorded in an urbanised area
Authors: Aronica G. , Cannarozzo M. , Noto L.
Published: May 2018

The aim of this study is to investigate and quantify changes in the rainfall regime of the metropolitan area of Palermo characterised by increasingly strong urbanisation. The rainfall data, considered in this study, were collected on a yearly basis from eight rain gauges within and outside the metropolitan area of Palermo, Sicily, Italy. A preliminary analysis made on the annual total rainfall depths showed a global reduction of total annual rainfall, with two different trends: more regular for the series observed in the rain gauges within the urbanised area and more variable for the series observed in the rain gauges outside the area. A further analysis has been performed using the series of maximum intensity for fixed duration (1, 3, 6, 12, 24 hrs) and annual daily maxima. The analysis of the trend in the extreme rainfall series has been performed by estimating the maximum rainfall depth corresponding to a fixed return period using the EV1 distribution with parameters estimated using L-moments. The analysis of all series indicates a global reduction of rainfall intensities, both for internal and external series, in disagreement with the results obtained by other authors.
IDAF (intensity-duration-area frequency) curves of extreme storm rainfall: a scaling approach
Authors: De Michele C. , Kottegoda N.T. , Rosso R.
Published: May 2018

Intensity-duration-area frequency curves, IDAF, are determined for the evaluation of design storms using a scaling approach. The variability of maximum annual rainfall intensity in area and duration is represented through the scaling properties in time and space. Thus the scaling relationships of mean rainfall intensity with area and duration are derived using the concepts of dynamic scaling and statistical self-affinity. For a lognormal distribution of rainfall intensity a multiscaling lognormal model is obtained. This gives the IDAF curves of extreme storm rainfall. An application is made to the metropolitan area of Milano.
A Markov modulated Poisson process model for rainfall increments
Authors: Onof C. , Yameundjeu B. , Paoli J.-P. , Ramesh N.
Published: May 2018

The problems encountered when using traditional rectangular pulse hierarchical point process models for fine temporal resolution and the growing number of available tip-time records suggest that rainfall increments from tipping-bucket gauges be modelled directly. Poisson processes are used with an arrival rate modulated by a Markov chain in continuous time. The paper shows how, by using two or three states for this chain, much of the structure of the rainfall intensity distribution and the wet/dry sequences can be represented for time-scales as small as 5 minutes.
An enquiry into rainfall data measurement and processing for model use in urban hydrology
Authors: Einfalt T. , Arnbjerg-Nielsen K. , Spies S.
Published: May 2018

Rain data are collected all over the world because water is of paramount importance to all human life. WMO has provided standards for collection and standardized data processing of daily rainfall measurements. Currently no such standards are available for gauges with a resolution suitable for urban hydrology, where the resolution in time must not exceed a few minutes. The Group on Urban Rainfall under the International Water Association has made a comparison of national standards by means of a survey of 77 questions sent to 44 countries. The paper discusses the first results of the answers of the survey. Currently tipping bucket gauges are the dominating method of obtaining high resolution rain data, but the numbers of weighing gauges and radar measurements are rapidly growing. It is necessary to try to increase the awareness of documentation of current standards and to agree on standards for measurements and data processing on an international level in the future.
River Pollution Diagnostic System (RPDS) - computer-based analysis and visualisation for bio-monitoring data
Authors: O'Connor M.A. , Walley W.J.
Published: May 2018

The importance of biological monitoring for the assessment of river quality is well established. Bio-monitoring programmes, in particular the recording of benthic macroinvertebrate assemblages, produce an abundance of data to support the process of river quality assessment. However, current data analysis techniques are largely based on subjective score systems that do not fully realise the potential information value of such complex multivariate data sets. More advanced techniques of data analysis and visualisation can help to maximise the value of biological data, and hence to more efficiently and effectively direct resources, funding and research. A River Pollution Diagnostic System (RPDS) is described. RPDS was recently developed by the authors for the Environment Agency in England and Wales; it aims to maximise information retrieval from biological and environmental data.
A kinetic model of N-nitrosodimethylamine (NDMA) formation during water chlorination/chloramination
Authors: Choi J. , Valentine R.L.
Published: May 2018

Experiments were conducted to investigate the hypothesis that N-nitrosodimethylamine (NDMA) is a potential disinfection by-product. NDMA was formed by the reaction of dimethylamine (DMA) with monochloramine and also with free chlorine in the presence of ammonia. We proposed a mechanism for NDMA formation which does not require the presence of nitrite as in N-nitrosation. The critical NDMA formation reactions consist of i) the formation of monochloramine by combination of free chlorine with ammonia, ii) the formation of 1,1-dimethylhydrazine (UDMH) intermediate from the reaction of DMA with monochloramine followed by, iii) the oxidation of UDMH by monochloramine to NDMA, and iv) the reversible chlorine transfer reaction between free chlorine/monochloramine and DMA which is parallel with i) and ii). A kinetic model was developed to validate the proposed mechanism.
From municipal sewage to drinking water: fate and removal of pharmaceutical residues in the aquatic environment in urban areas
Authors: Heberer Th. , Reddersen K. , Mechlinski A.
Published: May 2018

Recently, the occurrence and fate of pharmaceutically active compounds (PhACs) in the aquatic environment was recognized as one of the emerging issues in environmental chemistry and as a matter of public concern. Residues of PhACs have been found as contaminants in sewage, surface, and ground- and drinking water samples.

Since June 2000, a new long-term monitoring program of sewage, surface, ground- and drinking water has been carried out in Berlin, Germany. Samples, collected periodically from selected sites in the Berlin area, are investigated for residues of PhACs and related contaminants. The purpose of this monitoring is to investigate these compounds over a long time period to get more reliable data on their occurrence and fate in the different aquatic compartments. Moreover, the surface water investigations allow the calculation of season-dependent contaminant loads in the Berlin waters. In the course of the monitoring program, PhACs and some other polar compounds were detected at concentrations up to the μg/L-level in all compartments of the Berlin water cycle. The monitoring is accompanied and supported by several other investigations such as laboratory column experiments and studies on bank filtration and drinking water treatment using conventional or membrane filtration techniques.
Online-simulation of the WWTP to minimise the total emission of WWTP and sewer system
Authors: Seggelke K. , Rosenwinkel K.-H.
Published: May 2018

In this paper, the application of a WWTP-Online-Simulation with the objective to reduce the total emission into the receiving waters is explained. Apart from an introduction and a short description of the possible reduction potentials, first results of the current research project (financed by the German ministry BMBF) are presented. Results of the pilot plant with different experiments of increased stormwater inflow than usual and different control strategies showed the possibility to treat stormwater up to the quadruple dry-weather flow while still meeting the effluent values. However, this is not always guaranteed, and thus a monitoring system with integrated control strategies which is adapted to the load case “stormwater” with prognosis load cases becomes necessary. In the presented example, the simulation (Activated Sludge Model 2d) achieved an excellent match with the measured effluent values of the aeration tank (NH4-N, NO3-N) over a period of several months. The most important prerequisites for good (online-) simulation results are the exact knowledge of the plant and the plausibility and alternative concepts for the measured values in case of sensor failure.
The effect of extended in-sewer storage on wastewater treatment plant performance
Authors: Ashley R.M. , Dudley J. , Vollertsen J. , Saul A. , Jack A. , Blanksby J.R.
Published: May 2018

A project funded by UKWIR is under way in the UK to develop a relatively simple methodology whereby the effects of the introduction of extended in-sewer storage at CSOs on downstream sewerage and treatment can be assessed. Recent legislation (UK and European) has compelled many sewer system operators to introduce systems which increase in-sewer retention times, and also retain more flow and load within sewer networks. The project has reviewed existing knowledge about the interaction between in-sewer flow and treatment plants, together with available models. The study is utilising a “benchmark” of 3 configurations of treatment plant and dynamic simulation using the WRc STOAT software, with minor modifications to ensure that effects on odour generation and nutrient removal processes are adequately modelled. As no existing sewer flow quality model can represent the range of conditions possible in sewer networks, a combined application of the Hydroworks model and a new model developed at Aalborg University is being used for this part of the study.
Oligonucleotide probe hybridization and modeling results suggest that populations consuming readily degradable substrate have high cellular RNA levels
Authors: Frigon D. , Oerther D.B. , Morgenroth E. , Raskin L.
Published: May 2018

Analyses based on ribosomal RNA (rRNA)-targeted hybridization performed in our laboratory identified two types of bacterial populations: a population with a high RNA level per biomass and a population with a low level of RNA per biomass. To extend these descriptions, the diurnal dynamics of the RNA pool were monitored by rRNA-targeted oligonucleotide probe membrane hybridization. Under the typical diurnal variation in COD loading rate experienced by municipal wastewater treatment plants, the RNA level of the bacterial population with a high level of RNA per biomass varied with changes in the COD loading rate. Under the same conditions, the RNA level of the population with low RNA level per biomass remained constant. A structured biomass model was developed to describe these data. Substrate COD was divided into a readily biodegradable and a slowly biodegradable COD fraction. It was assumed that two specialized populations coexist in municipal activated sludge treatment systems. One population consumes readily degradable COD and the other consumes slowly degradable COD. According to model simulations, the population consuming readily degradable COD has a high level of RNA per biomass under variable substrate concentrations. Comparatively, the population consuming slowly degradable COD has a low level of RNA level per biomass. Furthermore, model simulations reproduced the two diurnal RNA profiles observed in a full-scale municipal activated sludge system. Therefore, we suggest that two populations can be distinguished in municipal activated sludge systems: a population consuming readily degradable substrate and a population consuming slowly degradable substrate.
Effect of different carbon sources on aerobic storage by activated sludge
Authors: Beccari M. , Dionisi D. , Giuliani A. , Majone M. , Ramadori R.
Published: May 2018

A study of substrate removal by real activated sludge with several synthetic substrates (acetate, ethanol, glutamic acid) and wastewater (raw and filtered) was carried out. Substrate, stored compounds (polyhydroxyalkanoates, PHA and internal carbohydrates), ammonia and oxygen uptake rate (OUR) were analytically determined. Polyhydroxybutyrate (PHB) was stored when the substrate was acetate or ethanol, while no appreciable formation of storage compound was detected using glutamic acid. A low amount of PHB was also formed in tests with raw and filtered wastewater which was probably mainly due to its acetate content. As far as the sum of storage and growth (indirectly estimated through ammonia consumption) did not match the overall solids formation, other unidentified mechanisms of substrate removal were likely to occur (biosorption, accumulation and/or storage of unidentified compounds). ASM3 and two derived models were used in the interpretation of experimental data with reference to synthetic substrates. With reference to synthetic substrates ASM3 can well describe the experimental data only assuming a stored product formation much higher than the analytically detected one, whereas the model that assumes a parallel growth and storage on the substrate can well describe the observed stored product profile only assuming a direct contribution of growth much higher than estimated from ammonia consumption. The model that assumes an accumulation/biosorption stage as first step of substrate removal can better describe the whole experimentally observed behaviour. However as well as in ASM3 this implies that some fraction of removed COD is still unidentified. With reference to real wastewater where the different phenomena were mixed up due to the presence of several substrates, the different models gave similar results.
Experience and extensions to the ASM2 family of models
Authors: Dudley J. , Buck G. , Ashley R. , Jack A.
Published: May 2018

The development of ASM2 has created a complex model for biological phosphorus removal. Most of the published work on calibrating this model has focused on the design of experiments to maximise information with which to calibrate the model, or the use of hourly data collected around and within an aeration tank. But many sewage works do not collect such data, nor have such instrumentation. The application of ASM2 with sparse data collected at a low frequency, and mostly only input-output, is considered in this paper, based on data collected at a Swedish sewage works. This paper shows that ASM2 can be calibrated with such measurements.

This paper also looks at a modification to ASM2d to better handle heterotrophic usage of volatile fatty acids, and the use of this model to study the effects of large increases in in-sewer storage on sewage treatment works. Concern about the generation of large quantities of VFAs, and their effect on the sewage treatment processes, was unfounded.
Infiltration and inflow in combined sewer systems: long-term analysis
Authors: Weiß G. , Brombach H. , Haller B.
Published: May 2018

A study was conducted on 34 German combined sewer systems including combined sewer overflow (CSO) tanks and treatment plant to show up actual hidden reserves and bottlenecks in stormwater treatment. The study gave also a general insight into the water pathways in urban hydrology. A special focus was given to undesired non-polluted water infiltrating into the sewer, labelled infiltration and inflow (I/I) or infiltration inflows, which is widely underestimated. It leads to a bad performance of the drainage system although the parasite waters are themselves non-polluted. In existing combined systems, pollution control can be considerably improved by reducing I/I. It is equivalent to the reduction of surface runoff e.g. by a separate drainage as frequently proposed alternative. Artificial infiltration of surface runoff may even increase infiltration inflows.
Developments in a methodology for the design of engineered invert traps in combined sewer systems
Authors: Buxton A. , Tait S. , Stovin V. , Saul A.
Published: May 2018

Sediments within sewers can have a significant effect on the operation of the sewer system and on the surrounding natural and urban environment. One possible method for the management of sewer sediments is the use of slotted invert traps. Although invert traps can be used to selectively trap only inorganic bedload material, little is known with regard to the design of these structures. This paper presents results from a laboratory investigation comparing the trapping performance of three slot size configurations of a laboratory-scale invert trap. The paper also presents comparative results from a two-dimensional computational model utilising stochastic particle tracking. This investigation shows that particle tracking consistently over-predicts sediment retention efficiencies observed within the laboratory model.
Application of eutrophication indices for assessment of the Bulgarian Black Sea coastal ecosystem ecological quality
Authors: Moncheva S. , Dontcheva V. , Shtereva G. , Kamburska L. , Malej A. , Gorinstein S.
Published: May 2018

The present paper is an attempt to test the applicability of the trophic state index (TRIX) for scaling the eutrophication along the Bulgarian Black Sea coastal zone in concert with a number of chemical and biological descriptors aimed at selection of relevant indicators of marine coastal area ecological quality. The following environmental parameters have been considered: to, salinity, nutrients - inorganic P, N and dissolved Si, dissolved oxygen and oxygen saturation, phytoplankton - taxonomic structure, abundance and biomass, chlorophyll a, zooplankton - taxonomic structure, abundance and biomass. Principal Component Analysis was applied in order to figure out and score the most relevant combination of parameters to discriminate between sites and select representative descriptors (pressure/state) of eutrophication. The following variables are defined as relevant descriptors for classification of the sites: nutrients (N, P, Si) and their molar ratios (N:P and Si:P), the capacity of the system to produce and sustain organic matter (chlorophyll a, phytoplankton biomass), phytoplankton taxonomic dominance (Bacilariophyceae:Dinophyceae biomass ratio), grazing pressure (phytoplankton:zooplankton biomass, Bacilariophyceae:Copepoda), plankton diversity index (Hb and Ha) and the trophic state index (TRIX). The investigated sites under a different anthropogenic impact are classified according to selected descriptors and their water quality state.
Rehabilitation and water quality monitoring in the Golden Horn
Authors: Sur H.I. , Okuş E. , Sarikaya H.Z. , Altiok H. , Eroğlu V. , Öztürk I.
Published: May 2018

In this work, the oceanographic aspects of the Golden Horn and some results of the Golden Horn Rehabilitation Project are presented. The hydrographic structure of the Golden Horn responds rapidly to the conditions in the southern Bosphorus, which is especially true for the outer parts of the estuary up to the Valide Sultan Bridge (VS). West of this bridge which was blocked by the pontoons of the bridge, carries the major pollution load and is dependent on the underlying water and surface mixing, for its renewal. The dissolved oxygen concentrations were measured below the detection limit in the region between the VS and Eyüp-Sütlüce (ES) section during the majority of the measurement periods where H2S has been determined simultaneously until February 2000. Although the microbial contamination of the estuary stations is very high, decreases in the contamination at stations are observed. The highest concentrations are recorded at the ES-VS section and supported by Fecal Coliform data during the rainy months in general despite the operational collector system surrounding the estuary. An obvious decrease of pollution in comparison with the data of the previous years is clearly observed as an encouraging result of the rehabilitation efforts achieved so far.
Benthic community structure of the Bosphorus and surrounding area
Authors: Uysal A. , Yüksek A. , Okuş E. , Yilmaz N.
Published: May 2018

Spatial and temporal distribution of benthic communities around the Strait of Istanbul (Bosphorus) and the effect of lower layer discharge on these communities have been evaluated during studies between FebruaryÐDecember 1999. Mytilus galloprovincialis was the dominant species with fasies at the Black Sea station that is not affected by the strait lower layer current system. On the other hand, another Black Sea station, influenced by the strait lower layer currents, has a similar biota to the strait stations. Species richness and diversity is highest in the strait than other areas. The dominant species is Maera grossimana. However, the station located at the Black Sea exit of the strait has a different biota, and various groups/species appeared to be dominant. Melinna palmata is the dominant species at the Sea of Marmara during the study period. Low dissolved oxygen values of lower layer and soft substratum of sediment resulted in wide distribution of Melinna palmata, adapted to these conditions. The closer stations to the strait in the Sea of Marmara have higher diversity as a result of hydrodynamic processes. On the other hand, coastal stations with low currents and inputs have lower index values, showing the negative effect of discharges and pollution.