bluuebunny/crossref_metadata_2025 huggingface dataset:
A statistical approach to pollutant emissions from combined sewer systems
Authors: Veldkamp Robin G. , Wiggers Jan B. M.
Published: May 2018

This research is based on CSO emissions from Dutch sewer systems. During the years 1982 to 1989 research was done on several sewer systems, all of them equiped with a single overflow weir. Pollutant emissions were calculated from the measurements, whereby each storm was considered as a single event. Extreme emissions have a detrimental, sometimes even desastrous effect on water quality. Such extreme emissions are the result of heavy storms, giving it a low frequency of occurrence. From the measurements a statistical model was developed enabling the user to forecast extreme waste emissions with a certain return period in a range of 2 to 10 years. Five pollutants are put in the model: BOD, COD, Kjeldahl nitrogen, total phosphate and suspended solids. The model operates with standardized emission values in kg per ha of impervious area. When the model is used in practice the runoff area to the specific overflow under consideration has to be known.
The underlying structure of systematic variations in the event mean concentrations of pollutants in urban runoff
Authors: Grum M. , Aalderink R. H. , Lijklema L. , Spliid H.
Published: May 2018

Urban runoff pollution can essentially be characterised by fluid quantities and pollutant concentrations. It has been possible to construct models accounting for variations in runoff quantities with some success. However, although several pollutant storage and transport mechanisms have been postulated there still remains substantial unexplained variation in pollutant concentrations. Through a series of well established multivariate pattern recognition techniques the present study has aimed at disclosing the underlying structure of systematic variations in the event mean concentrations (EMC) of pollutants in combined sewers during rainfall. The statistical methods that have been applied to the pollutant concentration variables are factor analysis, cluster analysis, distribution analysis and correlation analysis. The event mean runoff data considered includes eleven pollutant variables originating from five combined sewer catchments in Denmark and in the Netherlands. The combined results of the analyses support earlier findings that EMCs are best described by bimodal or mixture distributions, and further suggest that event based pollutant modelling could be improved through a recognition of these characteristics.
Distribution of nitrifying bacteria in a shallow stream
Authors: Jancarkova Ivana , Larsen Tove A. , Gujer Willi
Published: May 2018

A project investigating the dynamics of self-purification processes in a shallow stream is carried out. Effects of the concentration gradient due to the distance to the pollution source, of hydraulic conditions in the river bed and of storm floods on the distribution of nitrifying bacteria were studied with the help of laboratory and field experiments. Nitrifiers density on the surface of the stream bed increased rapidly up to a distance of 300 m from the WWTP indicating possible competition of the nitrifiers with the heterotrophic bacteria close to the WWTP. Afterwards a slight decrease in the downstream direction was observed. In vertical profiles, higher bacterial densities were found at sites with rapid infiltration of channel water to the stream bed than at sites with no exchange between channel water and stream bed water or where stream bed water exfiltrated. A major flood event scoured the nitrifiers nearly totally from the surface of the river bed. Major floods belong so to the most dominant processes controlling self-purification in shallow streams. Minor floods, however, don't scour bacteria in the depth of the stream bed that could then be important for the self-purification processes.
The impacts of discharges from two combined sewer overflows on the water quality of an urban watercourse
Authors: Mulliss R. , Revitt D. M. , Shutes R. B. E.
Published: May 2018

The impacts of combined sewer overflows and surface water outfalls on receiving water quality are assessed by comparing dry weather flow and storm event concentrations of dissolved oxygen, BOD, total and unionised ammonia, pH, dissolved copper and total zinc with those recommended by the River Ecosystem classification guidelines for freshwaters in the UK. The deteriorating conditions during wet weather are identified by water quality falling below the RE2 category for all monitored pollutants, other than dissolved copper, and reaching the most grossly polluted condition for BOD and total ammonia.
Deriving discharge strategies to reduce CSO in urban drainage systems
Authors: Breur K.-J. , van Leeuwen P. E. R. M. , Dellaert N. P.
Published: May 2018

This paper discusses the design of discharge strategies for urban drainage operation. The design procedure applies a tuneable strategy which can be adjusted to a specific situation by adjusting a few parameters which reflect the discharge priority of the various districts of the system. The actual design procedure, a procedure of simulation and analysis of the system performance, is explained in a case study. Apart form the method, the case study shows that a near optimal performance (maximum reduction of overflow volume) can be realised by applying an “event” average strategy (one strategy for all type of inflow events). Furthermore, the case study shows that the major part of the total overflow volume is caused by very heavy storm events.
Alternative stormwater management concept for urban and suburban areas
Authors: Huhn V. , Stecker A.
Published: May 2018

In the investigation areas a conventional stormwater discharge system cannot be realized. Therefore alternative stormwater drainage systems are planned whose drainage conditions are very similar to those of an undeveloped area. Most of the expected stormwater discharge can be infiltrated into the soil. This means that the system keeps the water in the hydrological cycle. The alternative systems also leads to economical advantages.
Ways to get water: rainwater utilization or long-distance water supply? A holistic assessment
Authors: Herrmann Thilo , Hasse Karin
Published: May 2018

On the basis of a case study the costs of an existing long-distance drinking water supply system are compared to the potentiel costs of decentralized rainwater collection und usage systems. The costs of stormwater retention are included in the calculations in so far as rainwater utilization systems provide a retention capacity for stormwater in the cisterns. The results show, that in dependence of the market price of the rainwater usage systems, the decentral way to provide usage water to the households can be more cost effective compared to a central long-distance supply system.
Model based real-time control of sewer system using fuzzy-logic
Authors: Fuchs L. , Beeneken T. , Spönemann P. , Scheffer C.
Published: May 2018

This paper describes the use of the sewer model HYSTEM-EXTRAN in combination with a rule based control device using fuzzy-logic to simulate the real-time control of a sewer system. The rules for the control of the system were set up with the help of optimization procedures. The advantage of the procedure is proved by comparing the uncontrolled versus the controlled state in a simulated mode for an existing sewer system. The final system was installed and tested within the sewer system.
A study on the effects of urban runoff controls in the sandsli research catchment, Bergen, Norway
Authors: Thorolfsson Sveinn T.
Published: May 2018

This paper describes a case study on a new alternative drainage system for urban stormwater management, the so-called “Sandsli-system”. The aim of this study is to evaluate the Sandsli system and the effects of the solution on ground water conditions. The study is carried out in the Sandsli research catchment in Bergen, Norway. The idea behind the “Sandsli-system is not to mix the polluted and the clean stormwater combined with a source control for both stormwater quantity and quality. The clean stormwater is percolated as quickly as possible, while the polluted stormwater is collected and conducted to an appropriate site for disposal or treatment.

The Sandsli-system was developed as an alternative drainage system to the conventional drainage system. The system has been functioning satisfactorily since 1981 to date. The advantages of the use of the Sandsli-system is highlighted i.e. recharging the stormwater to the ground water. The Sandsli-system is appropriate to locations with climate and geology similar to that found in the coastal part of Norway
Field facility for research and demonstration of CSO treatment technologies
Authors: Averill D. , Mack-Mumford D. , Marsalek J. , Andoh R. , Weatherbe D.
Published: May 2018

A pilot scale study of options for the treatment combined sewer overflows is being conducted in Ontario, Canada. The objective is to achieve primary clarification equivalency in simple, high-rate satellite treatment systems. Effluent disinfection will also be required where bathing beaches are to be protected. Long column settling tests conducted with CSO suspensions indicated that approximately 40% of the suspended solids was non-settleable at the test threshold of 0.3 m/h. The use of a cationic polymer as the sole coagulant in a three metre diameter vortex separator achieved at least 50% TSS removal at surface loads up to approximately 40 m/h. The effluents from solid/liquid separation operations using the polymer coagulation strategy were more amenable to UV disinfection than those produced with metal-based coagulants. This document has been updated to include experimental results to mid-1997.
Waterborne Campylobacter in Sweden: the cost of an outbreak
Authors: Andersson Y. , de Jong B. , Studahl A.
Published: May 2018

Outbreaks of waterborne disease happen in Sweden, as in most other countries. During the period 1980-1995, a total of 90 outbreaks were reported, involving about 50,000 sick people and two deaths. About 80% of the outbreaks are caused by unknown agents but Campylobacter is the most common agent. Between 1980 and 1995, 11 campylobacteriosis outbreaks were reported, three of which had 1,000->3,000 sick people involved. These waterborne outbreaks cost society, the water-treatment plant involved and the sick person a lot of money. A waterborne outbreak also raises the question whether people can have confidence in the community tap water.
Assessment of a water filtration device for household use in rural communities in Mexico
Authors: Galván M. , de Victorica J.
Published: May 2018

Epidemiological studies in rural Mexico have shown the role of poor quality water in gastrointestinal disease incidence. This led to the establishment of a program, which included the assessment of inexpensive systems for household treatment of drinking water. We describe the main features of a hand carved stone filter evaluated over 6 months under laboratory conditions and 6 months under household conditions. The filter had a capacity of 5L and an average volume of 18L/d filtered water (the temperature of which was always an average 4°C lower than the influent). Average bacterial removals under laboratory conditions were 98% for total and faecal coliforms (TC, FC), 96% for faecal streptococci (FS), 99% for Pseudomonas aeruginosa and 100% for helminth eggs and protozoan cysts. During the field evaluation removals were 80–100% TC, 45–95% FC and 8–93% FS due to the different qualities of influent water and the operation conditions. Nevertheless, the filters represented an immediate mitigation measure of the health risks associated with the continuous ingestion of microbiologically unsafe waters.
Silver and hydrogen peroxide as potential drinking water disinfectants: their bactericidal effects and possible modes of action
Authors: Pedahzur R. , Shuval H. I. , Ulitzur S.
Published: May 2018

Silver and hydrogen peroxide (HP) acted synergistically on the viability of E. coli K-12. In certain concentration ranges the synergistic effect amounted to about 3 logs. Toxicity process kinetics were determined by following the decrease in luminescence of a highly luminescent recombinant E. coli harbouring a plasmid carrying the whole lux system of Vibrio fischeri. As in the viability studies, silver and HP also showed a synergistic effect on in vivo luminescence, which amounted to a 2 log increase in toxicity. A similar phenomenon was found for silver and certain metal ions, including Cu2+, Ni2+, Zn2+ and Cd2+, where toxicity increased by a factor of 10 in the presence of sub-inhibitory concentrations of silver. To monitor the expression of different stress response systems in treated cells, we have used E. coli carrying fusions of the lux system to promoters of different stress-controlling genes. Of the fusions tested, HP substantially increased the activity of recA, katG, micF, grpE, lon, and dnaK. Silver exerted a mild effect acting only on grpE and lon promoters. When in combination, a synergistic induction of the dnaK fusion and a slightly additive effect on grpE fusion were recorded. It appears that the combined toxic effect of silver and HP may be related with damage to cellular proteins. Nevertheless, the involvement of other cellular moieties can not be ruled out. The possibility that the synergistic effect is related to chemical interactions between silver and HP and the consequent increase in their toxicity is discussed.
Non-outfall sources of faecal indicator organisms affecting the compliance of coastal waters with directive 76/160/EEC
Authors: Wyer M. D. , O'Neill G. , Kay D. , Crowther J. , Jackson G. , Fewtrell L.
Published: May 2018

The general improvement in UK marine recreational water quality is attributed to the implementation of the EU Directives designed to protect the health of bathers and ensure adequate treatment of urban wastewaters. The effect of this legislation is often to remove the dominant source of faecal indicators which previously masked non-outfall sources. These have the potential to prevent the compliance of identified EU bathing waters with Directive 76/160/EEC standards for faecal coliform bacterial. Detailed investigative methods are outlined which have been employed to identify, quantify and reduce these sources. This problem requires detailed site specific investigation which is expensive when compared to the significant expenditures being committed to sewage treatment.
Bacteriophages are a better indicator of illness rates than bacteria amongst users of a white water course fed by a lowland river
Authors: Lee J. V. , Dawson S. R. , Ward S. , Surman S. B. , Neal K. R.
Published: May 2018

An examination was made of the risk factors for gastrointestinal illness (GI) and other symptoms among canoeists and rafters using an artificial white-water canoe slalom course fed by a lowland river. The investigation was made by carrying out cohort studies of users on several days throughout one year. On each day water samples were collected for the determination of Escherichia coli, enterococci (faecal streptococci), F-specific RNA bacteriophage, sulphite reducing clostridia, culturable enteroviruses and turbidity. Of 755 questionnaires distributed, 473 (63%) were returned. The relative risks of GI and other symptoms were determined by logistic regression analyses. The variables associated with an increased risk of GI-illness were swallowing water, unintentional swimming in the course, eating and drinking before getting changed and the levels of F-specific RNA bacteriophages. Being a regular user was associated with a decreased risk of GI-illness. This study demonstrates the value of F-specific RNA bacteriophages as an index of risk from recreational use of a fresh water environment.
Sunlight wavelengths inactivating faecal indicator microorganisms in waste stabilisation ponds
Authors: Davies-Colley R. J. , Donnison A. M. , Speed D. J.
Published: May 2018

Waste stabilisation ponds (WSPs) are widely used in New Zealand for the treatment of domestic sewage and other organic wastes. Traditionally, faecal coliforms have been used as the faecal indicator in WSPs and their receiving waters but there is increasing interest in alternative indicators. We studied the comparative inactivation kinetics under sunlight of two bacterial indicators in WSP effluent, and also those of two F-specific bacteriophages that may be models of the behaviour of viral pathogens in WSPs. We investigated the wavelength-dependence of sunlight inactivation in rapidly-stirred, small reactors, with temperature, dissolved oxygen and pH control, using various plastics as “longpass” filters to screen different portions of the UV-visible spectrum. The UVB, UVA and blue-green visible radiation (<550nm wavelength) all contributed appreciably to inactivation of enterococci and possibly FRNA phage, consistent with a photooxidation mechanism of action. In contrast, E. coli and presumed FDNA phage were inactivated mainly by UVB, consistent with direct absorption by, and damage to, the DNA with minor or negligible contribution by longer wavelengths. Our results suggest that E. coli may be a better bacterial indicator in WSPs than enterococci.
Microbial growth and assimilable organic carbon in finnish drinking waters
Authors: Miettinen I. , Vartiainen T. , Martikainen P. J.
Published: May 2018

The amount of assimilable organic carbon (AOC) and bacterial regrowth was studied in drinking waters from seven Finnish surface and groundwater works. Bacterial regrowth in drinking waters was studied by in vitro laboratory incubation tests and by enumerating the microbes in distribution networks. Bacterial numbers were counted as heterotrophic viable counts and as total direct counts (AODC). The bacterial production activity was studied as 3H-thymidine uptake. AOC, measured with a bioassay was 390±130mg/l and 170±60mg/l in drinking waters produced from surface waters and from groundwaters respectively. The content of AOC was slightly reduced in distribution pipelines of groundwater works whereas in the distribution pipelines of surface water works it was reduced by 40%. Bacterial regrowth occurred in all drinking waters. Surprisingly, the heterotrophic regrowth was greater in drinking waters produced from groundwaters than in those produced from surface waters. AOC levels correlated poorly with the in vitro bacterial growth tests and with occurrence of bacteria in distribution networks.
Transport of escherichia coli through soil to groundwater traced by randomly amplified polymorphic DNA (RAPD)
Authors: Rothmaier R. , Weidenmann A. , Botzenhart K.
Published: May 2018

Isolates (50) of E. coli obtained from liquid manure (20 bovine, 20 porcine) were genotyped using random amplified polymorphic DNA (RAPD). Typing revealed 9 and 14 different strains in bovine and porcine liquid manure respectively with no strains in common. One porcine strain, showing a simple RAPD pattern, was subcultured and spread on a test field (1.5l/m2 at 1010 cfu/l) in a drinking water protection zone with loamy to sandy sediments in the Donauried area, Baden-Wurttemberg. Soil samples and groundwaters were collected at monthly intervals October 1994 – June 1995 during which 114 E. coli isolates were recovered. The first occurrence and maximum concentration of E. coli in soil samples taken from more than 20cm depth was in January 1995, declining rapidly with depth and time. All isolates from soil and only one from groundwater showed the RAPD pattern of the spread E. coli strain. The results could not demonstrate a severe negative impact of the spreading of liquid manure on the bacteriological quality of the groundwater in the given geological situation. The distinct strain patterns found in different kinds of liquid manure suggest that genotyping of E. coli by RAPD may be an adequate tool for tracing sources of faecal contamination.
Aerobic microbial transformations of resuspended sediments in combined sewers - a conceptual model
Authors: Vollertsen Jes , Hvitved-Jacobsen Thorkild
Published: May 2018

A methodology for characterisation and a concept for modelling of aerobic microbial transformations of resuspended sewer sediments based on long term measurements of oxygen utilisation rates (OUR's) are presented. The OUR measurements were evaluated applying a conceptual model for aerobic microbial transformations of sewer solids based on methodologies originating from description of activated sludge processes. Validation showed that yield coefficient and maximum growth rate could be considered constant when readily biodegradable substrate was added to the resuspended sewer solids during the OUR experiment. Maintenance energy requirement of the biomass was argued to be a better concept for modelling microbial transformations compared with either considering decay of biomass into hydrolysible substrate or including endogenous decay of biomass. OUR measurements are recommended as a valuable methodology for characterisation of suspended sewer sediments in terms of COD-fractions and related biotransformations.
Biological denitrification of a textile effluent in a dynamic sand filter
Authors: Canziani R. , Bonomo L.
Published: May 2018

Post-denitrification of a pre-treated textile effluent was tested in a pilot-scale dynamic up-flow sand filter, which has been used as a biofilm reactor, together with filtration of suspended solids (SS) and decolorization. The potential application of the reactor as a three-in-one unit (decolorization, filtration and denitrification) has been successfully tested. Biomass growth and the sloughing of biological film did not prevent the removal of high concentrations of influent SS. Both pilot- and bench-scale tests confirmed that the intrinsic denitrification kinetics was zero-order, corresponding to a half-order removal rate if nitrate concentration is lower than 10 mgN l−1. Zero-order and half-order kinetic constants have also been calculated. At low nitrate loading rates (up to 2 kgN m−3 d−1) the filter followed the ideal plug-flow hydrodynamic model. In the lower part of the filter, zero-order kinetics fitted denitrification removal rates, while in the upper part of the filter denitrification followed half-order kinetics. At nitrate loading rates higher than 2.5 kgN m−3 d−1, nitrogen bubbles developed and partially mixed the reactor. Consequently, flatter concentration profiles were detected in the reactor and denitrification followed half-order kinetics along the entire filter.
Operational optimization of batchwise nutrient removal from wastewater by carrageenan immobilized Chlorella vulgaris
Authors: Lau P. S. , Tam N. F. Y. , Wong Y. S.
Published: May 2018

Cyclic batchwise operations using carrageenan immobilized Chlorella vulgaris beads were employed to remove nutrients (N and P) from primary settled wastewater. The NH4+-N removal efficiency at the end of each 3-day treatment cycle under Continuous-Contact mode operation dropped from 95.6% in the first cycle to 65.4% in the third cycle. If 3-day delay period was allowed at the end of each treatment cycle as in Contact-Delay mode operation, the NH4+-N removal efficiency was maintained at over 90% even at the end of the third cycle. With a rehardening process at the end of each treatment cycle as in the Contact-Rehardening mode operation, carrageenan algal beads maintained over 95% NH4+-N removal for all 4 cycles tested. Reduction of NH4+-N was through algal uptake and bead adsorption. Over 90% PO43−-P reduction was recorded in all cycles in all the three operation modes through algal uptake and some other unknown mechanisms. Though rehardening process could strengthen and delay the problem, massive leakage became unavoidable once the gel beads were saturated with cells as a result of growth and proliferation within the gel beads.
Dynamic modelling of enhanced biological phosphorus and nitrogen removal in activated sludge systems
Authors: Maurer M. , Gujer W.
Published: May 2018

A dynamic model for the description of enhanced biological phosphorus removal is presented. Model approach and structure were mainly adopted from the “Activated Sludge Model (ASM) No 2”. Two additional processes for the anoxic growth of phosphorus accumulating organisms (PAO) and anoxic storage of polyphosphate were included. The model was further enhanced with three processes describing biologically induced phosphorus precipitation. Stoichiometric coefficients for anoxic conditions are modified under the consideration of a 35% reduction of energy yield compared with oxygen as electron acceptor. In addition, a ratio for the anaerobic P-release per substrate taken-up is introduced, which depends on pH, glycogen and substrate. With the aid of 18 batch-experiments and measurements from a WWT pilot plant, a set of kinetic parameter was estimated, that was able to reproduce satisfactorily the nutrient removal behaviour of the investigated sludge.
First flush effects in an urban catchment area in Aalborg
Authors: Larsen Torben , Broch Kirsten , Andersen Margit Riis
Published: May 2018

The paper describes the results of measurements from a 2 year period on a 95 hectare urban catchment in Aalborg, Denmark. The results of the rain/discharge measurements include 160 storm events corresponding to an accumulated rain depth of totally 753 mm. The water quality measurements include 15 events with time series of concentration of SS, COD, BOD, total nitrogen and total phosphorus. The quality parameters showed significant first flush effects. The paper discusses whether either the event average concentration or the accumulated event mass is the most appropriate way to characterize the quality of the outflow.
Development of passive samplers for the detection of chlorinated hydrocarbons in sewers
Authors: Vorkamp Katrin , Haas Bettina S. , Herrmann Reimer
Published: May 2018

In this work a system of passive samplers was developed to examine volatile chlorinated hydrocarbons in the gas phase of sewer systems. The adsorption kinetics of chloroform, trichloroethylene and perchlor-ethylene on the adsorption materials Tenax TA, Amberlite XAD-2, Activated Charcoal, Carbosieve S-III and Carboxen-553 were surveyed in laboratory experiments. The highest values of recovery were found for Tenax TA. Further experiments were conducted, regarding the influence of different temperatures. The only significant deviation from the reference kinetics was observed at a temperature as low as 4°C. In order to examine sewer gases a stainless steel sampling system was designed which contained six glass cartridges filled with Tenax TA, and which could be fixed to th steps in the manholes. Using this system, samples were taken at seven locations within the sewer network of Bayreuth, a medium-sized town with little industry, in order to optimise the period of sampling. At least one of the three compounds could be detected at six locations within one week of sampling. An amount of perchloroethylene which exceeded all other results by two orders of magnitude indicated the large adsorption capacity of the chosen material Tenax TA. A linear decrease with increasing height above the waste water table was found; furthermore the sampling device was proved suitable for the localisation of sources of discharge.
Advanced real time control of a combined sewer system
Authors: Petruck Andreas , Cassar Andreas , Dettmar Joachim
Published: May 2018

The research project ‘Real Time Control of a Combined Sewer System by Radar estimates of Precipitation’ seeks to improve the water quality of a stream by reducing quantitative and qualitative discharges of combined sewage overflow (CSO). The complex monitoring and simulation system that has been set up for control purposes is described. Two advanced real time control (ARTC) strategies have been developed. First a pollution based real time control (PBRTC) strategy, and second a water quality based real time control (WQBRTC) strategy. The PBRTC strategy is already implemented, the WQBRTC strategy will be implemented during the course of the project. For the PBRTC an off-line analysis is presented to show the effectiveness of the strategy.
Tide-tank system simulating mangrove wetland for removal of nutrients and heavy metals from wastewater
Authors: Chu H. Y. , Chen N. C. , Yeung M. C. , Tam N. F. Y. , Wong Y. S.
Published: May 2018

Kandelia candel plants were grown in a simulated tide-tank system in the greenhouse to determine the performance of the mangrove ecosystem in treating synthetic wastewater of various strengths (NW, 5NW and 25NW). NW had a strength similar to the natural municipal wastewater, while 5NW and 25NW had 5 and 25 times, respectively, the amount of nutrients and heavy metals as in NW. The system was flooded daily with artificial seawater to simulate the tidal regime. Synthetic wastewater was irrigated to the system three times a week for 3 months. The results of effluent characteristics showed that the removal efficiencies of nutrients and metals from the wastewater were nearly 98% (except for organic N) and 96%, respectively, in NW and 5NW tanks whereas those of 25NW tanks were 75% for nutrients, 92% for Cd, Cr, Cu and around 88% for Ni and Zn. This study demonstrated that the mangrove ecosystem had a very high capacity to retain or immobilize the nutrients and heavy metals in the wastewater suggesting mangrove wetland had inherent physical, chemical and biological properties for adsorption and utilization of nutrients and heavy metals.
On the role of aluminium hydroxide in the conditioning of an alum sludge
Authors: Papavasilopoulos E. N. , Bache D. H.
Published: May 2018

This study dwells on the optimum dosage of a nonionic polymer during the conditioning of an alum sludge arising from the treatment of a coloured, upland water. Dewaterability was investigated through Capillary Suction Time (CST) and Specific Resistance to Filtration (SRF) tests, together with viscosity measurements on the liquid phase of sludge. The optimum dose associated with CST and SRF was 1.5 kg/T while for the case of viscosity behaviour it was 2.0 kg/T. From polymer adsorption studies on the sludge, it was shown that the optimum doses associated with the viscosity measurements were linked to a dose at which the adsorption capacity reached a saturation value (1.8 kg/T). The SRF and CST optima were found to correspond to a state of 70-85% of the saturation coverage. Parallel adsorption tests on alum sludge and pure precipitate showed that polymer adsorption on the precipitate was the prime determinant of the adsorption characteristics of the sludge and suggested that the optimum dose was linked to the mass of precipitate present in the sludge.
Nocardia effects in waste activated sludge
Authors: Pagilla Krishna R. , Jenkins David , Kido Wendell
Published: May 2018

Two effects of Nocardia in waste activated sludge (WAS) were investigated: (i) the influence of WAS in the solids treatment recycle streams on Nocardia persistence in the activated sludge, and (ii) the effect of Nocardia in WAS on anaerobic digester foaming. About 4% of the Nocardia present in the mixed liquor was due to seeding from the WAS solids in the dissolved air flotation thickener recycle stream recycle. Nocardia filaments in WAS at levels of between 104 to 106 intersections/g VSS resulted in Nocardia levels of approximately 104 to 105 intersections/g VSS in anaerobic digesters that treated both WAS and primary sludge. The effect of disinfecting these Nocardia filaments in the WAS with Cl2 was investigated at Cl2 dose ranges of 20-60 mg Cl2/l WAS and 100-200 mg Cl2/l WAS on a lab scale using batch foaming tests to assess success. Chlorination with 20 - 60 mg Cl2/l WAS approximately doubled both sludge foaming potential and foam stability. At Cl2 doses of 100-200 mg Cl2/l WAS, foaming potential was increased almost 10-fold, and foam stability was increased by 2.5 times. These results indicate that chlorination of WAS feed to an anaerobic digester for inactivation of Nocardia should not be practiced.
Understanding and management of cyanobacterial blooms in sub-tropical reservoirs of Queensland, Australia
Authors: Jones Gary J. , Poplawski Wojciech
Published: May 2018

A three year study of two sub-tropical water supply (potable and irrigation) reservoirs - Baroon Pocket and Leslie - aimed to develop an improved understanding and effective management strategy for the control of low level toxic cyanobacterial ‘blooms’. The two reservoirs appear to be typical of those elsewhere in tropical and sub-tropical Australia, being strongly stratified and monomictic if deep, or polymictic to monomictic (depending on inter-annual climatic variation) if shallow. In both reservoirs, thermal stratification appeared to be the key factor influencing the onset and demise of cyanobacterial blooms. Hypolimnetic deoxygenation was rapid during periods of stratification, and high rates of nitrogen and phosphorus release from bottom sediments occurred during anoxia. External nutrient inputs were dominated by episodic storm in-flows following the passing of (sub)tropical depressions, carrying massive sediment and nutrient loads into the reservoirs. As a consequence of this, and coupled with the high degree of internal nutrient recycling and the low national targets for cyanobacterial control in Australia, we believe that reduction of external nutrient inputs alone, through improved catchment management, may not be sufficient to prevent cyanobacterial blooms. Therefore, more emphasis should be given to ‘in-lake’ control strategies such as destratification, biomanipulation and in situ sediment treatment.
Hydrolysis of (ligno)cellulosic materials under sulfidogenic and methanogenic conditions
Authors: Pareek S. , Kim S. K. , Matsui S. , Shimizu Y.
Published: May 2018

A Biochemical methane potential (BMP) test and Serum Bottle Reactor (SBR) test were used to compare hydrolysis (mineralization) of lignocellulosic materials under sulfidogenic and methanogenic conditions. Lignocellulosic carbon mineralization under sulfidogenic conditions was found to be more than 2 times higher than under methanogenic conditions. The percentages of lignocellulosic carbon mineralized under methanogenic condition were 18.0% and 10.71% while under sulfidogenic conditions 36.69% and 27.44% for office paper and newspaper, respectively. Although a poor linear relationship between the percentage of carbon mineralization and percentage lignin content was observed, but in general a decrease in mineralization of lignocellulosic carbon was observed with the increase in lignin content. A method based on selective inhibition of microorganism activity, by 3% toluene, was used to measure the initial rate of lignocellulosic material mineralization and the accumulation of mineralized products (i. e. sugars). Sugars linearly accumulated over time and the accumulation rates of glucose and xylose were calculated. The accumulation rates of glucose under methanogenic condition were 1.302, μM/g-dry wt hr and 0.004, μM/g-dry wt hr while under sulfidogenic condition they were 2.624, μM/g-dry wt hr and 2.279 μM/g-dry wt hr for offce and newspaper, respectively.
The characteristics of coagulation of fenton reaction in the removal of landfill leachate organics
Authors: Yoon J. , Cho S. , Cho Y. , Kim S.
Published: May 2018

The need to improve the Fenton process, which is one of the leachate treatment trains at Metropolitan Landfill in Korea was raised. This study was intended to compare the Fenton reaction with coagulation in removing landfill leachate organics of specific size. The organics fractionated by ultrafiltration and measured by TOC, were selected for evaluating the characteristics of the removal of organics. From this study it was found that the organic removal pattern in the Fenton reaction was quite similar to coagulation. Both reactions removed large leachate organics more readily and selectively. For example, coagulation removed 59~73% of organics larger than molecular weight (MW) of 500 and only up to 18% of organics less than MW of 500. On the other hand, the Fenton process removed 72-89% of organics larger than MW of 500 and only up to 43% of organics less than MW of 500. It was interpreted that the coagulation step in the Fenton process had a primary role in selective removal of leachate organics, though the Fenton reaction is not coagulation. However, since the efficiency of organic removal in the Fenton reaction was higher than coagulation, the Fenton process in Metropolitan Landfill leachate treatment process may be called “a type of enhanced coagulation”.
Storage reservoirs – a first barrier for pathogenic micro-organisms in the Netherlands
Authors: van Breemen Lambert W. C. A. , Ketelaars Henk A. M. , Hoogenboezem Wim , Medema Gertjan
Published: May 2018

Production of drinking water from river water, abstracted either directly from river or from storage reservoirs, requires the application of barriers for pathogenic micro-organisms. About one third of the total production of drinking water in the Netherlands is derived from surface water, mainly the River Meuse and branches of the River Rhine. The results of extensive monitoring programmes show that the microbiological water quality of the River Rhine and River Meuse is strongly influenced by domestic and agricultural waste water discharges, with respect to the River Meuse mainly in the Liège-region in Belgium. Densities of Cryptosporidium and Giardia in both rivers are comparable; the highest density was found in the Belgian Meuse basin. Elimination rates of 1.7- to 3.1 10log-units for pathogenic micro-organisms were found in Dutch storage reservoirs, which can thus be considered as an important first barrier for pathogenic microorganisms. The elimination capacity of reservoirs is influenced by retention time and contamination by waterfowl. To meet the proposed quality criteria for pathogens in drinking water, however, additional barriers are required.
Influence of raw water storage on Giardia, Cryptosporidium and Nematodes
Authors: Bertolucci G. C. , Gilli G. , Carraro E. , Giacosa D. , Puppo M.
Published: May 2018

A watershed derived from a disused gravel-quarry has been studied for the relocation of the catchment area of Turin surface water treatment plants. The improvement of river water quality as a consequence of short-term storage has been investigated, focusing the attention on three problem organisms, namely the parasitic protozoans Giardia spp. and Cryptosporidium spp. and the free-living Nematodes, which could be considered indicators of healthy compliance and product agreeability respectively.
Bubble dynamics and oxygen transfer in a speece cone
Authors: McGinnis Daniel F. , Little John C.
Published: May 2018

A model is developed that predicts bubble dynamics and oxygen transfer in a Speece Cone. The model is based on differential mass balances for both gas and water and requires a knowledge of cone dimensions, water flow rate, depth to the cone, and initial bubble diameter produced by the oxygen diffuser. The model calculates the oxygen transfer, nitrogen stripping, and gas-phase holdup within the cone. Experimental data for a Speece Cone have not been published; however, a modified version of the model is tested using data obtained from a hydrodynamically similar full-lift hypolimnetic aerator with good results. This process model, when coupled with a suitable cost model, should prove useful in the preliminary design and economic optimization of Speece Cone oxygenators.
UV disinfection of wastewater coagulated with ferric chloride: recalcitrance and fouling problems
Authors: Gehr R. , Wright H.
Published: May 2018

Collimated beam and pilot tests using low pressure or medium pressure UV lamps were conducted to assess the disinfection performance of a municipal wastewater which had been pretreated by ferric chloride coagulation followed by sedimentation. The feed to the UV systems contained high levels of Fe (often above 3 mg/l); suspended solids and UV254 transmission values were also not ideal (mean approximately 30 mg/l and 32% respectively). The collimated beam tests indicated that the target level of 2,500 coliform forming units/100 ml often could not be reached, and the pilot tests revealed significant fouling after only a few hours. Thus physicochemical effluents of this nature likely require upstream filtration (or a relaxation of the target level) and a continual, automated cleaning system to ensure that performance levels can be maintained.
An online simulation to support the operation of municipal sewage plants
Authors: Kolisch G. , Londong J.
Published: May 2018

It was investigated whether it is possible to calculate the operational behaviour of municipal sewage treatment plants online via coupling of the dynamic simulation with the process system. Standard software was used and the activated sludge process was described by the Activated Sludge Model No. 1. A method was developed, by which the 13 substance groups of the IAWQ model are calculated on a few online values with the use of multivariate regressions. Using the average values from 15 min. cycles, a continuously updated inflow file for the simulation of a sewage plant is created. To simulate the effluent behavior of a sewage plant online, a program surface was created. As an additional function, a prediction simulation can be performed, based on the current online-state. The work performed to date shows that practical problems at the site have the same significance as the establishment and calibration of the model.
A model of ditch vegetation in relation to eutrophication
Authors: Janse Jan H.
Published: May 2018

A functional model of a ditch ecosystem has been developed, aimed at describing the relation between nutrient input and water quality and dominant vegetation in drainage ditches. Its aim is the derivation of the ‘critical nutrient loading’ for a shift from submerged vegetation to duckweed dominance. The model, called PCDitch, describes the competition between several functional groups of macrophytes, as well as algae. The macrophyte groups were defined according to the layer(s) in which they grow: submerged, floating or emergent, rooted or non-rooted. The model also includes the cycling of nutrients within the water, the sediment top layer and the vegetation. The model has been applied to the data of 8 experimental ditches located at Renkum (The Netherlands), which received different levels of nutrient loading during 4 years. The controls and the low- and medium-loaded ditches remained dominated by submerged plants, while in the high-loaded ones a dense cover of duckweed developed. In the sand ditches, submerged biomasses were lower than in the respective clay ditches. An optimization study has been performed for a number of sensitive parameters, minimizing the total sum of squared differences between simulated and measured values for all ditches, resulting in a set of parameter values that gives the best overall fit. The parameters included the maximum growth rates, the minimum phosphorus contents and the overwintering fraction of the plant groups. The model simulations by PCDitch were grossly comparable to the field observations, with duckweed in the high-loaded ditches and submerged plants in the other ones. The fit for algae and charophytes remained poor. Further calibration as well as testing the model in field situations are recommended to improve the model's predictive value.
Stable states, buffers and switches: an ecosystem approach to the restoration and management of shallow lakes in the Netherlands
Authors: Hosper S. Harry
Published: May 2018

Lake restoration in the Netherlands has been focused mainly on the control of external P loading from point sources. However, this approach did not result in the water quality desired. The algae-dominated turbid water state may be extremely stable, and then additional measures are necessary to remove certain ‘blockages’ such as: the persistent bloom of Oscillatoria algae, the P release from the lake sediments, and the abundance of fish, preventing zooplankton and submerged macrophytes from developing. This paper addresses: (1) the need for an ecosystem approach, (2) the resistance of shallow lake ecosystems to changes in nutrient loading, (3) the concept of stable states, buffers and switches, and (4) the perspectives for lake restoration in the Netherlands. Priority should be given to fighting the Oscillatoria blooms. Winter flushing with water low in TP and algae proved to be an effective tool for reducing these blooms. Reduction of planktivorous fish, such as bream and roach, could enhance the top-down control of algae through the grazing by zooplankton, particularly by the large Daphnia species.
Comprehensive approaches to eutrophication management: the Australian example
Authors: Banens R. J. , Davis J. R.
Published: May 2018

Eutrophication is one of the major environmental issues facing Australia. Responses to this issue include short-term management strategies principally focusing on operational activities, and long-term strategies focusing on nutrient reduction, flow management, education, monitoring and research. Because nutrients were found to be largely derived from rural areas, community education and involvement of land holders formed a central element of the longer-term strategies. The voluntary and co-operative approach adopted was considered to be more effective than a regulatory or coercive approach in improving diffuse phosphorus source management. Research was particularly necessary because of a relatively poor Australian knowledge base, and the need to rely on overseas understandings and management experiences. Australia has a number of environmental characteristics - episodic rainfall and runoff, higher year-round temperatures, old shallow soils and higher river turbidity - to suggest that research into the causes and management of eutrophication under Australian conditions is necessary. Historical reports suggest that some of these factors may make Australian waters naturally susceptible to eutrophication. The National Eutrophication Management Program was established to fund, co-ordinate and communicate research activities. Preliminary research findings suggest that the accepted northern hemisphere eutrophication paradigm does not always fit.
Respirometry based optimal control of an aerobic bioreactor for the industrial waste water treatment
Authors: Moreno Jaime , Buitrón Germán
Published: May 2018

A methodology and mathematical simulation for the time optimal control of an activated sludge sequencing batch reactor (SBR) for toxic waste water degradation is presented. An optimal strategy for the input flow was obtained using techniques of optimal control theory, such that the reaction time is as small as possible. The degradation time was controlled through the substrate concentration estimated from the liquid oxygen concentration, which is much simpler to measure. The simulation of a toxic effluent containing phenol showed that the degradation time, obtained with the optimal strategy, was a half of that obtained when the reactor is stopped at the end of the reaction period, but filled without the optimal strategy.