bluuebunny/crossref_metadata_2025 huggingface dataset:
Energy saving in the aeration process by fuzzy logic control
Authors: Ferrer J. , Rodrigo M. A. , Seco A. , Penya-roja J. M.
Published: May 2018

An aeration fuzzy logic based control system has been developed and tested in the main aerobic reactor of a BARDENPHO process pilot plant. This system has been compared with two ordinary aeration process controllers: one- and two-aeration-level on/off controllers. Energy savings of about 40% over the one-level on/off controller and a more stable closed-loop response have been obtained. Thus, an improvement of about 60% in average deviation can be accomplished by the use of an AFLBC.
Bioavailability of phosphorus as a tool for efficient P reduction schemes
Authors: Gerdes Peter , Kunst Sabine
Published: May 2018

The bioavailability of phosphorus from different sources has been evaluated in the catchment area of the River Ilmenau (Lower-Saxony, Germany) by using algal assays. The P bioavailability describes the different potential of P from various sources of supporting eutrophication. Effluents from sewage treatment plants were highly bioavailable (72% of TP) whereas rainwater (26%) and erosion effluents (30%) showed a low bioavailability. In order to develop effective strategies to minimize P inputs into the river, source specific P bioavailability indices were determined and combined with a P balance to calculate inputs of vioavailable P (BAP) instead of total P (TP). It could be shown that the relative importance of the different P sources changes when applying BAP. Measures to reduce P inputs into the River Ilmenau will take P bioavailability into consideration and therefore lead to a more cost-effective management.
Development of a new system for control and optimization of small wastewater treatment plants using oxidation-reduction potential (ORP)
Authors: Zipper T. , Fleischmann N. , Haberl R.
Published: May 2018

For the development of new control strategies for small activated sludge systems (<500 P.E.) the oxidation-reduction potential (ORP) has been tested as a suitable parameter. Batch and continuous experiments in a pilot plant with alternating nitrification and denitrification phases proved the relation between the actual load and the behaviour of ORP in the aeration tank. Using a two-point controller, increasing load correlated with an extension of aerated phases in relation to unaerated phases. Decreasing load equalled to a decrease of the ratio of nitrification time-cycle time. On the basis of these results an ORP controller has been developed allowing both automatic setup and on-line adaption. Operational results from a pilot plant are presented, including effluent quality and energy efficiency.
Frameworks for assessing reliability of multiple, independent barriers in potable water reuse
Authors: Haas Charles N. , Trussell R. Rhodes
Published: May 2018

The development of potable water reuse systems (systems for the treatment of wastewater to quality adequate to augment other surface water supplies) requires careful attention to the consistent production of product water which has low levels of contaminants, such as infectious pathogens, capable of causing human health effects from acute exposure. Little consideration has been given to the formal specification of the degree of reliability of such systems. In this paper we present two ways to approach the problem. The first is a formal extension of the ‘multiple barrier’ concept often cited in the water treatment literature. The second is an application of probabilistic analysis. With either method, it is clear that much more information should be obtained with respect to the failure modes, and the frequency with which individual processes achieve a particular level of performance. However the conceptual framework presented here should enable a formal analysis of the problem to be conducted.
Effluent pretreatment by iron coagulation applying various dose-pH combinations for optimum particle separation
Authors: Adin A. , Soffer Y. , Aim R. Ben
Published: May 2018

Wastewater reuse often requires particle destabilization and removal to protect water transport systems and membranes from clogging. Flocculation process of activated sludge effluent applying ferric chloride is examined and comparison with alum (aluminium sulfate) application is made in this work. Optimum flocculation conditions are determined based on the removal efficiency of different particle size groups and on turbidity as a function of coagulant dosage and pH. Results show that the best removal for ferric chloride coagulant occurs at pH 4-5 and dosage of 20-30 mgl−1. Settled water total particle count (TPC) of particle size ≥2μm was reduced by more than 99%, while turbidity removal reached 86%. Zeta potential measurements and visual observations indicate domination of adsorption and charge neutralization mechanisms. Best removal with alum occurred at pH 6-7 while dosing 30 mgl−1 and higher. Destabilization mechanism of adsorption and sweep coagulation is proposed. Generally alum performed somewhat better than iron for turbidity removal and worse for TPC removal. CMD (count mean diameter) is proposed for particle removal index: the higher the TPC removal, the lower the CMD.
Media properties and their effect on filter performance and backwashing
Authors: Fitzpatrick C. S. B.
Published: May 2018

Granular filter media used in water treatment have a range of physical properties. Media are usually selected on the basis of size, but bed behaviour is also affected by density and voidage of the media, particularly during backwashing. The fluidisation and backwashing bed behaviour of a number of filter media have been investigated. It has been found the fluidisation is affected by the bed packing arrangement which is determined by previous treatment. Filter media may be subject to attrition during backwashing which will affect the grain size and voidage. Combined air and water flow rates for collapse-pulsing are also affected by the media characteristics. When collapse-pulsing is used to clean triple media filters, complete mixing of the layers occurs, but restratification is possible using a high rate fluidising water wash. Backwashing is an important part of the filtration process so understanding the effect of media properties on the process is essential for optimisation.
Enhancement of hydroxyl radical generation by phenols and their reaction intermediates during ozonation
Authors: Utsumi Hideo , Han Sang-Kuk , Ichikawa Kazuhiro
Published: May 2018

Generation of hydroxyl radicals, one of the major active species in ozonation of water was directly observed with a spin-trapping/electron spin resonance (ESR) technique using 5,5-dimethyl-1-pyrrolineN-oxide (DMPO) as a spin-trapping reagent. Hydroxyl radical were trapped with DMPO as a stable radical, DMPO-OH. Eighty μM of ozone produced 1.08 X 10-6M of DMPO-OH, indicating that 1.4% of •OH is trapped with DMPO. Generation rate of DMPO-OH was determined by ESR/stopped-flow measurement. Phenol derivatives increased the amount and generation rate of DMPO-OH, indicating that phenol derivatives enhance •OH generation during ozonation of water.

Ozonation of 2,3-, 2,5-, 2,6-dichlorophenol gave an ESR spectra of triplet lines whose peak height ratio were 1:2:1. ESR parameters of the triplet lines agreed with those of the corresponding dichloro-psemiquinone radical. Ozonation of 2,4,5- and 2,4,6-trichlorophenol gave the same spectra as those of 2,5- and 2,6-dichlorophenol, respectively, indicating that a chlorine group in p-position is substituted with a hydroxy group during ozonation. Amounts of the radical increased in an ozone-concentration dependent manner and were inhibited by addition of hydroxyl radical scavengers. These results suggest that p-semiquinone radicals are generated from the chlorophenols by hydroxyl radicals during ozonation. The p-semiquinone radicals were at least partly responsible for enhancements of DMPO-OH generation.
Improvement of the surface water quality in the Berlin region
Authors: Heinzmann Bernd
Published: May 2018

The waterbodies of the Berlin region are intensively used for different purposes. High importance is given to the water supply to gain drinking water from groundwater and bank filtrate and for the recharge of groundwater. For these applications a good surface water quality would be an advantage, but the water bodies are loaded with treated sewage, stormwater and combined sewer overflow. This leads to quality problems in the water bodies, especially eutrophication, requiring scientifically based water quality targets for phosphorus. Measures for the reduction of eutrophication in rivers and lakes are presented in this paper, illustrating two different situations, that have been achieved through Berlin's efforts at reducing phosphorus loading.
Statistical approach for describing failures and lifetimes of water mains
Authors: Lei Jianhua , Sægrov Sveinung
Published: May 2018

This paper demonstrates the statistical approach for describing failures and lifetimes of water mains. The statistical approach is based on pipe inventory data and the maintenance data registered in the data base. The approach consists of data pre-processing and statistical analysis. Two classes of statistical models are applied, namely counting process models and lifetime models. With lifetime models, one can estimate the probability which a pipe will fail within a time horizon. With counting process models one can see the deteriorating (or improving) trend in time of a group of “identical” pipes and their rates of occurrence of failure (ROCOF). The case study with the data base from Trondheim municipality (Norway) demonstrates the applicability of the statistical approach and leads to the following results: 1). In the past 20 years, Trondheim municipality has experienced approximately 250 to 300 failures per year. However, the number of failures per year will significantly increase in the near future unless better maintenance practice is implemented now. 2). Unprotected ductile iron pipes have a higher probability of failures than other materials. The average lifetime of unprotected ductile iron pipes is approximately 30 to 40 years shorter than the lifetime of a cast iron pipe. 3). Pipes installed 1963 and 1975 are most likely to fail in the future; 4) The age of a pipe does not play a significant role for the remaining lifetime of the pipe; 5). After 2 to 3 failures, a pipe enters a fast-failure stage (i.e., frequent multiple between failures).
Effect of pre-sonication on removal of organic matters resulting from chlorinated humic acids
Authors: Ma Ying-Shih , Lin Jih-Gaw
Published: May 2018

Humic acids are amorphous organic macromolecules that are responsible for the color of natural water. They play an important role in the formation of disinfection by-products, the stabilization of wastewater sludge, and the treatment of wastewater. An ultrasonic process is applied as a pretreatment method for the purpose of reducing the risk of chlorinated by-products. Experimental results indicate that the initial pH, ionic strength, and chlorine demand affect the amount of total organic carbon removal and Cl2 consumption significantly. The formation of chlorinated by-products depends on both the initial pH and ionic strength. Experimental results also propose a good agreement that the humic acid can be removed efficiently by ultrasonic pretreatment under aerobic conditions. In this study, when the ultrasound/O2 process is used as a pretreatment method, the biodegradability which is defined as the formation of BOD5 increases with sonication time.
Henry's constants and mass transfer coefficients of halogenated organic pollutants in an air stripping packed column
Authors: Chiang Pen-C. , Hung Chung-H. , Mar J. C. , Chang E. E.
Published: May 2018

Both Henry's constants and volumetric mass transfer coefficients (KLa) of eight priority chlorinated organic compounds including 1,1-dichloroethene, methylene chloride, chloroform, carbon tetrachloride, 1,1,1-trichloroethane, trichloroethylene, tetrachloroethylene, and 1,4-dichlorobenzene in an air stripping packed column were investigated in this study. The liquid and gas phase EPICS (Equilibrium Partition in Closed System) and direct calculating methods were applied to determine the Henry's constants of VOCs. The interference of co-solute on Henry's constants was also investigated. Experimental results indicated that decrease in Henry's constants of VOCs was observed in the presence of humic acid but no apparent effect on Henry's constants was detected when there was NaCl and surfactant in solution. Four different configurations of packing media including Intalox Saddle, Super Intalox Saddle, Telleret, and Hedgehog made of polypropylene were respectively packed in the air stripping tower and investigated in the study. The dependence of hydraulic loading, air-water ratio, and configurations of packing media on mass transfer coefficients of VOCs was discussed.
A simplified method for assessing the saturation efficiency at full-scale dissolved air flotation plants
Authors: Steinbach S. , Haarhoff J.
Published: May 2018

This paper proposes a simplified yet comprehensive method for measuring the efficiency of air saturation systems used in dissolved air flotation. It is based on a review of methods suggested by other researchers in this field, but several improvements to existing methods are made. A saturation air composition different than that of atmospheric air and incomplete precipitation in the measuring unit after pressure release are taken into consideration. The developed measurement and calculation procedure provide engineers and operators alike with an easy tool to assess the saturation efficiency of their system at full-scale DAF plants as well as at pilot and laboratory scale plants.
The comparison of trichloroethylene removal rates by methane- and aromatic-utilizing microorganisms
Authors: Lu C.-J. , Lee C. M. , Chung M.-S.
Published: May 2018

The comparison of TCE cometabolic removal by methane, toluene, and phenol utilizers was conducted with a series of batch reactors. Methane, toluene, or phenol enriched microorganisms were used as cell source. The initial cell concentration was about 107 cfu/mL. Methane, toluene, and phenol could be readily biodegraded resulting in the cometabolic removal of TCE. Among the three primary carbon sources studied, the presence of phenol provided the best cometabolic removal of TCE. When the concentration of carbon source was 3 mg-C/L, the initial TCE removal rates initiated by methane, toluene, and phenol utilizers were 1.5, 30, and 100 μg/L-hr, respectively. During the incubation period of 80 hours, TCE removal efficiencies were 26% and 96% with the presence of methane and toluene, respectively. However, it was 100% within 20 hours with the presence of phenol. For phenol utilizers, the initial TCE removal rates were about the same, when the phenol concentrations were 1.35, 2.7, and 4.5 mg/L. However, TCE removal was not proportional to the concentrations of phenol. TCE removal was hindered when the phenol concentration was higher than 4.5 mg/L because of the rapid depletion of dissolved oxygen. The presence of toluene also initiated cometabolic removal of TCE. The presence of toluene at 3 and 5 mg/L resulted in similar TCE removal. The initial TCE removal rate was about 95 μg/L-hr at toluene concentrations of 3 and 5 mg/L compared to 20 μg/L-hr at toluene concentration of 1 mg/L.
Biodegradation of UV-irradiated polychlorinated biphenyls in surfactant micelles
Authors: Shi Zhou , LaTorre Keith A. , Ghosh Mriganka M. , Layton Alice C. , Luna Scott H. , Bowles Leslie , Sayler Gary S.
Published: May 2018

Potential enhancement of biodegradability of commercial polychlorinated biphenyls (PCBs) mediated by photodechlorination was investigated. Used in tandem, photolysis and biodegradation of Aroclor 1242 (MW≈260), a commercial PCB mixture, dissolved in micellar solution of a nonionic surfactant, polyoxyethylene 10 lauryl ether (POL(10)), was studied. A mixed population of two genetically engineered microorganisms (GEMs), Pseudomonas putida IPL5∷TnPCB and Ralstonia eutropha B30P4∷TnPCB, was used for the aerobic biodegradation of POL (10) while cometabolizing Aroclor 1242. UV-irradiation at 254 nm for 40 minutes caused 63% degradation of Aroclor 1242 in a solution containing 210 mg/L of PCB congeners in 4 g/L POL(10). In the same period, 42% of the PCB chlorine appeared as chloride in solution. Gas chromatograms of UV-irradiated Aroclor 1242 solutions indicated that almost all biorecalcitrant PCB congeners, especially the highly chlorinated ones, were photolyzed. PCB GEMs removed an additional 30 mg/L (14.3%) of the PCBs in 96 hr from the UV-irradiated micellar PCB solution. Seemingly, the products of photolysis did not inhibit biodegradation of the remaining congeners or the surfactant.
The effects of pH and addition of an organic buffer (HEPES) on nitrate transformation in Fe0-water systems
Authors: Zawaideh Lara L. , Zhang Tian C.
Published: May 2018

The feasibility of using zero-valent iron (Fe0) powder to remediate nitrate-contaminated water was studied using bench-scale batch reactors. Operational parameters, such as Fe0 dosage (w/v), initial concentration of nitrate-nitrogen, pH, and the use of an organic buffer (HEPES) were studied, specifically focusing on the effects of pH and the addition of HEPES on nitrate transformation using zero-valent iron powder. Nitrate-nitrogen was removed by 94% when 0.01M of HEPES was added to a non-shaking batch reactor containing 20 mg/l nitrate-nitrogen and 4% (w/v) of Fe0. Shaking was proved to be more efficient than no shaking. Using the response surface methodology it was found that nitrate removal was closely related to pH. At low pH (e.g., pH < 2), the nitrate removal was fast and efficient (95% to 100%). At high pH (e.g., pH > 11), the transformation of nitrate was fast and efficient only for low concentration of nitrate in the Fe0-H2O system. At normal pH range (pH = 6 to 8), nitrate removal was usually lower than 50% without buffer treatment. The addition of the organic buffer (HEPES) could greatly enhance the nitrate transformation in a wide pH range (e.g., pH = 2 to 11).
Humic substances affecting the limitation of the activated sludge process for removal of micropollutants
Authors: Matsui Saburo , Yamamoto Hiroshi , Shimizu Yoshihisa , Harada Jun , Einaga Daisuke
Published: May 2018

In our previous investigation with the Bacillus subtilis rec-assay, a strong DNA-damaging potential was found in effluents of municipal wastewater treatment plants and nightsoil treatment plants using the activated sludge process. We hypothesized that the presence of non-biodegradable humic substances in the influent and the association of micropollutants inducing DNA-damaging chemicals to them may cause the comparatively lower removal rate of micropollutants than that of primary organic substrates. In this research, a batch type activated sludge process was set up in the laboratory to examine the fate of these toxic micropollutants and to evaluate the effect of humic substances. As neutral and polar micropollutants, pyrene and 1-aminopyrene was respectively selected, and their speciation (i.e., free, sorbed onto dissolved organic matters including humic acid, and sorbed onto activated sludge) was investigated. Almost all pyrene was sorbed onto activated sludge without any biodegradation. It was observed that the effect of humic substances made both pyrene and 1-aminopyrene leave the process in forms sorbed onto humic acid and free in the effluent. This complexity of the fate of micropollutants and the significant effect of humic acid leads to the necessity of further investigation not only in the activated sludge process but also into the other various natural environments.
Hsp104 expression and morphological changes associated with disinfectants in saccharomyces cerevisiae: environmental bioassay using stress response
Authors: Fujita K. , Iwahashi H. , Kawai R. , Komatsu Y.
Published: May 2018

On exposure of Saccharomyces cerevisiae to sublethal concentrations of disinfectants such as TPN, Thiuram, Captan and Oxine-copper; 70-, 90-kDa proteins and heat-shock protein Hsp104 were induced without morphological changes. Considering these stress proteins as critical signs, we can determine how cells are damaged by pesticides under sublethal conditions. Furthermore, Hsp104-lacZ hybrid gene (a lacZ gene put under control of Hsp104 promoter) in S. cerevisiae was sensitively expressed in the presence of sublethal concentrations of these disinfectants by measuring the relative β-galactosidase activity. It follows that not only monitoring the growth phase or the induction of synthesized proteins but also detecting the level of gene expression shows the chemical stress response rapidly, conveniently and reproducibly. We conclude that the use of a yeast strain with a stress reporter gene is a novel and simple bioassay relative to human health and to the ecosystem in general.
Pesticides - friend or foe?
Authors: Richardson Mervyn
Published: May 2018

Pesticides, where used correctly, can save up to 40% in crop losses; however, when pesticides are mal-, mis-or over-used the environmental and public health consequences can be very considerable. The United Nations has issued a list of chemicals that are banned or severely restricted in use; many of the chemicals on this list are pesticides. Whilst the use of highly persistent pesticides such as DDT has proved very effective in the eradication of diseases such as malaria, the adverse effects to the natural environment have been devastating - whole populations of birds have been eliminated.

Within the former Soviet Union, the use of highly persistent pesticides was widespread; this has resulted in contamination of both crops, with pesticide residues well in excess of internationally acceptable maximum residue limits, and water resources to such high level that remediation through natural processes will take decades, or by xenobiotic or physicochemical processes will be extremely costly. This is an extraordinary situation as the former Soviet Union had one of the most stringent of environmental regulation - the GOST regulations; unfortunately these were not pragmatic and rarely applied. When in the Ukraine in 1994, I heard that farmers where paid for every application made; the result was crops, soil, water and the environment were highly contaminated, and in some cases the land became barren. Currently, the situation in some countries is that no pesticides are being applied because under the new market conditions farmers cannot afford to purchase pesticides. In Armenia in July 1995, one could not purchase fruit which was not diseased.

The effects of mis-use of pesticides are known to cause very serious adverse effects to human health: in some countries children are exhibiting excessive cancer incidences; crops found to be highly contaminated with up to five different pesticides are being condemned, often being burnt in the fields. As these crops in all probability contained now banned and highly persistent pesticides, mere burning at low temperatures is producing even more toxic dioxins, furans, etc. This leads to both air and soil contamination. One answer would be for the farmer to be obliged to pay for high-temperature incineration in a high-tech incinerator in a developed country, which, subject to prior informed consent, could cost US $5000/tonne.

However, the application of modern pesticides in accordance with manufacturers' specifications can incur none of these problems; this presentation will outline how pesticides can be used judiciously.
Assessment of groundwater contamination in the vicinity of a municipal solid waste landfill (Zagreb, Croatia)
Authors: Mikac Nevenka , Cosovic Božena , Ahel Marijan , Andreis Svjetlana , Toncic Zdenka
Published: May 2018

The environmental impact of the main landfill of the city of Zagreb (Croatia), which contains about 5 million tons of waste, on the adjacent groundwater was studied. The waste is disposed of directly onto the highly permeable alluvial sediments, only few kilometres upstream of a large protected groundwater zone. Systematic monitoring was performed in the framework of a major project aimed to assess strategies for remediation of the landfill. Results obtained in 6 sampling campaigns during 1995-96 were used to determine the redox zones in the leachate plume and to describe horizontal and vertical distributions of selected contaminants. A relatively narrow non-continuous iron-reducing zone was found along the edge of the landfill in the prevailing directions of the groundwater flow. Even after a distance of 1200 m the redox conditions in the aquifer still remained anaerobic (nitrate-reducing), while a permanently aerobic zone was present only upstream from the landfill. The horizontal distribution of the contaminants was highly dependant on the hydrological regime, but the preferential direction of spreading was toward the protected groundwater zone. Moreover, it was shown that this aquifer section is polluted not only in the surface layer but across its whole vertical profile (as deep as 60 m).
Impact of organic ligands on uranium removal during anaerobic biological treatment
Authors: Robinson Kevin G. , Ganesh Rajagopalan , Reed Gregory D.
Published: May 2018

Anaerobic batch experiments were conducted to evaluate the reduction and precipitation of U6+ complexed to acetate, oxalate, citrate and tiron using a pure culture of sulfate reducing bacteria (Desulfovibrio desulfuricans). These ligands were chosen to evaluate the nature of complex formation on uranium bioreduction. Experiments in which uranium was initially complexed to the ligand (>92%) indicated that bacteria reduce U6+ to U4+ in the presence of each ligand tested. The rate of acetate complexed uranium reduction was fastest and that of citrate complexed uranium was slowest. Precipitation of reduced uranium was evaluated by filtering the reduced complex through 0.2 μm filters. The U4+ formed after biotransformation in acetate solutions was retained on the filter whereas U4+ in the oxalate, citrate and tiron solutions passed through the filter. When ligand concentrations were lowered (44–50% of the uranium initially complexed) a greater amount of UO2 precipitate from oxalate samples was collected on the filter indicating that ligand concentration can impact uranium removal via precipitation. Little or no precipitate was collected from citrate or tiron containing solutions. The preferred reaction of U4+ appeared to be recomplexation with these ligands rather then precipitation as UO2.
The impact of contamination from a municipal solid waste landfill (Zagreb, Croatia) on underlying soil
Authors: Ahel Marijan , Mikac Nevenka , Cosovic Bozena , Prohic Esad , Soukup Vesna
Published: May 2018

The present study was conducted on the main landfill of the city of Zagreb which contains about 5 million tons of waste disposed of directly onto highly permeable alluvial sediments. The investigations were aimed at assessing the impact of contamination from the landfill on underlying soil and comprised the determination of a broad spectrum of inorganic and organic constituents in the samples (size fractions <2 mm) of solid waste, soil and aquifer sediments. Both the total content of various contaminants as well as their part which is readily leachable with water were determined in the examined samples. Compound classes identified in the landfill can be classified into the two main categories: (1) markers of biological waste and of its microbial transformation (ammonia, dissolved organic carbon, short-chain aliphatic acids, phenols, derivatives of abietic acid) and (2) markers of anthropogenic waste (toxic metals, hydrocarbons, chlorinated hydrocarbons, surfactant-derived compounds, phthalates, pharmaceutical chemicals). The complex assemblages of contaminants were shown to change dramatically during the transport from the solid waste through unsaturated zone of the soil to aquifer sediments. It was shown that, in addition to the vertical infiltration of leachate from the solid waste, the hydrological regime of groundwater has also a strong impact on the contaminant distribution in soils below the landfill.
Influence of a uranium mine on the macrozoobenthic communities of the streams in the nearest environs, Slovenia
Authors: Trontelj Alenka , Ponikvar-Zorko Pavla
Published: May 2018

The aim of this non-radiological research was to determine the influence of uranium mine Žirovski vrh (Slovenia) with two dumps of tailings on the macrozoobenthic communities of four streams in the environs. The mine has not been closed yet, but there has been no mining and processing since 1990, and the research was carried out four years later. The quantity of some non-metal oxides and heavy metals in water exceeded the acceptable maxima levels for the second quality class, and concentrations of metals were approaching toxic concentrations in the stream under the mine. The density of macrozoobenthic organisms decreased, the number of taxa was reduced, some orders vanished completely. Some kilometres downstream the quality of the stream improved. Our research shows very clearly that the uranium mine has been still influencing the biocenoses of streams, but only in the nearest environs.
A systematic approach to optimal upgrading of water and waste water treatment plants
Authors: Rosén Björn , Morling Stig
Published: May 2018

Most of the future works in water and waste water treatment systems will involve the upgrading of existing facilities, for better performance and/or higher capacity. For the efficient implementation of any project, an upgrading strategy should be used, based on careful studies of the local conditions and the defined objectives to be reached.

The paper presents a systematic approach to upgrading with emphasis on treatment plant extension, without investing in large volumes, by more efficient use of existing facilities, illustrated by some cases. The importance of real competition in obtaining a cost-effective implementation is stressed.
Lab and pilot scale tests as tools for upgrading - comparison with full scale results
Authors: Malmqvist Åsa , Gunnarsson Lars , Torstenon Christer
Published: May 2018

Parameters such as hydraulic retention time, organic load, maximum COD removal, sludge characteristics and optimal nutrient dosage can be determined by simulation in small scale models of the chosen process. Laboratory tests are the natural first step when considering upgrading, or designing a new, biological treatment plant. The potential for a biological treatment can be examined at a low cost and within a minimum of time, often through parallel testing of different treatment methods. Once a suitable process configuration has been found, lab scale tests may well be used for optimizing the process and obtaining design data, thus minimizing the need for more expensive tests in larger scale. The principal reason for a pilot plant test is the possibility to investigate natural variations in wastewater composition and the effect this will have on process stability. The use of laboratory and pilot scale tests is here illustrated by the work carried out prior to the upgrading of the treatment plant at Nyboholm paper mill. A description of the upgraded full scale installation consisting of both chemical treatment and a suspended-carrier biofilm process is included and a comparison between results from lab, pilot and full scale treatment is made.
Upgrading of wastewater treatment plants for nitrogen removal: industrial application of an automated aeration management based on ORP evolution analysis
Authors: Caulet P. , Bujon B. , Philippe J. P. , Lefevre F. , Audic J. M.
Published: May 2018

Upgrading conventional wastewater treatment plants for nitrogen removal involves total control of nitrification, denitrification and carbon removal. On low-load activated sludge processes, a comprehensive survey on fast and low kinetic biological reactions has been carried out, which describes the short-term and long-term requirements on the aeration sequences in a single tank. Although soluble and adsorbed pollution have to be treated in routine conditions, soluble pollution treatment becomes a priority during limited overloads, indicated by a slow ORP evolution. The treatment of adsorbed material is hence delayed. In order to implement the appropriate strategy, an automated aeration management system has been developed. This system is based on the analysis of both the real time signal and time evolution of the Redox potential signal. This information is used for command and control purposes. The application of this logic-based approach at full scale has been fruitful in evaluating its adaptability to the industrial environment and its potential results. The operation of seven plants under the control of the automated management system has enabled the nitrogen removal performance to be increased. Most of the nitrification and denitrification yields reach 90%, whereas previous results were far lower and more erratic. In addition, the present work determines limiting conditions for a guaranteed long-term result and a successful upgrading.
Development of a new process for treatment of a pharmaceutical wastewater
Authors: Rosén M. , Welander T. , Löfqvist A. , Holmgren J.
Published: May 2018

In this study a process for biological treatment of toxic wastewater from a pharmaceutical company was developed. By simulations on a laboratory scale, the contribution of organic material and toxicity in wastewater from different sources was determined and the degradability of specific compounds were studied. The information obtained from these tests was used to improve the treatability of the wastewater at the sources. As an example a persistent organic phosphorous compound could be degraded after pre-treatment with chemical hydrolysis. By further simulations on a laboratory scale it was possible to screen through a large number of process configurations to determine the best working biological treatment. A combination of fungal and bacterial treatment was found to remove toxicity from the wastewater more than a conventional bacterial treatment. The results from the laboratory studies were confirmed in pilot tests. A full scale treatment plant, which design is based on the results from these studies are presently under construction.
Optimised particle separation in the primary step of wastewater treatment
Authors: Ødegaard Hallvard
Published: May 2018

Since the pollutants in wastewater to such a large extent are associated with particles, enhanced particle separation in the primary step of wastewater treatment should be aimed at. Space restrictions demand pretreatment options will a small “foot-print”. In this paper it is shown that coagulation with metal salts is very efficient but leads to excessive sludge production. It is demonstrated how the use of cationic polymers may reduce the sludge production considerably without ruining the SS-removal efficiency and also how improved flocculation, either chemically, by the addition of flocculants or physically, by improvement of settling tank design, may lead to better particle separation as well as smaller “foot-print” of the plant. As an alternative to primary settling, primary filtration in coarse, floating filters are discussed as well.
Treatment of stormwater to bathing water quality by dissolved air flotation, filtration and ultraviolet disinfection
Authors: Lainé S. , Poujol T. , Dufay S. , Baron J. , Robert P.
Published: May 2018

For the first time, a process for the treatment of urban stormwater has been designed in order to obtain treated water suitable for bathing activities. The degree of pollution removal is taken as far as the microbiological disinfection of the final effluent. This process, which combines air flotation, filtration and ultraviolet (UV) disinfection, has been tested at the pilot plant level in the eastern suburbs of Paris, France. The removal efficiency obtained on total suspended solids (TSS) and chemical oxygen demand (COD) through the flotation stage is close to 90% or better. The flotation facility has proved to be perfectly adapted to urban stormwater treatment with a maximal efficiency in the first minute of operation and with a TSS residual concentration consistently about 45 mg/L regardless of the variations in polluting loads entering the process. This is essential when taking into consideration the extreme variability of this load during rainfall. Sand filtration with a continuous washing system prevents operational interruptions during rainfall events. The UV disinfection process allows the microbiological contamination of the effluent to be reduced to a level in compliance with the regulations that define the quality of bathing water.
Particle separation as a pretreatment of an advanced drinking water treatment process by ozonation and biological activated carbon
Authors: Nishijima Wataru , Okada Mitsumasa
Published: May 2018

The role of particle separation on the performance of ozone-biological activated carbon (BAC) was evaluated based on the analyses of the fate of organic substances in the process. Pilot plant studies were carried out using eutrophic lake water as raw water. The ozonation not only converted refractory organic matter into biodegradable matter but also particulate organic carbon (POC) into dissolved organic carbon (DOC). Total decrease in adsorbable and non biodegradable DOC fraction (ADOC) after ozonation was only 16% of the influent into the biofiltration process followed by ozonation. However, the ozone-BAC process before membrane separation could reduce organic loading to membrane system. The smaller loading to microfiltration will result in long intervals of back washing and less frequent membrane fouling. Membrane separation before ozonation removed not only POC but also a part of DOC and could prevent dissolution of POC during ozonation. The decreases in ADOC by membrane and ozonation were 20% and 37% of the influent ADOC, respectively. The total decrease in ADOC for membrane process followed by ozonation was 57%. The separation of particulate matter will decrease loading of ADOC onto BAC significantly and, therefore, will extend service life of BAC.
Predicting solute transfer to surface runoff using neural networks
Authors: Lu Ruei-Shan , Lai Jiun-Liang , Lo Shang-Lien
Published: May 2018

In this study, a series of experiments were performed in a laboratory flume with a medium-packed bed. Surface runoff was controlled to pass at various flow rates, velocities, and runoff depths over the medium bed. Runoff samples were taken at the end of the flume, and the concentration of potassium chloride was analyzed. The relationships between the controlled input variables and the affected output variables was modeled using artificial neural networks (ANN). Many different ANN-architectures were investigated and this work shows that an optimum architecture with minimum RMS error at five hidden nodes was observed.
The sewerage system of Casablanca and the El Hank submarine outfall
Authors: Ludwig R. G.
Published: May 2018

After almost two decades of planning, the first major submarine outfall of Morocco is now in operation at the El Hank promitory of Casablanca. The paper provides details of the present and planned sewerage system with emphasis on the novel outfall construction method of the stabilizing system of the outfall.
Assessing management options for wastewater treatment works in the context of life cycle assessment
Authors: Dennison F. J. , Azapagic A. , Clift R. , Colbourne J. S.
Published: May 2018

This paper presents the preliminary results of a Life Cycle Assessment (LCA) study comparing different wastewater treatment works, operated by Thames Water Utilities Ltd. in the UK. Fifteen works have been studied, representing a range of size and type of treatment works. Five management regimes for centralising sludge treatment and disposal were analyzed in the context of LCA to provide guidance on choosing the best practicable environmental option (BPEO).

Consideration of Global warming potential indicates that the four proposed management regimes with centralisation of sludge for treatment and disposal, as adopted by Thames Water Utilities Ltd., is an environmental improvement upon the current practice. One of these options, that of complete centralisation and composting of sludge prior to disposal, exerts the least environmental impact with respect to Global warming potential. This suggests that the adoption of composting at Crawley is environmentally preferable to increasing the digestion facility at this works.
Estimation of regional intensity-duration-frequency curves for extreme precipitation
Authors: Madsen H. , Mikkelsen P. S. , Rosbjerg D. , Harremoës P.
Published: May 2018

Regional estimation of extreme precipitation from a high resolution rain gauge network in Denmark is considered. The applied extreme value model is based on the partial duration series (PDS) approach in which all events above a certain threshold level are modelled. For a preliminary assessment of regional homogeneity and identification of a proper regional distribution L-moment analysis is applied. To analyse the regional variability in more detail, a generalised least squares regression analysis is carried out that relates the PDS model parameters to climatic and physiographic characteristics. The analysis reveals that the mean annual number of extreme events varies significantly within the region, and a large part of this variability can be explained by the mean annual rainfall. The mean value of the exceedance magnitudes can be assumed constant for intensities with durations less than one hour. For larger durations a pronounced metropolitan effect is evident, the mean intensities in the Copenhagen area being significantly larger than found in the rest of the country. With respect to second and higher order moments the region can be considered homogeneous for intensities with durations less than 24 hours. A regional parent distribution is identified as the generalised Pareto distribution.
Temporal rainfall disaggregation based on scaling properties
Authors: Olsson J. , Berndtsson R.
Published: May 2018

The present study concerns disaggregation of daily rainfall time series into higher resolution. For this purpose, the scaling-based cascade model proposed by Olsson (1998) is employed. This model operates by dividing each rainy time period into halves of equal length and distributing the rainfall volume between the halves. For this distribution three possible cases are defined, and the occurrence probability of each case is empirically estimated. Olsson (1998) showed that the model was applicable between the time scales 1 hour and 1 week for rainfall in southern Sweden. In the present study, a daily seasonal (April-June; 3 years) rainfall time series from the same region was disaggregated by the model to 45-min resolution. The disaggregated data was shown to very well reproduce many fundamental characteristics of the observed 45-min data, e.g., the division between rainy and dry periods, the event structure, and the scaling behavior. The results demonstrate the potential of scaling-based approaches in hydrological applications involving rainfall.
Requirements for integrated wastewater models - driven by receiving water objectives
Authors: Rauch Wolfgang , Aalderink Hans , Krebs Peter , Schilling Wolfgang , Vanrolleghem Peter
Published: May 2018

The design of efficient technical measures for the abatement of water pollution requires that wastewater discharge regulations are driven by receiving water objectives. However, such integrated water quality management is only possible when the impact to the aquatic ecosystem can be predicted quantitatively by means of integrated wastewater models. Typically, only a few types of wastewater discharge impacts are relevant for the state of the receiving water and, consequently, the structure of the model can be kept relatively simple when focusing on one of these impacts. The procedure of problem-oriented model selection is illustrated for three typical examples of acute water pollution, that is toxicity from un-ionized ammonia, hygienic hazard from pathogenic micro-organisms and oxygen depletion.
Quality control of rain data used for urban runoff systems
Authors: Jørgensen H. K. , Rosenørn S. , Madsen H. , Mikkelsen P. S.
Published: May 2018

When improving software packages such as MOUSE and SAMBA for designing sewers and storage basins, and simulating overflows and flooding the quality of the input becomes important. The essential input to these modelling tools are the historical rain series. This paper presents the procedures for collection and quality control of rain data from a network of tipping bucket rain gauges in Denmark carried out by the Danish Meteorological Institute. During rain, the RIMCO gauge counts the number of tips (each of 0.2 mm of precipitation) every minute. The quality control of the rain data includes an automatic and a manual bit marking, where the automatic control basically is pointing out minutes with extreme intensities. In the manual control, the maximum intensities as well as the daily totals of precipitation are inspected, using weather charts, intensity plots and precipitation sums of nearby Hellmann gauges. Shortcomings and improvements of the quality control are discussed. Although, it is possible to improve the efficiency of the quality control, long term corrections will always be necessary.
Lake stratification and temperature profiles simulated using downscaled GCM output
Authors: Hassan Hany , Aramaki Toshiya , Hanaki Keisuke , Matsuo Tomonori , Wilby Robert
Published: May 2018

A mathematical in-lake water temperature model (WATEMP-Lake) was developed to investigate future responses of lake stratification and temperature profiles to future climate change due to rising concentrations of atmospheric greenhouse gases (GHGs). The model was used to simulate daily water temperature profiles and stratification characteristics in summer (June, July, and August-JJA) for Suwa Lake in Japan as a case study. For future assessments, the model uses surface climate variables obtained from a downscaling method that was applied to the UK Hadley Centre's coupled ocean/atmosphere model forced by combined CO2 and sulphate aerosol changes (HadCM2SUL). The downscaling method employed mean sea level surface pressure to derive three airflow indices identified as: the total shear vorticity (Z) -a measure of cyclonicity -, the strength of the resultant flow (F), and the overall flow direction (D). Statistical relationships between these indices and seven daily meteorological time series were formulated to represent climate variable series at sites around Suwa Lake. These relationships were used to downscale the observed climatology of 1979-1995 and that of 2080-2099 using HadCM2SUL outputs.
River water quality modelling: I. State of the art
Authors: Rauch W. , Henze M. , Koncsos L. , Reichert P. , Shanahan P. , Somlyódy L. , Vanrolleghem P.
Published: May 2018

River water quality models are used extensively in research as well as in the design and assessment of water quality management measures. The application of mathematical models for that purpose dates back to the initial studies of oxygen depletion due to organic waste pollution. Since then, models have been constantly refined and updated to meet new and emerging problems of surface water pollution, such as eutrophication, acute and chronic toxicity, etc. In order to handle the complex interactions caused by the increased influence of human activities in rivers it is today mandatory to couple river water quality models with models describing emissions from the drainage and sewerage system (such as the IAWQ Activated Sludge model No. 1). In this paper-which is the first of a three-part series by the IAWQ Task Group on River Water Quality Modelling-the state of the art is summarized with the above aim in mind. Special attention is given here to the modelling of conversion processes but also the methods and tools to work with the models, i.e. parameter estimation, measurement campaign design, and simulation software, are discussed.