bluuebunny/crossref_metadata_2025 huggingface dataset:
Drinking water treatment in The Netherlands: outstanding and still ambitious
Authors: Hofman J.A.M.H. , Ijpelaar G.F. , Heijman S.G.J. , Vrouwenvelder J.S. , Kruithof J.C. , van der Meer W.G.J.
Published: May 2018

Water treatment in The Netherlands has developed to an outstanding level. Nevertheless, new challenges, such as protozoa (e.g. Cryptosporidium), Legionella, endocrine disrupting compounds and pharmaceuticals, have to be faced. These challenges can have a negative effect on customer confidence and the overall reputation of water supply. The Dutch water supply companies therefore have set a new ambition for water quality. To realize this ambition an integral approach to water treatment involving new technologies as membrane filtration and UV is necessary. The paper will present the possibilities of the current level of technology, how it relates to the vision and ambition of the Dutch drinking water sector and the role of research – especially in UV technology and membrane filtration – in realizing long-term goals.
UV degradation of carbofuran insecticide in aqueous solution: identification and toxicity evolution of by-products
Authors: Mascolo G. , Lopez A. , Detomaso A. , Guzzella L.
Published: May 2018

The paper reports the results of an investigation about the UV degradation of carbofuran, a widely used insecticide in Europe. Specific objectives were the identification of the by-products formed and the evaluation of the toxicity of the irradiated solution compared to that of carbofuran. The experimental results, obtained treating an aqueous carbofuran solution (50 mg/L) by high pressure UV lamp (125 W), show that the insecticide is completely removed within 120 min. Several intermediate by-products have been identified by liquid chromatography-mass spectrometry (LC-MS) as a result of hydroxylation process of the 2,3-dihydro benzofurane ring and other reactions such as the cleavage of the carbamate group, the hydrolysis of ethereal moiety, radical coupling and decarboxylation processes. After 270 min of reaction the identified by-products were completely degraded and COD and TOC removals of 35 and 20% were measured, respectively. Toxicological analyses performed using the comparison procedure of the MicrotoxTM assay provided interesting clues concerning toxic effects of the photodegradation by-products. The results revealed a substantial increase of the toxicity during the first 15 min proving that photodegradation of organic contaminant could even lead to an increase of the toxicity of treated solution.
Residual chlorine management in water distribution systems using network modelling techniques: case study in Seoul City
Authors: Ahn J.C. , Kim Y.W. , Lee K.S. , Koo J.Y.
Published: May 2018

Twelve sampling locations in a network from a water treatment plant to consumers' taps were selected for measuring residual chlorine loss, THMs, TOC, etc. and 24 hour sampling in the locations was conducted on a bimonthly basis for one year. Chlorine bulk decay and THM formation tests were carried out by bottle tests under controlled temperatures for three locations: a water treatment plant, a large service reservoir, and a pumping station. Water quality modelling of chlorine loss in the distribution system was performed using data collected in the field study. This study contributed to the improvement of chlorine management in the distribution system by providing information for operators to maintain a minimum level of chlorine residual in a service reservoir.
Investigation of introducing water from an artificial recharge plant to an existing groundwater distribution system
Authors: Berg R.L. , Jensen T.Ø. , Bennedsen L. , Brandt G.
Published: May 2018

The consequences of mixing water from the Arrenaes Artificial Recharge (AR) trial plant with groundwater from existing well fields have been investigated. The potential problems of interest are bacterial regrowth, precipitation of iron, and corrosion in the raw water distribution system. The AR trial plant is located on the Arrenaes peninsula on Zealand, Denmark. A large-scale production plant for drinking water (4 million m3/year) is proposed at the locality. To test the microbial properties of the mixed water, laboratory experiments have been carried out. Based on the results, it has been concluded that introducing water from the proposed large-scale AR plant to the distribution system will not cause problems with undesirable regrowth of bacteria in the pipelines, as long as the content of AOC in the abstracted AR water stays within the current range, between 3 and 15 μg/L. Chemical modelling (PHREEQC) shows that the mixed water is supersaturated with iron oxides, which may precipitate as iron sludge. Furthermore, the model shows that the hardness of the water in the pipelines will decrease when abstracted AR water is added. This is not expected to cause corrosion, due to a simulated supersaturation with calcite in all water types. However, long-term operation of the proposed large-scale AR plant, and thereby leaching of calcite from the aquifer, may lead to corrosion of the pipelines.
Municipal wastewater reclamation: where do we stand? An overview of treatment technology and management practice
Authors: Bixio D. , De heyder B. , Cikurel H. , Muston M. , Miska V. , Joksimovic D. , Schäfer A.I. , Ravazzini A. , Aharoni A. , Savic D. , Thoeye C.
Published: May 2018

Water reclamation implementation and management practices at municipal wastewater treatment plants throughout the world are reviewed and some implementation and operational issues are defined. The information is based on a conventional literature survey, on an in depth survey study of European, Israeli and Australian medium and large-scale water reclamation utilities and on the findings of a dedicated international workshop.

The review identified over 3,300 water reclamation projects and designed the map of the main process technologies and their fields of product water application. The main conclusion of the enquiry is that the technological risks no longer represent a major concern for the development of water reclamation projects, rather issues such as the financing, failure management and social acceptance have become more critical.
Evaluating citizens concern about the quality of their drinking water
Authors: Contu A. , Carlini M. , Maccioni A. , Meloni P. , Schintu M.
Published: May 2018

Citizens' concern about the quality of their drinking water stems especially from poor or wrong information. A tool allowing consumers to consult the Internet for the “label characteristics” of the tap water they are drinking, and to look for general information on water for human consumption has been developed. The tool allows to carry out online queries contributing to optimising management and using the water resource. Thanks to the implementation of an experimental protocol in secondary schools in Sardinia (Italy), it has been possible to test the efficacy of the tool by adapting its content to a large scale of users and to carry out a didactic-educational drill on the theme of water resources. To assess the weight of the aesthetics (taste, colour, and odour) in determining the degree of acceptability of the water, two tests were carried on both resident and non-resident assessors. This study allowed to survey the perception of the general public and the concerns arising from them.
Removal of bromate, perchlorate and nitrate from drinking water in an ion exchange membrane bioreactor
Authors: Matos C.T. , Velizarov S. , Crespo J.G. , Reis M.A.M.
Published: May 2018

The presence of anionic micropollutants, such as bromate, perchlorate and nitrate, in drinking water supplies represents a risk for public health. This work evaluates the applicability of the ion exchange membrane bioreactor (IEMB) concept for their removal. The IEMB concept combines the transport of anionic pollutants, through a dense mono-anion permselective membrane, with their simultaneous biodegradation to harmless products by a suitable microbial culture in a separated biocompartment. The transport of the pollutant counter-ions (anions) is governed by the Donnan equilibrium principle and, therefore, it is possible to enhance it by using a more concentrated driving counter-ion (e.g. chloride) added to the biocompartment. The IEMB process proved to selectively remove nitrate and perchlorate to concentrations below the recommended levels of 4 ppb for ClO4− and 25 ppm of NO3−, from a model polluted stream containing 100 ppb of ClO4− and 60 ppm of NO3−. Transport studies, made under Donnan dialysis conditions, showed bromate fluxes comparable to those obtained for nitrate under similar experimental conditions. However, the rate of biological reduction of bromate was about one order of magnitude slower than that of nitrate.
Dosing ratios for reduced bromate formation by dissolved ozone dosing
Authors: van der Helm A.W.C. , Smeets P.W.M.H. , Baars E.T. , Rietveld L.C. , van Dijk J.C.
Published: May 2018

Bromate formation experiments were carried out in a 100 l/h bench-scale dissolved ozone plug flow reactor (DOPFR) with natural filtered water from the drinking water treatment plant Leiduin of Amsterdam Water Supply at gross ozone dosages of 0.7–3.4 mg/l. In the DOPFR, ozone is dosed by intensively mixing a dissolved ozone water flow (side stream) with a test water flow (mainstream). The side stream is pre-treated to remove bromide and DOC and to lower the pH. For full-scale application of the DOPFR concept, it is most cost effective to apply the smallest possible side stream. This research is done to establish the effect of decreasing the ratio of the dissolved ozone side stream to the mainstream from 1:10 to 1:25, by increasing the ozone concentration and decreasing the flow of the side stream. The results show that the dosing ratio has no influence on the bromate formation in the ozone dosing range of 0.7–1.4 mg/l. The gross ozone dosages that are currently applied at the drinking water treatment plant Leiduin are 0.8–1.0 mg/l. This means that for application of dissolved ozone dosing at Leiduin the amount of ozone that can be dissolved in the side stream will be the limiting factor for the minimal flow of the dissolved ozone side stream.
Ion exchange equilibria of arsenic in the presence of high sulphate and nitrate concentrations
Authors: Baciocchi R. , Chiavola A. , Gavasci R.
Published: May 2018

The aim of this work was to develop a quantitative description of the ion exchange equilibria of arsenic on a strong anionic resin, in the presence of nitrates and sulphates. First, the ion exchange equilibrium data of As(V) and NO3− on a strong anionic resin in chloride form were obtained and described with a model based on the mass action law. Namely, assuming ideal behaviour for both solution and resin phase, the thermodynamic constant of the As(V)/Cl− and NO3−/Cl− ion exchange equilibria were estimated by fitting of experimental data. Then, these equilibrium constants were used to predict the ion exchange behaviour of the ternary system As(V)/NO3−/Cl−, providing a rather good agreement with experimental results. The ion exchange equilibria involving sulphate ions were also studied, showing a very high affinity to the resin phase. This behaviour did not allow a quantitative robust modelling of the equilibrium pattern. The results discussed in this paper represent a first step toward the development of a comprehensive modelling of the ion exchange process for the removal of As(V) from surface and groundwater in the presence of competitive, naturally occurring anions.
Effectiveness of high-silica zeolites for the adsorption of methyl tertiary-butyl ether from natural water
Authors: Knappe D.R.U. , Campos A.A. Rossner
Published: May 2018

MTBE adsorption isotherm data were collected for a matrix of high-silica zeolites with different pore sizes (ZSM-5/silicalite, mordenite, beta, Y), exchangeable cations (H+, Na+, NH4+), and hydrophobicities (SiO2/Al2O3 ratios). MTBE adsorption capacities of high-silica zeolites were compared with those of one coconut-shell-based and two coal-based granular activated carbons (GACs) as well as a carbonaceous resin. Isotherm experiments were conducted in ultrapure water buffered at pH 7.2 and in Tar River water (Greenville, NC) to determine the effects of co-adsorbing and preloaded natural organic matter (NOM) on MTBE adsorption. The results of this study showed that (1) high-silica zeolites with small pores (ZSM-5/silicalite, mordenite) exhibit higher MTBE adsorption capacities than GACs, (2) NOM has little or no effect on MTBE adsorption capacities of ZSM-5/silicalite zeolites, and (3) equilibrium model results suggest that silicalite-based adsorption systems are cost-competitive with activated-carbon-based adsorption systems while offering operational advantages such as longer adsorber life and possibly greater ease of regeneration.
Repair and regrowth of Escherichia coli after low- and medium-pressure ultraviolet disinfection
Authors: Hu J.Y. , Chu X.N. , Quek P.H. , Feng Y.Y. , Tan X.L.
Published: May 2018

Ultraviolet (UV) light disinfection has increasingly been used as an alternative method to replace conventional chlorine disinfection as it has been found to be a more efficient disinfection method. As UV disinfection only damages the nucleic acids of the microorganisms to prevent replication, there is a possibility of microorganisms repairing the damage sites. As few studies have investigated the reactivation of microorganisms after exposure to medium-pressure UV disinfection, it is essential for reactivation related to medium-pressure UV disinfection to be studied as medium-pressure lamps are gaining in popularity. Besides, disinfection by-products (DBPs) produced by UV disinfection have been discovered recently and may serve as a carbon source in the finished water, resulting in regrowth of the bacteria. It is therefore important to know the regrowth potential of bacteria with the existence of DBPs. In this study, the repair and regrowth of Escherichia coli after UV disinfection were investigated. Results showed that E. coli underwent photo repair (up to 5 log under fluorescent light conditions) more significantly than dark repair (up to 0.8 log in terms of bacterial count increase). The repair was generally found to be higher at low doses. At the same UV dose, it seems medium-pressure UV irradiation is able to control the repair to a lesser extent. In addition, the bacterial regrowth potential was studied with the addition of DBPs typically found in UV processes, such as acetic acid and formaldehyde. The maximum increase in bacterial count was found to be 0.3 log. Generally, the level of regrowth was insignificant compared with the increase of bacterial count due to bacterial repair.
Effects of water tariff structures on water demand in Tokyo metropolis
Authors: Takizawa S. , Iwasaki C. , Oguma K.
Published: May 2018

As the socio-economic structure of Tokyo has changed over the last few decades, the water demand also has changed significantly. The bulk customers who use larger amounts of water gradually diminish, and the number of single and small households has increased dramatically. Analysis of the impact of such changes is necessary to give a clearer idea on the future water demand. In this paper, the effects of water tariff revision in 1994 on water consumption were analysed. Using the data obtained from Tokyo Metropolitan Waterworks, it was proved that the total annual water consumption after the change of water tariff structure in 1994 decreased significantly compared to the preceding years. The decreasing trend, however, started two years before the water tariff revision, which coincides with the downturn of the Japanese economy. In order to further analyse the contribution of customers classified by monthly water consumption, the numbers of customers in all water consumption classes were analysed for the years 1994 and 2001. The analysis on changes of the numbers of customers in each water consumption class revealed that the most significant reduction in water consumption took place in a water consumption class IV (31–100 m3/month), which comprises small businesses and large families. The reduction of water consumption by bulk customers with monthly water uses greater than 100 m3 was not so significant. The reduction in water consumption by medium to large users was partly augmented by the increasing number of single and small family users.
Water supply reservoirs vigilance program in Seville (southwest Spain): a useful tool for active water resource management
Authors: Díaz A. , Basanta A. , Escot C.
Published: May 2018

With nearly 30 years' experience of managing stored surface water for water supply, the Municipal Water and Sewage Company of Seville (EMASESA), has introduced a Water Supply Natural Resources Vigilance Program. It consists of four levels that are mutually complementary: early warning system; vigilance of raw water resources; research; and integration of limnological knowledge. Selecting the reservoir that should be used, intake depth, transfer strategies, etc, are some examples of active management that this Vigilance Program allows us to achieve. Guaranteeing high quality raw water resources, at all times, which therefore favours their treatment, is one of the priority objectives for EMASESA. This is because it not only has repercussions from an economic point of view but it also contributes to the efficient and sustainable use of water resources.
Using measured microcomponent data to model the impact of water conservation strategies on the diurnal consumption profile
Authors: Kowalski M. , Marshallsay D.
Published: May 2018

A recent collaborative research project by the Water Research Centre (WRc), involving 13 water companies and the UK Environment Agency, has yielded further information on the microcomponents of water use in domestic properties in the UK. Investigating the uncertainty and diurnal variations of the data has allowed the investigation of demand reduction strategies at household and supply area levels. The paper expands on these issues and discusses how this approach can be used to help plan and manage water supply in the future.
Disposal of Sewage Sludge to Sea – Engineering Aspects
Authors: Greer W T
Published: May 2018

The selection of the sewage sludge dumping site in the Firth of Clyde off Garroch Head is compared with the selection of sites near Bell Rock and St. Abbs Head off the Forth Estuary, Scotland, almost three-quarters of a century later. Details are given of the special shore facilities which are required to dispatch sewage sludge to sea, and specific features of purpose built sludge ships are described. Reference is then made to the factors involved when discharging sludge at the sea dumping site. The emphasis in the paper is on the engineering aspects of the facilities required and operations involved in the sea disposal of sewage sludge.
Technical Control of Sewage Sludge Disposal to Sea
Authors: Cockburn A G
Published: May 2018

Technical control of sewage sludge disposal to sea is carried out primarily to maintain the quality of the receiving environment and this paper discusses the control in the context of England and Wales. Control is exercised in several ways and by several bodies. There are international conventions and national legislation governing sludge dumping, the national legislation is enforced by the Ministry of Agriculture Fisheries and Food, who stipulate the required quality and quantity of sludge. The sludge is produced and disposed of by regional water authorities who must control the quality of their sludge and use trade effluent legislation to control effluent from industry. In turn industrialists must control their effluents to meet water authority standards and this usually requires the installation of water treatment equipment or even change of process. At all stages scientific methods are used to check the effect of the legislative control. It is important that the technical controls used to protect the environment are not over-stringent so that an economic and practicable method of sludge control is not wasted.
Effects of Turbulent Suspension on Trajectories of Settling Particles
Authors: French J A
Published: May 2018

In many ocean dumping cases, settleable solids are introduced at the sea surface, fall through the water column, and come to rest on the sea bed a significant horizontal distance from the dump point. Classical stream sedimentation analysis is extended to the case of net downward sediment flux to describe three regimes of particle settling: (a) unaffected by turbulence, (b) influenced by turbulence, (c) dominated by turbulent diffusion. A procedure for computing particle trajectories is presented.
Disposal of Sludge to Sea†
Authors: Neilson H R
Published: May 2018

†This paper should be included in Theme 1A - Legislation.
Organic Micropollutants in Effluent Recharge to Groundwater
Authors: Clark L , Baxter K M
Published: May 2018

Groundwater pollution by organic material derived from the recharge of raw, untreated sewage effluent has been studied at the sewage treatment works at Whitchurch in Hampshire. This organic investigation consisted of two parts; the validation of the sampling and analytical techniques and the field investigation.

Sampling points for the survey included open boreholes lined with uPVC or mild steel as well as specially designed buried in-situ groundwater samplers of uPVC or stainless steel construction. Laboratory leaching tests show significant pollution of sampled water by nylon and uPVC components and indicate that all plastics must be avoided in sample point construction. The in-situ samplers with stainless steel bodies and PTFE sampling tubes proved satisfactory.

The organic field survey showed that the organic pollution plume is coincident with the inorganic plume from the effluent recharge site. The total organic content of the effluent is reduced through infiltration; 85 per cent is removed in the unsaturated zone and a further 14 per cent during 300 m of lateral flow. The number of organic compounds at significant concentrations also is greatly reduced through infiltration. The most persistent micropollutant identified as coming solely from the sewage is dichlorobenzene which is present at about 9 µg/l below the recharge lagoons and 1 µg/l in the pollution plume 300 m from the site.
Elimination of Organic Micropollutants
Authors: Hultman B
Published: May 2018

The elimination of organic micropollutants from water and wastewater may be done by separation methods, which are useful to concentrate and relocate pollutants so that they can be more readily recovered or destroyed, or by destruction and detoxification methods by which the pollutants are destroyed and detoxified by the use of oxidation or reduction. Both these principal methods are discussed with a special emphasis on similarities between treatment techniques, prediction methods of removal efficiencies and treatment of priority pollutants.
Methodology of Research in Micropollutants – Heavy Metals
Authors: Wollast Roland
Published: May 2018

A comparison of the concentration of dissolved and of particulate heavy metals in the aquatic system indicates that these elements are strongly enriched in the suspended matter. The transfer between the aqueous phase and the solid phase may be due to dissolution-precipitation reactions, adsorption-desorption processes or biological processes. When these processes are identified, it is further possible to develop mathematical models which describe the behaviour of these elements. The enrichment of heavy metals in the particulate phase suspended or deposited and in aquatic organisms constitutes a powerful tool in order to evaluate sources of pollution.
Methodology of Research Concerning Micropollutants: Biological Tests
Authors: Poels C L M , van der Gaag M A , Noordsij A
Published: May 2018

To obtain insight into the toxicological quality of polluted waters a broad range of test methods is available. Because of the wide variability in biological effects caused by the substances present in a complex polluted water, a well considered choice of biological methods is recommended. These biological methods should be supported by, and if possible strongly integrated with, chemical analysis. For detection of harmful effects of water containing numerous pollutants in low concentrations, longterm as well as embryo/larval tests with rainbow trout are applied to measure chronic toxic effects. The very important genotoxic effects however are missed by these tests. For this purpose Sister-Chromatid exchange tests with eastern mud-minnows and Amestests are performed. Especially the last test can be fully integrated with analytical chemical methods. Thereby it will be possible in the near future to identify the mutagenic substances and to track down their origin.
Single Sludge Nitrogen Removal from Industrial Wastewater
Authors: Argaman Y
Published: May 2018

Nitrogen removal by the single-sludge nitrification and denitrification process offers several economic advantages over the multi-sludge systems. This paper provides a description of the processes involved, and a discussion of some chemical and kinetic aspects with emphasis on industrial applications. A relatively simple design procedure is presented using zero order kinetics for nitrogenous subtrates removal and first order kinetics for carbonaceous organics removal. The solution is obtained by a trial and error calculation procedure. Finally, two examples are presented of operating systems treating industrial wastewater. One example is a bench-scale study of an amino acid production wastewater and the other is a full-scale plant treating wastewater from a combined pharmaceutical-pesticides-herbicides processing. Both systems effectively reduce the concentration of carbonaceous organics, ammonia and nitrate to very low levels.
The Rehabilitation of Norway's Largest Lake
Authors: Baalsrud K
Published: May 2018

Lake Mjøsa, situated in the southeast of Norway, is the largest lake in Norway. Originally it was an oligotrophic lake, rich in oxygen down to its deepest part, 449 m below the surface and 328 m below sea level. In the period after 1950 signs of eutrophication developed reaching a maximum in the mid-1970's with the mass occurrence of filamentous blue-green algae. Comprehensive investigations have yielded data on the physical, chemical and biological characteristics of the lake. The trophic state is well described by the Vollenweider model. A phosphorus control program was suggested and made possible through Government funds. The Ministry of Environment organized a campaign which began in 1977 and which already seems to give the results expected.
The River Tame – A Short History of Water Pollution and Control Within an Industrial River Basin
Authors: Harkness N
Published: May 2018

Pollution of the River Tame from the late nineteenth century to date has been followed and observations made on the administrative and technical steps which have led to the recent return of fish after a period of over 60 years.
Environmental Impact of the Microbial Aerosol Emissions from Wastewater Treatment Plants
Authors: Lue-Hing C , Zenz D R , Sedita S J
Published: May 2018

The literature on microbial emissions from wastewater treatment plants is reviewed and a major study of microbial aerosol emissions from such a plant is described and discussed.

The literature was found to be repleted with studies which showed that microbial aerosols are emitted from wastewater treatment plants but rapid die-away was shown once the aerosols reach the ambient air. Epidemiological studies of wastewater treatment plant workers and of communities nearby such plants gave overwhelming evidence to show that wastewater treatment plants do not affect the health of the local populace nor the plant workers themselves.

The paper describes a major study of the microbial aerosol emissions of a waste-water treatment plant operated by the Metropolitan Sanitary District of Greater Chicago. In this study, it was found that aerosols containing microorganisms were emitted from the aeration tank surface at rates of 208 to 386 standard plate counts per cubic meter of air at a distance of 0.3 m above the surface. However, it was found that there was rapid die-away of microbial emission with distance from the aeration tanks both horizontally and vertically.

It was concluded, based upon the literature review and the major study described, that microbial aerosol emissions from wastewater treatment plants were not a significant factor in the health of the surrounding populace.
New Methods for Analyzing Water Pollutants
Authors: Keith L H , Hall R C , Hanisch R C , Landolt R G , Henderson J E
Published: May 2018

Two new methods have been developed to analyze for organic pollutants in water. The first, two-dimensional gas chromatography, using post detector peak recycling (PDPR), involves the use of a computer-controlled gas Chromatograph to selectively trap compounds of interest and rechromatograph them on a second column, recycling them through the same detector again. The second employs a new detector system, a thermally modulated electron capture detector (TMECD). Both methods were used to demonstrate their utility by applying them to the analysis of a new class of potentially ubiquitous anthropoaqueous pollutants in drinking waters- -haloacetonitriles. These newly identified compounds are produced from certain amino acids and other nitrogen-containing compounds reacting with chlorine during the disinfection stage of treatment.
Operational Management of Pollution Incidents–The Thames Way, United Kingdom
Authors: Reed E C , Dart M C
Published: May 2018

Total river basin management in the U.K. offers an opportunity to respond to emergency situations in a unified and effective way. Thames Water, the largest of the ten Regional Water Authorities in England and Wales, U.K. has established procedures for dealing with pollution and other operational emergencies - these are outlined and a case history of a pollution incident is examined in relation to the effectiveness of the procedures, the lessons learnt and the continuing benefits gained from actions taken at the time. Current development of a facility to overcome oxygen depletion in a tidal reach of the River Thames is outlined.
Viability and Adaptability of E. coli. and Enterococcus Group to Salt Water with High Concentration of Sodium Chloride
Authors: Omura T , Onuma M , Hashimoto Y
Published: May 2018

Some experiments were carried out to examine the adaptability of E. coli. and enterococcus group to salt water with high concentration of sodium chloride after the experiments on viability in this salt water.

Unlike E. coli. type I, when E.coli. type II was repeatedly exposed to salt water, the survival of E.coli. type II was changed from rapid extinction to multiplication as the experiments went on. At the same time, it was also made clear by means of the IMViC test that E.coli. type II was replaced by Citrobacter freundii as E.coli. type II adapted itself to salt water.

The enterococcus group was separated into four distinct types; S. faecalis, S. faecalis var. liquefaciens, S. faecium and S. durans. The results of the experiments on viability in salt water indicated that S. faecalis var. liquefaciens possessed the greatest viability, and S. faecium the weakest. From the results of the experiments on adaptability, it was found that each type of enterococcus group had a different adaptability to salt water. In spite of the weakest viability, S. faecium could adapt itself to salt water as well as S. faecalis and S. faecalis var. liquefaciens. On the other hand, S. durans could not adapt itself to salt water at all.
Impact of Nuclear Power Plants of the Pwr-Type on River Water Quality (Case-Report of the River Meuse)
Authors: Masschelein W J , Genot J
Published: May 2018

Five years' experience with data of the TAILFER plant located 48 km downstream of the nuclear power site of GHOOZ is reported so as to provide guidelines for the examination of future nuclear cases.

The factors considered are: the reduction in water flow and thermal impacts, the discharge of nuclear active effluents and the physico-chemical impact of enrichment in salts and suspended matter.

Primary importance must be given to the proportion of the discharges in terms of added (instantaneous) volume activities. In the case of inland rivers the most active effluents, including the particular isotope tritium, are contained in a reduced volume (1400 m3/l000 MWe), and are best evacuated to other sites.

Guidelines to check the river water quality are based on the measurement of 3H, total γ, and especifically, Go60, Cs13737, Mn54, Co58, and Cs134.

Flow measurement and river transfer modelling must be part of the study of the impact as illustrated by this case-report.
A Comparative Study of Methods for Concentration of Human Enteroviruses from Sewage
Authors: Martins M T , Marques E , Soares L A
Published: May 2018

A study has been undertaken to determine a suitable method for virus isolation from sewage samples in Sao Paulo State, Brazil. The samples were concentrated by the following methods: adsorption on aluminum hydroxide flocs; precipitation by aluminum sulfate; adsorption to and elution from membrane filters followed by organic flocculation; direct organic flocculation as a single-step concentration method and electropositive cartridge filter, AMF Cuno. The BS-C-1 cell line and the plaque technique were used for virus assay.

Out of the methods employed, the Al(OH)3, method presented the best recovery rates (185.6 PFU), followed by AMF Cuno method (58.0 PFU), organic flocculation as a second-step concentration method (40.6 PFU), direct organic flocculation (24.3 PFU) and adsorption on Al2SO4). (6.0 PFU). From a total of 1,037 viruses isolated, 176 strains were identified: 110 were Coxsackie B virus (62.5%), 57 were poliovirus (32.4%) and 7 were Echovirus (4.0%). Two virus strains remained untyped.
Development of Water Reclamation Technology in South Africa
Authors: Clayton A J , van Vuuren L R J , Roux B
Published: May 2018

In South Africa, full-scale research on the technology of reclamation of drinking-water from wastewater was focused on two 4,500 m3/d plants. The Stander water reclamation plant (SRP), Pretoria, served as a research demonstration facility, initially treating biofilter humus tank effluent, which necessitated high lime treatment and ammonia stripping. Research findings and process development at the SRP were implemented to modify the Windhoek water reclamation plant (WRP), which was originally designed for maturation pond effluent after conventional biofilter treatment. High ammonia concentrations as a result of progressive overloading of the sewage works hampered continuous production of reclaimed water. Activated sludge secondary effluent which became available at both sites ensured low residuals of ammonia and a higher quality effluent more suitable for reclamation purposes. The high lime process was successfully replaced by coagulation with metal salts at both plants, with the application of interstage chlorination between the two clarification stages. This process modification significantly improved operating costs and simplified operational control. Results obtained over a 12-month period for the Windhoek plant form the main subject of this paper.
Optimization of Nitrogen Removal in the Single Sludge Activated Sludge Process
Authors: van Haandel A C , Dold P L , Marais G v R
Published: May 2018

Optimal design of nitrification-denitrification (N-D) systems reduces to obtaining maximum denitrification subject to the constraint of efficient nitrification. Under constant flow and load conditions simple approximate highly accurate formulae are developed to describe the N-D system. Selection of the N-D configuration is found to be crucially influenced by the TKN/COD (influent) ratio, µnm, maximum and minimum temperature and sludge age. In terms of these factors design charts are presented which rapidly allow the best configuration and sizes of the anoxic and aerobic reactors to be selected.
Characterization of Fouling Potential for Pressure-Driven Membrane Processes: A New Simulated Flow Cell
Authors: Reed R H , Belfort G
Published: May 2018

Membrane systems are unit processes that are becoming widely accepted for the demineralization of saline and other waste waters. Dissolved and particulate material, specifically colloidal matter, present in the feed stream to membrane systems are considered the principal causes of membrane fouling and reduced efficiency. Conventional water analysis do not yield the information needed to determine the amount of fouling that will occur. Therefore, some rapid indication of the water quality and its potential to foul is needed.

Presently there are five tests available to evaluate feed-water quality for membrane processes. However, in each of these tests the apparatuses used do not model tangential (shear) flow across the membrane surface. Therefore, a new apparatus was designed and constructed to predict how the feed water foulants would behave in a flow field.

A new apparatus, named the Simulated Flow Cell (SFC), was developed and tested in the laboratory with feed waters containing polystyrene latex spheres (PSL) as foulants and in the field with well-water and precholorinated secondary effluent. The SFC reproduced essentially the same results as the standard non-flow cell when operated under the same conditions. However, the SFC was also able to model flow regimes to membrane systems.

The Simulated Flow Cell was tested using irradiated polycarbonate membranes with pore diameters ranging from 0.1 µm to 1.0 µm. The feed water turbidity was varied during the testing by the addition of PSL spheres. Varying these parameters permitted data collection under a wide range of conditions. For laboratory feed water with the addition of PSL spheres, a theoretically expected threshold velocity was observed with the SFC using 0.1 µm pore diameter membranes. The threshold axial velocity was directly proportional to the square root of the initial flux through the 0.1 µm Nuclepore membranes, which is in agreement with data collected from actual hyperfiltration plant operations.

The Simulated Flow Cell is a low cost apparatus for the rapid characterization of permeator feed waters. The Simulated Flow Cell promises to become an important tool in the ever widening use of membrane processes in water and wastewater applications.
A Mathematical Model of Biological Purification in Aerated Activated Carbon Biofilters
Authors: Martin G , Le Roux A-Y , Schulhof P
Published: May 2018

On the basis of results obtained in the laboratory and in a semi-industrial pilot, this paper outlines the probable mechanism of biological purification on activated carbon. It shows that with small loads, the medium's porosity plays a permanent role in the treatment of a water. The biological activity which develops on the material acts in a complementary fashion, allowing for continuous regeneration of the activated carbon's pores.

With heavy loads, there are two phases. During the first, adsorption and biological regeneration are complementary. This phase lasts three to four hours. During the second phase, development of the biomass obstructs the occurrence of the adsorption phenomenon.

Substrate is removed on the surface. This second phase lasts from fifteen to twenty hours, until the filter is clogged. After washing, the first phase again enters into operation.

A mathematical model is presented. It describes results obtained with small and heavy loads.
Granular Activated Carbon and Preozonated Granular Activated Carbon Treatment for Biologically and Physically-Chemically Treated Wastewater Effluents
Authors: Netzer A , McNutt J L
Published: May 2018

The Duck Creek Wastewater Treatment Plant is a combined municipal-industrial wastewater treatment facility serving a municipal population of over 200,000 and an industrial community of over 600 various light industries. This 30 MGD treatment facility operates in a split-stream mode, with 7.5 MGD treated by biological processes and 22.5 MGD treated by physical-chemical processes. Final treatment for both systems is supposed to consist of granular activated carbon treatment and chlorine disinfection.

Problems in operation and implementation of the granular activated carbon systems for the combined biological and physical-chemical treatment effluents prompted The University of Texas at Dallas to design and construct a pilot plant facility composed of 5 pilot plant systems. This facility provides for evaluation of granular activated carbon (GAC) treatment and preozonated granular activated carbon (POGAC) treatment for biologically, physically-chemically, and blended (biologically and physically-chemically) treated wastewater effluents simultaneously. The UTD-Duck Creek Pilot Plant Facility has been operating since November, 1979, demonstrating the improved operation and treatment efficiency of preozonated granular activated carbon treatment for biologically, physically-chemically, and blended wastewater effluents.

In addition to improved treatment efficiency demonstrated by the preozonated granular activated carbon systems, average operational life prior to bed exhaustion was extended from an average 70 days for GAC to over 300 operational days for POGAC.
The Adsorption Behaviour of Cationic Polyelectrolytes in Dissolved Air Flotation
Authors: Gehr R , Henry J G
Published: May 2018

This study examines the adsorption behaviour of polymers of various molecular weights (MW) in dissolved air flotation (DAF) systems. Batch and full scale DAF tests were done using activated sludge. Residual polymer was measured by a titri-metric method, and Zeta potential (ZP) measurements of the effluent were also made. Two highly charged cationic polyelectrolytes of different MW were used.

In batch tests, the two polymers yielded similar performance in terms of effluent and float solids concentrations, but slightly less high MW polymer was needed to attain low effluent SS. In both cases, polymer residual was detectable only when polymer doses beyond that needed for lowest effluent SS were applied. Significant increases in float solids concentration also occurred only at the higher doses. Polymer adsorption followed the Langmuir isotherm behaviour. Higher MW polymer adsorbed in larger quantity, indicating that the polymer “monolayer” was not flat on the surface of the sludge particles. ZP reversal (to a positive value) occurred only when polymer residual was detected, not at the polymer dose required for lowest effluent SS. Results were confirmed with full scale tests.

A model for polymer-induced flocculation is presented, suggesting that polymer attachment occurs by attraction of opposite charges, but that bridging of colloids occurs to cause incorporation in the float. It is indicated that the cationic condition in the float at excess polymer dose causes exclusion of water in favour of air bubbles, and hence a more concentrated float.
The Use of Water Quality Models in Management Decision Making
Authors: Barnwell Thomas O. , Krenkel Peter A.
Published: May 2018

The use of water quality models in three management contexts is described: screening, planning, and design. Screening models are illustrated by describing a methodology applicable to large areas of land and another applied to a large number of chemicals. The application of models in a planning context is illustrated by a local planning agency's use in developing nonpoint source control strategies and by the federal government's use in assessing potential exposure to a pesticide. Development of design criteria is illustrated by summarizing the long history of model use to develop effluent limits in the Holston River basin (Tennessee).
Water Recycling – Industrial Applications
Authors: Albrecht D R , Imhoff K R
Published: May 2018

The application of industrial water recycling techniques is demonstrated by examples of various industrial branches such as: steel production, pickling and plating, coal mining and coking, sulphite cellulose and paper production, sugar works, and power plants. Special consideration is given to water recycling in metal finishing works and paper mills.
The Location and Nature of Accumulated Phosphorus in Activated Sludge
Authors: Buchan L
Published: May 2018

Electron microscopy and energy dispersive X-ray analysis was used to demonstrate that granules in Acinetobacter contained in excess of 25 % (m/m) phosphorus with a Ca:P ratio between 0.15 and 0.36. Accumulation was possible under continuous aerobic culture and was enhanced by the presence of fermentation products from raw sewage.
Precipitation of Calcium Phosphate and Ph-Effects in Denitrifying Biofilms
Authors: Arvin E , Kristensen G H
Published: May 2018

The poster illustrates the results from the project “Precipitation of Calcium Phosphate and pH-effects in Denitrifying Biofilms. It explains why the pH inside fixed biofilms may be significantly higher or lower than in the bulk liquid and some effects of this. The high pH which may be created as a result of denitrification reactions can initiate calcium phosphate precipitation. The verification of both the pH-effect and the phosphate precipitation is shown through photos by an interference contrast microscope, electron microscope, though chemical analysis data and simultaneous pH-measurements in both the bulk liquid and the rear of the biofilm. The equipment used is shown through photographs and schematic drawings. Finally the perspectives of the research is delineated.
German Practice in Land Disposal of Sludge Including Legislation and Health Aspects
Authors: Möller U
Published: May 2018

This paper describes the German practice in land disposal of sludge, including legislation and health aspects, and past, present and future policy.
Distribution of Enteric Viruses and Microorganisms in Long-Term Sewage-Treated Soil
Authors: Filip Z , Seidel K , Dizer H
Published: May 2018

To determine whether long-term sewage treatment can take place without a pollution risk for soil and groundwater, samples from sewage irrigation fields in West Berlin which have been in use since about 1890 were analyzed for enteric viruses and microorganisms. Enteric viruses were detected in only seven samples from a total number of eighty seven taken from different soil depths. With only one exception, no viruses were found below 60 cm. No viruses were detected in groundwater samples. Long-term sewage irrigation did not result in significant changes in the colony courts of aerobic soil bacteria, but the counts of anaerobic bacteria and actinomycetes were slightly elevated and those of microscopic fungi slightly decreased. Potentially pathogenic bacteria were not detected in soil below 90 cm.
Thermal Discharge and Fish Fauna in Sweden
Authors: Neuman Erik
Published: May 2018

Investigations on the fish fauna have been performed at four thermal power plants in Sweden situated on Lake Mälaren, the Baltic, the Sound and the Kattegatt. The results illustrate effects of thermal discharge in various salinities, from fresh water to above 20‰. The presentation is based on material from several years of test fishing with gill nets and fyke nets.

The most common species have been classified as warm- or cold-water fishes on the basis of the catch/temperature relationship. The reactions towards the cooling-water mainly correspond to this grouping. Exceptions due to special hydrographic conditions and to the supply of food are discussed.

Shallow bottoms in freshwaters and at the Baltic coast are massively dominated by warm-water species of freshwater origin, while marine cold-water fishes hold a strong position in the higher salinities of the Sound and the coast of the Kattegatt. The effects of thermal discharge upon the species composition are thus demonstrated to increase with the salinity.