bluuebunny/crossref_metadata_2025 huggingface dataset:
Soil and water changes after sewage irrigation practice in semi-arid region of Northeast Brazil
Authors: Lino de Araujo A. , Konig A. , Ceballos B.S.O.
Published: May 2018

Due to scarcity and uneven water distribution in many regions of the world, irrigation practices are carried using water with poor chemical and microbiological quality favouring salt accumulation in soil, groundwater contamination and health risks. These impacts can be easily evaluated with small soil columns, considered an equivalent experimental plots, given sufficient information for reuse practice such as plant water needs, water losses by evaporation and percolation, groundwater quality, culture productivity and microbiological contamination of soil and culture. This work describes chemical and microbiological changes in two soils of Paraíba State - Northeast Brazil, before and after irrigation with clean water and polluted superficial water. Also investigated are the changes in water quality before and after percolating these soil columns and lettuce (Lactuca sativa, L.) contamination. The analysed parameters in water were: pH, electrical conductivity, ions (calcium, magnesium, potassium, chloride and sodium), ammonia, total phosphorus, soluble orthophosphate, BOD, fecal coliforms (FC) and fecal streptococci (FS). The pH values for both irrigation waters were slightly neutral to alkaline. Electrical conductivity values were high in irrigation and percolating waters (up to 1,753 and 2,367 mmho/cm) due to waters and soil features, not affecting plant growth. The concentrations of calcium, magnesium, potassium were considered adequate for irrigation water but not for chloride and sodium, although indirect effects on lettuce growth were observed. The BOD5 of polluted water ranged from 8 to 15 mgO2/L and was reduced to 85% after the percolating soil columns. FCs in polluted water were well above the recommended WHO values of 1,000 CFU/100 mL with soils reducing these values in 99.8% for FC (2 × 106 - 4 × 103 CFU/100 mL) and 98% for FS (2.5 × 104 - 4 × 102 CFU/100 mL). Soils were highly contaminated with both FC (2.2 × 104 MPN/100 g) and E. coli (8.3 × 102 MPN/100 g) and when polluted water was used these numbers either increased or did not change. There was an increase of soil nitrogen and organic matter percentages after polluted water was added to the soils. Lettuces were also contaminated when both waters were used (with polluted water FC up to 2.0 × 105 MPN/100 g) and associated with aerosol formation during manual irrigation. Although some inconveniences are shown, water reuse must be considered as an alternative for food production in semi arid regions and will be successful when adequate and continuously technical support is given.
Forecasting peak demand - what do we need to know?
Authors: Day D. , Howe C.
Published: May 2018

Peak day demand is a key design parameter for assessing the future capital infrastructure needs of bulk water delivery systems. In addition, an understanding of peak demand is critical in designing demand management programs and establishing cost recovery pricing regimes. Despite the importance of peak demand on system design, little detailed research has been undertaken on developing approaches for forecasting peak demand. Accordingly, this paper identifies the non-climatic factors found to affect peak demand and examines changes in technology, land use and behaviour and their influence on peak demand forecasts. Furthermore, the paper contrasts several methods for forecasting peak demand by emphasising the advantages and limitations of each. The paper concludes by proposing an alternative methodology to forecast trends in peak demand through the creation of an innovative end use model for the residential sector. The limitations of the methodology and data requirements are discussed, as are the implications for designing peak demand management programs.
Public awareness and the environment: “How do we encourage environmentally responsible behaviour?”
Authors: Harvie M. , Jaques P.
Published: May 2018

This paper examines:• the relationship between environmental action and knowledge of the environment;• political, social and economic factors influencing the ability of individuals and societies to act in an environmentally responsible manner;• the possible motivations and contexts for encouraging greater responsibility toward the environment in various communities.

The annual National Environmental Education and Training Foundation (NEETF) Survey reveals that many US residents subscribe to environmental myths which may interfere with their efforts to act or agitate for environmental responsibility. Conventional wisdom might suggest that people in developing nations such as China would have a lower environmental awareness. In fact, when Shanghai residents were recently asked comparable questions to those in the NEETF Survey (part of an Asian Development Bank project), they often outperformed their American counterparts in their knowledge of environmental issues and in willingness to participate in activities such as recycling. - However in countries like China, changes are also required at an institutional level to make serious inroads into the problem of environmental degradation. In these circumstances, public awareness is a powerful tool only if the public has the power to drive institutional change. In many countries political influence constrains implementation of environmental projects with insufficient short-term political accolades. Similarly there are short-term economic and social goals that can dominate over the environment in the decision making process for both communities and individuals. This paper draws on USA, Australia and China survey data and the international experience of its authors in public awareness campaigns. The paper will discuss how environmental communicators can possibly change environmental attitudes and behaviour by understanding the contexts and the motivations for this change.
The environmental benefits of water recycling and reuse
Authors: Anderson J.
Published: May 2018

The world's supply of fresh water is finite and is threatened by pollution. Rising demands for water to supply agriculture, industry and cities are leading to competition over the allocation of limited fresh water resources. This paper examines how water reuse increases the available supply of water and enables human needs to be met with less fresh water. The paper is illustrated with water reuse case studies in agriculture, urban areas, industry and water resource supplementation in Australia and other countries. The links between water reuse and sustainable water management are examined. Water conservation and water reuse produce substantial environmental benefits, arising from reductions in water diversions, and reductions in the impacts of wastewater discharges on environmental water quality. Some examples are presented demonstrating the environmental benefits in quantitative terms. The paper also describes the economic and environmental benefits identified in a number of recent integrated water cycle planning studies in Australia.
Development of a web-based tool for the calculation of costs of different wastewater treatment and reuse scenarios
Authors: Sipala S. , Mancini G. , Vagliasindi F.G.A.
Published: May 2018

In this study a tool for the calculation of costs of different wastewater treatment and reuse scenarios has been developed. This tool, called Evaluation of Wastewater Treatment and Reuse Option (E-WA-TRO), was designed to have as end-users public administrators, water management authorities, and professionals that, in a direct and immediate manner, can automatically obtain, for a particular reuse alternative, the fundamental information for a feasibility study. In order to develop E-WA-TRO an overview was conducted of the international, national and regional regulations on water reuse and a synopsis of the possible reuse alternatives and of the appropriate treatment processes was prepared. Moreover, costs were obtained using national and international published data for the different treatment processes that might be required for the various reuse alternatives. The system has been created as a web site, in order to guarantee the highest availability and a wide diffusion and the possibility of an easy implementations of future updates and upgrades. Specifically, even non-expert user can easily navigate trough the site and use the tool to evaluate, within the national and international legal frameworks, various reuse alternatives as well as the appropriate treatment technologies and related costs.
Willingness of farmers to pay for reclaimed wastewater in Jordan and Tunisia
Authors: Abu Madi M. , Braadbaart O. , Al-Sa'ed R. , Alaerts G.
Published: May 2018

Despite water scarcity and high agricultural water consumption in the Middle East and North Africa region, substantial amounts of treated wastewater are discharged into seas without proper utilization. This can be attributed to either farmers' unwillingness to use or to pay for reclaimed wastewater. Therefore, a field survey was conducted in Jordan and Tunisia, which are considered as representative to the MENA region, using a prepared and pilot tested questionnaire. This study applies the contingent valuation method to elicit the willingness of farmers to pay for reclaimed wastewater. Logistic regression analysis is applied in an attempt to build a model that correlates qualitative responses of farmers to monetary stimuli. The water price seriously affects farming profitability and farmers' willingness to pay for reclaimed wastewater. Farmers prove to be unwilling to pay more than 0.05 $/m3 of reclaimed wastewater primarily because of quality concerns, comparatively easy access to freshwater, and price.
Pharmaceuticals and health care products in wastewater effluents: the example of carbamazepine
Authors: Stamatelatou K. , Frouda C. , Fountoulakis M.S. , Drillia P. , Kornaros M. , Lyberatos G.
Published: May 2018

Persistence and impact of pharmaceutics in the environment are discussed. The case of carbamazepine (CBZ), a widely used antiepileptic drug detected in rivers, lakes, sludges and even in ground water is examined. CBZ fate was investigated in all possible routes that may follow after it has been discharged to the sewage system: activated sludge, anaerobic digestion sludge, seawater, fresh water and soil. Carbamazepine slowed down, i.e. caused a decrease in the COD consumption rate in the activated sludge process, especially after longer term exposure, while the anaerobic sludge process was unaffected in the operating conditions that were applied. The compound was not degraded under either short term or long term exposure to either aerobic or anaerobic degradation processes. Carbamazepine seemed to biosorb to solid phases (soil, sludge) and this strength of sorption was related to the organic content of the solid phase. These results explain why CBZ is a very persistent xenobiotic compound, as is apparent from its detection in appreciable amounts in various aquatic environments.
Characterisation of volatile organic contaminants after different pretreatment systems in reclaimed wastewater
Authors: Romero J. , Ventura F. , Folch M. , Salgot M. , Torrens A.
Published: May 2018

Several lines of reclamation has been tested in the Palamós/Vall-Llobrega, Spain wastewater treatment plant (WWTP). Each line consists on a filtration treatment and a disinfection system. Different lines have been tested in order to establish the fate of volatile organic compounds (VOCs) during wastewater treatment and reclamation procedures. The studied technologies after a classical activated sludge treatment were infiltration-percolation, ring filtration, sand filtration, and coagulation-floculation plus sand filtration. Analysis of VOCs were performed at the different stages of the treatment by closed loop stripping analysis (CLSA) method which is able to determine compounds at trace levels (ng/L) and covers a wide range of organic pollutants. The CLSA extracts were further analyzed by GC/MS. Organic compounds such as tert-butyl alcohols and ketones, musks; iso-propyl fatty acids, and other minor components were regularly identified in the influent. Removal of all pollutants was partially achieved by all methodologies tested except the musk compounds which proved to be recalcitrant in all cases but one. The sole metodology that exhibited a total elimination of all organic compounds identified in the effluent including musks was infiltration-percolation.
Strategic water network rehabilitation planning
Authors: Herz R.K. , Lipkow A.T.
Published: May 2018

This paper presents the approach taken and the tools developed and advanced within the European research project CARE-W (Computer Aided REhabilitation of Water networks) for strategic rehabilitation investment planning as a complement to short-term performance monitoring and annual rehabilitation (rehab) budget allocation planning. In a first step, future rehab needs are quantified with a cohort-survival model from the present stock of assets taking into account the specific service lives of its components. Utility managers may choose in the short and medium range from many rehab options: doing more or less, sooner or later, on particular network components and with specific rehab technologies at lower or higher cost. So, in a second step, alternative medium-term rehab programs are specified and tested for their effects. The annual costs and benefits of these alternative rehab programs are forecast with the cohort-survival model beyond the rehab program period to capture the long-term effects of rehabilitating these long-lived assets. Advantages and disadvantages of alternative rehab programs are systematically compared to find out which one is most appropriate under local constraints. However, whereas the survival of network components can be forecast over very long periods with sufficient accuracy, many other characteristics of the water supply system that must be considered for finding the best network rehab strategy may take unforeseeable paths into the far future. Therefore, a scenario writing tool was developed allowing consistent scenarios for particular water utilities to be created and to test whether the alternative rehab programs are robust enough to meet all eventualities of the future. This approach is illustrated by a case study from East Germany.
Application of performance indicators to control losses - results from the Portuguese water sector
Authors: Cunha Marques R. , Monteiro A.J.
Published: May 2018

More and more the problem of water losses and leakages in water supply systems is becoming important in the management of water utilities. No matter how developed a country is, there is a growing and general awareness of this subject. Among the several motivations that contribute to this growing concern are, without doubt, the shortage of resources availability in several water supply systems on the one hand and, on the other hand, the economic value of the volume of water lost. Portugal is no exception. In recent years, there has been some dynamism in the sector in the accounting, control, leakages and loss detection, mainly in the biggest systems. This paper presents an approach to the control of water leakages and losses through the setting of performance indicators that allow the evaluation and characterization of the management entity for this aspect. Some results of those indicators will also be described here, as well as their application to several Portuguese water utilities and the assessment methodology of the results obtained. This paper also puts into evidence expressions and correlation curves between the different indicators and factors that directly or indirectly interfere in the result of the water utilities’ performance with relation to the water losses and leakages presented.
Applying the IWA approach to water loss performance indicators in Australia
Authors: Carpenter T. , Lambert A. , McKenzie R.
Published: May 2018

In 1999 and 2000, IWA Task Forces on Water Losses and Performance Indicators published their conclusions of over three years research, analysis and discussions. For the topics of Non-Revenue Water, Water Losses, Apparent Losses and Real Losses, these included:a recommended standard terminology, with definitions and procedures for assessing these components of the Annual Water Balance;recommended performance indicators for each of these components.

This work represents a major step forward in defining the “best practice” approach to assessing and presenting components of Non-Revenue Water, for more rational comparisons of performance in diverse systems within a single organisation, within the same country, and between countries. The 21 members of the Water Services Association of Australia (WSAA) provide water and wastewater services to 12.9 million Australians. WSAA seeks to promote “best practice”, and act as a national focus for all interested parties. In February 2000 WSAA organised a national Workshop in Melbourne to discuss the IWA methodology. Arising from this Workshop, WSAA commissioned the production of customised Software and an Associated User Manual known as “Benchloss”, to promote and facilitate the application of the IWA recommended methodology throughout Australia. The paper will describe the development and application of “Benchloss” to date, with a comparison of Australian performance data against an International Data Set used by the Water Losses Task Force.
Occurrence of Sphingomonas sp. bacteria in cold climate drinking water supply system biofilms
Authors: Vuoriranta P. , Männistö M. , Soranummi H.
Published: May 2018

Members of the bacterial genus Sphingomonas (recently split into four genera), belonging to α-4-subclass of Proteobacteria, were isolated and characterised from water distribution network biofilms. Water temperature in the studied network, serving 200,000 people, is less than 5°C for about five months every winter. Sphingomonads, characterised using fluorescent oligonucleotide probes and fatty acid composition analysis (FAME), were a major group of bacteria among the distribution network biofilm isolates. Intact biofilms, grown on steel slides in a biofilm reactor fed with tap water, were detected in situ using fluorescence labelled oligonucleotide probes (FISH). Hybridisation with probes targeted on α-proteobacteria and sphingomonads was detected, but FISH on intact biofilms suffered from non-specific hybridisation and intensive autofluorescence, possibly due to extracellular material around the bacterial cells attached to biofilm. These preliminary results indicate that bacteria present in the distribution network biofilms in this study phylogenetically differ from those detected in more temperate regions.
Application of web technology to enhance water system operations
Authors: Chapman A.
Published: May 2018

This paper explores the opportunities and recent applications of web-based technology, which have benefited water industry operations. Web-based technology can allow broad controlled access to all business data across the internal network (Intranet) of a water authority, by compact disc to mobile or remote stations and the broader internet. These web-based systems have significant advantages over traditional single-purpose databases and paper-based systems.
Investigation of factors contributing to dirty water events in reticulation systems and evaluation of flushing methods to remove deposited particles
Authors: Polychronopolous M. , Dudley K. , Ryan G. , Hearn J.
Published: May 2018

This investigation was to evaluate the factors contributing to dirty water customer complaints within the area supplied by South East Water Limited, a wholesale water company in Melbourne, Australia. It also evaluated the potential to derive a predictive method to facilitate proactive mains flushing. The study focused on a single reticulation network, within the suburb of Wantirna.

A desktop and field study were undertaken. The desktop study evaluated a range of parameters and their association with dirty water customer complaints over an 8-year period. Parameters evaluated included distance from the water source, street topography, population distribution, and variations in water velocity. The field investigation focused on evaluating the quantity of turbid material deposited in key locations, identified from the desktop investigations.

Several factors appeared to influence the likelihood of a dirty water complaint. These were: population density and the associated complexity of the reticulation network; the presence of an undulating topography in the street of concern; and the presence of a dead end.

Evaluation of hydrant flushing indicated there might be potential to reduce water usage and improve flushing efficiency by flushing at a reduced flow rate of 5L.s-1, down from the typical 10L.s-1 or higher currently used. Time to clear at a hydrant appeared to be the most effective measure of settled material in a water main, however more work is required to confirm a threshold value that could be used as a predictive measure for proactive mains cleaning.
LC-ESI/MS/MS analysis with derivatization applied to polar disinfection by-products in water treatment
Authors: Zwiener C. , Glauner T. , Frimmel F.H.
Published: May 2018

Chlorination and ozonation experiments under conditions close to drinking water treatment were carried out with two different tap waters with low DOC content and water from a bog lake with high natural organic matter content. THM formation was low and in the range of 10 μg/L. Derivatization with dinitrophenylhydrazine and HPLC/tandem mass spectrometry were applied to measure carbonyl DBPs by precursor ion scans at m/z 163 for aldehydes and at m/z 182 for dicarbonyls. Formaldehyde, acetaldehyde, glyoxal, and methylglyoxal were formed by chlorination and ozonation. Ozonation produced the highest levels of carbonyls, in particular in the tap water samples. A strategy for structure suggestion and identification of unknown compounds on the basis of collision-induced dissociation (CID) mass spectra (MS) is given. The resulting structures are carbonyls with additional hydroxy and carboxy groups and serve for choice or synthesis of standard compounds for further identification. The possibilities and limits of compound identification are discussed.
Determination of estrogenic short ethoxy chain nonylphenols and metabolites in river and treated water by SPE (solid phase extraction) and SPME (solid phase microextraction)
Authors: Díaz A. , Galceran M.T. , Ventura F.
Published: May 2018

Two solid-phase microextraction (SPME) procedures have been developed to determine short ethoxy chain nonylphenols and metabolites in water. A direct-SPME method has been used for the determination of short ethoxy chain nonylphenols and their brominated derivatives, whereas the in-sample derivatization headspace-SPME method has proved to be suitable for the simultaneous determination of short ethoxy nonylphenols and their acidic metabolites. Several parameters affecting both SPME procedures, such as extraction mode, fiber selection, extraction time, effect of organic modifiers, derivatization reagents and temperature, were optimized. Both methods were able to determine all these compounds at the sub-mg/L level and the results obtained were compared to a solid phase extraction method (SPE). The procedures developed were applied to raw and treated water from Barcelona (NE Spain).
Public or private “ownership” - what’s in a name?
Authors: Davis J. , Cashin G.
Published: May 2018

This paper examines the similarities and differences between public and private ownership of water utilities, including variations such as corporatisation. In any utility where the asset owner and the asset operator are the same, there are pressures to reduce operations and maintenance costs and capital expenditure to maximise returns. The authors argue that this is the case irrespective of whether such returns are to private shareholders or dividends to government. On the other hand, where the asset owner and the asset operator are separate entities with a clearly defined contractual interface, it is not possible to increase returns by reducing operations and maintenance standards, presuming a properly constructed contract. This is because the performance standards are clearly stipulated in the contract with payment reductions applying for non-performance. Such a model can be put in place irrespective of whether the asset owner is a private company or a public utility. The paper examines the profit incentive applying to private and public sector organisations in models where:the asset owner and the asset operator are the same organisation;models where the asset owner and the asset operator are separate organisations, with the service delivery performance governed by a clearly defined contractual interface.

The paper shows why the drivers governing the behaviour of public sector and private sector owners are similar, and how the separation of asset owner and asset operator can be used to ensure that service delivery standards are achieved at the lowest cost, whilst providing full transparency to shareholders, regulators and customers alike. The paper also reviews actual comparative data on service quality and performance under a number of ownership and contractual models, and draws conclusions on the effectiveness of the various asset owner/operator models in terms of service delivery performance and costs.
IAFECT™: a management tool to ensure effective technology training in the drinking water industry
Authors: Steynberg M.C. , Vermeulen A.
Published: May 2018

For years training was evaluated with measures such as numbers of participants, number of programs, length of programs, cost of programs and content of programs. These input focused measures have to be replaced by output focused measures. The output focused measures include learning profile and whole brain approach for the learner, competency requirements for the job, management’s role before, during and after training as well as the competency of the trainer and the effectiveness of the training environment. However, to ensure that the highest possible scores for these measures can be achieved, a multidisciplinary approach is of paramount importance. The purpose of this article is to demonstrate the IAFECT™ management tool designed to ensure effective technology training. IAFECT™ is a systematic approach that involves all stakeholders. It focuses on technical competence and a high Return-On-Investment.
Phosphorus removal with membrane filtration for surface water treatment
Authors: Dietze A. , Wiesmann U. , Gnirß R.
Published: May 2018

Surface water such as aquifers, recreational waters and rivers are often loaded by inflows with low quality, so that drinking water production, swimming or ground water charging must be restricted. To ensure the long-term use it is necessary to treat the influents or the water used for ground water charging. The current treatment process for phosphorus and turbidity removal is a combination of precipitation/coagulation, flocculation, sedimentation and sand filtration. By using this conventional method it is possible to reduce the dissolved ortho-phosphate and the turbidity (particulate phosphorus) as well as the amounts of algae and pathogenic organisms to very low concentrations. The high degree of reduction in this process is only achieved by a relatively high dosage of coagulants and flocculants. Such a process has been used for nearly 20 years by the Berliner Wasserbetriebe. In this study a comparison will be made between this process, which represents the state-of-the-art, and the combination of precipitation/coagulation with dead-end membrane filtration (micro-/ultrafiltration) concerning water quality and costs. The results show that it is possible to reach similar levels of phosphorus removal as with floc filtration. However, floc filtration requires significantly higher amounts of chemicals (coagulants and flocculants). No flocculants are used for membrane filtration. But the estimated costs for the membrane based process are at 0.17 €/m3 probably a little more expensive. However, the excellent permeate quality is much better at the values of suspended solids and micro-biological organisms.
Solar thermal driven desalination plants based on membrane distillation
Authors: Koschikowski J. , Wieghaus M. , Rommel M.
Published: May 2018

In arid and semi-arid regions the lack of drinkable water often corresponds with a high solar insolation. These conditions are favourable for the use of solar energy as the driving force for water treatment systems. Especially in remote rural areas with low infrastructure and without connection to a grid, smallscale, stand-alone operating systems for the desalination of brackish water from wells or salt water from the sea are desirable to provide settlements with clean potable water. Fraunhofer Institut für Solare Energiesysteme is currently developing a solar thermally driven stand alone desalination system. The aim is to develop systems for a capacity range of 0.2 to 10 m3/day. Technical simplicity, long maintenance-free operation periods and high quality potable water output are very important aims for successful applications of the systems. The separation technique that the system is based on is membrane distillation. The implemented heat source is a corrosion-free, sea water resistant thermal collector.
Removal of trichloroethylene and trichloroethane using a novel hollow-fibre gas-permeable membrane
Authors: Takizawa S. , Win T.
Published: May 2018

In order to evaluate effects of operational parameters on the removal efficiency of trichloroethylene and 1,1,1-trichloroethene from water, lab-scale experiments were conducted using a novel hollow-fibre gaspermeable membrane system, which has a very thin gas-permeable membrane held between microporous support membranes. The permeation rate of chlorinated hydrocarbons increased at higher temperature and water flow rate. On the other hand, the effects of the operational conditions in the permeate side were complex. When the permeate side was kept at low pressure without sweeping air (pervaporation), the removal efficiency of chlorinated hydrocarbon, as well as water permeation rate, was low probably due to lower level of membrane swelling on the permeate side. But when a very small amount of air was swept on the membrane (air perstripping) under a low pressure, it showed a higher efficiency than in any other conditions. Three factors affecting the permeation rate are: 1) reduction of diffusional boundary layer within the microporous support membrane, 2) air/vapour flow regime and short cutting, and 3) the extent of membrane swelling on the permeate side. A higher air flow, in general, reduces the diffusional boundary layer, but at the same time disrupts the flow regime, causes short cutting, and makes the membrane dryer. Due to these multiple effects on gas permeation, there is an optimum operational condition concerning the vacuum pressure and the air flow rate. Under the optimum operational condition, the residence time within the hollow-fibre membrane to achieve 99% removal of TCE was 5.25 minutes. The log (removal rate) was linearly correlated with the average hydraulic residence time within the membrane, and 1 mg/L of TCE can be reduced to 1 μg/L (99.9% removal).
Formation and prevention of hardly removable particle layers in inside-out capillary membranes operating in dead-end mode
Authors: Panglisch S.
Published: May 2018

Although numerous ultra- and microfiltration dead-end plants with capillary membranes are already operative, some phenomena are still unexplained. Therefore, the fundamental processes taking place inside a capillary membrane were observed. Initially, the flow field depending on axial and radial position inside the capillary was determined. Then, particle transport and deposition were theoretically studied by determination of particle trajectories considering influences of particle concentration and walleffects on hydrodynamics, DLVO-forces, buoyancy, gravitation, diffusion and interparticular forces. Following these calculations, incoming particles with a diameter smaller than the so-called “limiting diameter”, which depends on operational and geometrical boundary conditions, due to depositions are widely and evenly distributed. Larger particles do not deposit until they are at a certain distance from the water inlet. The larger the particle size, the longer the distance. If the particle is larger than the so-called “corkforming diameter” then the particles are transported to the dead-end of the capillary which may cause a clogging of the capillary. This “corkforming diameter” depends on operational as well on geometrical boundary conditions. These theoretical predictions are confirmed by experimental results from investigations with spherical latex and non-spherical walnut particles. To avoid this clogging, the deposition of the particles should be evenly distributed, which means that the “corkforming diameter” should be as large as possible. That goal could be achieved by operating the membrane plant with short and/or wide capillaries. However, a small permeate flux, a small membrane resistance and/or a small membrane surface potential succeed as well. Another possibility could be to operate the capillaries with a very small cross flow.
Enhanced pre-coat engineering (EPCE®) for micro- and ultrafiltration: steps to full-scale application
Authors: Galjaard G. , Kruithof J.C. , Scheerman H. , Verdouw J. , Schippers J.C.
Published: May 2018

Ultrafiltration of surface water without pre-treatment frequently suffers from high fouling rates and irreversible fouling. Enhanced pre-coat engineering (EPCE) has been developed with the aim to enable ultrafiltration plants to treat surface water directly at high and stable flux rates. In this study in-line coagulation with ferric chloride and polyaluminium chloride and EPCE are compared on pilot scale using capillary membranes with IJssel Lake water as feed water. The in-line coagulation experiments resulted in relatively low flux rates and irreversible fouling, whereas EPCE enabled us to achieve a flux rate of 100 l/(h.m2) and a dosage of less than 25 g/m3. However, a couple of technical questions need to be answered before fullscale application can be implemented with all types of ultrafiltration systems.
Understanding membrane fouling: a review of over a decade of research
Authors: Laîné J.-M. , Campos C. , Baudin I. , Janex M.-L.
Published: May 2018

Since the first membrane applications at the end of the 1980s, the water treatment engineering community has been able to develop reliable low pressure membrane systems that are capable of producing high quality drinking water at a competitive price, making membrane technology an attractive solution to both upgrade existing plants and design new ones. A competitive price means low capital and operating cost, which are inversely proportional to membrane hydraulic performance (permeate flux). Porous membranes lose their hydraulic performance as materials accumulate on their surfaces and/or within their pores, a process called membrane fouling. Although a significant effort has been devoted to elucidating the fouling mechanisms of polymeric membranes by natural organic matter (NOM), no single model has yet been accepted. In fact, most of the existing literature is contradictory, showing that membrane fouling is far from being fully understood. This article reviews over a decade of Ondeo's experience on characterizing and preventing fouling of polymeric membranes by natural organic matter and inorganic compounds. The review focuses on the role of NOM size and hydrophobicity, of membrane chemistry, and of solution pretreatment (coagulation and/or adsorption). In addition, the efficacy of some currently used strategies to minimize membrane fouling is also discussed.
Handling of membrane concentrate from reclamation of water in polyester dyeing
Authors: Villanueva A. , Wenzel H. , Knudsen H.H.
Published: May 2018

This analysis presents the results of a study carried out on 6 alternative options for the disposal of membrane reject (concentrate) from a Danish polyester dyehouse. The options analysed comprise: discharge to sewer (reference option and current practice), transport to biogas followed by sludge incineration, wet air oxidation, activated carbon, transport to hazardous waste treatment facility, and drying for zero-discharge. In most disposal scenarios considered it is advantageous to dewater the concentrate further from 2.5%DS (dry solids) to 20%DS in order to reduce its volume and thereby diminish the transport costs. Membrane filtration is a technology competitive to evaporation for dewatering at moderate DS contents that avoid the effects of fouling. The results obtained help concluding that discharge to sewer and biogas treatment are the less expensive options, as long as the concentrate is free of pollutants that may disturb the treatment process or jeopardize further applications of the biodegraded residue. Total dewatering of the concentrate for zero liquid discharge is still the most expensive solution. The results obtained confirm that concentrate disposal is a major cost of industrial water recycling projects where the concentrate has low or no commercial value. In the scenarios analyzed, concentrate disposal costs represent between 10% and 70% of the total treatment costs per m3 of water recycled. It is therefore recommended to analyze in detail the available alternatives for concentrate disposal in order to identify these costs at an early stage of the projects.
Rejection mechanisms of plastic additives and natural hormones in drinking water treated by nanofiltration
Authors: Agenson K.O. , Oh J.I. , Kikuta T. , Urase T.
Published: May 2018

Rejection mechanism of nanofiltration (NF) membrane for organic solutes (including alkyl phenol, bisphenol A, phthalate acid esters, phosphoric acid esters, other plastic additives, and natural hormones like 17β estradiol, etc) was examined. The experiments indicated almost complete removal of these solutes by the tight NF membranes, while the rejection obtained by the loose membranes was dependent on solute species. Compounds with flat-shaped structure like 2-H-benzothiazol and dimethyl phthalate were more permeable than other target solutes within the same molecular size range. Of the four methods of size determination used, there was no significant difference in the accuracy of prediction of rejection from the solute sizes. The size configurations of molecules have been identified to greatly influence the permeation or retention, yet the size parameter was thought to be incomplete as a single parameter in describing rejection of organic solutes. The logarithm of octanol-water partitioning coefficients of solutes appears not to be an effective parameter in modelling rejections as its contribution was only slight or minor. We obtained better correlations with structural configuration of molecules (by molecular width and length) and polarity of the molecules.
Coagulation-adsorption-ultrafiltration for wastewater treatment and reuse
Authors: Abdessemed D. , Nezzal G. , Ben Aim R.
Published: May 2018

We considered the treatment of domestic wastewater by coagulation–adsorption–ultrafiltration, and a test of adsorption like pre-treatment to the membrane as an alternative for wastewater reclamation and reuse. The performances of two inorganic tubular membranes (M2 and M5 CARBOSEP with 15,000 Da and 10,000 Da MWCO) were studied. Powdered activated carbon was used as adsorbent agent and FeCl3 as a coagulant. Coupling adsorption and ultrafiltration resulted in satisfactory results: the efficiency of COD removal was increased by using PAC compared with results obtained when using only UF membranes.
Air sparging backwash in ultrafiltration hollow fibres for drinking water production
Authors: Guigui C. , Mougenot M. , Cabassud C.
Published: May 2018

Air sparging was applied to improve backwash efficiency for an ultrafiltration inside/out hollow-fibre module operating in dead-end mode. Air was injected into the retentate side only during the backwash period. The filtration experiments were performed on a semi-industrial scale pilot using a clay suspension as a model of surface waters. The backwash procedure consisted of two steps: in a first step (phase A), air was added to the feed water inside the fibre lumen at the bottom of the module. In a second step (phase B), cleaned water backwash was performed. Different air velocities were used and the kinetics of particle removal were studied with turbidity measurements of backwash waters. The experimental results showed that using an air–fluid mixing allows one to increase the quantity of particles removed from the hollow fibres. For the phase A, the removed mass is higher when the air velocity and duration of air injection increased. But, even at very low air velocity (0.08 m/s), a high backwash efficiency was observed. Experiments with filtration/air-sparging backwash cycles concluded that using air–fluid mixing in the backwash sequence allowed prevention of long-term fouling and reduced the rate of fouling during the filtration period.
Measurement of effective shear stress working on flat-sheet membrane by air-scrabbling
Authors: Nagaoka H. , Tanaka A. , Toriizuka Y.
Published: May 2018

This study is aimed at elucidating the mechanism by which rising air bubbles induce shear stress on a vertically set flat plate. Shear stress was directly measured changing air flow rate and viscosity of water. The time-series data showed strong fluctuation sometimes showing downward direction values (opposite to bubble flow direction). Time-averaged shear stress values were approximately double the water flow induced shear stress values in all experimental conditions. Histograms of the shear stress variation data were fitted well to the normal distribution curve and mean plus three times of standard deviation was chosen as “maximum” shear stress value, which means “effective” shear stress for the detachment of substances off the membrane surface. The “effective” shear stress value increased with the increase of air flow flux and increased also with the increase of viscosity. Especially in the highest viscosity condition (15 mPa s), the value showed quite large values probably due to the interacting force between the wall surface and large bubbles that were produced by the effect of highly viscous liquid.
Treatment of high sulfate and high strength wastewater in a single stage anaerobic reactor
Authors: Huang J.-C. , Kumar Khanal S.
Published: May 2018

In this study, a preset oxidation-reduction potential (ORP) was employed to regulate oxygen dosing for online sulfide toxicity control during anaerobic treatment of high sulfate wastewater. The experiment was conducted in an upflow anaerobic reactor (UAF), which was operated at a constant influent total organic carbon (TOC) of 6740 mg/L (equivalent to a chemical oxygen demand (COD) of 18000 mg/L) but with different influent sulfates of 1000, 3000 and 6000 mg/L. The reactor was initially run without oxygen injection at a natural ORP of about −290 to −300 mV and then was followed by oxygenation to raise ORP by +25 mV above the natural level for each influent sulfate level. With 1000 and 3000 mg/L influent sulfates, the produced sulfide levels did not impose any appreciable toxicity to methanogens even without oxygen injection. However, with 6000 mg/L influent sulfate without oxygen injections, the dissolved sulfide level quickly went up to over 800 mg/L which imposed a significant suppression on methanogenesis. Upon oxygen injection to raise the ORP by +25 mV, the dissolved sulfide was quickly reduced to 160 mg/L. If more oxygen was injected to raise the ORP by +50 mV, then dissolved sulfide further decreased to 12.2 mg/L with a concomitant improvement in methane yield by 45.9%.

With a +25 mV preset ORP increase, it was found that at the 1000 mg/L influent sulfate the supplied oxygen was more than that needed for sulfide oxidation. The excess oxygen could be utilized readily by facultative heterotrophs for organic oxidation, which contributed 13.5% of the total COD removal in the UAF. At the higher sulfate levels of 3000 and 6000 mg/L, the facultative contributions to the total COD removal were only 4.7 and 4.1%, respectively. This study has clearly demonstrated that ORP is a workable and reliable means for regulating oxygen injection to achieve online sulfide toxicity control in a single-stage anaerobic system treating high sulfate wastewater.
Towards sustainable urban stormwater management
Authors: Boller M.
Published: May 2018

New directives for the management of urban stormwater prioritize infiltration and direct discharge into receiving waters. This requires innovative new stormwater facilities in urban areas. Besides hydraulic requirements for retention and infiltration capacity, the pollutants contained in the runoff water are of primary importance in future stormwater drainage concepts. Different urban surfaces are classified according to their potential for pollutant wash-off and the most crucial substances in view of hazardous effects in the aquatic and terrestrial environment are identified. Source control of hazardous pollutants by choosing alternative materials for the construction of buildings, roads and vehicles is considered to be most sustainable but will only be effective on a longterm perspective. In addition, new facilities for decentralized hydraulic retention combined with barrier systems for the most hazardous substances are proposed allowing for ecologically safe discharge of the stormwater into the local environment. Soil passage and new adsorber systems in the form of different granular adsorbents have been investigated and turned out to represent efficient retention systems which can well be integrated into infiltration and hydraulic retention facilities. It is suggested that the structures for stormwater handling are integrated into local landscaping in the surrounding of buildings in the form of ponds, reed-beds, ditches, etc. creating attractive blue-green environments.
Use of Anammox in urban wastewater treatment
Authors: van Loosdrecht M.C.M. , Hao X. , Jetten M.S.M. , Abma W.
Published: May 2018

Nitrogen removal is the most complicating factor in urban wastewater treatment. Nitrification accounts for more than 50% of the oxygen need and requires long sludge ages. Denitrification is often hampered by a lack of COD. In fact it would be better to use this COD to generate methane. Recent research has shown that it is possible to remove ammonium by anaerobic ammonium oxidation leading to a much reduced need for aeration energy, no need for COD in the N-removal, and a considerable lower sludge production. The state of the art and the potential role in urban wastewater treatment are discussed.
A pilot plant study using ceramic membrane microfiltration, carbon adsorption and reverse osmosis to treat CMP (chemical mechanical polishing) wastewater
Authors: Lo R. , Lo S.-L.
Published: May 2018

Currently, most semi-conductor plants adopt the conventional chemical coagulation and sedimentation process to treat chemical mechanical polishing (CMP) wastewater. This treatment process consumes a large quantity of coagulants, and its optimum pH operation range is rather narrow. This treatment process produces huge amounts of sludge and is hard to operate due to the unstable characteristics of the abrasive slurry of CMP wastewater. The purpose of this research is to establish a pilot plant which consists of chemical pretreatment, ceramic membrane microfiltration, carbon filtration and reverse osmosis system, which will allow the reclamation of the CMP wastewater. Actual CMP wastewater was sampled and treated in the pilot plant. The results of the pilot tests demonstrated the viability of the treatment scheme and provided data for scale-up calculations. Cost per ton of CMP wastewater reclaimed was calculated using the operating data established, and compared with the conventional chemical coagulation and sedimentation process.