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Papers by Maarten Nederlof

Research paper thumbnail of Integrated multi-objective membrane systems application of reverse osmosis at the Amsterdam Water Supply

Desalination, 1998

Within the scope of a project funded by AWWARF and USEPA three very promising IMS&amp... more Within the scope of a project funded by AWWARF and USEPA three very promising IMS's were identified for surface water treatment. This paper will cover some highlights of the research carried out by Amsterdam Water Supply (AWS) and Kiwa on the combination of biological activated carbon filtration, slow sand filtration and (ultra low pressure) reverse osmosis. Primary objectives of this

Research paper thumbnail of Bioavailability of heavy metals in terrestrial and aquatic systems: A quantitative approach

Environmental Toxicology and Chemistry, 1999

... the pH and calcium concentration (as a competitor for the same sorption sites as the metal io... more ... the pH and calcium concentration (as a competitor for the same sorption sites as the metal ion) are considered two of the most important factors that affect the distribution ... With the help of these equations, the distribution of the metal over the biotic and abiotic components in ...

Research paper thumbnail of Comparison of NF/RO membrane performance in integrated membrane systems

Desalination, 2000

Within the framework of the project ‘Integrated multi-objective membrane systems for control of m... more Within the framework of the project ‘Integrated multi-objective membrane systems for control of microbials and DBP precursors, funded by AWWARF and USEPA, four integrated membrane systems (IMSs) for surface water treatment were investigated. The identified IMSs are based on pretreatments including slow sand filtration, bank filtration, coagulation-sedimentation-rapid filtration (CSF) and ultrafiltration respectively. The IMSs were tested on three locations in

Research paper thumbnail of Analysis of ion binding on humic substances and the determination of intrinsic affinity distributions

Analytica Chimica Acta, 1990

are characterized by a vanabIe ekctnc potential and by a vanety of bmdmg sites Ieadmg to chenucal... more are characterized by a vanabIe ekctnc potential and by a vanety of bmdmg sites Ieadmg to chenucal heterogeneity Bmdmg of ions to these substances 1s Influenced by both factors A methodology based on acid-base tltratlons at several salt levels IS presented that allows for the assessment of an appropriate electrostatic double-layer model and the mtrmslc proton affuuty dlstnbutlon The double-layer model 1s used for the conversIon of pH to pHs for each data pomt, where Hs 1s the proton concentration m the diffuse Iayer near the bmdmg site. It 1s shown that with an appropnate double-layer model the proton bmdmg curves at different salt levels converge mto one '*master curve" when pIotted as a function of pHs. The mtnnslc proton affmlty dlstnbutlon can then be denved from the "master curve" using the LOGA method. A ngorous analysis of metal bmdmg to hurmc substances is complex and m practice 1s not feasible. Under two different (slmphfymg) assumptions, namely fuIIy coupled and uncoupled bmdmg, It 1s shown how mtnnslc metal ion affuuty dlstnbutlons can be obtamed Mode1 calcutatlons show that apparent metal ion affuuty dlstnbutlons do not resemble the mtnnslc metal Ion affinity dlstnbutlon.

Research paper thumbnail of Quick-Scan: Selection of micro- and ultrafiltration membranes

Desalination, 1998

ABSTRACT

Research paper thumbnail of Heterogeneity analysis for binding data using an adapted smoothing spline technique

Environmental Science & Technology, 1994

Heterogeneity analysis is a helpful tool to select a proper model for the description of ion bind... more Heterogeneity analysis is a helpful tool to select a proper model for the description of ion binding to polyfunctional ligands. Two approaches of heterogeneity analysis are discussed: the local isotherm approximation (LIA) method and the differential equilibrium function (DEF) method. For both methods, the approximate distribution function of a given ligand system is a series of derivatives of the experimentally obtained binding function. To obtain reliable derivatives, a smoothing spline routine is adapted for the present problem. The smoothing parameter of the spline is determined by a generalized cross-validation criterion in combination with physical constraints derived from the binding function. With the thus obtained spline function, the distribution is calculated. Error bars for the obtained distribution function can be calculated using the variance in the spline function. The error bars indicate whether peaks in the distribution are significant. The methodology is applied to a synthetic data set to illustrate its capabilities and limitations and is applied to copper binding to humic materials (data set of Hansen et al.) to illustrate its use in practice. The quality of the calculated distribution function depends on the experimental error in the data, the number of data points, and the binding range. On the basis of the calculated distribution function, a binding model can be selected.

Research paper thumbnail of Analysis of the binding heterogeneity of natural ligands using adsorption data

Cheminform, 1992

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was e... more ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Research paper thumbnail of Integrity of membrane elements, vessels and systems

Research paper thumbnail of Desalination of brackish groundwater: the concentrate dilemma

Desalination, 2005

Vitens uses ground water from deep confined aquifers as one of her drinking water sources. These ... more Vitens uses ground water from deep confined aquifers as one of her drinking water sources. These sources have an excellent raw water quality due to the absence of anthropogenic contaminants. However, the wells are susceptible for upconing of brackish groundwater. As a result several wells had to be abandoned leading to a reduced production capacity. Recently the ‘fresh holder’ concept was introduced by Kiwa Water Research to solve this problem. It is not clear yet if this concept is allowed and if there are any technical problems. In order to investigate both the technical and political implications of the described concept a demonstration project is set up near the city of Deventer. The first step is to see whether the required permits can be obtained. Since this is a new application, the discussion with the authorities will be started in an early stage.

Research paper thumbnail of Feasibility of micro- and ultrafiltration for the direct treatment of surface water: results of various pilot studies

Research paper thumbnail of Twenty years of experience with central softening in The Netherlands: Water quality - Environmental benefits - Costs

Central softening has been utilized by the Dutch water utilities since the late 1970s. It was int... more Central softening has been utilized by the Dutch water utilities since the late 1970s. It was introduced in the water treatment process as a method to supply water with an optimum water composition to prevent lead and copper release and to prevent excessive scaling. Twenty years of experience show that central softening is beneficial for public health, has significant environmental benefits and that it lowers social costs. Also enhanced consumer comfort is a result of distribution of water with low scaling potential. This paper will describe the water quality improvements and will quantify the benefits realized in practice.

Research paper thumbnail of Taking green anti-fouling strategies in dead-end ultrafiltration to the next level

Chemical Engineering Research & Design, 2009

In this work we will introduce a hierarchical framework that can be used to optimize an ultrafilt... more In this work we will introduce a hierarchical framework that can be used to optimize an ultrafiltration process that is used for the purification of surface water. Within the suggested framework modelling and optimization of chemical cleaning of membranes were performed. This paper will discuss the proposed model, the quantitative criteria that can be used to select a proper cleaning agent and lastly the optimization procedure on the basis of the dynamic model. Systematic optimization showed that two optimal scenarios for cleaning can be formulated, one in which cleaning time is reduced significantly with respect to a conventional cleaning procedure, and a second one where cleaning time and cleaning agent consumption as well are reduced significantly. These reductions show that the ultrafiltration process can be made sustainable and greener, by systematic optimization of the cleaning process.

Research paper thumbnail of Integrated multi-objective membrane systems application of reverse osmosis at the Amsterdam Water Supply

Desalination, 1998

Within the scope of a project funded by AWWARF and USEPA three very promising IMS&amp... more Within the scope of a project funded by AWWARF and USEPA three very promising IMS's were identified for surface water treatment. This paper will cover some highlights of the research carried out by Amsterdam Water Supply (AWS) and Kiwa on the combination of biological activated carbon filtration, slow sand filtration and (ultra low pressure) reverse osmosis. Primary objectives of this

Research paper thumbnail of Bioavailability of heavy metals in terrestrial and aquatic systems: A quantitative approach

Environmental Toxicology and Chemistry, 1999

... the pH and calcium concentration (as a competitor for the same sorption sites as the metal io... more ... the pH and calcium concentration (as a competitor for the same sorption sites as the metal ion) are considered two of the most important factors that affect the distribution ... With the help of these equations, the distribution of the metal over the biotic and abiotic components in ...

Research paper thumbnail of Comparison of NF/RO membrane performance in integrated membrane systems

Desalination, 2000

Within the framework of the project ‘Integrated multi-objective membrane systems for control of m... more Within the framework of the project ‘Integrated multi-objective membrane systems for control of microbials and DBP precursors, funded by AWWARF and USEPA, four integrated membrane systems (IMSs) for surface water treatment were investigated. The identified IMSs are based on pretreatments including slow sand filtration, bank filtration, coagulation-sedimentation-rapid filtration (CSF) and ultrafiltration respectively. The IMSs were tested on three locations in

Research paper thumbnail of Analysis of ion binding on humic substances and the determination of intrinsic affinity distributions

Analytica Chimica Acta, 1990

are characterized by a vanabIe ekctnc potential and by a vanety of bmdmg sites Ieadmg to chenucal... more are characterized by a vanabIe ekctnc potential and by a vanety of bmdmg sites Ieadmg to chenucal heterogeneity Bmdmg of ions to these substances 1s Influenced by both factors A methodology based on acid-base tltratlons at several salt levels IS presented that allows for the assessment of an appropriate electrostatic double-layer model and the mtrmslc proton affuuty dlstnbutlon The double-layer model 1s used for the conversIon of pH to pHs for each data pomt, where Hs 1s the proton concentration m the diffuse Iayer near the bmdmg site. It 1s shown that with an appropnate double-layer model the proton bmdmg curves at different salt levels converge mto one '*master curve" when pIotted as a function of pHs. The mtnnslc proton affmlty dlstnbutlon can then be denved from the "master curve" using the LOGA method. A ngorous analysis of metal bmdmg to hurmc substances is complex and m practice 1s not feasible. Under two different (slmphfymg) assumptions, namely fuIIy coupled and uncoupled bmdmg, It 1s shown how mtnnslc metal ion affuuty dlstnbutlons can be obtamed Mode1 calcutatlons show that apparent metal ion affuuty dlstnbutlons do not resemble the mtnnslc metal Ion affinity dlstnbutlon.

Research paper thumbnail of Quick-Scan: Selection of micro- and ultrafiltration membranes

Desalination, 1998

ABSTRACT

Research paper thumbnail of Heterogeneity analysis for binding data using an adapted smoothing spline technique

Environmental Science & Technology, 1994

Heterogeneity analysis is a helpful tool to select a proper model for the description of ion bind... more Heterogeneity analysis is a helpful tool to select a proper model for the description of ion binding to polyfunctional ligands. Two approaches of heterogeneity analysis are discussed: the local isotherm approximation (LIA) method and the differential equilibrium function (DEF) method. For both methods, the approximate distribution function of a given ligand system is a series of derivatives of the experimentally obtained binding function. To obtain reliable derivatives, a smoothing spline routine is adapted for the present problem. The smoothing parameter of the spline is determined by a generalized cross-validation criterion in combination with physical constraints derived from the binding function. With the thus obtained spline function, the distribution is calculated. Error bars for the obtained distribution function can be calculated using the variance in the spline function. The error bars indicate whether peaks in the distribution are significant. The methodology is applied to a synthetic data set to illustrate its capabilities and limitations and is applied to copper binding to humic materials (data set of Hansen et al.) to illustrate its use in practice. The quality of the calculated distribution function depends on the experimental error in the data, the number of data points, and the binding range. On the basis of the calculated distribution function, a binding model can be selected.

Research paper thumbnail of Analysis of the binding heterogeneity of natural ligands using adsorption data

Cheminform, 1992

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was e... more ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Research paper thumbnail of Integrity of membrane elements, vessels and systems

Research paper thumbnail of Desalination of brackish groundwater: the concentrate dilemma

Desalination, 2005

Vitens uses ground water from deep confined aquifers as one of her drinking water sources. These ... more Vitens uses ground water from deep confined aquifers as one of her drinking water sources. These sources have an excellent raw water quality due to the absence of anthropogenic contaminants. However, the wells are susceptible for upconing of brackish groundwater. As a result several wells had to be abandoned leading to a reduced production capacity. Recently the ‘fresh holder’ concept was introduced by Kiwa Water Research to solve this problem. It is not clear yet if this concept is allowed and if there are any technical problems. In order to investigate both the technical and political implications of the described concept a demonstration project is set up near the city of Deventer. The first step is to see whether the required permits can be obtained. Since this is a new application, the discussion with the authorities will be started in an early stage.

Research paper thumbnail of Feasibility of micro- and ultrafiltration for the direct treatment of surface water: results of various pilot studies

Research paper thumbnail of Twenty years of experience with central softening in The Netherlands: Water quality - Environmental benefits - Costs

Central softening has been utilized by the Dutch water utilities since the late 1970s. It was int... more Central softening has been utilized by the Dutch water utilities since the late 1970s. It was introduced in the water treatment process as a method to supply water with an optimum water composition to prevent lead and copper release and to prevent excessive scaling. Twenty years of experience show that central softening is beneficial for public health, has significant environmental benefits and that it lowers social costs. Also enhanced consumer comfort is a result of distribution of water with low scaling potential. This paper will describe the water quality improvements and will quantify the benefits realized in practice.

Research paper thumbnail of Taking green anti-fouling strategies in dead-end ultrafiltration to the next level

Chemical Engineering Research & Design, 2009

In this work we will introduce a hierarchical framework that can be used to optimize an ultrafilt... more In this work we will introduce a hierarchical framework that can be used to optimize an ultrafiltration process that is used for the purification of surface water. Within the suggested framework modelling and optimization of chemical cleaning of membranes were performed. This paper will discuss the proposed model, the quantitative criteria that can be used to select a proper cleaning agent and lastly the optimization procedure on the basis of the dynamic model. Systematic optimization showed that two optimal scenarios for cleaning can be formulated, one in which cleaning time is reduced significantly with respect to a conventional cleaning procedure, and a second one where cleaning time and cleaning agent consumption as well are reduced significantly. These reductions show that the ultrafiltration process can be made sustainable and greener, by systematic optimization of the cleaning process.