Publications by authors named "Luuk Rietveld"

29 Publications

  • Page 1 of 1

State-of-the-Art Ceramic Membranes for Oily Wastewater Treatment: Modification and Application.

Membranes (Basel) 2021 Nov 19;11(11). Epub 2021 Nov 19.

Sanitary Engineering, Department of Water Management, Faculty of Civil Engineering and Geosciences, Delft University of Technology, Stevinweg 1, 2628 CN Delft, The Netherlands.

Membrane filtration is considered to be one of the most promising methods for oily wastewater treatment. Because of their hydrophilic surface, ceramic membranes show less fouling compared with their polymeric counterparts. Membrane fouling, however, is an inevitable phenomenon in the filtration process, leading to higher energy consumption and a shorter lifetime of the membrane. It is therefore important to improve the fouling resistance of the ceramic membranes in oily wastewater treatment. In this review, we first focus on the various methods used for ceramic membrane modification, aiming for application in oily wastewater. Then, the performance of the modified ceramic membranes is discussed and compared. We found that, besides the traditional sol-gel and dip-coating methods, atomic layer deposition is promising for ceramic membrane modification in terms of the control of layer thickness, and pore size tuning. Enhanced surface hydrophilicity and surface charge are two of the most used strategies to improve the performance of ceramic membranes for oily wastewater treatment. Nano-sized metal oxides such as TiO, ZrO and FeO and graphene oxide are considered to be the potential candidates for ceramic membrane modification for flux enhancement and fouling alleviation. The passive antifouling ceramic membranes, e.g., photocatalytic and electrified ceramic membranes, have shown some potential in fouling control, oil rejection and flux enhancement, but have their limitations.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/membranes11110888DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8625480PMC
November 2021

Financial, institutional, environmental, technical, and social (FIETS) aspects of water, sanitation, and hygiene conditions in indigenous - rural Indonesia.

BMC Public Health 2021 09 22;21(1):1723. Epub 2021 Sep 22.

Department of Water Management, Faculty of Civil Engineering and Geosciences, Delft University of Technology, Delft, the Netherlands.

Background: There is increasing recognition of the complexity underlying WASH conditions in developing countries. This article explores the complexity by assessing the vulnerability of a specific area to poor WASH conditions using a qualitative approach.

Methods: We present our findings for the district of East Sumba in Indonesia. This area is known as one of the poorest regions in Indonesia with inadequate WASH services, indigenous belief that hinder the practice of WASH-related behaviours, and has a high rate of children malnutrition. All the factors that contribute to poor WASH conditions were discussed through the lens of the Financial, Institutional, Environmental, Technological, and Social (FIETS) framework. We then summarised the factors and visualized the "system" using a mind map which shows how factors are interconnected and helps to find the root causes of poor WASH conditions.

Results: There are three main challenges that inhibit the improvement of WASH conditions in this area: inadequate institutional capacity, water scarcity, and poor socio-economic conditions. We found that a village leader is the most important actor who influences the sustainability of WASH services in this area and healthcare workers are influential WASH promoters. This study also shows how culture shapes people's daily lives and institution performance, and influences the current WASH conditions in East Sumba. The mind map shows there is an overlap and interconnection between FIEST aspects and WASH conditions in the study area.

Conclusion: WASH conditions are influenced by many factors and are often interconnected with each other. Understanding this complexity is necessary to improve WASH conditions and sustain adequate WASH services in developing countries. Finally, WASH interventions have to be considerate of the prevailing cultural practices and should involve multidisciplinary stakeholders.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1186/s12889-021-11800-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8459497PMC
September 2021

How properties of low molecular weight model competitors impact organic micropollutant adsorption onto activated carbon at realistically asymmetric concentrations.

Water Res 2021 Sep 18;202:117443. Epub 2021 Jul 18.

Department of Water Management, Delft University of Technology, PO Box 5048, 2600 GA, Delft, the Netherland; Chair of Water Quality Control, Technische Universität Berlin, KF4, Str. des 17. Juni 135, Berlin 10623, Germany; Berliner Wasserbetriebe, Motardstr. 35, Berlin 13629, Germany.

Low molecular weight (LMW) dissolved organic matter (DOM) is the predominant competitor for adsorption sites against organic micropollutants (OMPs) in activated carbon adsorption. However, top-down approaches using highly complex mixtures of real water DOM do not allow to concisely examine the impacts of specific LMW DOM molecular properties on competitive adsorption. Therefore, we followed a bottom-up approach using fifteen model compounds (mDOM) to elucidate how important DOM characteristics, including hydrophobicity and unsaturated structures (ring, double/triple bond), impact competitiveness. Large concentration asymmetry (~500 μg DOC/μg OMP) made mDOM compounds, which were overall less preferentially adsorbed than OMPs, become competitive against OMPs and inhibit OMP adsorption kinetics by pre-occupation of adsorption sites. Our results revealed that both hydrophobicity interactions and π-interactions increased mDOM competitiveness, while π-interactions outweighed hydrophobic interactions. However, π-interactions could not be satisfactorily evaluated with a parameter such as specific ultraviolet absorbance (SUVA) due to interferences of carboxyl groups in aromatic mDOMs. Instead, mDOM adsorbability, described by mDOM adsorption capacity, proved to be a comprehensive indicator for mDOM competitiveness. To our knowledge, this is the first study that systematically clarifies the impacts of intricately interacting molecular properties on DOM adsorption and the related competition against OMP adsorption. DOM adsorbability may inspire a new fractionation, and assist the further isolation, identification and detailed characterization of LMW DOM competitors in real DOM-containing waters.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.watres.2021.117443DOI Listing
September 2021

Anoxic storage to promote arsenic removal with groundwater-native iron.

Water Res 2021 Sep 5;202:117404. Epub 2021 Jul 5.

Sanitary Engineering Section, Water Management Department, Delft University of Technology, the Netherlands.

Storage containers are usually used to provide a constant water head in decentralized, community groundwater treatment systems for the removal of iron (Fe) and arsenic (As). However, the commonly practiced aeration prior to storage assists in rapid and complete Fe oxidation, resulting in poor As removal, despite sufficient native-Fe in the source water. In this study, it was found that application of anoxic storage enhanced As removal from groundwater, containing ≥300 µg/L of As(III) and 2.33 mg/L of Fe in an As affected village of Rajshahi district in Bangladesh. Although the oxidation of Fe and As(III) during oxic storage was considerably faster, the As/Fe removal ratio was higher during anoxic storage (61-80±5 µgAs/mgFe) compared to the oxic storage (45±5 µgAs/mgFe). This higher As removal efficacy in anoxic storage containers could not be attributed to the speciation of As, since As(V) concentrations were higher during oxic storage due to more favorable abiotic (As(III) oxidation by O and Fenton-like intermediates) and biotic (As(III) oxidizing bacteria, e.g., Sideroxydans, Gallionella, Hydrogenophaga) conditions. The continuous, in-situ hydrous ferric oxide floc formation during flow-through operation, and the favorable lower pH aiding higher sorption capacities for the gradually formed As(V) likely contributed to the improved performance in the anoxic storage containers.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.watres.2021.117404DOI Listing
September 2021

Comparative study of low-cost fluoride removal by layered double hydroxides, geopolymers, softening pellets and struvite.

Environ Technol 2021 Jun 30:1-9. Epub 2021 Jun 30.

Faculty of Civil Engineering and Geosciences, Department of Water Management, Delft University of Technology Delft, The Netherlands.

Excessive F in drinking water due to natural and anthropogenic activities is a serious health hazard affecting humans worldwide. In this study, a comparative assessment was made of eight mineral-based materials with advantageous structural properties for F uptake: layered-double-hydroxides (LDHs), geopolymers, softening pellets and struvite. These materials are considered low-cost, for being either a waste or by-product, or can be locally-sourced. It can be concluded that Ca-based materials showed the strongest affinity for F (Ca-Al-CO LDHs, slag-based geopolymer, softening pellets). The Langmuir adsorption capacity of Ca-Al-CO LDHs, slag-based geopolymer and softening pellets was observed to be 20.83, 5.23 and 1.20 mg/g, respectively. The main mechanism of F uptake on Ca-Al-CO LDHs, Mg-Al-Cl LDHs, slag-based geopolymers and softening pellets was found to be sorption at low initial F concentrations (<10 mg/L) whereas precipitation as CaF is proposed to play a major role at higher initial F concentrations (>20 mg/L). Although the softening pellets had the highest Ca-content (96-97%; XRF), their dense structure and consequent low BET surface area (2-3 m/g), resulted in poorer performance than the Ca-based LDHs and slag-based geopolymers. Nevertheless, geopolymers, as well as struvite, were not considered to be of interest for application in water treatment, as they would need modification due to their poor stability and/or F leaching
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1080/09593330.2021.1946600DOI Listing
June 2021

Arsenic removal from iron-containing groundwater by delayed aeration in dual-media sand filters.

J Hazard Mater 2021 06 11;411:124823. Epub 2020 Dec 11.

Sanitary Engineering Section, Department of Water Management, Delft University of Technology, The Netherlands.

Generally, abstracted groundwater is aerated, leading to iron (Fe) oxidation to Fe and precipitation as Fe-(hydr)oxide (HFO) flocs. This practice of passive groundwater treatment, however, is not considered a barrier for arsenic (As), as removal efficiencies vary widely (15-95%), depending on Fe/As ratio. This study hypothesizes that full utilization of the adsorption capacity of groundwater native-Fe based HFO flocs is hampered by rapid Fe oxidation-precipitation during aeration before or after storage. Therefore, delaying Fe oxidation by the introduction of an anoxic storage step before aeration-filtration was investigated for As(III) oxidation and removal in Rajshahi (Bangladesh) with natural groundwater containing 329(±0.05) µgAs/L. The results indicated that As(III) oxidation in the oxic storage was higher with complete and rapid Fe oxidation (2±0.01 mg/L) than in the anoxic storage system, where Fe oxidation was partial (1.03±0.32 mg/L), but the oxidized As(V)/Fe removal ratio was comparatively higher for the anoxic storage system. The low pH (6.9) and dissolved oxygen (DO) concentration (0.24 mg/L) in the anoxic storage limited the rapid oxidation of Fe and facilitated more As(V) removal. The groundwater native-Fe (2.33±0.03 mg/L) removed 61% of As in the oxic system (storage-aeration-filtration), whereas 92% As removal was achieved in the anoxic system.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jhazmat.2020.124823DOI Listing
June 2021

A Bayesian Belief Network model to link sanitary inspection data to drinking water quality in a medium resource setting in rural Indonesia.

Sci Rep 2020 11 2;10(1):18867. Epub 2020 Nov 2.

Department of Water Management, Delft University of Technology, Delft, The Netherlands.

Assessing water quality and identifying the potential source of contamination, by Sanitary inspections (SI), are essential to improve household drinking water quality. However, no study link the water quality at a point of use (POU), household level or point of collection (POC), and associated SI data in a medium resource setting using a Bayesian Belief Network (BBN) model. We collected water samples and applied an adapted SI at 328 POU and 265 related POC from a rural area in East Sumba, Indonesia. Fecal contamination was detected in 24.4 and 17.7% of 1 ml POC and POU samples, respectively. The BBN model showed that the effect of holistic-combined interventions to improve the water quality were larger compared to individual intervention. The water quality at the POU was strongly related to the water quality at the POC and the effect of household water treatment to improve the water quality was more prominent in the context of better sanitation and hygiene conditions. In addition, it was concluded that the inclusion of extra "external" variable (fullness level of water at storage), besides the standard SI variables, could improve the model's performance in predicting the water quality at POU. Finally, the BBN approach proved to be able to illustrate the interdependencies between variables and to simulate the effect of the individual and combination of variables on the water quality.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41598-020-75827-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7606607PMC
November 2020

Integrating biological As(III) oxidation with Fe(0) electrocoagulation for arsenic removal from groundwater.

Water Res 2021 Jan 17;188:116531. Epub 2020 Oct 17.

Water Management Department, Faculty of Civil engineering and Geosciences, Delft University of Technology, Stevinweg 1, 2628CN Delft, The Netherlands.

Arsenic (As) is a toxic element present in many (ground)water sources in the world. Most conventional As removal techniques require pre-oxidation of the neutral arsenite (As(III)) species to the negatively charged arsenate (As(V)) oxyanion to optimize As removal and minimize chemical use. In this work, a novel, continuous-flow As removal system was developed that combines biological As(III) oxidation by bacteria with Fe electrocoagulation (EC), an Fe(0)-based electrochemical technology that generates reactive Fe(III) precipitates to bind As. The bio-integrated FeEC system (bio-FeEC) showed effective oxidation and removal of 150 µg/L As(III), without the need of chemicals. To remove As to below the WHO guideline of 10 µg/L, 10 times lower charge dosage was required for the bio-FeEC system compared to conventional FeEC. This lower Fe dosage requirement reduced sludge production and energy consumption. The As(III) oxidizing biomass was found to consist of bacteria belonging to Comamonadaceae, Rhodobacteraceae and Acidovorax, which are capable of oxidizing As(III) and are common in drinking water biofilms. Characterization of the As-laden Fe solids by X-ray absorption spectroscopy indicated that both bio-FeEC and conventional FeEC produced solids consistent with a mixture of lepidocrocite and 2-line ferrihydrite. Arsenic bound to the solids was dominantly As(V), but a slightly higher fraction of As(V) was detected in the bio-FeEC solids compared to the conventional FeEC.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.watres.2020.116531DOI Listing
January 2021

Simultaneous removal of ammonium ions and sulfamethoxazole by ozone regenerated high silica zeolites.

Water Res 2021 Jan 29;188:116472. Epub 2020 Sep 29.

Department of Water Management, Faculty of Civil Engineering and Geosciences, Delft University of Technology, P.O. Box 5048, 2600 GA Delft, the Netherlands.

Continuous development of industry and civilization has led to changes in composition, texture and toxicity of waste water due to the wide range of pollutants being present. Considering that the conventional wastewater treatment methods are insufficient for removing micropollutants and nutrients to a high level, other, alternative, treatment methods should be used to polish wastewater treatment plant effluents. In this study we developed an alternative, polishing concept for removal of ammonium and micropollutants that could potentially be incorporated in existing wastewater treatment plants. We demonstrated a method to use high silica MOR zeolite granules as an adsorbent for simultaneous removal of the micropollutant sulfamethoxazole (SMX) and ammonium (NH) ions from aqueous solutions. At an initial NH concentration of 10 mg/L the high silica zeolite mordenite (MOR) granules removed 0.42 mg/g of NH, similar to the removal obtained by commonly used natural zeolite Zeolita (0.44 mg/g). However, at higher NH concentrations the Zeolita performed better. In addition, the Langmuir isotherm model showed a higher maximum adsorption capacity of Zeolita (q, 4.08 mg/g), which was about two times higher than that of MOR (2.11). The adsorption capacity of MOR towards SMX, at both low (2 µg/L) and high (50 mg/L) initial concentrations, was high and even increased in the presence of NH ions. The used adsorbent could be regenerated with ozone and reused in consecutive adsorption-regeneration cycles with marginal decrease in the total adsorption capacity.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.watres.2020.116472DOI Listing
January 2021

Projecting competition between 2-methylisoborneol and natural organic matter in adsorption onto activated carbon from ozonated source waters.

Water Res 2020 Apr 4;173:115574. Epub 2020 Feb 4.

Delft University of Technology, Department of Water Management, PO Box 5048, 2600GA, Delft, the Netherlands.

Though the ozone-activated carbon process has been widely applied for drinking water purification, little is known about how ozone-modified natural organic matter (NOM) competes with micropollutants in activated carbon adsorption. In this study, three natural waters and one synthetic water (standard humics solution) with highly heterogeneous NOM compositions were employed to investigate the interference of ozonated NOM with the adsorption of 2-methylisoborneol (MIB). Analysis using liquid chromatography with online carbon and UV detection (LC-OCD-UVD) revealed that ozonation led to various disintegration patterns of macromolecules in NOM, and UV absorbance was reduced markedly for nearly all NOM fractions. Powdered activated carbon (PAC) adsorption experiments showed that increasing ozone consumption coincided with reducing NOM competition against MIB in the three natural waters, as expressed by the fitted initial concentrations of the equivalent background compound (c). In the synthetic water, in contrast, competition increased under low/moderate specific ozone consumptions and then decreased with further elevation of ozone consumptions. Regarding the significance on affecting ozonated NOM interference, aromaticity reduction outweighed formation of low molecular weight (LMW) organics in most cases, enhancing MIB adsorption capacity. However, disintegration of the humics fraction with larger molecular weight (1,103 g/mol, as compared to 546-697 g/mol in three natural waters) into smaller, more competitive fractions caused the observed initial deteriorated MIB adsorption in synthetic water. A superior correlation between c and the UV absorbance of LMW organics (R = 0.93) over concentrations of LMW organics underlined the importance of the aromatic properties in competitive adsorption projection for ozone pretreated natural waters. Furthermore, the change of relative concentration of UV absorbing compounds during ozonation could help estimate the decrease of c, which could be a promising tool for waterworks to adjust PAC doses for MIB removal in ozonated waters.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.watres.2020.115574DOI Listing
April 2020

Fluoride removal by Ca-Al-CO layered double hydroxides at environmentally-relevant concentrations.

Chemosphere 2020 Mar 6;243:125307. Epub 2019 Nov 6.

Faculty of Civil Engineering and Geosciences, Department of Sanitary Engineering, Delft University of Technology, P.O. Box 5048, 2600 GA, Delft, the Netherlands.

In this study, F removal by Ca-Al-CO layered double hydroxides (LDHs) was investigated at environmentally-relevant concentration ranges (2-12 mg/L) to below the WHO guideline, with an emphasis on the effect of LDHs' modification, as well as the effects of initial F concentration, adsorbent dose, pH, temperature and co-existing ions. Ca-Al-CO LDHs, either untreated, calcined or microwave treated, showed affinity for the removal of F from synthetic groundwater with capacities of 6.7-8.4 mg F/g LDHs at groundwater-relevant pH, with a higher F removal capacity at lower pH (<8) and lower temperature (12 °C, as compared to 25 °C & 35 °C). Since calcination and microwave treatment resulted in only marginal defluorination improvements, using untreated LDHs appears the practically most feasible option. For the untreated LDHs, competition with Cl and NO was not observed, whereas at higher HCO and SO concentrations (>250 mg/L) a slight reduction in F removal was observed. This study indicates the potential of Ca-Al-CO LDHs as a cost-effective F removal technology, particularly when locally sourced and in combination with low-cost pH correction.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.chemosphere.2019.125307DOI Listing
March 2020

Natural organic matter-cations complexation and its impact on water treatment: A critical review.

Water Res 2019 Sep 21;160:130-147. Epub 2019 May 21.

Univ. Lille CNRS, UMR 8516 - LASIR, Equipe Physico-Chimie de L'Environnement, F-59000, Lille, France. Electronic address:

The quality and quantity of natural organic matter (NOM) has been observed to evolve which poses challenges to water treatment facilities. Even though NOM may not be toxic itself, its presence in water has aesthetic effects, enhances biological growth in distribution networks, binds with pollutants and controls the bioavailability of trace metals. Even though NOM has heterogeneous functional groups, the predominant ones are the carboxyl and the phenolic groups, which have high affinities for metals depending on the pH. The properties of both the NOM and the trace elements influence the binding kinetics and preferences. Ca prefers to bind with the carboxylic groups especially at a low pH while Zn prefers the amine groups though practically, most cations bind to several functions groups. The nature of the chemical environment (neighboring ligands) the ligand finds itself equally influences its preference for a cation. The presence of NOM, cations or a complex of NOM-cations may have significant impact on the efficiency of water processes such as coagulation, adsorption, ion exchange resin and membrane filtration. In coagulation, the complexation between the coagulant salts and NOM helps to remove NOM from solution. This positive influence can further be enhanced by the addition of Ca. A negative influence is however, observed in lime-softening method as NOM complexes with Ca. A negative influence is also seen in membrane filtration where divalent cations partially neutralize the carboxyl functional groups of NOM thereby reducing the repulsion effect on NOM and increasing membrane fouling. The formation of disinfection by-products could either be increased or reduced during chlorination, the speciation of products formed is modified with generally the enhancement of haloacetic acid formation observed in presence of metal cations. This current work, presents in details the interactions of cations and NOM in the environment, the preference of cations for each functional group and the possible competition between cations for binding sites, as well as the possible impacts of the presence of cations, NOM, or their complex on water treatment processes.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.watres.2019.05.064DOI Listing
September 2019

Understanding the effect of socio-economic characteristics and psychosocial factors on household water treatment practices in rural Nepal using Bayesian Belief Networks.

Int J Hyg Environ Health 2019 06 29;222(5):847-855. Epub 2019 Apr 29.

Delft University of Technology, Department of Water Management, the Netherlands.

About 20 Million (73%) people in Nepal still do not have access to safely managed drinking water service and 22 million (79%) do not treat their drinking water before consumption. Few studies have addressed the combination of socio-economic characteristics and psychosocial factors that explain such behaviour in a probabilistic manner. In this paper we present a novel approach to assess the usage of household water treatment (HWT), using data from 451 households in mid and far-western rural Nepal. We developed a Bayesian belief network model that integrates socio-economic characteristics and five psychosocial factors. The socio-economic characteristics of households included presence of young children, having been exposed to HWT promotion in the past, level of education, type of water source used, access to technology and wealth level. The five psychosocial factors capture households' perceptions of incidence and severity of water-borne infections, attitudes towards the impact of poor water quality on health, water treatment norms and the knowledge level for performing HWT. We found that the adoption of technology was influenced by the psychosocial factors norms, followed by the knowledge level for operating the technology. Education, wealth level, and being exposed to the promotion of HWT were the most influential socio-economic characteristics. Interestingly, households who were connected to a piped water scheme have a higher probability of HWT adoption compared to other types of water sources. The scenario analysis revealed that interventions that only target single socio-economic characteristics do not effectively boost the probability of HWT practice. However, interventions addressing several socio-economic characteristics increase the probability of HWT adoption among the target groups.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.ijheh.2019.04.005DOI Listing
June 2019

Electrochemical Oxidation of Organic Pollutants Powered by a Silicon-Based Solar Cell.

ACS Omega 2018 Oct 30;3(10):14392-14398. Epub 2018 Oct 30.

Photovoltaic Materials and Devices (PVMD), Electrical Engineering, Mathematics and Computer Science Faculty and Sanitary Engineering, Civil Engineering Faculty, Delft University of Technology, 2628 CD Delft, The Netherlands.

Currently available (photo-)electrochemical technologies for water treatment establish a trade-off between low-pollutant concentration and costs. This paper aims at decoupling these two variables by designing a photo-oxidation device using earth abundant materials and an electronic-free approach. The proposed device combines a graphite/graphite electrochemical system with a silicon-based solar cell that provides the necessary electrical power. First, the optimum operational voltage for the graphite/graphite electrochemical system was found to be around 1.6 V. That corresponded closely to the voltage produced by an a-Si:H/a-Si:H tandem solar cell of approximately 1.35 V. This configuration was shown to provide the best pollutant degradation in relation to the device area, removing 70% of the initial concentration of phenol and 90% of the methylene blue after 4 h of treatment. The chemical oxygen demand (COD) removal of these two contaminants after 4 h of treatment was also promising, 55 and 30%, respectively. Moreover, connecting several solar cells in series led to higher pollutant degradation but lower COD removal, suggesting that the degradation of the intermediate components is a limiting factor. This is expected to be due to the higher currents achieved by the series-connected configuration, which would favor other reactions such as polymerization over the degradation of intermediate species.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acsomega.8b02502DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6369653PMC
October 2018

Natural recovery of infiltration capacity in simulated bank filtration of highly turbid waters.

Water Res 2018 12 8;147:299-310. Epub 2018 Oct 8.

Delft University of Technology, Faculty of Civil Engineering and Geosciences, Stevinweg 1, 2628CN, Delft, Netherlands.

As a consequence of the suspended sediments in river water, cake formation on the streambed and clogging of the aquifer may occur, leading to a decline in the production yield of riverbank filtration systems, particularly in highly turbid river waters. However, naturally occurring flow forces may induce sufficient scouring of the streambed, thereby self-regulating the thickness of the formed cake layer. This study assessed the recovery of the infiltration capacity in a simulated physically clogged riverbank filtration system, due to self-cleansing processes. A straight tilting flume, provided with an infiltration column at the bottom, was used for emulating clogging, infiltration and self-cleansing. Based on the presented research it may be concluded that the infiltration of a mixture of different sediments, as found in natural water bodies, can already be recovered at low shear stresses. Clay and silt behaved very differently, due to the difference in cohesiveness. Clay was found to produce a persistent sticky cake layer, whereas silt penetrated deeper into the bed, both resulting in an absence of infiltration velocity recovery. A cake layer of fine sand sediments was easiest to remove, resulting in dune formation on the streambed. However, due to deep bed clogging by fine sand particles in a coarser streambed, the infiltration velocity did not fully recover. The interaction between mixed suspended sediments (5% clay, 80% silt, and 15% fine sand) resulted in uneven erosion patterns during scouring of the streambed and recovery of the infiltration velocity is low. Altogether it may be concluded that natural recovery of infiltration capacity during river bank filtration of highly turbid waters is expected to occur, as long as the river carries a mixture of suspended sediments and the sand of the streambed is not too coarse.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.watres.2018.10.009DOI Listing
December 2018

High-silica zeolites for adsorption of organic micro-pollutants in water treatment: A review.

Water Res 2018 11 7;144:145-161. Epub 2018 Jul 7.

Department of Water Management, Faculty of Civil Engineering and Geosciences, Delft University of Technology, P.O. Box 5048, 2600, GA Delft, The Netherlands.

High-silica zeolites have been found to be effective adsorbents for the removal of organic micro-pollutants (OMPs) from impaired water, including various pharmaceuticals, personal care products, industrial chemicals, etc. In this review, the properties and fundamentals of high-silica zeolites are summarised. Recent research on mechanisms and efficiencies of OMP adsorption by high-silica zeolites are reviewed to assess the potential opportunities and challenges for the application of high-silica zeolites for OMP adsorption in water treatment. It is concluded that the adsorption capacities are well-related to surface hydrophobicity/hydrophilicity and structural features, e.g. micropore volume and pore size of high-silica zeolites, as well as the properties of OMPs. By using high-silica zeolites, the undesired competitive adsorption of background organic matter (BOM) in natural water could potentially be prevented. In addition, oxidative regeneration could be applied on-site to restore the adsorption capacity of zeolites for OMPs and prevent the toxic residues from re-entering the environment.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.watres.2018.07.017DOI Listing
November 2018

Characterization of the bacterial community in shower water before and after chlorination.

J Water Health 2018 Apr;16(2):233-243

Department of Water Management, Faculty of Civil Engineering and Geosciences, Delft University of Technology, Stevinweg 1, 2628 CN Delft, The Netherlands E-mail:

Bathers release bacteria in swimming pool water, but little is known about the fate of these bacteria and potential risks they might cause. Therefore, shower water was characterized and subjected to chlorination to identify the more chlorine-resistant bacteria that might survive in a chlorinated swimming pool and therefore could form a potential health risk. The total community before and after chlorination (1 mg Cl L for 30 s) was characterized. More than 99% of the bacteria in the shower water were Gram-negative. The dominant bacterial families with a relative abundance of ≥10% of the total (non-chlorinated and chlorinated) communities were Flavobacteriaceae (24-21%), Xanthomonadaceae (23-24%), Moraxellaceae (12-11%) and Pseudomonadaceae (10-22%). The relative abundance of Pseudomonadaceae increased after chlorination and increased even more with longer contact times at 1 mg ClL. Therefore, Pseudomonadaceae were suggested to be relatively more chlorine resistant than the other identified bacteria. To determine which bacteria could survive chlorination causing a potential health risk, the relative abundance of the intact cell community was characterized before and after chlorination. The dominant bacterial families in the intact community (non-chlorinated and chlorinated) were Xanthomonadaceae (21-17%) and Moraxellaceae (48-57%). Moraxellaceae were therefore more chlorine resistant than the other identified intact bacteria present.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.2166/wh.2017.189DOI Listing
April 2018

Integrating powdered activated carbon into wastewater tertiary filter for micro-pollutant removal.

J Environ Manage 2016 Jul 12;177:45-52. Epub 2016 Apr 12.

Department of Water Management, Faculty of Civil Engineering and Geoscience, Delft University of Technology, P.O. Box 5048, 2600, GA, Delft, The Netherlands.

Integrating powdered activated carbon (PAC) into wastewater tertiary treatment is a promising technology to reduce organic micro-pollutant (OMP) discharge into the receiving waters. To take advantage of the existing tertiary filter, PAC was pre-embedded inside the filter bed acting as a fixed-bed adsorber. The pre-embedding (i.e. immobilization) of PAC was realized by direct dosing a PAC solution on the filter top, which was then promoted to penetrate into the filter media by a down-flow of tap water. In order to examine the effectiveness of this PAC pre-embedded filter towards OMP removal, batch adsorption tests, representing PAC contact reactor (with the same PAC mass-to-treated water volume ratio as in the PAC pre-embedded filter) were performed as references. Moreover, as a conventional dosing option, PAC was dosed continuously with the filter influent (i.e. the wastewater secondary effluent with the investigated OMPs). Comparative results confirmed a higher OMP removal efficiency associated with the PAC pre-embedded filter, as compared to the batch system with a practical PAC residence time. Furthermore, over a filtration period of 10 h (approximating a realistic filtration cycle for tertiary filters), the continuous dosing approach resulted in less OMP removal. Therefore, it was concluded that the pre-embedding approach can be preferentially considered when integrating PAC into the wastewater tertiary treatment for OMP elimination.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jenvman.2016.04.003DOI Listing
July 2016

Influence of activated carbon preloading by EfOM fractions from treated wastewater on adsorption of pharmaceutically active compounds.

Chemosphere 2016 May 15;150:49-56. Epub 2016 Feb 15.

Faculty of Civil Engineering and Geoscience, Delft University of Technology, P.O. Box 5048, 2600GA Delft, The Netherlands.

In this study, the preloading effects of different fractions of wastewater effluent organic matter (EfOM) on the adsorption of trace-level pharmaceutically active compounds (PhACs) onto granular activated carbon (GAC) were investigated. A nanofiltration (NF) membrane was employed to separate the EfOM by size, and two GACs with distinct pore structures were chosen for comparison. The results showed that preloading with EfOM substantially decreased PhAC uptake of the GACs; however, comparable PhAC adsorption capacities were achieved on GACs preloaded by feed EfOM and the NF-permeating EfOM. This indicates that: (1) the NF-rejected, larger EfOM molecules with an expectation to block the PhAC adsorption pores exerted little impact on the adsorbability of PhACs; (2) the smaller EfOM molecules present in the NF permeate contributed mainly to the decrease in PhAC uptake, mostly due to site competition. Of the two examined GACs, the wide pore-size-distributed GAC was found to be more susceptible to EfOM preloading than the microporous GAC. Furthermore, among the fourteen investigated PhACs, the negatively charged hydrophilic PhACs were generally subjected to a greater EfOM preloading impact.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.chemosphere.2016.01.121DOI Listing
May 2016

Reuse of spent granular activated carbon for organic micro-pollutant removal from treated wastewater.

J Environ Manage 2015 Sep 18;160:98-104. Epub 2015 Jun 18.

Faculty of Civil Engineering and Geoscience, Delft University of Technology, P.O. Box 5048, 2600GA, Delft, The Netherlands.

Spent granular activated carbons (sGACs) for drinking water treatments were reused via pulverizing as low-cost adsorbents for micro-pollutant adsorption from a secondary treated wastewater effluent. The changes of physicochemical characteristics of the spent carbons in relation to the fresh carbons were determined and were correlated to the molecular properties of the respective GAC influents (i.e. a surface water and a groundwater). Pore size distribution analysis showed that the carbon pore volume decreased over a wider size range due to preloading by surface water, which contains a broader molecular weight distribution of organic matter in contrast to the groundwater. However, there was still considerable capacity available on the pulverized sGACs for atrazine adsorption in demineralized water and secondary effluent, and this was particularly the case for the groundwater spent GAC. However, as compared to the fresh counterparts, the decreased surface area and the induced surface acidic groups on the pulverized sGACs contributed both to the lower uptake and the more impeded adsorption kinetic of atrazine in the demineralized water. Nonetheless, the pulverized sGACs, especially the one preloaded by surface water, was less susceptible to adsorption competition in the secondary effluent, due to its negatively charged surface which can repulse the accessibility of the co-present organic matter. This suggests the reusability of the drinking water spent GACs for micro-pollutant adsorption in the treated wastewater.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jenvman.2015.06.011DOI Listing
September 2015

EDTA: a synthetic draw solute for forward osmosis.

Water Sci Technol 2014 ;70(10):1677-82

KWR Watercycle Research Institute, Post box 1072, 3430 BB Nieuwegein, The Netherlands.

The draw solution is the driving force of the forward osmosis (FO) process; however, the solute loss of the draw solute to the feed side is a general, financial limitation for most applications. The anthropogenic amino acid ethylenediaminetetraacetic acid (EDTA) was investigated as a draw solution for FO. At concentrations of approximately 1.0 osmol/kg, EDTA demonstrated comparable water fluxes (Jv = 5.29 L/m(2) h) to the commonly used salt, NaCl (Jv = 4.86 L/m(2) h), and both produced better water fluxes than glucose (Jv = 3.46 L/m(2) h). EDTA showed the lowest solute loss with Js (reverse solute loss or solute leakage) = 0.54 g/m(2) h. The molecular weight, degree of ionisation and charge of EDTA played a major role in this efficiency and EDTA was therefore well rejected by the membrane, showing a low Js/Jv ratio of 0.10 g/L. Owing to the low solute loss of EDTA and its resistance to biodegradation, this compound has the potential to be used as a draw solute for FO during long periods without requiring much replenishment.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.2166/wst.2014.424DOI Listing
May 2015

Comparison of the effects of extracellular and intracellular organic matter extracted from Microcystis aeruginosa on ultrafiltration membrane fouling: dynamics and mechanisms.

Environ Sci Technol 2014 Dec 26;48(24):14549-57. Epub 2014 Nov 26.

State Key Laboratory of Pollution Control and Resource Reuse, Tongji University , Shanghai 200092, China.

Algae organic matter (AOM), including intracellular organic matter (IOM) and extracellular organic matter (EOM), are major membrane foulants in the treatment of algae-polluted water. In this study, the effects of EOM and IOM (at dissolved organic concentrations of 8 mg/L) on the fouling of a poly(ether sulfone) ultrafiltration (UF) membrane were investigated using a dead-end down-flow UF unit. Changes in the membrane pore geometry and the interaction energy between the membrane and foulants were analyzed based on the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory. The data (relative standard deviation within 10%) showed that UF was able to retain 57% and 46% of IOM and EOM respectively, while the corresponding membrane fluxes rapidly reduced to 28% and 33% of their respective initial values after a specific filtration volume of only 3.75 mL/cm(2). The fouling model implied that cake formation was the major mechanism. Specifically, IOM foulant had a much greater free energy of cohesion (-59.08 mJ/m(2)) than EOM foulant (3.2 mJ/m(2)), leading to the formation of a compacted cake layer on the membrane surface. In contrast, small molecules of hydrophobic EOM tended to be adsorbed into the membrane pores, leading to significant reduction of the pore size and membrane flux. Therefore, the overall fouling rates caused by EOM and IOM were comparable when both of the above-mentioned mechanisms were considered.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/es5035365DOI Listing
December 2014

A bottom-up approach to estimate dry weather flow in minor sewer networks.

Water Sci Technol 2014 ;69(5):1059-66

Department of Water Management, Delft University of Technology, Stevinweg 1, 2628 CN Delft, The Netherlands E-mail:

In order to evaluate the feasibility of installing decentralised installations for wastewater reuse in cities, information about flows at specific spots of a sewer is needed. However, measuring intermittent flows in partially filled conduits is a technical task which is sometimes difficult to accomplish. This paper describes a method to model intermittent discharges in small sewers by linking a stochastic model for wastewater discharge to a hydraulic model to predict the attenuation of the discharges and its impact on the arrival time to a defined spot. The method was validated in a case study. The model estimated adequately the wastewater discharges on working days.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.2166/wst.2014.010DOI Listing
May 2014

Effect of PAC dosage in a pilot-scale PAC-MBR treating micro-polluted surface water.

Bioresour Technol 2014 Feb 22;154:290-6. Epub 2013 Dec 22.

Delft University of Technology, P. O. Box 5048, 2600 GA Delft, The Netherlands.

To address the water scarcity issue and advance the traditional drinking water treatment technique, a powdered activated carbon-amended membrane bioreactor (PAC-MBR) is proposed for micro-polluted surface water treatment. A pilot-scale study was carried out by initially dosing different amounts of PAC into the MBR. Comparative results showed that 2g/L performed the best among 0, 1, 2 and 3g/L PAC-MBR regarding organic matter and ammonia removal as well as membrane flux sustainability. 1g/L PAC-MBR exhibited a marginal improvement in pollutant removal compared to the non-PAC system. The accumulation of organic matter in the bulk mixture of 3g/L PAC-MBR led to poorer organic removal and severer membrane fouling. Molecular weight distribution of the bulk liquid in 2g/L PAC-MBR revealed the synergistic effects of PAC adsorption/biodegradation and membrane rejection on organic matter removal. Additionally, a lower amount of soluble extracellular polymer substances in the bulk can be secured in 21 days operation.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.biortech.2013.12.075DOI Listing
February 2014

Tight ceramic UF membrane as RO pre-treatment: the role of electrostatic interactions on phosphate rejection.

Water Res 2014 Jan 14;48:498-507. Epub 2013 Oct 14.

Department of Sanitary Engineering, Faculty of Civil Engineering and Geosciences, Delft University of Technology, P.O. Box 5048, 2600 GA Delft, The Netherlands. Electronic address:

Phosphate limitation has been reported as an effective approach to inhibit biofouling in reverse osmosis (RO) systems for water purification. The rejection of dissolved phosphate by negatively charged TiO2 tight ultrafiltration (UF) membranes (1 kDa and 3 kDa) was observed. These membranes can potentially be adopted as an effective process for RO pre-treatment in order to constrain biofouling by phosphate limitation. This paper focuses on electrostatic interactions during tight UF filtration. Despite the larger pore size, the 3 kDa ceramic membrane exhibited greater phosphate rejection than the 1 kDa membrane, because the 3 kDa membrane has a greater negative surface charge and thus greater electrostatic repulsion against phosphate. The increase of pH from 6 to 8.5 led to a substantial increase in phosphate rejection by both membranes due to increased electrostatic repulsion. At pH 8.5, the maximum phosphate rejections achieved by the 1 kDa and 3 kDa membrane were 75% and 86%, respectively. A Debye ratio (ratio of the Debye length to the pore radius) is introduced in order to evaluate double layer overlapping in tight UF membranes. Threshold Debye ratios were determined as 2 and 1 for the 1 kDa and 3 kDa membranes, respectively. A Debye ratio below the threshold Debye ratio leads to dramatically decreased phosphate rejection by tight UF membranes. The phosphate rejection by the tight UF, in combination with chemical phosphate removal by coagulation, might accomplish phosphate-limited conditions for biological growth and thus prevent biofouling in the RO systems.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.watres.2013.10.008DOI Listing
January 2014

Flow cytometry and adenosine tri-phosphate analysis: alternative possibilities to evaluate major bacteriological changes in drinking water treatment and distribution systems.

Water Res 2012 Oct 20;46(15):4665-76. Epub 2012 Jun 20.

Eawag, Swiss Federal Institute of Aquatic Science and Technology, Ueberlandstrasse 133, 8600 Dübendorf, Switzerland.

An ever-growing need exists for rapid, quantitative and meaningful methods to quantify and characterize the effect of different treatment steps on the microbiological processes and events that occur during drinking water treatment and distribution. Here we compared cultivation-independent flow cytometry (FCM) and adenosine tri-phosphate (ATP) analysis with conventional cultivation-based microbiological methods, on water samples from two full-scale treatment and distribution systems. The two systems consist of nearly identical treatment trains, but their raw water quality and pre-treatment differed significantly. All of the drinking water treatment processes affected the microbiological content of the water considerably, but once treated, the finished water remained remarkably stable throughout the distribution system. Both the FCM and ATP data were able to describe the microbiology of the systems accurately, providing meaningful process data when combined with other parameters such as dissolved organic carbon analysis. Importantly, the results highlighted a complimentary value of the two independent methods: while similar trends were mostly observed, variations in ATP-per-cell values between water samples were adequately explained by differences in the FCM fingerprints of the samples. This work demonstrates the value of alternative microbial methods for process/system control, optimization and routine monitoring of the general microbial quality of water during treatment and distribution.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.watres.2012.06.010DOI Listing
October 2012

Water recovery from sewage using forward osmosis.

Water Sci Technol 2011 ;64(7):1443-9

KWR Watercycle Research Institute, The Netherlands.

This research is part of the Sewer Mining project aimed at developing a new technological concept by extracting water from sewage by means of forward osmosis (FO). FO, in combination with a reconcentration system, e.g. reverse osmosis (RO) is used to recover high-quality water. Furthermore, the subsequent concentrated sewage (containing an inherent energy content) can be converted into a renewable energy (RE) source (i.e. biogas). The effectiveness of FO membranes in the recovery of water from sewage has been evaluated. Stable FO water flux values (>4.3 LMH) were obtained with primary effluent (screened, not treated) used as the feed solution. Fouling of the membrane was also induced and further investigated. Accumulated fouling was found to be apparent, but not irreversible. Sewer Mining could lead to a more economical and sustainable treatment of wastewater, facilitating the extraction of water and energy from sewage and changing the way it is perceived: not as waste, but as a resource.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.2166/wst.2011.773DOI Listing
April 2012

Influence of natural organic matter on the screening of pharmaceuticals in water by using liquid chromatography with full scan mass spectrometry.

Anal Chim Acta 2011 Aug 14;700(1-2):114-25. Epub 2011 Jan 14.

Department of Sanitary Engineering, Faculty of Civil Engineering and Geosciences, Delft University of Technology, Delft, The Netherlands.

The influence of natural organic matter on the screening of pharmaceuticals in water was determined by using high resolution liquid chromatography (HRLC) combined with full scan mass spectrometry (MS) techniques like time of flight (ToF) or Orbitrap MS. Water samples containing different amount of natural organic matter (NOM) and residues of a set of 11 pharmaceuticals were analyzed by using Exactive Orbitrap™ LC-MS. The samples were screened for residues of pharmaceuticals belonging to different classes like benzimidazoles, macrolides, penicillins, quinolones, sulfonamides, tetracyclines, tranquillizers, non-steroidal anti-inflammatory drugs (NSAIDs), anti-epileptics and lipid regulators. The method characteristics were established over a concentration range of 0.1-500 μg L(-1). The 11 pharmaceuticals were added to two effluent and two influent water samples. The NOM concentration within the samples ranged from 2 to 8 mg L(-1) of dissolved organic carbon. The HRLC-Exactive Orbitrap™ LC-MS system was set at a resolution of 50,000 (FWHM) and this selection was found sufficient for the detection of the list of pharmaceuticals. With this resolution setting, accurate mass measurements with errors below 2 ppm were found, despite of the NOM concentration of the different types of water samples. The linearities were acceptable with correlation coefficients greater than 0.95 for 30 of the 51 measured linearities. The limit of detection varies between 0.1 μg L(-1)and 100 μg L(-1). It was demonstrated that sensitivity could be affected by matrix constituents in both directions of signal reduction or enhancement. Finally it was concluded that with direct shoot method used (no sample pretreatment) all compounds, were detected but LODs depend on matrix-analyte-concentration combination. No direct relation was observed between NOM concentration and method characteristics. For accurate quantification the use of internal standards and/or sample clean-up is necessary. The direct shoot method is only applicable for qualitative screening purposes. The use of full scan MS makes it possible to search for unknown contaminants. With the use of adequate software and a database containing more than 50,000 entries a tool is available to search for unknowns.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.aca.2010.12.040DOI Listing
August 2011

Model-based pH monitor for sensor assessment.

Water Sci Technol 2009 ;60(3):709-15

DHV BV, PO Box 1132, Amersfoort 3800 BC, The Netherlands.

Owing to the nature of the treatment processes, monitoring the processes based on individual online measurements is difficult or even impossible. However, the measurements (online and laboratory) can be combined with a priori process knowledge, using mathematical models, to objectively monitor the treatment processes and measurement devices. The pH measurement is a commonly used measurement at different stages in the drinking water treatment plant, although it is a unreliable instrument, requiring significant maintenance. It is shown that, using a grey-box model, it is possible to assess the measurement devices effectively, even if detailed information of the specific processes is unknown.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.2166/wst.2009.353DOI Listing
September 2009
-->