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Ijpelaar G.F.,KWR Watercycle Research Institute | Ijpelaar G.F.,Royal Haskoning | Harmsen D.J.H.,KWR Watercycle Research Institute | Beerendonk E.F.,KWR Watercycle Research Institute | And 5 more authors.
Ozone: Science and Engineering | Year: 2010

UV/H2O2 advanced oxidation is an effective barrier against organic micro pollutants. Several studies have focused on the degradation of a wide range of pollutants, but regarding the comparison of low-pressure mercury lamps (LP) with medium-pressure mercury lamps (MP) with respect to energy consumption by the UV/H2O2 process, little is known so far. Although the absorbance of H2O2 at 254 nm is low, the results of this research show that the yield of hydroxyl radical formation (OHCT) with LP lamps is comparable or higher than with MP lamps. In a water matrix with a background absorbance due to organics and nitrate, H2O2 absorbs UV light very effectively at 254 nm. Generally, due to the contribution of direct photolysis, the degradation of pollutants is better with MP-UV/H2O2 than with LP-UV/H2O2 at the same UV fluence. Therefore, with LP-UV/H2O2 micro pollutants are predominantly degraded through reaction with OH radicals. However, due to the much higher efficiency of LP lamps in converting electrical energy to UV-C light, the energy required to achieve 90% degradation (EEO) of pesticides and pharmaceuticals can be significantly lower with LP-UV/H2O2 than with MP-UV/H2O2. Results of bench-scale tests show EEO data of the LP-UV/H2O2 process to be 30%-50% lower than for the MP-UV/H2O2 process. At these process conditions MS2 phage inactivation was found to be more than 8 logs for both MP-UV/H2O2 and LP-UV/H2O2. © 2010 International Ozone Association.

Arens B.,Bureau Voor Strand en Duinonderzoek | Geelen L.,Waternet | Van Der Hagen H.,Dunea | Slings R.,NVPWN Waterleidingbedrijf Noord Holland
Landschap | Year: 2012

In this paper we discuss mechanisms for dune mobility and stability, with special reference to the Dutch situation. Currently in the Netherlands, as in other parts of western Europe, dunes are in a phase of stabilization, which results in loss of biodiversity. Dune grasslands, rich in Red List species disappear gradually because of shrub encroachment. Managers are confronted with this process. Stimulating blowouts inside the system seems not enough to enhance durable rejuvenation of the system. Can we restore dune mobility from the beach land inward into the sand dune ecosystem as a solution to maintain biodiversity? Is dune mobility and hence forth increase of the surface of blowouts realistic under the current climatic and environmental changes? We argue that sand supply and an open sea front can be the key factor in the Dutch situation for sustainable rejuvenation.

Van Thienen P.,KWR Watercycle Research Institute | Vries D.,KWR Watercycle Research Institute | Vries D.,Center of Excellence for Sustainable Water Technology | De Graaf B.,Vitens | And 3 more authors.
Procedia Engineering | Year: 2014

In this paper, we investigate the relevance of the stochastic nature of water demand for backtracing of contaminations in drinking water distribution networks. We present an approach to deal with the uncertainty introduced by stochastic demand, which is applied to a full detail part (all pipes) of a hydraulic model of a distribution network in the Netherlands. It is demonstrated that stochastic water demand can introduce significant amounts of uncertainty for backtracing in some parts of tertiary (reticulation) networks in specific, looped configurations. In other parts, the additional uncertainty introduced by stochastic water demand can be limited. © 2013 The Authors. Published by Elsevier Ltd.

Schijven J.F.,National Institute for Public Health and the Environment | Van den Berg H.H.J.L.,National Institute for Public Health and the Environment | Colin M.,Waternet | Dullemont Y.,Waternet | And 3 more authors.
Water Research | Year: 2013

Slow sand filtration (SSF) in drinking water production removes pathogenic microorganisms, but detection limits and variable operational conditions complicate assessment of removal efficiency. Therefore, a model was developed to predict removal of human pathogenic viruses and bacteria as a function of the operational conditions. Pilot plant experiments were conducted, in which bacteriophage MS2 and Escherichia coli WR1 were seeded as model microorganisms for pathogenic viruses and bacteria onto the filters under various temperatures, flow rates, grain sizes and ages of the Schmutzdecke. Removal of MS2 was 0.082-3.3 log10 and that of E. coli WR1 0.94-4.5 log10 by attachment to the sand grains and additionally by processes in the Schmutzdecke. The contribution of the Schmutzdecke to the removal of MS2 and E. coli WR1 increased with its ageing, with sticking efficiency and temperature, decreased with grain size, and was modelled as a logistic growth function with scale factor f0 and rate coefficient f1. Sticking efficiencies were found to be microorganism and filter specific, but the values of f0 and f1 were independent of microorganism and filter. Cross-validation showed that the model can be used to predict log removal of MS2 and ECWR1 within ±0.6 log. Within the range of operational conditions, the model shows that removal of microorganisms is most sensitive to changes in temperature and age of the Schmutzdecke. © 2013 Elsevier Ltd.

Hofman-Caris C.H.M.,KWR Watercycle Research Institute | Harmsen D.J.H.,KWR Watercycle Research Institute | Beerendonk E.F.,KWR Watercycle Research Institute | Knol A.H.,Dunea | And 3 more authors.
Ozone: Science and Engineering | Year: 2012

Advanced oxidation processes, are becoming important barriers against organic micropollutants in water treatment. To guarantee safe drinking water, it is important to be able to adjust the process parameters to the circumstances. Modeling can play an important role in this respect. Two models, UVPerox I and UVPerox II, were developed, in which the kinetic parameters of the process are combined with computational fluid dynamics (CFD), accounting for the hydrodynamics and UV irradiation distribution of the reactors applied. Both models were applied to several pilot reactors, and good accordance was observed between predicted and experimental data. © 2012 Copyright 2012 International Ozone Association.

Lekkerkerker-Teunissen K.,Dunea | Lekkerkerker-Teunissen K.,Technical University of Delft | Benotti M.J.,Applied Research and Development | Benotti M.J.,Batelle Memorial Institute | And 3 more authors.
Separation and Purification Technology | Year: 2012

Differences in the degradation and transformation of atrazine (ATZ), carbamazepine (CBZ), diclofenac (DCF), and sulfamethoxazole (SMX) in deionized water during UV and UV/H2O2 treatment using lowpressure (LP) and medium pressure (MP) UV lamps, were assessed using a collimated beam apparatus. UV doses ranged from 300700 mJ/cm2 and H 2O 2 doses ranged from 010 mg/L. Liquid chromatography with tandem mass spectrometry (LC-MS/MS) was used to measure concentrations of the parent compounds and quadrupole time-of-flight mass spectrometry (QToF-MS) was used to screen for transformation products following treatment. In general, there was little difference in compound degradation and transformation between LP and MP UV lamps in both UV and UV/H 2O 2 treatments. Removal of ATZ, SMX and DCF was largely attributed to direct photodegradation whereas CBZ was not appreciably removed by UV or UV/H 2O 2 treatment. All four compounds yielded transformation products following UV or UV/H 2O 2 treatment with LP and MP lamps. Transformation pathways were determined using accurate mass estimation to determine elemental composition, and relative abundance was determined using ion counts. For ATZ and CBZ, the transformation pathway was non-sequential, whereas for DCF and SMX, the transformation pathway was sequential. The approach outlined in this paper can be used to assess unknown transformation products formed during oxidation of organic micropollutants during water treatment. © 2012 Elsevier B.V. All rights reserved.

Bakker M.,Technical University of Delft | Vreeburg J.H.G.,Technical University of Delft | Vreeburg J.H.G.,KWR Watercycle Research Institute | Rietveld L.C.,Technical University of Delft | Van De Roer M.,Dunea
14th Water Distribution Systems Analysis Conference 2012, WDSA 2012 | Year: 2012

An method which compares measured and predicted water demands to detect anomalies, was developed and tested on three data sets of water demand of three years in which and 25 pipe bursts were reported. The method proved to be able to detect bursts where the water loss exceeds 30% of the average water demand in the area. By simultaneously running the method in adjacent supply areas, and combining the monitoring results the number of false alarms could be reduced. Further analysis of the reported bursts, showed that most burst (22 of 25) were isolated within 2 hours after occurrence. The anomaly detection method could not have reduced the number of Customer Minutes Lost (CML) of those bursts. The water loss and pressure drop of the other bursts was limited and caused no CML. The detection method was able to detect the bursts, but did not reduce the CML. Copyright © (2012) by Engineers Australia.

Van Thienen P.,KWR Watercycle Research Institute | Pieterse-Quirijns I.,KWR Watercycle Research Institute | Van De Roer M.,Dunea | Vreeburg J.,KWR Watercycle Research Institute | Vreeburg J.,Technical University of Delft
14th Water Distribution Systems Analysis Conference 2012, WDSA 2012 | Year: 2012

This paper presents a combination of two new approaches to leakage determination. The first approach is based on the classic bottom-up leakage determination, but uses a sophisticated demand model, SIMDEUM R, to estimate night demand. The second approach is a new analysis method for flow patterns, the Comparison of Flow Pattern Distributions (CFPD). This method allows distinguishing so called consistent from so called inconsistent changes in flow patterns. The latter includes leakage, the former does not. In an application of the first method, simulated demand is compared to measured demand for four different supply areas/DMAs. These examples illustrate cases with and without leakage, and difficulties related to the night demand of a large volume customer. CFPD analysis is applied to data from two areas. These applications illustrate, respectively, the identification and pinpointing (in time) of a small leak and the independent quantification of concurrent different types of changes with opposite signs in a supply pattern. In each case, the power of the CFPD block analysis is illustrated: discriminative quantification and visualization result in features and trends in complicated time series becoming apparent at a glance. Copyright © (2012) by Engineers Australia.

Hofman-Caris C.H.M.,KWR Watercycle Research Institute | Harmsen D.J.H.,KWR Watercycle Research Institute | Wols B.A.,KWR Watercycle Research Institute | Wols B.A.,Technical University of Delft | And 4 more authors.
Water Science and Technology: Water Supply | Year: 2011

Advanced oxidation processes, like UV/H2O2 oxidation, are important barriers against organic micro pollutants in drinking water treatment. In order to guarantee safe drinking water, it is important to be able to predict the reactors' performance to adjust the operating conditions to the actual influent water characteristics (like UV transmission) and lamp performance. Therefore, a design tool was developed, which is based on a kinetic model that describes and predicts the direct photolysis and oxidation of organic compounds in pilot experiments, using Low Pressure (LP) UV-lamps. This model has been combined with computational fluid dynamics (CFD), in order to be able to accurately predict the results of pilot and full scale installations, and also to design reactor systems. The model was applied to three model compounds (atrazine, ibuprofen and NDMA) in two different pilot reactors, and it has been shown that reactor performance can be fairly predicted by applying this 'UVPerox' model. The model takes into account the water quality and power of the lamps, and the properties of the compounds involved. © IWA Publishing 2011.

Hofman-Caris R.C.H.M.,KWR Watercycle Research Institute | Harmsen D.J.H.,KWR Watercycle Research Institute | Beerendonk E.F.,KWR Watercycle Research Institute | Knol T.H.,Dunea | And 3 more authors.
Chemical Engineering Journal | Year: 2012

The UV/H 2O 2 advanced oxidation process is increasingly applied as a barrier against organic micro pollutants in drinking water treatment. Adequate modeling of the purification process, resulting in a reliable prediction of the reactor performance, would make it possible to optimize the operating parameters as a function of seasonal or diurnal fluctuations in the influent composition, and thus save energy while still guaranteeing safe drinking water. We recently developed two design tools to predict full scale performance of UV/H 2O 2 reactors: the UVPerox I and II models. UVPerox I is based on a kinetic model, describing both photolysis and oxidation. By means of Computational Fluid Dynamics (CFD) calculations of the reactor the UV dose distribution inside the reactor can be calculated, while the kinetic model gives the conversion as a function of the UV dose. UVPerox I is shown to be applicable to reactors equipped with Low Pressure (LP) or Dielectric Barrier Discharge (DBD) UV lamps, using a broad range of organic compounds, resulting in a <5-10% deviation from experimental data for different water matrix compositions. The conversion of micro pollutants as a function of the UV dose can also be experimentally determined, using a collimated beam (CB) set-up. The dose response curves thus obtained can also be directly implemented in the CFD-model of the reactor (UVPerox II). Using several model compounds UVPerox II is shown to be applicable to reactors equipped with three kinds of UV lamps (LP-, MP- UV and DBD lamps), each with its own emission spectrum. The deviation from experimental data was found to be <5-10%, independent of the composition of the water matrix. Both models were applied to several reactor geometries. Good agreement was obtained between both models and the actual conversion data for three types of UV lamps in various pilot reactors and water types. © 2012 Elsevier B.V..

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