Time filter

Source Type

Voorburg, Netherlands

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.

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.

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 | Chekol E.T.,UNESCO-IHE Institute for Water Education | Maeng S.K.,Sejong University | And 9 more authors.
Water Science and Technology: Water Supply | Year: 2012

Organic micropollutants (OMPs) are detected in sources for drinking water and treatment possibilities are investigated. Innovative removal technologies are available such as membrane filtration and advanced oxidation, but also biological treatment should be considered. By combining an advanced oxidation process with managed aquifer recharge (MAR), two complementary processes are expected to provide a hybrid system for OMP removal, according to the multiple barrier approach. Laboratory scale batch reactor experiments were conducted to investigate the removal of dissolved organic carbon (DOC) and 14 different pharmaceutically active compounds (PhACs) from MAR influent water and water subjected to oxidation, under different process conditions. A DOC removal of 10% was found in water under oxic (aerobic) conditions for batch reactor experiments, a similar value for DOC removal was observed in the field. Batch reactor experiments for the removal of PhACs showed that the removal of pharmaceuticals ranged from negligible to more than 90%. Under oxic conditions, seven out of 14 pharmaceuticals were removed over 90% and 12 out of 14 pharmaceuticals were removed at more than 50% during 30 days of experiments. Under anoxic conditions, four out of 14 pharmaceuticals were removed over 90% and eight out of 14 pharmaceuticals were removed at more than 50% over 30 days' experiments. Carbamazepine and phenazone were persistent both under oxic and anoxic conditions. The PhACs removal efficiency with oxidized water was, for most compounds, comparable to the removal with MAR influent water. Copyright © IWA Publishing 2012.

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.

Discover hidden collaborations