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Apeldoorn, Netherlands

Lekkerkerker-Teunissen K.,Dunea Duin en Water | Lekkerkerker-Teunissen K.,Technical University of Delft | Knol A.H.,Dunea Duin en Water | Van Altena L.P.,Dunea Duin en Water | And 3 more authors.
Separation and Purification Technology | Year: 2012

Serial ozone/peroxide/low pressure UV was tested for an advanced oxidation process (AOP) application on pre-treated surface water in a pilot plant. The pilot plant consisted of an ozone loop reactor followed by a low pressure UV (LP-UV) reactor. Fourteen model compounds and 6 or 10 ppm hydrogen peroxide were dosed to the water. Ozone doses varied from 0.5 to 2.0 g/m 3 and UV doses varied, depending on the UV transmission (73-83%) of the water, between 700 and 950 mJ/cm 2. The treatment process was evaluated on bromate formation, compound conversion and energy demand. The bromate formation during the O 3/H 2O 2 process was kept lower than 0.5 μg/L by using a peroxide dose of 6 ppm and an ozone dose of 1.5 mg/L. With a 1.5 mg/L ozone dose and 6 ppm of peroxide, 8 out of 14 compounds were converted by more than 90% with an energy consumption of 0.027 kW h/m 3. During the subsequent UV/H 2O 2, the E EO for atrazine was 0.52 kW h/m 3; together with the O 3/H 2O 2, the E EO for serial AOP was 0.55 kW h/m 3, which was 0.73 kW h/m 3 for UV/H 2O 2 only. During O 3/H 2O 2 treatment, the DOC decreased with 0.2 mg/L and the UV-T 254 increased with almost 5%, illustrating the synergistic effect of serial AOP. When 3 UV reactors in series were used, with each reactor dosing 1/3 of the total dose, the total conversion increased 5-15%. © 2012 Elsevier B.V. All rights reserved. Source

Bazri M.M.,University of British Columbia | Martijn B.,PWN Technologies andijk | Kroesbergen J.,Het Waterlaboratorium | Mohseni M.,University of British Columbia
Chemosphere | Year: 2016

The formation potential of carbonaceous and nitrogenous disinfection by-products (C-DBPs, N-DBPs) after ion exchange treatment (IEX) of three different water types in multiple consecutive loading cycles was investigated. Liquid chromatography with organic carbon detector (LC-OCD) was employed to gauge the impact of IEX on different natural organic matter (NOM) fractions and data obtained were used to correlate these changes to DBPs Formation Potential (FP) under chlorination. Humic (-like) substances fractions of NOM were mainly targeted by ion exchange resins (40-67% removal), whereas hydrophilic, non-ionic fractions such as neutrals and building blocks were poorly removed during the treatment (12-33% removal). Application of ion exchange resins removed 13-20% of total carbonaceous DBPs FP and 3-50% of total nitrogenous DBPs FP. Effect of the inorganic nitrogen (i.e., Nitrate) presence on N-DBPs FP was insignificant while the presence of dissolved organic nitrogen (DON) was found to be a key parameter affecting the formation of N-DBPs. DON especially the portion affiliated with humic substances fraction, was reduced effectively (~77%) as a result of IEX treatment. © 2015 Elsevier Ltd. Source

van Lieverloo J.H.M.,KWR Watercycle Research Institute | Hoogenboezem W.,Het Waterlaboratorium | Veenendaal G.,WLN Waterlaboratorium Noord | van der Kooij D.,KWR Watercycle Research Institute
Water Research | Year: 2012

A survey of invertebrates in drinking water from treatment works, internal taps and hydrants on mains was carried out by almost all water companies in the Netherlands from September 1993 to August 1995. Aquatic sow bugs (Asellidae, 1-12 mm) and oligochaeta worms (Oligochaeta, 1-100 mm), both known to have caused rare though embarrassing consumer complaints, were found to form 98% of the mean biomass in water flushed from mains. Their numbers in the mains water ranged up to 1500 (mean 37) Asellidae m-3 and up to 9900 (mean 135) Oligochaeta m-3. Smaller crustaceans (0.5-2 mm) dominated the numbers in water from mains. e.g. water fleas (Cladocera and Copepoda up to 14,000 m-3). Common invertebrates in treated water and in tap water were Rotifera (<1 mm) and nematode worms (Nematoda, <2 mm). No Asellidae, large Oligochaeta (>5 mm) or other large invertebrates were found in 1560 samples of 200 l treated water or tap water.Large variations in invertebrate abundance were found within and between distribution systems. Of the variability of mean biomass in mains per system, 55%, 60% and 63% could statistically be explained by differences in the Biofilm Formation Rate, non-particulate organic matter and the permanganate index of the treated water of the treatment works respectively. A similar correlation was found between mean invertebrate biomass and mean sediment volumes in the distribution systems (R2 = 52%). © 2012 Elsevier Ltd. Source

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. Source

van der Kooij D.,KWR Watercycle Research Institute | Martijn B.,PWN Technologies | Schaap P.G.,Water Supply Company Noord Holland PWN | Hoogenboezem W.,Het Waterlaboratorium | And 2 more authors.
Water Research | Year: 2015

Assessment of drinking-water biostability is generally based on measuring bacterial growth in short-term batch tests. However, microbial growth in the distribution system is affected by multiple interactions between water, biofilms and sediments. Therefore a diversity of test methods was applied to characterize the biostability of drinking water distributed without disinfectant residual at a surface-water supply. This drinking water complied with the standards for the heterotrophic plate count and coliforms, but aeromonads periodically exceeded the regulatory limit (1000 CFU 100 mL-1). Compounds promoting growth of the biopolymer-utilizing Flavobacterium johnsoniae strain A3 accounted for c. 21% of the easily assimilable organic carbon (AOC) concentration (17 ± 2 μg C L-1) determined by growth of pure cultures in the water after granular activated-carbon filtration (GACF). Growth of the indigenous bacteria measured as adenosine tri-phosphate in water samples incubated at 25 °C confirmed the low AOC in the GACF but revealed the presence of compounds promoting growth after more than one week of incubation. Furthermore, the concentration of particulate organic carbon in the GACF (83 ± 42 μg C L-1, including 65% carbohydrates) exceeded the AOC concentration. The increased biomass accumulation rate in the continuous biofouling monitor (CBM) at the distribution system reservoir demonstrated the presence of easily biodegradable by-products related to ClO2 dosage to the GACF and in the CBM at 42 km from the treatment plant an iron-associated biomass accumulation was observed. The various methods applied thus distinguished between easily assimilable compounds, biopolymers, slowly biodegradable compounds and biomass-accumulation potential, providing an improved assessment of the biostability of the water. Regrowth of aeromonads may be related to biomass-turnover processes in the distribution system, but establishment of quantitative relationships is needed for confirmation. © 2015 Elsevier Ltd. Source

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