Danny J. H. Harmsen

KWR Water Research Institute · drinking water treatment

The ever-increasing production and use of chemicals lead to the occurrence of organic micro-pollutants (OMPs) in drinking water sources, and consequently the need for their removal during drinking water treatment. Due to the sheer number of OMPs, monitoring using targeted chemical analyses alone is not sufficient to assess drinking water quality as...

In several places in The Netherlands, industrial areas are redeveloped into residential areas with sustainable heating systems based on aquifer thermal energy storages (ATES). At these sites, groundwater is contaminated with chlorinated ethenes. In this project various pilot set-ups were tested as a non-invasive technique to remove chlorinated ethe...

Increasing concentrations of organic micropollutants, like pharmaceuticals, in surface water may require additional treatment for drinking water production. The UV/H2O2 process is very effective for this purpose, but is known for its relatively high energy demand. This energy demand may be decreased by improving the water matrix composition and/or...

Literature data on of the effect of calcium on biofilm structures induced a preliminary study. The effect of calcium removal by water softening (<1.0 mg Ca 2þ .L À1) under real-world drinking water conditions on biofilm formation was studied in a pilot plant with reversed osmosis (RO) membranes and in a laboratory-scale biofilm production unit (BPU...

The design of UV/H2O2 reactors is studied. First an analytical approach is followed that provides characteristics (maximum fluence and maximum possible degradation) for an ideal system. An efficiency parameter is introduced that relates the actual performance of a reactor with the best possible performance for a reactor with a certain water flow, l...

UV/H2O2 treatment is a well-established technique to degrade organic micropollutants. A CFD model in combination with an advanced kinetic model is presented to predict the degradation of organic micropollutants in UV (LP)/H2O2 reactors, accounting for the hydraulics, fluence rate, complex (photo)chemical reactions in the water matrix and the intera...

UV/H2O2 processes in drinking water treatment may generate byproducts which cause an increased response in Ames fluctuation assays. As this probably involves a mixture of substances in very low concentrations, it is challenging to identify the individual byproducts. Therefore it was studied under which conditions mutagenic byproducts are formed and...

Forward osmosis (FO) processes, due to internal concentration polarisation, are limited with regards to flux. Improved flux performance will allow FO to compete with fluxes achieved by hydraulically driven membrane processes. Pressure assisted osmosis (PAO) is proposed to enhance FO performance, by adding hydraulic pressure (0.1-0.8 bar) on the fee...

Pharmaceuticals and other organic micropollutants are increasingly found in water sources. The UV/H2O2 process is a suitable technology to degrade these pharmaceuticals. A kinetic model is presented to predict pharmaceutical degradation during UV/H2O2 treatment. Reactions with background constituents in the water matrix, such as (bi)carbonate, nitr...

UV/H2O2 processes can be studied using a Collimated Beam (CB) set-up. In UV dose calculations, the “water factor” accounts for changes in the irradiation spectrum upon its way through the aqueous solution. Analogous to the “germicidal factor”, the “extinction factor” is introduced, correcting for the fact that compounds as a result will be subjecte...

The draw solution is the driving force in forward osmosis (FO) processes. The reverse solute leakage of the draw solution is however a major constraint due to cost and energy requirements when reconcentrating the solutes subsequent to the FO process. Several zwitterions as draw solutions (π≈24 bar and 7 bar) were systematically investigated to enha...

The properties and performance of a recently developed thin film nanocomposite (TFN), with inorganic nanoparticles incorporated in the active layer, and standard thin Film composite (TFC) spiral wound seawater desalination reverse osmosis (RO) membranes were assessed by comparison on the scale of 4040 and 8040 membrane modules. Scanning electron mi...

The occurrence of pharmaceuticals in source waters is increasing. Although UV advanced oxidation is known to be an effective barrier against micropollutants, degradation rates are only available for limited amounts of pharmaceuticals. Therefore, the degradation of a large group of pharmaceuticals has been studied in this research for the UV/H2O2 pr...

The properties and performance of a recently developed thin film nanocomposite (TFN), with inorganic nanoparticles incorporated in the active layer, and standard thin film composite (TFC) spiral wound seawater desalination reverse osmosis (RO) membranes were assessed by comparison on the scale of 4040 and 8040 membrane modules. Scanning electron mi...

This paper describes the results of experiments performed in a high-recovery system to elucidate the silica scaling phenomenon and characterize the scaling. In this research, cation exchange pretreatment is used to reduce Ca2+, Ba2+, and Mg2+ levels to prevent scaling during subsequent nanofiltration (NF) and reverse osmosis (RO) filtration, in whi...

This paper investigated silica and silicate precipitation as limiting factors in high-recovery membrane operations. For this purpose a cation exchange pretreatment is proposed to reduce Ca 2+, Ba 2+, Mg 2+ levels to prevent scaling of salts containing these ions during subsequent NF and RO filtration, in which RO is fed with NF concentrate. In a pi...

The UV/H2O2 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 fluct...

Cleaning of high pressure RO/NF membranes is an important operational tool to control biofouling. Quantitative information on the efficacy of cleaning agents and protocols to remove biomass is scarce. Therefore, a laboratory cleaning test to assess the efficiency of cleaning procedures to remove attached biomass was developed. The major components...

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...

Research into the conversion of organic micropollutants revealed that with medium pressure (MP) UV-lamps, an increase in genotoxic activity in one of two tested bacterial strains in the Ames II test may be obtained. To study the factors that affect formation of genotoxic by-products, volumes ≥ 500 mL are required. It is possible to use a collimated...

Computational fluid dynamics (CFD) is becoming increasingly popular for assessing UV reactor performance. However, due to uncertainties in flow fields, lamp output and microbial response to UV, the CFD model needs to be validated by measurements. The combination of several experimental techniques with CFD modeling allows for a thorough understandin...

Spiral-wound membrane (SWM) elements for nanofiltration (NF) and reverse osmosis (RO) need pre-treatment to prevent clogging of the feed spacer channel by particles and/or biomass. Usually rapid sand filtration or ultrafiltration is applied for this purpose. The effect of (the removal of) particles on biofouling processes in spiral-wound membrane (...

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) a...

Forward osmosis (FO) is a concentration driven membrane process which recently gained an increase in attention due to the development of improved FO membranes. Most of the currently available data on FO research is obtained on small laboratory-scale set-ups, thereby overlooking the effects of scaling-up to pilot or full-scale size. In this paper, F...

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...

The objective of this study was to determine the genotoxic activity of water after UV/H(2)O(2) oxidation and GAC filtration. Pre-treated surface water from three locations was treated with UV/H(2)O(2) with medium pressure (MP) lamps and passed through granulated activated carbon (GAC). Samples taken before and after each treatment step were extract...

An innovative osmotic membrane bioreactor (OMBR) is currently under development for the reclamation of wastewater, which combines activated sludge treatment and forward osmosis (FO) membrane separation with a RO post-treatment. The research focus is FO membrane fouling and performance using different activated sludge investigated both at laboratory...

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....

To improve hydraulic conditions, periodic air/water cleaning (AWC) is applied to a nanofiltration (NF) spiral wound membrane (SWM) element under permeation conditions to control biofouling and particulate fouling. A pilot study was carried out for 212 days with a vertically positioned SWM element fed by tap water enriched with a biodegradable compo...

An innovative osmotic membrane bioreactor (OMBR) is currently under development, based on forward osmosis (FO) driven by an osmotic pressure difference. For the OMBR to be both technically and economically viable, the performance of the FO membranes has to be sufficiently high, while membrane fouling and draw solution leakage has to be low. The eff...