Separating NOM from salts in ion exchange brine with ceramic nanofiltration.

In drinking water treatment, natural organic matter (NOM) is effectively removed from surface water using ion exchange (IEX). A main drawback of using IEX for NOM removal is the production of spent IEX regeneration brine, a polluting waste that is expensive to discharge. In this work, we studied ceramic nanofiltration as a treatment for the spent NOM-rich brine, with the aim to reduce the volume of this waste and to recycle salt. Compared to polymeric nanofiltration, the fouling was limited. When NOM is rejected and concentrated, a clean permeate with the regeneration salt (NaCl) could be produced and reused in the IEX regeneration process. Bench scale studies revealed that NOM could be effectively separated from the NaCl solution by steric effects. However, the separation of NaCl from other salts present in the brine, such as Na2SO4, was not sufficient for reuse purposes. The low sulphate rejection was mainly due to the low zeta potential of the membrane at the high ionic strength of the brine. The permeate of the ceramic nanofiltration should be treated further to obtain a sodium chloride quality that can be recycled as a regenerant solution for ion exchange. Further treatment steps will benefit from the removal of NOM from the brine.

Arsenic removal from geothermal influenced groundwater with low pressure NF pilot plant for drinking water production in Nicaraguan rural communities.

This research evaluated the effect of different fluxes (16, 23 & 30 L/m2 h) and temperatures (31,35 & 43 °C) on the rejection of As(V) during nanofiltration (NF) of natural geothermal influenced groundwater in Nicaragua. A NF pilot plant powered by solar panels was built and operated in rural community Telica, exposed to As-rich drinking water sources due to geothermal influences. The results showed that even at high temperatures it is possible to obtain high rejection of As(V) (0.87-0.9) during NF filtration (recovery 10%; flux 16 L/m2 h) of geothermal influenced groundwater, with the additional advantage of requiring low operating pressures (1.2 bar ~ 12mwc). The permeate concentration (~5 µg/L) complied with the WHO guideline for drinking water and the concentrate (~55 µg/L) could be used by local villagers for daily activities (e.g., laundry and bathing). For all investigated fluxes and temperatures the order of rejection of As(V) (as HAsO42-), compared with the other anions, could be interpreted on the basis of its charge, hydrated radius and hydration free energy. At lower temperatures (31 and 35 °C) permeate quality improved slightly (~3 µg/L), but although an increased temperature had a negative effect on the As rejection, As concentrations in the permeate never exceeded 5 µg/L, while the required TMP dropped - depending on the flux - with 0.5 to 1 bar. This decrease in required pressure might be of huge benefit in deserted, rural locations where electricity is scarce, as with an overhead tank of 10-15 m a gravity-fed NF system would be feasible.

Arsenic contamination of rural community wells in Nicaragua: A review of two decades of experience.

Several surveys have been conducted in Nicaragua between 1996 and 2015 confirming the presence of high levels of arsenic (>10 µg/L). In this paper, these peer-reviewed (n = 2) and non-peer reviewed sources (n = 14) have been combined to provide an extensive overview of the arsenic contamination of drinking water sources in Nicaragua. So far, arsenic contamination has been detected in over 80 rural communities located in 34 municipalities of the country and arsenic poisoning has been identified in at least six of those communities. The source of arsenic contamination in Nicaragua is probably volcanic in origin, both from volcanic rocks and geothermal fluids which are distributed across the country. Arsenic may have directly entered into the groundwater by geothermally-influenced water bodies, or indirectly by reductive dissolution or alkali desorption, depending on the local geochemical conditions.

As(III) removal in rapid filters: Effect of pH, Fe(II)/Fe(III), filtration velocity and media size.

In the top layer of aerated rapid sand filtration systems, uncharged As(III) is biologically converted to charged As(V). Subsequently, the main removal mechanism for As(V) is adsorption onto oxidised, flocculated Fe(III) (hydrous ferric hydroxides; HFO). The aim of this research was to understand the interactions between As and Fe in biologically active rapid filter columns and investigate the effect of different operational modes on Fe removal to subsequently promote As removal. For this purpose, different filter media column experiments were performed using natural, aerated groundwater containing 3.4 µg/l As(III). Results show that independent of the filter media size, complete (biological) conversion of As(III), manganese, ammonium and nitrite was achieved in approximately 70 days. After ripening, enhanced As removal was achieved with a top layer of coarse media or by dosing additional Fe(III). Addition of Fe(II) did not have the same effect on As removal, potentially due to heterogeneous Fe(II) oxidation in the upper layer of the filter, attaching rapidly to the filter grain surface and thereby preventing HFO flocs to penetrate deeper into the bed. Increasing the flow rate from 1 to 4 m/h did not improve As removal and lowering the pH from 8 to 7.4, resulted in an 55% increased removal of dissolved As. Altogether it is concluded that As removal in biologically active rapid sand filters can be improved by applying coarser filter media on top, in combination with dosing Fe(III) and/or pH correction.

Effect of supernatant water level on As removal in biological rapid sand filters.

Current groundwater treatment facilities, mostly relying on aeration-filtration configurations, aim at the removal of iron (Fe), ammonia (NH4 +) and manganese (Mn). However, recently water companies expressed the ambition to also reduce arsenic (As) concentrations in these rapid sand filters. The aim of this study was to investigate the effect of the Fe oxidation state entering a biological filter bed on As removal. By varying supernatant water level, either Fe(II) or Fe(III) in the form of hydrous ferric oxides (HFO) could be stimulated to enter the filter bed at alkaline groundwater pH (7.6). The experimental pilot column filters showed that once the As(III) oxidation stabilised in the top layer of the filter sand, As removal reached its maximum (±75% at 120 cm supernatant level and 1.5 m/h filtration velocity). The increase in supernatant level from 5 to 120 cm resulted in additional HFO production prior to rapid filtration (1.5, 5 and 10 m/h), i.e. homogeneous Fe(II) oxidation and flocculation, and subsequently, HFO ending up deeper into the filter bed (120 cm filter depth). At a low supernatant water level of 5 cm, Fe(II) oxidised heterogeneously and was removed within the top 20 cm of the filter bed. Consequently, filters with high supernatant levels removed As to lower levels (by 20%) than in filters with low supernatant water levels. The benefits of Fe(II) oxidation prior to filtration for As removal was confirmed by comparing Fe(III) to Fe(II) additions in the supernatant water or in the filter bed. Overall it is concluded that in biological groundwater filters, the combination of a higher supernatant level and/or Fe(III) addition with biological As(III) oxidation in the top of the filter bed promotes As removal.

As(III) oxidation by MnO2 during groundwater treatment.

The top layer of natural rapid sand filtration was found to effectively oxidise arsenite (As(III)) in groundwater treatment. However, the oxidation pathway has not yet been identified. The aim of this study was to investigate whether naturally formed manganese oxide (MnO2), present on filter grains, could abiotically be responsible for As(III) oxidation in the top of a rapid sand filter. For this purpose As(III) oxidation with two MnO2 containing powders was investigated in aerobic water containing manganese(II) (Mn(II)), iron(II) (Fe(II)) and/or iron(III) (Fe(III)). The first MnO2 powder was a very pure - commercially available - natural MnO2 powder. The second originated from a filter sand coating, produced over 22 years in a rapid filter during aeration and filtration. Jar test experiments showed that both powders oxidised As(III). However, when applying the MnO2 in aerated, raw groundwater, As(III) removal was not enhanced compared to aeration alone. It was found that the presence of Fe(II)) and Mn(II) inhibited As(III) oxidation, as Fe(II) and Mn(II) adsorption and oxidation were preferred over As(III) on the MnO2 surface (at pH 7). Therefore it is concluded that just because MnO2 is present in a filter bed, it does not necessarily mean that MnO2 will be available to oxidise As(III). However, unlike Fe(II), the addition of Fe(III) did not hinder As(III) oxidation on the MnO2 surface; resulting in subsequent effective As(V) removal by the flocculating hydrous ferric oxides.

Clay-starch combination for micropollutants removal from wastewater treatment plant effluent.

In this study, a new, more effective and cost-effective treatment alternative is investigated for the removal of pharmaceuticals from wastewater treatment plant effluent (WWTP-eff). The potential of combining clay with biodegradable polymeric flocculants is further highlighted. Flocculation is viewed as the best method to get the optimum outcome from clay. In addition, flocculation with cationic starch increases the biodegradability and cost of the treatment. Clay is naturally abundantly available and relatively inexpensive compared to conventional adsorbents. Experimental studies were carried out with existing naturally occurring pharmaceutical concentrations found and measured in WWTP-eff with atrazine spiking for comparison between the demineralised water and WWTP-eff matrix. Around 70% of the total measured pharmaceutical compounds were removable by the clay-starch combination. The effect of clay with and without starch addition was also highlighted.

Improving health in cities through systems approaches for urban water management.

BACKGROUND: As human populations become more and more urban, decision-makers at all levels face new challenges related to both the scale of service provision and the increasing complexity of cities and the networks that connect them. These challenges may take on unique aspects in cities with different cultures, political and institutional frameworks, and at different levels of development, but they frequently have in common an origin in the interaction of human and environmental systems and the feedback relationships that govern their dynamic evolution. Accordingly, systems approaches are becoming recognized as critical to understanding and addressing such complex problems, including those related to human health and wellbeing. Management of water resources in and for cities is one area where such approaches hold real promise. RESULTS: This paper seeks to summarize links between water and health in cities and outline four main elements of systems approaches: analytic methods to deal with complexity, interdisciplinarity, transdisciplinarity, and multi-scale thinking. Using case studies from a range of urban socioeconomic and regional contexts (Maputo, Mozambique; Surat and Kolkata, India; and Vienna, Austria). CONCLUSION: We show how the inclusion of these elements can lead to better research design, more effective policy and better outcomes.

Fate of low arsenic concentrations during full-scale aeration and rapid filtration.

In the Netherlands, groundwater treatment commonly consists of aeration, with subsequent sand filtration without using chemical oxidants like chlorine. With arsenic (As) concentrations well below the actual guidelines of 10 µg As/L, groundwater treatment plants have been exclusively designed for the removal of iron (Fe), manganese and ammonium. The aim of this study was to investigate the As removal capacity at three of these groundwater treatment plants (10-26 µg As/L) in order to identify operational parameters that can contribute to lowering the filtrate As concentration to <1 µg/L. For this purpose a sampling campaign and experiments with supernatant water and hydrous ferric oxide (HFO) flocs were executed to identify the key mechanisms controlling As removal. Results showed that after aeration, As largely remained mobile in the supernatant water; even during extended residence times only 20-48% removal was achieved (with 1.4-4.2 mg/L precipitated Fe(II)). Speciation showed that the mobile As was in the reduced As(III) form, whereas, As(V) was readily adsorbed to the formed HFO flocs. In the filter bed, the remaining As(III) completely oxidized within 2 min of residence time and As removal efficiencies increased to 48-90%. Filter grain coating analysis showed the presence of manganese at all three treatment plants. It is hypothesized that these manganese oxides are responsible for the accelerated As(III) oxidation in the filter bed, leading to an increased removal capacity. In addition, pH adjustment from 7.8 to 7.0 has been found to improve the capacity for As(V) uptake by the HFO flocs in the filter bed. The overall conclusion is, that during groundwater treatment, the filter bed is crucial for rapid As(III) removal, indicating the importance to control the oxidation sequence of Fe and As for improved As removal efficiencies.

Familial liability for metoprolol-induced psychosis.

OBJECTIVE: Beta-blockers are commonly used in the treatment of hypertension and cardiac arrhythmias. The incidence of neuropsychiatric side effects is generally low. This case report shows the potential familial liability of a metoprolol-induced psychosis. METHOD: We report a case of metoprolol-induced psychosis. Potential pharmocogenetic factors mediating this familial metoprolol-induced psychosis are discussed. RESULTS: A middle-aged man developed psychosis after starting metoprolol, which diminished after ceasing the medication. Two of his family members experienced similar symptoms after using metoprolol. All family members were genotyped as CYP2D6*4 allele carriers indicating reduced CYP2D6 enzyme activity. CONCLUSION: The case presented here suggests a potential familial liability for metoprolol- induced psychosis. Pharmacokinetic mechanisms are hypothesized to mediate this familial liability through genetic variation in the CYP2D6 genotype. A family history of psychotic symptoms after treatment with beta-blockers should be taken into account, when prescribing this beta-blocker.

Performance of upflow gravel filtration in multi-stage filtration plants.

This paper presents the results of a study of four full-scale upflow gravel filters that are part of full-scale multi-stage filtration. The study explored the design criteria, the operation and maintenance (O&M) practices, and the performance of the systems. Findings showed that most design criteria and O&M procedures are following the recommendations as presented in the literature but several diversions were also identified. Performance data showed that removal efficiencies were on the low side when compared to the literature, possibly because of the good influent quality water that was treated. Cleaning efficiency was analyzed and the overall conclusion is that an adjustment of the design criteria and O&M procedures is needed to enhance system performance. This includes drainage system design, surface cleaning by weir, and filter bed cleaning to allow a reduction in cleaning cycles and an improvement in operation control.

[Trainee psychiatrists in residence need to be taught interactions skills]. / Training interactievaardigheden voor artsen in opleiding tot psychiater.

BACKGROUND: Trainee psychiatrists can find themselves in interactions where there is practically no collaboration with patients, their relatives, members of the treatment team and supervisors. A psychiatrist needs to be competent in establishing working relationships in complex situations and should be proficient in safeguarding professional boundaries. AIM: To evaluate the interaction skills training for first-year psychiatrist in residence at hospitals and clinics forming part of the East Netherlands Consortium. METHODS All trainee psychiatrists in residence were asked to complete two evaluation forms concerning the suitability of the skills training course, the first directly after the course ended and the second at follow-up 1 to 3 years later. RESULTS: The training was rated highly directly after the training (n=42, average 7.8) (scale 0-10) and at follow-up (n=23, average 7.7) (scale 0-10). 17 of the 23 respondents at follow-up stated that they felt the need for a refresher training course. CONCLUSION: The interaction skills training is greatly appreciated and satisfies the need of first-year psychiatrists to acquire the competence and skills that are important in complex situations.

Polyelectrolytes ability in reducing atrazine concentration in water: surface effects.

This paper reports on the direct ability of two positively charged organic polyelectrolytes (natural-based and synthetic) to reduce the atrazine concentration in water. The adsorption study was set up using multiple glass vessels with different polymer dosing levels followed by ultrafiltration with a 1 kDa membrane. The addition of polymers exhibited a capability in reducing the atrazine concentration up to a maximum of 60% in surface-to-volume ratio experiments. In the beginning, the theoretical L-type of the isotherm of Giles' classification was expected with an increase in the dosage of the polymer. However, in this study, the conventional type of isotherm was not observed. It was found that the adsorption of the cationic polymer on the negatively charged glass surface was necessary and influential for the removal of atrazine. Surface-to-volume ratio adsorption experiments were performed to elucidate the mechanisms and the polymer configuration. The glass surface area was determined to be a limiting parameter in the adsorption mechanism.

Forward osmosis for application in wastewater treatment: a review.

Research in the field of Forward Osmosis (FO) membrane technology has grown significantly over the last 10 years, but its application in the scope of wastewater treatment has been slower. Drinking water is becoming an increasingly marginal resource. Substituting drinking water for alternate water sources, specifically for use in industrial processes, may alleviate the global water stress. FO has the potential to sustainably treat wastewater sources and produce high quality water. FO relies on the osmotic pressure difference across the membrane to extract clean water from the feed, however the FO step is still mostly perceived as a "pre-treatment" process. To prompt FO-wastewater feasibility, the focus lies with new membrane developments, draw solutions to enhance wastewater treatment and energy recovery, and operating conditions. Optimisation of these parameters are essential to mitigate fouling, decrease concentration polarisation and increase FO performance; issues all closely related to one another. This review attempts to define the steps still required for FO to reach full-scale potential in wastewater treatment and water reclamation by discussing current novelties, bottlenecks and future perspectives of FO technology in the wastewater sector.

Struvite formation for enhanced dewaterability of digested wastewater sludge.

One of the main advantages of controlled struvite formation in digested sludge is an improvement in dewaterability of the digested sludge, which eventually leads to lower volumes of dewatered sludge that need to be transported. The effects of the control parameters for struvite formation, magnesium concentration and pH, on digested sludge dewaterability were investigated and are discussed in relation to the efficiency of struvite formation. Laboratory experiments with digested activated sludge were performed in a 20 L batch reactor. CO2 was stripped from the digested sludge using a bubble aerator and magnesium chloride was added to induce struvite formation. The dewaterability of the sludge was determined by gravity filtration tests. In the experiments, either the pH or the molar magnesium to phosphate ratio (Mg:PO4) was varied. The results confirm improved sludge dewaterability after struvite formation. Magnesium to phosphate ratios above 1.0 mol/mol did not further improve dewaterability. The addition of magnesium did not prevent the need for polymer addition for sludge dewatering. An increase in pH led to a deterioration in dewaterability. The best dewaterability results were found at the lowest pH value (pH = 7.0), while stirring the sludge instead of using the bubble aerator. At these settings, an orthophosphate removal of around 80% was achieved.

Quantification of continual anthropogenic pollutants released in swimming pools.

Disinfection in swimming pools is often performed by chlorination, However, anthropogenic pollutants from swimmers will react with chlorine and form disinfection by-products (DBPs). DBPs are unwanted from a health point of view, because some are irritating, while others might be carcinogenic. The reduction of anthropogenic pollutants will lead to a reduction in DBPs. This paper investigates the continual release of anthropogenic pollutants by means of controlled sweat experiments in a pool tank during laboratory time-series experiments (LTS experiments) and also during on-site experiments (OS experiments) in a swimming pool. The sweat released during the OS and LTS experiments was very similar. The sweat rate found was 0.1-0.2 L/m(2)/h at water temperatures below 29 °C and increased linearly with increasing water temperatures to 0.8 L/m(2)/h at 35 °C. The continual anthropogenic pollutant release (CAPR) not only consisted of sweat, particles (mainly skin fragments and hair) and micro-organisms, but also sebum (skin lipids) has to be considered. The release of most components can be explained by the composition of sweat. The average release during 30 min of exercise is 250 mg/bather non-purgeable organic carbon (NPOC), 77.3 mg/bather total nitrogen (TN), 37.1 mg/bather urea and 10.1 mg/bather ammonium. The release of NPOC cannot be explained by the composition of sweat and is most probably a result of sebum release. The average release of other components was 1.31 × 10(9) # particles/bather (2-50 µm), 5.2 µg/bather intracellular adenosine triphosphate (cATP) and 9.3 × 10(6) intact cell count/bather (iCC). The pool water temperature was the main parameter to restrain the CAPR. This study showed that a significant amount of the total anthropogenic pollutants release is due to unhygienic behaviour of bathers.

Effect of different temperatures on performance and membrane fouling in high concentration PAC-MBR system treating micro-polluted surface water.

A bench-scale immersed microfiltration coupled with 50 g/L PAC was developed to treat micro-polluted surface water (MPSW) under 10 and 20 °C and the effects of temperatures on the performance and the membrane fouling were also investigated. The low temperature (10 °C) delayed the time for the start-up by 9 days and the complete nitrification by 10 days. In the stable operation, two systems both had high NH3-N removal efficiency (above 90%) and better removal of organic matters (10% DOC, 5% UV254 and 4% SUVA) at 10 °C. Polysaccharides (SMP) were the main membrane fouling matters at low temperature (10 °C) and low temperature (10 °C) didn't cause serious chemical irreversible membrane fouling.

High concentration powdered activated carbon-membrane bioreactor (PAC-MBR) for slightly polluted surface water treatment at low temperature.

In this study, different concentrations of PAC combined with MBR were carried out to treat slightly polluted surface water (SPSW) at low temperature (10°C). Effects of PAC on the efficiencies of operation, treatment, and the performance of the process were investigated. It was found that the effluent quality, performance efficiency, resistance of shock load were all enhanced and chemical irreversible membrane fouling was reduced with increasing dosage of PAC in MBR. Only when the concentration of PAC which acted as biological carriers was high enough (i.g., 50 g/L), nitrification without initial inoculation in the filtration tank could start within 19 days and be completed within 35 days at 10°C. Fifty grams per liter PAC was the optimal dosage in MBR for stable and extended operation. Under this condition, mean removal efficiencies of ammonia nitrogen (NH(3)-N), dissolved organic carbon (DOC) and UV(254) were 93%, 75%, and 85%, respectively.

Phosphorus limitation in nitrifying groundwater filters.

Phosphorus limitation has been demonstrated for heterotrophic growth in groundwater, in drinking water production and distribution systems, and for nitrification of surface water treatment at low temperatures. In this study, phosphorus limitation was tested, in the Netherlands, for nitrification of anaerobic groundwater rich in iron, ammonium and orthophosphate. The bioassay method developed by Lehtola et al. (1999) was adapted to determine the microbially available phosphorus (MAP) for nitrification. In standardized batch experiments with an enriched mixed culture inoculum, the formation of nitrite and nitrate and ATP and the growth of ammonia-oxidizing bacteria (AOB; as indicated by qPCR targeting the amoA-coding gene) were determined for MAP concentrations between 0 and 100 µg PO4-P L(-1). The nitrification and microbial growth rates were limited at under 100 µg PO4-P L(-1) and virtually stopped at under 10 µg PO4-P L(-1). In the range between 10 and 50 µg PO4-P L(-1), a linear relationship was found between MAP and the maximum nitrification rate. AOB cell growth and ATP formation were proportional to the total ammonia oxidized. Contrary to Lehtola et al. (1999), biological growth was very slow for MAP concentrations less than 25 µg PO4-P L(-1). No full conversion nor maximum cell numbers were reached within 19 days. In full-scale groundwater filters, most of the orthophosphate was removed alongside with iron. The remaining orthophosphate appeared to have only limited availability for microbial growth and activity. In some groundwater filters, nitrification was almost totally prevented by limitation of MAP. In batch experiments with filtrate water from these filters, the nitrification process could be effectively stimulated by adding phosphoric acid.

Gallionella spp. in trickling filtration of subsurface aerated and natural groundwater.

The growth of iron-oxidizing bacteria, generally regarded as obligate microaerophilic at neutral pH conditions, has been reported in a wide range of environments, including engineered systems for drinking water production. This research focused on intensively aerated trickling filters treating deep anaerobic and subsurface aerated groundwater. The two systems, each comprising groundwater abstraction and trickling filtration, were monitored over a period of 9 months. Gallionella spp. were quantified by qPCR with specifically designed 16S rRNA primers and identified directly in the environmental samples using clone libraries with the same primers. In addition, enrichments in gradient tubes were evaluated after DGGE separation with general bacterial primers. No other iron-oxidizing bacteria than Gallionella spp. were found in the gradient tubes. qPCR provided an effective method to evaluate the growth of Gallionella spp. in these filter systems. The growth of Gallionella spp. was stimulated by subsurface aeration, but these bacteria hardly grew in the trickling filter. In the uninfluenced, natural anaerobic groundwater, Gallionella spp. were only present in low numbers, but they grew extensively in the trickling filter. Identification revealed that Gallionella spp., growing in the trickling filter were phylogenetically distinct from the species found growing during subsurface aeration, indicating that the different conditions in both systems selected for niche organisms, while inhibiting other groups. The results suggest a minor direct significance for inoculation of Gallionella spp. during filtration of subsurface aerated groundwater.