Diazepam stability in wastewater and removal by advanced membrane technology, activated carbon, and micelle–clay complex
. Desalination and Water Treatment 2016
, 3098-3106. Publisher's VersionAbstract
Stability and removal of the anti-anxiety drug diazepam (valium) from spiked wastewater samples were studied. An advanced wastewater treatment plant (WWTP), utilizing ultrafiltration (UF), activated charcoal (AC), and reverse osmosis (RO) after the secondary biological treatment showed that UF and RO were relatively sufficient in removing spiked diazepam to a safe level. Kinetic studies in both pure water (abiotic degradation) and in sludge (biotic degradation) at room temperature were investigated. Diazepam showed high chemical stability toward degradation in pure water, and underwent faster biodegradation in sludge providing two main degradation products. The degradation reactions in sludge and pure water showed first-order kinetics with rate constant values of 2.6 × 10−7 s−1 and 9.08 × 10−8 s−1, respectively (half-life = 31 and 88 d, respectively). Adsorption of diazepam by activated carbon and composite micelle–clay (octadecyltrimethylammonium montmorillonite) complex was studied using both Langmuir and Freundlich isotherms. Based on the determination coefficient, Langmuir isotherm was found to better fit the data, indicating the retention of diazepam monolayer on both adsorbents. Filtration of 100 mg L−1 solutions of diazepam by micelle–clay filter yielded almost complete removal at flow rates of 2 mL min−1. © 2014 Balaban Desalination Publications. All rights reserved.
Paracetamol biodegradation by activated sludge and photocatalysis and its removal by a micelle–clay complex, activated charcoal, and reverse osmosis membranes
. Environmental Technology (United Kingdom) 2016
, 2414-2427. Publisher's VersionAbstract
Kinetic studies on the stability of the pain killer paracetamol in Al-Quds activated sludge demonstrated that paracetamol underwent biodegradation within less than one month to furnish p-aminophenol in high yields. Characterizations of bacteria contained in Al-Quds sludge were accomplished. It was found that Pseudomonas aeruginosa is the bacterium most responsible for the biodegradation of paracetamol to p-aminophenol and hydroquinone. Batch adsorptions of paracetamol and its biodegradation product (p-aminophenol) by activated charcoal and a composite micelle (octadecyltrimethylammonium)–clay (montmorillonite) were determined at 25°C. Adsorption was adequately described by a Langmuir isotherm, and indicated better efficiency of removal by the micelle–clay complex. The ability of bench top reverse osmosis (RO) plant as well as advanced membrane pilot plant to remove paracetamol was also studied at different water matrixes to test the effect of organic matter composition. The results showed that at least 90% rejection was obtained by both plants. In addition, removal of paracetamol from RO brine was investigated by using photocatalytic processes; optimal conditions were found to be acidic or basic pH, in which paracetamol degraded in less than 5 min. Toxicity studies indicated that the effluent and brine were not toxic except for using extra low energy membrane which displayed a half maximal inhibitory concentration (IC-50) value of 80%. © 2016 Taylor & Francis.
Purification of greywater by a moving bed reactor followed by a filter including a granulated micelle-clay composite
. Applied Clay Science 2016
, 267-272. Publisher's VersionAbstract
Reuse of grey water (GW) enables to reduce fresh water consumption, but a treatment is required to prevent potential transmission and propagation of pathogenic organisms. This study presents results on the removal of pathogenic bacteria from GW as well as reduction of turbidity, TSS COD, and BOD by a novel treatment system. Compared to previous studied methods, three new elements are presented in the current treatment of GW: (1) A granulated complex of micelles of the organic cation octadecyltrimethylammonium (ODTMA) with montmorillonite was employed in filtration of GW. This complex was efficient in purifying GW due to its large surface area, positive charge and existence of hydrophobic domains. The granulated complex enabled flow when present exclusively in the filter; (2). A moving bed reactor for decomposition of part of the organic matter in the GW. This pretreatment stage, prior to the micelle-clay filter, was also efficient in removing pathogenic bacteria; (3) A regeneration stage of the micelle-clay filter conducted by passing either dilute solutions of Na-hypochlorite or HCl through the micelle-clay complex, or by heating the complex. Incubation of GW for either two weeks or one day in the pretreatment stage yielded a 10- and 7-fold enhancement in the volume filtered, which did not contain fecal coliforms, i.e., 300 and 210 L for 40 g of complex, respectively. The capacity of purified volume per gram of the complex increased further several-fold (> 23 L/g) for filters filled exclusively with granules. Regeneration of the complex in the filter further enhanced the capacity. © 2016 Elsevier B.V.
The impact of rainfall-runoff events on the water quality of the upper catchment of the Jordan River, Israel
; Integrated Water Resources Management: Concept, Research and Implementation; 2016; pp. 129-146. Publisher's VersionAbstract
This study examined the influence of rainfall-runoff events on water quality of the Upper Catchment of the Jordan River (UCJR) with a special emphasize on P fate and transport. We sampled 60 locations across the catchment to test the hypothesis that under Mediterranean climate conditions, most of the nutrient losses from the fields to waterways will occur in few major events while the actual contributing areas will be limited to critical source areas (CSA). Water analyses included nutrients (SRP, TP, TSS, NO3, & NH4), fecal indicators (Fecal Coliforms, E-Coli and Enterococcus) and EC & pH. Spatial analysis was conducted to identify CSA. In general, the results demonstrated the influence of runoff events on the water quality in the UCJR and the high heterogeneity of these events in space and time. The study showed that the levels of SRP, TP, TSS as well as indicators of fecal contamination were primarily transported with surface runoff and increased significantly in the stream during these events. Phosphorous concentrations in some sub-catchments reached extremely high concentrations (19 mg/l) during runoff compared with an average of 1.9 mg/l for the entire watershed. The medium to high correlation between the fecal indicators, total P and TSS suggest that during runoff events, P and bacteria attached to soil particles were mobilized to the stream from CSA. Water sampling along the streams flow paths together with the spatial analysis, identified CSA where an elevated nutrient concentration has been identified. Autocorrelation test identified CSA where an external pollution source influences the water nutrients content. The study provides watershed management science-based remediation options to reduce the potential of water pollution during major rainfall-runoff events. © Springer International Publishing Switzerland 2016. All rights are reserved.
A novel automated method for the adjustment of ionic metal concentrations in soil extracts
. Journal of Plant Nutrition and Soil Science 2016
, 615-617. Publisher's VersionAbstract
A novel method is proposed for correcting metal fraction concentrations remaining within the sediment containing the solid residue of the sequentially extracted fraction. An easy-to-use Excel spreadsheet was prepared to assist adjustment of concentration in each fraction and demonstrate the difference between adjusted and non-adjusted metal concentration of the fraction. The demonstration of a calculation of the modified BCR protocol data showed that this difference may reach 10–15% of the result value. The spreadsheet is available to download at: http://departments.agri.huji.ac.il/zabam/Rosen_Chen_Fraction_Adjustment_...
. Copyright © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
The use of treated wastewater for irrigation as a component of integrated water resources management: Reducing environmental implications on soil and groundwater by evaluating site-specific soil sensitivities
; Integrated Water Resources Management: Concept, Research and Implementation; 2016; pp. 459-470. Publisher's VersionAbstract
The use of non-conventional water resources like treated wastewater (TWW) is a contribution to alleviate the pressure on available natural water resources in water scarce regions, as it allows higher quality water to be available for other purposes. Population growth, improved living standards and expected climate change impacts will raise the importance of water reuse progressively. TWW can be utilized for various purposes, such as for irrigation, conservation, groundwater recharge or domestic and industrial use. In the eastern Mediterranean region, irrigation with water of marginal quality has a long history, with Israel being the promoting pioneer in advanced treated wastewater use policy and technology. However, apart from health and crop quality concerns, there are potential adverse effects of TWW application on soil and groundwater quality to be considered. In aiming to avoid unsustainable exposures, the regional risks related with TWW irrigation have to be specified and differentiated according to regional soil properties. Within the multinational joint research project network GLOWA (Global Change and the Hydrological Cycle) Jordan River, a regional based land evaluation was conducted for the area of Israel, Jordan and the Palestinian Authority by combining supraregional spatial soil data using a geographic information system (GIS). These data were used to identify land more or less sensitive towards TWW irrigation and for the implementation in regional decision support systems (DSS) related to water allocation and the extension of irrigation infrastructure. © Springer International Publishing Switzerland 2016. All rights are reserved.
Modeling the movement of water and solute through preferential flow paths and fractures
. In The Handbook of Groundwater Engineering: Third Edition
; The Handbook of Groundwater Engineering: Third Edition; 2016; pp. 509 - 530. Publisher's Version
Formation of soil–water repellency in olive orchards and its influence on infiltration pattern
, 1 - 11. Publisher's VersionAbstract
Water-repellent (hydrophobic) soils do not wet instantaneously, but only after some time (a few seconds to hours) of soil-particle contact with water. Some plant species can render soils hydrophobic but in this respect, olive trees have scarcely been examined. Measurements of water repellency in olive orchards of different ages in different locations in Israel using the water drop penetration time (WDPT) test have shown that soils tend to become hydrophobic, regardless of texture and structure. A comprehensive study was then performed for an irrigated young and mature olive grove and nearby uncultivated bare soil in the southern part of Israel. The study included intensive WDPT measurements, initial (repellency intensity) and rate of decrease (repellency persistence) for sessile drops placed on the soil surface, cumulative infiltration using tension disc infiltrometer, and monitoring flow in a transparent flow chamber packed with soils from the different plots. The soil from the mature olive plot was noticeably more water repellent than the young plot's soil, and both differed from the uncultivated soil that was fully wettable. The contact angle of a drop placed on the surface of a single layer of soil particles decreased exponentially with time, with a lower decay rate for the mature orchard soil. Cumulative infiltration had a convex pattern for wettable soils and a concave pattern for water-repellent ones. The difference in infiltration pattern was attributed to water/pressure buildup behind the wetting front as a result of the dynamic contact-angle-induced pore resistivity to wetting. The supplemental pressure, also known as dynamic water-entry pressure, increases the infiltration rate beyond that obtained by the capillary pressure per se. The significant correlation between soil sorptivity and the asymptotic infiltration rate, both calculated from the cumulative infiltration curves, and the WDPT substantiates the dependence of pressure overshoot and the rate at which the contact angle decreases prior to pore wetting. The considerable differences in plume shape, size, and internal saturation distribution between the wettable and water-repellent soils, indicating unstable flow in the latter, were also explained by the wettability-dependent water-entry pressure. The outcome of this study indirectly supports the findings that higher surface runoff and erosion are associated with no-till farming in olive orchards, due to the combination of no-till cropping and the near-surface accumulation of hydrophobic organic carbon compounds.
Kinetics of gravity-driven slug flow in partially wettable capillaries of varying cross section
. Water Resources Research 2016
, 8472-8486. Publisher's VersionAbstract
Abstract A mathematical model for slug (finite liquid volume) motion in not-fully-wettable capillary tubes with sinusoidally varying cross-sectional areas was developed. The model, based on the Navier-Stokes equation, accounts for the full viscous terms due to nonuniform geometry, the inertial term, the slug's front and rear meniscus hysteresis effect, and dependence of contact angle on flow velocity (dynamic contact angle). The model includes a velocity-dependent film that is left behind the advancing slug, reducing its mass. The model was successfully verified experimentally by recording slug movement in uniform and sinusoidal capillary tubes with a gray-scale high-speed camera. Simulation showed that tube nonuniformity has a substantial effect on slug flow pattern: in a uniform tube it is monotonic and depends mainly on the slug's momentary mass/length; an undulating tube radius results in nonmonotonic flow characteristics. The static nonzero contact angle varies locally in nonuniform tubes owing to the additional effect of wall slope. Moreover, the nonuniform cross-sectional area induces slug acceleration, deceleration, blockage, and metastable-equilibrium locations. Increasing contact angle further amplifies the geometry effect on slug propagation. The developed model provides a modified means of emulating slug flow in differently wettable porous media for intermittent inlet water supply (e.g., raindrops on the soil surface).
Effects of nitrogen nutrition on disease development caused by Acidovorax citrulli on melon foliage
, 125 - 137. Publisher's VersionAbstract
Bacterial fruit blotch (BFB) of cucurbits, caused by the seed-borne bacterium Acidovorax citrulli, is a destructive disease that threatens the melon and watermelon industries worldwide. The available means to manage the disease are very limited and there are no reliable sources of BFB resistance. Mineral nutrition has marked effects on plant diseases. To the best of our knowledge, no studies reporting effects of mineral nutrition on BFB severity have been reported to date. In the present study we assessed the influence of nitrogen nutrition on BFB severity and A. citrulli establishment in the foliage of melon plants under greenhouse conditions. Our results show that nitrogen fertilization, based on nitrate only, led to reduced disease severity and bacterial numbers in melon leaves, as compared with two combinations of nitrate and ammonium. No consistent effect of nitrogen nutrition on expression of several plant defense-associated transcripts was found, except for hydroperoxide lyase (HPL), which upon inoculation was repressed to a greater extent under the “nitrate-only” nitrogen regime compared with combined nitrate and ammonium. Reducing BFB severity and A. citrulli establishment in the plant foliage are of particular importance since establishment of the pathogen during the growing season is assumed to increase the incidence of fruit infection, leading to serious yield losses. Further research is needed to elucidate the mechanisms by which nitrogen nutrition influences BFB development, and to assess the effects of nitrogen as well as other minerals on the disease under field conditions.
The impact of mucilage on root water uptake—A numerical study
. Water Resources Research 2016
, 264-277. Publisher's VersionAbstract
Abstract The flow of water between soil and plants follows the gradient in water potential and depends on the hydraulic properties of the soil and the root. In models for root water uptake (RWU), it is usually assumed that the hydraulic properties near the plant root (i.e., in the rhizosphere) and in the bulk soil are identical. Yet a growing body of evidence has shown that the hydraulic properties of the rhizosphere are affected by root exudates (specifically, mucilage) and markedly differ from those of the bulk soil. In this work, we couple a 3-D detailed description of RWU with a model that accounts for the rhizosphere-specific properties (i.e., rhizosphere hydraulic properties and a nonequilibrium relation between water content and matric head). We show that as the soil dries out (due to water uptake), the higher water holding capacity of the rhizosphere results in a delay of the stress onset. During rewetting, nonequilibrium results in a slower increase of the rhizosphere water content. Furthermore, the inverse relation between water content and relaxation time implies that the drier is the rhizosphere the longer it takes to rewet. Another outcome of nonequilibrium is the small fluctuation of the rhizosphere water content compared to the bulk soil. Overall, our numerical results are in agreement with recent experimental data and provide a tool to further examine the impact of various rhizosphere processes on RWU and water dynamics.
Optimal control solutions to sodic soil reclamation
. Advances in Water Resources 2016
, 37 - 45. Publisher's VersionAbstract
We study the reclamation process of a sodic soil by irrigation with water amended with calcium cations. In order to explore the entire range of time-dependent strategies, this task is framed as an optimal control problem, where the amendment rate is the control and the total rehabilitation time is the quantity to be minimized. We use a minimalist model of vertically averaged soil salinity and sodicity, in which the main feedback controlling the dynamics is the nonlinear coupling of soil water and exchange complex, given by the Gapon equation. We show that the optimal solution is a bang–bang control strategy, where the amendment rate is discontinuously switched along the process from a maximum value to zero. The solution enables a reduction in remediation time of about 50%, compared with the continuous use of good-quality irrigation water. Because of its general structure, the bang–bang solution is also shown to work for the reclamation of other soil conditions, such as saline–sodic soils. The novelty in our modeling approach is the capability of searching the entire “strategy space” for optimal time-dependent protocols. The optimal solutions found for the minimalist model can be then fine-tuned by experiments and numerical simulations, applicable to realistic conditions that include spatial variability and heterogeneities.
Environmental exposure to pharmaceuticals: A new technique for trace analysis of carbamazepine and its metabolites in human urine
. Environmental Pollution 2016
, 308 - 313. Publisher's VersionAbstract
Pharmaceutically active compounds are taken up and accumulate in crops irrigated with treated wastewater. This raises the concern of chronic human exposure to pharmaceuticals via food consumption. Thus, there is a need to develop a reliable technique to detect and quantify pharmaceuticals at environmentally relevant concentrations in human biological matrices, particularly urine. In this study, we focus on carbamazepine, an antiepileptic drug and recalcitrant compound that is taken up by crops—making it an excellent model compound for this study. This paper presents a new analytical technique enabling quantification of trace concentrations of carbamazepine and its metabolites in the urine of individuals who have been environmentally exposed. Sample preparation included extraction with acetonitrile followed by clean-up through mixed-mode ion-exchange cartridges and analysis using LC/MS/MS. This technique, which was validated for a wide range of concentrations (5–2000 ng L−1), exhibits low limits of quantification (3.0–7.2 ng L−1), acceptable recovery levels (70–120%), and low relative standard deviation (<20%). Unlike currently available methods for the analysis of water or treated wastewater that require large volumes (up to 1 L), the new method uses only 10 mL of urine. Moreover, relative to available methods for carbamazepine detection in the urine of individuals who are chronically treated with this drug, the limit of quantification values with our method are six orders of magnitude lower. The newly developed method has been successfully applied for the quantification of carbamazepine and its metabolites in the urine of healthy people exposed to this pharmaceutical through their diet. Our analytical protocol can provide the scientific community and stakeholders with real data for risk assessments and the design of policies ensuring safe use of wastewater for crop irrigation.
Adsorption and desorption of dissolved organic matter by carbon nanotubes: Effects of solution chemistry
. Environmental Pollution 2016
, 90 - 98. Publisher's VersionAbstract
Increasing use of carbon nanotubes (CNTs) has led to their introduction into the environment where they can interact with dissolved organic matter (DOM). This study focuses on solution chemistry effects on DOM adsorption/desorption processes by single-walled CNTs (SWCNTs). Our data show that DOM adsorption is controlled by the attachment of DOM molecules to the SWCNTs, and that the initial adsorption rate is dependent on solution parameters. Adsorbed amount of DOM at high ionic strength was limited, possibly due to alterations in SWCNT bundling. Desorption of DOM performed at low pH resulted in additional DOM adsorption, whereas at high pH, adsorbed DOM amount decreased. The extent of desorption conducted at increased ionic strength was dependent on pre-adsorbed DOM concentration: low DOM loading stimulated additional adsorption of DOM, whereas high DOM loading facilitated release of adsorbed DOM. Elevated ionic strength and increased adsorbed amount of DOM reduced the oxidation temperature of the SWCNTs, suggesting that changes in the assembly of the SWCNTs had occurred. Moreover, DOM-coated SWCNTs at increased ionic strength provided fewer sites for atrazine adsorption. This study enhances our understanding of DOM–SWCNT interactions in aqueous systems influenced by rapid changes in salinity, and facilitates potential use of SWCNTs in water-purification technologies.